Osteoradionecrosis of the temporal bone RICHARD
T. RAMSDEN (London), CHARLES H. BULMAN (London) and BRIDGET P. LORIGAN (Dublin)
Introduction RADIOTHERAPY is universally accepted as an essential method of treating certain neoplasms in the head and neck. One of the factors which limits its usefulness, however, is the damage that adjacent healthy tissues may suffer. In the temporal bone the effects of external radiation on hearing and balance have attracted the attention of most authors (Kelemen, 1955; Borsanyi et al., 1961; Leach, 1965) and few studies have emphasized the osseus changes that may occur. Schuknecht and Karmody (1966) report two cases of osteoradionecrosis of the temporal bone which occurred following radiotherapy for a preauricular squamous cell carcinoma and an adenoid cystic carcinoma of the maxilla. Treatment in each case was with orthovoltage, the dose being 5,200 R and 6,700 R respectively, and the latent period between treatment and the onset of symptoms, nine years and four years. Both patients died, the first of intercurrent illness, but the other of otogenic meningitis, and the authors emphasize the danger of intracranial complications when osteoradionecrosis occurs. The temporal bones from these two patients were obtained for sectioning and reference will be made to their appearance. A few other isolated cases of radiation osteitis have been reported (Work, 1950; Block, 1952; Bragg et al., 1970). This paper presents the findings in a series of twenty-nine patients who developed necrosis of the temporal bone following radiotherapy to a variety of sites in the head and neck. Effects of Radiotherapy on the Middle and Inner Ear: Several experimental studies have examined the effects of radiation on the hearing of animals. Novotny (1951) noted a temporary reduction in hearing in guinea-pigs of 8-4 db. at 4,000 Hz. Girden (1935), on the other hand, found a short-lived gain in auditory acuity of about 5 db. in dogs exposed to radiation. The pathological changes in the middle ears and labyrinths of rats, following irradiation, were described by Kelemen (1955). In the middle ears mucosal oedema and haemorrhage were noted, the tympanic membrane was often haemorrhagic and a sterile effusion was often present. Kelemen (1955) recalls that the inner ear had hitherto been regarded as resistant to radiation damage, and confirms that in many cases an intact inner ear may exist alongside a grossly damaged middle ear. He did, however, find that haemorrhage into the scala media from 941
Richard T. Ramsden et al. the stria vascularis may occur, as may compression of the endolymphatic space from perilymphatic oedema. Borsanyi (1962), looking into the effects on the ears of 100 patients with head and neck malignancies treated with 4,000-6,000 R, found that 50 to 60 per cent of them developed ear symptoms, the commonest audiological change being a conductive deafness averaging 20 db., due to 'radiation otitis media', a sterile transudate similar to serous otitis. Although perceptive deafness was not a common finding in this series, a relatively large number of cases developed a temporary recruitment which Borsanyi attributes to a 'temporary vasculitis' of the cochlea. In a similar series Leach (1965) confirmed Borsanyi's findings, but in addition, warned of the occurrence of cochlear deafness which frequently did not recover. His series also included cases of partial or total labyrinthine loss coming on years after treatment. An interesting case report by Gyorkey and Pollock (i960) describes conductive deafness due to avascular necrosis of the lenticular process of the incus, occurring several years after radiation. The present series was compiled by reviewing records from four large medical centres of patients who had received radiotherapy for lesions of the head and neck, in whom it was felt that the fields employed might have involved the temporal bones. Twenty-nine cases of radionecrosis were discovered over a period of between twenty and thirty years, depending on the centre, but in no way is this presented as a true incidence of the condition. It was felt necessary to examine cases treated in the late 1940s and early 1950s in order to study patients treated on orthovoltage appliances. Two groups of patients emerged from the study: those in whom the temporal region or bone had been the main target for radiotherapeutic assault; and those in whom the ear had been in the periphery of a field directed primarily at some other site in the head, for example, the post-nasal space, or maxillary antrum. The type of unit used for the treatment and the total dose delivered were noted. Also recorded were the ages of patients at the time of radiotherapy and the interval ensuing between treatment and the first evidence of radionecrosis. Details of fractionation, field size and filtration were frequently not available in the notes, so that it was not possible over the series as a whole to extract any useful information about these factors. No attempt has been made to study the effect on the hearing or balance organs of treatment with radiation. Findings
A total of twenty-nine cases are described. Two main patterns of osteonecrosis of the temporal bone emerged, referred to as 'localized' and 'diffuse'. The first group comprises eighteen out of the twenty-nine cases, and in these patients the commonest finding (fifteen out of the 942
Osteoradionecrosis of the temporal bone eighteen) was an area of exposed dead bone in the external auditory meatus usually in the floor of the tympanic ring, though occasionally in the anterior wall. The commonest mode of presentation in these cases (thirteen out of eighteen) was with mild otalgia and offensive otorrhoea, though in two cases there was no discharge. Sequestration may be apparent on tomography, although the diagnosis is generally made without recourse to such investigation (Fig. i). A conservative line of treatment was followed, with regular toilet, ear drops and analgesics where necessary.
FIG. I .
Localized osteonecrosis of the tympanic ring. This tomograph shows an area of bone in the floor of the external meatus in the process of sequestring.
In the course of one to four years the sequestrum gradually separated completely, after which healing of the meatus, with loss of symptoms occurred, a process which has taken place in nine patients and appears to be progressing satisfactorily in three more. No attempt has been made to speed up the separation process surgically. In the two cases referred 943
Richard T. Ramsden et al. to above who did not have otorrhoea, the area of bare bone healed over spontaneously with no apparent sequestration. Three patients in this group of 'localized' necrosis of the temporal bone departed from the typical picture. Two of them suffered a slow dry sequestration of the outer cortex of the mastoid process following radiotherapy for a cerebellar astrocytoma and a squamous cell carcinoma of the pinna respectively. The third had radiotherapy following a radical mastoidectomy for carcinoma of the middle ear and developed an area of bare bone in the mastoid cavity with foul discharge. This settled down with conservative measures. Table I indicates the conditions for which patients in this 'localized' group were irradiated. It is significant that in twelve out of eighteen the radiotherapy was directed at primary lesions at some distance from the ear, namely, the postnasal space, tonsil, cerebellum, nose, maxilla and cervical lymph nodes. Patients in group 2 suffered diffuse osteonecrosis of the temporal bone. There are eleven patients in this group, in whom extensive ischaemic necrosis of a large part, or all of the temporal bone occurred. Table II indicates that in ten of the eleven cases the radiotherapy was directed primarily at the temporal bone, the middle ear or the skin of the external meatus, pinna or temporal region. Patients in this group suffered extreme boring pain, relieved only by opiates in many cases. Otorrhoea was profuse, pulsatile and offensive. Intracranial infection occurred in four of these cases: two of glomus jugulare tumour, one of rodent ulcer of the temple and one of squamous cell carcinoma of the postauricular skin. Two of these developed temporal lobe abscesses, one a temporal lobe abscess plus a cerebellar abscess, leading to death, and one a posterior fossa extra dural abscess. In two further cases the dura and lateral sinus had been extensively exposed and in four cases the facial canal or lateral semicircular canal had been eroded with either facial palsy, vertigo or a dead ear. One patient developed recurrent attacks of parotitis following destruction of the anterior meatal wall, and another developed trismus due to involvement in the osteonecrosis of the glenoid fossa. X-rays of the temporal bone may reveal a widespread moth-eaten area of radiolucency with loss of the normal cellular appearance of the mastoid cells (Fig. 2). Nine of these patients with diffuse osteonecrosis of the temporal bone have been explored surgically, radical mastoidectomy or partial petrosectomy being performed in an attempt to remove as much dead bone as possible. The normal hard bone of the petrous is replaced with soft mushy jelly-like tissue, fibrous and granulation tissue. Sequestra of dead bone are removed, but the difficulty in assessing the vitality of such tissue at operation is attested to by the fact that five of these patients required further exploration or sequestrectomies. 944
13. 14. 15. 16. 17. T8.
10. 11. 12.
9.
8.
1. 2. 3. 4. 5. 6. 7.
Squamous cell Ca of temple Basal cell Ca of temple Cerebellar astrocytoma Ca middle ear L glomus jugulare tumour Ca maxillary antrum (R) Lymphoepithelioma of tonsil + upper deep cervical node Ca pf post nasal space + upper deep cervical node (L) Ca of post nasal space + L upper deep cervical node R upper deep cervical node (no primary found) Nasal sarcoma Ca of post nasal space + R upper deep cervical node Squamous cell Ca of pinna Ca (R) tonsil + upper deep cervical nodes Ca palate Ca of post nasal space Squamous eel 1 Ca of L external auditory meatus Medullary glioma
Reason for radiotherapy
TABLE I.
R R R R R R ortho ortho ortho mega mega mega 17 years
Sequestrum of flooi of L external meatus Sequestrae of both external meatus Sequestrum of floor of external meatus Sequestrae of both tympanic rings Dry sequestrum of mastoid tip Sequestrum L (contralateral) external meatus Bilateral sequestrae of external meatus Sequestring bone in L meatus Sequestrum of L external meatal floor Bilateral sequestrae of tympanic rings
12 years 8 years 12 years 10 years 1 year 4 years 1 year 6 years 1 year 8 years
5125 R oitho 5000 R ortho 3766 R mega 35°o R mega 9500 R mega 6650 R 01 tho 7300 R mega
Sequestrum of floor of L external meatus
Sequestrae of both external auditory meatus
10 years 14 years 23 years 9 months 8 years 5 years
11 years
Comment Bare bone of anterior meatal wall Sequestrum of flooi of external meatus Area of dead bone behind pinna Bare bone in mastoid bowl Sequestrum floor of external meatus Sequestrum floor of R external auditory meatus
Latent period
3000 R ortho 3325 R ortho 3050 R ortho
3034 R mega
9600 R ortho
2500 7000 4780 6000 4000 9500
R.T. details
LOCALIZED OSTEONECROSIS OF TEMPORAL BONE
Si.
1
3
(-6
n>
3
o o
o
5650 R mega 4000 R ortho
3. R glomus jugulare tumour
4. Cerebellar haemangioblastoma
7000 R ortho 3200 R ortho 6650 R mega 2000 R ortho 4800 R ortho 5500 R mega
6. Basal cell Ca R pinna
7. Secondary carcinoma (1° breast)
8. Ca L middle ear
a. Basal cell Ca R temple
TO. Squamous cell Ca R post-auricular skin
11. Ca L middle ear
? dose ortho
6409 R mega
2. R glomus jugulare tumour
O~- 5. Otitis externa
6230 R mega
R.T. details
1. R glomus jugulare tumour
Reason for radiotherapy
TABLE II.
8 years
2 years
6 years
1 year
4 years
17 years
6 years
18 years
2 years
2 years
18 years
Latent period Comment
Facial palsy, sequestration of labyrinth, exposed dura.
Temporal lobe abscess.
Fistula into parotid, temporal lobe abscess.
Exposed dura, facial nerve and labyrinth. Necrotic mastoid process with fistula into external meatus. Severe pain. Necrosis of mastoid process with fistula into external meatus. Sequestring mastoid process with post aural fistula.
Widespread necrosis of petrous temporal bone. Extra dural abscess, post fossa. Necrosis of mastoid cavity. Labyrinthine involvement with dead ear and vertigo. Gross necrosis of petrous bone. Temporal lobe and cerebellar abscesses, DEATH. Sinus from mastoid to external meatus. Necrotic mastoid process. Dura and lateral sinus exposed. Temporomandibular joint involved. Dead labyrinth.
DIFFUSE OSTEONECROS1S OF TEMPORAL BONE
El
n
Osteoradionecrosis of the temporal bone
FIG.
2.
Diffuse osteonecrosis of the right temporal bone. There is a hazy translucency of the mastoid and part of the petrous bone, with loss of the normal air-cells (cf. opposite side).
Seventeen of the series of twenty-nine patients were treated on orthovoltage machines and twelve by megavoltage, mostly Cobalt 60 units. There was no difference between the 'localized' and 'diffuse' groups as to which type of unit had been used. Seven out of the eighteen (40 per cent) in the localized group and five out of the eleven (45 per cent) of the 'diffuse' group received megavoltage treatment. The dosage varied from 2,500 R to 9,600 R in the 'localized' group, and from 2,000 R to 7,000 R in the 'diffuse' group (Tables I and II). The time interval between treatment and clinical evidence of osteonecrosis varied greatly, from less than one year to twenty-three years (Tables I, II and III). The average interval appears to be shorter with megavoltage than with orthovoltage (five years as against ten years in this 947
Richard T. Ramsden et al. TABLE III. AGES OF PATIENTS AT THE TIME OF RADIOTHERAPY PLOTTED AGAINST THE LATENT PERIOD WHICH ELASPED BEFORE THE ONSET OF OBVIOUS OSTEORADIONECROSIS. IT IS UNCOMMON FOR NECROSIS TO DEVELOP IN UNDER EIGHT YEARS IN PATIENTS UNDER FORTY AT THE TIME OF RADIOTHERAPY.
OSTEORADIONECROSIS OF TEMPORAL BONE
2422 20
18 im
16
flj 01 >,
•o a L.
14 12
a
c 41
10
8642I 20
30
40
50
60
70
Age of patient at t i m e of RT
series), but this may to some extent be explained by the fact that most patients who were treated by orthovoltage have been followed up for a longer period of time than those treated by the more recent megavoltage techniques. The length of time that elapses before the onset of obvious osteonecrosis does not appear to bear any relationship to the eventual severity of the complication. Three of those who eventually developed diffuse necrosis of their temporal bones were trouble-free for over fifteen years from the date of their treatment. An attempt was made to correlate the age of the patient at the time of radiotherapy with the time lapse before the onset of osteoradionecrosis. The findings are recorded graphically in Table III. 948
Osteoradionecrosis of the temporal bone Four cases are described in detail to illustrate certain points. Case r describes the progression in typical localized radionecrosis, Cases 2 and 3 point out the dangers of intracranial complications of diffuse disease, and Case 4 warns of the potential hazards of radiotherapy in benign conditions. Case reports Case 1
This man was 40 years old when treated in 1956 for an undifferentiated squamous cell carcinoma of the right tonsil with upper deep cervical nodes. 3766R weie given on a 1,000 KV unit. Between 1957 and 1959 the patient complained of pain and irritation in the left ear, and in i960 an area of exposed bone became visible in the floor of the external auditory meatus. During the next three years this area of bone was observed gradually to sequestrate, after which the meatal skin healed over. The patient remains well. Case 2
This 44-year-old woman was treated in 1965 for a right glomus jugulare tumour which on presentation had already involved the 7th, 8th and 10th cranial nerves. She received a total of 5,650 R in eight weeks on a Co 60 unit. Within two years of treatment she began to complain of increasingly severe pain in the right ear and profuse foul discharge. An area of exposed bone was present in the floor of the external auditory meatus, and the ear was full of thick offensive pus. Treatment with local toilet, drops and analgesics was pursued for the following six years, during which time the severity of the pain and discharge varied, but a steadily progressive involvement of the cranial nerves on the right side occurred, so that by 1969 there was evidence of involvement of V, VII, VIII, IX, X, XI and XII. In 1973 the ear was explored and a large sequestrum of petrous temporal bone removed. The middle and posterior fossae dura, as well as the internal carotid artery were found to be exposed, but there was no sign of residual glomus tumour. During the next twelve months three further sequestiectomies were carried out, as well as excision of the pinna, which had become grossly affected by perichondritis. The patient continued to deteriorate and required increasingly large doses of opiate for relief of severe deep boring pain until her eventual death. At post mortem two abscesses, each of about 3 inches in diameter were found, one in the right temporal lobe and one in the right cerebellar hemisphere. What little temporal bone remained was necrotic, but there was no glomus tumour present. Figure 3 shows the temporal bone section at post-mortem, demonstrating the replacement of bone by a large area of reparative fibrosis. Marked destruction of the cochlea has also occurred. Case 3 In 1952, this woman, then aged 52, presented to her otologist complaining of a recent discharge from her right ear. The diagnosis of otitis externa secondary to chronic suppurative otitis media was made and conservative measures were instituted, without much improvement. Six months later she presented, 949
Richard T. Ramsden et al.
FIG. 3. Case 2. Post mortem temporal bone section showing replacement of a large area of bone by fibrous tissue. The facial nerve (top right) is surrounded by fibrous tissue. Gross disruption of the cochlea has occurred with loss of the basilar and Reissner's membranes, and there is haemorrhage into the cochlea.
complaining, in addition to her otorrhoea, of recurrent right facial swelling, which was diagnosed as recurrent parotitis. Only at this stage did the fact emerge that six years previously she had had a course of radiotherapy for a basal cell carcinoma of the skin of the right temple (2,000 R on a 220 KY machine). Two weeks later she was admitted with a right temporal lobe abscess. The right mastoid was explored and the following comments were made: '. . . a good deal of bony necrosis had occurred above and behind the anterior process of the zygoma. The bone in this area was partly adherent to the dura of the middle fossa, which was granular and thick . . . The attic contained particularly firm, unhealthy granulation tissue and there was sequestration of the anterior bony meatal wall and a fistula containing granulation leadings into the parotid area. The mastoid process was most unusually softened and unhealthy . . . A large area of the dura of the middle fossa, sinodural angle and lateral sinus was exposed, giving a good view of the superior petrosal sinus.' Gradual resolution of the abscess occurred, but a second mastoid exploration was necessary two years later to remove the sequestered facial ridge. A healthy mastoid cavity was eventually obtained, but the patient was left with a partial facial palsy. Case 4 This man received a course of radiotherapy in 1952 for bilateral otitis externa, which had proved unresponsive to conventional therapy. An orthovoltage unit was used, but the dose is not known. Worsening pain and foul, 950
Osteoradionecrosis of the temporal bone profuse otorrhoea developed gradually about five years after radiotherapy. Trismus became marked. Two mastoid explorations were carried out, at which the middle ear cleft was found to be filled with granulation and fibrous tissue. The superior and anteiior bony meatal walls had sequestered, as had part of the glenoid fossa, so that a communication existed between the middle ear and the temporomandibular joint. After the second sequestrectomy, the ear settled satisfactorily, but the patient was left with a profound sensorineural deafness and vertigo. Discussion
Normal mature bone is usually regarded as being relatively resistant to the harmful effects of radiotherapy and can be irradiated therapeutically with impunity (Lederman, 1965), a property which in part may be attributed to the filtering effects of the overlying soft tissue (Work, 1950). Those who treat intraoral malignancies, however, are well aware of the threat of radionecrosis of the mandible, an 'acceptable incidence' of which is stated by Rankow and Weissman (1971) to be 5 to 10 per cent. Several factors make the mandible more vulnerable to necrosis following radiotherapy: the close proximity of infected mouth or teeth, a relatively precarious blood supply (Dalley, 1973), and a superficial position which minimizes the soft tissue filtering effect at the same time as increasing the risk of direct trauma. The temporal bone, too, is superficially placed, protected only by the skin over the mastoid and the very thin skin of the external auditory meatus. It is in communication by way of the Eustachian tube with a potentially infected upper respiratory tract, and it appears that the blood supply of the tympanic ring at any rate is not good, as this is the part of the temporal bone most frequently seen to be involved in radionecrosis. Compact bone such as the temporal bone tolerates irradiation less well than cancellous bone, and this tolerance is further reduced when bone is invaded by neoplasm or is infected (Lederman, 1965). The need to deliver a cancericidal dose to bone invaded by new growth results in a greatly increased risk of radionecrosis (Schuknecht and Karmody, 1966). Pathogenesis: The underlying change in 'radiation osteitis' (Ewing, 1926) is aseptic avascular necrosis, the basis for which is the radiationinduced changes in the blood vessels supplying the bone. Ewing described a loss of vascularity resulting from obliterative endarteritis and periarteritis. Most elements in the vessel walls exhibit degenerative change, in particular smooth muscle and collagen, and the endothelium may so swell up as to narrow or even obliterate the lumen, increasing the risk of thrombus formation. At a late stage the vessels may atrophy or disappear or be replaced by a hyaline material (Gyorkey and Pollock, i960). Demineralization of bone occurs as osteolysis proceeds in the absence of any osteoblastic activity, and attempted repair occurs by fibrosis.
Richard T. Ramsden et al. Histologically there is an almost complete absence of osteocytes and osteoblasts, with empty lacunae, and a preponderance of osteoclasts, while spicules of dead bone may be surrounded by connective tissue (Schuknecht and Karmody, 1966). If infection is introduced, necrosis becomes more rapid. Ewing (1926) maintained that dead bone was a favourable site for bacteriological colinization by virtue of the protection offered by the Haversian system from leucocytic attack. This process continues slowly so that there may be a long latent period between irradiation and the onset of symptoms (in our series up to twenty-three years), a phenomenon which Ewing attributed to the slow metabolic turnover of bone compared with other tissues. Early symptoms such as otalgia or otorrhoea should lead one to suspect residual tumour, but we cannot agree with the statement of Bragg et al. (1970) that any change occurring after five years is more likely to be radiation sarcoma than osteonecrosis. It has been suggested (Woodard and Coley, 1947) that young people are better able to withstand the harmful effects of irradiation of bone than the old. We plotted the age of the patients at the time of radiotherapy against the latent period before osteonecrosis became evident (Table III). Although this is a small sample, it appears that patients under the age of 40 at the time of radiotherapy are unlikely to develop osteonecrosis in under eight years, whereas twelve of the twenty patients aged 40 and over had developed obvious necrosis within six years. If this is a valid observation, it suggests that the process of obliterative endarteritis is prolonged and continues long after the initial injury. A younger patient with a less precarious arterial tree may therefore take longer to reach the point of bone death. Nature of Irradiation: The degree of damage caused by radiotherapy is generally held to be in direct proportion to the dosage. The pertinent figure, however, is the dosage received by the tissues and not simply that emitted by the appliance in use. The former obviously depends upon the latter, but other factors, such as fractionation, filtering and field size, all influence the true figure. For this reason we have found it impossible to calculate the actual dose of radiation received by any one temporal bone and, although we have recorded the doses as they appeared in the case notes of the patients in this series, we have found them of little help in drawing conclusions. More important in establishing a dose relationship, is the occurrence of two distinct groups of patients: those with diffuse radionecrosis, in whom the temporal bone had been the prime target of irradiation, or at least close to the centre of the field, and, in contrast, the group with localized necrosis of the tympanic plate, a much less serious condition, the majority of whom had been irradiated for lesions at a distance from the ear, the temporal bone thus falling in the periphery of the irradiated field. The type of appliance used for irradiation is said to influence the 952
Osteoradionecrosis of the temporal bone incidence of osteoradionecrosis (Dalley, 1973). With 250 kv. orthovoltage the energy absorption by bone is two-and-a-half times that of soft tissue, whereas with megavoltage absorption by bone and soft tissue is equal (Meyer et al., 1962). One would, therefore, expect the incidence of this complication to be decreasing since the introduction of Co. 60 appliances, and to a certain extent this has happened (Bragg et al., 1970). Rankow and Weissman (1971), however, state that in their experience there has been no decrease in the incidence of osteoradionecrosis of the mandible with megavoltage. In our series of twenty-nine cases of the temporal bone, twelve had been treated by megavoltage, and of those twelve five suffered diffuse involvement; so, although in no way have we attempted to present a true incidence, it is apparent that radionecrosis of the temporal bone still does occur with megavoltage treatment. As the voltage of X-rays increases, so does the depth of penetration. Low (100 kv.) voltage units have little penetration and are used mainly for the treatment of superficial skin lesions. A Co 60 unit, however, produces its maximum effect (4 mm.) beneath the skin (Harrison, 1971). which is thus spared, but the underlying tissues receive the maximum dose. This may place a superficial bone (mandible or temporal bone) at added risk. The clinical picture in the localized type of disease is of otitis externa which may prove slow to resolve. Usually its true nature is recognized early in that the patient is attending a radiotherapy follow-up clinic. Where the original lesion has been a neoplasm of the middle or external ear, the alternative diagnosis of residual disease must be considered and any suspicious area biopsied. Occasionally, however, the diagnosis of osteonecrosis may elude the clinician for many weeks, during which he thinks he is merely dealing with a stubborn otitis externa. This is particularly likely if, as may happen, many years have elapsed since the radiotherapy. The patient may have fogotten a short course of treatment fifteen years previously for a small rodent ulcer on the cheek, or may not associate it with his present trouble. Case 4 illustrates the hazards of using radiotherapy for relatively trivial complaints, and it is worth bearing in mind that otitis externa, otosclerosis (Nylen, i960) Eustachian tube dysfunction and tinnitus have all been treated at some time by radiotherapy. Otititis externa which is proving resistant to conventional therapy, particularly in the presence of exposed or sequestering bone in the tympanic ring, should prompt the otologist to enquire about previous irradiation to the area. Conservative measures during the process of spontaneous sequestration are all that are required, after which healing may be expected, the whole process taking up to four years. Diffuse osteoradionecrosis of the temporal bone is a serious condition with a high risk of involvement of adjacent structures, particularly the 953
Richard T. Ramsden et al. facial nerve, labyrinth, lateral sinus, temporal lobe and cerebellum, and, less frequently, the parotid gland and temporo-mandibular joint. Severe pain and profuse offensive otorrhoea following radiotherapy are the clues to its presence, although the time interval between irradiation and the onset of necrosis may again cloud the issue. Treatment is surgical: early and radical exploration of the mastoid. Summary
A series of twenty-nine cases of osteoradionecrosis of the temporal bone is described. Two patterns occur: a localized involvement of the tympanic plate which resolves after the spontaneous separation of a sequestrum of bone, and a more diffuse necrosis of the temporal bone with a high risk of involvement of adjacent structures, in particular the brain, labyrinth and facial nerve and to a lesser extent the temporomandibular joint and the parotid gland. Localized osteonecrosis occurs more commonly when the temporal bone is in the periphery of an irradiated field whereas irradiation aimed primarily at the temporal bone is more likely to be followed by diffuse disease. The use of megavoltage irradiation has not lead to the disappearance of the complication which may occur as much as twenty years after the completion of the course of radiotherapy. Acknowledgements
We are grateful to those consultants from the Royal National Throat, Nose and Ear Hospital, St. Bartholomew's Hospital and The National Hospital for Nervous Diseases, London, and St. George's Hospital, Lincoln, who allowed us to report cases under their care, in particular, Mr. M. Spencer Harrison for his interest and help. We wish to thank the Photographic Departments of the Royal National Throat, Nose and Ear Hospital and St. Bartholomew's Hospital for the illustrations. REFERENCES BLOCK, E (1952) Zeitschrift fur Hals, Nase, und Ohrenheilkunde, 3, 45. BORSANYI, S (1962) Southern Medical Journal, 55, 740. BORSANYI, S., BLANCHARD, C. L., and THORNE, B. (1961) Annals of Otology, Rhin-
ology and Laryngology, 70, 255. BRAGG, D. G., SHIDNIA, H., CHU, F. C. H., and HIGINBOTHAM, N. L. (1970), Radi-
ology, 97, 103. DALLEY, V. M. (1973) In Recent Advances in Otolaryngology, 4th edition, Chapter 26, edited by J. Ransome, H. Holden and T. R. Bull. Churchill Livingstone, Edinburgh and London. EWING, J. (1926) Ada Radiologica 6, 400. GIRDEN, E. (1935) Journal of Comparative Psychology, 20, 263. GYORKEY, Z., and POLLOCK, F. J. (i960) Archives of Otolaryngology, 71, 793. HARRISON, D. F. N. (1971) In Scott-Brown's Diseases of the Ear, Nose and Throat, 3rd edition, volume 4, page 493, edited by J. Ballantyne and J. Groves, Butterworths, London.
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Osteoradionecrosis of the temporal bone KELEMEN, G. (1955) Archives of Otolaryngology, 61, 405. LEACH, W. (1965) Journal of Laryngology and Otology, 79, 870. LEDERMAN, M. (1965) Journal of Laryngology and Otology, 79, 85. MEYER, I., SHKLAR, G., and TURNER, J. (1962) Oral Surgery, 15, 1098.
NOVOTNY, O. (1951) Archivio Italiano di Otologia, Rinologia e Laryngologia, 62, 15. XYLEN, C. O. (1960) Ada Otolaryngologica, 51, 507. RAXKOW, R. M., and WEISSMAN, B. (1971) Annals of Otology, Rhinology and Laryngology, 80, 603. SCHUKNECHT, H. F. and KARMODY, C. S. (1966) Laryngoscope, 76, 1416.
WOODARD, H. Q., and COLEY, B. K. (1947) American Journal of Roentgenology, 57, 464. WORK, W. P. (1950) Annals of Otology, Rhinology and Laryngology, 59, 1062. E.X.T. Department, The London Hospital, Whitechapel, London El iBB.
955
T. RAMSDEN (London), CHARLES H. BULMAN (London) and BRIDGET P. LORIGAN (Dublin)
Introduction RADIOTHERAPY is universally accepted as an essential method of treating certain neoplasms in the head and neck. One of the factors which limits its usefulness, however, is the damage that adjacent healthy tissues may suffer. In the temporal bone the effects of external radiation on hearing and balance have attracted the attention of most authors (Kelemen, 1955; Borsanyi et al., 1961; Leach, 1965) and few studies have emphasized the osseus changes that may occur. Schuknecht and Karmody (1966) report two cases of osteoradionecrosis of the temporal bone which occurred following radiotherapy for a preauricular squamous cell carcinoma and an adenoid cystic carcinoma of the maxilla. Treatment in each case was with orthovoltage, the dose being 5,200 R and 6,700 R respectively, and the latent period between treatment and the onset of symptoms, nine years and four years. Both patients died, the first of intercurrent illness, but the other of otogenic meningitis, and the authors emphasize the danger of intracranial complications when osteoradionecrosis occurs. The temporal bones from these two patients were obtained for sectioning and reference will be made to their appearance. A few other isolated cases of radiation osteitis have been reported (Work, 1950; Block, 1952; Bragg et al., 1970). This paper presents the findings in a series of twenty-nine patients who developed necrosis of the temporal bone following radiotherapy to a variety of sites in the head and neck. Effects of Radiotherapy on the Middle and Inner Ear: Several experimental studies have examined the effects of radiation on the hearing of animals. Novotny (1951) noted a temporary reduction in hearing in guinea-pigs of 8-4 db. at 4,000 Hz. Girden (1935), on the other hand, found a short-lived gain in auditory acuity of about 5 db. in dogs exposed to radiation. The pathological changes in the middle ears and labyrinths of rats, following irradiation, were described by Kelemen (1955). In the middle ears mucosal oedema and haemorrhage were noted, the tympanic membrane was often haemorrhagic and a sterile effusion was often present. Kelemen (1955) recalls that the inner ear had hitherto been regarded as resistant to radiation damage, and confirms that in many cases an intact inner ear may exist alongside a grossly damaged middle ear. He did, however, find that haemorrhage into the scala media from 941
Richard T. Ramsden et al. the stria vascularis may occur, as may compression of the endolymphatic space from perilymphatic oedema. Borsanyi (1962), looking into the effects on the ears of 100 patients with head and neck malignancies treated with 4,000-6,000 R, found that 50 to 60 per cent of them developed ear symptoms, the commonest audiological change being a conductive deafness averaging 20 db., due to 'radiation otitis media', a sterile transudate similar to serous otitis. Although perceptive deafness was not a common finding in this series, a relatively large number of cases developed a temporary recruitment which Borsanyi attributes to a 'temporary vasculitis' of the cochlea. In a similar series Leach (1965) confirmed Borsanyi's findings, but in addition, warned of the occurrence of cochlear deafness which frequently did not recover. His series also included cases of partial or total labyrinthine loss coming on years after treatment. An interesting case report by Gyorkey and Pollock (i960) describes conductive deafness due to avascular necrosis of the lenticular process of the incus, occurring several years after radiation. The present series was compiled by reviewing records from four large medical centres of patients who had received radiotherapy for lesions of the head and neck, in whom it was felt that the fields employed might have involved the temporal bones. Twenty-nine cases of radionecrosis were discovered over a period of between twenty and thirty years, depending on the centre, but in no way is this presented as a true incidence of the condition. It was felt necessary to examine cases treated in the late 1940s and early 1950s in order to study patients treated on orthovoltage appliances. Two groups of patients emerged from the study: those in whom the temporal region or bone had been the main target for radiotherapeutic assault; and those in whom the ear had been in the periphery of a field directed primarily at some other site in the head, for example, the post-nasal space, or maxillary antrum. The type of unit used for the treatment and the total dose delivered were noted. Also recorded were the ages of patients at the time of radiotherapy and the interval ensuing between treatment and the first evidence of radionecrosis. Details of fractionation, field size and filtration were frequently not available in the notes, so that it was not possible over the series as a whole to extract any useful information about these factors. No attempt has been made to study the effect on the hearing or balance organs of treatment with radiation. Findings
A total of twenty-nine cases are described. Two main patterns of osteonecrosis of the temporal bone emerged, referred to as 'localized' and 'diffuse'. The first group comprises eighteen out of the twenty-nine cases, and in these patients the commonest finding (fifteen out of the 942
Osteoradionecrosis of the temporal bone eighteen) was an area of exposed dead bone in the external auditory meatus usually in the floor of the tympanic ring, though occasionally in the anterior wall. The commonest mode of presentation in these cases (thirteen out of eighteen) was with mild otalgia and offensive otorrhoea, though in two cases there was no discharge. Sequestration may be apparent on tomography, although the diagnosis is generally made without recourse to such investigation (Fig. i). A conservative line of treatment was followed, with regular toilet, ear drops and analgesics where necessary.
FIG. I .
Localized osteonecrosis of the tympanic ring. This tomograph shows an area of bone in the floor of the external meatus in the process of sequestring.
In the course of one to four years the sequestrum gradually separated completely, after which healing of the meatus, with loss of symptoms occurred, a process which has taken place in nine patients and appears to be progressing satisfactorily in three more. No attempt has been made to speed up the separation process surgically. In the two cases referred 943
Richard T. Ramsden et al. to above who did not have otorrhoea, the area of bare bone healed over spontaneously with no apparent sequestration. Three patients in this group of 'localized' necrosis of the temporal bone departed from the typical picture. Two of them suffered a slow dry sequestration of the outer cortex of the mastoid process following radiotherapy for a cerebellar astrocytoma and a squamous cell carcinoma of the pinna respectively. The third had radiotherapy following a radical mastoidectomy for carcinoma of the middle ear and developed an area of bare bone in the mastoid cavity with foul discharge. This settled down with conservative measures. Table I indicates the conditions for which patients in this 'localized' group were irradiated. It is significant that in twelve out of eighteen the radiotherapy was directed at primary lesions at some distance from the ear, namely, the postnasal space, tonsil, cerebellum, nose, maxilla and cervical lymph nodes. Patients in group 2 suffered diffuse osteonecrosis of the temporal bone. There are eleven patients in this group, in whom extensive ischaemic necrosis of a large part, or all of the temporal bone occurred. Table II indicates that in ten of the eleven cases the radiotherapy was directed primarily at the temporal bone, the middle ear or the skin of the external meatus, pinna or temporal region. Patients in this group suffered extreme boring pain, relieved only by opiates in many cases. Otorrhoea was profuse, pulsatile and offensive. Intracranial infection occurred in four of these cases: two of glomus jugulare tumour, one of rodent ulcer of the temple and one of squamous cell carcinoma of the postauricular skin. Two of these developed temporal lobe abscesses, one a temporal lobe abscess plus a cerebellar abscess, leading to death, and one a posterior fossa extra dural abscess. In two further cases the dura and lateral sinus had been extensively exposed and in four cases the facial canal or lateral semicircular canal had been eroded with either facial palsy, vertigo or a dead ear. One patient developed recurrent attacks of parotitis following destruction of the anterior meatal wall, and another developed trismus due to involvement in the osteonecrosis of the glenoid fossa. X-rays of the temporal bone may reveal a widespread moth-eaten area of radiolucency with loss of the normal cellular appearance of the mastoid cells (Fig. 2). Nine of these patients with diffuse osteonecrosis of the temporal bone have been explored surgically, radical mastoidectomy or partial petrosectomy being performed in an attempt to remove as much dead bone as possible. The normal hard bone of the petrous is replaced with soft mushy jelly-like tissue, fibrous and granulation tissue. Sequestra of dead bone are removed, but the difficulty in assessing the vitality of such tissue at operation is attested to by the fact that five of these patients required further exploration or sequestrectomies. 944
13. 14. 15. 16. 17. T8.
10. 11. 12.
9.
8.
1. 2. 3. 4. 5. 6. 7.
Squamous cell Ca of temple Basal cell Ca of temple Cerebellar astrocytoma Ca middle ear L glomus jugulare tumour Ca maxillary antrum (R) Lymphoepithelioma of tonsil + upper deep cervical node Ca pf post nasal space + upper deep cervical node (L) Ca of post nasal space + L upper deep cervical node R upper deep cervical node (no primary found) Nasal sarcoma Ca of post nasal space + R upper deep cervical node Squamous cell Ca of pinna Ca (R) tonsil + upper deep cervical nodes Ca palate Ca of post nasal space Squamous eel 1 Ca of L external auditory meatus Medullary glioma
Reason for radiotherapy
TABLE I.
R R R R R R ortho ortho ortho mega mega mega 17 years
Sequestrum of flooi of L external meatus Sequestrae of both external meatus Sequestrum of floor of external meatus Sequestrae of both tympanic rings Dry sequestrum of mastoid tip Sequestrum L (contralateral) external meatus Bilateral sequestrae of external meatus Sequestring bone in L meatus Sequestrum of L external meatal floor Bilateral sequestrae of tympanic rings
12 years 8 years 12 years 10 years 1 year 4 years 1 year 6 years 1 year 8 years
5125 R oitho 5000 R ortho 3766 R mega 35°o R mega 9500 R mega 6650 R 01 tho 7300 R mega
Sequestrum of floor of L external meatus
Sequestrae of both external auditory meatus
10 years 14 years 23 years 9 months 8 years 5 years
11 years
Comment Bare bone of anterior meatal wall Sequestrum of flooi of external meatus Area of dead bone behind pinna Bare bone in mastoid bowl Sequestrum floor of external meatus Sequestrum floor of R external auditory meatus
Latent period
3000 R ortho 3325 R ortho 3050 R ortho
3034 R mega
9600 R ortho
2500 7000 4780 6000 4000 9500
R.T. details
LOCALIZED OSTEONECROSIS OF TEMPORAL BONE
Si.
1
3
(-6
n>
3
o o
o
5650 R mega 4000 R ortho
3. R glomus jugulare tumour
4. Cerebellar haemangioblastoma
7000 R ortho 3200 R ortho 6650 R mega 2000 R ortho 4800 R ortho 5500 R mega
6. Basal cell Ca R pinna
7. Secondary carcinoma (1° breast)
8. Ca L middle ear
a. Basal cell Ca R temple
TO. Squamous cell Ca R post-auricular skin
11. Ca L middle ear
? dose ortho
6409 R mega
2. R glomus jugulare tumour
O~- 5. Otitis externa
6230 R mega
R.T. details
1. R glomus jugulare tumour
Reason for radiotherapy
TABLE II.
8 years
2 years
6 years
1 year
4 years
17 years
6 years
18 years
2 years
2 years
18 years
Latent period Comment
Facial palsy, sequestration of labyrinth, exposed dura.
Temporal lobe abscess.
Fistula into parotid, temporal lobe abscess.
Exposed dura, facial nerve and labyrinth. Necrotic mastoid process with fistula into external meatus. Severe pain. Necrosis of mastoid process with fistula into external meatus. Sequestring mastoid process with post aural fistula.
Widespread necrosis of petrous temporal bone. Extra dural abscess, post fossa. Necrosis of mastoid cavity. Labyrinthine involvement with dead ear and vertigo. Gross necrosis of petrous bone. Temporal lobe and cerebellar abscesses, DEATH. Sinus from mastoid to external meatus. Necrotic mastoid process. Dura and lateral sinus exposed. Temporomandibular joint involved. Dead labyrinth.
DIFFUSE OSTEONECROS1S OF TEMPORAL BONE
El
n
Osteoradionecrosis of the temporal bone
FIG.
2.
Diffuse osteonecrosis of the right temporal bone. There is a hazy translucency of the mastoid and part of the petrous bone, with loss of the normal air-cells (cf. opposite side).
Seventeen of the series of twenty-nine patients were treated on orthovoltage machines and twelve by megavoltage, mostly Cobalt 60 units. There was no difference between the 'localized' and 'diffuse' groups as to which type of unit had been used. Seven out of the eighteen (40 per cent) in the localized group and five out of the eleven (45 per cent) of the 'diffuse' group received megavoltage treatment. The dosage varied from 2,500 R to 9,600 R in the 'localized' group, and from 2,000 R to 7,000 R in the 'diffuse' group (Tables I and II). The time interval between treatment and clinical evidence of osteonecrosis varied greatly, from less than one year to twenty-three years (Tables I, II and III). The average interval appears to be shorter with megavoltage than with orthovoltage (five years as against ten years in this 947
Richard T. Ramsden et al. TABLE III. AGES OF PATIENTS AT THE TIME OF RADIOTHERAPY PLOTTED AGAINST THE LATENT PERIOD WHICH ELASPED BEFORE THE ONSET OF OBVIOUS OSTEORADIONECROSIS. IT IS UNCOMMON FOR NECROSIS TO DEVELOP IN UNDER EIGHT YEARS IN PATIENTS UNDER FORTY AT THE TIME OF RADIOTHERAPY.
OSTEORADIONECROSIS OF TEMPORAL BONE
2422 20
18 im
16
flj 01 >,
•o a L.
14 12
a
c 41
10
8642I 20
30
40
50
60
70
Age of patient at t i m e of RT
series), but this may to some extent be explained by the fact that most patients who were treated by orthovoltage have been followed up for a longer period of time than those treated by the more recent megavoltage techniques. The length of time that elapses before the onset of obvious osteonecrosis does not appear to bear any relationship to the eventual severity of the complication. Three of those who eventually developed diffuse necrosis of their temporal bones were trouble-free for over fifteen years from the date of their treatment. An attempt was made to correlate the age of the patient at the time of radiotherapy with the time lapse before the onset of osteoradionecrosis. The findings are recorded graphically in Table III. 948
Osteoradionecrosis of the temporal bone Four cases are described in detail to illustrate certain points. Case r describes the progression in typical localized radionecrosis, Cases 2 and 3 point out the dangers of intracranial complications of diffuse disease, and Case 4 warns of the potential hazards of radiotherapy in benign conditions. Case reports Case 1
This man was 40 years old when treated in 1956 for an undifferentiated squamous cell carcinoma of the right tonsil with upper deep cervical nodes. 3766R weie given on a 1,000 KV unit. Between 1957 and 1959 the patient complained of pain and irritation in the left ear, and in i960 an area of exposed bone became visible in the floor of the external auditory meatus. During the next three years this area of bone was observed gradually to sequestrate, after which the meatal skin healed over. The patient remains well. Case 2
This 44-year-old woman was treated in 1965 for a right glomus jugulare tumour which on presentation had already involved the 7th, 8th and 10th cranial nerves. She received a total of 5,650 R in eight weeks on a Co 60 unit. Within two years of treatment she began to complain of increasingly severe pain in the right ear and profuse foul discharge. An area of exposed bone was present in the floor of the external auditory meatus, and the ear was full of thick offensive pus. Treatment with local toilet, drops and analgesics was pursued for the following six years, during which time the severity of the pain and discharge varied, but a steadily progressive involvement of the cranial nerves on the right side occurred, so that by 1969 there was evidence of involvement of V, VII, VIII, IX, X, XI and XII. In 1973 the ear was explored and a large sequestrum of petrous temporal bone removed. The middle and posterior fossae dura, as well as the internal carotid artery were found to be exposed, but there was no sign of residual glomus tumour. During the next twelve months three further sequestiectomies were carried out, as well as excision of the pinna, which had become grossly affected by perichondritis. The patient continued to deteriorate and required increasingly large doses of opiate for relief of severe deep boring pain until her eventual death. At post mortem two abscesses, each of about 3 inches in diameter were found, one in the right temporal lobe and one in the right cerebellar hemisphere. What little temporal bone remained was necrotic, but there was no glomus tumour present. Figure 3 shows the temporal bone section at post-mortem, demonstrating the replacement of bone by a large area of reparative fibrosis. Marked destruction of the cochlea has also occurred. Case 3 In 1952, this woman, then aged 52, presented to her otologist complaining of a recent discharge from her right ear. The diagnosis of otitis externa secondary to chronic suppurative otitis media was made and conservative measures were instituted, without much improvement. Six months later she presented, 949
Richard T. Ramsden et al.
FIG. 3. Case 2. Post mortem temporal bone section showing replacement of a large area of bone by fibrous tissue. The facial nerve (top right) is surrounded by fibrous tissue. Gross disruption of the cochlea has occurred with loss of the basilar and Reissner's membranes, and there is haemorrhage into the cochlea.
complaining, in addition to her otorrhoea, of recurrent right facial swelling, which was diagnosed as recurrent parotitis. Only at this stage did the fact emerge that six years previously she had had a course of radiotherapy for a basal cell carcinoma of the skin of the right temple (2,000 R on a 220 KY machine). Two weeks later she was admitted with a right temporal lobe abscess. The right mastoid was explored and the following comments were made: '. . . a good deal of bony necrosis had occurred above and behind the anterior process of the zygoma. The bone in this area was partly adherent to the dura of the middle fossa, which was granular and thick . . . The attic contained particularly firm, unhealthy granulation tissue and there was sequestration of the anterior bony meatal wall and a fistula containing granulation leadings into the parotid area. The mastoid process was most unusually softened and unhealthy . . . A large area of the dura of the middle fossa, sinodural angle and lateral sinus was exposed, giving a good view of the superior petrosal sinus.' Gradual resolution of the abscess occurred, but a second mastoid exploration was necessary two years later to remove the sequestered facial ridge. A healthy mastoid cavity was eventually obtained, but the patient was left with a partial facial palsy. Case 4 This man received a course of radiotherapy in 1952 for bilateral otitis externa, which had proved unresponsive to conventional therapy. An orthovoltage unit was used, but the dose is not known. Worsening pain and foul, 950
Osteoradionecrosis of the temporal bone profuse otorrhoea developed gradually about five years after radiotherapy. Trismus became marked. Two mastoid explorations were carried out, at which the middle ear cleft was found to be filled with granulation and fibrous tissue. The superior and anteiior bony meatal walls had sequestered, as had part of the glenoid fossa, so that a communication existed between the middle ear and the temporomandibular joint. After the second sequestrectomy, the ear settled satisfactorily, but the patient was left with a profound sensorineural deafness and vertigo. Discussion
Normal mature bone is usually regarded as being relatively resistant to the harmful effects of radiotherapy and can be irradiated therapeutically with impunity (Lederman, 1965), a property which in part may be attributed to the filtering effects of the overlying soft tissue (Work, 1950). Those who treat intraoral malignancies, however, are well aware of the threat of radionecrosis of the mandible, an 'acceptable incidence' of which is stated by Rankow and Weissman (1971) to be 5 to 10 per cent. Several factors make the mandible more vulnerable to necrosis following radiotherapy: the close proximity of infected mouth or teeth, a relatively precarious blood supply (Dalley, 1973), and a superficial position which minimizes the soft tissue filtering effect at the same time as increasing the risk of direct trauma. The temporal bone, too, is superficially placed, protected only by the skin over the mastoid and the very thin skin of the external auditory meatus. It is in communication by way of the Eustachian tube with a potentially infected upper respiratory tract, and it appears that the blood supply of the tympanic ring at any rate is not good, as this is the part of the temporal bone most frequently seen to be involved in radionecrosis. Compact bone such as the temporal bone tolerates irradiation less well than cancellous bone, and this tolerance is further reduced when bone is invaded by neoplasm or is infected (Lederman, 1965). The need to deliver a cancericidal dose to bone invaded by new growth results in a greatly increased risk of radionecrosis (Schuknecht and Karmody, 1966). Pathogenesis: The underlying change in 'radiation osteitis' (Ewing, 1926) is aseptic avascular necrosis, the basis for which is the radiationinduced changes in the blood vessels supplying the bone. Ewing described a loss of vascularity resulting from obliterative endarteritis and periarteritis. Most elements in the vessel walls exhibit degenerative change, in particular smooth muscle and collagen, and the endothelium may so swell up as to narrow or even obliterate the lumen, increasing the risk of thrombus formation. At a late stage the vessels may atrophy or disappear or be replaced by a hyaline material (Gyorkey and Pollock, i960). Demineralization of bone occurs as osteolysis proceeds in the absence of any osteoblastic activity, and attempted repair occurs by fibrosis.
Richard T. Ramsden et al. Histologically there is an almost complete absence of osteocytes and osteoblasts, with empty lacunae, and a preponderance of osteoclasts, while spicules of dead bone may be surrounded by connective tissue (Schuknecht and Karmody, 1966). If infection is introduced, necrosis becomes more rapid. Ewing (1926) maintained that dead bone was a favourable site for bacteriological colinization by virtue of the protection offered by the Haversian system from leucocytic attack. This process continues slowly so that there may be a long latent period between irradiation and the onset of symptoms (in our series up to twenty-three years), a phenomenon which Ewing attributed to the slow metabolic turnover of bone compared with other tissues. Early symptoms such as otalgia or otorrhoea should lead one to suspect residual tumour, but we cannot agree with the statement of Bragg et al. (1970) that any change occurring after five years is more likely to be radiation sarcoma than osteonecrosis. It has been suggested (Woodard and Coley, 1947) that young people are better able to withstand the harmful effects of irradiation of bone than the old. We plotted the age of the patients at the time of radiotherapy against the latent period before osteonecrosis became evident (Table III). Although this is a small sample, it appears that patients under the age of 40 at the time of radiotherapy are unlikely to develop osteonecrosis in under eight years, whereas twelve of the twenty patients aged 40 and over had developed obvious necrosis within six years. If this is a valid observation, it suggests that the process of obliterative endarteritis is prolonged and continues long after the initial injury. A younger patient with a less precarious arterial tree may therefore take longer to reach the point of bone death. Nature of Irradiation: The degree of damage caused by radiotherapy is generally held to be in direct proportion to the dosage. The pertinent figure, however, is the dosage received by the tissues and not simply that emitted by the appliance in use. The former obviously depends upon the latter, but other factors, such as fractionation, filtering and field size, all influence the true figure. For this reason we have found it impossible to calculate the actual dose of radiation received by any one temporal bone and, although we have recorded the doses as they appeared in the case notes of the patients in this series, we have found them of little help in drawing conclusions. More important in establishing a dose relationship, is the occurrence of two distinct groups of patients: those with diffuse radionecrosis, in whom the temporal bone had been the prime target of irradiation, or at least close to the centre of the field, and, in contrast, the group with localized necrosis of the tympanic plate, a much less serious condition, the majority of whom had been irradiated for lesions at a distance from the ear, the temporal bone thus falling in the periphery of the irradiated field. The type of appliance used for irradiation is said to influence the 952
Osteoradionecrosis of the temporal bone incidence of osteoradionecrosis (Dalley, 1973). With 250 kv. orthovoltage the energy absorption by bone is two-and-a-half times that of soft tissue, whereas with megavoltage absorption by bone and soft tissue is equal (Meyer et al., 1962). One would, therefore, expect the incidence of this complication to be decreasing since the introduction of Co. 60 appliances, and to a certain extent this has happened (Bragg et al., 1970). Rankow and Weissman (1971), however, state that in their experience there has been no decrease in the incidence of osteoradionecrosis of the mandible with megavoltage. In our series of twenty-nine cases of the temporal bone, twelve had been treated by megavoltage, and of those twelve five suffered diffuse involvement; so, although in no way have we attempted to present a true incidence, it is apparent that radionecrosis of the temporal bone still does occur with megavoltage treatment. As the voltage of X-rays increases, so does the depth of penetration. Low (100 kv.) voltage units have little penetration and are used mainly for the treatment of superficial skin lesions. A Co 60 unit, however, produces its maximum effect (4 mm.) beneath the skin (Harrison, 1971). which is thus spared, but the underlying tissues receive the maximum dose. This may place a superficial bone (mandible or temporal bone) at added risk. The clinical picture in the localized type of disease is of otitis externa which may prove slow to resolve. Usually its true nature is recognized early in that the patient is attending a radiotherapy follow-up clinic. Where the original lesion has been a neoplasm of the middle or external ear, the alternative diagnosis of residual disease must be considered and any suspicious area biopsied. Occasionally, however, the diagnosis of osteonecrosis may elude the clinician for many weeks, during which he thinks he is merely dealing with a stubborn otitis externa. This is particularly likely if, as may happen, many years have elapsed since the radiotherapy. The patient may have fogotten a short course of treatment fifteen years previously for a small rodent ulcer on the cheek, or may not associate it with his present trouble. Case 4 illustrates the hazards of using radiotherapy for relatively trivial complaints, and it is worth bearing in mind that otitis externa, otosclerosis (Nylen, i960) Eustachian tube dysfunction and tinnitus have all been treated at some time by radiotherapy. Otititis externa which is proving resistant to conventional therapy, particularly in the presence of exposed or sequestering bone in the tympanic ring, should prompt the otologist to enquire about previous irradiation to the area. Conservative measures during the process of spontaneous sequestration are all that are required, after which healing may be expected, the whole process taking up to four years. Diffuse osteoradionecrosis of the temporal bone is a serious condition with a high risk of involvement of adjacent structures, particularly the 953
Richard T. Ramsden et al. facial nerve, labyrinth, lateral sinus, temporal lobe and cerebellum, and, less frequently, the parotid gland and temporo-mandibular joint. Severe pain and profuse offensive otorrhoea following radiotherapy are the clues to its presence, although the time interval between irradiation and the onset of necrosis may again cloud the issue. Treatment is surgical: early and radical exploration of the mastoid. Summary
A series of twenty-nine cases of osteoradionecrosis of the temporal bone is described. Two patterns occur: a localized involvement of the tympanic plate which resolves after the spontaneous separation of a sequestrum of bone, and a more diffuse necrosis of the temporal bone with a high risk of involvement of adjacent structures, in particular the brain, labyrinth and facial nerve and to a lesser extent the temporomandibular joint and the parotid gland. Localized osteonecrosis occurs more commonly when the temporal bone is in the periphery of an irradiated field whereas irradiation aimed primarily at the temporal bone is more likely to be followed by diffuse disease. The use of megavoltage irradiation has not lead to the disappearance of the complication which may occur as much as twenty years after the completion of the course of radiotherapy. Acknowledgements
We are grateful to those consultants from the Royal National Throat, Nose and Ear Hospital, St. Bartholomew's Hospital and The National Hospital for Nervous Diseases, London, and St. George's Hospital, Lincoln, who allowed us to report cases under their care, in particular, Mr. M. Spencer Harrison for his interest and help. We wish to thank the Photographic Departments of the Royal National Throat, Nose and Ear Hospital and St. Bartholomew's Hospital for the illustrations. REFERENCES BLOCK, E (1952) Zeitschrift fur Hals, Nase, und Ohrenheilkunde, 3, 45. BORSANYI, S (1962) Southern Medical Journal, 55, 740. BORSANYI, S., BLANCHARD, C. L., and THORNE, B. (1961) Annals of Otology, Rhin-
ology and Laryngology, 70, 255. BRAGG, D. G., SHIDNIA, H., CHU, F. C. H., and HIGINBOTHAM, N. L. (1970), Radi-
ology, 97, 103. DALLEY, V. M. (1973) In Recent Advances in Otolaryngology, 4th edition, Chapter 26, edited by J. Ransome, H. Holden and T. R. Bull. Churchill Livingstone, Edinburgh and London. EWING, J. (1926) Ada Radiologica 6, 400. GIRDEN, E. (1935) Journal of Comparative Psychology, 20, 263. GYORKEY, Z., and POLLOCK, F. J. (i960) Archives of Otolaryngology, 71, 793. HARRISON, D. F. N. (1971) In Scott-Brown's Diseases of the Ear, Nose and Throat, 3rd edition, volume 4, page 493, edited by J. Ballantyne and J. Groves, Butterworths, London.
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Osteoradionecrosis of the temporal bone KELEMEN, G. (1955) Archives of Otolaryngology, 61, 405. LEACH, W. (1965) Journal of Laryngology and Otology, 79, 870. LEDERMAN, M. (1965) Journal of Laryngology and Otology, 79, 85. MEYER, I., SHKLAR, G., and TURNER, J. (1962) Oral Surgery, 15, 1098.
NOVOTNY, O. (1951) Archivio Italiano di Otologia, Rinologia e Laryngologia, 62, 15. XYLEN, C. O. (1960) Ada Otolaryngologica, 51, 507. RAXKOW, R. M., and WEISSMAN, B. (1971) Annals of Otology, Rhinology and Laryngology, 80, 603. SCHUKNECHT, H. F. and KARMODY, C. S. (1966) Laryngoscope, 76, 1416.
WOODARD, H. Q., and COLEY, B. K. (1947) American Journal of Roentgenology, 57, 464. WORK, W. P. (1950) Annals of Otology, Rhinology and Laryngology, 59, 1062. E.X.T. Department, The London Hospital, Whitechapel, London El iBB.
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