Ann Otol Rhinol LaryngollOl:1992
IMAGING CASE STUDY OF THE MONTH
BONE SCAN DIAGNOSIS OF MASKED MASTOIDITIS ALBERT GATOT, MD
FERIT TOVI, MD BEER-SHEVA, ISRAEL
Inflammation of the mucosal lining of the mastoid air cells (mastoiditis) is a common condition. It occurs in all categories of otitis media because the middle ear cleft is a contiguous structure. Acute mastoiditis is a term coined to define osteitis in the partitions of the mastoid air cells. It may occur in the coalescent phase of acute otitis media and in chronic middle ear infections. 1.2 In both conditions the clinical picture is usually stormy. Another, atypical form of mastoiditis consists of a low-grade bone infection following an insidious course until the dramatic occurrence of intracranial or intratemporal complications.P:" Sometimes the disease is recognized only after the development of these complications. Early recognition is often difficult because both clinical and radiographic features are covert"; the disease is therefore frequently overlooked. The diagnosis of masked mastoiditis is suggested by signs and symptoms of acute mastoiditis with a virtually normal middle ear, the latter having responded to prior antibiotics. Sometimes diagnosis can be difficult to establish. The purpose of this report is to describe the role of bone scanning in turning the assumptive diagnosis into a confirmed one.
The middle ear appeared well aerated. Tissue swelling in the left postauricular area was present. A triphasic bone scan performed with technetium methylene diphosphonate (Tc-99 MDP) showed a mild activity of the isotope agent, at the blood pool phase, in the left mastoid area (see Figure, B). In the delayed phase, a moderate increase in the uptake of the isotope was detected in the same area (see Figure, C). A gallium-67 citrate (Ga-67) scan showed concentration of the isotope agent in the left temporal area. Osteitis was thereupon diagnosed. Intravenous cefuroxime sodium 100 mg/kg per day was initiated. At mastoidectomy the bone cortex was intact. Granulation tissue of the antrum and mesotympanum was cleaned and infected bony tissue was removed. The articular process of the incus was found to be necrotic. No pus was detected within the mastoid air cells. Intact wall tympanomastoidectomy was accomplished with incudostapediopexy and the reinforcement of the posterior aspect of the eardrum with a periosteal graft. The tympanostomy tube was preserved. The postoperative period was uneventful. Histologic examination of the removed mastoidectomy material showed chronic subepithelial inflammatory changes and osteitis. At follow-up the patient remained free of symptoms and a repeat Ga-67 scan was negative.
CASE STUDY
A 12-year-old boy was referred by the family physician because of left retroauricular pain, fever, and vomiting. He had a history of recurrent bouts of otitis media for which ventilation tubes had been previously inserted. Two months prior to the present admission he had been hospitalized because of similar complaints and treated by antibiotics.
DISCUSSION
The term masked mastoiditis refers to irreversible mucosal and bony changes within the mastoid and a middle ear with no particular abnormality. 3 The entity has been recognized since the introduction of antibiotics. This atypical mastoiditis, known also as silent otitis media, otitis-prone condition, or latent mastoiditis," occurs as a consequence of inadequate antimicrobial therapy in cases of acute otitis media." An insufficient course of therapy may provide a relief of the clinical symptoms and the middle ear may become aerated by the return of eustachian tube function. Yet, because of the obstruction of the tympanic diaphragm" by mucosal swelling, polypoid mucosa, or granulation tissue, a complete or incomplete separation of the tubotympanic cavity from the mastoid air cell system occurs. Accordingly, the latter remains unaerated and the local infectious mucosal process progresses into osteitis. Be-
On admission he was febrile (38°C). At physical examination the eardrum was found to be thickened. There was no discharge through the ventilation tube. The posterolateral wall of the ear canal was sagging and the post auricular area was mildly swollen and tender. The rest of the otorhinolaryngologic examination findings were normal and no neurologic deficit was detected. A routine blood cell count showed 11,000 white cells per cubic millimeter. An audiologic examination revealed a 50-dB air-bone gap in the left ear. Computed tomography (see Figure, A) of the temporal bone showed clouding of the left mastoid cells without bony changes.
From the Department of Otorhinolaryngology, Soroka Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
707
Downloaded from aor.sagepub.com at Oakland University on June 5, 2016
708
Tovi & Gatot, Imaging Case Study of the Month
Masked mastoiditis. A) Axial computed tomogram of temporal bone shows occlusion of left external ear canal, well-aerated middle ear, and clouding of mastoid air cells without bony changes. B) Posterior view of blood pool phase of bone scan demonstrates mild increase in isotope activity, laterally in left temporal bone. C) Delayed phase of bone scan images in posterior, anterior, and lateral display demonstrates moderate increase in technetium methylene diphosphonate uptake in left mastoid.
B
c
cause of the colonizing flora in this anaerobic condition, the developing bone infection is of a low grade" and the clinical features are not overt as are those of acute mastoiditis. Pain is minimal and fever is not high. The most striking aspect is that otoscopic findings do not reflect the serious nature of the bone-eroding mastoid disease. The eardrum may appear intact J 4 . , or may show a thickening or a mild inflammatory reaction. Even in the presence of a perforation, the middle ear lining does not show particular changes." Diverse intracranial, intratemporal, and at times distant complications may develop in these apparently innocent ears. 34.8.9 Plain x-ray film or computed tomographic scans in this case usually show only clouding of the mastoid air cells;':" corresponding to the thickening of the subepithelial layer in middle ear cleft infections.
The absence of marked bony changes in radiographic investigation is most probably due to lowgrade osteitis in which the bone destruction and demineralization are not as overt as those occurring in acute mastoiditis. For clear radiographic diagnosis of bone destruction, a large amount of bone matrix (30 % to 50 0/0) should have been destroyed or demineralized."? However, functional images provided by bone scan can indicate the osteoblastic respouse to an osteolytic process even when the marginating hypermineralization is low (about 5 0/0). \I Bone scan results are both quantitative and qualitative. This scan is highly sensitive but not specific. The isotope agent Tc-99 MDP concentrates in areas of osteogenesis; hence, it depicts the local metabolic bone activity secondary to infection, fracture, osteoblastic metastases, Paget's disease, or meningioma. ' ° When the nature of the insult is not clear,
Downloaded from aor.sagepub.com at Oakland University on June 5, 2016
Tovi & Gatot, Imaging Case Study of the Month
a positive Ga-67 scan may suggest an active infectious inflammatory process. However, Ga-67 positivity is not specific for infection; it can also occur in tumors.":" Multiple factors contribute to the accumulation of Ga-67 in inflammatory lesions. 13 An adequate blood supply is essential. Capillaries with increased permeability, in the area of inflammation, deliver this isotope in the form of transferrin-Ga-67 complex. At the same site some Ga-67 is also taken up by leukocytes and bacteria. In addition, the isotope may also bind to lactoferrin and bacterial siderophores. Accordingly, sequential use of Tc-99 MDP and Ga-67 scans brings a more precise diagnosis of active bone infection. In our case, the infectious inflammatory nature of the ear disease was clinically obvious. The Ga-67 scan was
709
performed in order to confirm it and also to establish a baseline for follow-up purposes. The mild increase in Tc-99 MDP activity at the blood pool phase, together with the moderate uptake of the isotope in the temporal bone at the delayed phase of the bone scan, was consistent with a low-grade bone infection. This was confirmed histologically. A high index of suspicion is necessary for the diagnosis of masked mastoiditis." A bone scan demonstrating the bone-invading nature of the mastoid infection is of paramount importance in the definitive diagnosis, as well as in the prompt treatment of the disease before catastrophic consequences develop.
REFERENCES 1. Shambaugh GE. Surgery of the ear. 2nd ed. Philadelphia, Pa: WB Saunders, 1967:187-224, 2, Shaffer HL, Gates GA, Meyerhoff WL. Acute mastoiditis and cholesteatoma. Otolaryngol Head Neck Surg 1978;86:394-9, 3, Holt GR, Gates GA. Masked mastoiditis, Laryngoscope 1983;93: 1034-7.
8, Tovi F, Hirsch M, Gatot A, Superior vena cava syndrome: presenting symptom of silent otitis media, J Laryngol Otol 1988; 102:623-5, 9. Tovi F, Leiberman A. Silent mastoiditis and bilateral simultaneous facial palsy. Int J Pediatr Otorhinolaryngol 1983;5: 303-7.
4, Samuel J, Fernandes CMC. Otogenic complications with an intact tympanic membrane, Laryngoscope 1985;95:1387-90.
10. Noyek AM, Bone scanning in otolaryngology. Laryngoscope 1979;89(suppl 18).
5, Mawson S, Acute inflammation of the middle ear cleft, In: Ballantyne J, Groves J, eds. Scott-Brown's Diseases of the ear, nose and throat, 4th ed. Vol 1. London, England: Butterworths, 1979:175-92,
11. Noyek AM, Kirsh JC, Greyson ND, et al. The clinical significance of radionuclide bone and gallium scanning in osteomyelitis of the head and neck. Laryngoscope 1984;94(suppl 34).
6, Proctor B, Attic-aditus block and the tympanic diaphragm, Ann Otol Rhinol Laryngol 1971;80:371-5,
12. Estes DN, Magill HL, Thompson El , Hayes FA, Primary Ewing sarcoma: follow-up with Ga-67 scintigraphy. Radiology 1990;177 :449-53,
7, Rosen A, Ophir D, Marshak G, Acute mastoiditis: a review of 69 cases. Ann Otol Rhinol Laryngol 1986;95:222-4.
13. Tsan MF, Mechanism of gallium-67 accumulation in inflammatory lesions, J Nucl Med 1985;26:88-92.
AMERICAN AUDITORY SOCIETY, INC The 19th annual meeting of the American Auditory Society, Inc, will be held November 19, 1992, in San Antonio, Texas. For further information, contact Don W. Worthington, PhD, Chair, AAS Program Committee, Boys Town National Institute, 555 North 30th Street, Omaha, NE 68131.
Downloaded from aor.sagepub.com at Oakland University on June 5, 2016
IMAGING CASE STUDY OF THE MONTH
BONE SCAN DIAGNOSIS OF MASKED MASTOIDITIS ALBERT GATOT, MD
FERIT TOVI, MD BEER-SHEVA, ISRAEL
Inflammation of the mucosal lining of the mastoid air cells (mastoiditis) is a common condition. It occurs in all categories of otitis media because the middle ear cleft is a contiguous structure. Acute mastoiditis is a term coined to define osteitis in the partitions of the mastoid air cells. It may occur in the coalescent phase of acute otitis media and in chronic middle ear infections. 1.2 In both conditions the clinical picture is usually stormy. Another, atypical form of mastoiditis consists of a low-grade bone infection following an insidious course until the dramatic occurrence of intracranial or intratemporal complications.P:" Sometimes the disease is recognized only after the development of these complications. Early recognition is often difficult because both clinical and radiographic features are covert"; the disease is therefore frequently overlooked. The diagnosis of masked mastoiditis is suggested by signs and symptoms of acute mastoiditis with a virtually normal middle ear, the latter having responded to prior antibiotics. Sometimes diagnosis can be difficult to establish. The purpose of this report is to describe the role of bone scanning in turning the assumptive diagnosis into a confirmed one.
The middle ear appeared well aerated. Tissue swelling in the left postauricular area was present. A triphasic bone scan performed with technetium methylene diphosphonate (Tc-99 MDP) showed a mild activity of the isotope agent, at the blood pool phase, in the left mastoid area (see Figure, B). In the delayed phase, a moderate increase in the uptake of the isotope was detected in the same area (see Figure, C). A gallium-67 citrate (Ga-67) scan showed concentration of the isotope agent in the left temporal area. Osteitis was thereupon diagnosed. Intravenous cefuroxime sodium 100 mg/kg per day was initiated. At mastoidectomy the bone cortex was intact. Granulation tissue of the antrum and mesotympanum was cleaned and infected bony tissue was removed. The articular process of the incus was found to be necrotic. No pus was detected within the mastoid air cells. Intact wall tympanomastoidectomy was accomplished with incudostapediopexy and the reinforcement of the posterior aspect of the eardrum with a periosteal graft. The tympanostomy tube was preserved. The postoperative period was uneventful. Histologic examination of the removed mastoidectomy material showed chronic subepithelial inflammatory changes and osteitis. At follow-up the patient remained free of symptoms and a repeat Ga-67 scan was negative.
CASE STUDY
A 12-year-old boy was referred by the family physician because of left retroauricular pain, fever, and vomiting. He had a history of recurrent bouts of otitis media for which ventilation tubes had been previously inserted. Two months prior to the present admission he had been hospitalized because of similar complaints and treated by antibiotics.
DISCUSSION
The term masked mastoiditis refers to irreversible mucosal and bony changes within the mastoid and a middle ear with no particular abnormality. 3 The entity has been recognized since the introduction of antibiotics. This atypical mastoiditis, known also as silent otitis media, otitis-prone condition, or latent mastoiditis," occurs as a consequence of inadequate antimicrobial therapy in cases of acute otitis media." An insufficient course of therapy may provide a relief of the clinical symptoms and the middle ear may become aerated by the return of eustachian tube function. Yet, because of the obstruction of the tympanic diaphragm" by mucosal swelling, polypoid mucosa, or granulation tissue, a complete or incomplete separation of the tubotympanic cavity from the mastoid air cell system occurs. Accordingly, the latter remains unaerated and the local infectious mucosal process progresses into osteitis. Be-
On admission he was febrile (38°C). At physical examination the eardrum was found to be thickened. There was no discharge through the ventilation tube. The posterolateral wall of the ear canal was sagging and the post auricular area was mildly swollen and tender. The rest of the otorhinolaryngologic examination findings were normal and no neurologic deficit was detected. A routine blood cell count showed 11,000 white cells per cubic millimeter. An audiologic examination revealed a 50-dB air-bone gap in the left ear. Computed tomography (see Figure, A) of the temporal bone showed clouding of the left mastoid cells without bony changes.
From the Department of Otorhinolaryngology, Soroka Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
707
Downloaded from aor.sagepub.com at Oakland University on June 5, 2016
708
Tovi & Gatot, Imaging Case Study of the Month
Masked mastoiditis. A) Axial computed tomogram of temporal bone shows occlusion of left external ear canal, well-aerated middle ear, and clouding of mastoid air cells without bony changes. B) Posterior view of blood pool phase of bone scan demonstrates mild increase in isotope activity, laterally in left temporal bone. C) Delayed phase of bone scan images in posterior, anterior, and lateral display demonstrates moderate increase in technetium methylene diphosphonate uptake in left mastoid.
B
c
cause of the colonizing flora in this anaerobic condition, the developing bone infection is of a low grade" and the clinical features are not overt as are those of acute mastoiditis. Pain is minimal and fever is not high. The most striking aspect is that otoscopic findings do not reflect the serious nature of the bone-eroding mastoid disease. The eardrum may appear intact J 4 . , or may show a thickening or a mild inflammatory reaction. Even in the presence of a perforation, the middle ear lining does not show particular changes." Diverse intracranial, intratemporal, and at times distant complications may develop in these apparently innocent ears. 34.8.9 Plain x-ray film or computed tomographic scans in this case usually show only clouding of the mastoid air cells;':" corresponding to the thickening of the subepithelial layer in middle ear cleft infections.
The absence of marked bony changes in radiographic investigation is most probably due to lowgrade osteitis in which the bone destruction and demineralization are not as overt as those occurring in acute mastoiditis. For clear radiographic diagnosis of bone destruction, a large amount of bone matrix (30 % to 50 0/0) should have been destroyed or demineralized."? However, functional images provided by bone scan can indicate the osteoblastic respouse to an osteolytic process even when the marginating hypermineralization is low (about 5 0/0). \I Bone scan results are both quantitative and qualitative. This scan is highly sensitive but not specific. The isotope agent Tc-99 MDP concentrates in areas of osteogenesis; hence, it depicts the local metabolic bone activity secondary to infection, fracture, osteoblastic metastases, Paget's disease, or meningioma. ' ° When the nature of the insult is not clear,
Downloaded from aor.sagepub.com at Oakland University on June 5, 2016
Tovi & Gatot, Imaging Case Study of the Month
a positive Ga-67 scan may suggest an active infectious inflammatory process. However, Ga-67 positivity is not specific for infection; it can also occur in tumors.":" Multiple factors contribute to the accumulation of Ga-67 in inflammatory lesions. 13 An adequate blood supply is essential. Capillaries with increased permeability, in the area of inflammation, deliver this isotope in the form of transferrin-Ga-67 complex. At the same site some Ga-67 is also taken up by leukocytes and bacteria. In addition, the isotope may also bind to lactoferrin and bacterial siderophores. Accordingly, sequential use of Tc-99 MDP and Ga-67 scans brings a more precise diagnosis of active bone infection. In our case, the infectious inflammatory nature of the ear disease was clinically obvious. The Ga-67 scan was
709
performed in order to confirm it and also to establish a baseline for follow-up purposes. The mild increase in Tc-99 MDP activity at the blood pool phase, together with the moderate uptake of the isotope in the temporal bone at the delayed phase of the bone scan, was consistent with a low-grade bone infection. This was confirmed histologically. A high index of suspicion is necessary for the diagnosis of masked mastoiditis." A bone scan demonstrating the bone-invading nature of the mastoid infection is of paramount importance in the definitive diagnosis, as well as in the prompt treatment of the disease before catastrophic consequences develop.
REFERENCES 1. Shambaugh GE. Surgery of the ear. 2nd ed. Philadelphia, Pa: WB Saunders, 1967:187-224, 2, Shaffer HL, Gates GA, Meyerhoff WL. Acute mastoiditis and cholesteatoma. Otolaryngol Head Neck Surg 1978;86:394-9, 3, Holt GR, Gates GA. Masked mastoiditis, Laryngoscope 1983;93: 1034-7.
8, Tovi F, Hirsch M, Gatot A, Superior vena cava syndrome: presenting symptom of silent otitis media, J Laryngol Otol 1988; 102:623-5, 9. Tovi F, Leiberman A. Silent mastoiditis and bilateral simultaneous facial palsy. Int J Pediatr Otorhinolaryngol 1983;5: 303-7.
4, Samuel J, Fernandes CMC. Otogenic complications with an intact tympanic membrane, Laryngoscope 1985;95:1387-90.
10. Noyek AM, Bone scanning in otolaryngology. Laryngoscope 1979;89(suppl 18).
5, Mawson S, Acute inflammation of the middle ear cleft, In: Ballantyne J, Groves J, eds. Scott-Brown's Diseases of the ear, nose and throat, 4th ed. Vol 1. London, England: Butterworths, 1979:175-92,
11. Noyek AM, Kirsh JC, Greyson ND, et al. The clinical significance of radionuclide bone and gallium scanning in osteomyelitis of the head and neck. Laryngoscope 1984;94(suppl 34).
6, Proctor B, Attic-aditus block and the tympanic diaphragm, Ann Otol Rhinol Laryngol 1971;80:371-5,
12. Estes DN, Magill HL, Thompson El , Hayes FA, Primary Ewing sarcoma: follow-up with Ga-67 scintigraphy. Radiology 1990;177 :449-53,
7, Rosen A, Ophir D, Marshak G, Acute mastoiditis: a review of 69 cases. Ann Otol Rhinol Laryngol 1986;95:222-4.
13. Tsan MF, Mechanism of gallium-67 accumulation in inflammatory lesions, J Nucl Med 1985;26:88-92.
AMERICAN AUDITORY SOCIETY, INC The 19th annual meeting of the American Auditory Society, Inc, will be held November 19, 1992, in San Antonio, Texas. For further information, contact Don W. Worthington, PhD, Chair, AAS Program Committee, Boys Town National Institute, 555 North 30th Street, Omaha, NE 68131.
Downloaded from aor.sagepub.com at Oakland University on June 5, 2016
