CERVICAL SPONDYLOTIC MYELOPATHY: A COOPERATIVE STUDY
Luis Gonz6lez-Feria and Pablo Peraita-Peraita*
SUMMARY A series of 521 cases of CSM in 22 clinics in Spain and Portugal were studied. The severity of the clinical picture, both before and after the operations, was graded following a six point scale (a modification of Nurick's). The operations the patients underwent were classified into eight types and their results expressed by using the same scale. Some improvement has been attained in all grades of myelopathy with all types of operations, but better results, especially in advanced cases, have been obtained when surgical fixation of the spine, as well as laminectomy, has been carried out. A number of different surgical techniques have been used, and are still in use, for the treatment of Cervical Spondylotic Myelopathy (CSM). The rationale of these techniques has changed according the changing ideas about the pathogenesis of the disease. For many years the aim of surgery was decompression of the canal by laminectomy; then the removal of the osteophytes was advocated in some cases; later a pathogenic role of the dentate ligaments was suggested and their section recommended; some authors advocated leaving the dura mater open while others preferred the opposite; facetectomy and foraminotomy might improve the results of surgery; the anterior approach seemed to be more physiological and different techniques were introduced simultaneously; the possibility of removal of the osteophytes by a postero-lateral approach has been shown; recently, the very aggressive medial longitudinal somatotomy has been described and the more conservative cervicolordodesis suggested (KAHN 1947; ALLEN 1952; CLOWARO 1958; ROGERS 1961; SCOVILLE 1961; DEREYMAKER, GHOSEZ and HENKES 1963; EPSTEIN CARRAS, LAVINE and EPSTEIN 1969; VERBIEST 1970; FRYKHOLM 1971; JEFFERSON 1971; PANSINI and LORE 1972; BREIG 1973). As Jefferson stated 'when there are very many methods for the treatment of a single condition, one knows immediately that it is difficult to treat'. Undoubtedly, the surgical treatment of CSM is, at present, controversial. At the request of the Sociedad Luso-Espafiola de Neurocirugfa, a cooperative * Neurosurgical Service. Hospital General. University of La Laguna (Tenerife), and Neurosurgical Service, Ciudad Sanitaria Francisco Franco (Madrid). Spain. Clin. Neurol. Neurosurg. 1975-1
20 study has been made in order to find out which surgical techniques are being used in Spain and Portugal, their results, and the factors which can be related to these results.
METHODS A questionnaire was sent out, and in all, a sample of 521 cases was returned by the 22 neurosurgical clinics who collaborated with us. This sample was then analysed with the help of the biostatisticians of the University of La Laguna (Canarias). The computed factors were: 1) age and sex of the patient; 2) length of the history prior to operation; 3) 'congenital' and 'acquired' bony diameters of the cervical spinal canal; 4) number and levels of compression of the spinal cord; 5) results of manometric studies; 6) grade of myelopathy before and after the operation; 7) type of operation and 8) operative results. Some of these factors need some comments. The 'congenital' diameter of the canal was measured from the midpoint of the posterior aspect of the vertebral body to the anterior face of the corresponding laminae; the 'acquired' diameter, that is to say, the narrowest diameter of the canal, was measured from the top of the osteophitic bars to the nearest point of the laminae. The number and level of compression were taken from both, the data obtained from plain X rays and from myelographic studies. Regarding preoperative and postoperative grade of myelopathy, all patients had a neurological picture, usually a spastic para or tetraparesis, with or without sensory changes. Since this picture often changes after operation only in a quantitative (but not a qualitative) sense, the point was to choose a quantitative method for evaluation of the neurological deficit. At the start of this work we had two alternative methods; either to use the score system for the different neurological deficits, or to use a simple distribution of the material attending to the patients' ability to work or to take care of themselves. The first alternative was discarded for obvious reasons (retroactive evaluation of a large material), and we chose Nurick's recent classification (NURICK 1972), slightly modified: Grades Grade Grade Grade Grade
of 0: 1: 2: 3:
myelopathy No evidence of spinal cord disease. Signs of spinal cord disease but no difficulty in walking. Slight difficulty in walking which does not prevent fulltime employment. Difficulty in walking which allows part time employment, another type of work, or house work. Grade 4: Difficulty in walking which prevents all employment or house work, but which is not so severe as to require someone else's help in order to walk.
21 Grade 5: Able to walk only with someone else's help or with the aid of a frame. Grade 6: Unable to walk or bedridden. Grades 1, 2 and 3 are mild forms, and grades 4, 5 and 6 more advanced forms of myelopathy. Regarding the type of operation, four main types and several subgroups of operative techniques were differentiated (see below) and finally, the results of operations have been evaluated using the same six point scale as prior to operation.
RESULTS AND DISCUSSION
Age: (Fig. 1) The analysis of the series show that in the group of operated patients, the disease is diagnosed most often in middle age thus corroborating most reports. If the disease is considered a degenerative one, it seems to be a contradic-
CSM 521 CASES 101 92 88
9O
46
45 35
27
6
I 3O
40
50
60
70
DISTRIBUTION OF PATIENTS BY A G E fig. 1 tion that there are fewer cases diagnosed in the older age groups. If the curves are corrected assuming that every age group contains a similar population, the histogram is still very similar (Fig. 2). This means that there must be other explanations, for instance, diagnostic failures in the elderly, or non operation, or finally that the disease really does occur less frequently in the older age groups. If the latter is accepted, further explanations may be suggested, for example, an atrophy
22
CSM
30
40
5O
60
70
DISTRIBUTION BY A G E CORRECTED AGE ,GROUPS
fig. 2
of the cord through age that prevents compression from occurring (Gilland and Stockhaus-Aberg 1965), or limitation of movements of the neck brought about by an increasing spondylosis, or some other unknown factor that comes into play in middle age. Sex: (Fig. 3) It is well known from the literature that there is a higher incidence of cases among men. In our material the same is true. It is an intriguing fact with no clear explanation. It has been suggested that an occupational factor could account for it. It seems reasonable that heavy work predisposes to spondylotic changes of the spine but it is difficult to say if it can account for this extreme sex difference. Length of the history prior to operation: The material is distributed as shown in Fig. 4. More than half the patients had had the disease for more than one year and as many as 48 had had symptoms for more than 6 years. Patients with a very" short history, of less than one month, were only 6 in number. 'Congenital' and 'acquired' bony diameter of the spinal canal: No doubt, the size of the osteophytes plays a role in the compression of the cord, but the importance of this factor is closely related to the so called 'congenital' diameter of the spinal canal. It has been shown by several authors that the mean value of this di-
23
CSM 432 62.9%
90 70
76
76
37
29 [ 23 J-'-] 30
89
40
[20. 3 50
18 16
60
70
14
17.1% DISTRIBUTION BY SEX AND AGE
fig. 3
ameter (at the lower 4 cervical levels) is about 13 mm. for patients with myelopathy and about 16-17 mm. for non myelopathic conditions or healthy people (MAYFIELD 1955; WOLF, K[-IILNANIand MALLS, 1956; NUGENT 1959; HINCK and SACHDEV 1966; PENNING 1968). The 'acquired' diameter is always smaller. In our series the diameters were reported in 390 cases (74.8% of the total). Their distribution and mean values are shown in Fig. 5. In Fig. 6 the mean values of the diameters in the normal population and in myelopathy cases are represented in a very schematic form. Levels o/ compression: Myelography was performed before operation in every reported case, in 9 7 % of the cases using oil as contrast media. We determined the probable levels of compression from the data obtained from myelographies and from the measurements of the canal in neutral position of neck. It soon became evident that these data were very unreliable because the levels of compression depend also on dynamic factors that were not taken into account in most of the cases. For this reason they were given a limited value in our study. In Fig. 7 num-
24
133
CSM
22"
ACQUIRED DIAMETER M E A N VALUE 9.Smm
CSM
130 -
~=
120 -
CONGENITAL DIAMETER MEAN VALUE 12.5rnm
110 -
64 r~
qlW
10090-
8070-
60-
q
50-
:: F
6 1 -
6
2-3 3-6 6"-121-3 3-6 > 6 months
== years---~
LENGTH
OF
[ ] MALE
[ ] FEMALE
7
8
9
10 11 12 13 14 15 16
rnrn
"CONGENITAl." AND "ACQUIRED" BONY DIAMETERS
fig. 5
HISTORY
fig. 4
bet and situation of the affected levels are represented. Obviously the small number reported at the C7-T1 level is due to its poor X ray visibility. Unfortunately, dynamic studies in our material are rather few, and the incidence of the pincer mechanism could not be analysed (PENNING 1968). Perhaps it would be worthwhile, for all cases of suspected myelopathy, to be studied routinely, with a radiological technique that allows both measurements of the canal and the recognition of dynamic skeletal factors. This is important not only for a correct diagnosis but also in order to plan proper surgery. Here we would point out the striking coincidence between the levels of compression observed in myelography and those observed in plain X rays.
25 CSM
3 17
NORMAL CASES
MYELOPATHY CASES
MEAN VALUES OF SAGITTAL BONY DIAMETERS fig. 6
Spinal manometry: Spinal manometry has been used in a limited number of cases (Table I). Using the standard open and manometry (neck in neutral position only), slightly more than 50% of the readings gave abnormal results, with a partial or total block.
CSM
0/
/2 3
110
4
195
5
345
6 214
frll 4 TOTAL NUMBER OF AFFECTED LEVELS fig. 7
26 TABLE I
Preoperative 'standard' manometry 137 cases (26.2~) Degree of block Normal Partial block Total block
Position of the neck Neutral 46~ 33~ 21%
Dynamic manometric studies (KAPLAN and KENNEDY 1950; GILLAND1962) have been still less common; only 8% (Table II). In many of these cases, the technique proposed by Gilland using the so called 'Optodynamic Fluid Manometer' has been used (GILLAND 1965). This is an open end, but sensitive, method of manometry that allows reliable measurements even in cases of partial block. In these series, the degree of block increases in the extension of the neck, so that only 15% of the cases showed a normal passage of the fluid. T A B L E 11
Preoperative dynamic manometry 45 cases (8.6 ~) Degree of block Normal Partial block Total block
Position of the neck Neutral Flexion 46 ~ 50 ~ 33 ~ 36 ~ 21% 14%
Extension 15 27 58~
Electromanometry (Table III) has been used on only 16 patients by one of us (LGF). We have followed the technique proposed by Gilland (1962) and found Lakke's book 'The Queckenstedt's test' useful in interpreting the results. The patients in our series of electromanometries occasionally had an advanced clinical picture. This is perhaps the cause of the high proportion of blocks that in extension rcaches the figure of 100%. These patients improved more with operation than average groups did. This is in agreement with the observations of Lakke, who found that patients with an electromanometric block reacted better to operation than those without. T A B L E 111
Preoperative 'electromanometry' 16 cases (3 ~), all grades of myelopathy 4, 5 and 6 Degree of block Position of the neck Neutral Flexion Extension Normal 25 ~ 31 ~ 0 Partial block 44 ~ 50 ~ 19 Total block 31 ~ 19~ 81
27
Preoperative grade of myelopathy: Fig. 8 shows the distribution of the cases by the grade of myelopathy before operation. There are more cases in the intermediate groups but there are quite a few even in the more advanced categories. ),-
-r
CSM
61
158 It,, u-o o
uJ ,,,~r
a:~ OtD
152 127
4 5
70
149
6
NUMBER OF PATIENTS fig. 8
Type o[ operation: The different types of operations have been classified in four groups and six subgroups (Table IV). All groups but one ('large laminectomy') contain a large enough sample for statistical purposes. The anterior approach has been analysed depending on whether the patients were operated at one, two or more than two levels. Laminectomy patients were divided into three groups depending on the size of the laminectomy. T A B L E IV
Type of operation and number of patients Type of operation ~l levels Anterior approach "2 levels f3-4 levels ~small Laminectomy )medium '~ large Laminectomy ÷ ant. approach Laminectomy + post. fixation
Number 121 55 19 95 141 6 42 41
of cases and 23.3 ~ ) 10.5 ~ ~195 3.6 ~/' 18.3~ 27.2~ t242 ! .2 ~ t 8.1% 7.9~
37,5~ 46.6
The group operated by both, anterior and posterior approach in two seances, includes all cases regardless of which type of operation was performed first. The fourth group needs some comments. Patients in this group have been operated with medium sized laminectomy, followed by a posterior fixation, in most instances with the help of a metal plate. The rationale of the procedure and its results, have been published elsewhere (GONZ~LEZ-FER[A 1975). Results of operations: The overall results are shown in figure 9. In the middle of the figure are the unchanged cases, 33°/o. Nearly 60°/o of the patients improved
28 1.7'/. + 4
CSM
I
73% I,-Z
u.I t,O
: ÷
0.9
17.5°/0 ÷
2
÷
1
o
n,, Q.
IMPROVEMENT
AVERAGE
.3
33% 33%
~
59.5%
Z O n~
"
+'lJ
-I
-2
1%
o uJ I.-
6.5%
-3
1%
UJ (3
-4
RESULTS
q2"/.
fig. 9
and 6,51)/0 deteriorated. Mortality has not been represented in this figure, but that were 16 cases, i.e. 3 % of the 521 operated cases. In about half of the cases, death was due to causes related to operation. The average improvement for the whole material is 0.9 grades of the scale. The analysis of the results taking into account the grade of myelopathy before operation and the type of operation is shown in Table V. The ordinate represents ANT.
LAMIN- LAM +
LAM +
APPR ECTOIvftANT.AP FI X.
0.5 33
1.0 27
0.4 19
0.8 22
1o+ , o
O0
0
0.7
1.5
3
2
10 10
, ~ t.kl
o_
4
o w wn,"
5
0
O
Luis Gonz6lez-Feria and Pablo Peraita-Peraita*
SUMMARY A series of 521 cases of CSM in 22 clinics in Spain and Portugal were studied. The severity of the clinical picture, both before and after the operations, was graded following a six point scale (a modification of Nurick's). The operations the patients underwent were classified into eight types and their results expressed by using the same scale. Some improvement has been attained in all grades of myelopathy with all types of operations, but better results, especially in advanced cases, have been obtained when surgical fixation of the spine, as well as laminectomy, has been carried out. A number of different surgical techniques have been used, and are still in use, for the treatment of Cervical Spondylotic Myelopathy (CSM). The rationale of these techniques has changed according the changing ideas about the pathogenesis of the disease. For many years the aim of surgery was decompression of the canal by laminectomy; then the removal of the osteophytes was advocated in some cases; later a pathogenic role of the dentate ligaments was suggested and their section recommended; some authors advocated leaving the dura mater open while others preferred the opposite; facetectomy and foraminotomy might improve the results of surgery; the anterior approach seemed to be more physiological and different techniques were introduced simultaneously; the possibility of removal of the osteophytes by a postero-lateral approach has been shown; recently, the very aggressive medial longitudinal somatotomy has been described and the more conservative cervicolordodesis suggested (KAHN 1947; ALLEN 1952; CLOWARO 1958; ROGERS 1961; SCOVILLE 1961; DEREYMAKER, GHOSEZ and HENKES 1963; EPSTEIN CARRAS, LAVINE and EPSTEIN 1969; VERBIEST 1970; FRYKHOLM 1971; JEFFERSON 1971; PANSINI and LORE 1972; BREIG 1973). As Jefferson stated 'when there are very many methods for the treatment of a single condition, one knows immediately that it is difficult to treat'. Undoubtedly, the surgical treatment of CSM is, at present, controversial. At the request of the Sociedad Luso-Espafiola de Neurocirugfa, a cooperative * Neurosurgical Service. Hospital General. University of La Laguna (Tenerife), and Neurosurgical Service, Ciudad Sanitaria Francisco Franco (Madrid). Spain. Clin. Neurol. Neurosurg. 1975-1
20 study has been made in order to find out which surgical techniques are being used in Spain and Portugal, their results, and the factors which can be related to these results.
METHODS A questionnaire was sent out, and in all, a sample of 521 cases was returned by the 22 neurosurgical clinics who collaborated with us. This sample was then analysed with the help of the biostatisticians of the University of La Laguna (Canarias). The computed factors were: 1) age and sex of the patient; 2) length of the history prior to operation; 3) 'congenital' and 'acquired' bony diameters of the cervical spinal canal; 4) number and levels of compression of the spinal cord; 5) results of manometric studies; 6) grade of myelopathy before and after the operation; 7) type of operation and 8) operative results. Some of these factors need some comments. The 'congenital' diameter of the canal was measured from the midpoint of the posterior aspect of the vertebral body to the anterior face of the corresponding laminae; the 'acquired' diameter, that is to say, the narrowest diameter of the canal, was measured from the top of the osteophitic bars to the nearest point of the laminae. The number and level of compression were taken from both, the data obtained from plain X rays and from myelographic studies. Regarding preoperative and postoperative grade of myelopathy, all patients had a neurological picture, usually a spastic para or tetraparesis, with or without sensory changes. Since this picture often changes after operation only in a quantitative (but not a qualitative) sense, the point was to choose a quantitative method for evaluation of the neurological deficit. At the start of this work we had two alternative methods; either to use the score system for the different neurological deficits, or to use a simple distribution of the material attending to the patients' ability to work or to take care of themselves. The first alternative was discarded for obvious reasons (retroactive evaluation of a large material), and we chose Nurick's recent classification (NURICK 1972), slightly modified: Grades Grade Grade Grade Grade
of 0: 1: 2: 3:
myelopathy No evidence of spinal cord disease. Signs of spinal cord disease but no difficulty in walking. Slight difficulty in walking which does not prevent fulltime employment. Difficulty in walking which allows part time employment, another type of work, or house work. Grade 4: Difficulty in walking which prevents all employment or house work, but which is not so severe as to require someone else's help in order to walk.
21 Grade 5: Able to walk only with someone else's help or with the aid of a frame. Grade 6: Unable to walk or bedridden. Grades 1, 2 and 3 are mild forms, and grades 4, 5 and 6 more advanced forms of myelopathy. Regarding the type of operation, four main types and several subgroups of operative techniques were differentiated (see below) and finally, the results of operations have been evaluated using the same six point scale as prior to operation.
RESULTS AND DISCUSSION
Age: (Fig. 1) The analysis of the series show that in the group of operated patients, the disease is diagnosed most often in middle age thus corroborating most reports. If the disease is considered a degenerative one, it seems to be a contradic-
CSM 521 CASES 101 92 88
9O
46
45 35
27
6
I 3O
40
50
60
70
DISTRIBUTION OF PATIENTS BY A G E fig. 1 tion that there are fewer cases diagnosed in the older age groups. If the curves are corrected assuming that every age group contains a similar population, the histogram is still very similar (Fig. 2). This means that there must be other explanations, for instance, diagnostic failures in the elderly, or non operation, or finally that the disease really does occur less frequently in the older age groups. If the latter is accepted, further explanations may be suggested, for example, an atrophy
22
CSM
30
40
5O
60
70
DISTRIBUTION BY A G E CORRECTED AGE ,GROUPS
fig. 2
of the cord through age that prevents compression from occurring (Gilland and Stockhaus-Aberg 1965), or limitation of movements of the neck brought about by an increasing spondylosis, or some other unknown factor that comes into play in middle age. Sex: (Fig. 3) It is well known from the literature that there is a higher incidence of cases among men. In our material the same is true. It is an intriguing fact with no clear explanation. It has been suggested that an occupational factor could account for it. It seems reasonable that heavy work predisposes to spondylotic changes of the spine but it is difficult to say if it can account for this extreme sex difference. Length of the history prior to operation: The material is distributed as shown in Fig. 4. More than half the patients had had the disease for more than one year and as many as 48 had had symptoms for more than 6 years. Patients with a very" short history, of less than one month, were only 6 in number. 'Congenital' and 'acquired' bony diameter of the spinal canal: No doubt, the size of the osteophytes plays a role in the compression of the cord, but the importance of this factor is closely related to the so called 'congenital' diameter of the spinal canal. It has been shown by several authors that the mean value of this di-
23
CSM 432 62.9%
90 70
76
76
37
29 [ 23 J-'-] 30
89
40
[20. 3 50
18 16
60
70
14
17.1% DISTRIBUTION BY SEX AND AGE
fig. 3
ameter (at the lower 4 cervical levels) is about 13 mm. for patients with myelopathy and about 16-17 mm. for non myelopathic conditions or healthy people (MAYFIELD 1955; WOLF, K[-IILNANIand MALLS, 1956; NUGENT 1959; HINCK and SACHDEV 1966; PENNING 1968). The 'acquired' diameter is always smaller. In our series the diameters were reported in 390 cases (74.8% of the total). Their distribution and mean values are shown in Fig. 5. In Fig. 6 the mean values of the diameters in the normal population and in myelopathy cases are represented in a very schematic form. Levels o/ compression: Myelography was performed before operation in every reported case, in 9 7 % of the cases using oil as contrast media. We determined the probable levels of compression from the data obtained from myelographies and from the measurements of the canal in neutral position of neck. It soon became evident that these data were very unreliable because the levels of compression depend also on dynamic factors that were not taken into account in most of the cases. For this reason they were given a limited value in our study. In Fig. 7 num-
24
133
CSM
22"
ACQUIRED DIAMETER M E A N VALUE 9.Smm
CSM
130 -
~=
120 -
CONGENITAL DIAMETER MEAN VALUE 12.5rnm
110 -
64 r~
qlW
10090-
8070-
60-
q
50-
:: F
6 1 -
6
2-3 3-6 6"-121-3 3-6 > 6 months
== years---~
LENGTH
OF
[ ] MALE
[ ] FEMALE
7
8
9
10 11 12 13 14 15 16
rnrn
"CONGENITAl." AND "ACQUIRED" BONY DIAMETERS
fig. 5
HISTORY
fig. 4
bet and situation of the affected levels are represented. Obviously the small number reported at the C7-T1 level is due to its poor X ray visibility. Unfortunately, dynamic studies in our material are rather few, and the incidence of the pincer mechanism could not be analysed (PENNING 1968). Perhaps it would be worthwhile, for all cases of suspected myelopathy, to be studied routinely, with a radiological technique that allows both measurements of the canal and the recognition of dynamic skeletal factors. This is important not only for a correct diagnosis but also in order to plan proper surgery. Here we would point out the striking coincidence between the levels of compression observed in myelography and those observed in plain X rays.
25 CSM
3 17
NORMAL CASES
MYELOPATHY CASES
MEAN VALUES OF SAGITTAL BONY DIAMETERS fig. 6
Spinal manometry: Spinal manometry has been used in a limited number of cases (Table I). Using the standard open and manometry (neck in neutral position only), slightly more than 50% of the readings gave abnormal results, with a partial or total block.
CSM
0/
/2 3
110
4
195
5
345
6 214
frll 4 TOTAL NUMBER OF AFFECTED LEVELS fig. 7
26 TABLE I
Preoperative 'standard' manometry 137 cases (26.2~) Degree of block Normal Partial block Total block
Position of the neck Neutral 46~ 33~ 21%
Dynamic manometric studies (KAPLAN and KENNEDY 1950; GILLAND1962) have been still less common; only 8% (Table II). In many of these cases, the technique proposed by Gilland using the so called 'Optodynamic Fluid Manometer' has been used (GILLAND 1965). This is an open end, but sensitive, method of manometry that allows reliable measurements even in cases of partial block. In these series, the degree of block increases in the extension of the neck, so that only 15% of the cases showed a normal passage of the fluid. T A B L E 11
Preoperative dynamic manometry 45 cases (8.6 ~) Degree of block Normal Partial block Total block
Position of the neck Neutral Flexion 46 ~ 50 ~ 33 ~ 36 ~ 21% 14%
Extension 15 27 58~
Electromanometry (Table III) has been used on only 16 patients by one of us (LGF). We have followed the technique proposed by Gilland (1962) and found Lakke's book 'The Queckenstedt's test' useful in interpreting the results. The patients in our series of electromanometries occasionally had an advanced clinical picture. This is perhaps the cause of the high proportion of blocks that in extension rcaches the figure of 100%. These patients improved more with operation than average groups did. This is in agreement with the observations of Lakke, who found that patients with an electromanometric block reacted better to operation than those without. T A B L E 111
Preoperative 'electromanometry' 16 cases (3 ~), all grades of myelopathy 4, 5 and 6 Degree of block Position of the neck Neutral Flexion Extension Normal 25 ~ 31 ~ 0 Partial block 44 ~ 50 ~ 19 Total block 31 ~ 19~ 81
27
Preoperative grade of myelopathy: Fig. 8 shows the distribution of the cases by the grade of myelopathy before operation. There are more cases in the intermediate groups but there are quite a few even in the more advanced categories. ),-
-r
CSM
61
158 It,, u-o o
uJ ,,,~r
a:~ OtD
152 127
4 5
70
149
6
NUMBER OF PATIENTS fig. 8
Type o[ operation: The different types of operations have been classified in four groups and six subgroups (Table IV). All groups but one ('large laminectomy') contain a large enough sample for statistical purposes. The anterior approach has been analysed depending on whether the patients were operated at one, two or more than two levels. Laminectomy patients were divided into three groups depending on the size of the laminectomy. T A B L E IV
Type of operation and number of patients Type of operation ~l levels Anterior approach "2 levels f3-4 levels ~small Laminectomy )medium '~ large Laminectomy ÷ ant. approach Laminectomy + post. fixation
Number 121 55 19 95 141 6 42 41
of cases and 23.3 ~ ) 10.5 ~ ~195 3.6 ~/' 18.3~ 27.2~ t242 ! .2 ~ t 8.1% 7.9~
37,5~ 46.6
The group operated by both, anterior and posterior approach in two seances, includes all cases regardless of which type of operation was performed first. The fourth group needs some comments. Patients in this group have been operated with medium sized laminectomy, followed by a posterior fixation, in most instances with the help of a metal plate. The rationale of the procedure and its results, have been published elsewhere (GONZ~LEZ-FER[A 1975). Results of operations: The overall results are shown in figure 9. In the middle of the figure are the unchanged cases, 33°/o. Nearly 60°/o of the patients improved
28 1.7'/. + 4
CSM
I
73% I,-Z
u.I t,O
: ÷
0.9
17.5°/0 ÷
2
÷
1
o
n,, Q.
IMPROVEMENT
AVERAGE
.3
33% 33%
~
59.5%
Z O n~
"
+'lJ
-I
-2
1%
o uJ I.-
6.5%
-3
1%
UJ (3
-4
RESULTS
q2"/.
fig. 9
and 6,51)/0 deteriorated. Mortality has not been represented in this figure, but that were 16 cases, i.e. 3 % of the 521 operated cases. In about half of the cases, death was due to causes related to operation. The average improvement for the whole material is 0.9 grades of the scale. The analysis of the results taking into account the grade of myelopathy before operation and the type of operation is shown in Table V. The ordinate represents ANT.
LAMIN- LAM +
LAM +
APPR ECTOIvftANT.AP FI X.
0.5 33
1.0 27
0.4 19
0.8 22
1o+ , o
O0
0
0.7
1.5
3
2
10 10
, ~ t.kl
o_
4
o w wn,"
5
0
O
