Comparative study of clinical and surgical findings and cortical somatosensory evoked potentials in patients with lumbar spinal stenosis and disc protrusion

Page 1

Acta Neurochir (Wien) (1987) 84:54-63 :Acta Nduro&irurgica �9 by Springer-Verlag 1987

Comparative Study of Clinical and Surgical Findings and Cortical Somatosensory Evoked Potentials in Patients with Lumbar Spinal Stenosis and Disc Protrusion

Ph. Tsitsopoulos l, F. Fotiou 2, D. Papakostopoulos 3, C. Sitzoglou 2, and G. Tavridis t

1 Department of Neurological Surgery, University Thessaloniki, Greece 2 Clinic of Neurology and Psychiatry University Thessaloniki, Greece 3 Burden Institute of Neurology, Bristol, U.K.

Summary

This paper is dealing with a comparative study of clinico-surgical findings and cortical somatosensory evoked potentials (CSEP's) recordings after stimulation of the right and left common peroneal nerve behind the fibula head, in twenty five patients suffering from lumbar spinal stenosis and disc prolapse.

In all instances, the latencies of the first positive wave (the waveform also, when the latency was not discrete) were evaluated. The neurophysiological findings were verified by surgery. In com- bination with other roots, L 3 root was affected in 1 patient, L 4 in 6, L 5 in 13 and S 1 in 11. L 5 was affected alone in 11 and L 5 and S 1 were impaired in combination in 11 patients. Seven patients presented

sural atrophy. The results of the neurophysiological study are described below: There was delayed response on both sides in six patients, while in

ten patients delayed response was found on one (affected) side, inconclusive responses in seven and in two normal. Myelography and CT Scan were performed pre-operatively to ascertain disc protrusion and establish stenosis criteria. The surgical findings were: clear disc protrusion in 4 patients, stenosis in one and combined lesions in 20 (including central disc protrusion in seven).

Sixteen patients out of twenty-five had a follow up neurophysi- ological evaluation in addition to the clinical follow up examination.

In thirteen of the above patients, (taken with the clinical progress) the re-examination gave improved neurophysiological data both as regards latency and P1 waveform. It was obvious that high value latencies were associated with long standing clinical symptoms while at the same time root compression involved more than one level.

Regarding the neurophysiological data and the surgical findings, it was found that in the majority of the cases (92%) these two parameters matched together, so that in such cases a possible prediction of the operative outcome can be given.

Keywords: Disc protrusion; lumbar stenosis; CSEP; laminectomy.

Abbreviations

Neurological findings

L 5 (R): Right fifth lumbar root. L 5 (L): Left fifth lumbar root. L3, L4 (L): Left third and fourth lumbar roots. Ls, S 1 (R): Right fifth lumbar and first sacral roots. Ls, $1 (L): Left fifth lumbar and first sacral roots. L 5, S 1 (R, L): bilateral (right and left) fifth lumbar and first sacral

roots.

Surgical findings

The predominant cause of the lesion, either stenosis (S) or disc protrusion (D) follows the symbol (M) in mixed lesions and the symbols (G +, G + +, G + + +) according to the severity:

S (L 4, L5) R: stenosis at fourth and fifth lumbar intervertebral spaces more on the right.

DR: Disc protrusion to the right. DL: Disc protrusion to the left. DR or DL (Ls, $1): Disc protrusion to the right or to the left

compressing both roots the fifth lumbar and the first sacral. DC: Central disc protrusion. DCR: Central disc protrusion and to the right. DCL: Central disc protrusion and to the left.

In tr o d n e t i o n

B o t h c e n t r a l a n d p e r i p h e r a l s o m a t o s e n s o r y e v o k e d

p o t e n t i a l s ( S E P s ) c a n b e r e c o r d e d b y s u r f a c e a n d

i m p l a n t e d e l ec t rodes , s t i m u l a t i n g p e r i p h e r a l n e r v e s o f

t h e u p p e r a n d l o w e r l i m b s 3, 4, 8, 11, 12, 13

P o s i t i v e w a v e f o r m w i t h 2 6 - 3 4 m s e c l a t e n c y is i n v a r i -

a b l y o b t a i n e d in n o r m a l s u b j e c t s u s i n g s u r f a c e

Page 2

Ph. Tsitsopoulos etaL: Comparative Study of Clinical and Surgical Findings and Cortical Somatosensory Evoked Potentials 55

electrodes placed on the scalp, following common peroneal nerve stimulation behind the head of the fibula.

There is a great number of studies referring to clinical applications of cortical SEPs following medial nerve stimulation mainly in patients with neurological disorders ~, e, 5, 7. On the contrary, reports concerning such applications, following lower limb nerve stimula- tion, started appearing increasingly lately 6, 9, 10, 14, 15

This paper is dealing with the recorded CSEPs, after common peroneal nerve stimulation in patients suffer- ing from lumbar spinal degenerative disease (disc protrusion--spinal canal stenosis), associated with such clinical and neuroradiological pictures indicating surgery.

The aims of this study were: 1. to detect the correlation--if any--between pre-

operative neurophysiological data (CSEPs) with the surgical findings,

2. to compare the post-operative neurophysiological status to the clinical course of the patients, and

3. to determine whether the operative outcome could be foreseen by evaluating the cortical SEPs recorded before the operation.

Clinical Material and Methods

Cortical SEPs were recorded following common peroneal nerve stimulation in twenty five patients (eleven males and fourteen females) aged 28-65 years (1.55-1.76cm height). These patients suffered from lumbar spinal canal stenosis and disc protrusion and subsequently underwent surgery. The control group consisted of sixteen age-matched healthy individuals (1.55-1.80 cm height).

All patients were examined in supine position on a comfortable bed in a quiet room with temperature 22-26 ~ The purpose of the examination was thoroughly explained to the patient. With the consent of the patient we tried to make them feel comfortable with the electrical pulse stimulation. Electrical stimuli were applied through disa type electrodes with the cathode being 3 cm proximal to anode. Stimuli were applied to common peroneal nerve at a site behind fibular head. The intensity of the stimulation was that sufficient, to produce a brisk movement of the ankle joint. The application rate of the electrical stimulus was 1 p/sec with a 0.5 msec duration.

The recording electrode was placed 2cm behind Cz with the reference electrode at Fz (10-20 international system). Cortical instead of lumbar recording was prefered because there was concomi- tant severe lumbar pain and muscle spasm in all our cases at the time of the examination. Monopolic unvarnished stainless steel needles (electrodes) of 0.2 mm diameter were used. Each common peroneal nerve was stimulated separately and the corresponding waves were recorded. Time constant was 0.8 msec and the high frequency filter of 3 .2KH ( - - 3dB). Gain was at 50 gV/1 cm. Although 256 stimuli were sufficient to produce CSEPs but in several patients it was required double number (512) of stimuli.

The parameters which were evaluated included latency and morphology of the first positive wave. The above data were compared

to those of the control group. Criteria used in the evaluation of the abnormal neurophysiological results that were obtained included: The morphology and the latency of the first positive wave of CSEPs, were in this way primarily evaluated.

A latency greater than 2 sd of the control goup, and when the difference of latencies between the most and least affected side was greater than 3 sd were addidtionally evaluated. The clinical picture and the operative findings were compared with the preoperative neurophysiological data and with those one year after surgery (of the twenty-five patients the sixteen were followed up).

In our patients, in addition to plain X-rays, lumbar CT Scan and myelography were carried out, in most of them, to confirm the clinical diagnosis.

During operation, patients were maintained in a prone position on the operative table with the spine flexed at 55-20 ~ Because of the common occurrence of severe combined lesions (disc protrusion- stenosis), the surgical technique used was the same in almost all patients (extensive laminectomy from L 3 to S 1 and exploration of the intervertebral spaces and foramina).

Results

A. Pre-operative Data

1. Neurophysiological Data

a) Control Group (16 cases)

The latency of the first positive wave following the right and left common peroneal nerve stimulation was 30.9 msec with sd 2.2 msec (Fig. 1) and 30.7 msec with sd 1.9 msec respectively.

20ms

Fig. I. CSEP recording in 4 normal subjects (after right common peroneal nerve stimulation). The vertical line shows the average latency of the first positive wave in the normal subjects

Page 3

56 Ph. Tsitsopoulos etal.: Comparative Study of Clinical and Surgical Findings and Cortical Somatosensory Evoked Potentials

The mean difference in latency after right and left stimulation was 0.67 msec and of the sd 0.42msec (Fig. 2).

i 1/Jv + 20ms

Fig. 2. CSEP recorded after separate stimulation of the right and left

common peroneal nerve in the same individual. The similarity of the

latency as well as the morphology of the first positive wave are clearly

shown

S

i Ipv + 2 0 m s

Fig. 3. CSEP in cases 10, 21, 2, 23 (working from above). In the first two cases the latency is 37 and 52 msec respectively, while in the other

two cases the definition of the latency o f the first positive wave appears to be impossible

b) Patients (Table 1) According to the criteria mentioned above, the

following responses were recorded: Normal CSEPs were recorded in 2 patients. Indefinite responses on one side in 2 and on both

sides in 5 patients (Fig. 3). Latency on both sides greater than 2 sd of control

group in 6 patients (Fig. 4). Latency on the affected side in relation to the

healthy one greater than 3 sd of control group in 10 patients (Fig. 5).

A

I/Jv

+ 20ms Fig. 4. Case 16. Severe mixed lesion (disc protrusion to the left-

compressing L 5 root-associated with stenosis at L 5 intervertebral

space). CSEP: Latency, right (A) 37.3 msec, left (B) 36.2msec

'l~ / ..

A ', t ;'-,\,

" f % A r . - , - / ',. "

i O,51Jv

+ 20ms

; \ § 20ms

Fig. 5. Case 17. Severe mixed lesion of slipped discs to the left on L 5

and S 1 roots and stenosis at L3, L 4, L 5 intervertebral spaces. Latency of the first positive wave after right (A) common peroneal nerve is normal 30 msec, while after left (B) common peroneal nerve stimula-

tion the latency was 39 msec

Page 4

Ph. Tsitsopoulos et al.: Comparative Study of Clinical and Surgical Findings and Cortical Somatosensory Evoked Potentials 57

2. Clinical Data (Table 1)

a) Previous Clinical History: All twenty-five patients experienced lumbar and

sciatic pain for a period of two months some going back as long as twenty years (numbness and tingling sensa- tion were also present).

Analysis of past history was as follows: Symptoms for a period of 2 months up to 1 years in 7

patients, symptoms for a period of 1 year up to 10 years in 14

patients, and of 10 years up to 20 years in 4 patients.

b) Data from Detailed Clinical Examination In combination with other roots, L 3 root was

affected in 1 patient, L4in 6, L 5 in 13 and $1 in 11. L 5 was the only root affected in 11 patients. L5 and SI roots were affected in combination in 11 patients while 7 patients showed waisting of sural muscle.

Combined lesions were found in 20 patients while central disc protrusions were located in 7 patients.

Considering the degree of the compression on the neural elements the material was divided into 3 groups clinically.

In the first group (slight compression) there were 2 patients and the type of surgical finding was a clear disc protrusion.

Into the second group (moderate compression) belong 4 patients with combined lesions i.e. disc protrusion and spinal canal stenosis.

(Severe compression) 19 patients were classified into the third group. Two of them were cases of clear disc protrusion, one case with verified stenosis and 16 cases of combined lesions (disc protrusion and stenosis) with obvious narrowing of the canal.

Comparing the neurophysiological and surgical data they were found in agreement in 23 cases (92%) and they did not correspond.

3. Neuroradiological Data

Disc protrusion and/or degeneration was clearly demonstrated on myelography and CT Scan. The stenosis criteria, however, had to be established. Estimation of the degree of lumbar canal stenosis was made by using data from the neuroradiological in- vestigation. It was possible to estimate this parameter from the CT scan pictures and the myelographic appearances. In the transverse sections of the CT scan the calculation of the dimensions of the canal in the lumbar region could be made. While in the myelo- graphic appearances the bilateral narrowing of the contrast column left no doubt as to what extend the stenosis existed. Thus, in our cases the clinical diagnosis was confirmed by these neuroradiological findings. In these cases transaxial CT (high resolution) of the lumbar spine was performed and the anterioposterior (AP) dimension of the canal was electronically measu- red and found to vary from 10 to 15ram. The myelo- graphic appearances of our stenosis cases were of a bilateral multilevel narrowing of the contrast column without visualization of the roots sleeves.

4. Surgical Data (Table 1)

In our material the surgical findings can be classified as follows:

In 4 patients the surgical picture disclosed disc protrusion with no obvious accompanied lesions.

In 1 patient stenosis of the spinal canal was beyond any doubt.

B. Post-operative Estimation

1. Neurophysiological Data (Table 2) Sixteen patients re-examined after a period of one

year thirteen of them presented significant improve- ment regarding the morphology and the latency of the first positive wave (Fig. 6) but the remaining three patients (cases 1, 2, 9) did not present any improvement. Possibly this is due to the long standing compression producing irreversible lesions.

2. Clinical Data (Tables 3, 4)

Examination of the sixteen patients mentioned above after a follow-up period of one year revealed that in cases 1, 2, 9 with no post-operative electrical improvement there were no any significant changes in the clinical picture or in their complaints. Thirteen patients with considerable improvement in the neuro- physiological picture were found to be free from complaints (pain, numbness, tingling sensation) or from signs such as motor power impairment, muscular atrophy. Detailed examination mainly revealed complete absence of tension symptoms and signs with minor or no disturbance of sensation while bet ter walking had been established. In conclusion, 2 out of the 4 reexamined with disc lesions, improved. Eleven out Of the 14 re-examined with combined lesions improved while 3 did not. The remaining 9 patients (i.e. 2 with discs protrusion 1 with pure stenosis and 6 with mixed lesions) have not been reexamined.

Page 5

Tab

le 1

, Neu

roph

ysio

logi

cal (

CSE

P),

Neu

rolo

gica

l and

Sur

gica

l Fin

ding

s

Cas

e Se

x A

ge

Pat

ient

's

Tim

e of

P

reop

erat

ivel

y,

no

year

s he

ight

(cm

) on

set

late

ucy

com

mon

pe

rone

al n

erve

Neu

rolo

gica

l fi

ndin

gs

(ref

erre

d to

roo

ts)

Mus

cle

wai

stin

g S

urgi

cal

find

ings

--re

ferr

ed t

o ro

ots

in d

iscs

ref

erre

d to

int

erve

rteb

ral

spac

es i

n st

enos

is

righ

t le

ft

o �9 r �9

1.

M

49

170

10 y

ears

42

46

2.

M

65

16

5 I4

yea

rs

--

31.2

3.

M

60

16

0 5

mon

ths

30

36.6

4.

F

50

163

2 ye

ars

33.7

33

5.

F

33

165

6 m

onth

s 32

.2

35

6.

M

43

172

10 y

ears

32

.2

38.2

7.

F

47

160

20 y

ears

31

.2

29

8.

F 51

16

6 5

year

s 32

38

9.

M

53

17

0 5

year

s 44

.2

--

10.

F 50

16

4 I0

yea

rs

37

30

11.

F 45

16

5 9

year

s 29

--

12

. M

46

17

5 20

yea

rs

35.6

--

13

. F

48

160

6m

on

ths

37.5

42

.5

14.

F 31

17

0 7

year

s 36

.2

37

15.

F 36

15

9 2

mo

nth

s 33

.1

33.2

i6

. F

40

165

4 ye

ars

37.3

36

.2

17.

M

47

170

10m

onth

s 30

39

18

. M

28

17

2 I

year

35

.5

36.8

19

. M

47

17

6 8

year

s 29

35

.4

20.

M

50

165

4 m

onth

s 31

28

21

. F

50

166

10 y

ears

52

42

22

. F

57

155

15 y

ears

35

23

. F

41

157

5 ye

ars

--

--

24.

F 52

15

6 2

year

s 29

30

.8

25.

M

57

167

4 ye

ars

42

--

Ls,

S 1

(L)

L5,

S 1

(R,L

) L5

(L)

L5 (a

) Ls

(L)

L 5

(L

) L

5 (

R)

La,

L 5

, S 1

(L)

L5,

S 1

(L)

Ls,

S 1

(R)

L4,

Ls,

S 1

(R)

L4,

Ls,

S I

(R,

L)

L5 (R

) L

5, S

1 (R

) L

5 (

L)

L s

(L)

Ls,

S

1 (L

) L

s, S

t (L

) L

4, L

5 (L

) L

5 (

L)

L 3,

L 4

(L)

L4,

L 5

(R

, L

) L5

(R)

L s

(R)

Ls,

S 1

(L)

L.

sura

lis

R.

sura

lis

L.

sura

lis

L.

sura

lis

R.

sura

lis

L.

sura

lis

L.

sura

lis

M (

G +

+ +

), S

(L

4, L

5),

DC

L (

SI)

M (

G +

+ +

), D

C (

Sl)

, S

(L4,

L5)

M

(6

+ +

+),

S (

L 4,

Ls)

, D

L (

Ls)

M

(G

+ +

+),

S (

L 4,

Ls)

, D

R (

L5)

(G

+ +

+),

DL

(L

s)

M (

G +

+),

DL

(L

5),

S (L

4, L

s)

M (

G +

+),

S (

L4,

Ls)

, D

C (

L4)

, D

R (

Ls)

M

(G +

+ +

), S

(L

4, L

5) ,

DC

(L

4) ,

DL

(St

) M

(G

+ +

+ )

, D

L (

Ls)

, S

(L4,

Ls)

M

(G

+ +

+),

De

(SI)

, S

(L 4,

Ls)

R

M (

a +

+ +

), D

R (

St),

DC

(L

s),

S (L

3, L

4)

M (

G +

+ +

), D

R (

Ls)

, S

(Ls)

, D

C (

$1)

M (

G +

+),

DR

(L

s),

DR

(S1

) , S

(L

4, L

s)

(G +

+ +

), D

CR

(L

s, S

~)

M (

G +

+ +

), D

L (

Ls)

, S

(L5)

M

(G

+ +

+),

DL

(L

s),

S (L

s)

M(G

+ +

+),

DL

(L

s),

S (L

3, L

4, L

5),

DL

(S1

)

M (

G +

+ +

), D

L (

L5)

, D

L (

Sj),

S (

L 4,

Ls)

M

(a

+ +

), S

(L

4, L

s),

DL

(L

s)

(G +

), D

L (

Ls)

M

(G

+ 4

- +

), S

(L

3, L

4, L

5),

DL

(L

a),

DR

(S1

) (G

+ +

+),

S (

L 3,

L 4,

Ls)

M

(G

+ +

+),

DR

(L

s),

S (L

4, L

5)

(a +

), D

R (

Ls)

M

(G

+ +

+),

S (

L 4,

Ls)

, D

L (

Sl)

<< ('3

f~

ra,]

m C~

�9

o �9

Page 6

Ph. Tsitsopoulos et al.: Comparative Study of Clinical and Surgical Findings and Cortical Somatosensory Evoked Potentials

Table 2. Neurophysiological Findings (CSEP)

59

Case no. Patient 's height (cm) Preoperatively, latency common peroneal nerve

1 year postoperatively,

latency common peroneal nerve

right left right left

!. 170 42 46 41.5 43.4

2. 165 - - 31.2 - - 32

3. 160 30 36.6 32 32.1

4. 163 33.7 33 31.4 30.9

5. I65 32.2 35 32.4 33

6. I72 32.2 38.2 33.1 33.4

7. 160 31.2 29 31.2 30

8. 166 32 38 32 33.1

9. 170 44.2 - - 38.9 - - i0. 164 37 30 36 35

11. 165 29 32 36.2

12. 175 35.6 - - 36.2 38.2

13. 160 37.5 42.5 36.5 39

I4. 170 36.2 37 32 31

i5. 159 33.I 33.2 30 31

16. i65 37.3 36.2 3i 32

A

B

i lbzv + 20ms

Fig. 6. Case 6. The latency of the first positive wave for the left

common peroneal nerve was 38.2msec pre-operatively (A) and

33.4 msec post-operatively (B) one year later. Difference is not only seen in the latency but in the wave morphology as well

Discussion

Normal values of the latency of P1 in adults vary between 26 and 34 sec, as previous authors have also stated 12, 16, 17. Our results refer to these values.

These most valuable parameter used in the evalua- tion of the cortical SEPs is the latency of the first positive wave. Due to its variance, the waveforms (amplitude-duration) can not be used according to our experience and that of others 6 in the determination of

cortical SEPs changes. For this reason, in our study, we mainly evaluated the latency of the waveform while additional information was obtained in cases of charac- teristic changes of the waveform.

Stejkal in 1980 evaluated somatosensory evoked potentials in compressing syndromes of the cervical posterior roots. The percentage of the first positive wave latency and alteration in the waveform comparing our surgical and neurophysiological findings is 92%. The discrepancy recorded in the two cases with no neurophysiological deficit despite severe and signifi- cant surgical findings might be attributed to a large canal and foraminal dimensions resulting in no great neurological damage solar. That is why a less severe clinical picture was associated with normal neurophysi- otogical data despite the pronounced surgical lesions.

The duration and degree of root compression are responsible for the pathogenesis of degeneration which caused the increased latency and the waveform alterations.

The degree of compression and the extension of the level of its application (to more than one level) were important factors in the appearance of the latency. Thus, it was obvious that latencies of greater value appeared in combination with clinical symptoms of long duration, while root compression involved more than one level.

Page 7

Tab

le 3

. C

ombi

ned

Lesi

ons

(Ste

nosi

s an

d D

iscs

)

Cas

e Pr

eope

rati

ve a

sses

smen

t

no.

Cli

nica

l fi

ndin

gs

l0

11

12

i3

15

16

i7

Neu

rolo

gica

l N

euro

phys

iolo

gica

l fi

ndin

gs

find

ings

righ

t le

ft

Surg

ical

con

firm

atio

n,

refe

r, t

o ro

ots

in d

isks

Post

oper

ativ

e as

sess

men

t

num

bnes

s, t

ingl

ing,

mot

or p

ower

inv

olv.

di

min

ishe

d se

nsat

ion,

mus

cle

wai

stin

g nu

mbn

ess

ting

ling

, m

otor

pow

er i

nvol

v.

dim

inis

hed

sens

atio

n, m

uscl

e w

aist

ing.

pa

in,

num

bnes

s, m

otor

pow

er i

nvol

v.

tens

ion

sign

s pa

in,

num

bnes

s, m

otor

pow

er i

nvol

v.

tens

ion

sign

s nu

mbn

ess

pain

, m

otor

pow

er i

nvol

v.

dim

inis

hed

sens

atio

n

pain

, nu

mbn

ess

ting

ling

, m

otor

pow

er i

nvol

v.

tens

ion

sign

s pa

in,

num

bnes

s, t

ingl

ing,

mot

or p

ower

inv

olv.

m

uscl

e w

aist

ing

(roo

ts)

L 5,

S I

(L)

42

46

L.

sura

lis

L 5,

S l

(RL

) --

31

.2

R.

sura

lis

L 5

(L)

30

36.6

L s

(R)

33.7

33

L 5

(L)

32.2

38

.2

refe

r, t

o in

terv

erte

br,

spac

es

in s

teno

sis

M(G

++

+)

S (L

4, L

s),

DC

L (

81)

M(G

++

+)

DC

(S

l) ,

S (L

4, L

S)

M(G

++

+)

S(L

4, L

s),

DL

(L

s)

M(G

++

+)

S (L

4,

Ls)

, D

R (

Ls)

M

(6+

+)

DL

(L

s),

S (L

4, L

5)

Neu

roph

ysio

logi

cal

Cli

nica

l ex

amin

atio

n fi

ndin

gs

pain

, nu

mbn

ess,

tin

glin

g, m

otor

pow

er i

nvol

v.

dim

inis

hed

sens

atio

n te

nsio

n si

gns,

mus

cle

wai

stin

g pa

in,

num

bnes

s ti

ngti

ng m

otor

pow

er i

nvol

v.

tens

ion

sign

s, d

imin

ishe

d se

nsat

ion

pain

, nu

mbn

ess

mot

or p

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olv.

di

min

ishe

d se

nsat

ion

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, nu

mbn

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tin

glin

g m

otor

pow

er i

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v.

tens

ion

sign

s, m

uscl

e w

aist

ing

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num

bnes

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ing,

mot

or p

ower

inv

olv.

di

min

ishe

d se

nsat

ion

pain

tin

glin

g, n

umbn

ess,

ten

sion

sig

ns

pain

, ti

ngli

ng,

num

bnes

s, t

ensi

on s

igns

pain

, ti

ngli

ng,

num

bnes

s, m

otor

pow

er

invo

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ent,

dim

inis

hed

sens

atio

n

L 5

(R)

31.2

29

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(L)

32

38

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sura

lis

M(G

++

) S

(L 4,

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(L4

) D

R (

Ls)

M

(G+

++

) S

(L4,

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, D

C (

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(Sl

)

M(G

++

+)

Ls,

S

1 (L

) 44

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--

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nral

is

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(R)

37

30

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(R)

29

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L

s, S

l (R

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--

R

. su

rali

s

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(L)

37.5

42

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L 5

(L)

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33

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(L)

37.3

36

.2

DL

(L

s),

S (L

4, L

5)

M(G

++

+)

DC

(S1

), S

(L4,

Ls)

R

M(G

++

+)

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(SI

), D

C (

L5,

S (L

3, L

4)

M(G

++

+)

DR

(L

s),

S (L

s) ,

DC

($1

) M

(G

++

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R (

Ls)

, D

R (

$1),

S

(L 4,

L5)

M

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Ls)

, S

(Ls)

righ

t le

ft

L5,

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(L)

30

39

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lis

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++

+)

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3, L

4, L

5)

DL

($1

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41.5

43

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no i

mpr

ovem

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mus

cle

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32

no

im

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emen

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uscl

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aist

ing

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30

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prov

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inor

sen

sati

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dist

urba

nce

mus

cle

wai

stin

g 38

.9

--

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mpr

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mus

cle

wai

stin

g 36

35

im

prov

emen

t

32

36.2

im

prov

emen

t

36.2

38

.2

impr

ovem

ent

mus

cle

wai

sfin

g

36.5

39

im

prov

emen

t m

inor

sen

sati

on

dist

urba

nce

30

31

impr

ovem

ent

31

32

impr

ovem

ent

not

re-e

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Page 8

18

t9

21

23

25

pain

, ti

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er i

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v.

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ion

sign

s pa

in,

num

bnes

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ing,

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or p

ower

inv

olv.

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, nu

mbn

ess,

ten

sion

sig

ns,

dim

inis

hed

sens

atio

n, m

otor

pow

er i

nvol

vem

ent

pain

, ti

ngli

ng,

num

bnes

s, t

ensi

on s

igns

, m

otor

po

wer

inv

olve

men

t, d

imin

ishe

d se

nsat

ion

pain

, ti

ngli

ng,

num

bnes

s, s

ensa

tion

dim

inis

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m

otor

pow

er i

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vem

ent

mus

cle

wai

stin

g

L5,

S I

(L)

35.5

36

.8

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(L

) 29

35

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L 4

(R,

L)

52

42

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R)

L 5

, S

1 (L

) 42

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. su

rali

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++

+)

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(L

s),

DL

(Sj

), S

(L

4, L

s)

M(G

++

)

S (L

4, L

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(L

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M(G

++

+)

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3, L

4, L

s),

DE

(L

4) ,

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($1

) M

(G+

++

)

DR

(L

5),

S (L

4, L

s)

M(G

++

+)

S (L

4, L

s),

DL

(S1

)

not

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xam

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no

t re

-exa

min

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not

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ined

not

re-e

xam

ined

not

re-e

xam

ined

not

re-e

xam

ined

not

re-e

xam

ined

no

t re

-exa

min

ed

not

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not

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not

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c~

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c~

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Tab

le 4

. P

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psed

Dis

cs

o

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e P

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ive

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ssm

ent

rl O

.

Cli

nica

l fi

ndin

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tope

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sses

smen

t

Neu

rolo

gica

l N

euro

phys

iolo

gica

l S

urgi

cal

Neu

roph

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find

ings

fi

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conf

irna

atio

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amin

atio

n (r

ef.

to r

oots

) re

f. t

o ro

ots

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t le

ft

righ

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Cli

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('3

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ting

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ion,

ten

sion

sig

ns

14

pain

num

bnes

s, m

otor

pow

er i

nvol

vem

ent,

di

min

ishe

d se

nsat

ion,

ten

sion

sig

ns

20

pain

, nu

mbn

ess,

mot

or p

ower

inv

olve

men

t,

dim

inis

hed

sens

atio

n, t

ensi

on s

igns

24

pa

in n

umbn

ess,

mot

or p

ower

inv

olve

men

t,

dim

inis

hed

sens

atio

n, t

ensi

on s

igns

L 5

(L)

32.2

35

G

+ +

+

32.4

33

im

prov

emen

t D

L (

Ls)

lo

w

back

pa

in

stil

l le

ft

L 5,

S 1

(R)

36.2

37

G

+ +

+

32

3t

impr

ovem

ent

DC

R (

L5,

Si)

L

5 (

L)

31

28

G +

no

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-exa

min

ed

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(L

s)

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(R

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30

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G+

no

t re

exam

ined

D

R (

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Sten

osis

(pu

re)

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e P

reop

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ive

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ssm

ent

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tope

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ve a

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smen

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o

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. ro

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+ +

+

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min

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igns

S

(L3,

L4,

Ls)

Page 9

62 Ph. Tsitsopoulos et al.: Comparative Study of Clinical and Surgical Findings and Cortical Somatosensory Evoked Potentials

Latency of the Pl (first positive wave) was observed

in all cases o f m o t o r and sensory disturbances, while

muscle waisting correlated with a first positive wave

latency of greater value.

In cases where we were unable to record CSEPs,

severe degenerative lesions (osteophytes, thickened

l igamentum flavum and narrowing of the lumbar spinal

canal and foramina, or prot rus ion o f a large disc) were

present. Dur ing operation, severe compression of the

roots was f o u n d , which displaced and strangulated

before entering the foramina and were also adherent to

the pro t ruding disc.

An irreversible lesion (root damage) seemed possible

in a patient (case 9) who failed to give a response during

an a t tempt o f CSEP recording twelve months following surgery. Indeed, during the opera t ion a roo t lesion was

confirmed. A m o n g the eight (8) patients with central

disc protrusion, an increase in latency was recorded

bilaterally in one patient, latency on one side was found

in three patients, while an indefinite response was

obtained in another patient and latency on one side in

the last three. The above findings confi rm that central

disc protrusions have serious neurophysiological con-

sequences. More than that, in cases o f central disc

protrusion, the greater latency was recorded on the side

with the mos t severe roo t compression. Non- record ing

or recording of great latencies o f CSEPs contralateral ly

to the affected side, in four patients (cases 1, 11, 23, 25)

were mos t likely due to a combina t ion o f lesions (disc

w o t r u s i o n and stenosis) and displacement o f neural

structures (sleeve and roots). I t seems possible to us,

that the slight changes o f CSEPs recorded in two

patients, and regarded as normal according to general

criteria, cited previously, might have been regarded as

abnormal not only due to the large canal and foraminal

dimensions, as already discussed, but, additionally,

because these patients were shorter in stature than other

patients.

A definite improvement o f the latency was noticed

post-operat ively in all but three patients ment ioned

above. In one o f them the cause was a severe destructive lesion o f the root. In the rest o f the patients who showed

no improvement o f the neurophysiological picture, age (over 50) must be held responsible for this, as well as the long dura t ion o f symptoms (5-14 years) and the

presence o f muscle waisting.

Therefore, a possible prognosis regarding the out- come can be made in certain patients where neurophysi- ological informat ion is in agreement with clinical and

surgical data.

References

I. Anziska B, Cracco RQ, Cook AW, Feld EW (1978) Somato- sensory far-field potentials: studies in normal subjects and patients with multiple sclerosis. Electroencephalogr Clin Neu- rophysiol 45: 602-610.

2. Anziska B, Cracco RQ (1980) Short latency somatosensory evoked potentials: studies in patients with focal neurological disease. Electroencephalogr Clin Neurophysiol 49: 227-239.

3. Cracco RQ (1973) Spinal evoked responses: peripheral nerve stimulation in man. Electroencephalogr Clin Neurophysiol 35: 379-386.

4. Desmedt JE, Cheron G (1986a) Central somatosensory con- duction in man: neural generators and interpeak latencies of the far-field components recorded from neck and right or left scalp and earlobes. Electroencephalogr Clin Neurophysiol 50: 382- 403.

5. Dorfman LJ, Bosley TM, Cummins KL (1978) Electrophysiolog- ical localization of central somatosensory lesions in patients with multiple sclerosis. Electroencephalogr Clin Neurophysiol 44: 742-753.

6. Dorfman LJ, Perkash I, Bosley TM, Cummins K (1980) Use of cerebral evoked potentials to evaluate spinal somatosensory function in patients with traumatic and surgical myelopathies. J Neurosurg 52: 654-660.

7. Green JB, McLeod S (1979) Short latency somatosensory evoked potentials in patients with neurological lesions. Arch Neurol (Chic) 36: 846-851.

8. Jones SJ, Small DG (1978) Spinal and subcortical evoked potentials following stimulation of the posterior tibial nerve in man. Electroencephalogr Clin Neurophysiol 44: 299-306.

9. Macon JB, Poletti CE, Sweet WH, Ojemann RG, Zervas NT (1982) Conducted somatosensory evoked potentials during spinal surgery. Part2: Clinical applications. J Neurosurg 57: 354-359.

10. Mizrahi EM, Crawford ES (1984) Somatosensory evoked po- tentials during reversible spinal cord ischemia in man. Electroen- cephalogr Clin Nenrophysiol 58: 120-126.

11. Papakostopoulos D, Crow H (1980) Direct Recording of the Somatosensory Evoked Potentials from the Cerebral Cortex of Man and the Difference between Precentral and Postcentral Potentials. In: Desmedt JE (ed) Clinical uses of cerebral, brainstem and spinal somatosensory evoked potentials. Prog Clin Neurophysiol vol 7. Karger, Basel pp 15-26.

12. Rossini P, Cracco RQ, Cracco JB, House W (1981) Short latency somatosensory evoked potentials to peroneal nerve stimulation, scalp topography and the effect of different frequency filters. Electroencephalogr Clin Neurophysiol 52: 540-552.

13. Schramm J, Hashizume K, Fukushima T, Takahashi H (1979) Experimental spinal cord injury produced by slow, graded compression. Alterations of cortical and spinal evoked poten- tials. J Neurosurg 50: 48-57.

I4. Stejskal L (1980) Somatosensory evoked potentials in posterior root compression syndrome. Electoencephalogr Clin Neurophy- siol 48:56 p.

15. Tsitsopoulos Ph, Photiou Ph, Papakostopoul0s D, Athanasiadis D, Sitjoglou C, Tavridis G (1983) Cortical somatosensory evoked potential in patients with lumbar spinal stenosis and disc

Page 10

Ph. Tsitsopoulos et al.: Comparative Study of Clinical and Surgical Findings and Cortical Somatosensory Evoked Potentials 63

protrusion. Proceedings ofX Panhellenic Congress of Neurology and Psychiatry, Vol II, pp 214-230, Thessaloniki.

16. Tsumoto T, Hirose N, Nonaka S, Takahashi M, (1972) Analysis of somatosensory evoked potentials to lateral popliteal nerve stimulation in man. Electroencephalogr Clin Neurophysiol 33: 379-388.

17. Vas GA, Cracco JB, Cracco RQ (1981) Scalp recorded short latency cortical and subcortical somatosensory evoked poten-

tials to peroneal nerve stimulation. Electroencephalogr Clin Neurophysiol 52: 1-8.

Authors' address: Dr. Ph. Tsitsopoulos, Department of Neuro- logical Surgery, Aristotelian University Thessaloniki Medical School, Thessaloniki, Greece. Dr. F. Fotiou, Clinic of Neurology and Psychiatry, Axepa Hospital Thessaloniki, Greece.