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O101 Stenosis of the lumbar spinal canal — Neuropathy of axonal type : Electrophysiological differential diagnosis
Communications orales/Oral communications
0100
099 NEUROPHYSIOLOGICAL ASSESSMIKNT OF CERVICAL SPONDY!IYfIC MYELOPATHY. D. Restuccia, V. Di Lazzaro, NF. Lo Monaco, A. Evoli and p. Tonal±, Catholic lhiversity, Rome (ITALY).
CORTICALSOMATOSENSORY POTENTIALS EVOKED BY AIRPUFF STIMULATION OF THE LUMBOSACRAL DERMATOMES: NORMAL VALUES AND RESULTS OF 15 PATIENTS WITH RADICULOPATHIES
Our purpose was to enhance the functional assessment in cervical spondylosis, by a multimodality exploration of cervical spinal cord structures. We studied 7 patients with cervical spondylotic myelopathy established by clinical signs and confirmed by Magnetic Resonance Imaging (MR_I). Somatosensory Evoked Potentials (SEPs) were recorded after stimulation of median, radial and ulnar nerves obtaining informations on dor sal colurmn-lemniscal pathway conduction and postsynaptic act± vity in the central grey matter at different levels of the cervical cord. Magnetic stimulation of the motor cortex and cervical spine provided evaluation of the antere-lateral seg ments of the cervical spinal cord. SEPs were performed on 36 upper limb nerves (14 median, i0 radial, 12 ulnar n.). A disappearance of NI3 were following stimulation of one or mere of the tested nerves suggested the segmental involvement of the central grey matter in 6 out of 7 patients. Ibis finding was more commonly observed after radial n. stimulation (6 out of iO SEPs) and showed a strong correlation with clinical and radiological signs of high cervical spinal cord compression. The absence or the latency delay of the PI4 wave was observed in 2 out 7 patients (4 ulnar, 2 median, 2 radial n.) who also showed clear-cut clinical evidence of impairment of joint and touch sensations of upper limbs. Magnetic stimulation of motor cortex and cervical spine revealed alteration of the central motor pathways predominantly in the myotomes caudal to the site of compression doct;nented by M.R.I.. In conclusion, abnormality of N13 wave seems to be a reliable sign of segmental damage of the cervical cord, whereas abnormalities of PI4 wave and of motor responses to magnetic stimulation m y disclose respectively either the involvement of dorsal columns or of the antere-lateral pathways.
O101 STENOSIS
OF TT~E L U M B A R
OF A X O N A L
TYPE
SPINAL
CANAL
- NEUROPATHY
: ELECTROPHYSIOLOGICAL
DIFFERENTIAL
DIAGNOSIS H. M o l i t o r , Wfirzburg
W.
(W.
Hetzel,
Neurol.
In e l e C t r o p h y s i o l o g i c a l
practice
of a x o n a l
myographic
abnormalities
ral n e u r o g e n l c potential tion
velocity. causes
above
mentionned
Based
on the
L5,
meters
of l u m b a r
of
a periphe-
of c o m p o u n d
decrease
single
NCV
of m e r v e spinal
muscle conduc-
canal
in the
cases
spinal
with
value
the
stenosis
and
significant
two
conditions.
following
discussed.
of
F-wave-
most
of S E P
is b r i e f l y
nerve
stimulation
CT-proven
Tibial-SEP
the
data
analysis,
and peroneal
SEP fol~wing
canal
to be
potential
of t i b i a l
to d i s t i n g u i s h
stimulation
of the
base
of e l e c t r o p h y s i o l o g i c a l
Segmental-
The d i a g n o s t i c
on the
abnormalities
activity,
proved
diagnosis
is m a d e
tests.
analysis
L4)ih 29
the l u m b a r latency
marked
identical
pattern,
Tibial-SEP,
Juliusspital
demonstrating
Stenosis
often
activity
type
lesion,reductlon
without
(spontaneous
Dept.
Germany)
neuropathy
$I,
35s
para-
segmental
of
R.J. Schimsheimer , Th. Stijnen, J.v.d. Sluijs.Dept. of CI. Neurophysialogy and Medical Statistics, Ac.Hospital Dijkzigt, Rotterdam, The Netherlands Cortical potentials were elicited by airpuff stimulation of the L 5 and SI dermatome in a group of healthy volunteers and in 15 patients with lumbosacral radiculopathies. The results were compared with the SEP's obtained by conventional electrical stimulation. Both stimulus modal±ties produce stable and good reproducible cortical responses of similar waveform. The most stable second negative peak, labeled N2, was used in this study. Mean latencies (in msec) were: N2 L5 air = 61.1 ± 3.3, N2 L5 electr. = 55.7 i 3.7 N2 SI air = 61.2 ± 3.9, and N2 S1 electr. = 55.1 ± 2.9 The maximum R/I difference (mean + 3 SD) was 5.7 msec, 5.9 msec, 7.2 msec and 7.2 msec for respectively N2 L5 air, N2 L5 electrical, N2 S1 air and N2 S1 electrical. Single regression analysis showed a significant influence of height, but not age upon all latencies. Multiple regression analysis showed a significant influence of height and age together upon the latencies of the electrical SEP, but not upon the airpuff SEP. Gender had no effect on the cortical components. No significant difference was found between the latencies on the two sides. Airpuff SEP's may provide a good slternative for electrical stimulation. The results of the patients will be discussed.
0102 NON I N V A S I V E E L E C T R I C A L AND MAGNETIC S T I M U L A T I O N OF LUMBOSACRAL ROOTS I N MAN: METHODOLOGICAL CONSIDERATIONS W. Troni ,M. Coletti M o i a , R. Cavallo and L. Bergamini 1st Neurological Clinic, University of Turin, Turin (Italy) The r e c e n t t e c h n i q u e s for non-invasive electrical and m a g n e t i c stimulation of neural structures in man a l s o offer the opportunity to directly test the less accessible segments of the P.N.S. (plexuses and roots), up t o d a y incompletely stud i e d by means o f i n d i r e o t s m e t h o d s , s u c h as t h e H and F responses. Stimulation at the lumbosaoral level presents complex methodological p r o b l e m s due to obvious anatomical reasons. Several uncertainties persist a s i t c o n c e r n s 1) t h e n e u r a l structures preferentially activated, 2) the actual site of activation, 3) the feasibility of a supramaximal stimulation of the ventral roots, 4) the best location of the stimulating electrodes. I n 12 n o r m a l v o l u n t e e r s , r a n g i n g i n age b e t w e e n 21 and 6 5 y s , e l e c t r i c a l and m a g n e t i c s t i m u l a t i o n was performed at different levels of the lumbosacPal and l o w t h o r a c i c spinal c o l u m n . The m o t o r r e s p o n ses evoked by s u c h stimulation were bilaterally and s i m m e t r i c a l l y recorded from various muscles of the lower legs. The main goal o f t h e s t u d y was t o compare the effectiveness of electrical and m a g n e tic stimuli as w e l l a s that of different montages of the stimulating electrodes. We t r i e d to precise the site of activation m a i n l y by evaluating the latencies of H and M responses elicited at the different levels of stimulation. Our results indicate that a supPamaximsl activation of the ventral roots at the origin from the conus medullaris can steadily be o b t a i n e d o n l y by means o f t h e e l e c t r i cal stimuli and by u t l i z i n g a doric-ventral arrangement of the stimulating electrodes.
0100
099 NEUROPHYSIOLOGICAL ASSESSMIKNT OF CERVICAL SPONDY!IYfIC MYELOPATHY. D. Restuccia, V. Di Lazzaro, NF. Lo Monaco, A. Evoli and p. Tonal±, Catholic lhiversity, Rome (ITALY).
CORTICALSOMATOSENSORY POTENTIALS EVOKED BY AIRPUFF STIMULATION OF THE LUMBOSACRAL DERMATOMES: NORMAL VALUES AND RESULTS OF 15 PATIENTS WITH RADICULOPATHIES
Our purpose was to enhance the functional assessment in cervical spondylosis, by a multimodality exploration of cervical spinal cord structures. We studied 7 patients with cervical spondylotic myelopathy established by clinical signs and confirmed by Magnetic Resonance Imaging (MR_I). Somatosensory Evoked Potentials (SEPs) were recorded after stimulation of median, radial and ulnar nerves obtaining informations on dor sal colurmn-lemniscal pathway conduction and postsynaptic act± vity in the central grey matter at different levels of the cervical cord. Magnetic stimulation of the motor cortex and cervical spine provided evaluation of the antere-lateral seg ments of the cervical spinal cord. SEPs were performed on 36 upper limb nerves (14 median, i0 radial, 12 ulnar n.). A disappearance of NI3 were following stimulation of one or mere of the tested nerves suggested the segmental involvement of the central grey matter in 6 out of 7 patients. Ibis finding was more commonly observed after radial n. stimulation (6 out of iO SEPs) and showed a strong correlation with clinical and radiological signs of high cervical spinal cord compression. The absence or the latency delay of the PI4 wave was observed in 2 out 7 patients (4 ulnar, 2 median, 2 radial n.) who also showed clear-cut clinical evidence of impairment of joint and touch sensations of upper limbs. Magnetic stimulation of motor cortex and cervical spine revealed alteration of the central motor pathways predominantly in the myotomes caudal to the site of compression doct;nented by M.R.I.. In conclusion, abnormality of N13 wave seems to be a reliable sign of segmental damage of the cervical cord, whereas abnormalities of PI4 wave and of motor responses to magnetic stimulation m y disclose respectively either the involvement of dorsal columns or of the antere-lateral pathways.
O101 STENOSIS
OF TT~E L U M B A R
OF A X O N A L
TYPE
SPINAL
CANAL
- NEUROPATHY
: ELECTROPHYSIOLOGICAL
DIFFERENTIAL
DIAGNOSIS H. M o l i t o r , Wfirzburg
W.
(W.
Hetzel,
Neurol.
In e l e C t r o p h y s i o l o g i c a l
practice
of a x o n a l
myographic
abnormalities
ral n e u r o g e n l c potential tion
velocity. causes
above
mentionned
Based
on the
L5,
meters
of l u m b a r
of
a periphe-
of c o m p o u n d
decrease
single
NCV
of m e r v e spinal
muscle conduc-
canal
in the
cases
spinal
with
value
the
stenosis
and
significant
two
conditions.
following
discussed.
of
F-wave-
most
of S E P
is b r i e f l y
nerve
stimulation
CT-proven
Tibial-SEP
the
data
analysis,
and peroneal
SEP fol~wing
canal
to be
potential
of t i b i a l
to d i s t i n g u i s h
stimulation
of the
base
of e l e c t r o p h y s i o l o g i c a l
Segmental-
The d i a g n o s t i c
on the
abnormalities
activity,
proved
diagnosis
is m a d e
tests.
analysis
L4)ih 29
the l u m b a r latency
marked
identical
pattern,
Tibial-SEP,
Juliusspital
demonstrating
Stenosis
often
activity
type
lesion,reductlon
without
(spontaneous
Dept.
Germany)
neuropathy
$I,
35s
para-
segmental
of
R.J. Schimsheimer , Th. Stijnen, J.v.d. Sluijs.Dept. of CI. Neurophysialogy and Medical Statistics, Ac.Hospital Dijkzigt, Rotterdam, The Netherlands Cortical potentials were elicited by airpuff stimulation of the L 5 and SI dermatome in a group of healthy volunteers and in 15 patients with lumbosacral radiculopathies. The results were compared with the SEP's obtained by conventional electrical stimulation. Both stimulus modal±ties produce stable and good reproducible cortical responses of similar waveform. The most stable second negative peak, labeled N2, was used in this study. Mean latencies (in msec) were: N2 L5 air = 61.1 ± 3.3, N2 L5 electr. = 55.7 i 3.7 N2 SI air = 61.2 ± 3.9, and N2 S1 electr. = 55.1 ± 2.9 The maximum R/I difference (mean + 3 SD) was 5.7 msec, 5.9 msec, 7.2 msec and 7.2 msec for respectively N2 L5 air, N2 L5 electrical, N2 S1 air and N2 S1 electrical. Single regression analysis showed a significant influence of height, but not age upon all latencies. Multiple regression analysis showed a significant influence of height and age together upon the latencies of the electrical SEP, but not upon the airpuff SEP. Gender had no effect on the cortical components. No significant difference was found between the latencies on the two sides. Airpuff SEP's may provide a good slternative for electrical stimulation. The results of the patients will be discussed.
0102 NON I N V A S I V E E L E C T R I C A L AND MAGNETIC S T I M U L A T I O N OF LUMBOSACRAL ROOTS I N MAN: METHODOLOGICAL CONSIDERATIONS W. Troni ,M. Coletti M o i a , R. Cavallo and L. Bergamini 1st Neurological Clinic, University of Turin, Turin (Italy) The r e c e n t t e c h n i q u e s for non-invasive electrical and m a g n e t i c stimulation of neural structures in man a l s o offer the opportunity to directly test the less accessible segments of the P.N.S. (plexuses and roots), up t o d a y incompletely stud i e d by means o f i n d i r e o t s m e t h o d s , s u c h as t h e H and F responses. Stimulation at the lumbosaoral level presents complex methodological p r o b l e m s due to obvious anatomical reasons. Several uncertainties persist a s i t c o n c e r n s 1) t h e n e u r a l structures preferentially activated, 2) the actual site of activation, 3) the feasibility of a supramaximal stimulation of the ventral roots, 4) the best location of the stimulating electrodes. I n 12 n o r m a l v o l u n t e e r s , r a n g i n g i n age b e t w e e n 21 and 6 5 y s , e l e c t r i c a l and m a g n e t i c s t i m u l a t i o n was performed at different levels of the lumbosacPal and l o w t h o r a c i c spinal c o l u m n . The m o t o r r e s p o n ses evoked by s u c h stimulation were bilaterally and s i m m e t r i c a l l y recorded from various muscles of the lower legs. The main goal o f t h e s t u d y was t o compare the effectiveness of electrical and m a g n e tic stimuli as w e l l a s that of different montages of the stimulating electrodes. We t r i e d to precise the site of activation m a i n l y by evaluating the latencies of H and M responses elicited at the different levels of stimulation. Our results indicate that a supPamaximsl activation of the ventral roots at the origin from the conus medullaris can steadily be o b t a i n e d o n l y by means o f t h e e l e c t r i cal stimuli and by u t l i z i n g a doric-ventral arrangement of the stimulating electrodes.