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Aspects of the normal and abnormal motor units obtained by using different EMG methods
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F298 AUTONOMICDYSFUNCTION IN UREMIA SOLDERS, G. and PERSSON, A.~Dept. of C l i n . Neurophysiology, Huddinge, Univ. Hospital, Sweden Symptoms of autonomic f a i l u r e are common among patients with renal f a i l u r e . In order to establish r e l i a b l e methods to study these complications, we have studied the R-R v a r i a t i o n s in patients on regular haemodialysis. METHODS: The R-R v a r i a t i o n s in the ECG were recorded as consecutive R-R i n t e r v a l s and the v a r i a t i o n s r e l a t i v e to mean R-R i n t e r v a l were calculated for one minute periods during normal breathing (N%) and during deep breathing (D%) as described e a r l i e r (Acta Neurol. Scand~. The N% and D% values were compared to age-matched controls. Furthermore MCV and SCV in the median, peroneal and sural nerves and the v i b r a t i o n thresholds d i s t a l sites were recorded with conventional technique. RESULT: Patients with chronic renal f a i l u r e showed greatly impaired R-R v a r i ations. Most patients had also signs of d i f f u s e neuropathy. The preliminary r e s u l t s indicate that there was a covariation between autonomic and peripheral neuropathy. DISCUSSION: The R-R v a r i a t i o n s are believed to depend on an i n t a c t vagal r e f l e x arc. E a r l i e r we have shown t h i s test to be a simple and r e l i a b l e test on autonomic dysfunction provided that age-matched controls are used. The present study shows that autonomic f a i l u r e is a common f i n d i n g in patients on haemodialysis due to renal f a i l u r e . We believe t h i s test to be of great value in the c l i n i c a l evaluation of uremic patients and in the preoperative i n v e s t i gation before k i d n e y - t r a n s p l a n t a t i o n . Involvement of cardiac nerves probably raise the r i s k of cardio-vascular complications during surgery.
F299 MYOTONICDYSTROPHYASSOCIATED WITH POLYNEUROPATHY
SPAANS, F. and MIRANDOLLE, J.F. State U n i v e r s i t y of Limburg, Maastricht, and De Wever Hospital, Heerlen, The Netherlands Report on a f a m i l y of which a l l subjects with myotonic dystrophy appeared to have moderate to pronounced impairment of motor and sensory nerve conduction. Some of the younger cases only showed marked slowing of nerve conduction. Similar findings have been reported by Hausmanowa-Petrusewicz et al. ( i n S e r r a t r i c e and Roux: Peroneal atrophies and related disorders, Masson, New York, 1977) in 10 patients, a l l men, 8 of which came from 4 f a m i l i e s . In our family females were affected as well as males. The findings could not be ascribed to an incidental combination of two diseases.
F300 ASPECTSOF THE NORMALAND ABNORMALMOTORUNITS OBTAINED BY USING DIFFERENT EMG METHODS STALBERG,E., Dept. of Neurophysiology, U n i v e r s i t y Hospital, Uppsala, Sweden Depending on the EMG electrode size d i f f e r e n t motor u n i t parameters are obtained. The SiNgle Eibre EMG (SFEMG) gives information about i n d i v i d u a l muscle
S176
f i b r e s , motor end-plates and the local arrangement of muscle f i b r e s within the motor u n i t . The concentric needle EMG (CNEMG) records a c t i v i t y from only a f r a c t i o n of the motor u n i t. By Macro EMG, a nonselective recording from the main part of the motor u n i t , information is retrieved about the size and number of muscles fibres in the e n t i r e motor u n i t. Since the methods r e f l e c t d i f f e r e n t motor u n i t parameters they may change independently in pathology. In reinnervation the f i b r e density (FD), the duration of the CNEMG potential and the Macro MUP amplitude are increased. In myopathies FD is increased, the CNEMG potential is shorter and the Macro EMG mainly unchanged. In e.g. ALS on the other hand the FD is increased, the CNEMGpot ent ial is prolonged but he Macro EMG although usually increased may be normal or even decreased. These discrepancies occur i f the changes within the motor u n i t t e r r i tory are heterogeneous. The combined use of these methods is p a r t i c u l a r l y valuable in s i t u a t i o n s of dynamically changing motor units. I t may improve f u r t h e r the understanding of pathophysiological processes in neuromuscular disorders.
F301 THE ELECTROPHYSIOLOGICALCHANGESOF PERIPHERAL NERVES IN HEMIPLEGIA STEFANCIC,M., R e h a b i l i t a t i o n I n s t i t u t e , Ljubljana, Yugoslavia Electrophysiological changes in both the ulnar and median nerves of the upper extremities were studied in 3o patients with h e m i p l e g i a . S t a t i s t i c a l l y s i g n i f i cant differences in latency of the F-wave, extended on the affected side, and in amplitude of the maximum M-wave, lowered on the affected side were found between the c l i n i c a l l y affected and unaffected extremities. Those differences were not in any c o r r e l a t i o n with the patients' age, period of time from onset of disease to measurements, or the skin temperature of the extremity. Semiq u a n t i t a t i v e determination of the amplitude of the F-wave indicated a higher amplitude and more stable response on the affected side during the period of several months or years fo l l o w i n g onset of disease. The terminal conduction times and motor conduction v e l o c i t i e s of the ulnar nerve, latencies and amplitudes of the electroneurogram, as well as conduction v e l o c i t i e s of the sensory fibres of the median nerve d i d n ' t show any s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n ces between the two extremities. I t is believed that cessation of inflow of impulses and of the trophic influence from the higher centers of the central nervous system is responsible fo r changes a f f e c t i n g motor neurons of the anter i o r horns of the spinal cord p a r t i c u l a r l y those with the fastest conduction.
F302 A REALISTIC DESCRIPTION OF VELOCITY DISTRIBUTIONSIN COMPOUNDNERVE ACTION POTENTIALS STEGEMAN,D. andSCHOONHOVEN,R., Dept. of Clin. Neurophysiology and Dept. of Medical Physics and Biophysics, University of Nijmegen, The Netherlands The diameters of myelinated f i b r e s in a nerve are usually expressed in a diamet e r histogram. From such a histogram a d i s t r i b u t i o n of f i b r e v e l o c i t i e s can be calculated assuming a known r e l a t i o n between f i b r e size and v e l o c i t y . The a r r i val times of the i n d i v i d u a l f i b r e action p o t e n t i a l s at the s i t e of recording in a compound action potential (CAP) can be determined on the basis of that distribution. The central theme here is the question how a given diameter histogram should be converted to the belonging a r r i v a l time d i s t r i b u t i o n of the constituent f i b r e s . This is an important aspect in modelling CAPs, since unproper choices can lead to f a i l u r e s in the correspondence between measured and simulated CAPs. When
F298 AUTONOMICDYSFUNCTION IN UREMIA SOLDERS, G. and PERSSON, A.~Dept. of C l i n . Neurophysiology, Huddinge, Univ. Hospital, Sweden Symptoms of autonomic f a i l u r e are common among patients with renal f a i l u r e . In order to establish r e l i a b l e methods to study these complications, we have studied the R-R v a r i a t i o n s in patients on regular haemodialysis. METHODS: The R-R v a r i a t i o n s in the ECG were recorded as consecutive R-R i n t e r v a l s and the v a r i a t i o n s r e l a t i v e to mean R-R i n t e r v a l were calculated for one minute periods during normal breathing (N%) and during deep breathing (D%) as described e a r l i e r (Acta Neurol. Scand~. The N% and D% values were compared to age-matched controls. Furthermore MCV and SCV in the median, peroneal and sural nerves and the v i b r a t i o n thresholds d i s t a l sites were recorded with conventional technique. RESULT: Patients with chronic renal f a i l u r e showed greatly impaired R-R v a r i ations. Most patients had also signs of d i f f u s e neuropathy. The preliminary r e s u l t s indicate that there was a covariation between autonomic and peripheral neuropathy. DISCUSSION: The R-R v a r i a t i o n s are believed to depend on an i n t a c t vagal r e f l e x arc. E a r l i e r we have shown t h i s test to be a simple and r e l i a b l e test on autonomic dysfunction provided that age-matched controls are used. The present study shows that autonomic f a i l u r e is a common f i n d i n g in patients on haemodialysis due to renal f a i l u r e . We believe t h i s test to be of great value in the c l i n i c a l evaluation of uremic patients and in the preoperative i n v e s t i gation before k i d n e y - t r a n s p l a n t a t i o n . Involvement of cardiac nerves probably raise the r i s k of cardio-vascular complications during surgery.
F299 MYOTONICDYSTROPHYASSOCIATED WITH POLYNEUROPATHY
SPAANS, F. and MIRANDOLLE, J.F. State U n i v e r s i t y of Limburg, Maastricht, and De Wever Hospital, Heerlen, The Netherlands Report on a f a m i l y of which a l l subjects with myotonic dystrophy appeared to have moderate to pronounced impairment of motor and sensory nerve conduction. Some of the younger cases only showed marked slowing of nerve conduction. Similar findings have been reported by Hausmanowa-Petrusewicz et al. ( i n S e r r a t r i c e and Roux: Peroneal atrophies and related disorders, Masson, New York, 1977) in 10 patients, a l l men, 8 of which came from 4 f a m i l i e s . In our family females were affected as well as males. The findings could not be ascribed to an incidental combination of two diseases.
F300 ASPECTSOF THE NORMALAND ABNORMALMOTORUNITS OBTAINED BY USING DIFFERENT EMG METHODS STALBERG,E., Dept. of Neurophysiology, U n i v e r s i t y Hospital, Uppsala, Sweden Depending on the EMG electrode size d i f f e r e n t motor u n i t parameters are obtained. The SiNgle Eibre EMG (SFEMG) gives information about i n d i v i d u a l muscle
S176
f i b r e s , motor end-plates and the local arrangement of muscle f i b r e s within the motor u n i t . The concentric needle EMG (CNEMG) records a c t i v i t y from only a f r a c t i o n of the motor u n i t. By Macro EMG, a nonselective recording from the main part of the motor u n i t , information is retrieved about the size and number of muscles fibres in the e n t i r e motor u n i t. Since the methods r e f l e c t d i f f e r e n t motor u n i t parameters they may change independently in pathology. In reinnervation the f i b r e density (FD), the duration of the CNEMG potential and the Macro MUP amplitude are increased. In myopathies FD is increased, the CNEMG potential is shorter and the Macro EMG mainly unchanged. In e.g. ALS on the other hand the FD is increased, the CNEMGpot ent ial is prolonged but he Macro EMG although usually increased may be normal or even decreased. These discrepancies occur i f the changes within the motor u n i t t e r r i tory are heterogeneous. The combined use of these methods is p a r t i c u l a r l y valuable in s i t u a t i o n s of dynamically changing motor units. I t may improve f u r t h e r the understanding of pathophysiological processes in neuromuscular disorders.
F301 THE ELECTROPHYSIOLOGICALCHANGESOF PERIPHERAL NERVES IN HEMIPLEGIA STEFANCIC,M., R e h a b i l i t a t i o n I n s t i t u t e , Ljubljana, Yugoslavia Electrophysiological changes in both the ulnar and median nerves of the upper extremities were studied in 3o patients with h e m i p l e g i a . S t a t i s t i c a l l y s i g n i f i cant differences in latency of the F-wave, extended on the affected side, and in amplitude of the maximum M-wave, lowered on the affected side were found between the c l i n i c a l l y affected and unaffected extremities. Those differences were not in any c o r r e l a t i o n with the patients' age, period of time from onset of disease to measurements, or the skin temperature of the extremity. Semiq u a n t i t a t i v e determination of the amplitude of the F-wave indicated a higher amplitude and more stable response on the affected side during the period of several months or years fo l l o w i n g onset of disease. The terminal conduction times and motor conduction v e l o c i t i e s of the ulnar nerve, latencies and amplitudes of the electroneurogram, as well as conduction v e l o c i t i e s of the sensory fibres of the median nerve d i d n ' t show any s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n ces between the two extremities. I t is believed that cessation of inflow of impulses and of the trophic influence from the higher centers of the central nervous system is responsible fo r changes a f f e c t i n g motor neurons of the anter i o r horns of the spinal cord p a r t i c u l a r l y those with the fastest conduction.
F302 A REALISTIC DESCRIPTION OF VELOCITY DISTRIBUTIONSIN COMPOUNDNERVE ACTION POTENTIALS STEGEMAN,D. andSCHOONHOVEN,R., Dept. of Clin. Neurophysiology and Dept. of Medical Physics and Biophysics, University of Nijmegen, The Netherlands The diameters of myelinated f i b r e s in a nerve are usually expressed in a diamet e r histogram. From such a histogram a d i s t r i b u t i o n of f i b r e v e l o c i t i e s can be calculated assuming a known r e l a t i o n between f i b r e size and v e l o c i t y . The a r r i val times of the i n d i v i d u a l f i b r e action p o t e n t i a l s at the s i t e of recording in a compound action potential (CAP) can be determined on the basis of that distribution. The central theme here is the question how a given diameter histogram should be converted to the belonging a r r i v a l time d i s t r i b u t i o n of the constituent f i b r e s . This is an important aspect in modelling CAPs, since unproper choices can lead to f a i l u r e s in the correspondence between measured and simulated CAPs. When