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Motor unit action potential shape — Its variability studied by means of computer simulation
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one of the eight classes (PI - P8) of t h i s corpus that have emerged from dynamic clusters algorithm.Thus on l i n e diagnosis may be considered in terms of d i s t r i b u t i o n in the corpus since 80% of signals obtained from myopaths are assigned in P4,5 and 6 and 18% from healthy. When applied to female r e l a t i v e s of DUCHENNE dystrophy, the method allowed to detect a l l the d e f i n i t e c a r r i e r s whatever the CPK level was. Among the possible c a r r i e r s , a l l the so called "gonadic mutation" presented a normal d i s t r i b u t i o n . In addition, some young g i r l s presented a s i g n i f i c a n t excess in P4, 5 or 6. I t is yet too early to precise the r e l i a b i l i t y l i m i t s of the method, but henceforward, i t proves i t s e l f to be an i n t e r e s t i n g complement in detecting c a r r i e r s of X-linked muscular dystrophy since i t well d i f f e r e n t i a t e s t h i s population from a control one (p o.ool on the whole P456 or Pl, 4, 5, 7 separately). In p a r t i c u l a r , the MUAP from the former appear b r i e f e r and smaller.
F251 SHORTENINGREACTIONS OF THE WRIST MUSCLES IN NORMAL, HEMIPLEGIC AND PARKINSONIAN SUBJECTS PINNELLI,P. l and VILLANI,A.# I. Neurological C l i n i c , U n i v e r s i t y of Milan; 2. N e u r o r e h a b i l i t a t i o n , Cl. Lavoro Foundation, Veruno (Novara), I t a l y Angular displacement, v e l o c i t y of displacement, applied torque and EMG of f l e xor and extensor w r i s t muscles have been measured in lo normal, in 15 hemiplegic and in 15 parkinsonian subjects. The forearm and upper arm were s t a b i l i z e d on an adjustable support while the hand was s t a b i l i z e d on a lever in an i n t e r mediate position between pronation and supination. Normal subjects: Shortening reactions were constantly found in extensor muscles and occurred more often at the end of 45 ° passive extension of the w r i s t (IEMG mean value: 35~V.sec). Shortening reactions in w r i s t f l e x o r s appeared only with previous moderate voluntary innervation in 20% of t r i a l s . Hemiplegic subjects: Shortening reactions of the extensors were not e l i c i t e d in the presence of increased s t i f f n e s s and tonic stretch reflexes of the f l e x o r muscles. Their reappearance was found to be f a c i l i t a t e d by e l e c t r i c a l stimul a t i o n of extensor muscles and positional t r a i n i n g . Parkinsonian subjects: Shortening reactions were found to be increased in the extensor muscles (IEMG: 50 ~V.sec) with f u r t h e r enhancement (IEMG:8o~V.sec) by previous voluntary innervation of the same muscles. L-Dopa treatment in some patients enhanced these reactions even when the tonic stretch reflexes were greatly reduced.
F252 MOTORUNIT ACTION POTENTIAL SHAPE - ITS VARIABILITY STUDIED BY MEANS OF COMPUTER SIMULATION PIOTRKIEWICZ M, MILLER-LARSSON A, I n s t i t u t e of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, u l . KRN 55, Warsaw, Poland The purpose of the study was to show the effects of d i f f e r e n t factors, variable during an experiment, on the shape of MUAP. The new description of SFAP shape has been used, being a conjunction of two function of type t2 V(t,r) = (V2(r)-bi(r)t2)ex p (-~i~)
S153
one f o r t ( O ( b l , S l ) and another f o r t>O(b3,s3), where t is time, r - electrodet o - f i b r e distance, and V2 - amplitude of 2nd phase. Coefficients of functions were chosen so as to f i t the dependences of i n d i v i d u a l parameters of SFAP on distance, r . These dependences were based on the r e s u l t s of experiments of Ekstedt, 1964 (for short distances) and of modelling of M i l l e r - L a r s s o n , 1981 ( f o r long distances). D i s t r i b u t i o n of muscle f i b r e s on the MU t e r r i t o r y was generated by a computer on the basis of M i l l e r - L a r ~ o n ' s model (1980) and " e l e c t r o d e - t o - f i b r e " d i s t a n c e s were determined f o r d i f f e r e n t electrode positions in respect to MU t e r r i t o r y . The neuromuscular j i t t e r has been shown to influence much more the amplitude, than the time parameters of MUAP. The electrode displacements have the more pronounced e f f e c t , the smaller is the electrode. They also influence more the amplitude parameters of MUAP. Therefore, the number and order of local maxima, and t h e i r time r e l a t i o n s are the least variable features of MUAP shape.
F253 CHANGESIN THE H-REFLEX DURING A PREPARATORYBRAIN POTENTIAL IN HEMIPARETICS WITH A FOCAL ISCHAEMIC BRAIN LESION PODIVINSKY F, JERGELOVAM, BARTKO D~ I n s t i t u t e of Normal and Pathological Physiology, Centre of Physiological Sciences, Slovak Academy of Sciences, B r a t i s l a v a , CSSR Our study involved a t o t a l of 26 hemiparetic patients. Ischaemic focus was found l o c a l i z e d c o r t i c a l l y 15 times, deep~ubcortically (thalamus, mesencephalon) 11 times. Use was made of a method that permits simultaneous recording of changes both of c o r t i c a l macropotentials appearing in r e l a t i o n with preparation f o r voluntary movement, and also of e x c i t a b i l i t y of the H-reflex. Hemiparetic patients with l i g h t focal c o r t i c a l lesion had only a s l i g h t l y depressed amplitude of the preparatory brain potential (over the affected hemisphere). In those with a deeper subcortical ischaemic lesion we found an i n s i g n i f i c a n t to inappreciable preparatory potential b i l a t e r a l l y . A s t r i k i n g deformation t i l l desorganization of the preparatory brain potential is probably r e l a t ed to an impairment of the generator of the slow preparatory potential in the deeper structures of the brain and a d i s r u p t i o n of cooperation in the complex cerebral cortex - middle thalamus. The above deep subcortical brain structures simultaneously control and modulate both the processes (the preparatory potent i a l and the H-reflex) being activated by impulses taking place in the longlooped r e f l e x arches during e l e c t r i c a l stimulation of n. t i b i a l i s . This i n t e r pretation of our r e s u l t s is in agreement with the f i n d i n g of a r e l a t i v e l y s a t i s f a c t o r y f a c i l i t a t i o n of the H-reflex in c o r t i c a l focal brain ischaemia, and of the absence of f a c i l i t a t i o n of the H-reflex in deeper subcortical i s chaemic f o c i .
F254 PERIPHERALNERVE CONDUCTIONFUNCTION, VITAMIN Bl SERUMLEVEL AND VISUAL EVOKED POTENTIAL IN CHRONIC ALCOHOLICS POSTHUi4A j 1 , VISSER SL~ I p s y c h i a t r i c Hospital Dennenoord, Zuidlaren; 2Academic Hospital, Free U n i v e r s i t y , Amsterdam, The Netherlands Polyneuropathy is a common complication in alcohol patients There is evidence that thiamine deficiency plays an important r o l e . previous VEP study carried out on Korsakow patients showed abnormal long Ploo latency i f evoked by pattern reversal. Not clear is whether an abnormal VEP in a l c o h o l i c patients is due to neuropathy or brain-damage. The study was carried out on 7o chronic alcoholics
one of the eight classes (PI - P8) of t h i s corpus that have emerged from dynamic clusters algorithm.Thus on l i n e diagnosis may be considered in terms of d i s t r i b u t i o n in the corpus since 80% of signals obtained from myopaths are assigned in P4,5 and 6 and 18% from healthy. When applied to female r e l a t i v e s of DUCHENNE dystrophy, the method allowed to detect a l l the d e f i n i t e c a r r i e r s whatever the CPK level was. Among the possible c a r r i e r s , a l l the so called "gonadic mutation" presented a normal d i s t r i b u t i o n . In addition, some young g i r l s presented a s i g n i f i c a n t excess in P4, 5 or 6. I t is yet too early to precise the r e l i a b i l i t y l i m i t s of the method, but henceforward, i t proves i t s e l f to be an i n t e r e s t i n g complement in detecting c a r r i e r s of X-linked muscular dystrophy since i t well d i f f e r e n t i a t e s t h i s population from a control one (p o.ool on the whole P456 or Pl, 4, 5, 7 separately). In p a r t i c u l a r , the MUAP from the former appear b r i e f e r and smaller.
F251 SHORTENINGREACTIONS OF THE WRIST MUSCLES IN NORMAL, HEMIPLEGIC AND PARKINSONIAN SUBJECTS PINNELLI,P. l and VILLANI,A.# I. Neurological C l i n i c , U n i v e r s i t y of Milan; 2. N e u r o r e h a b i l i t a t i o n , Cl. Lavoro Foundation, Veruno (Novara), I t a l y Angular displacement, v e l o c i t y of displacement, applied torque and EMG of f l e xor and extensor w r i s t muscles have been measured in lo normal, in 15 hemiplegic and in 15 parkinsonian subjects. The forearm and upper arm were s t a b i l i z e d on an adjustable support while the hand was s t a b i l i z e d on a lever in an i n t e r mediate position between pronation and supination. Normal subjects: Shortening reactions were constantly found in extensor muscles and occurred more often at the end of 45 ° passive extension of the w r i s t (IEMG mean value: 35~V.sec). Shortening reactions in w r i s t f l e x o r s appeared only with previous moderate voluntary innervation in 20% of t r i a l s . Hemiplegic subjects: Shortening reactions of the extensors were not e l i c i t e d in the presence of increased s t i f f n e s s and tonic stretch reflexes of the f l e x o r muscles. Their reappearance was found to be f a c i l i t a t e d by e l e c t r i c a l stimul a t i o n of extensor muscles and positional t r a i n i n g . Parkinsonian subjects: Shortening reactions were found to be increased in the extensor muscles (IEMG: 50 ~V.sec) with f u r t h e r enhancement (IEMG:8o~V.sec) by previous voluntary innervation of the same muscles. L-Dopa treatment in some patients enhanced these reactions even when the tonic stretch reflexes were greatly reduced.
F252 MOTORUNIT ACTION POTENTIAL SHAPE - ITS VARIABILITY STUDIED BY MEANS OF COMPUTER SIMULATION PIOTRKIEWICZ M, MILLER-LARSSON A, I n s t i t u t e of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, u l . KRN 55, Warsaw, Poland The purpose of the study was to show the effects of d i f f e r e n t factors, variable during an experiment, on the shape of MUAP. The new description of SFAP shape has been used, being a conjunction of two function of type t2 V(t,r) = (V2(r)-bi(r)t2)ex p (-~i~)
S153
one f o r t ( O ( b l , S l ) and another f o r t>O(b3,s3), where t is time, r - electrodet o - f i b r e distance, and V2 - amplitude of 2nd phase. Coefficients of functions were chosen so as to f i t the dependences of i n d i v i d u a l parameters of SFAP on distance, r . These dependences were based on the r e s u l t s of experiments of Ekstedt, 1964 (for short distances) and of modelling of M i l l e r - L a r s s o n , 1981 ( f o r long distances). D i s t r i b u t i o n of muscle f i b r e s on the MU t e r r i t o r y was generated by a computer on the basis of M i l l e r - L a r ~ o n ' s model (1980) and " e l e c t r o d e - t o - f i b r e " d i s t a n c e s were determined f o r d i f f e r e n t electrode positions in respect to MU t e r r i t o r y . The neuromuscular j i t t e r has been shown to influence much more the amplitude, than the time parameters of MUAP. The electrode displacements have the more pronounced e f f e c t , the smaller is the electrode. They also influence more the amplitude parameters of MUAP. Therefore, the number and order of local maxima, and t h e i r time r e l a t i o n s are the least variable features of MUAP shape.
F253 CHANGESIN THE H-REFLEX DURING A PREPARATORYBRAIN POTENTIAL IN HEMIPARETICS WITH A FOCAL ISCHAEMIC BRAIN LESION PODIVINSKY F, JERGELOVAM, BARTKO D~ I n s t i t u t e of Normal and Pathological Physiology, Centre of Physiological Sciences, Slovak Academy of Sciences, B r a t i s l a v a , CSSR Our study involved a t o t a l of 26 hemiparetic patients. Ischaemic focus was found l o c a l i z e d c o r t i c a l l y 15 times, deep~ubcortically (thalamus, mesencephalon) 11 times. Use was made of a method that permits simultaneous recording of changes both of c o r t i c a l macropotentials appearing in r e l a t i o n with preparation f o r voluntary movement, and also of e x c i t a b i l i t y of the H-reflex. Hemiparetic patients with l i g h t focal c o r t i c a l lesion had only a s l i g h t l y depressed amplitude of the preparatory brain potential (over the affected hemisphere). In those with a deeper subcortical ischaemic lesion we found an i n s i g n i f i c a n t to inappreciable preparatory potential b i l a t e r a l l y . A s t r i k i n g deformation t i l l desorganization of the preparatory brain potential is probably r e l a t ed to an impairment of the generator of the slow preparatory potential in the deeper structures of the brain and a d i s r u p t i o n of cooperation in the complex cerebral cortex - middle thalamus. The above deep subcortical brain structures simultaneously control and modulate both the processes (the preparatory potent i a l and the H-reflex) being activated by impulses taking place in the longlooped r e f l e x arches during e l e c t r i c a l stimulation of n. t i b i a l i s . This i n t e r pretation of our r e s u l t s is in agreement with the f i n d i n g of a r e l a t i v e l y s a t i s f a c t o r y f a c i l i t a t i o n of the H-reflex in c o r t i c a l focal brain ischaemia, and of the absence of f a c i l i t a t i o n of the H-reflex in deeper subcortical i s chaemic f o c i .
F254 PERIPHERALNERVE CONDUCTIONFUNCTION, VITAMIN Bl SERUMLEVEL AND VISUAL EVOKED POTENTIAL IN CHRONIC ALCOHOLICS POSTHUi4A j 1 , VISSER SL~ I p s y c h i a t r i c Hospital Dennenoord, Zuidlaren; 2Academic Hospital, Free U n i v e r s i t y , Amsterdam, The Netherlands Polyneuropathy is a common complication in alcohol patients There is evidence that thiamine deficiency plays an important r o l e . previous VEP study carried out on Korsakow patients showed abnormal long Ploo latency i f evoked by pattern reversal. Not clear is whether an abnormal VEP in a l c o h o l i c patients is due to neuropathy or brain-damage. The study was carried out on 7o chronic alcoholics