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Hypokalemic periodic paralysis: electrophysiologic and contractile properties of intercostal muscle
S163 of motor u n i t p o t e n t i a l s were not s i g n i f i c a n t l y d i f f e r e n t from those found in other species, but polyphasic p o t e n t i a l s were more numerous; the density of motor u n i t s was proportional to the strength of muscular contractions. In Mg++DEFICIENT RATS the three forms of t e t a n i c b i o e l e c t r i c a c t i v i t y (rhythmic repet i t i v e and non r e p e t i t i v e , and complex EMG tracings) were observed. Stimulo-detection values are shown on the f o l l o w i n g table: Normal Rats 20th day.!
40th day
Distal latency (ms)0.277 Z 0.010 i 0.277 ± 0.037 Motor conduction v e l o c i t y (m/sec)
Mg++-Deficient Rats
20th day
I
1
40th day
0.429 ~ 0.0401 0.214 ± 0.040 I
20.52
~ 0.91 122.03, _+ 1.060
21.95
± 2.18 121.99
± 1.49
F274 REFLEX EMG AND THE INVESTIGATION OF CENTRAL NERVOUS FUNCTION DURING DEVELOPMENT ROWLANDSON, P.H., STEPHENS, J.A.*, Paediatric and EMG Research, Rayne I n s t i t u t e & *Sherrington School of Physiology, St. Thomas' Hospital, London SE1 7EH, England In normal adult subjects, modest e l e c t r i c a l stimulation of the d i g i t s produces marked r e f l e x modulation of ongoing voluntary muscle a c t i v i t y in upper and lower limb muscles. T y p i c a l l y , responses consist of one or two short latency spinal components followed by a prominent long latency e x c i t a t o r y component thought to involve a c t i v i t y in the dorsal columns, sensori-motor cortex and corticospinal t r a c t (1). In the new-born, responses are monophasic, cons i s t i n g only of a powerful e x c i t a t o r y r e f l e x at spinal latency (2,3). Long latency components do not appear u n t i l the second year of l i f e (2). In some muscles, such as f i r s t dorsal interosseous, these components may mot appear u n t i l even l a t e r . Changes in amplitude of the d i f f e r e n t components of the cutaneous r e f l e x continue u n t i l about 10 years. Gradually, responses change from being dominated by short latency to being dominated by long latency components. We conclude that maturation of central nervous r e f l e x function continues during childhood and in some children does not reach maturity u n t i l puberty (4). I . Jenner, J.R. & Stephens, J.A. (1982), J. P h y s i o l . , 333, 405-419 2. I s s l e r , H. & Stephens, J.A. (1983), J. Physiol., 335, 643-654 3. Crum, J.E. & Stephens, J.A. (1982), J. P h y s i o l . , 332, 30-31 P. 4. Rowlandson, P.H. & Stephens, J.A. (1983). J. Physiol. Proceedings.
F275 HYPOKALEMICPERIODIC PARALYSIS: ELECTROPHYSIOLOGICAND CONTRACTILE PROPERTIES OF INTERCOSTALMUSCLE RDDEL RI) KOTHER G2) RICKE~ K3) LEHMANN-HORNF2), DENGLER R2 ) I) Dept. of Neurology, U n i v e r s i t y of Ulm; 2) Dept. of Neurology, Technical Univ e r s i t y of Munich; 3) Dept. of Neurology, U n i v e r s i t y of WUrzburg, FRG The reason f o r attacks of adynamia in hypokalemic periodic paralysis is s t i l l uncertain. P a r t i c u l a r l y unclear is the s i g n i f i c a n c e of the hypokalemia accompanying the p a r a l y t i c attacks. Using biopsied i n t e r c o s t a l muscle from 4 u n r e l a t ed patients we have tested in v i t r o the e f f e c t of low e x t r a c e l l u l a r potassium
S164
(Ke) on the muscle c o n t r a c t i l i t y . Simultaneously, we recorded resting membrane p o t e n t i a l , membrane conductance and e x c i t a b i l i t y under various e x t r a c e l l u l a r conditions. At normal Ke (3.5 mM), the resting potential was on average -75 mV, 5 to 15 mV lower than c o n t r o l . The t o t a l membrane conductance was normal, but the e x c i t a b i l i t y was reduced. Lowering of Ke to I mM caused a 50% reduction of isometric force and a reduction of the resting potential to a mean value of -50 mV. Control preparations produced f u l l force at Ke = I mM and hyperpolarized by 10 to 15 mV. The t o t a l membrane conductance in Ke = I mM was about the same f or diseased and control f i b e r s , and there was no i n d i c a t i o n of a reduced potassium conductance in f i b e r s from hypokalemic patients. The results show that lowering of the e x t r a c e l l u l a r potassium concentration plays an important role in hypokalemic periodic paralysis. A reduced potassium conductance can be excluded as a reason f o r the abnormal d e p o l a r i z a t i o n . The reasons f o r hypokalemia w i l l be discussed.
F276 CENTRALSOMATOSENSORYCONDUCTIONTIME AND SHORT LATENCY SOMATOSENSORY EVOKED POTENTIALS IN POSTTRAUMATICCOMA RUMPL, E., PRUGGER, M., GERSTENBRAND, F., HACKL, J . M . and PALLUA, A.~ Neurologische U n i v e r s i t ~ t s k l i n i k , A-6020 Innsbruck, Austria Short latency evoked p o t e n t i a l s (SEP) were e l i c t e d by stimulation of the median nerve at the wrist and recorded simultaneously from the neck and the c o n t r a l a t e r a l scalp in 44 comatose patients with signs of brain stem impairment due to head/brain i n j u r y . 34 patients were studied in acute coma on day 3-12 a f t e r in ju r y . Brain stem involvement was divided into secondary lesions due to supratentorial mass displacement and primary lesions due to d i r e c t violence to the brain stem. The centra~ somatosensory conduction time (CCT) was measured by subtracting the peak latency of N14 (neck) from that of N20 (scalp). The amplitude ratios (AR) N20/N14 were calculated for each trace. In coma due to suprat e n t o r i a l lesions CCT and AR were close to normals in patients with good outcome. CCT increased and AR decreased with the worsening of outcome both in acute and prolonged coma. Asymmetry or absence of SEP indicated moderate or severe d i s a b i l i t y outcome. Patients with t o t a l l y absent SEP died. In patients suffering from primary brain stem dysfunction prolonged CCT, asymmetric but also absent SEP were found in patients with good outcome. AR was generally low in these cases. Therefore even absent or severely distorted SEP should be interpreted cautiously, i f patients may suffer from primary brain stem involvement.
F277 DYNAMICCHANGESOF THE MOTORUNIT IN AMYOTROPHICLATERAL SCLEROSIS (ALS) RYDIN, E., STALBERG, E. and SANDERS, D., Depts. of Neurology and Clin. Neurophysiology, Univ. Hospital, Uppsala, Sweden, and Di~vision of Neurology, Duke University Medical Center, Durham, North Carolina, U.S.A. Variable degeneration and function loss of upper and lower motor neurones is c h a r a c t e r i s t i c of ALS. The ventral horn c e l l degeneration causes denervation, usually followed by reinnervation of s t r i a t e d muscles by sprouting.
40th day
Distal latency (ms)0.277 Z 0.010 i 0.277 ± 0.037 Motor conduction v e l o c i t y (m/sec)
Mg++-Deficient Rats
20th day
I
1
40th day
0.429 ~ 0.0401 0.214 ± 0.040 I
20.52
~ 0.91 122.03, _+ 1.060
21.95
± 2.18 121.99
± 1.49
F274 REFLEX EMG AND THE INVESTIGATION OF CENTRAL NERVOUS FUNCTION DURING DEVELOPMENT ROWLANDSON, P.H., STEPHENS, J.A.*, Paediatric and EMG Research, Rayne I n s t i t u t e & *Sherrington School of Physiology, St. Thomas' Hospital, London SE1 7EH, England In normal adult subjects, modest e l e c t r i c a l stimulation of the d i g i t s produces marked r e f l e x modulation of ongoing voluntary muscle a c t i v i t y in upper and lower limb muscles. T y p i c a l l y , responses consist of one or two short latency spinal components followed by a prominent long latency e x c i t a t o r y component thought to involve a c t i v i t y in the dorsal columns, sensori-motor cortex and corticospinal t r a c t (1). In the new-born, responses are monophasic, cons i s t i n g only of a powerful e x c i t a t o r y r e f l e x at spinal latency (2,3). Long latency components do not appear u n t i l the second year of l i f e (2). In some muscles, such as f i r s t dorsal interosseous, these components may mot appear u n t i l even l a t e r . Changes in amplitude of the d i f f e r e n t components of the cutaneous r e f l e x continue u n t i l about 10 years. Gradually, responses change from being dominated by short latency to being dominated by long latency components. We conclude that maturation of central nervous r e f l e x function continues during childhood and in some children does not reach maturity u n t i l puberty (4). I . Jenner, J.R. & Stephens, J.A. (1982), J. P h y s i o l . , 333, 405-419 2. I s s l e r , H. & Stephens, J.A. (1983), J. Physiol., 335, 643-654 3. Crum, J.E. & Stephens, J.A. (1982), J. P h y s i o l . , 332, 30-31 P. 4. Rowlandson, P.H. & Stephens, J.A. (1983). J. Physiol. Proceedings.
F275 HYPOKALEMICPERIODIC PARALYSIS: ELECTROPHYSIOLOGICAND CONTRACTILE PROPERTIES OF INTERCOSTALMUSCLE RDDEL RI) KOTHER G2) RICKE~ K3) LEHMANN-HORNF2), DENGLER R2 ) I) Dept. of Neurology, U n i v e r s i t y of Ulm; 2) Dept. of Neurology, Technical Univ e r s i t y of Munich; 3) Dept. of Neurology, U n i v e r s i t y of WUrzburg, FRG The reason f o r attacks of adynamia in hypokalemic periodic paralysis is s t i l l uncertain. P a r t i c u l a r l y unclear is the s i g n i f i c a n c e of the hypokalemia accompanying the p a r a l y t i c attacks. Using biopsied i n t e r c o s t a l muscle from 4 u n r e l a t ed patients we have tested in v i t r o the e f f e c t of low e x t r a c e l l u l a r potassium
S164
(Ke) on the muscle c o n t r a c t i l i t y . Simultaneously, we recorded resting membrane p o t e n t i a l , membrane conductance and e x c i t a b i l i t y under various e x t r a c e l l u l a r conditions. At normal Ke (3.5 mM), the resting potential was on average -75 mV, 5 to 15 mV lower than c o n t r o l . The t o t a l membrane conductance was normal, but the e x c i t a b i l i t y was reduced. Lowering of Ke to I mM caused a 50% reduction of isometric force and a reduction of the resting potential to a mean value of -50 mV. Control preparations produced f u l l force at Ke = I mM and hyperpolarized by 10 to 15 mV. The t o t a l membrane conductance in Ke = I mM was about the same f or diseased and control f i b e r s , and there was no i n d i c a t i o n of a reduced potassium conductance in f i b e r s from hypokalemic patients. The results show that lowering of the e x t r a c e l l u l a r potassium concentration plays an important role in hypokalemic periodic paralysis. A reduced potassium conductance can be excluded as a reason f o r the abnormal d e p o l a r i z a t i o n . The reasons f o r hypokalemia w i l l be discussed.
F276 CENTRALSOMATOSENSORYCONDUCTIONTIME AND SHORT LATENCY SOMATOSENSORY EVOKED POTENTIALS IN POSTTRAUMATICCOMA RUMPL, E., PRUGGER, M., GERSTENBRAND, F., HACKL, J . M . and PALLUA, A.~ Neurologische U n i v e r s i t ~ t s k l i n i k , A-6020 Innsbruck, Austria Short latency evoked p o t e n t i a l s (SEP) were e l i c t e d by stimulation of the median nerve at the wrist and recorded simultaneously from the neck and the c o n t r a l a t e r a l scalp in 44 comatose patients with signs of brain stem impairment due to head/brain i n j u r y . 34 patients were studied in acute coma on day 3-12 a f t e r in ju r y . Brain stem involvement was divided into secondary lesions due to supratentorial mass displacement and primary lesions due to d i r e c t violence to the brain stem. The centra~ somatosensory conduction time (CCT) was measured by subtracting the peak latency of N14 (neck) from that of N20 (scalp). The amplitude ratios (AR) N20/N14 were calculated for each trace. In coma due to suprat e n t o r i a l lesions CCT and AR were close to normals in patients with good outcome. CCT increased and AR decreased with the worsening of outcome both in acute and prolonged coma. Asymmetry or absence of SEP indicated moderate or severe d i s a b i l i t y outcome. Patients with t o t a l l y absent SEP died. In patients suffering from primary brain stem dysfunction prolonged CCT, asymmetric but also absent SEP were found in patients with good outcome. AR was generally low in these cases. Therefore even absent or severely distorted SEP should be interpreted cautiously, i f patients may suffer from primary brain stem involvement.
F277 DYNAMICCHANGESOF THE MOTORUNIT IN AMYOTROPHICLATERAL SCLEROSIS (ALS) RYDIN, E., STALBERG, E. and SANDERS, D., Depts. of Neurology and Clin. Neurophysiology, Univ. Hospital, Uppsala, Sweden, and Di~vision of Neurology, Duke University Medical Center, Durham, North Carolina, U.S.A. Variable degeneration and function loss of upper and lower motor neurones is c h a r a c t e r i s t i c of ALS. The ventral horn c e l l degeneration causes denervation, usually followed by reinnervation of s t r i a t e d muscles by sprouting.