Search

Background: The aim of this study was to compare the electromyographic pattern in Becker muscular dystrophy (BMD) with that found in Duchenne muscular dystrophy (DMD)., Material and Method: Fourteen men with BMD and 51 boys with DMD were investigated. Proximal muscles were examined: m. biceps brachii (BB) and m. rectus femoris (RF). They were divided according to the clinical criteria in two groups: of those with slight changes (group AB) and of those with severe abnormalities (CD). As in the Part I of the paper our own method of Functional-QEMG was applied in the CNEMG examination., Results and Conclusions: Spontaneous activity (fibrillations, complex repetitive discharges) was equally frequent in BMD and DMD. Linked potentials were rather frequent in either group. Myopathic features such as MUAPs low amplitude and area, polyphasic shape were seen in either condition, but more marked in DMD than in BMD. Evaluation of IP recordings revealed that IP amplitude (amplitude size) is low in DMD already at the early stage of lesion but normal or only slightly diminished in BMD. It might perhaps suggest different degrees of lesion in type II MUs between the compared types of muscular dystrophy.

Background: The study was aimed to evaluate the EMG pattern in myopathy, in the muscles with early, slight abnormalities and in the muscles severely affected, and to analyze the sequence of abnormalities appearing with the progress of the impairment., Material and Method: Fifty one boys with Duchenne muscular dystrophy were studied. Ninety nine proximal muscles (biceps brachii and rectus femoris) were examined. According to clinical criteria (defective force, atrophy) the muscles were assigned to the group of slight changes (group AB: 50 muscles) and to the group of severe abnormalities (group CD: 49 muscles). An own method of Functional-QEMG was applied in the CNEMG examination., Results and Conclusions: The sensitivity of the method applied allowed the detection of myogenic changes even at the subclinical, oligosymptomatic (group AB) stage of impairment. The earliest EMG abnormality detected was an increased percentage of the polyphasic potentials, even if other MUAPs parameters remained normal. However at this stage already a decrease appeared of amplitude, area and MUAPs duration, along with the decrease of IP amplitude and amplitude size. An increase of IP density and a slight increase of number of stable-shaped potentials (simple, but more often polyphasic) was also seen which we believed to reflect the compensatory process. At the further stage, when compensating mechanisms were no longer possible, a dramatic decrease appeared of the IP amplitude, amplitude size and density and, sometimes, also a decrease in the number of stable-shaped potentials. The structural changes such as decrease of amplitude, area and MUAPs duration also progressed. These findings reflect in our study the sequence of EMG abnormalities in the successive stages of myogenic lesion.

Background: Hypoglycemia is an acute disturbance of energy, especially impacting the central nervous system, but direct influence on peripheral nervous function is not detected. The aim of the study was to establish the influence of hypoglycemic moderate and severe episodes on the function of peripheral nerves, hearing and visual pathway., Material and Methods: 97 children with type 1 diabetes (mean age 15.4+/-2.16 years, mean duration of diabetes 8.11+/-2.9 years, mean HbA1c 8,58+/-1.06%), at least 10 years old and with at least 3 years duration of diabetes, were included to study. Nerve conduction studies, visual (VEP) and auditory (ABR) evoked potentials were performed with standard surface stimulating and recording techniques. Moderate hypoglycemic episodes were defined as events of low glycemia requiring help of another person but without loss of consciousness and/or convulsions but recurrent frequently in at least one year. Severe hypoglycemia was defined as events with loss of consciousness and/or convulsions. Univariate ANOVA tests of significance or H Kruskal-Wallis test were used, depending on normality of distribution., Results: The subgroups with a history of hypoglycemic episodes had significant delay in all conduction parameters in the sural nerve (amplitude p<0.05, sensory latency p<0.05, and velocity p<0.005) and in motor potential amplitude of tibial nerve (p<0.005). In ABR wave III latency and interval I-III in subgroups with episodes of hypoglycemia (p<0,05) were significantly prolonged. In analyses of VEP parameters no differences were detected., Conclusions: The study showed influence of hypoglycemic episodes on function of all sural nerve parameters and tibial motor amplitude, and in ABR on wave III and interval I-III. Frequent moderate hypoglycemic episodes were strong risk factors for damage of the peripheral and central nervous systems, comparable with impact of several severe hypoglycemias.

A case is presented of a 34-year-old man who developed weakness of the proximal muscles of the extremities, particularly lower, slight myalgia, and vegetative symptoms (dryness in the mouth). Those symptoms progressed within a month. On examination weakness of the muscles of the extremities was found as well as weak tendon reflexes, slight atrophy of muscles of the arms and thighs and apokamnosis. Edrophonium test was slightly positive. Electrostimulation revealed changes typical of the Lambert-Eaton syndrome: low amplitude of the compound muscle action potential on single stimulus, decreasing amplitude of the subsequent responses to 3 Hz stimulation, marked facilitation on 30 Hz stimulation. Neoplastic etiology was excluded by chest X-ray and CT, as well as by bronchoscopy, abdominal and prostatic USG, and thyroid USG and scintigraphy. Antibodies to AChR were not found in the serum. The titre of the antibodies against voltage-gated calcium channels was highly positive which was decisive in the diagnosing of the Lambert-Eaton syndrome. The patient was treated with pyridostigmine, corticosteroids, cyclophosphamide and immunoglobulins. Ten years of follow-up have fully confirmed the diagnosis of a non-neoplastic Lambert-Eaton syndrome.

We retrospectively analyzed the course and outcome of pregnancy in a group of 26 women with myasthenia gravis. Premature births were noted in 7.9% of pregnancies, the rate of cesarean section was 15.8%. Neonatal myasthenia was observed in 10 children born by 5 women (16% of the mothers). There were three neonatal deaths: two due to neonatal myasthenia, one in a child born with multiple congenital anomalies. Transient exacerbation of MG symptoms was observed during four pregnancies (10.5%). MG is not associated with increased risk for MG patient and the newborn. Giving birth to one child with transient MG increases the risk of transient MG in consecutive pregnancies.

Background and Purpose: F-wave is a late response recorded from muscle elicited by electric impulse conveyed antidromically to alpha-motor neurons of the spinal cord. F-wave latency and frequency are assessed in routine electroneurography providing information of conduction in the proximal segment of the nerves. F-wave amplitude is rarely analyzed, while it could add valuable information on excitability of motor neurons in different disease states. This study was conducted to determine whether F-wave amplitude is indicative of the level of the peripheral nervous system lesion., Material and Methods: EMG recordings of 204 consecutive patients suspected of peripheral nerves system lesion were retrospectively analyzed. Based on the clinical diagnosis three groups were defined: neuropathy (N=100), myopathy (N=33), ALS (N=18), reference (musculoskeletal pain syndromes: N=53). F-wave amplitude and F/CMAP-ratio (CMAP-compound motor action potential) and their relation to parameters of impulse conduction in motor nerve fibers was analyzed., Results: Mean F/CMAP ratio was 11.1% in ALS, 5% in myopathy (p=0.008), 7.1% in neuropathies and 5.6% in the reference group. Giant F-wave (more than 10% of CMAP) was observed in 30% of nerves in ALS, 15% in neuropathy and 10% in myopathy (p=0.036). F-wave amplitude correlated significantly with CMAP amplitude in all groups, while F/CMAP ratio was inversely related to CMAP amplitude in ALS (r=-0.43, p<0.01) and neuropathy (r=-0.37, p<0.0001). F-wave frequency was similar in all groups and correlated with CMAP amplitude., Conclusions: F-wave amplitude is not indicative of the level of peripheral nervous system lesions. Giant F-wave is observed in neurogenic processes. It reflects an increase of motor unit size in the reinnervation process, but possibly also a change of excitability of motor neuron and its axon.

A study was made of the degree and sequence of neurophysiological changes during motor unit reorganisation in motor neuron disease (MND), spinal muscular atrophy (SMA), and prior polio. Concentric needle EMG was used in conjunction with our own computerized EMG-LAB system. Motor unit action potential (MUAP) parameters were measured in 543 muscles on weak and maximum effort. MUAP amplitude and area were found to increase in the early stages of damage, declining to normal or subnormal values in the course of the disease. It was concluded that in MND there is a pathological sequence: denervation--reinnervation--terminal denervation. The increase in MUAP amplitude and area in the early stages of lesion, reflecting reinnervation, was much greater in SMA than MND and most marked in prior polio. The eventual decrease is an expression of terminal decompensation.

Myasthenic syndromes are a heterogeneous group of congenital or acquired disorders of neuromuscular junction. Despite major advance in genetics and molecular biology of disorders of neuromuscular junction, clinical diagnosis and choice of treatment largely depends on results of neurophysiological tests. Different protocols of repetitive nerve stimulation and single fibre EMG are indispensable in confirming neuromuscular junction defect, they can also give additional information on the level of abnormality and differentiate myasthenia gravis from Lambert-Eaton syndrome (pre- or postsynaptic defect). Characteristic features of repetitive nerve stimulation test e.g. repetitive response allow diagnosing congenital myasthenic syndromes such as slow channel syndrome or acetylcholine deficiency. Patophysiological basis of neurophysiological tests of neuromuscular transmission is presented. Different neurophysiological findings in cases of Lambert-Eaton myasthenic syndrome and congenital myasthenic syndromes are presented.

In classical quantitative analysis motor unit action potentials (MUAPs) parameters are useful in establishing diagnosis, but not in monitoring the functional status as expressed by clinical sings. This drawback is overcome by our new method called "Functional-QEMG", where the analysis is based on structural and functional changes of all acting motor units (MUs). The automatic classification of normal versus myogenic or neurogenic disorder together with the assessment of their severity is performed by special computer-assisted diagnostic procedures. The classification is based on individual MUAPs size (structure) and their functional properties determined in unique "Mapping-MUAP" program. This classification is further confirmed by the adequate to a given pathology the structural reorganisation of all acting MUs. In consequence theirs functional properties are changing as the compensatory mechanisms to generate the optimal force in structurally changed acting MUs. Thus, the effectiveness of compensatory process is used for quantitative assessment of severity of the disease from simultaneously recorded maximal effort pattern. Our experience during last ten years shown that such dynamical analysis is very useful in correlation with the clinical picture of examined patient to make the final conclusion of EMG investigation.

In diagnostics of ALS the electrophysiologic investigation should be able to evaluate two fundamental processes: the primary process of the loss of some motoneuros--denervation, and secondary process of reinnervation. The most important diagnostic methods include the quantitative electromyography (EMG) evaluating several parameters of the motor unit potential (MUP) and of the maximal effort pattern. The earliest features are the signs of spontaneous activity (denervation) and the elevation of MUP amplitude and area (reinnervation). Finding of spontaneous activity in the tongue muscles as well as in the paraspinal muscles is of great diagnostic value. SFEMG may early detect increased density of muscle fibres (FD) and jitter elongation as signs of recent reinnervation. Electroneurography is critical in differentiation against the multifocal motor neuropathy with conduction block and other polyneuropathies. The aim of the electrophysiological investigations is also the evaluation of the intensity of lesion in the muscle investigated and, indirectly, the evaluation of the progress of the disease in serial studies. It might play a great role in prognosing and in monitoring of therapeutical trials. The abnormalities in the maximal effort pattern presenting as decrease of recording density and amplitude as well as of bioelectric activity indicate in the quantitative EMG a high degree of lesion. Those signs are accompanied by altered MUP parameters: decrease of MUP amplitude and area as compared with the former stages of reinnervation. Those signs express decompensation and denervation predominating over reinnervation. In SFEMG they present as FD decrease and in Macro-EMG as decrease of amplitude as compared to the reinnervation period. Serial investigations of amplitude of the potential resulting from supermaximal stimulation (CMAP), quantitative evaluation of the maximal voluntary isometric contraction (MVIC) and the assessment of the number of motor units (MUNE) are further valuable methods in monitoring of ALS progress.

The frequency of involvement of sensory pathways in motor neuron disease (MND) remains the matter of controversy. For this reason the purpose of the present work was to test how often sensory system involvement might be detected by somatosensory evoked potentials (SEP) studies and then to verify the presence of alteration of the sensory conduction and to detect the frequency of abnormalities of somatosensory peripheral, spinal, subcortical and cortical potentials in MND. SEP were tested after median nerve stimulation at the wrist, recorded from Erb's point, Ce2, Ce7 and scalp. Pearson's correlation coefficients test and Wilcoxon rank-sum test were used for statistical analysis. 74 patients (22 women and 52 men) were examined. Mean age of patients was 54.07 +/- 11.24 years; mean duration of the disease -19.25 +/- 15.87 months. SEP were abnormal in 39 of 74 patients (about 53%) whereas the sensory NCV in median nerve was abnormal in 14 of 74 patients (19%). The most frequent pattern of abnormalities consisted of the absence or delay of cortical responses. The mean values of SEP latencies (N9, N11, N13, N20 and P25) were significantly increased in MND patients (p < 0.05) as compared with controls. The N9 and N11 latencies correlated with the duration of the disease. The results of our study (concerning a large group of MND patients) suggest that the involvement of sensory pathways is not rare in MND.

Twenty myasthenic patients were followed up who had in the years 1981-1982 full clinical remission (no drugs, no symptoms), lasting at that time at least several years. However, in 19 of them neuromuscular transmission defects were then found by single fibre electromyography (SFEMG). We then concluded that true remissions did not exist in myasthenia (J. Neurol., 1985, 231, 331). Recently, we were able to evaluate those patients. One patient, who had full long lasting remission after thymomectomy, died at the age of 69 of myocardial infarction in the course of a myasthenic relapse. Another patient had a relapse, 20 years after thymoma extirpation. Two patients had recurrent fluctuating relapses of myasthenia. One patient, who had undergone thymectomy in his childhood, developed immune thrombocytopenic syndrome. SFEMG done in 12 patients showed abnormalities in 5 cases only (mean jitter elongation, increased percentage of potential pairs with blocking and jitter elongation more than 55 microseconds). In 7 remaining patients the catamnesis covering more than 14 years revealed full clinical and electrophysiological remission. Thus, repeated analysis of the group of myasthenic patients with remission has lead us to revise our former opinion that there are no true remissions, clinical and electrophysiological, in myasthenia. They certainly occur but in some patients normalization of the electrophysiological pattern appears only several years after they have become clinically asymptomatic.

Examination of the sympathetic skin response (SSR), a non-invasive method of studying conduction in the sympathetic nervous system was performed in 15 male patients with obstructive sleep apnea syndrome (OSAS) evaluated by polysomnography who were compared with 7 non-apneic snorers and 26 controls. The aim of the study was to assess sympathetic nervous system function in OSAS, to compare the results with those found in non-apneic heavy snorers, to define the pattern of abnormalities and to study the correlations between SSR results and polysomnographic parameters. In the OSAS group the mean hand latency was significantly longer than in non-apneic snorers and healthy subjects. The most characteristic pattern of abnormalities was an absence of a foot response found in 12 of 15 OSAS patients. There were no correlations between SSR abnormalities and polysomnographic parameters. The SSR method seems to be useful in assessment of the sympathetic nervous system, especially of those parts related to sudomotor function, in OSAS.

We performed clinical and electrophysiological studies in 42 children with hereditary motor and sensory neuropathy type I and II (HMSN I and HMSN II) and in 103 members of their families. In 24 families with HMSN I the conduction velocity and the latency were markedly changed in the nerves innervating the distal muscles (median, peroneal nerves), as well as proximal muscles (facial, axillary, and musculocutaneous nerves). The changes were uniform in all motor and sensory nerves studied in the particular patient. No nerve conduction worsening with age has been found in cross-sectional analysis. In patients with HMSN I the conduction velocity was impaired even when the clinical abnormalities were minimal. The degree of the conduction velocity slowing was uniform within majority of the families. Homogeneity of conduction velocity slowing in individuals with HMSN I regardless of clinical expression suggests a primary myelin defect as an underlying cause. In patients from 18 families with HMSN II slight changes in conduction velocity were found only in the nerves innervating the distal muscles, the latency of axillary and facial nerves was within normal range. We recommend examining conduction time in facial and axillary nerves as a useful procedure for differentiation between HMSN I and II, especially in families with borderline conduction values in the long nerves.

We performed clinical and electrophysiological studies in 42 children with hereditary motor and sensory neuropathy type I and II (HMSN I and II) and in 103 members of their families. In 24 families with HMSN I the conduction velocity and latency were markedly changed in the nerves innervating the distal muscles (median, peroneal nerves) as well as proximal muscles (facial, axillary and musculocutaneous nerves). The changes were uniform in all motor and sensory nerves studied in a particular patient. The intensity of changes was similar in members of their families even when the clinical abnormalities were minimal, thus the degree of conduction velocity slowing was uniform within families. In adults with HMSN I (group A i B) we found less marked slowing of nerve conduction as compared to children (group P), the difference being significant (p < 0.001). It may suggest a slow process of peripheral nerves maturation despite the existing morbid condition. In patients of 18 families with HMSN II slight changes in conduction velocity were found only in nerves innervating the distal muscles, more evident in legs (peroneal and sural nerves). Conduction time of facial, axillary and musculo-cutaneous nerves was normal. The values of nerve conduction were not changing with patients' age. We recommend examining conduction time in facial, axillary or musculocutaneous nerve as a useful procedure for differentiation between HMSN I and II, especially in families with borderline conduction values in the nerves innervating distal muscles.

Ten cases of myasthenia are presented in which dysphonia was the initial sign. Isolated signs of dysphonia continued for several months or years, presenting diagnostic difficulties. Eventually neurologic examination followed by electrophysiological investigation (classical repetitive nerve stimulation and single fibre EMG) as well as edrophonium test allowed proper diagnosis of myasthenia, then confirmed by the clinical course. A possible diagnosis of myasthenia should be taken into consideration in cases with isolated dysphonic signs of uncertain origin.

Our material comparises 105 patients (62 men and 43 women) aged 26-73 years with amyotrophic lateral sclerosis (ALS). EMG examination confirmed the diagnosis of multilevel lesion of spinal motor neurons. Clinically, 94 of them had classical ALS, 3 had primary bulbar palsy (PBP), 6 had primary motor spinal atrophy (PSMA), and 2 had primary lateral sclerosis (PLS). Disease duration was 18.1 month, on the average, ranging from 2-60 months. In all patients motor and sensory nerve conduction was studied in median, peroneal and sural nerves. Conduction velocity, distal latency, F-wave latency of motor nerves, amplitude of M response and of sensory potentials were evaluated. Abnormalities were found most often in the motor fibres of median nerve: lowering of the M response amplitude in 44% of nerves studied, slowing of conduction velocity and elongation of distal latency in ca. 30%, elongation of F-wave latency in 27%. In the peroneal nerve the changes were less frequent: 38%, 21%, and 3%, respectively. They were also less marked. In the sensory fibres of median nerve slowing of conduction velocity was found in 25% of nerves, in sural nerve in 11%. Some slight decrease of amplitude of sensory potentials was seen in those nerves. The results obtained indicate a possibility of peripheral nerve lesion in the course of ALS which must be remembered in clinical diagnosing.

We studied 78 patients with motor neuron disease (MND) using concentric needle electromyography. Analysis on weak and maximal effort was performed using our own, fully automated, computer method, EMG-LAB. In addition to the conventional parameters of single motor unit action potentials (MUAPs) and interference pattern, new criteria were applied: the range of the acting motor units and the functional recruitment order. A total of 375 muscles of MND patients and 120 control muscles were investigated. The electromyographic data were analyzed separately in five groups of muscles, classified A, B, C, D, and E according to their clinical condition. Those results allowed us to discern six neurophysiological stages (N(0,1,2,3,4,5)) from the early to the most advanced phase. It has been confirmed that reinnervation in MND is adequate to compensate for the loss of over 50% of motor neurons but it is only a transitory phase in the morbid course. At stages N(O-5), the electrophysiological data reflect structural and functional integrity of the functioning motor units. Evaluation of not only single MUAPs but also of the full range of acting motor units and their recruitment order allowed a deeper look into the underlying pathophysiological mechanisms.

The solely dysphonia symptom as atypical and relatively rare onset of myasthenia gravis is difficult to diagnose. We present 11 cases of myasthenia, where dysphonia was one and only one symptom of illness during several months to several years. The evidences of dysphonia were the fatigability and nasality of speech, as well as chronic hoarseness. The diagnosis of myasthenia was very difficult in this period and was often preceded by lengthy laryngological and neurological examination. In our paper we present the criteria proper for myasthenia diagnosis in which repetitive electrostimulation test and high-sensitive SFEMG method are used.

We have sought associations with the muscle acetylcholine receptor alpha-subunit gene (CHRNA1) in autoimmune myasthenia gravis (MG) patients from three ethnic groups; Caucasians and South Africans of Black and Mixed-Ancestry. We found a significant association with the HB*15 CA repeat allele in unrelated Black myasthenics (n = 18; RR = 2.85; pX2 = 0.04) compared with 52 ethnically matched controls. A family-based association study and linkage analysis in Caucasian simplex and multiplex families supported a positive association at this locus with the longer alleles, including HB*14 to *18. However, no significant cosegregation of the disease with the HB alleles could be demonstrated in affected sib pairs. Our results suggest that the CHRNA1 locus harbours a minor susceptibility gene for developing MG, though we cannot rule out linkage disequilibrium with another major gene locus on chromosome 2.

Eleven patients with generalized myasthenia (type 2b and 3) were studied in whom thymectomy (9 cases) and/or oral steroids did not result in satisfactory improvement. Methylprednisolone was given once a day in an iv slow infusion for five consecutive days (30 mg/kg). In 7 cases this therapy was followed by oral prednisone and/or azathioprine, in 4 cases methylprednisolone infusions were repeated. In all patients a good clinical improvement was achieved immediately after the last infusion or several weeks later. SF EMG examination showed pathological jitter before methylprednisolone treatment in all patients. In 5 of them after therapy the abnormalities in SF EMG were less marked, in 6 patients their intensity did not change, despite good clinical improvement.

Three cases are presented of familial myasthenia gravis: two sisters and their cousin. Healthy members of this family were also examined. Myasthenia gravis was diagnosed on the ground of the clinical and electrophysiological examination (decrement test and SF EMG with jitter evaluation) as well as of the immunological tests (anti AChR antibodies and HLA antigens B8, DR3). Several healthy relatives of myasthenic patients had HLA B8 and DR3 antigens and/or presented neuromuscular transmission disturbances detected on SF EMG examination. Occurrence of myasthenia in two or more members of a family can be a risk factor for the remaining members.

Subjective and objective sensory threshold (Ts, T(ap)) was measured in the sensory fibres of the median and the sural nerves of patients with diabetic neuropathy, Guillain-Barre-Strohl syndrome, hereditary motor and sensory neuropathy (HMSN I and II) as well as in the carpal tunnel syndrome (CNS). A very marked increase of the Ts was found in HMSN I in both nerves investigated. In HMSN II significant increase of Ts were present only in the sural nerve. In CTS significant increase of Ts was found. Measurements of Ts may be useful in the evaluation of the intensity of sensory nerves lesion.

The single fibre EMG differences during motor axonal stimulation at different firing rates were studied in myasthenic patients: 15 with, and 15 without thymoma. 10 healthy volunteers were also examined. Conventional repetitive stimulation EMG as well as SFEMG during weak voluntary contraction and on 10 and 20Hz stimulation was performed in every patient. The mean jitter in the control group was 30 microseconds on voluntary contraction and about 22 microseconds at 10 as well as at 20 Hz stimulation. In both groups of myasthenic patients under consideration SFEMG on voluntary contraction detected neuromuscular transmission disturbances of various degree. The results obtained at motor axonal stimulation (10 and 20 Hz) were unhomogeneous. In both groups jitter seemed to be slightly shorter at higher (20 HZ) frequency stimulation, probably due to facilitation but differences were insignificant.

The material comprises 10 cases with a history of Guillain-Barré syndrome within the last several years in which clinical investigations failed to demonstrate any abnormalities. Electrophysiological investigations of peripheral nerves including conduction velocity in motor fibres--maximal and minimal, sensory fibres, standardized terminal latency--showed presence of changes evidencing slight but persisting subclinical lesion to peripheral nerves, especially in subjects affected in early childhood. Slowing of conduction involved motor as well as sensory fibres in these nerves and was more pronounced in the ulnar nerve than in the remaining nerves (peroneal, axillary, musculocutaneous and facial).

By the electrophysiological methods such as supramaximal stimulation and single-fibre EMG (SF EMG) 13 children with myasthenia were studied. In only one case the results of both tests were normal. These findings confirm the presence of subclinical disturbances of neuromuscular transmission in most cases of myasthenia during remission. This may be of practical importance in the treatment of myasthenic patients.

A case report is presented of episodic hypersomnia with bouts of several days duration. The authors discuss various clinical syndromes with sleep disorders with particular consideration of the Kleine-Levin syndrome.

Single fiber electromyography with jitter measurements and blocking evaluation was used for investigating 23 myasthenic patients, their 29 healthy relatives, coming from 10 families, and a control group of 10 subjects. Blocking was never seen in the healthy controls, and the jitter averaged some 30 microsec. Blocking was present in the myasthenic patients in 25.4% of the recorded potential pairs and there was a pathological jitter, which often extended over a few hundred microsec. The records of ten healthy relatives of patients were suggestive of slight but unquestionable abnormalities of neuromuscular transmission, viz. blocking and a jitter of over 60 microsec or more. The results demonstrate subclinical derangements of neuromuscular transmission in families of myasthenic patients, which points to a familial factor as involved in the pathomechanism of the disease.

In 20 cases of acute Guillain-Barré syndrome (including 4 recurrent cases the conduction velocity was measured in the nerves: facial, axillary, musculocutaneous, peroneal, sural and ulnar (motor and sensory). In the long nerves the maximal as well as minimal conduction velocity was determined. At the peak of development of clinical manifestations all electrophysiological parameters differed from the normal values, in particular, significant changes were found in long nerves (complete parallelism was found between the velocity of conduction and end latency). In the first stage of regression of clinical manifestations the electrophysiological parameters continued to show an increased abnormalities, only later they approached the normal values. Sensory conduction was disturbed in an equal degree as the motor conduction despite absence of clinical sensory disturbances. In recurrent cases slowing down of conduction was much more striking and persisted also during remission. In all studied cases independently of the character and course of the disease there was no correlation between the clinical state and the changes in the determined electrophysiological parameters.