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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.

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.

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 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.

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.

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.

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.

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.

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 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.

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.