Do true remissions in myasthenia really exist? An electrophysiological study.

To answer the question whether true remissions in myasthenia gravis occurred, 20 patients were studied with a history of evident, typical myasthenia but in full clinical remission. Two control groups served as a comparison: one of 10 healthy volunteers and the other of 10 patients with generalized, presently active myasthenia. In 17 of the 20 patients in remission single-fibre EMG (SFEMG) abnormalities were found, indicating some subclinical disturbances of neuromuscular transmission (in 3 cases the results were overtly pathological, in 11 cases moderately pathological, and in 3 cases slightly pathological). The abnormalities found in the remission group were much less distinct than those in the group with clinically symptomatic myasthenia. A case illustrates these findings: a man in full remission following thymoma extirpation in whom the SFEMG revealed subclinical disturbances of the neuromuscular transmission. Three weeks later a full clinical relapse occurred. The results obtained suggest that in the majority of patients the remissions are only apparently complete. A pathological jitter in a patient in remission calls for special attention: the patient must be spared any immunological stimuli such as vaccination, injections of sera, infections etc.; no drugs can be given which may increase the neuromuscular block; an immunosuppressive course of treatment should be considered; prognosis should be reconsidered.

Clinical, electrophysiological and immunological remissions after thymectomy in myasthenia gravis.

OBJECTIVES: Approximately 50% of patients treated with thymectomy have a chance for symptom-free life. However, immunological and neurophysiological abnormalities may be detected in patients with clinical remission. Although improvement usually parallels decrease in acetylcholine receptor antibody (AChRAb) levels and jitter values, there is a question what factors influence immunological and electrophysiological remission in a population of myasthenia gravis (MG) patients. METHODS: We analyzed retrospectively clinical data of 32 MG patients operated for generalized MG, followed-up at our department for 17.2 (4-31) years. They were in clinical remission for 12.8 (2-25) years. All of them had single fiber electromyograhy (SFEMG) of extensor digitorum communis muscle (EDC) muscle and estimation of AChRAb level at the end of follow-up. Their age at onset of MG was 17 years (6-48) and at thymectomy 19 (6.4-58) years. Tensilon test was positive in 30, repetitive nerve stimulation in 29 cases. RESULTS: Clinical remission was reached on average 4.2 years after thymectomy. SFEMG jitter value normalized in 60% of cases. AChRAb were negative only in 34% of patients. Jitter values correlated with AChRAb levels (P=0.006, r=0.5) but were not related to clinical factors. Only time to thymectomy correlated with time from thymectomy to clinical remission (P=0.001, r=0.5). CONCLUSIONS: Clinical remission is not always accompanied by normalization of SFEMG and AChRAb. Although normalization of neuromuscular transmission in patients with remission of MG is individual, short duration of MG before thymectomy increases the chance of early remission.

Pseudoselectivity of the neuromuscular block in ocular myasthenia: a SFEMG study.

The patients with pure ocular myasthenia presenting no signs of neuromuscular transmission defect on classical supramaximal repetitive stimulation were studied using SFMG method. Only those patients were selected to the study in whom the diagnosis of the ocular myasthenia was confirmed by the clinical criteria arranged so as to exclude ophthalmoplegia of the other nature. The series comprises 20 patients in whom the results of the supramaximal repetitive stimulation with the recording from the proximal muscles and with the evaluation of posttetanic phenomena were normal. SFEMG examination was performed in the clinically intact EDC muscle and in 17 patients an elongated jitter, sometimes with blocking was found. Among those three patients with normal results two were in full clinical remission, so there was only one patient presenting the symptoms of ocular myasthenia in whom the neuromuscular transmission defect was absent in the EDC. The results justify an admission that the neuromuscular block in ocular myasthenia is only apparently selective; in fact it concerns all the muscles with a different severity and may be detected if properly sensitive diagnostic methods are applied.

Muscular fatigability in mitochondrial myopathies. An electrophysiological study.

A frequent occurrence of ophthalmoplegia and muscle fatigability in mitochondrial myopathy (MAM) often makes its differential diagnosis from myasthenia rather difficult. Neuromuscular transmission was investigated in 9 patients with MAM, presenting marked fatigability. The aim of the study was to see whether there were any other causes of muscle fatigability in addition to the metabolic factors. Classical electrostimulation as well as the SFEMG, which is very sensitive in detecting neuromuscular transmission disorders, were used. The findings were far from uniform: we found normal neuromuscular transmission in 5 cases, in 3 patients we observed slight abnormalities of neuromuscular transmission, in 1 case neuromuscular transmission disturbances seemed to be of neurogenic origin. Our results allow an assumption that the causes of muscle fatigability in MAM are of a much more complex nature than it has been anticipated. They might depend not only on the metabolic disorders within the muscle fibre itself but also on the impaired function of the peripheral nerve or of the neuromuscular junction. All the mechanisms combined may also play a role, though in individual patients the contribution of particular factors responsible may vary.

[Disorders of neuromuscular transmission in hyperthyroidism]. / Zaburzenia transmisji nerwowo-miesniowej w nadczynnosci tarczycy.

Using the method of supramaximal electrostimulation 35 hyperthyroid patients with signs of muscle weakness or muscular fatigability were investigated and in over half the cases (53.5%) disturbances of neuromuscular transmission were found using sufficiently sensitive methods of activation. In nearly 70% of the tested muscles stimulated at 10 Hz a fall of the amplitude of successive potentials was observed. The analysis of these results suggested the following conclusions: 1. Muscular fatigability in hyperthyroidism is reflected in electrophysiological findings. 2. A comparison of hyperthyroidism with myasthenia showed that similarities and differences exist in the electrophysiological findings between both groups. 3. An additional, besides disturbances of neuromuscular transmission, factor determining muscular fatigibility in hyperthyroidism is probably damage to the muscle fibre.

[Subacute sensory neuronopathy with signs of involvement of anterior horn cells in a patient with small cell lung carcinoma (case report)]. / Podostra neuronopatia czuciowa z objawami uszkodzenia komórek ruchowych rogów przednich w raku drobnokomórkowym pluc (z opisem przypadku).

A 55 years old woman with small-cell lung carcinoma is described. Ten months after the diagnosis was established, subacute sensory neuronopathy with the signs of involvement of anterior horn cells (confirmed by EMG exam) occurred. Since neurological symptoms appeared at the time when anti-cancer treatment was ceased, the diagnosis of paraneoplastic lesion peripheral nervous system was established. Biopsy of sural nerve obtained 3 months after the onset of neurological signs showed nearly complete loss of normal looking myelinated fibers due to the process of axonal degeneration with relatively better preserved unmyelinated fibers. The patient died after 1 year and 2 months from the beginning of the disease because of metastatic tumours in the brain.

[Evaluation of remission in childhood myasthenia gravis]. / Ocena remisji w miastenii dzieciecej.

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.

[Hereditary motor-sensory neuropathy. II. Electrophysiological studies]. / Ruchowo-czuciowa neuropatia dziedziczna. Czesc II. Zmiany elektrofizjologiczne.

Electrophysiological parameters (conduction velocity, distal latency, amplitude of evoked response) were analysed in two types of sensorimotor hereditary neuropathy isolated on the ground of the values of motor conduction velocity in the median nerve which was 38 m/sec. Using this criterion the studied material of 53 cases could be divided into two groups. Group I of 34 cases in which the mean conduction velocity in the median nerve was 16.2 m/sec, and group II of 19 cases had a mean conduction velocity in the median nerve of 50.7 m/sec. The evaluation of the degree of slowing down of conduction in both types showed similar values in individual cases and in families.

[Atypical clinical image of myopathy with abnormal mitochondria (MAM) in our cases]. / Nietypowy obraz kliniczny miopatii mitochondrialnej (MAM) na podstawie przypadków wlasnych.

Two peculiar cases of mitochondrial myopathy are presented. In the first case the diagnostic difficulties are discussed stressing especially the differentiation of the myopathy from myasthenia. In the second cases polyneuropathy signs were evident, which is extremely rare in this myopathy.

[A case of progressive multifocal leucoencephalopathy during chronic lymphocytic leukaemia]. / Przypadek postepujacej wieloogniskowej leukoencefalopatii w przebiegu przewleklej bialaczki limfatycznej.

We report here a case of PML in the course of untreated chronic lymphocytic leukaemia. The diagnosis of PML was based on the presence of typical histologic findings in the white matter: focal demyelination, abnormal oligodendroglia with basophilic intranuclear inclusions and enlarged bizarre astrocytes. It was confirmed by immunohistochemistry which revealed JC papova-virus antigens in brain tissue and by in-situ hybridization which showed JC virus genomic DNA in oligodendroglial nuclei. Virus particles in the nuclei of abnormal oligodendrocytes and astrocytes were demonstrated by thin-section electron-microscopy.

[Neuropathies in small cell lung cancer]. / Neuropatie w raku drobnokomórkowym pluca.

A routine neurological examination, electromyography studies and conductance in sensory and motoric fibres of upper and lower extremity peripheral nerves, was carried out in 65 subjects with small cell lung cancer prior instituting chemotherapy. None of the patients demonstrated metabolic changes nor toxic injury to the neurological system. The results of the neurological examination led to suspicion of neuropathy in 22 (34%) which was later confirmed by the electromyographic studies. In 12 subjects only EMG abnormalities were found allowing to diagnose a subclinical phase of neuropathy. Altogether 52% of the subjects demonstrated injury of the peripheral nervous system. Sensory neuropathy was observed in 6 patients, motor-sensory in 7, motoric neuropathy in 12. In one of the subjects from the latter group a myasthenic syndrome of the Eaton-Lambert type was found. In 7 patients the EMG results suggested injury of the anterior horn cells, in two further patients the clinical and EMG data suggested injury of the peripheral and spinal column.