Atypical motor unit potentials in Emery-Dreifuss muscular dystrophy (EDMD).

OBJECTIVE: The aim of the study was to analyse electromyographic changes in Emery-Dreifuss muscular dystrophy (EDMD) that are atypical for myopathy. Our special interest was focused on high amplitude polyphasic motor unit potentials (MUPs), also termed irregular MUPs. METHODS: We studied 21 EDMD patients with the diagnosis based on clinical data, DNA analysis and immunohistochemical muscle studies. Rectus femoris muscle biopsies were investigated in all affected patients. Electrophysiological investigations involved quantitative concentric needle electromyography (CNEMG) of biceps brachii (BB) and rectus femoris (RF) muscles. Simulation studies were performed to approximate the number, diameter and distribution of muscle fibers, which contribute to irregular MUPs. RESULTS: The EMG data in EDMD were compatible with myopathy. Irregular MUPs showed longer duration, larger area, size index and higher amplitude then simple ones (P < 0.05). The approximation of features of muscle fibers contributing to irregular MUP also indicated smaller (<45 microm) and larger (>55 microm) diameters than normal (50 +/- 5 microm). Muscle biopsy specimens revealed the variable muscle fiber size due to atrophy, hypertrophy, and muscle fiber splitting. CONCLUSIONS: Irregular MUPs recorded in EDMD are due to hypertrophied and atrophied fibers as well as increased fiber density. They reflect reorganization of the motor unit in a slow progression myopathic process (muscle fiber hypertrophy and splitting). SIGNIFICANCE: Irregular MUPs in EDMD most probably reflect increased variability of the muscle fiber size.

The reorganisation of motor units in different motor neuron disorders.

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.

Diagnostic value of satellite potentials in clinical EMG.

Complex motor unit potentials (CMUPs) with satellites were recorded and analysed in 231 electromyograms of patients with spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), Duchenne muscular dystrophy (DMD) and a healthy control group. In the control adult group only few CMUPs with satellites were found; no CMUP were found in children. In SMA and DMD patients the CMUPs were present with similar frequency but their morphology, i.e. shape, duration, amplitude of the main and satellite spike components and number of satellites was different. In ALS patients a significant difference between severely involved interosseous muscle and proximal muscles was found. The pathomechanism of CMUPs with satellites is different in myopathic and neurogenic processes, in both however they reflect remodelling of the motor unit. In myopathy they reflect muscle fiber diameter variability and distribution of preserved muscle fibers within the motor unit under study. In neurogenic lesion the CMUPs with satellites are the result of increasing desynchronisation during progressive de- and reinnervation.

Motor unit changes in inflammatory myopathy and progressive muscular dystrophy.

The aim of present study was to analyse the motor unit (MU) changes in progressive muscle dystrophy (PMD) and in inflammatory myopathy (IM) and to evaluate eventual neurogenic factors in MU reorganisation. The material consisted of 20 patients with (PMD), 20 patients with (IM) and 20 healthy age-matched volunteers. The shape of concentric needle motor unit potentials (cn MUPs), including their duration, amplitude, area, size index and number of phases, the interference pattern and the amplitude and area of macro MUPs were evaluated. The cn emg data satisfied the classical criteria for myopathy in all examined patients, at least in one of the tested muscles. A decreased amplitude and/or area of macro MUPs, compatible with myopathy, were observed in 32 of the 40 patients. In some cases of chronic IM and PDM the long duration polyphasic potentials were recorded. The size index (SI) value of long polyphasic MUPs was usually decreased or normal. This feature indicated that desynchronisation of "myopathic" MUPs results from a reduced number of muscle fibers and their degeneration and regeneration. The results indicated no difference in MU reorganization between PMD and IM and no evidence of neurogenic factors in MU changes.

[Double discharges of motor unit -- importance in electromyographic diagnosis]. / Podwójne wyladowania jednostki ruchowej--znaczenie w diagnostyce elektromiograficznej.

The prevalence of double-discharge motor unit potentials (DD) in patients with neuromuscular disorders was analysed. Concentric needle electromyography was performed in 29 cases of spinal muscular atrophy (SMA), 25 cases of amyotrophic lateral sclerosis (ALS), 30 cases of Duchenne muscular dystrophy (DMD) and in 20 healthy controls. The DD were recorded only in the patients with neurogenic lesion, mainly in the ALS group. The diagnostic yield of DD in early detection of neurogenic lesion is discussed.

[Extrapyramidal signs in Alzheimer's disease]. / Zespól parkinsonowski w przebiegu choroby Alzheimera.

Extrapyramidal signs were assessed in 112 patients satisfying NINCDS/ADRDA criteria for probable Alzheimer's disease. They were present in 50% of the patients. The most common features of them were bradykinesia and rigidity. Resting tremor was rarely encountered. There were no significant differences in age of onset, symptom duration, presence of primitive reflexes and psychotic symptoms between cases with and without extrapyramidal signs, while the presence of extrapyramidal signs was associated with statistically significant greater dementia severity.

[Satellite potentials in electromyograms in patients with Duchenne progressive muscular atrophy]. / Wystepowanie potencjalów satelitarnych w elektromiogramach chorych z dystrofia miesniowa postepujaca typu Duchenne'a.

CN EMG study was performed in 30 patients with Duchenne Muscle Dystrophy. The frequency of Motor Unit Potential (MUP) with satellite components was reviewed. The amplitude and duration of individual components as well as the distance between main MUAP and satellite components were measured. The results were correlated with clinical data (duration of the disease, muscle force and wasting) and morphological (obtained from rectus femoris open biopsy). Satellite components were found in 34% of the MUP number. A positive correlation was found (p 0.001) between the duration of the complex MUP (main MUP with satellite components) and muscle force. There was no evident correlation between the morphological findings (muscle fibre regeneration and necrosis) and occurrence of satellite potentials. The diagnostic yield of satellite potentials in neuromuscular diseases in discussed.

[Median nerve electrophysiological assessment in amyotrophic lateral sclerosis]. / Ocena elektrofizjologiczna nerwu obwodowego w stwardnieniu zanikowym bocznym.

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.

[Diagnostic yield of electrophysiological and immunological studies in inflammatory myopathies]. / Zastosowanie badan elektrofizjologicznych i immunologicznych do diagnostyki miopatii w chorobach tkanki lacznej.

The aim of the study was to estimate the value of the immune markers in defining distinct subsets of inflammatory myopathies. The series of 76 patients was divided, on the basis of the clinical data, into 5 groups (polymyositis (PM), dermatomyositis (DM), scleromyositis (Scm), mixed connective tissue disease (MCTD), unclassified). In all cases detailed clinical, electrophysiological (concentric needle electromyography (CNEMG) and skin sympathetic response (SSR)) were performed as well as immunologic studies: the anti Mi-2, anti RNP, PM-Scl, Jo-1. The findings indicate that immune markers have a diagnostic value in differentiating the defined subsets of patients different in respect of course, prognosis and therapeutic indications. The authors stressed the value of the Jo-1 antibody in detecting the subset of polymyositis with coexisting interstitial lung disease. Electrophysiological data do not differentiate the groups of patients with different clinical syndrome and different immune markers. EMG results seem however to be useful in monitoring the course of the disease and response to the therapy.

Electromyographic findings in different forms of infantile and juvenile proximal spinal muscular atrophy.

Quantitative electromyography (EMG) was performed in 223 infantile and juvenile cases of spinal muscular atrophy (SMA), which were classified into 3 groups: (A) form Ia, Werdnig-Hoffmann disease; (B) forms Ib and II, intermediate forms; and (C) form III, Kugelberg-Welander disease. The groups differed in the occurrence of spontaneous activity; only groups A and B showed spontaneous rhythmic firing of motor units, whereas in long-standing cases, pseudomyotonic volleys appeared. The parameters of individual motor unit potentials (MUPs) differed in the different forms of the disease. Group A showed, in addition to long potentials of high amplitude, some short and low amplitude potentials, and the histograms of amplitudes and durations were bimodal. In the long-standing cases, the values of these parameters were shifted to longer durations and higher amplitudes of motor unit potentials. However, in long-standing cases of the benign group C, the short, low potentials appeared as well as so-called linked potentials. In the very early stage of the disease, the children who were found to be suffering from chronic forms of SMA--both malignant (form Ib and II or benign group C)--had an EMG record that was slightly different from that of acute form Ia. Their EMG record shows more so-called "spinal" signs, particularly in the benign group C (Kugelberg-Welander disease). These increasing features of chronic anterior horn cell involvement followed a pattern of reinnervation and hypertrophy of muscle fibers. These phenomena were particularly seen in the benign group C. These findings indicate that in the early stage of SMA, the EMG not only has diagnostic, but also prognostic, value.

The reorganization of motor units in motor neuron disease.

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.

Motor unit hyperexcitability in amyotrophic lateral sclerosis vs amino acids acting as neurotransmitters.

OBJECTIVES: Electrophysiological studies of amyotrophic lateral sclerosis (ALS) patients reveal not only lower motor neuron involvement, but also widespread signs of its hyperexcitability. They might be the consequence of changes in the level of amino acids acting as neurotransmitters. MATERIAL AND METHODS: Electrophysiological examination of 31 patients with sporadic ALS was performed. A hyperexcitability index (HI) was created to describe the amount of double discharges, fasciculation potentials or 'giant' F-waves. Glutamate, aspartate, glycine and GABA concentration in serum and cerebrospinal fluid (CSF) were estimated, using the high performance liquid chromatography technique. RESULTS: The electrophysiological studies revealed marked variability in HI in the patients group. HI did not correlate with duration of the disease and the degree of disability expressed with Norris score, as well as with the level of excitatory or inhibitory amino acids in the body fluids. CONCLUSION: Hyperexcitability of the motor unit observed in ALS is not directly related to changes in serum and CSF level of amino acids acting as neurotransmitters.

Analysis of creatine kinase activity in 504 patients with proximal spinal muscular atrophy types I-III from the point of view of progression and severity.

Mild to moderately elevated creatine kinase (CK) activity is a frequent biochemical finding in proximal spinal muscular atrophy (SMA). In a collaborative study on all types of childhood and juvenile onset SMA, we analysed the CK activity of 504 SMA patients (138 type I, 127 type II, 144 type IIIa, and 95 type IIIb patients). Under the assumption of a lognormal distribution of CK activity as the most appropriate statistical model, CK levels were transformed into logarithms and compared by standard deviation scores = CK-SDS (log). CK activity was statistically different between early and later onset SMA: in SMA I and II, about one-third of patients showed CK-SDS (log) >2 SD, the analysis of the means did not show significant differences. In SMA III, CK-SDS (log) was significantly higher (p < 0.01) than in the two other groups, which was most pronounced in SMA IIIb. More than 90% of SMA IIIb patients showed CK-SDS (log) values >2 vs. 57% in SMA IIIa. As similar values were obtained for a subgroup of 100 patients in whom the diagnosis of autosomal recessive SMA was confirmed by a deletion of the telomeric copy of the survival motor neuron gene, our results can be considered representative for SMA I-III. There was no correlation between CK level and disease duration. The fact that patients were ambulatory or chair-bound had no influence on CK activity in type III SMA. There was no sex influence in SMA I, II and IIIa. The observed higher male values in the group SMA IIIb are most likely the result of a lack of female patients with onset after puberty.