Pattern of involvement in the cervical segments in the early stage of motor neurone disease: A single fibre EMG study

The right and left biceps and first dorsal interosseous muscles of 22 patients with motor neurone disease were studied by single fibre EMG at the time of diagnosis. The mean duration of symptoms was 8.1 months. The fibre density was increased in 87 of the 88 muscles studied. In the first dorsal interosseous muscles the fibre density was increased similarly on both sides, but in the biceps muscles of normal strength the fibre density was more markedly increased on the left than on the right. These findings suggest that in the early stage of the disease certain motor unit pools in the spinal cord are preferentially affected.     

The reinnervated motor unit in man. A single fibre EMG multielectrode investigation.

Motor units in patients with motor neurone disease and polyneuropathy were studied with a new multielectrode technique allowing fibre mapping. In these disorders which are characterised by reinnervation the motor unit fibre distribution is changed from a normal scattered pattern to grouping often in clinically uninvolved muscles without definite EMG abnormalities. The changes found with this multielectrode technique in man are in accordance with those found in reinnervated motor units studied histochemically in the experimental animal.     

副肿瘤综合征电生理及病理学研究(附一例报告)

目的探讨以运动神经元病为表现的副肿瘤综合征的临床、电生理学、病理学特点。方法对1例肠癌肺转移患者的临床表现、肌电图神经重复刺激检查、肌肉组织化学进行研究。结果该例患者表现为进行性肌肉力弱,肌电图显示神经源性损害,神经重复刺激检查示波幅下降,肌肉病理显示小簇状肌肉萎缩,电镜下除极少数肌纤维膜溶解外其他未见特殊。结论肠癌合并副肿瘤综合征可表现为运动神经元病。     

Concentric-needle versus macro EMG. II. Detection of neuromuscular disorders.

OBJECTIVE: Little is known about the relation and sensitivity of macro-EMG (MA-EMG) compared with concentric-needle EMG (CN-EMG) in the detection of neuromuscular disorders. METHODS: CN-EMGs and MA-EMGs were recorded from the right brachial biceps muscle of 40 healthy subjects, aged 17-83 years, 20 patients with neurogenic disorders, aged 25-75 years, and 20 patients with myopathy, aged 18-76 years. Motor unit action potentials (MUAPs) were examined. RESULTS: In patients with neurogenic disorders CN-MUAP duration, CN-MUAP amplitude, percent polyphasia, MA-MUAP amplitude, MA-MUAP area and fibre density were significantly increased. In patients with myopathy, only fibre density was significantly increased. In patients with neurogenic disorders, the sensitivity of CN-EMG was 80%, and that of MA-EMG 85%. In myopathies, the sensitivity was 50% for each technique. Pooling the results of both EMG techniques, the sensitivity increased to 90% in patients with neurogenic disorders, and to 65% in myogenic disease. CONCLUSIONS: MA-EMG has a similar sensitivity in the detection of neuromuscular disorders as CN-EMG. Particularly when myopathy is suspected, both techniques should be applied if one is unrevealing.     

Comparison of electrophysiological and histochemical methods for assessing the spatial distribution of muscle fibres of a motor unit within muscle

The spatial distribution of muscle fibres of a motor unit has been examined in patients with a variety of neuromuscular disorders using the fibre density (FD) technique of single fibre EMG and the enclosed fibre count (EFC) method, and the results of the two approaches compared. Agreement between the findings occurred in 64% of cases; an increase in both parameters was seen only in neurogenic conditions. FD was found to be more sensitive to minor disturbances of motor unit architecture as seen in myopathies and mild neurogenic states, and this factor together with sampling differences accounted for most of the discrepancies between the two methods. The finding of normal FD and EFC values in the presence of fibre type disproportion helped to exclude reinnervation as the cause by confirming the predominantly diffuse distribution of muscle fibres.     

Pathogenesis of ano-rectal incontinence. A histometric study of the anal sphincter musculature.

Type 1 fibre predominance was found in the external anal sphincter, puborectalis and levator ani muscles of 17 control subjects, and of 16 patients with ano-rectal incontinence. In the external anal sphincter and puborectalis muscles of the control subjects the mean diameter of Type 2 fibres was slightly greater than that of Type 1 fibres, but in the levator ani muscles of control female subjects the mean diameter of Type 1 fibres was much greater than that of Type 2 fibres. In the patients with anorectal incontinence there was marked hypertrophy of fibres of both histochemical types. This was most marked in the puborectalis and external anal sphincter muscles. In 12 of the 16 incontinent patients there were histological and statistical features consistent with a neurogenic disorder. These histometric studies provide a quantitative basis for physiological and pathological studies of these muscles in incontinence and other anorectal disorders.     

Muscle velocity recovery cycles in neurogenic muscles

ObjectiveTo examine muscle membrane properties in neurogenic muscles using Muscle Velocity Recovery Cycles (MVRCs).MethodsForty-seven patients referred to Nerve Conduction Studies (NCS) and Electromyography (EMG) for peroneal nerve entrapment neuropathy were prospectively included. The patients were categorized as peroneal nerve entrapment neuropathy across knee (n = 22), L5-radiculapathy (n = 10), normal NCS/EMG (n = 9) and other disorders (n = 6) using NCS/EMG and neuroimaging results. Strength in anterior tibial muscle was measured by Medical Council Scale (MRC) and disease duration was recorded. In addition to conventional NCS/EMG, all subjects were examined with MVRCs in anterior tibial muscle. This provided parameters of muscle relative refractory period (MRRP) and early supernormality (ESN) and late supernormality (LSN). The results were compared with 29 age-matched healthy control subjects.ResultsMRRP was prolonged and ESN and LSN were reduced in neurogenic muscles. MRRP, ESN and LSN correlated to MRC and incidence of spontaneous activity but not to motor unit potential parameters or disease duration.ConclusionsMVRC changes provide in vivo evidence of depolarization in intact human muscle fibres that could underlie reduced muscle excitability and hence weakness in neurogenic muscles.SignificanceMVRCs appear to be a useful technique for revealing disease mechanism in a broad range of neuromuscular diseases.     

Chronic asymmetrical spinal muscular atrophy

The clinical and neurophysiological features of 18 cases of chronic asymmetrical spinal muscular atrophy are described. These were patients presenting with asymmetrical neurogenic atrophy involving one or more limbs who had no evidence of pyramidal tract dysfunction after 3 or more years of symptoms. There were twice as many males as females and the mean age of onset of the disorder was about 32 years. None of the patients had bulbar involvement. The tendon reflexes tended to be depressed. The distribution of muscle weakness in the limbs was very variable, and only slowly progressive. In 5 cases symptoms and signs were confined to the hands and forearms. Motor nerve conduction velocities to wasted muscles were slightly reduced but there was no evidence of generalised neuropathy. A diagnosis of chronic asymmetrical spinal muscular atrophy, as opposed to that of classical motor neurone disease, is favoured by an age of onset under 40 years, an absence of pyramidal signs or bulbar involvement after 3 years or more of symptoms, and depressed or absent tendon reflexes. The 2 conditions appear to be clinically distinct and prognosis is considerably better in chronic asymmetrical spinal muscular atrophy. The aetiology of this condition in unknown; it may be of relevance that 2 patients in this series had close relatives with Werdnig-Hoffmann disease.     

Longitudinal fibre splitting in neurogenic muscular disorders--its relation to the pathogenesis of "myopathic" change.

In 15 patients with neurogenic muscular disorders, including cases of motor neuron disease, Wohlfart-Kugelberg-Welander disease, Davidenkow's scapuloperoneal syndrome, peripheral neuropathy and traumatic neuropathies, muscle biopsies were carried out, usually after EMG or single fibre EMG investigation. Enzyme histochemical and electronmicroscopic techniques were used to study longitudinal fibre splitting and its quantitative relation to the general changes in the biopsies. In 9 cases serial sections were used to study the longitudinal extent and character of fibre splitting. Longitudinal fibre splitting was found in 14 cases. It was prominent in Type 1 fibres, and in those biopsies in which hypertrophy was most marked. It was often associated with central migration of sarcolemmal nuclei. Ultrastructurally there was evidence that splitting consisted of mechanical disruption of the myofibrillar pattern, followed by an active process of membrane formation. We suggest that longitudinal splitting of muscle fibres, induced by overload of poorly innervated, hypertrophied fibres, can account for many of the "myopathic" changes found in neurogenic muscular disorders.     

Comparison between concentric needle EMG and macro EMG in patients with a history of polio.

OBJECTIVES: Acute poliomyelitis causes degeneration of anterior horn cells, followed by denervation. Reinnervation and muscle fibre hypertrophy are mechanisms that compensate this loss of neurones. Concentric needle EMG (CNEMG) and macro EMG are two methods to assess the magnitude of initial involvement and the compensatory reinnervation. The aim of this study is to explore the difference between CNEMG and macro EMG describing the status of the motor unit in patients previously affected by polio. METHODS: Macro and concentric needle EMG investigations were performed in 261 muscles in 121 patients with a remote history of polio. RESULTS: CNEMG was abnormal in 211 muscles, macro EMG was abnormal in 246 muscles. The macro amplitude was 3-4 times 'more abnormal' than CNEMG amplitude relative to the reference values. CNEMG duration was less abnormal and showed only weak correlation with macro amplitudes. The most likely explanation for the difference in magnitude of deviation from reference values for CNEMG and macro EMG, is a more pronounced 'phase cancellation' between single fibre action potentials in CNEMG. This is supported by simulation studies reported here. CONCLUSIONS: In conclusion macro EMG better reflects the size of the motor unit than the CNEMG. For detection of concomitant disorders, CNEMG is the method of choice.     

Chronic neurogenic quadriceps amyotrophy

Two patients with chronic neurogenic quadriceps amyotrophy are reported. A 61-year-old woman had symmetrical wasting and weakness of the quadriceps femoris of eight years' duration. A biopsy revealed neuropathic changes, and electromyograms showed neurogenic as well as myopathic patterns in the quadriceps and other muscles. A 29-year-old woman had long-standing wasting limited to the quadriceps and hip muscles. EMG and biopsy were compatible with neurogenic atrophy. She had a brother suffering from a more widespread and severe form of the disease. These cases suggest that chronic neurogenic quadriceps amyotrophy is a forme fruste of Kugelberg-Welander disease.     

Open-biopsy electromyography. Direct correlation of a pattern of excessively recruited, pathologically small motor unit potentials with histologic evidence of neuropathy.

Open-biopsy electromyography (EMG) of two muscles of a 29-year-old man with slowly progressive proximal weakness demonstrated a striking pattern of excessively recruited, pathologically small motor unit potentials. This pattern is usually equated with myopathy. Histologic study of tissue enclosing the recording sites, however, yielded evidence of neurogenic disease alone. In muscle, this included isolated and small groups of atrophic type I, IIA, and IIB fibers, and in intramuscular nerve a loss of myelinated fibers with connective tissue and Schwann cell proliferation. The EMG pattern is considered to reflect a reduced number of activated muscle fibers within motor units due to random neurogenic involvement of terminal axons.     

Ballistic elbow flexion movements in patients with amyotrophic lateral sclerosis.

Patients with amyotrophic lateral sclerosis made stereotyped 20 degrees elbow flexion movements as rapidly as possible while surface EMG was recorded from biceps and triceps. The characteristic ballistic movement EMG pattern could be recognised in almost all the patients. The first agonist burst and the first antagonist burst, which are normally limited in duration, were prolonged in patients with clinical signs of pyramidal tract disease or alpha motor neurone disease or both. Prolongation of these components permits the muscles to generate sufficient forces to accomplish the movements.     

Fibre density,amplitudes of macro-EMG motor unit potentials and conventional EMG recordings from the anterior tibial muscle in patients with amyotrophic lateral sclerosis

Summary Fibre density and amplitudes of macro-EMG motor unit potentials were studied and compared with conventional EMG in the anterior tibial muscles from 51 patients with amyotrophic lateral sclerosis. The fibre density was increased in 46 muscles. Increased amplitudes of macro-EMG motor unit action potentials were found in 46 muscles, while the mean duration of motor unit potentials recorded with a concentric needle electrode was prolonged in only 26 muscles. Changes in the packing density of muscle fibres of surviving motor units are thought to influence the different electrophysiological parameters in different ways.     

Possible neurogenic factor in muscular dystrophy: its similarity to denervation atrophy

Muscle biopsy specimens from 179 cases of muscular dystrophies and from 140 cases of anterior horn cell disorders (from a total of 1,348 biopsied patients) were examined histologically. There were 72 cases of Duchenne type muscular dystrophy (DMD), five of Becker type MD, four girls with myopathy resembling DMD, 40 with limb-girdle, 10 with facioscapulohumeral, seven with late onset, 13 with congenital, and 28 with unclassifiable muscular dystrophies. Groups of small atrophied muscle fibres were encountered in 42 (23%) of the cases in this group, most frequently in patients with limb-girdle, facioscapulohumeral, and least frequently with DM dystrophy. In the second group there were 25 cases of infantile, 38 of juvenile, and 39 of adult spinal muscular atrophy (SMA); there were 21 patients with motor neurone disease (MND), six with poliomyelitis, and 11 with an unclassifiable type of anterior horn cell disorder. Pseudomyopathic changes were encountered in 43 (30%) of all cases in this group. They were most frequently present among patients with juvenile and adult SMA and in those with MND. The presence of group atrophy in muscular dystrophy is considered significant myopathological evidence of a denervation process. On the other hand, pseudomyopathic changes, variation in fibre size, rounding, central nuclei, and increase in connective tissue occurring in various anterior horn cell disorders are seen not to be specific `myopathic'' changes. Thus there was an overlap of pathological reactions in muscles from the dystrophies and the neurogenic atrophies. Comparably atrophied fibres (much less than 2 SDs below the normal mean diameter) and hypertrophied fibres (much more than 2 SDs above the normal mean diameter) were encountered in both dystrophy and neurogenic atrophy, considering the large muscles of the limb. Likewise, the mean fibre diameters were comparable in DMD and in juvenile SMA. The fourth evidence of a neurogenic factor in muscular dystrophy was derived from an examination of SDH preparations of muscle. There was a preponderance of type I muscle fibres in dystrophic muscles compared with specimens from controls, suggesting depletion of type II fibres. It appears that the concept of muscular dystrophy as a primary muscle disease needs to be re-examined.     

Unusual manifestations of herpes zoster. A clinical and electrophysiological study.

The literature on complicated herpes zoster is summarized in this paper. The case histories of 18 patients with herpes zoster are presented. Two patients had encephalitis, 2 had myelitis and the other 14 patients had various types of lower motor neurone disturbance. Both patients with encephalitis--one of who developed choreo-athetosis during the illness--recovered fully. Only 1 of the 2 patients with myelitis recovered fully; the other remains severely paraparetic and the reason for her incomplete recovery may be related to the presence of generalized arteriolar disease associated with seronegative rheumatoid disease. One patient developed a Guillain-Barre syndrome 3 weeks after the onset of herpes zoster. Recovery in the 15 patients with lower motor neurone involvement has been slow butcomplete--or almost complete--in all but 1, a patient with persistent facial weakness as part of the Ramsay Hunt syndrome and who also had weakness of one upper limb. Seven other patients had lower limb weakness. In 2 patients the weakness was confined to abdominal myotomes and 2 other patients had urinary retention. Electromyographic abnormalities were found in the muscles which were weak and frequently also in muscles which appeared strong. It is emphasized that neurological disturbances other than sensory abnormalities may be found in patients with herpes zoster. Motor complications of various types are not uncommon.     

EMG power spectrum, turns-amplitude analysis and motor unit potential duration in neuromuscular disorders

The diagnostic value of power spectrum analysis of the needle EMG pattern at a force of 30% of maximum was compared to that of turns-amplitude analysis and to that of manual measurements of motor unit potential (MUP) duration in the brachial biceps muscle of 20 patients with myopathy and 11 patients with neurogenic disorders. In myopathy the power spectrum analysis had the same diagnostic value as the turns-amplitude analysis and MUP duration measurements and the 3 methods supplemented each other. In patients with neurogenic disorders the diagnostic value of the power spectrum analysis as well as that of the turns-amplitude analysis were lesser than that of MUP duration measurement. In diseased muscles the amount of high frequencies increased with increasing ratio of turns to mean amplitude while there was no relation between the power spectrum and the MUP changes. The results suggest that the power spectrum analysis of EMG can be used as a diagnostic tool in patients with neuromuscular disorders.     

Time dependent selective recurrent discharge of motor units in F-response

The interaction among the recurrent discharge of motor units is studied in surface recorded composite F-response. In the first experiment, 200 serially elicited polyphasic F-responses from foot muscles of patients with different lower motor neurone (LMN) disorders were rearranged to understand the behaviour of individual negative and positive peaks. These peaks were considered on the basis of simultaneous recording with a single fibre EMG needle, to be the partial expression of either a single motor unit potential (MUP) or more than one MUP generated simultaneously. In another experiment, two serially averaged F-responses (50 each) were superimposed over each other to look for their similarities at 15 min intervals 6 times. Result analysis indicated interaction of MUPs by in-phase summation and out-of-phase subtraction. Less affected MUPs recurred as negative or positive peaks in morphologically different F-responses. Certain peaks were observed more frequently than the others. Two serially averaged F-responses were nearly identical on superimposition over each other but their morphologies differed at different time intervals. The study suggests more frequent generation of F-response in a specific group of alpha motoneurones at one point of time, which is replaced by another group at another point of time. The characteristic variation in F parameters is, however, mainly due to the interaction of these frequently generated F-response MUPs with other sporadically generated ones. This interaction can be appreciated on visual screening of F-responses in patients with lower motor neurone disorders, perhaps because of a reduction in the number of participating MUPs.     

Use of Bayesian MUNE to show differing rate of loss of motor units in subgroups of ALS

Objectives

To evaluate differences among patients with different clinical features of ALS, we used our Bayesian method of motor unit number estimation (MUNE).

Methods

We performed serial MUNE studies on 42 subjects who fulfilled the diagnostic criteria for ALS during the course of their illness. Subjects were classified into three subgroups according to whether they had typical ALS (with upper and lower motor neurone signs) or had predominantly upper motor neurone weakness with only minor LMN signs, or predominantly lower motor neurone weakness with only minor UMN signs. In all subjects we calculated the half life of MUs, defined as the expected time for the number of MUs to halve, in one or more of the abductor digiti minimi (ADM), abductor pollicis brevis (APB) and extensor digitorum brevis (EDB) muscles.

Results

The mean half life of MUs was less in subjects who had typical ALS with both upper and lower motor neurone signs than in those with predominantly upper motor neurone weakness or predominantly lower motor neurone weakness. In 18 subjects we analysed the estimated size of the MUs and demonstrated the appearance of large MUs in subjects with upper or lower motor neurone predominant weakness. We found that the appearance of large MUs was correlated with the half life of MUs.

Conclusions

Patients with different clinical features of ALS have different rates of loss and different sizes of MUs.

Significance

These findings could indicate differences in disease pathogenesis.     

Quantitative electromyography of the external anal sphincter in Parkinson's disease and multiple system atrophy

The distinction of multiple system atrophy (MSA) from Parkinson's disease (PD) can be difficult, especially early in the disease. In MSA degeneration of sacral anterior horn cells (Onuf's nucleus) results in denervation-reinnervation of anal and urethral sphincter muscles, which can be recognized as neurogenic electromyographic (EMG) changes of motor unit potentials. Sphincter EMG has therefore been recommended as a test for distinguishing MSA from PD. Our results confirm the presence of marked neurogenic EMG changes of the external anal sphincter muscle in patients with probable MSA compared to healthy controls. However, in patients with probable PD, our quantitative EMG data show a scatter from normal to marked neurogenic changes and the degree of EMG abnormality is correlated to the duration of the disease. Thus an abnormal sphincter EMG cannot be taken as a strong indicator of MSA rather than PD in the individual patient, especially in long-standing cases.