Actinic brachial plexus lesion

OBJECTIVES: To prove or disprove this assumption that in neuropathy patients with abundant spontaneous activity, peak-ratio interference pattern analysis may lead to false negative results. METHODS: Spontaneous activity >100 microV, automatically analysed by turn/amplitude analysis and expressed as (turns/second)/2 ((T/S)/2), and interference patterns, analysed by the peak-ratio technique, were recorded, one after the other, from the right anterior tibial muscle of 21 patients with neuropathy, aged 36-87 years. RESULTS: The mean number of spontaneous discharges ((T/S)/2) was 12.3 (range 5.5-26) and its mean amplitude 261 microV (range 146-478 microV). Despite this abundant spontaneous activity, peak-ratio analysis was neurogenic in 81% of the patients. All peak-ratio parameters were independent on the amount and amplitude of spontaneous discharges. CONCLUSIONS: Spontaneous discharges >100 microV could be adequately assessed by means of the turn/amplitude analysis and did not influence peak-ratio analysis in neuropathies.     

Diagnostic yield of analysis of the pattern of electrical activity and of individual motor unit potentials in myopathy

The analysis of the pattern of electrical activity and of individual motor unit potentials in the same muscle both identified about 90% of 41 patients as having a myopathy. The pattern of electrical activity was analysed during a force which was a fixed fraction of maximum; individual motor unit potentials were analysed during weak effort. The two methods supplement each other as some of the patients were identified only by one or by the other of the two procedures. The parameter of the pattern of electrical activity which was most often abnormal was the ratio: numbers of turns to mean amplitude between turns.     

Clonazepam in the treatment of panic disorder: a double-blind, placebo-controlled trial investigating the correlation between clonazepam concentrations in plasma and clinical response

The aim of this study was to investigate the possibility of neuromuscular dysfunction in patients with faecal incontinence by measuring interference patterns in the external anal sphincter and puborectalis muscles with quantitative electromyography. The design was an open study including 20 patients with faecal incontinence; in 14 the aetiology was idiopathic and 6 had rupture of the external anal sphincter. Electromyographic interference patterns (turns/amplitude analysis) measured at rest and during maximum voluntary contraction in all patients were recorded together with fibre density measured by single fibre electromyography (n = 10) and anal pressure measured at rest and at maximum contraction (n = 17). A comparison was made with results of a previously published series of reference values taken from normal volunteers. The density of the interference pattern on maximum contraction of the puborectalis muscle was significantly lower among the patients with idiopathic faecal incontinence than among the reference group (137 compared with 241 turns/second, p < 0.01). There was also a significant difference on maximum contraction of the anal sphincter muscle among the group in whom it was ruptured compared with the reference group (76 compared with 165 turns/second, p < 0.05). Fibre density increased with age and was significantly higher among those with idiopathic incontinence (1.64 (0.2) compared with 1.33 (0.1) in the reference group, p < 0.01). There were no significant differences in anal manometry measurements between the groups. In conclusion, in patients with faecal incontinence the role of central activation of the perineal muscles is important, though other factors may play a part.     

Identification, genomic organization, and alternative splicing of KNSL3, a novel human gene encoding a kinesin-like protein

Despite increasing importance of molecular genetics, electromyography has preserved its place as a valuable tool in the diagnostic procedure of myopathies. Conventional electromyography allows the assessment of spontaneous activity, motor unit action potentials and interference patterns. In myopathies, fibrillations and positive sharp waves can be found in the majority of the cases. Motor unit action potentials are of short duration, low amplitude and may show increased polyphasia and number of satellite potentials. The interference pattern may be of low amplitude and compact already at submaximal contraction. Compared to conventional electromyography, automatic interference pattern analysis provides quantitative results and has the higher sensitivity and specificity. Normal conventional or automatic electromyography does not exclude a myopathy. For diagnostic purposes, electromyography will be followed by muscle biopsy and DNA analysis in most of the cases.     

Electrophysiologic evaluation of denervated muscles in incomplete paraplegia using macro electromyography

OBJECTIVE: To evaluate denervated muscles in persons with incomplete paraplegia due to thoracolumbar spinal injury (TLSI) using macro electromyography in determining indications for functional electrical stimulation (FES). DESIGN: A randomized clinical trial and a criterion standard. SETTING: A department of orthopedic surgery in a university hospital. PATIENTS AND OTHER PARTICIPANTS: Eighteen patients with incomplete paraplegia, including 11 with TSLI, and 50 healthy adults. INTERVENTION: Area and amplitude of macro motor unit potential (macro MUP) were measured at the tibialis anterior, the vastus lateralis, and the vastus medialis. The normal limits of macro MUP parameters were defined based on values from healthy subjects. Abnormal denervated muscles were detected by macro EMG and conventional EMG in paralytic patients. The correlation between macro MUP parameter values and muscle forces of the tibialis anterior and quadriceps femoris induced by electrical stimulation was analyzed. MAIN OUTCOME MEASURES: The number of abnormal muscles, parameter values, and muscle force induced by electrical stimulation. RESULTS: Abnormal muscles were found only in the TLSI patients and 13 abnormal muscles were detected by macro EMG only. The abnormal muscles defined by macro EMG showed insufficient contraction induced by electrical stimulation. The increase of parameter value negatively correlated with the muscle force (tibialis anterior area r=-.797, amplitude r=-.866; quadriceps area r=-.866, amplitude r=-.893; p < .001). CONCLUSIONS: These results suggest that macro EMG is useful in detecting denervated muscles, in determining indications for FES, and in predicting FES effects before implantation of electrodes.     

Inclusion body myositis: clinical and pathological boundaries

Inclusion body myositis, polymyositis, and dermatomyositis are three distinct categories of inflammatory myopathy. Some authorities commented on the selective early weakness of the volar forearm muscles, quadriceps, and ankle dorsiflexors in inclusion body myositis. The most important feature distinguishing inclusion body myositis from the other two inflammatory myopathies is the lack of responsiveness to immunosuppressive treatment. Although most patients with inclusion body myositis have characteristic muscle biopsy findings, some cannot be distinguished histologically early from polymyositis. Predicting responsiveness to immunosuppressive medications, independent of muscle histology, would be valuable to clinicians. We retrospectively reviewed the pattern of weakness and other clinical features of 46 patients newly diagnosed with either inclusion body myositis, polymyositis, or dermatomyositis. Asymmetrical muscle weakness with prominent wrist flexor, finger flexor, and knee extensor involvement was specific for inclusion body myositis and unresponsive polymyositis. Male sex, lower creatine kinase levels, slower rate of progression, and peripheral neuropathy were also more common in inclusion body myositis and unresponsive polymyositis than in responsive polymyositis and dermatomyositis patients. Repeat muscle biopsy in 2 patients in the unresponsive polymyositis group demonstrated histological features of inclusion body myositis. We suspect that patients with clinical features of inclusion body myositis but lacking histological confirmation may nonetheless have inclusion body myositis. Our study supports the recently proposed criteria for definite and possible inclusion body myositis.     

Peripheral nervous system involvement in human and experimental chronic American trypanosomiasis

An electrophysiological and histological study of the muscle and the peripheral nervous system (PNS) was carried out in chronic human American trypanosomiasis (Chagas' disease) and in an experimental Chagas' disease (Chd) mouse model. Altogether 995 patients with chronic Chd and 261 mice, experimentally infected with RA and CA-I parasite strains, were investigated. Results were compared with matched controls. Techniques employed in humans were: clinical assessment, conventional electromyography (EMG), estimated number of motor units, motor and sensory nerve conduction velocities, repetitive nerve stimulation and muscle and sural nerve biopsies. In mice conventional EMG, sciatic nerve conduction time, sciatic nerve action potential amplitude, in vitro miniature end-plate potentials (MEPPs) and end-plate potentials (EPPs) recordings, muscle, nerve and spinal cord histology and identification of cell phenotypes within the inflammatory infiltrates were the employed procedures. Out of 511 patients submitted to clinical examination, 52 disclosed signs and symptoms of mixed peripheral neuropathy. By employing electrophysiological techniques, it could be shown that about 30% of the investigated patients had one or more of the following features: diminished interference pattern, most of the remainder motor unit potentials being (MUPs) polyphasic; reduced number of functional motor units in the thenar, hypothenar, soleus and/or edb muscles; slow sensory and motor nerve conduction velocities; low sensory action potential amplitude and impairement of neuromuscular transmission. In mice, MUPs duration and amplitude were increased at later stages of the infection, nerve conduction was slow, nerve action potentials were of low amplitude, mepps were of low amplitude and double epps were frequently found. Muscle histology in humans with chronic Chd showed type I and type II grouping, atrophic angular fibers and targetoid muscle fibers. In mice perivascular mononuclear cells infiltrates, small round fibers, muscle fibers necrosis, atrophic angular fibers, type II muscle fibers grouping and grouped muscle fibers atrophy were found. Sural nerve samples showed segmental and paranodal demyelination and axonal loss. The same features were observed in mice nerves, also in this model mononuclear cells infiltrates at the nerve, dorsal root ganglia and meninges surrounding the spinal cord were observed. Muscle and nervous tissues infiltrates were mainly composed of T lymphocytes with predominance of CD8 or CD4 subsets according to the parasites strain employed for infecting the animals. These findings suggest that the skeletal muscle and the PNS may be involved in chronic American trypanosomiasis.     

Neuromuscular function in HIV infection: analysis of a placebo-controlled combination antiretroviral trial. AIDS Clinical Group 175/801 Study Team

OBJECTIVE: To determine the frequency of peripheral neuropathy and myopathy in HIV-infected subjects enrolled in a combination antiretroviral treatment trial. DESIGN AND METHODS: AIDS Clinical Trial Group (ACTG) protocol 175 was a multicenter, double-blind, placebo-controlled, clinical trial. A total of 2467 subjects were randomized to one of four single or combination regimens, containing zidovudine (ZDV), didanosine (ddl), zalcitabine (ddC), and their respective placebos. Site investigators reported peripheral neuropathy, and the diagnosis of distal symmetrical neuropathy (DSP) was established by the study authors. Myalgia, muscle weakness and creatine phosphokinase (CPK) were prospectively assessed in a subset of the antiretroviral-naive cohort (n = 1067). RESULTS: Of 222 site diagnoses of neuropathy, 109 (49%) were DSP. There was a significant difference between treatment arms for rate of DSP and time to first grade 2 or higher DSP (ZDV-ddC, 6%; ZDV, 4%; ZDV-ddl, 4%; ddl, 3%; P = 0.029). Age and Karnofsky score were significant predictors of DSP. Fifty-six (54%) out of 104 patients with DSP remained on study medication at full (n = 29) or reduced (n = 27) dose within 6 months of developing neuropathy. There was no significant difference between treatment arms in the rate of myalgia or muscle weakness. The median CPK of subjects on ZDV-ddC was significantly higher than other study treatments, although CPK levels did not correlate with symptoms of myopathy. Only six subjects were diagnosed with myopathy during the study (one ZDV-ddl, one ZDV-ddC, and four ddl). CONCLUSIONS: DSP and myopathy may occur with current dosing regimens of combination antiretroviral therapy, and should be diagnosed using stringent criteria. ZDV-ddC was associated with the highest rate of DSP, although features of myopathy were not significantly different between treatment regimens.     

Superficial angiomyxoma of the right inguinal region: report of a case

Electromyography (EMG) is the most common procedure for screening patients with myopathies and remains the most important technique for assessing the course of the disease over time. Fibrillation potentials, positive sharp waves, myotonic or complex repetitive discharge, as well as polyphasic potentials are non specific and can occur in both myopathic and neurogenic lesions. The most sensitive and specific parameter for myopathy in conventional EMG is the decreased duration of motor unit potentials (MUP), but this can also be seen in disorders of the terminal motor fibers or the neuromuscular junction. More advanced techniques such as single fiber EMG, macro EMG, scanning EMG and turns/amplitude analysis have opened additional possibilities for analysis of the motor unit and the interference pattern, by which both the sensitivity to early changes and specificity for myopathic alterations is increased. The importance of combining different techniques to improve diagnostic yield and specificity is stressed.     

Self-reinnervated cat medial gastrocnemius muscles. II. analysis of the mechanisms and significance of fiber type grouping in reinnervated muscles

1. The technique of glycogen depletion was used to determine whether regenerating motor axons reestablish the normal regionalization of motor units (MUs) in the cat medial gastrocnemius (MG) muscle, 2) whether the extent of clumping between MU fibers and/or type grouping of muscle fibers progressively increases with a decrease in reinnervated MU numbers, and 3) whether the pattern of innervation can explain why MUs fail to increase significantly in size when the cut nerve is sutured directly to the muscle, even when few axons make functional connections. 2. Distributions of MU fibers were analyzed in 5 normal and 14 reinnervated cat MG muscles 4.5-16 mo after sectioning of its nerve and suturing of the proximal end to the distal nerve sheaths (N-N suture) or directly to the muscle fascia (N-M suture). Muscle unit distributions were quantified according to location, territory size, density, and extent of clumping between fibers from the same MU. 3. Normal MU fibers were regionalized within five regions along the muscle's longitudinal and transverse axes. Reinnervated MUs were located within similar regions, indicating that regenerating axons follow the major proximal nerve branches to restore normal compartmentalization. 4. Muscle unit fibers were diffusely scattered within discrete MU territories in normal muscles. Territory size tended to increase with MU size, whereas density of muscle unit fibers within the territory decreased. 5. Territories increased with MU size after N-N suture but were smaller and showed little size variation after N-M suture. The extent of muscle unit fiber clumping was inversely related to the number of reinnervated MUs. On average, the extent of clumping was substantially higher in muscles reinnervated after N-M suture. These results indicate that distal nerve sheaths facilitate proximal axon branching, which establishes MU territory size. Once the territory is established, motor axons branch distally to increase MU size, which in turn compensates for reduced MU numbers. 6. Muscles reinnervated by < 80% of the MUs exhibited fiber type grouping of type I fibers, and on average the extent of clumping was substantially higher in muscles reinnervated after N-M suture. With less innervation, type grouping increased inversely with the number of reinnervated MUs. However, for a similar number of MUs, type I fiber type grouping was substantially higher in muscle reinnervated after N-M suture. Type grouping therefore reflects muscle unit fiber clumping under conditions where MU size increased (N-N suture) or MU territory size decreased (N-M suture).     

Creatine phosphokinase-linked immunoglobulin associated with hypokalemic myopathy

We present three women with hypokalemic myopathy in whom serum creatine phosphokinase (CPK) was bound to serum immunoglobulin (macro-CPK). In all three cases, CPK isozyme electrophoresis demonstrated an extra CPK band between CPK-MM and CPK-MB. The bound immunoglobulins were identified as IgA/A-kappa and lambda, IgA-lambda and IgA-kappa and lambda, respectively. In all cases, histological examination of the biopsied muscles revealed necrotic and/or regenerating fibers. In each patient, potassium replacement therapy returned the macro-CPK as well as the marked elevations of serum muscle enzymes to normal. Taken together with other recent reports, our findings suggested that CPK-immunoglobulin binding may be related to the emergence of pathophysiology of hypokalemic myopathy.     

A family of autosomal dominant facio-limb-girdle muscular dystrophy

A family of autosomal dominant facio-limb-girdle muscular dystrophy was reported. The proband was a 28-year-old male. His father and sister suffered from a similar disease. All patients developed weakness of lower limbs and atrophy of thigh at second to fourth decades. All showed mild facial and neck flexor weakness as well as proximal dominant weakness and atrophy of four limbs. Limb muscle involvement was more severe in lower limbs than in upper limbs in all cases. Interestingly, all showed limitation of ankle dorsiflexion (tight heel cord), although distal muscles of lower limbs were not involved or only mildly involved clinically. On laboratory examination, serum CK increased slightly. Needle EMG revealed low amplitude, polyphasic MUP in limb muscles in all cases. Biopsied muscles taken from the proband showed non-specific myogenic changes. Rimmed vacuoles were not observed. Our cases were different from Bethlem myopathy, because the age of onset was late and joint contractures were mild in our cases, as compared with Bethlem myopathy. Clinical manifestations of our family showed a strong resemblance to the family reported by Girchlist et al, but similar cases were not reported in Japan.     

A continuous and pulsatile flow circulation system for evaluation of cardiovascular devices

In a previous report we suggested that muscle fibers in distal myopathy with rimmed vacuoles (DMRV) were degraded by both lysosomal proteolysis (cathepsins) and Ca2+-dependent, nonlysosomal proteolysis (calpain). Given recent evidence of abnormal ubiquitin accumulation in rimmed vacuoles, we examined the role of the ATP-ubiquitin-dependent proteolytic pathway (proteasomes) in myofiber degradation in this myopathy. Immunohistochemically, proteasomes (26S) were located in the cytoplasm in normal human muscle, but the staining intensity was weak. Quantitative analysis showed more reactivity for proteasomes in DMRV muscles and, to a lesser extent, in muscles from muscular dystrophy, polymyositis, and amyotrophic lateral sclerosis patients. In DMRV, proteasomes often were located within or on the rim of rimmed vacuoles, and in the cytoplasm of atrophic fibers. Ubiquitin accumulation was marked within rimmed vacuoles and was seen less extensively in the cytoplasm of atrophic fibers. The latter proteins colocalized well. In other diseased muscles, proteasomes and ubiquitin showed a positive reaction in the atrophic or necrotic fibers. The results indicate increased proteasome and ubiquitin in these muscle fibers as well as in other diseased muscle fibers. We suggest that the ATP-ubiquitin-proteasome proteolytic pathway as well as the nonlysosomal calpain and the lysosomal proteolytic pathway may participate in the muscle fiber degradation in DMRV.     

Absence of peripheral neuropathy in long-term lead-exposed subjects

The safety of a blood lead concentration of 70 microgram/100 ml as a hygienic border value with regard to development of lead neuropathy was tested in 95 employees, who had been exposed occupationally to lead for more than 9 years. The blood lead concentration was slightly above the border value in nine subjects, while the erythrocyte-Zn-protoporphyrin concentration was significantly elevated in 81 subjects, indicating an abnormal accumulation of metabolically active lead. None of the group showed clinical evidence of peripheral neuropathy, and the vibratory perception thresholds as well as motor conduction data from the median, radial, and common peroneal nerves were normal, as compared with an age-matched control group of 21 non-exposed normal subjects. The amplitude ratio between proximally and distally evoked muscle action potentials was normal in all lead-exposed subjects. These findings suggest that lead-exposed subjects are well protected against peripheral lead neuropathy, when blood lead levels are kept below the hygienic border value.     

Electromyography in nutritional osteomalacic myopathy

Electromyographic studies in 15 women with nutritional osteomalacia and proximal muscle weakness showed brief duration motor unit action potentials of normal amplitude and increased proportion of polyphasic motor unit potentials in the majority of them. By employing quantitative methods of electromyography, more positive results were obtained, thus reducing the sampling data. The histology showed non-specific muscle fibre atrophy without degenerative changes and the clinical and electromyographic examinations together showed clear evidence of a myopathy, suggesting a reversible transient block of the muscle fibres. Contrary to a recent suggestion, the nature of muscular change in osteomalacia remains the same regardless of its cause being nutritional or otherwise.     

Corticomotoneuronal contribution to the fractionation of muscle activity during precision grip in the monkey

1. During independent finger movements, the intrinsic muscles of the hand show a fractionated pattern of activity in which the timing and amplitude of electromyographic (EMG) activity varies considerably from one muscle to another. It has been suggested that, in the macaque monkey, corticomotoneuronal (CM) cells that produce postspike facilitation (PSF) of EMG in these muscles contribute to this fractionation. To test this hypothesis, we have investigated the relationship between the pattern of PSF exerted by a CM cell and the pattern of activity shown by the cell and by its target muscles. 2. The activity of 15 identified CM cells was recorded from two monkeys that performed a precision grip task. Spike-triggered averaging of rectified EMG during the hold period of this task showed that each cell produced PSF in at least two intrinsic hand muscles. 3. Segments of data were selected from the initial movement period of the task in which the EMG activity in one target muscle was substantially greater than that of the other, and the mean firing rate of each CM cell was determined for these periods. 4. CM cells showed bursts of activity in the movement period. Most of them (13/15) had a significantly (P < 0.001) higher firing rate when one of its target muscles was more active than the other. For nine of these cells (identified as set A), this muscle was the one receiving the larger PSF. In four cases (set B), the reverse was true. Two cells (set C), which produced PSF of equal size in their target muscles, showed no change in firing rate across the periods of fractionated EMG activity. 5. All set A and set B cells fired at significantly (P < 0.001) higher rates during the movement period, in association with fractionation of EMG activity, than in the hold period, in which a cocontracted pattern of muscle activity was observed. 6. There were pronounced differences in the strength of PSF exerted by the CM cells on their target muscles during the fractionation periods. One CM cell exerted PSF of a muscle during one period of fractionation, but postspike suppression of the same muscle during the other period. 7. It is suggested that changes in the firing rate of a CM cell and in the degree of facilitation it exerts could both contribute to the fractionation of activity in its target muscles. Cells of set A appear to be specifically recruited in a manner that directly reflects the pattern of facilitation they exert on the sampled target muscles. These results may explain why the CM system is so important for the performance of relatively independent finger movements.     

Cytoplasmic inclusion bodies: a study in several diseases and a review of the literature

Among 1400 muscle biopsies, we studied 16 cases with rimmed vacuoles, whose histology suggests cytoplasm inclusion bodies. We tried to correlate the clinical, laboratory and histopatological data in order to verify the specificity of cytoplasm inclusion bodies to certain diseases. The creatinekinase was increased in 10 cases. In all cases electromyography was abnormal. Muscle histochemistry revealed myopathy in 5 cases, mixed pattern in 7, denervation in 2 and in 2 cases, inflammatory myopathy. Electron microscopy showed the presence of filaments in 8 cases (nuclear, disseminated in cytoplasm or in the subsarcolemmal region). The patients were classified according to history, heredity, laboratory, electrophysiologic, histochemistry data and electron microscopy: in myositis with inclusion cytoplasmic bodies (4 cases), juvenile spinal muscular atrophy (6 cases), distal myopathies (3 cases), limb-girdle dystrophy (2 cases) and peripheral neuropathy (1 case). We present a revision on the pathogenesis and possible etiology of rimmed vacuoles and their relationship with several diseases.     

Acute corticosteroid myopathy in intensive care patients

Several recent studies have attributed the occurrence of acute myopathy in intensive care unit patients to the combination of corticosteroids and neuromuscular junction blocking agents (NMBAs) used for mechanical ventilation. We present 4 patients who developed acute myopathy after administration of high doses of glucocorticoids during sedation with propofol without any NMBAs. All patients had elevated creatine kinase levels. Electrophysiological studies indicated normal motor and sensory nerve conduction velocities but reduced motor nerve response amplitudes. Needle electromyography identified abnormal spontaneous activity; motor unit potentials were polyphasic of low amplitude and short duration, characteristic of a myopathic process. Muscle biopsy demonstrated a prominent acute necrotizing myopathy in all 4 patients with a loss of thick filaments. Our observations support glucocorticoids rather than NMBAs as the main offending drug in acute corticosteroid myopathy. The predisposing factor should be the hypersensitivity of paralyzed muscles to corticosteroids regardless of the drug inducing paralysis: NMBAs or propofol.     

A comparison of electroneuronography with facial nerve latency testing for prognostic accuracy in patients with Bell's palsy

The purpose of this study was to evaluate the ability of electroneuronography (ENOG), also called evoked electromyography (EEMG), and facial nerve latency testing (FNLT) to assess the prognosis of facial nerve palsy, using the House-Brackmann facial nerve grading system as criterion. From 1988 to 1994 these tests were employed at the ORL Clinic of the University of Ioannina in 250 patients with idiopathic facial nerve palsy. The ENOG test results indicated that when the amplitude of the compound muscle action potentials ranged from 51% to 95% of the normal value, 97% of the patients achieved complete functional recovery (grade I) within at least 2 months. When the muscle action potential decreased to a value below 51% of normal values, prognosis for recovery was considerably worse. FNLT test results indicated that as the latency time extended, the recovery grade of the facial nerve worsened. When latency time was within the normal range (group A patients), about 92% of patients had complete functional recovery. In contrast all patients having either a very extended latency time or unable to be monitored (groups C and D) demonstrated incomplete functional recoveries that ranged from grade II to grade VI. Comparing each test with the House-Brackmann facial nerve grading system, we ascertained that the percent accuracy for ENOG was 97.6%, and that for FNLT was 94.4%.