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Arthrogryposis multiplex congenita. I. Clinical and electromyographic aspects.

Sixteen cases with arthrogryposis multiplex congenita were examined clinically and electromyographically; three of them were re-examined later. Joint deformities were present in all extremities in 13 of the cases; in eight there was some degree of mental retardation. In two cases, there was clinical and electromyographic evidence of a myopathic disorder. In the majority, the appearances of the shoulder-neck region suggested a developmental defect. At the same time, selective weakness of muscles innervated by C5-C6 segments suggested a neuropathic disturbance. EMG revealed, in eight of 13 cases, clear evidence of denervation of muscles, but without any regenerative activity. The non-progressive nature of this disorder and capacity for improvement in muscle bulk and power suggest that denervation alone cannot explain the process. Re-examination of three patients after two to three years revealed persistence of the major deformities and muscle weakness noted earlier, with no appreciable deterioration.

Adolescent↗

Physiological abnormalities of skeletal muscle in dialysis patients.

BACKGROUND: Muscle weakness is a common but unexplained feature of dialysis patients. This study investigated the prevalence and causes of muscle weakness in dialysis patients by examining the quadriceps muscle force and contractile properties. METHODS: The quadriceps femoris was studied in terms of force, force-frequency curve, and speed of muscle relaxation in 49 dialysis patients and 27 healthy subjects. In addition nutritional, haematological, biochemical, and histological assessments were performed, and steps of force generation were analysed to reach the possible mechanisms leading to the observed weakness. RESULTS: Muscle weakness, though invariable as a symptom, was subtle or absent on clinical examination. Quadriceps force measurements, however, revealed unequivocal weakness in most of the patients (71%). The quadriceps muscle was weaker (317 +/- 115 versus 460 +/- 159 N, P < 0.01) compared to healthy individuals, but there was no evidence of impaired excitation-contraction coupling (0.79 +/- 0.05 versus 0.76 +/- 0.07, P = 0.1). Among dialysis patients the older and the malnourished (n = 23) were the weaker but there was no relationship to the type or duration of dialysis. The serum albumin was the only biochemical parameter related to the muscle force (r = 0.6, P = 0.01). The other most prominent abnormality of quadriceps muscle function observed in this study was slowing of relaxation (patients versus controls; 8.7 +/- 1.8% versus 10.8 +/- 1.1% force loss/10 ms, P < 0.0001) particularly in the malnourished group (malnourished versus well nourished; 8.3 +/- 2.1 versus 9.4 +/- 0.95, P = 0.03). Muscle histology was investigated (n = 12) and revealed that type II fibres were mildly atrophic in 40% of the biopsies in most areas, but predominantly type IIB. Although type IIB fibre areas are slightly smaller in the dialysis patients compared to the controls, this was not statistically significant (3025 +/- 578 versus 4406 +/- 1582, P = 0.1) except in the malnourished group compared to the well-nourished dialysis patients (2092 +/- 304 versus 4346 +/- 1496, P = 0.04), and in the malnourished dialysis patients type IIB fibre area was significantly correlated to the strength (r = 0.6, P = 0.02). CONCLUSIONS: The only significant predictor of loss of muscle strength and abnormality of relaxation in this study was the nutritional state. A regular assessment of the nutritional state is required to ensure adequate nutrition to prevent the observed abnormalities of the skeletal muscles.

Adult↗

Effect of parathyroidectomy on respiratory muscle strength in uremic myopathy.

We report the case of a uremic dialysis patient with severe secondary hyperparathyroidism, proximal muscle weakness and impaired respiratory muscle strength, the latter being assessed by maximal inspiratory pressure. After subtotal parathyroidectomy, we observed a marked improvement in respiratory muscle strength (27 vs. 87 cm H2O) and disappearance of proximal muscle weakness.

Adult↗

Sleep and breathing in neuromuscular disease.

Respiratory muscle weakness in neuromuscular disease causes significant morbidity and mortality. The published data on respiratory muscle activity and breathing during sleep in normal subjects, the impact of respiratory muscle weakness on sleep and breathing and the relations to daytime respiratory function in neuromuscular disease are reviewed here. In normal subjects during sleep upper airway resistance increases, chemosensitivity is reduced and the wakefulness drive to breathe is lost, resulting in a fall in ventilation. During rapid eye movement (REM) sleep, ribcage and accessory breathing muscles are suppressed, particularly during bursts of eye movements, and breathing is more irregular, rapid and shallow, with a further fall in ventilation. In subjects with respiratory muscle weakness sleep is fragmented, with shorter total sleep time, frequent arousals, an increase in stage 1 sleep and a reduction in, or complete suppression of, REM sleep. Sleep-disordered breathing and nocturnal desaturation are common and most severe during REM sleep. Correlations between daytime respiratory function and nocturnal desaturation are moderate or weak, but daytime respiratory function has greater prognostic value than nocturnal measurements. Noninvasive ventilation improves sleep quality and breathing in subjects with respiratory muscle weakness. However, the optimal criteria for initiation of ventilation and its role in rapidly progressive neuromuscular diseases are unclear.

Humans↗

[Familial amyotrophic lateral sclerosis with rapid progression].

We report a family with autosomal dominant (AD) motor neuron disease. A 41-year-old man developed muscle weakness and fasciculation of the lower extremities. The weakness progressed to the upper extremities and bulbar muscles. The cerebrospinal fluid (CSF) protein level was slightly elevated. A nerve conduction study revealed reduced compound muscle action potentials, but conduction block was not observed. Electromyogram showed acute and chronic neurogenic changes. He was treated with intravenous immunoglobulin (IVIg) and methylprednisolone pulse therapy, but his condition rapidly deteriorated. He developed respiratory failure necessitating artificial ventilation within three months after the onset of the disease. His father developed muscle weakness and atrophy of the upper extremities at age 70, and his cousin developed muscle weakness of the legs at age 41. Their conditions rapidly progressed to quadriplegia. CSF and electrophysiological findings were similar to those of the proband. Treatments by steroid pulse therapy, IVIg, and plasmapheresis were not effective. The father and cousin also required artificial ventilation within 3-4 months from the onset of symptoms, and became locked-in state. Autosomal dominant amyotrophic lateral sclerosis (AD-ALS) was considered, but SOD1 gene mutation was not detected. The present pedigree may have familial ALS caused by a gene mutation other than SOD1.

Adult↗

Muscle strengthening in a post-polio subject through a high-resistance weight-training program.

A 48-year-old woman started experiencing increased muscle weakness and fatigue at age 44, 40 years after the onset of acute poliomyelitis. The acute poliomyelitis resulted in severely weak lower limb muscles and as a result, she had used crutches for more than 40 years. Computer-aided force transducer systems were used to determine isometric muscle strength. Both quadriceps and left ankle dorsiflexors were severely weak and could not generate any measurable force. Isometric muscle strength of her right ankle dorsiflexors was 77 Newtons (N) (approximately 1/3 normal); isometric muscle strength of right elbow flexors (171N) and left elbow flexors (160N) were within normal range, although she complained of weakening based on her inability to climb two stairs at a time with crutches as she was used to. She underwent high-resistance weight training of her right ankle dorsiflexors and left elbow flexors for one year. Weight training was three times per week, five sets of ten repetitions per session; total duration of muscle contraction (excluding rest periods) was two and one half minutes per session, 30 minutes per month. Muscle strength (N) was remeasured after four, eight, and 12 months. Muscle strength of right ankle dorsiflexors increased by 61%, whereas that of the left elbow flexors increased by 32% after one year of weight training. She also expressed a subjective feeling of increased muscle strength. High-resistance, short duration muscle strengthening exercise programs should therefore be given a serious consideration in the rehabilitation management of moderately weak muscles of post-polio subjects.

Exercise Therapy↗

Steroid myopathy in cancer patients.

We prospectively evaluated 15 adult cancer patients being treated with adrenocorticosteroids (steroids) to determine the frequency and time course of "steroid myopathy." Nine (60%) developed clinically detectable proximal muscle weakness that, in six, was severe enough to interfere with activities of daily living. Proximal muscle weakness developed within 15 days in eight of nine patients and was significantly related to the cumulative dose of steroid. Eight of nine patients with proximal muscle weakness, and two of six without such weakness, experienced a significant decline in respiratory function, leading to symptomatic dyspnea in four patients of the former group. In three patients who could be followed for more than 3 months off steroids, there was either improvement or resolution of the weakness and, when present, of the respiratory impairment. Steroid myopathy is a common complication among cancer patients receiving steroids. It can often affect respiratory function even when proximal limb muscles remain strong. Clinical recognition is important since steroid myopathy can lead to increased morbidity and may be reversible with reduction or discontinuation of steroids.

Adult↗

Effects of controlled inspiratory muscle training in patients with COPD: a meta-analysis.

The purpose of this meta-analysis is to review studies investigating the efficacy of inspiratory muscle training (IMT) in chronic obstructive pulmonary disease (COPD) patients and to find out whether patient characteristics influence the efficacy of IMT. A systematic literature search was performed using the Medline and Embase databases. On the basis of a methodological framework, a critical review was performed and summary effect-sizes were calculated by applying fixed and random effects models. Both IMT alone and IMT as adjunct to general exercise reconditioning significantly increased inspiratory muscle strength and endurance. A significant effect was found for dyspnoea at rest and during exercise. Improved functional exercise capacity tended to be an additional effect of IMT alone and as an adjunct to general exercise reconditioning, but this trend did not reach statistical significance. No significant correlations were found for training effects with patient characteristics. However, subgroup analysis in IMT plus exercise training revealed that patients with inspiratory muscle weakness improved significantly more compared to patients without inspiratory muscle weakness. From this review it is concluded that inspiratory muscle training is an important addition to a pulmonary rehabilitation programme directed at chronic obstructive pulmonary disease patients with inspiratory muscle weakness. The effect on exercise performance is still to be determined.

Breathing Exercises↗

Myofibrillar myopathy caused by novel dominant negative alpha B-crystallin mutations.

We here report the second and third mutations in alphaB-crystallin causing myofibrillar myopathy. Two patients had adult-onset muscle weakness. Patient 1 had cervical, limb girdle, and respiratory muscle weakness and died of respiratory failure. Patient 2 had proximal and distal leg muscle weakness. Both had myopathic electromyogram with abnormal electrical irritability and muscle biopsy findings of myofibrillar myopathy and mild denervation. Myofibrillar disintegration begins at the Z-disk and results in abnormal local expression of desmin, alphaB-crystallin, dystrophin, neural cell adhesion molecule (NCAM), and CDC2 kinase. Seven to 8% of nuclei display early apoptotic changes. Both patients carry a truncating mutation in the C-terminal region of alphaB-crystallin (464delCT in Patient 1 and Q151X in Patient 2) which is crucial for the solubilization and chaperone functions of the molecule. cDNA analysis shows the same mutations and no alternatively spliced transcripts. Immunoblots of muscle demonstrate increased expression of wild-type and reduced expression of the mutant protein. Immunoblots under nondenaturing conditions show that the mutant protein forms lower than normal molecular weight multimeric complexes with wild type. We conclude that (1) despite its reduced expression, the mutant protein exerts a dominant negative effect; (2) mutations in alphaB-crystallin are an infrequent cause of myofibrillar myopathy; (3) alphaB-crystallin-related myopathies display phenotypic heterogeneity.

Base Sequence↗

Respiratory function vs sleep-disordered breathing as predictors of QOL in ALS.

BACKGROUND: Most patients with ALS have evidence of respiratory muscle weakness at diagnosis, and death is usually due to respiratory failure. Sleep disruption, possibly due to apneas, hypopneas, orthopnea, or REM-related desaturation, is common. The relative impact of these factors on quality of life has not been established. METHODS: The authors recruited 23 subjects with probable or definite ALS. Quality of life was assessed using generic and specific instruments, and respiratory muscle strength by measurement of vital capacity, maximum static pressures, and sniff nasal inspiratory pressure. Twenty-two subjects underwent polysomnography. Overall limb and axial muscle strength was estimated using a summated muscle score based on the Medical Research Council clinical scale. RESULTS: On univariate analysis, there were moderate to strong correlations between quality of life and all measurements of respiratory muscle function (R = 0.42-0.82). The correlations with selected polysomnographic indices were weaker and less consistent (R = 0.44-0.59). Multivariate analysis showed that maximum static inspiratory pressure was the strongest independent predictor of quality of life. CONCLUSION: Quality of life was strongly and independently related to respiratory muscle function. Relations with polysomnographic indices were weaker and were attributable to respiratory muscle weakness. Respiratory muscle weakness is much more important than the frequency of apneas and hypopneas in determining quality of life in ALS.

Adult↗

Pulmonary dysfunction and reduced exercise capacity in patients with myelomeningocele.

OBJECTIVE: To evaluate pulmonary function and exercise capacity in children with myelomeningocele. STUDY DESIGN: Prospective evaluation in a randomly selected cohort of 12 subjects (10 to 17 years of age) with myelomeningocele and 12 control subjects matched for age, sex, and arm span. METHODS: Spirometry, lung volumes, maximum respiratory pressures, maximum oxygen expenditure during arm ergometry, and anaerobic threshold were measured. RESULTS: Mean total lung capacity and fractional lung volumes were significantly lower in case subjects than control subjects. Eleven subjects (92%) had a reduced forced vital capacity; seven (58%) had restrictive disease as evidenced by reductions in total lung capacity with normal or increased forced expiratory volume in 1 second/forced vital capacity ratio. Nine subjects (75%) had respiratory muscle weakness as evidenced by reduced maximum respiratory pressures or a low maximum voluntary ventilation. Exercise capacity was reduced as evidenced by a lower maximum oxygen consumption at peak exercise (13.8 +/- 4.8 vs 21.3 +/- 7.5 ml/min per kilogram of body weight; p < 0.02) and a lower anaerobic threshold (12.4 +/- 5.1 vs 17.3 +/- 4.2 ml/min per kilogram; p < 0.01) than the control group. Though the majority of subjects with myelomeningocele had a significant degree of restrictive disease, respiratory muscle weakness, or both, only one subject had pulmonary symptoms during exercise. CONCLUSIONS: Though most subjects with myelomeningocele had a significant degree of restrictive lung disease, respiratory muscle weakness, or both, exercise capacity was mostly limited by arm weakness. Skeletal muscle weakness may mask the symptoms of an underlying pulmonary abnormality, which may not be evident unless a pathologic cause of increased ventilation is present. Pulmonary function testing is suggested to screen for these abnormalities.

Adolescent↗

Prednisone-responsive limb-girdle syndrome: a special disorder?

An eight-year-old boy had non-familial generalized muscle weakness, greater in the girdle and proximal limb muscles, sparing eye and face. It was insidiously progressive from age 14 months to age 20 months and then static, with major weakness. Two biopsies from very weak muscles, showed only type II muscle fiber atrophy. Muscle carnitine was normal. The EMG was "myopathic". Edrophonium test, antibodies to achR and systemic curare test were negative. There was a dramatic clinical improvement with prednisone, sustained now seven years later. Neither the pathogenesis nor cell mainly affected (neuron or muscle) is known. Not typical of a known disease, this unique patient demonstrates the potential therapeutic importance of steroid trial in patients with a severe chronic "limb-girdle syndrome" whose electro-physiology is non-specific and the muscle morphology shows changes "too minimal" to explain severe muscle weakness.

Biopsy↗

[Two cases of neuralgic amyotrophy].

Case 1: A 27-year-old man had a fever of 38 degrees C, followed by acute onset of bilateral upper arm pain. Two days later severe muscle weakness in bilateral upper arms appeared and he was admitted to our hospital. On admission, severe atrophy of the left deltoid and mild atrophy of the right deltoid were observed, with severe muscle weakness in bilateral deltoid and mild weakness in other parts of upper extremities. Tendon reflexes were decreased in the upper extremities. Sensation was intact. CSF showed mild pleocytosis. Nerve conduction velocity was normal and electromyography showed mild NMU decrease in upper extremities. Muscle biopsy of the right deltoid one month after the onset was normal. Muscle weakness began to improve 3 months after the onset, with only mild weakness at 10 months. Case 2: A 60-year-old man had acute onset of left shoulder and upper arm pain, followed by muscle atrophy and weakness of the left upper arm. He showed marked atrophy of the left deltoid, moderate atrophy of the left biceps and left scapular region, and severe muscle weakness in the left upper arm. Deep tendon reflexes were absent in the left upper extremity. Sensation was intact. Nerve conduction velocity was normal and electromyography showed marked NMU decrease in the left upper arm. Muscle biopsy of the left biceps 4 months after the onset showed grouped atrophies on HE staining, type 2 fiber atrophies on routine ATPase staining, and many targetoid atrophic fibers on NADH-TR staining. Muscle weakness began to improve slowly 6 months after the onset, but considerable weakness persisted at 10 months. Detailed muscle biopsy findings in neuralgic amyotrophy have not been documented. Muscle biopsy of Case 2 showed marked neurogenic changes compared to Case 1, which may be associated with the difference in clinical course between the two cases.

Adult↗

[An adult case of recurrent myelopathy presenting with monoplegia following asthmatic attacks].

A 22-year-old woman noticed an acute onset muscle weakness in her right leg after an asthmatic attack. A neurological examination showed moderate muscle weakness from the right iliopsoas muscle to the toe muscles, a decreased deep tendon reflex in her right lower limb and mild hypesthesia in her right L2-S1 segments. Needle EMG revealed fibrillation potentials in the right gastrocnemius muscle and a positive sharp wave in the right anterior tibialis muscle. The findings of motor nerve conduction studies and sensory nerve conduction studies were normal. The lesion was considered to be located at the posterior horns, as well as at the anterior horns at the L2-S1 levels and also at their roots on the right side. The anterior horn cells appeared to be the most severely affected. Polio-, echo-, entero- and coxsackie-virus antibody titers showed no significant changes on the 36th and 64th days of the disease. The serum IgE level was elevated and mite antigen-specific IgE was strongly positive. MRI revealed no abnormalities in either the thoracic or lumbar spinal cord. Although the sensory disturbance did rapidly improve after corticosteroid therapy, no improvement was seen in her muscle weakness which thus resulted in the atrophy of the affected muscle. While undergoing the corticosteroid therapy, she suffered another asthmatic attack. Nine days after the second attack, she further developed weakness in her right deltoid, biceps brachii, triceps brachii, wrist extensor, wrist flexor, digits extensor and digits flexor muscles with hyperreflexia in her left upper limb. Cervical MRI disclosed a high intensity area at the C3-6 level on the T2-weighted images and also a gadolinium enhancement of the lesion. Since monoplegia had appeared twice previously after bronchial asthma attacks in this case, Hopkins syndrome was suggested. Hopkins syndrome has so far been exclusively reported in children, and no recurrent cases have ever been reported with this condition. This is therefore considered to be the first case of Hopkins syndrome occurring in an adult and also demonstrating recurrence.

Adult↗

Methioninemia and myopathy: a new disorder.

A 7 1/2-year-old girl with hypermethioninemia, myopathy, and mental deficiency (IQ = 65) is described. The increased methionine was not associated with deficiency of methionine adenosyltransferase, which was normal or increased in liver, muscle, erythrocytes, and cultured fibroblasts. Methionyl-tRNA synthetase in fibroblasts was normal. The hypermethioninemia and a concurrently increased blood S-adenosylmethionine declined on a diet low in methionine. There was a diffuse, symmetrical, moderate proximal muscle weakness, but muscle atrophy was not discernible, and the deep tendon reflexes were hypoactive but obtainable. Electromyographic abnormalities were not detected. Electron microscopy of muscle revealed 3 to 6 small myelin figures in the region of the I band in nearly every fiber, with occasional myelin figures at other sites also. These myelin figures were more numerous and smaller than those seen accompanying nonspecific myopathies and may reflect a more specific pathological change. Electron microscopy of liver revealed three nonspecific lesions in all hepatocytes: (1) numerous megamitochondria with crystalloid deposit in the matrix; (2) increased numbers of small vesicles of smooth endoplasmic reticulum; and (3) loss of plasma membrane microvilli, with extensive bleb formation and shedding of cytoplasm into Disse's space.

Amino Acid Metabolism, Inborn Errors↗

Human immunodeficiency virus (HIV)-associated myopathy: immunocytochemical identification of an HIV antigen (gp 41) in muscle macrophages.

In a patient with acquired immunodeficiency disease syndrome (AIDS) and muscle weakness, a muscle biopsy specimen disclosed degeneration of muscle fibers, regeneration, and focal endomysial mononuclear inflammation. A conspicuous feature was the presence of perivascular macrophages within the endomysium that showed positive immunostaining for human immunodeficiency virus (HIV) (gp 41) antigen. HIV was not detected within myofibers. Our findings suggest an important role for the HIV-infected macrophage in the pathogenesis of this myopathy.

Acquired Immunodeficiency Syndrome↗

Hypothyroid neuropathy and myopathy: clinical and electrodiagnostic longitudinal findings.

The clinical and electrodiagnostic findings before and during 6 years of therapy are reported in a 59-year-old man with severe hypothyroidism. He had severe sensory neuropathy, carpal and tarsal tunnel syndromes, mild motor neuropathy and moderately severe myopathy. The sensory signs and symptoms disappeared in the 3rd and 4th years of treatment, respectively. Muscle cramps and pain subsided within 2 years, but mild proximal muscle weakness and atrophy persisted. The sensory distal latencies remained slightly prolonged and the electromyographic changes improved. This case shows that thyroid hormone replacement eliminates the neuropathic manifestations of severe hypothyroidism. In contrast, the myopathic features, such as weakness and muscle wasting, may persist despite maintenance of the euthyroid state.

Electrodiagnosis↗

Ultrastructure of the syndrome of continuous muscle fibre activity.

The ultrastructure of muscle and the myoneural junction of a man of 60 suffering from the syndrome of continuous muscle fibre activity was studied. This syndrome is manifested by disturbances of walking, muscle weakness, permanent muscle contractions and involuntary movements. The myoneural junction was hypertrophied and showed ramifications of the secondary clefts. The presynaptic nerve ending contained no synaptic vesicles. The relationship of these findings to the disease is discussed.

Gait↗