Bilateral diaphragmatic paralysis and related respiratory complications in a patient with West Nile virus infection.

The case report is presented of a patient with West Nile virus infection and ventilator dependent respiratory failure in whom bilateral diaphragmatic paralysis developed. If the prevalence of West Nile virus infection continues to rise, recognition of diaphragmatic paralysis and related respiratory complications will become increasingly important to the pulmonary/critical care physician.

31P MRS studies of exercising human muscle at high temporal resolution.

Methods for measuring mitochondrial activity from 31P magnetic resonance spectroscopy data collected during and after exercise were compared in controls, weight lifters, and peripheral vascular occlusive disease (PVOD) patients. There were trends toward increasing mitochondrial activity during exercise in order from PVOD patients, moderately active controls, highly active controls, to weight lifters. Results from PVOD patients show divergence of some measures due to 1) the non-exponential nature of phosphocreatine recovery, and 2) potential breakdown of [ADP] control of the mitochondria due to lack of oxygen (for Qmax calculation). These results demonstrate the utility of obtaining and directly analyzing high time resolution data rather than assuming monoexponential behavior of metabolite recovery.

Paraneoplastic motor neuron disease with type 1 Purkinje cell antibodies.

Autoimmune serological testing is a useful aid for identifying a paraneoplastic basis for sporadic motor neuron disease. A 67-year-old woman with ovarian carcinoma presented with progressive weakness. Neurological examination was suggestive of motor neuron disease with signs of upper motor neuron disorder. Electromyography revealed severe motor neuronopathy of the upper extremities. Characteristic type 1 Purkinje cell antibodies (anti-Yo antibody) was detected in the serum diluted at 1:61,400.

Combined aerobic training and dichloroacetate improve exercise capacity and indices of aerobic metabolism in muscle cytochrome oxidase deficiency.

There is no generally effective therapy for mitochondrial myopathies. In this study, we measured responses to combined aerobic training and oral dichloroacetate (DCA) therapy in a 25-year-old woman with a mitochondrial myopathy caused by cytochrome oxidase deficiency. The patient trained for 14 weeks, and DCA therapy was begun after 8 weeks. Independent indices of aerobic capacity and oxidative metabolism showed substantial improvement. Venous lactate concentrations at rest, and after a constant amount of work, decreased by approximately 50% after 8 weeks of aerobic training, and by more than 70% with the combination of training and DCA treatment. Heart rate at rest and after a constant amount of submaximal work decreased progressively. Aerobic capacity on a graded submaximal exercise test improved by 71% from baseline by the end of the treatment period. 31P magnetic resonance spectroscopy measurements of rate constants for recovery of muscle phosphocreatine increased 1.7-fold and metabolically active adenine diphosphate increased 2.8-fold after 8 weeks of training alone, and 4.5-fold and 23.0-fold after 14 weeks of training plus DCA treatment. Responses to the SF-36 Health Survey suggested a marked reduction in handicap. Thus, in this open study of a patient with cytochrome oxidase deficiency, a combination of aerobic training and DCA treatment resulted in substantial improvements in biochemical indices, exercise performance, and handicap. We conclude that exercise limitation in patients with mitochondrial myopathy may arise from effects of chronic deconditioning in addition to the effects of primary mitochondrial dysfunction and may be partially reversed by training and administration of DCA.

A distinctive type of infantile inflammatory myopathy with abnormal myonuclei.

Four infants developed progressive muscle weakness after a normal initial postnatal development. All patients had a moderate elevation of serum creatine kinase (CK) activity. Muscle biopsies revealed, in addition to myopathic features, endomysial and perivascular inflammation. Electron microscopy disclosed prominent myonuclear abnormalities. Corticosteroids in 3 patients were moderately beneficial. This appears to be a clinicopathologically distinct form of inflammatory myopathy of infants.