Muscle & nerve
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Mononeuropathies associated with orthotopic liver transplantation were evaluated in a prospective manner. Ten percent of liver transplant recipients were noted to have focal peripheral nerve lesions in the postoperative period. ⋯ No brachial plexus injuries occurred. Diabetes and alcoholism were not risk factors for the development of a mononeuropathy.
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The spectrum of neuromuscular disorders among intensive care unit (ICU) patients has shifted toward disorders acquired within the ICU and away from "traditional" neuromuscular disorders that lead to ICU admission. We sought to assess this spectrum by determining the causes and relative frequencies of neuromuscular disorders that led to electromyography (EMG) examinations in our ICU population. Ninety-two patients were studied over a 4 1/2-year period. ⋯ Thirty-nine (42%) developed acute myopathy (consistent with critical illness myopathy in most), and 13% developed acute axonal sensorimotor polyneuropathy (mainly critical illness polyneuropathy). Patients with acute myopathy and acute axonal sensorimotor polyneuropathy had similar functional outcomes. We conclude that among patients who underwent EMG in our ICU population, acute myopathy is three times as common as acute axonal polyneuropathy, and the outcomes from acute myopathy and acute axonal polyneuropathy may be similar.
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Comparative Study
Fasciculation potentials: a study of amyotrophic lateral sclerosis and other neurogenic disorders.
We studied fasciculation potentials in amyotrophic lateral sclerosis (ALS), and in other neurogenic disorders, in strength and single-fiber electromyography-matched muscles. Benign fasciculations were studied in 3 normal subjects. Fasciculations were more stable and easier to recruit voluntarily in the early phase of ALS; later, fasciculations were more unstable, more complex, and less likely to be voluntarily recruited. ⋯ Benign fasciculations have a high firing rate and normal morphologic parameters. In ALS fasciculations arise proximally early in the disease and distally in the later stages. Fasciculation may be important in excitotoxic cell death in ALS.
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Clinical Trial Controlled Clinical Trial
Myoblast implantation in Duchenne muscular dystrophy: the San Francisco study.
We evaluated myoblast implantation in 10 boys with Duchenne muscular dystrophy (DMD) and absent dystrophin (age 5-10 years) who were implanted with 100 million myoblasts in the anterior tibial muscle of one leg and placebo in the other. Cyclosporine (5 mg/kg/day) was administered for 7 months. Pre- and postimplantation (after 1 and 6 months) muscle biopsies were analyzed. ⋯ There was increased force generation in both legs of all boys, probably due to cyclosporine. Using the polymerase chain reaction, evidence of myoblast survival and dystrophin mRNA expression was obtained in 3 patients after 1 month and in 1 patient after 6 months. These studies suggest a salutary effect of cyclosporine upon muscular force generation in Duchenne muscular dystrophy; however, myoblast implantation was not effective in replacing clinically significant amounts of dystrophin in DMD muscle.
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Vertex transcranial magnetic stimulation (TMS) elicited tibialis anterior motor evoked potentials (MEPs) and silent periods (SPs) that were recorded during and following isometric maximal volitional contraction (MVC). During MVC in 6 healthy subjects, MEP amplitudes in the exercised muscle showed an increasing trend from an initial value of 4539 +/- 809 muV (mean +/- SE) to 550 +/- 908 muV (P < 0.13) while force and EMG decreased (P < 0.01). Also, SP duration increased from 165 +/- 37 ms to 231 +/- 32 ms (P < 0.01). ⋯ This SP prolongation was focal to the exercised muscle. Silent periods recorded after pyramidal tract stimulation were unchanged following the MVC. These results suggest that MEP and SP might have common sources of facilitation during an MVC and that inhibitory mechanisms remain focally augmented following a fatiguing MVC.