Neurology
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Two hundred and fifty consecutive patients were evaluated for myasthenia gravis with repetitive supramaximal stimulation of peripheral nerves and regional curare administration when necessary. Among patients with definite generalized myasthenia gravis, 72 percent had abnormal responses to repetitive supramaximal stimulation alone and another 17 percent had abnormal responses after regional curare administration. ⋯ Myasthenia gravis has not developed subsequently in any of the equivocal patients with negative electric tests. We have found these electric procedures to be simple, safe, and at least as effective as other methods in diagnosing myasthenia gravis.
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In a series of 72 patients with disease of peripheral neurons, neuropathic painfulness of the foot was found to be related to the rate and kind of nerve fiber degeneration. Patients with acute breakdown of myelinated fibers (either by wallerian or axonal degeneration) tend to have pain more often and to a greater degree than do patients with more chronic forms of nerve fiber degeneration. Neuropathic painfulness was not found to be related simply to the ratio of remaining large and small fibers after nerve fiber degeneration. These studies do not fit the expectation of the proponents of the gate theory of pain.
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Highly sensitive enzymatic assays, microdissection techniques, and histochemical methods were used to investigate the effects of blunt trauma on rabbit spinal cord serotonin, norepinephrine, and dopamine concentrations. Within 5 minutes after trauma, norepinephrine and serotonin in gray matter decreased considerably at the lesion center. ⋯ No changes in dopamine concentration were detected. Substantial changes in monoamines do occur after spinal cord trauma and serotonin may play a role in injury development.
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Clinical Trial Controlled Clinical Trial
Effect of propranolol on essential tremor.
The investigators tested the effect of 120 mg propranolol daily on 21 patients with essential tremor using a double-blind cross-over method and electrical recording of tremor amplitude and frequency. The patients varied in age between 15 and 60 years and had a mean tremor frequency of 10 cps. Propranolol had no effect on the tremor frequency but reduced the amplutide in 15 of the patients. Propranolol was most effective in older patients and in those with slow tremor frequencies.
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In seven cases of Huntington's chorea, the ventrolateral thalamus was studied by quantitative cytometry. A selective 50 percent atrophy of microneurons (internuncial cells) was found while the macroneurons did not show significant atrophy. Thalamic microneurons might be presynaptic and postsynaptic inhibitory cells. Their specific atrophy in Huntington's chorea thus could be related to the known decrease of gamma aminobutyric acid (GABA) in Huntington's chorea.