Showing papers by "Mark Hallett published in 1981"
01 Jan 1981
TL;DR: This chapter discusses information that is available on the clinical manifestations of myoclonus and the diseases that cause the syndrome.
Abstract: Publisher Summary This chapter discusses information that is available on the clinical manifestations of myoclonus and the diseases that cause the syndrome. Myoclonus must be distinguished from other dyskinesias. The history of myoclonus is intertwined with that of epilepsy and most movement disorders, and it is necessary to review a great deal of the history of neurology to understand how the various terms arose. The term myoclonus was first used in a case report by Friedreich in 1881, when he described the syndrome of paramyoclonus multiplex. Despite considerable experimental and clinical neurophysiological study, understanding of the pathophysiology of the many varieties of myoclonus encountered in clinical practice is not complete.
171 citations
TL;DR: The battery found 100% abnormality in the definite patients and 82% in the indefinite patients and somatosensory evoked potentials were most often abnormal: 86% in definite patients, 58% in indefinite patients, and 77% in asymptomatic definite patients.
Abstract: Thirty patients with definite multiple sclerosis and 50 patients in whom the diagnosis was suspected but not proved (indefinite multiple sclerosis) were studied with visual evoked potentials from each eye, somatosensory evoked potentials from each limb, brainstem auditory evoked potentials from each ear, and the blink reflex. The purpose was to organize a battery of clinically practical tests. The battery found 100% abnormality in the definite patients and 82% in the indefinite patients. Of the individual tests, somatosensory evoked potentials were most often abnormal: 86% in definite patients, 58% in indefinite patients, and 77% in asymptomatic definite patients. Visual evoked potentials were abnormal in 76%, 55%, and 40% of the same three categories. Brainstem auditory evoked potentials and the blink reflex were abnormal less often but contributed to the efficacy of the battery.
91 citations
TL;DR: The abnormal polysaccharide in PFK deficiency may be related to greatly elevated concentration of muscle glucose-6-phosphate, an activator of the chain-elongating enzyme glycogen synthase.
Abstract: A 61-year-old woman with muscle phosphofructokinase (PFK) deficiency had mild limb weakness all her life but no cramps or myoglobinuria. For 5 years the limb weakness progressed. In muscle, PFK activity was 1% of normal and glycogen concentration was elevated (2.13%). By light microscopy, a minor component of the accumulated glycogen appeared as PAS-positive, diastase-resistant inclusions in 10% of muscle fibers. The inclusions had a filamentous fine structure that resembled the abnormal long-chain glycogen of brancher enzyme deficiency. Iodine absorption spectra of both the inclusions and a diastase-resistant fraction of isolated glycogen resembled amylopectin. The abnormal polysaccharide in PFK deficiency may be related to greatly elevated concentration of muscle glucose-6-phosphate, an activator of the chain-elongating enzyme glycogen synthase.
74 citations
TL;DR: Attempts to elicit stretch reflexes from the 'relaxed' human long thumb flexor were made at various times prior to the onset of a voluntary contraction of that muscle, finding a small long-latency response, which occasionally increased in amplitude as the time for voluntary activation approached.
22 citations
5 citations
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TL;DR: Presentation of Case A 76-year-old woman was admitted to the hospital because of a neurologic disorder and found that a tender nodule developed on the nasal bridge and ...
Abstract: Presentation of Case A 76-year-old woman was admitted to the hospital because of a neurologic disorder. She was well until two years earlier, when a tender nodule developed on the nasal bridge and ...
1 citations
TL;DR: Experience with more complete neurophysiologic testing reveals a distinct pattern suggestive of subacute combined degeneration, which correlates well with the clinical features and the known pathologic finding.
Abstract: To the Editor.— Troncoso et al and Rees (Archives1979;36:168-169 and 1980;37:397) have reported prolonged latencies of the major positive component (P 2 ) of the visual evoked response in patients who have subacute combined degeneration resulting from pernicious anemia. Our experience with more complete neurophysiologic testing reveals a distinct pattern suggestive of subacute combined degeneration, which correlates well with the clinical features and the known pathologic finding. 1 The visual evoked response is not the most sensitive parameter. One of the three patients described and one additional patient seen since that time have shown normal visual evoked responses. The most sensitive parameter, which has been abnormal in all cases, is the somatosensory evoked response. A full battery of studies showing an axonal degeneration peripheral neuropathy, normal brainstem auditory evoked responses, mildly abnormal visual evoked responses, and clearly abnormal somatosensory evoked responses paint a picture that is compatible with the diagnosis