Biomedical subjects
Publications and source records attributed to C Melmed.
Progressive myoclonus epilepsy (PME) may develop in adult life. We present two patients with PME appearing around the age of 30 years in whom the disorder represented a manifestation of Alzheimer's disease. This diagnosis must be considered in addition to possible Kufs' disease or myoclonic epilepsy with ragged red fibers (MERRF) when PME develops in young adults.
We evaluated biofeedback rehabilitation in patients with severe chronic unilateral facial paralysis, who had intact facial-motor innervation (House grades 3 to 5). Recovery of facial function was characterized (1) by grading facial movement symmetry, and (2) by counting the number of muscles exhibiting synkinesis during maximal execution of selected facial movements (e.g., smiling). Facial function in 21 patients typically improved by one House grade. Facial symmetry recovered rapidly during the first 5 months of treatment, and then improved more slowly. However, during this latter period, examination of the relationship between symmetry and synkinesis (visualized by a graph plotting symmetry grades on the x-axis, against the number of synkinetic muscles on the y-axis) indicated that overall facial control was improving even when House grading suggested that it was not. Such information should aid facial retraining and may clarify understanding of underlying rehabilitation mechanisms.
Multiple symmetrical lipomatosis is a striking clinical finding associated with a variety of peripheral and central nervous system abnormalities. We describe 4 unrelated patients with evidence of mitochondrial dysfunction in skeletal muscle. Multiple symmetrical lipomatosis is an additional, albeit unusual, manifestation of the expanding clinical spectrum of mitochondrial diseases.
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Three patients with a monoclonal IgM kappa paraproteinemia had a slowly progressive segmental demyelinating peripheral neuropathy. Sural nerve biopsies showed predominantly large fiber loss, with widening of the intraperiod line of myelin associated with active demyelination. Immunoblot analysis showed reactivity of IgM to myelin-associated glycoprotein (MAG) of human myelin. An enzyme-linked immunosorbent assay (ELISA) was developed to provide a simple quantitative technique for detection of antibodies to MAG. Treatment with corticosteroids, immunosuppressive agents, and plasmapheresis produced no significant improvement.
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Conduction velocities of the proximal segments of the median and ulnar nerves were measured by evoking F-wave responses. The results of these and conventional motor and sensory studies from 60 control subjects were compared with the results in 30 patients with carpal tunnel syndromes, 18 patients with cubital tunnel syndromes, and 23 patients with suspected proximal entrapments. Sixty-seven percent of patients with proximal lesions (confirmed by myelography in 60 percent of cases) had abnormalities in their F-wave studies. Conventional motor studies were normal. Twenty-three percent of the patients with carpal tunnel syndrome and 11 percent of the patients with cubital tunnel syndrome also had abnormal F-wave studies, indicating an additional element of proximal entrapment. This technique is felt bo be useful in differentiating between distal and proximal entrapments.
The propagation velocities and conduction times of nerve impulses responsible for muscle F-waves were measured in the proximal segments of 60 normal posterior tibial nerves and of 41 normal peroneal nerves. The results were compared with those of 25 patients having confirmed lumbosacral root compression due to disc degeneration. Using the peroneal nerve, 65 per cent of patients had a prolonged proximal conduction time; a similar abnormality was found in 56 per cent of patients when the posterior tibial nerve was studied. The yield of positive results rose to 85 per cent and 76 per cent respectively when the M- and F-latencies in given individuals were compared. It was also shown that in normal subjects the F-response has a longer latency, and slower conduction velocity than the H-reflex when both are obtained using the same stimulating and recording sites. In patients in whom the ankle jerks and H-reflexes are absent, the F-waves may still be recorded indicating that the latter are mediated through motor fibers.
Two uncouplers of mitochondrial oxidative phosphorylation [2,4-dinitrophenol (DNP) and carbonylcyanide-m-chlorophenylhydrazone (CCCH)] were infused intra-arterially into a branch of the lower abdominal aorta of anesthetized rats over a 60-180 min period. An acute, severe, hypermetabolic state with systemic lactic acidosis and stiffness of the lower extremeities developed. In the plantaris muscles, by histochemistry, numerous "ragged red" fibers were present after the infusion. The "ragged red" areas presumably represented an absolute increase in mitochondrial mass in affected muscle fibers. By electron microscopy, linear inclusions were present in the intracristal space of many mitochondria. Simultaneous infusion of DNP and chloramphenicol, an inhibitor of mitochondrial protein synthesis, prevented the formation of ragged red fibers but not the intracristal inclusions. Infusion of relatively large amounts of oleic acid produced histochemical and electron-microscopic changes similar to those caused by the uncouplers. A possible pathogenesis of these reversible mitochondrial changes was discussed and their potential relevance to morphologic abnormalities of skeletal muscle mitochondria in human diseases was reviewed.
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Muscle biopsies from two patients revealed that numerous type 2 fibers contained large abnormal areas filled with cylindrical spirals. The cytochemical profile of these cylindrical spirals was sufficiently characteristic that they could be distinguished from tubular aggregates. Their electron microscopic appearance was unmistakable. Their origin and significance are uncertain. The diverse nature of the patients' conditions (cramps and malignancy, and an unusual form of spinocerebellar degeneration) indicate that these abnormal structures are not disease specific.