Muscle Rigidity in a Newborn Due to Continuous Peripheral Nerve Hyperactivity

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Abstract
This report describes a patient born with generalized muscle stiffness. The electromyogram (EMG) revealed continuous electrical activity during rest, sleep, general anesthesia, spinal anesthesia, and peripheral nerve block. The muscle rigidity and EMG activity were abolished by tubocurarine chloride, proving that the disorder was due to hyperactivity of the peripheral nerves. Motor conduction velocity was unobtainable in the peroneal nerve and histochemical type II fibers were completely lacking in muscle. Autopsy revealed reactive astrocytosis in the subcortical white matter of the cerebrum, no motor neuron abnormality, demyelination, and axonal swelling in the peripheral nerves and changes of denervation in the skeletal muscles. Gas chromatography analysis demonstrated increased serum content of 2, 2-bis-(p-chlorophenyl)-1, 1-dichloroethylene (a metabolite of the pesticide 2, 2-bis-(p-chlorophenyl)-1, 1, 1-trichloroethane, but the significance of the elevated pesticide level is uncertain. Fifteen similar cases have been reported in the literature since 1961, but this case is unique, because it occurred in a newborn, because the child died as a result of the muscle rigidity, and because of the abnormalities in peripheral nerve and muscle.