The evaluation of a new synthetic pyrethroid pesticide (permethrin) for neurotoxicity.

A new synthetic pyrethroid, permethrin, has recently been granted a registration by the United States Environmental Protection Agency. Permethrin and a large number of other chemicals of its type are expected to receive widespread use in the environment in the near future. Since the mechanism by which these compounds exert their toxic effect in insects (and at higher doses in mammals) is by disruption of the normal function of nervous tissue, a detailed morphologic evaluation of the nervous system was performed on rats from two long-term feeding studies conducted on permethrin.

Neurogenic arthropathy and recurring fractures with subclinical inherited neuropathy.

Some patients with radiologic findings of neurogenic arthropathy or multiple fractures do not exhibit overt neurologic signs. Results of nerve conduction velocity, computer-assisted sensory examination, periosteal nociception, and morphometric and graded teased-fiber evaluation of cutaneous nerves allowed us to recognize a mild neuropathic abnormality. Neurogenic arthropathy and subclinical neuropathy were also found in relatives.

Prednisone improves chronic inflammatory demyelinating polyradiculoneuropathy more than no treatment.

Of 40 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), 28 completed a controlled three-month trial of prednisone. Prednisone was shown to cause a small but significant improvement over no treatment in scored neurological disability, some measures of computer-assisted sensory detection threshold, graded muscle strength, and some attributes of nerve conduction. No subset of patients was more likely than another to be responsive to prednisone; those with a progressive course were as likely to be responsive as recurrent cases.

Intensive evaluation of referred unclassified neuropathies yields improved diagnosis.

Intensive evaluation of 205 cases of undiagnosed neuropathy in a center with special approaches and facilities permitted classification of 76% of the patients. Inherited disorders accounted for 42% of the series, 21% of the patients were shown to have inflammatory-demyelinating polyradiculoneuropathy, and 13% had neuropathies associated with other disorders. A considerable improvement in diagnosis was possible from evaluation of the kin of the patients with undiagnosed neuropathy.

Nitrous oxide neurotoxicity studies in man and rat.

To assess the effects of chronic exposure to low levels of nitrous oxide on neural function of man, the authors evaluated the neurologic condition, motor and sensory nerve conduction, and computerized tests of sensation of approximately half of the dentists in Rochester, Minnesota. Results of scored tests of neural function were not significantly different for dentists who used nitrous oxide extensively in their practices and dentists who did not. To assess the effects of chronic exposure to high levels of nitrous oxide on neural function and structure of experimental animals, groups of rats were exposed to 70 per cent N2O in 30 per cent oxygen for four hours, five days a week, for six months.