Neurophysiologic Studies of Patients with Crohn's Disease on Long-Term Treatment with Metronidazole

Abstract

Fifty-three patients with Crohn's disease were chosen for this study. They were divided into three groups: the first group (19 patients) was treated with metronidazole and had been receiving the drug for at least 1 year; the second group (13 patients) had previously had the same type of long-term treatment but had been off the drug for at least 3 months before entering the study; the third group (21 patients) had never received treatment with metronidazole. The maximum daily dose of metronidazole used was 800 mg. All patients were examined with a broad set of neurophysiologic investigations devised to reveal signs of peripheral neuropathy. No significant difference was found between the three groups. The conclusion was that a daily dose of metronidazole not exceeding 800 mg is well tolerated by patients with Crohn's disease with regard to objective signs of neurotoxicity. A few patients from all three groups showed a raised perception threshold for changes of temperature in the feet (as compared with the department's normal standard). The results of the test were almost identical in the three groups and thus not connected with the metronidazole treatment. During the study, patients were asked about subjective neurologic symptoms such as tingling and numbness. A few patients from all three groups reported such paresthesias from time to time, but they were of a transient nature, not perpetual, and, in patients taking metronidazole, not aggravated despite continuing treatment with unchanged dose. These symptoms and the raised perception threshold for temperature may be an effect of the inflammatory bowel disease itself. In the departments taking part in this study four patients receiving long-term treatment with metronidazole who complained of uninterrupted and increasing paresthesias had been seen before the start of the study. In these patients too the maximum daily dose had been 800 mg. The subjective symptoms disappeared within weeks after discontinuation of the treatment or dose reduction. Neurophysiologic examination 20 days to 1 year later did not show any signs of peripheral neuropathy. In these patients a reversible toxic neuropathy was assumed to have existed and to have faded after dose reduction or discontinuation of drug treatment. The rapid disappearance of symptoms was considered to make axonal degeneration improbable.

Key Words:

• Crohn's disease
• metronidazole neuropathy