Peripheral Neuropathy Induced by a Short Course of Metronidazole: A Case Report of Diagnostic Challenge

Area of Science:

• Pharmacology
• Neurology
• Infectious Diseases

Background:

• Metronidazole is a widely used antibiotic known for its safety and cost-effectiveness.
• While generally safe, metronidazole can rarely induce neurotoxicity, including peripheral neuropathy and encephalopathy.
• Existing literature often links metronidazole neurotoxicity to prolonged therapy (>4 weeks) and high cumulative doses (>42g), though a precise dose-response relationship remains unclear.

Purpose of the Study:

• To report a rare case of metronidazole-induced peripheral neuropathy.
• To describe the clinical presentation, diagnostic findings, and outcome in a patient experiencing neuropathy at a lower cumulative metronidazole dose than previously documented.
• To discuss the potential mechanism of metronidazole neurotoxicity, specifically demyelination, in contrast to commonly reported axonal degeneration.

Main Methods:

• Case report of a 41-year-old male treated for a liver abscess with metronidazole.
• Clinical assessment and neurological examination.
• Nerve conduction studies (NCS) to evaluate peripheral nerve function.
• Exclusion of other potential causes of neuropathy.

Main Results:

• The patient developed peripheral neuropathy after a cumulative metronidazole dose of 12g, significantly lower than typically associated with toxicity.
• Nerve conduction studies revealed a sensorimotor demyelinating polyneuropathy affecting all four limbs.
• Neuropathy symptoms improved within 5 days of discontinuing metronidazole, confirming the drug as the likely cause.

Conclusions:

• Metronidazole can induce peripheral neuropathy even at cumulative doses lower than those generally considered high-risk.
• The observed demyelinating pattern in nerve conduction studies aligns with some literature, suggesting demyelination as a potential mechanism of metronidazole neurotoxicity.
• This case underscores the importance of considering metronidazole as a potential cause of peripheral neuropathy, regardless of cumulative dose, and highlights the need for further research into its neurotoxic mechanisms.