Objective:

NA

Background:

Metronidazole induced encephalopathy (MIE) is a complication of prolonged metronidazole use whose clinical and radiographic signs are well-documented. Metronidazole is generally a well-tolerated antibiotic but can rarely cause neurotoxicity in susceptible individuals. We report on a patient who developed MIE that did not initially resolve with metronidazole discontinuation, but which responded dramatically to high dose intravenous (IV) thiamine supplementation.

Design/Methods:

A 60- year-old woman developed confusion and gait disturbance two weeks prior to admission. She had presented to an outside hospital with colitis one month prior and was treated with a 28-day course of IV ciprofloxacin and metronidazole, along with TPN. She had developed confusion and dystaxia after initiation of IV antibiotics that persisted after metronidazole discontinuation, and which led her to return to hospital. Neurologic exam revealed confusion and dystaxia. Given the recent TPN use, a thiamine level was drawn, and she was treated empirically with thiamine 500mg IV daily. MRI brain revealed restricted diffusion of the splenium of corpus collosum and increased T2-signal of the bilateral dentate nuclei. After two doses of IV thiamine, her dystaxia and confusion improved, and she regained her neurologic baseline. The diagnosis of MIE complicated by thiamine deficiency was made. Her thiamine level in serum resulted as normal.

Results:

na

Conclusions:

The patient’s MRI brain revealed classic changes of MIE yet she did not improve after cessation of metronidazole as described in previously reported cases. Rather, she improved after treatment with high dose thiamine. Metronidazole acts as a thiamine analogue and inhibits the absorption of thiamine leading to a functional deficiency state. We hypothesize that metronidazole, in the context of the patient’s suspected malnutrition, led to a severe functional thiamine deficiency, despite having a normal thiamine serum level. This case highlights the importance of thiamine repletion in addition to metronidazole discontinuation when MIE is suspected.