Atypical metronidazole-induced encephalopathy in anaerobic brain abscess

[A case of metronidazole-induced encephalopathy that is difficult to differentiate from Wernicke encephalopathy]

Herein, we present the case of a 76-year-old man diagnosed with an iliopsoas abscess 3 months prior and consequently administered metronidazole. The patient visited our facility complaining of difficulty in speaking and feeling unsteady when walking. Neurological findings showed dysarthria, nystagmus, and bilateral cerebellar ataxia. Head MRI-FLAIR demonstrated symmetrical hyperintensities in the bilateral cerebellar dentate nuclei, red nucleus, periaqueductal of the midbrain, periventricular third ventricle, and the corpus callosum. Although Wernicke's encephalopathy was among the differential diagnoses based on the imaging findings, the thiamine level was normal and improvement in symptoms and hyperintensity on FLAIR within 5 days of discontinuing metronidazole led to the diagnosis of metronidazole-induced encephalopathy. Although there were many similarities in the imaging findings of metronidazole-induced encephalopathy and Wernicke's encephalopathy, Metronidazole-induced encephalopathy should be initially considered when midbrain red nucleus lesions are observed.

S, Siddiqui SA, Gupta A, Pathak V, Mulani M, Khan S, Bansal T. MRI Findings and Topographic Distribution of Lesions in Metronidazole-Induced Encephalopathy

Purpose

This study aims to describe the magnetic resonance imaging (MRI) of the brain of five patients diagnosed with metronidazole-induced encephalopathy (MIE). In addition, the aim of our study was to better define the topographic distribution of lesions in MIE.

Methods

We retrospectively evaluated MRI findings before and after drug cessation in five patients diagnosed with MIE at Era’s Lucknow Medical College and Hospital, Lucknow, Uttar Pradesh, India. The main MRI signal changes and lesion locations were studied.

Results

Among the patients observed, the average age of the patients with MIE was 55 years (range: 30-70 years). Cerebellar dysfunction, mainly ataxia, and altered mental status were seen in the majority of cases. The most frequently involved sites were the dentate nucleus (cerebellum), brain stem, and corpus callosum (splenium). In diffusion-weighted imaging (DWI), most lesions did not show true restricted diffusion, except for a solitary corpus callosum lesion.

Conclusion

Although drug-related side effects are more common with long-term use of metronidazole, they may also occur with high doses for short durations. The dentate nucleus, the splenium in the corpus callosum, and the brain stem are the most affected structures. Apart from a solitary lesion of the corpus callosum, all identified lesions were reversible at follow-up MRI after discontinuation of metronidazole. The clinical presentation and characteristic MRI changes are highly specific and can be correlated to make a rapid and more accurate diagnosis of this potentially treatable condition. Prognosis is excellent if detected early.

Metronidazole-induced encephalopathy associated with treatment for liver abscesses

Metronidazole‐induced encephalopathy (MIE) is a rare condition in Japan. We report the case of a patient with MIE who presented with abducens paralysis and ataxia without underlying risk factors. A history of metronidazole (MNZ) administration and rapid improvement after MNZ discontinuation are important in making this diagnosis, and characteristic findings of magnetic resonance imaging support the diagnosis. MIE is expected to become common in Japan as the use of MNZ increases because of expanded insurance coverage. Therefore, MIE needs to be recognized as a differential diagnosis of the central nervous symptoms in patients taking MNZ.

Clinical and Neuroradiological Spectrum of Metronidazole Induced Encephalopathy: Our Experience and the Review of Literature

Metronidazole is an antimicrobial agent mainly used in the treatment of several protozoal and anaerobic infections, additionally, is often used in hepatic encephalopathy and Crohn disease. Apart from peripheral neuropathy, metronidazole can also cause symptoms of central nervous system dysfunction like ataxic gait, dysarthria, seizures, and encephalopathy which may result from both short term and chronic use of this drug and is collectively termed as "metronidazole induced encephalopathy"(MIE). Neuroimaging forms the backbone in clinching the diagnosis of this uncommon entity, especially in cases where there is high index of suspicion of intoxication. Although typical sites of involvement include cerebellum, brain stem and corpus callosum, however, lesions of other sites have also been reported. Once diagnosed, resolution of findings on Magnetic Resonance Imaging (MRI) of the Brain along with clinical improvement remains the mainstay of monitoring. Here we review the key clinical features and MRI findings of MIE as reported in medical literature. We also analyze implication of use of this drug in special situations like hepatic encephalopathy and brain abscess and discuss our experience regarding this entity.

Metronidazole-induced encephalopathy: not always a reversible situation

BACKGROUND

Metronidazole is a nitroimidazole antimicrobial drug prescribed to treat infections caused by anaerobic bacteria and protozoa. Uncommonly, it causes central nervous system (CNS) toxicity manifesting as metronidazole-induced encephalopathy (MIE).

METHODS

Case report.

RESULTS

A 65-year-old woman with hepatitis B cirrhosis (Child-Pugh class C, MELD 21) developed progressive encephalopathy to GCS 4 during a 3-week course of metronidazole for cholecystitis. Initial MRI was consistent with CNS metronidazole toxicity, with symmetrical T2 hyperintensity and generally restricted diffusion in bilateral dentate nuclei, corpus callosum, midbrain, superior cerebellar peduncles, internal capsules, and cerebral white matter. Laboratory values did not demonstrate significant electrolyte shifts, and continuous EEG was without seizure. High-dose thiamine was empirically administered. Lumbar puncture was not performed due to coagulopathy and thrombocytopenia. Despite discontinuation of metronidazole and keeping ammonia levels near normal, the patient did not improve. MRI was repeated 1 week after discontinuation of metronidazole. Although there was decreased DWI hyperintensity in the dentate nuclei, diffuse T2 hyperintensity persisted and even progressed in the brainstem, basal ganglia, and subcortical white matter. Petechial hemorrhages developed in bilateral corticospinal tracts and subcortical white matter. T1 hypointensity appeared in the corpus callosum. She was transitioned to comfort measures only and died 12 days later.

CONCLUSION

MIE is an uncommon adverse effect of treatment with metronidazole that characteristically affects the dentate nuclei but may also involve the brainstem, corpus callosum, subcortical white matter, and basal ganglia. While the clinical symptoms and neuroimaging changes are usually reversible, persistent encephalopathy with poor outcome may occur.

Reversible Posterior Leukoencephalopathy Syndrome Associated with Treatment for Acute Exacerbation of Ulcerative Colitis

Reversible posterior leukoencephalopathy syndrome (RPLS) is a clinical syndrome of varying etiologies with similar neuroimaging findings. This is a case report of a 25-year-old woman who developed typical, neurological symptoms and magnetic resonance imaging abnormalities after treatment for the acute exacerbation of ulcerative colitis (UC), which included blood transfusion, the systemic administration of prednisolone, and the administration of metronidazole. It has been reported that these treatments may contribute to the development of RPLS. RPLS should therefore be considered in the differential diagnosis of UC patients who exhibit impaired consciousness, seizures or visual deficits during treatment. We report a rare case of RPLS in a patient with UC.

[Reversible changes on MR images in a patient with metronidazole-induced encephalopathy]

A 66-year-old woman was diagnosed with a brain abscess. The abscess was drained by sterotactic catheter insertion. She was administered metronidazole at a dose of 2 g/day. On the 30th day of treatment, she had nausea that gradually progressed. On the 45th day, she developed a disturbance of consciousness and was admitted to our department. She was in stuporous state, and had slight vestibular and cerebellar dysfunctions. Diffusion-weighted and FLAIR brain MR images showed bilateral symmetrical high signals in the splenium of the corpus callosum (SCC), cerebellar dentate nucleus, and inferior colliculus. The apparent diffusion coefficient (ADC) map was reduced in the SCC, but not in the other locations. The peak of lactate on MR spectroscopy was increased in the SCC. The clinical presentation and image changes of the patient were thought to be most consistent with metronidazole toxicity. Metronidazole was discontinued, and her condition improved rapidly. She was discharged 14 days later. The lesions in her cerebellar dentate nucleus and inferior colliculus, suspected to be vasogenic edema, had disappeared 5 to 10 days later, whereas the lesion in the SCC, which gradually diminishing, could still be faintly detected 40 days later, which corresponded to our suspicion of cytotoxic edema.