Metronidazole Induced Encephalopathy Mimicking an Acute Ischemic Stroke Event

Abstract

Metronidazole induced encephalopathy (MIE), an encephalopathy brought by an antibiotic, is characterized with cerebellar dysfunction, altered mental status and extrapyramidal symptoms. MIE can result in an acute manifestation, but MIE has not been reported as a stroke mimic. An 86-year-old patient undergoing metronidazole therapy for Clostridium difficile enteritis presented to our hospital with sudden disoriented status and motor weakness of the left extremities. Computed tomography (CT) was unrevealing of intracranial hemorrhagic change, and CT angiography did not show any apparent major occlusion or stenosis of the intracranial vessels. However, CT perfusion (CTP) revealed a decrease in peripheral blood flow in the right cerebral hemisphere, and tissue plasminogen activator was administrated for a possible acute ischemic stroke. The findings of follow-up magnetic resonance imaging (MRI) were typical for MIE, revealing areas of hyperintensity on fluid attenuated inversion recovery (FLAIR) signal intensity in the dentate nuclei, the splenium of the corpus callosum, and in the dorsal midbrain. The degree of hyperintensity was stronger in the left dentate nucleus than in the right left dentate on FLAIR and the apparent diffusion coefficient map. The asymmetric findings of the left dentate nucleus on MRI were considered to be responsible for the clinical symptoms and the findings of CTP. We report a rare case of MIE mimicking an acute ischemic stroke, and hypothesize the relationship between the findings of CTP and that of MRI based on the anatomical connection of the dentate nucleus and the cerebral hemisphere.

A potential new role for ASL perfusion imaging: Diagnosis of metronidazole induced encephalopathy – Two companion cases

“…[10] , [11] , [18] Alternatively, Takada et al also postulated that these findings may be related to inflammation or cytotoxic edema. [19] Takada et al also describe decreased cerebral blood flow in CT perfusion in a cerebral hemisphere mimicking stroke, however, they did not note any perfusion abnormality within the dentate nuclei or splenium as seen in our case series. [19] Given the increased ASL signal in our reported cases, these findings are thought to represent hyperperfusion which could be related to underlying edema or secondary inflammatory factors potentially due to axonal swelling from oxygen radicals.…”

“…Six weeks after the initial presentation, the patient acutely deteriorated, presenting with altered mental status and hypotension with systolic blood pressures in the 70s. His vital signs demonstrated tachycardia and tachypnea with an elevated white blood cell count of 23.1 × 10 9 /l, decreased hemoglobin (Hb) of 8.0 g/dl, and borderline ammonia level at 35 μmol/l (ref [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25] 35). Remainder of the labs, including sodium and magnesium levels, were within normal range.…”

Acute metronidazole-induced neurotoxicity: an update on MRI findings

“…The authors hypothesised that the right cerebral hemisphere perfusion changes may relate to the presenting symptoms of left sided weakness, which mimicked an acute stroke, and might be a remote effect of left dentate nucleus toxicity from metronidazole. 16 The clinical consequences of lesions in the other areas that were affected in the present cohort is also uncertain. For example, whether basal ganglia and subcortical white matter lesions contribute to motor symptoms directly or are clinically silent is not yet known.…”

Clinical application of brain perfusion imaging in detecting stroke mimics: A review

“…In contrast to stroke, perfusion abnormalities in this patient were diffuse, not respecting the boundaries of vascular territories. 92 However, Yedavalli and Lanzman detected bilaterally increased signal restricted to the dentate nuclei and splenium on ASL sequences. 93 Characteristic MRI findings such as hyperintensity of the dentate nucleus and splenium of the corpus callosum on fluid-attenuated inversion recovery images, seen in both studies, can distinguish this encephalopathy from acute ischemic stroke.…”