Toxic Leukoencephalopathies, Including Drug, Medication, Environmental, and Radiation-Induced Encephalopathic Syndromes

An 82-year-old man with ataxia and dysarthria

“…Clinical features may include cerebellar dysfunction, altered mental status and seizures. 4,6 Our patient presented with symptoms of cerebellar dysfunction. A systematic review of case reports and case series involving 64 patients showed that 75% of affected patients had cerebellar dysfunction, 33% had altered mental status and 13% had seizures; 17% of patients had both cerebellar dysfunction and altered mental status; and one patient presented with all three manifestations.…”

“…2,3 The splenium of the corpus callosum, periaqueductal grey matter and dorsal brainstem are often also involved. 3,4 Less commonly, there is abnormality in the cerebral hemispheric white matter or basal ganglia. 4 This patient had received metronidazole for 11 weeks for his foot ulcer, with a total cumulative dose of more than 80 g.…”

“…3,4 Less commonly, there is abnormality in the cerebral hemispheric white matter or basal ganglia. 4 This patient had received metronidazole for 11 weeks for his foot ulcer, with a total cumulative dose of more than 80 g.…”

“…3 Experimental models show that intermediate metabolites of metronidazole can bind neuronal RNA, resulting in reversible axonal edema, as well as possibly modulating the expression of γ-aminobutyric acid. 3,4,6,7 Idiosyncratic drug reactions In general, idiosyncratic drug reactions are unpredictable adverse effects that cannot be explained based on the pharmacology of a drug. 8,9 Although the exact mechanism is still incompletely understood, these events are often believed to result from reactive metabolites of a drug and not the drug itself.…”

Susceptibility-weighted imaging in stroke-like migraine attacks after radiation therapy syndrome

“…Previously, it was believed that SMART syndrome is entirely reversible; however, Black et al have reported that it may result in permanent neurologic or imaging sequelae [1][2][3][4][5]. While the late-delayed effects of radiation damage are well described, including vascular abnormalities and endothelial injury, other mechanisms may also contribute, such as impaired ion channel reactivity and autoregulation; such alternative hypotheses have been proposed as possible contributors to the pathophysiology of this syndrome [5,22,23]. A younger age at the time of irradiation, male gender, the addition of chemotherapy, and even genetic susceptibility may predispose patients to develop SMART syndrome [6].…”