Course: Lentiform Fork Sign on Magnetic Resonance Imaging After Methamphetamine and Alcohol Misuse
CME Credits: 1.00
Released: 2023-04-17
A 37-year-old man presented to the emergency department with a 3-day history of acute blindness. He had delayed the consultation because of the belief that the symptoms were transient adverse reactions from an overuse of alcohol and drugs. After inquiry, he reported alcohol and methamphetamine use for 3 consecutive nights before onset of visual impairment. He denied drinking home-brewed alcohol or any methanol-containing spirits. The stimulant he had used, crystal methamphetamine, was consumed via inhalation, but he was not a regular user of recreational drugs. There was no open fire or other carbon monoxide source at his home. His vision was severely impaired; he could only see very bright light, and his pupils were dilated and unresponsive. Fundoscopy was unremarkable. He did not report any other symptoms, and remaining neurological examination results were normal. Initial computed tomography of the brain revealed bilateral basal ganglia hypodensities (A). All routine blood and cerebrospinal fluid test results were normal, and his arterial blood gas did not show metabolic acidosis. Urine screen results for misused substances were positive for methamphetamines only. Over the next few days, his vision improved gradually, and he could soon recognize shapes and eventually objects but could not identify red on color testing. Brain magnetic resonance imaging (MRI) could only be arranged after 3 weeks and showed persistence of the basal ganglia abnormalities that affected both lentiform nuclei. The findings are consistent with the radiological pattern of the lentiform fork sign (B).
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