Specific Imaging Findings

Initial CT and MRI studies in patients following methanol ingestion may be normal. CT and MRI performed at least 24 h after ingestion demonstrate characteristic bilateral necrosis of the putamina, which appear hypodense and edematous on CT and hyperintense on T2-weighted MR images. Hemorrhagic foci can also be seen within the putaminal lesions and other basal ganglia may be involved. Contrast-enhanced MR images may demonstrate peripheral enhancement of putaminal and subcortical lesions in the acute phase of injury. Optic nerve MR imaging reveals nonspecific T2 hyperintensity. Other findings seen in patients who survive for several days are non-enhancing areas of necrosis within the peripheral white matter, with sparing of the subcortical white matter U-fibers.

Pertinent Clinical Information

Symptoms of methanol intoxication usually begin after a 12- to 24-h latent period following ingestion. Patients typically experience visual disturbances, including decrease in visual acuity, visual field defects, color blindness, hyperemia of the optic discs, and peripapillary nerve fiber edema, and neurologic symptoms, including weakness, headache, and dizziness. Gastrointestinal complaints (pain, nausea, and vomiting) are also common. With larger consumed doses, seizures, stupor, and coma may occur. Laboratory evaluations will reveal a severe metabolic acidosis. Patients who survive methanol poisoning may have permanent blindness or irreversible neurologic impairments.