A number of causes may be associated with the "lentiform fork" sign in the basal ganglia.

Findings on imaging studies:

(1) symmetrical basal ganglia hypodensities

(2) "fork sign" on T2-weighted FLAIR images (hyperintense signals of the external and posterior internal capsules, with confluence at the posterior putamen)

(3) later images may show areas of necrosis in the putamen


Conditions associated with the lentiform fork sign:

(1) uremic encephalopathy

(2) metabolic acidosis, including genetic acidopathies and methanol intoxication

(3) methamphetamine abuse

(4) atypical posterior reversible encephalopathy syndrome

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