Hippocampal involvement due to heroin inhalation--"chasing the dragon".

Toxic leukoencephalopathy occurs as a result of exposure to wide variety of agents. Inhalation of heroin or its vapours produces a distinct syndrome with characteristic findings on MR imaging. We report a case of heroin vapour abuse (chasing the dragon) who presented with altered sensorium. MRI of the brain showed symmetrical T2 hyperintensities over the cerebellum and hippocampi. The patient gradually improved and made good recovery but developed spasticity of all the limbs due to delayed involvement of bilateral basal ganglia. This is the first report of bilateral hippocampal involvement in a patient abusing heroin vapour.