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CHANTER syndrome exhibits a typical pattern of clinical and radiologic findings, which include symmetric diffusion restriction in the cerebellum, hippocampus, and basal ganglia, particularly Globus pallidus (GP). Cerebral cortex and subcortical white matter are usually not involved and the distribution of diffusion restriction does not follow a specific vascular territory, differentiating from other causes. Cerebral edema can progress to cause obstructive hydrocephalous and herniation. Here, we report an instance of CHANTER syndrome where the cause was pain medication rather than substance abuse.  

Case report with electronic medical record review

A 68-year-old woman presented for acute encephalopathy characterized by perseveration, disorientation accompanied by occipital headache and photosensitivity. Of note, she recently started opioid and barbiturate pain medication for chronic back pain. Neurological exam noted disorientation to time and difficulty following complex commands; the rest of the exam, including Kernig's and Brudzinski's, was unremarkable. A CT scan of the head without contrast revealed symmetric hypodensity in the bilateral GP, without signs of hydrocephalus or edema. CTA head/neck was negative for significant vessel stenosis. The drug screen was positive for cannabis and opiates. MRI of the brain with and without contrast noted symmetric diffusion restriction in the GP, hippocampus, and cerebellum. Rest of the workup, including spinal tap, carboxy Hb, and continuous EEG, was unremarkable. She improved clinically with conservative management, and a follow-up MRI of the brain in three months noted resolution of findings.

CHANTERS syndrome is associated with severe edema, hydrocephalus, and herniation; thus, it is critical to recognise characteristic radiological findings regardless of history of illicit drug abuse for prompt recognition. The prognosis is favourable despite the severe presentation, particularly with early treatment.