Cerebellar Hippocampal and Basal Nuclei Transient Edema with Restricted diffusion (CHANTER) Syndrome.

Case Description:

A 24-year-old female patient with PMH of schizoaffective disorder and opioid use disorder was admitted to emergency department for altered mental status where she initially received Narcan. Computed tomogram (CT) head showed diminished attenuation in the right occipital/posterior parietal lobe, basal ganglia, thalami, and cerebellar hemispheres likely representing acute ischemic change, resulting in mass effect upon the fourth ventricle and quadrigeminal cistern with resultant mild hydrocephalus. Due to ischemic changes, a stroke code was called with NIH stroke score 14; no thrombolytics were given since the patient was outside the window; besides, CT angiogram/CT perfusion brain findings were negative for occlusion/stenosis of blood vessel or perfusion mismatch. Patient underwent emergent external ventricular drain (EVD) placement following CT findings for cerebral edema. The patient’s urine toxicology was positive for cocaine while the infectious work up, metabolic panel and echocardiogram were unremarkable. Patient’s video electroencephalogram (VEEG) showed no seizure like activity.

Discussions: Distinct radiological findings, history of opioid use and a positive urine toxicology for cocaine supported the diagnosis of CHANTER syndrome. The patient was discharged to acute rehabilitation with improvement in alertness but with psychomotor slowing, cognitive and linguistic deficits. Ischemic stroke, hypoxic ischemic encephalopathy (HIE), heroin associated spongiform leukoencephalopathy (HASL), posterior reversible encephalopathy syndrome (PRES) may top the differential diagnoses in patients with altered mental status, however radiological findings differentiate CHANTER syndrome from ischemia owing to lack of vascular occlusion as evident on angiogram. Also, unlike HIE, HASL and PRES that affect white matter, CHANTER syndrome affects gray matter.



Conclusions: A rare but emerging syndrome with distinct radiological pattern should be a part of differential diagnosis for altered mental status in patients with history of opioid use.