Posterior Reversible Encephalopathy Syndrome is hypothesized to be caused by severe hypertension disrupting brain blood flow, autoregulation and endothelial function. It typically presents as altered mental status, headaches, & seizures. This case highlights association of ICIs with PRES in the absence of significant hypertension.

CASE PRESENTATION:

A 73-year-old right-handed woman with recently diagnosed renal cell carcinoma s/p nephrectomy presented with generalized tonic clonic activity, urinary incontinence followed by unresponsiveness, right gaze deviation, & left-sided hemiparesis. Three weeks prior to that, she was started on nivolumab and ipilimumab.  CT Brain & CTA were unremarkable. The patient received 1.5 g levetiracetam & required emergent intubation for failure to protect her airway. Her initial BP was 157/69 mmHg & remained below 160/80 mmHg during admission. Her MRI brain w/o contrast showed flair hyperintensities on bilateral parietal and occipital areas suggestive of PRES. CSF analysis was unremarkable except for elevated protein (86mg/dl). Meningitis (CSF) & serum autoimmune panels were negative. She received IV steroids followed by tapering dose of oral steroids.  Improvement in neurological function was noted over a week including partial resolution of imaging changes on a repeat MRI Brain. She was discharged with improving cognitive & neurological function on tapering dose of steroids & maintenance levetiracetam.

DISCUSSION:

Despite important clinical benefits, ICIs are associated with a unique spectrum of side effects termed immune-related adverse events (irAes) & can affect multiple organ systems. The incidence of neurological irAes is about 1-5% but the real incidence is likely higher. Most reported neurological irAes include encephalitis/meningitis, myasthenia gravis & peripheral neuropathy.

Our patient presented with a rare case of PRES due to immune check point inhibitors. This potentially serious complication needs to be recognized as ICIs are now more frequently used as immunotherapeutic agents.