J-LSMS 2024 | Abstracts | 2024

AUTOIMMUNE ENCEPHALITIS SECONDARY TO EMBROLIZUMAB IN A PATIENT WITH NON-SMALL CELL LUNG CANCER Brooke McVaney DO, Nali Gillespi MD, Ross McCarron MD; Department of Medicine, LSU Health New Orleans, New Orleans, LA.

Introduction: Immune checkpoint inhibitors (ICPi’s) are immunotherapies that have improved lung cancer treatment and overall survival rates. Pembrolizumab is an antibody that targets the PD-1 receptor of lymphocytes, therefore allowing the immune system to destroy cancer cells. By inhibiting the PD-1 receptor immune checkpoint, patients are placed at increased risk for immune- mediated adverse reactions, including encephalitis. Case: A 66-year-old male with a 14-month history of stage IV adenocarcinoma of the lung previously treated with carboplatin/pemetrexed/ pembrolizumab and now on maintenance pemetrexed/pembrolizumab presented with a 1-day history of altered mental status. One week prior to presentation the patient began to experience fatigue, decreased appetite and progressive confusion. At the time of admission, he was febrile, hypertensive and tachycardic. The patient was disoriented on exam. Labs were notable for WBC 13.87K/uL and urine drug screen positive for opioids. Lactate, procalcitonin, ammonia and urinalysis were normal. Lumbar puncture results were normal. Cerebrospinal fluid (CSF) studies were negative for JC virus, histoplasma antibody, HSV, VDRL, CMV, VZV, cryptococcus

and EBV. CSF and blood cultures finalized with no growth. CSF paraneoplastic autoantibody panel was negative. Glial fibrillary acidic protein (GFAP) cell-based assay of the CSF was positive with a titer of 1:128. Magnetic resonance imaging of the brain demonstrated increased signal abnormality within the basal ganglia and thalamus bilaterally, consistent with encephalitis/meningitis. EEG was negative for seizure. The patient was placed on broad spectrum antimicrobial coverage with vancomycin, cefepime and acyclovir hospital days 1-6 with no improvement in mental status. He was placed on solumedrol 1 gram every 24 hours during hospital days 5-7 for treatment of a suspected immune-related adverse event secondary to pembrolizumab with subsequent marked improvement in mental status. At three months post-discharge the patient was noted to be back at his baseline functional status. Discussion: We report a case of autoimmune encephalitis secondary to pembrolizumab use. This case demonstrates that with increasing use of ICPi’s, autoimmune encephalitis should be included in the differential for encephalopathy in patients treated with immunotherapy agents.

PARKINSONISM-HYPERPYREXIA SYNDROME: A CASE REPORT EMPHASIZING EARLY RECOGNITION AND MANAGEMENT IN PARKINSON'S DISEASE David Nguyen BS, Hannah Rader MD, Brian Coe MD, Maren Bell MD, Ross McCarron MD; Department of Medicine, LSU Health New Orleans, New Orleans, LA.

Introduction: Parkinsonism-hyperpyrexia syndrome (PHS) is an uncommon but severe clinical entity with diverse symptoms, including muscular stiffness, hyperthermia, autonomic dysfunction, respiratory distress, and altered consciousness. PHS can be triggered by the abrupt cessation of dopaminergic agents in Parkinson's disease patients. Case: A 67-year-old man with Parkinson's disease and depression presented with confusion and generalized weakness. He was on multiple medications, but the patient’s wife reported that he had not been taking his Parkinson’s medications for the last three days. The patient presented with tachycardia, a

temperature of 102.1 degrees Fahrenheit and an oxygen saturation of 94% on room air. Labs revealed hyponatremia, metabolic acidosis, and a significantly elevated creatine phosphokinase (CPK) level. Additionally, the lactate, partial pressure of carbon dioxide, and pH were outside the normal range. Chest radiography and a head computed tomography scan were unrevealing. The patient's clinical condition deteriorated, leading to the development of hypertension and worsening altered mental status with temperatures peaking at 103 degrees Fahrenheit. Empiric antibiotics were initiated after cultures were obtained. Supportive treatment measures for his hyperthermia and hypertensive crisis were 25

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