ACUTE ENCEPHALOPATHY SECONDARY TO SERONEGATIVE LIMBIC ENCEPHALITIS IN THE ICU: OUT OF SIGHT OUT OF MIND

TOPIC: Critical Care TYPE: Fellow Case Reports INTRODUCTION: Seronegative Limbic encephalitis (SNLE) is a rare condition that presents with cognitive impairment, personality changes, memory loss, and seizures. It results from either an idiopathic or neoplasm mediated autoimmune processes leading to direct neuronal damage. We present a rare case of SNLE that significantly improved after early recognition and aggressive plasma exchange therapy. CASE PRESENTATION: A 75-year-old woman with history of systemic lupus erythematosus, CKD, hypertension, presented with 14 day history of new-onset progressively worsening behavioral changes manifested by irritability, psychosis, confusion, delirium and elevated blood pressures ranging from 200-250 mm Hg. On admission, patient was extremely delirious and was intubated for airway protection. Workup showed Hb 9.8, BUN 62, Cr 3.15, and ESR >145. CT head was negative for abnormalities and MRI brain showed small vessel disease with old microhemorrhages but no acute pathology. Patient was started on antibiotics and acyclovir for suspicion of central nervous system infection, hypertension was managed with intravenous nicardipine. CSF revealed mildly elevated total protein of 59 mg/dL and white cell count of 3, otherwise normal. Blood cultures, CSF cultures, HSV I/II, West Nile, COVID-19 and prolonged video EEG remained unremarkable. Lupus cerebritis was ruled out by rheumatology given stable levels of C3/C4. Patient developed generalized hyperekplexia with repetitive clonus-like movements of all extremities that resolved spontaneously shortly after discontinuation of the external stimuli. Given her the clinical presentation, hyperekplexia on exam and negative work-up, limbic encephalitis was suspected. She was started on IV steroids and plasma exchange therapy with significant improvement in mental status. Paraneoplastic panel came negative. A CT scan of abdomen/pelvis showed an adrenal mass, however PET was negative for avid malignancy and adrenal gland was hypometabolic. She was discharged with complete neurologic recovery. DISCUSSION: SNLE comprises 10% of all autoimmune encephalitis diagnoses. In our patient due to reports of a previous adrenal mass, initial suspicion was of SNLE secondary to adrenal source was made but after extensive workup the diagnosis of exclusion of autoimmune SNLE was made. Corticosteroids and plasma exchange remain understudied in SNLE yet data suggests at least 50% of patients recover with these interventions. Due to concern of persistent autoimmune injury if SNLE is left untreated/undiagnosed, prompt empiric intervention and simultaneous workup to rule out an underlying occult malignancy may stagnate neurological impairment. CONCLUSIONS: We highly recommend keeping SNLE in the differential of ICU patients with persistent encephalopathy, especially in those with a history of autoimmune disorders. REFERENCE #1: Ahmad SAB, Archer HA, Rice CM, et alSeronegative limbic encephalitis: case report, literature review and proposed treatment algorithmPractical Neurology 2011;11:355-361. DISCLOSURES: No relevant relationships by Ahmad Al-Awwad, source=Web Response No relevant relationships by Sara Habib, source=Web Response No relevant relationships by Huzaifah Salat, source=Web Response