(8810) Encephalopathy due to Paraneoplastic Syndrome in Newly Diagnosed Malignancy

Introduction: There is a broad differential for encephalopathy in the ICU. This case describes a patient with nonclassical neurological paraneoplastic syndrome as the most likely etiology of encephalopathy with a new diagnosis of lung cancer after video-assisted thoracoscopic surgery (VATS) with pleural decortication.

Description: A 60 year-old male with end-stage renal disease and congestive heart failure with history of recurrent pleural effusions presented to the emergency department with complaints of progressively worsening dyspnea. Historically, patient had two prior thoracenteses in 2019 and 2021 revealing transudative effusions with negative cytology. Imaging revealed loculated right-sided pleural effusion. Thoracentesis on admission revealed exudative effusion. Due to incomplete drainage VATS converted to open thoracotomy with total decortication was performed. A few hours post-operatively, patient required intubation and dialysis upon arrival to ICU due to worsening mental status and metabolic acidosis. Despite minimal sedation for eight days he remained without adequate mental status for extubation. Pathology of the right pleura showed well-differentiated adenocarcinoma. MRI of the brain demonstrated diffuse bilateral cortical predominant restricted diffusion and increased T2/FLAIR signal with diffuse edematous appearance of the cerebellum, bilateral parieto-occipital regions with focal involvement of the posterior right temporal lobe and bilateral mesial temporal lobes. Imaging findings in association with persistently depressed mental status without other metabolic disturbances raised concern for neurologic paraneoplastic syndrome. Cerebral spinal fluid (CSF) analysis revealed glucose of 117 and total protein of 82 with negative gram stain and culture. The basic paraneoplastic returned negative. No further testing was performed as patient’s family elected to withdraw care.

Discussion: There are several well-defined neurological paraneoplastic syndromes, however their presentations vary greatly. In the setting of newly diagnosed or suspected cancer, paraneoplastic syndrome should be considered as a differential diagnosis in patients with altered mental status. Of note, CSF analysis may not always be positive in these cases, however a high degree of clinical suspicion should be maintained.