(Kiosk 3) Altered Mental Status After Mpox Vaccination: A Case Report

Case Diagnosis: Acute disseminated encephalomyelitis after receiving 2nd dose of Jynneox vaccine for primary prevention of mpox.

Case Description or Program Description: The patient received the Jynneos vaccine for primary protection against mpox and 2-3 weeks after receiving the 2nd dose he presented to an acute hospital with persistent headaches, coordination difficulties, aphasia, and personality changes. MRI brain showed multiple small bilateral lesions in corona radiata and posterior corpus callosum and he was diagnosed with multifocal strokes with negative workup for stroke etiology. He was discharged to our IRF after a 1-week hospital stay. On admission, was arousable to loud voice and touch, verbalized single words and short phrases, followed simple commands 50% of the time and was on a pureed / nectar diet. Over the following 5 days at our IRF he had notable declines in arousal, decreased verbalization, worsening dysphagia, and global weakness. Initial workup consisted of CBC, CMP, infectious workup, and CT head and was largely unremarkable. Patient continued to decline and was transferred to the regional acute care hospital. Neurology was consulted, MRI brain showed diffuse cerebral edema with supratentorial and infratentorial lesions consistent with an encephalomyelopathy. Lumbar puncture showed wildly elevated protein, normal glucose, normal lactate dehydrogenase, negative oligoclonal bands. Patient was diagnosed with acute disseminated encephalomyelitis (ADEM). He received x5 rounds of PLEX therapy and steroid taper and had notable improvements in functioning following each treatment.

Setting: Inpatient Rehabilitation Hospital (IRF)

Assessment/Results: 3 weeks later patient returned to IRF and was advanced to a regular diet, had notable improvement in strength, cognition, alertness, and command following.

Discussion (relevance): This is the first reported case, to our knowledge, of ADEM felt to be due to mpox vaccination.

Conclusions: As mpox vaccination continues, additional cases of post-vaccination ADEM may be reported in IRF settings. Increased clinician awareness of ADEM after mpox infection or vaccination is essential for proper diagnosis, evaluation, management, and outcome prognostication.