Acute disseminated encephalomyelitis; Literature citation.  Case reference number US-BN-2023-001405 is a literature case report, title as stated above, identified on 16-Aug-2023 and concerns a 30-year-old male patient.  On unspecified dates, the patient was vaccinated with the first and second dose of Jynneos vaccine (batch number: unknown), at an unknown dose, route or site of administration, for protection against monkeypox.  On unspecified date, the patient without pertinent past medical history presented with persistent headache, coordination difficulties, aphasia, and personality changes presented to his local emergency department for workup and evaluation. Symptoms started two to three weeks after receiving the second dose of the Jynnesos vaccine. Magnetic resonance imaging (MRI) of brain showed diffuse small bilateral ischemic lesions in the corona radiata and posterior corpus callosum and the patient was diagnosed with multifocal strokes with negative workup for common stroke etiology. The patient was started on aspirin, clopidogrel, and high intensity statin therapy. After a seven-day hospitalization, the patient presented to acute inpatient rehabilitation. On admission the patient presented with three out of five strength in all extremities, was arousable to loud voice and touch, verbalized single words and short phrases, followed grasp-and-release commands 50 percent of the time, tolerated moist ground solids and nectar liquids, was dependent for all activities of daily living (ADL) and instrumental ADLs, and had a Glasgow Coma Scale of 12. Over the following five days the patient steadily declined with decreased arousal, decreased verbalization, and worsened dysphagia requiring nil per os (NPO) status. Examination demonstrated an inability to follow any commands and two out of five strength in all extremities, with stable vitals.   Computerised tomography (CT) of head and brain magnetic resonance imaging (MRI) were ordered to rule out repeat stroke or hemorrhagic conversion. Given the patient had no known risk factors for stroke - no history of cardiovascular disease, diabetes, preceding infections, sedentary lifestyle, family history, or confirmed drug use, hemorrhagic conversion was higher on the differential. Complete blood count (CBC), complete metabolic panel (CMP) and urinalysis (UA) were ordered to evaluate for infectious or metabolic etiologies.   Initial results from the CMP, CBC and UA were unremarkable for severe electrolyte abnormalities, obvious infectious processes, or other processes that would explain clinical presentation. Repeat CT head showed multifocal supratentorial and infratentorial hypoattenuating lesions which matched initial CT head from the outside hospital. Repeat MRI brain showed diffuse cerebral edema with supratentorial and infratentorial ischemic lesions; these findings were suggestive of a vasculitis, encephalomyelopathies, or a hypoxic ischemic encephalopathy with potential superimposed embolic phenomena.  The patient was transferred to an acute care hospital, admitted to neurology service, and started on empiric broad spectrum antibiotics. Additional workup included cerebrospinal fluid (CSF) studies and multiple specialized send-out labs for autoimmune testing, which included oligoclonal bands. Lumbar puncture showed significantly elevated protein (292 mg/dL), normal glucose, and normal lactate dehydrogenase. Markers for Covid, herpes simplex virus (HSV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), human immunodeficiency virus (HIV), John Cunningham virus (JCV) and tickborne illnesses were negative. Antineutrophil cytoplasmic antibody (ANCA), rheumatoid factor (RF), antinuclear antibody (ANA), SS-A and SS-B antibodies, neuromyelitis optica, lupus hypercoagulable, prothrombin gene mutation, and factor V Leiden were also negative.  After a thorough exam and workup, clinical picture was highly suspicious for acute disseminated encephalomyelitis (ADEM) which was a diagnosis of exclusion. Neurology opined that the strokes found on initial imaging prior to decline were also evidence of ADEM, rather than isolated strokes. Hematology was consulted and plasmapheresis (PLEX) was initiated along with a steroid taper. After the first round of PLEX, the patient became more mobile, able to follow simple commands and attempted vocalization. Over the course of twenty-three-day hospitalization, the patient received a total of five rounds of PLEX with improvements in function and mental status after each round and including a notable advance from NPO status to a puree diet and nectar liquids. The patient was then readmitted for ongoing rehabilitation.  The patient's functional gains continued upon readmission to inpatient rehab, where the patient was more alert, able to follow simple commands and continued to exhibit speech improvements and diet advances. On day 21 of thirty-four-day stay the patient was started on amantadine for inattention with improvements noted soon after initiation, this was continued after discharge. Upon discharge, the patient was eating a regular diet with supervision, required moderate assistance with dressing, was able to ambulate 40ft with a walker with maximal assistance with a wheelchair follow and could communicate in short sentences.  At the time of the initial report, the patient was recovering from the event of acute disseminated encephalomyelitis.  The reporter did not provide seriousness assessment for the event of acute disseminated encephalomyelitis, however the event was assessed as serious due to seriousness criteria of hospitalization and medical significance. The reporter assessed the event of acute disseminated encephalomyelitis as related to Jynneos vaccine, reported as suspected to have triggered the event due to recent monkeypox vaccination, global decline in patient functioning and lack of other potential etiologies.; Reporter's Comments: A 30-year-old male patient was hospitalized due to acute disseminated encephalomyelitis (ADEM), 2-3 weeks after vaccination against mpox with the second dose of Jynneos (given via unknown route and at unknown dose). Patient's symptoms included headache, coordination difficulties, aphasia, personality changes. Brain MRI showed bilateral ischemic lesions in corona radiata and posterior corpus callosum, initially interpreted as multifocal strokes with negative workup for common stroke etiology. Initial treatment with aspirin, clopidogrel and statins. After the seventh day of hospitalization, the patient had a decline in verbalization and arousal. Dysphagia worsened which required status. Patient was unable to follow commands. CMP, CBC and UA were unremarkable. EBV, HIV, CMV, JCV, HSV tests were negative. Repeat head CT showed multifocal supratentorial and infratentorial hypoattenuating lesions (matching the earlier findings). Repeat brain MR showed diffuse cerebral edema with supratentorial. Lumbar puncture showed elevated protein. Based on this data, physicians rejected the diagnosis of multifocal strokes, and diagnosed the patient with ADEM. Plasmapheresis was started. Functionality, mental status and speech improved. Amantadine was given. ADEM is unlisted and unexpected per the agency for Jynneos. The patient had no pertinent past medical history. Considering that multiple alternative etiologies were rejected, the event is conservatively assessed as related to Jynneos. The case is serious due to hospitalization and medical significance.; Sender's Comments: A 30-year-old male patient was hospitalized due to acute disseminated encephalomyelitis (ADEM), 2-3 weeks after vaccination against mpox with the second dose of Jynneos (given via unknown route and at unknown dose). Patient's symptoms included headache, coordination difficulties, aphasia, personality changes. Brain MRI showed bilateral ischemic lesions in corona radiata and posterior corpus callosum, initially interpreted as multifocal strokes with negative workup for common stroke etiology. Initial treatment with aspirin, clopidogrel and statins. After the seventh day of hospitalization, the patient had a decline in verbalization and arousal. Dysphagia worsened which required status. Patient was unable to follow commands. CMP, CBC and UA were unremarkable. EBV, HIV, CMV, JCV, HSV tests were negative. Repeat head CT showed multifocal supratentorial and infratentorial hypoattenuating lesions (matching the earlier findings). Repeat brain MR showed diffuse cerebral edema with supratentorial. Lumbar puncture showed elevated protein. Based on this data, physicians rejected the diagnosis of multifocal strokes, and diagnosed the patient with ADEM. Plasmapheresis was started. Functionality, mental status and speech improved. Amantadine was given. ADEM is unlisted and unexpected per the agency for Jynneos. The patient had no pertinent past medical history. Considering that multiple alternative etiologies were rejected, the event is conservatively assessed as related to Jynneos. The case is serious due to hospitalization and medical significance.