SHM Converge Scientific Abstract ePoster Gallery-What a Stiff Person! Progressive Encephalomyelitis With Rigidity and Myoclonus

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This case report describes a rare neurologic syndrome, progressive encephalomyelitis with rigidity and myoclonus (PERM), in a 72-year-old man with esophageal cancer receiving nivolumab and radiation therapy. PERM is a severe variant of stiff-person syndrome characterized by rigidity, myoclonus, autonomic dysfunction, and exaggerated sensory responses, and is usually associated with autoimmune or paraneoplastic processes.<br /><br />The patient presented with fever, altered mental status, bilateral lower-extremity weakness, spasms, and pain. Exam showed spasticity, hyperreflexia, and myoclonus. Extensive workup was largely unrevealing: CT head was negative, spine MRI did not explain the weakness, brain MRI showed only age-related changes, EEG showed diffuse slowing without seizures, and CSF revealed elevated protein with no pleocytosis. Infectious testing, including meningitis/encephalitis panel and cultures, was negative. Paraneoplastic, autoimmune encephalitis, and anti-GAD antibodies were also negative; GlyR antibody testing was unavailable.<br /><br />Given the clinical picture and exclusion of other causes, PERM was diagnosed, likely triggered by checkpoint inhibitor therapy. The patient was treated with IVIG and intravenous steroids for five days. After two days, his muscle weakness, spasticity, and mental status gradually improved. CSF West Nile IgG was positive but IgM negative, consistent with past infection rather than active disease. He was discharged to inpatient rehabilitation for continued recovery.<br /><br />The discussion emphasizes that PERM is very rare, with fewer than ten published cases, and has been linked to malignancy, infections, and immune triggers. Nivolumab may have initiated an immune cascade leading to this presentation. Because no standardized treatment guidelines exist, immunosuppressive therapies such as IVIG, plasma exchange, and rituximab are used. Clinicians should recognize PERM as a potential checkpoint inhibitor-related autoimmune complication.

Asset Subtitle

Aung Naing

Meta Tag

Author List Aung Naing, FNU Ayesha, Mark Flemmer, Rupinder Bahniwal

Category Clinical Vignettes

Concept Progressive Encephalomyelitis with Rigidity and Myoclonus

Concept Myoclonus

Concept Rigidity

Concept Immune Checkpoint Inhibitor Therapy

Concept Spasticity

Distinguished Non-Finalist

Presenter Organization EVMS at ODU

Presenting Author Aung Naing

Track Adult

Keywords

progressive encephalomyelitis with rigidity and myoclonus

PERM

nivolumab

esophageal cancer

checkpoint inhibitor

autoimmune encephalitis

stiff-person syndrome

myoclonus

intravenous immunoglobulin

paraneoplastic syndrome

Progressive Encephalomyelitis with Rigidity and Myoclonus

Myoclonus

Rigidity

Immune Checkpoint Inhibitor Therapy

Spasticity