Progressive Encephalomyelitis With Rigidity and Myoclonus With Glycine Receptor Antibodies: Clinical Features and...

Area of Science:

• Neuroimmunology
• Neurology
• Autoimmune Encephalitis

Background:

• Progressive encephalomyelitis with rigidity and myoclonus (PERM) is a rare neurological disorder.
• Glycine receptor (GlyR) antibodies are implicated in a subset of PERM cases.
• PERM is often categorized under stiff-person spectrum disorders (SPSDs).

Purpose of the Study:

• To delineate the clinical characteristics of GlyR antibody-mediated PERM.
• To evaluate the long-term prognosis and outcomes for patients with GlyR antibody-PERM.
• To determine if GlyR antibody-PERM should be distinguished from other SPSDs.

Main Methods:

• Retrospective analysis of 22 patients diagnosed with GlyR antibody-PERM in the authors' laboratory.
• Systematic literature review of 19 additional PERM patients with sufficient clinical data and follow-up.
• Assessment of neurological disability using the modified Rankin Scale (mRS) and tracking of relapses.

Main Results:

• Forty-one patients (88% male, median age 58) were identified with GlyR antibody-PERM.
• Predominant symptoms included brainstem dysfunction (56%), muscle rigidity/myoclonus (22%), and sensory disturbances (17%).
• The disease was severe (median nadir mRS 5), with a mortality rate of 27% (11/41); age and ICU admission predicted poor outcomes.

Conclusions:

• GlyR antibody-PERM is a severe, rapidly progressive neurological disease with a distinct clinical profile, particularly frequent brainstem involvement.
• The findings support classifying GlyR antibody-PERM separately from other SPSDs, which are typically chronic and GAD-antibody associated.
• Despite severity, immunotherapy led to good functional recovery (mRS <3) in 70% of survivors.