Adult-Onset Myoclonus: Comparisons and Contrasts in the Inpatient and Outpatient Settings

Area of Science:

• Neurology
• Movement Disorders

Background:

• Myoclonus is a hyperkinetic movement disorder characterized by rapid, jerky, involuntary movements.
• Etiologies of myoclonus vary significantly between inpatient and outpatient clinical settings.

Purpose of the Study:

• To retrospectively analyze and compare the demographics, etiologies, and outcomes of myoclonus cases in inpatient versus outpatient settings.
• To identify distinct etiological patterns and clinical characteristics of myoclonus based on patient disposition.

Main Methods:

• Retrospective chart review of adult myoclonus cases at New York Presbyterian Brooklyn Methodist Hospital over 10 years.
• Descriptive statistical analysis to compare inpatient and outpatient cohorts regarding demographics, symptom duration, and etiologies.

Main Results:

• 279 inpatients and 85 outpatients were analyzed. Outpatients were younger and had longer symptom durations compared to inpatients.
• Inpatient etiologies predominantly included toxic/drug-induced, metabolic, and hypoxic/ischemic causes.
• Outpatient etiologies more frequently involved neurodegenerative, inflammatory/autoimmune/paraneoplastic, and idiopathic causes. Inflammatory/autoimmune/paraneoplastic etiologies were associated with axial symptoms in outpatients.

Conclusions:

• Significant differences exist in the etiology and symptom duration of myoclonus between inpatient and outpatient settings.
• Neurodegenerative and inflammatory etiologies are more common in outpatients, contrasting with toxic-metabolic and hypoxic-ischemic causes in inpatients.
• Differentiating myoclonus causes by clinical setting may assist clinicians in initial diagnostic probability assessments.