Task Specific Tremor in Parkinson's Disease Responds to Apomorphine.

Background: Task specific tremor (TST) is a poorly understood entity without any standard treatments, that may subsequently develop tremor during additional tasks, later develop postural/kinetic tremor (essential tremor criteria), and later develop Parkinson's disease. The pathophysiology is not understood as it has features of tremor, dystonia, and parkinsonism.

Objectives: To assess response of TST to apomorphine and thus infer pathophysiology.

Diagnostic outcome of muscle biopsy.

Introduction: We reviewed the diagnostic yield of muscle biopsy according to the presence or absence of muscle weakness, hyperCKemia, and electromyogaphic (EMG) abnormalities.

Methods: In a retrospective study, 698 muscle biopsy reports were analyzed. Logistic regression models for myopathy and specific myopathy were fit, and receiver-operating characteristic (ROC) curves were generated to assess prediction accuracy.