Electrophysiologic testing in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease in which cell loss from the midbrain substantia nigra reduces levels of the neurotransmitter dopamine. Symptoms include tremor of the hands while at rest, slowed movements, stooped posture, tendency to fall, muscular rigidity, and small handwriting. At present there is no cure for PD. Medications, neurosurgical procedures, and nonpharmacologic interventions are quite effective in controlling symptoms. While electrophysiology has a limited role at present in the diagnosis of PD, certain abnormalities are revealed on testing. These include mild background slowing of the EEG, delayed movement- related mu dropout, low amplitude sensory and motor event-related cortical potentials, and subtle autonomic impairments. These abnormalities likely reflect the neural processing deficits that cause the characteristic symptom complex.