Neuroscan: Surface Electromyography (SEMG)

The St Luke’s Movement Disorders Center offers a painless, cutting-edge alternative in assessing movement disorders—the Neuroscan. The Neuroscan is a machine that utilizes surface electromyography (SEMG) technique to characterize muscle activity using surface electrodes placed on the skin overlying muscle. It allows evaluation of multiple muscles simultaneously and without pain. St Luke’s is the first medical center to make this new technology available in the Philippines.

Neurophysiologic SEMG data collected by the Neuroscan can help diagnose movement disorders. Many tremor disorders are characterized by distinct muscle activity patterns. The SEMG data collected is used to classify the tremor based on its frequency, amplitude of muscle activity and its presence at rest, with posture or with activity.

Other potentially important clinical applications of SEMG include differentiating tremor from myoclonus, spasmodic torticollis from other head tremors, and primary writing tremor from writer’s cramp, as well as identifying propriospinal myoclonus and psychogenic movement disorders.

A Neuroscan examination normally takes about 1 to 1 ½ hours. It starts with a clinical assessment of the patient by the movement disorders specialist who then decides which appropriate muscles to record. Usually, surface electrodes are pasted on the skin overlying pairs of antagonistic muscle, i.e. muscles that work opposite each other like wrist flexors and extensors. Neurophysiologic data are then recorded at rest, with posture, and with action. Standard activity such as writing or drawing spirals is augmented by specific activity that a patient, by experience, knows will activate an involuntary movement.