Functional Electromyography

The book introduces the use of provocative maneuvers to widen the scope of application and sharpen the diagnostic acuity of electrodiagnostic studies including nerve conduction velocities (NCV) and electromyogram (EMG). Employing provocative maneuvers in somatosensory, ocular, and brainstem studies is suggested but not detailed. The author suggests the further use of provocative maneuvers in other electrodiagnostics such as somatosensory, visual, and brains stem evoked potential studies.

The electrodiagnostic studies described and suggested here are extensions of the physical examination conducted in many clinical specialties, ranging from internal medicine to neurosurgery to chiropractic and other types of body workers. These studies are central to the work of physiatrists, neurologists, orthopedic surgeons and specialists in pain management. The techniques extend the reach of EMG to conditions that were difficult to diagnose by any means before. In addition, the book provides direction to adapt its methods to cases beyond those it discusses.

The book presents three well-documented examples of functional EMG: the changes in electrophysiological parameters with provocative maneuvers help make diagnosis of piriformis syndrome that is otherwise considered a "diagnosis of exclusion" by many physicians, yet can be proven to occur frequently in respectably large sample populations.

Neurological thoracic outlet syndrome is another diagnosis that is even less accessible. Although its incidence and prevalence are less thoroughly documented, it is important both to identify the entity and to have a definitive means to rule it out, especially in referred or neurological upper extremity pain of non-cervical origin.

Third, the distinction between foraminal narrowing due to disc herniations and spinal stenosis is often difficult in the many cases in which both are present. The clinical question often revolves around which of the two conditions is the major pain generator. Studies in physical therapy, cadaveric and otherwise, find that extension is beneficial in treating disc herniation, yet it narrows the stenotic spine up to 63% further. Conversely, while flexion is beneficial for spinal stenosis, it can dangerously extend discal herniations. A safe. replicable and reversible maneuver can distinguish which of these two conditions is more likely to contribute the majority of the patient's symptoms.

The book then goes on to suggest a safe and scientific method for determining other functional maneuvers of value to the electromyographer and suggests means of validating one-time measures that may benefit the electromyographer in diverse clinical situations that are neither common nor predictable. Some of these are as obvious as comparison with the unaffected limb in a carpal tunnel syndrome that only shows up in the flexed wrist; others require the use of standard deviations derived for other purposes, and depend upon the discretion of the clinician as well as the particular case.