Spinal Disorders: Fundamentals of Diagnosis and Treatment Part 35. Spinal disorders are among the most common medical conditions with significant impact on health related quality of life, use of health care resources and socio-economic costs. Spinal surgery is still one of the fastest growing areas in clinical medicine. | 322 Section Patient Assessment Figure 2. Electromyography Spontaneous muscle activity is recorded at the target muscles. stration of neurogenic reinnervation subacute to chronic reinnervation pattern . Limitations The extent of axonal nerve damage and reinnervation is difficult to quantify Spinal disorders with demyelination of motor nerve fibers very slowly evolving neural compression as in benign tumor or stenosis are less assessable by EMG. The extent of axonal nerve damage and reinnervation cannot be easily quantified by EMG. Needle EMG recordings provide some discomfort which can be painful for patients. Nerve Conduction Studies Motor and sensory nerve conduction studies NCS assess the conduction velocity mainly properties provided by the myelination of peripheral nerves and amount of impulse transmission axonal transport capacity . These parameters distinguish between a primarily axonal and or demyelinating neuropathy which cannot be achieved by the clinical examination. Frequently NCS are combined with reflex recordings that provide additional information about changes in nerve conduction. Neurophysiological Investigations Chapter 12 323 Figure 3. Nerve conduction studies The nerve conduction velocity NCV is calculated dividing the distance between the stimulation points by the conduction time between these points. Technique Electrical stimulations Fig. 3 applied along the peripheral nerve branch distal to proximal and recordings by surface electrodes at the distal motor or sensory site allow for the assessment of responses separately and for the calculation of nerve conduction velocities expressed in meters per second by measuring the distance 8 20 . The compound muscle action potential CMAP in millivolts and the sensory action potential in microvolts are calculated to assess the axonal nerve integrity. Indications Nerve conduction studies are primarily indicated in conditions assumed to affect the peripheral nerves damage or disorders of the plexus .
