Needle electromyography

Abstract

Physiologic assessment of diseases of the motor unit from the anterior horn cells to the muscles relies on a combination of needle electromyography (EMG) and nerve conduction studies (NCS). Both require a unique combination of knowledge of peripheral nervous system anatomy, physiology, pathophysiology, diseases, techniques, and electricity is necessary. Successful, high-quality, reproducible EMG depends on the skills of a clinician in patient interaction during the physical insertion and movement of the needle while recording the electrical signals. These must be combined with the skill of analyzing electric signals recorded from muscle by auditory pattern recognition and semiquantitation.1052 This monograph reviews the techniques of needle EMG and waveform analysis and describes the types of EMG waveforms recorded during needle EMG.

Techniques and applications of EMG: measuring motor units from structure to function

“…In standard needle EMG a needle electrode is inserted into the muscle [10], from which electrical activity in multiple motor units (groups of muscle fibres innervated by a single nerve fibre) is sampled. Commonly a concentric needle electrode is used-a hollow needle containing an insulated wire with a bevelled tip resulting in a recording area in the region of 125 9 580 lm.…”

The Relationship Between History and Physical Examination Findings and the Outcome of Electrodiagnostic Testing in Patients With Sciatica Referred to Physical Therapy

“…14,23,34 Electrodiagnostic (EDX) testing, consisting of needle electromyography (EMG) and nerve conduction studies, is used to evaluate the integrity of the neuromuscular system, including upper and lower motor neurons, the neuromuscular junction, and skeletal muscle. 11,14,22,23,31 Conducted as an extension of the clinical examination, EDX testing is the primary method used to objectively measure and document pathological changes or injury to the neuromuscular system, including proximally located spinal nerve roots. 11,14,22,23,31 Clinicians employ EDX testing to evaluate patients with sciatica, 14,23,27 with particular emphasis on the results of the needle EMG examination, which has high diagnostic specificity in these patients.…”

“…11,14,22,23,31 Conducted as an extension of the clinical examination, EDX testing is the primary method used to objectively measure and document pathological changes or injury to the neuromuscular system, including proximally located spinal nerve roots. 11,14,22,23,31 Clinicians employ EDX testing to evaluate patients with sciatica, 14,23,27 with particular emphasis on the results of the needle EMG examination, which has high diagnostic specificity in these patients. 9,14,23,31 Research has demonstrated the relationship between some patient history and physical examination findings in patients with sciatica and the presence of disc herniation or nerve root impingement on diagnostic imaging.…”

“…14,23 Monopolar needle EMG was performed on a standardized set of 6 muscles, with demonstrated reliability in patients with suspected lumbosacral radiculopathy, 8,11,13 and included the anterior tibialis, medial gastrocnemius, posterior tibialis, vastus medialis, biceps femoris short head, and the lumbar paraspinal muscles. Limb muscles were analyzed at rest and during volitional contraction.…”

“…11,13 Patients were classified as having clear, possible, or no evidence of radiculopathy. For analytic purposes, a final EDX impression was given for each patient by dichotomizing patients as having evidence or no evidence of radiculopathy based on the unmasked examiner's classification, which included consideration of the patient's medical history, physical examination, and results of the complete EDX test findings including peripheral nerve conduction testing.…”