Nerve Conduction Studies: Normal Adult Values Upper Extremity Studies Motor Studies Nerve Record Amplitude (mV) Conduction Velocity (m/s) Distal Latency (ms) Distal Distance (cm) Median Abductor pollicis brevis (APB) ≥4.0 ≥49 ≤4.4 7 Ulnar Abductor digiti minimi (ADM) ≥6.0 ≥49…
Electrodiagnostic (EDX) studies are generally well tolerated and rarely associated with any significant side effects. Most nerve conduction studies (NCSs) use surface stimulating and recording electrodes, which are not invasive. However, electrical current is applied to the patient when stimulating…
In the office, hospital, and home, we are surrounded by equipment, appliances, and many other devices powered by electricity. Although knowledge of electricity and electronics is not needed to watch television, talk on the telephone, or use a toaster, these…
In conjunction with the clinical examination, electrodiagnostic (EDX) studies frequently play a key role in the evaluation of neuromuscular disorders in infants and children. Indeed, there are a large number of neuromuscular disorders that present in the pediatric age group.…
The majority of electrodiagnostic (EDX) studies are performed on outpatients, even in those electromyography (EMG) laboratories that are physically located within a hospital. However, an increasing number of EDX studies are done on patients in the intensive care unit (ICU).…
The myotonic muscle disorders compose a group of disorders characterized by muscle stiffness, pain, and sometimes weakness, which may be intermittent or constant. The primary periodic paralyses are rare inherited disorders associated with attacks of muscle paralysis. Depending on the…
In the evaluation of patients with suspected myopathy, molecular genetics has supplanted the need for electrodiagnostic (EDX) studies or muscle biopsy in many patients with inherited conditions. Moreover, in patients with suspected myopathy and no evidence of an inherited condition,…
Disorders affecting the neuromuscular junction (NMJ) are among the most interesting and rewarding seen in the electromyography (EMG) laboratory. These disorders are generally pure motor syndromes that usually preferentially affect proximal, bulbar, or extraocular muscles. They are confused occasionally with…
Sciatic neuropathies are uncommon in the electromyography (EMG) laboratory. When they occur, patients often present in a manner similar to that of peroneal neuropathy. Indeed, a foot drop from an early sciatic neuropathy may be difficult or impossible to distinguish…
The anterior rami of the L1–S3 roots come together to form the lumbosacral plexus, from which all major lower extremity nerves are derived. Disorders of the lumbosacral plexus are distinctly uncommon, but when they occur, they typically present with a…