電気生理学的検査　Update

抄録

In this manuscript, I will mention two topics as the update of electrodiagnostic examinations. One is the clinical and electrophysiological diagnosis of amyotrophic lateral sclerosis (ALS), and the other is electrodiagnosis of plexopathies including true neurogenic thoracic outlet syndrome (TN–TOS).

Revised El–Escorial criteria (R–EEC), the most famous diagnostic criteria for ALS, was criticized by its low sensitivity and its disrespect for the fasciculation potentials. Awaji criteria have been proposed, which reappraised the fasciculation potentials and introduced the interoperability between clinical and electrical findings. However, some studies including ours documented lower sensitivity of Awaji criteria than R–EEC, which was due to the fact that two regions with upper motor neuron (UMN) signs were required in the Awaji criteria to become study eligible. Modified or updated Awaji criteria have been proposed, which achieved the highest sensitivity. However, patients lacking UMN signs cannot be diagnosed using any of the existing criteria. As the more sensitive and specific signs, we investigated the fasciculation potentials themselves, spontaneous activities in the trapezius muscle, and the decremental response in repetitive nerve stimulation test in the trapezius muscle.

For the electrodiagnosis of brachial plexopathies, combination of sensory conduction studies is promising. Among brachial plexopathies, the concept of thoracic outlet syndrome (TOS) has been the topic of debate. Professor Wilbourn in Cleveland clinic argued that the true neurogenic TOS (TN–TOS) is the only established disorder among neurogenic TOS, and criticized the concept of classical TOS that has been frequently treated surgically, naming it as the disputed neurogenic TOS. TN–TOS is a motor–dominant disorder presenting with thenar atrophy and impaired skilled movement of digits. Sensory symptoms are usually minimal. Nerve conduction studies clearly document the lower trunk lesion dominant in the T1 component.