WS7.10. Neuromuscular ultrasound in focal neuropathies

Neuromuscular ultrasound is rapidly evolving as an excellent diagnostic tool in the evaluation of focal neuropathies. It can also be of use in understanding the underlying pathological mechanism of focal neuropathies. Unlike length-dependent polyneuropathies, focal neuropathies are more likely to be associated with structural abnormalities that can be easily recognized by imaging modalities. Point of care ultrasound helps with rapid examination of long segments of multiple nerves in the out-patient setting. This can result in early triaging of patients and rapid management decisions. Other advantages include easy patient tolerability when compared to nerve conduction studies and lower cost. The sonographic abnormalities that are commonly associated with focal neuropathies include focal enlargement, hour-glass constriction, change in neural architecture, decreased mobility of the nerve or increased vascularity. Neuromuscular ultrasound is particularly helpful with the correct localization of focal entrapment neuropathies. It can help also in the detection of dynamic compression. Its role as a diagnostic tool has extended beyond entrapment neuropathies to include traumatic neuropathies, infective and non-infective inflammatory neuropathies and peripheral nerve sheath tumors. It can also be of use in detecting extra-neural abnormalities like tenosynovitis, soft tissue tumors, entrapment or compression from metallic implants. Other lesser recognized uses include the detection of anatomical variants like bifid median nerves, persistent median artery, anomalous muscles and ulnar nerve subluxation at the elbow. Pathologies of the brachial plexus like inflammatory plexitis and thoracic outlet syndrome can also be detected by sonographic studies. The use of neuromuscular ultrasound can be complemented when used in conjunction with nerve conduction studies. Neural changes can be detected by sonographic studies very early into the disease at sites of focal pathologies like conduction block or temporal dispersion. Recent uses of ultrasound include its role as a tool in guiding with the therapeutic interventions for focal focal neuropathies. These include administration of steroids or local anesthetics in entrapment neuropathies or in those patients with neuralgic pain. The latter include carpal tunnel syndrome, meralgia paresthetica or other lesser known painful neuralgic disorders.