The efficacy of ultrasonography in the evaluation of the posterior interosseous nerve for the diagnosis of neuropathy (728.5)

Abstract

Ultrasound technology has become indispensible in the diagnosis of many neuropathies including those of the posterior interosseous nerve. Posterior interosseous nerve neuropathies have many causes notably entrapment beneath the arcade of Froshe, compression by tumors, ganglia or aberrant blood vessels. The literature regarding the anatomy of this nerve elucidates a caliber change in the long axis of the nerve as it pierces the supinator muscle. This seemingly physiological compression may be misinterpreted as entrapment. The aim of this study was therefore to evaluate the longitudinal and cross sectional anatomy of the posterior interosseous nerve at key anatomical landmarks taken from cadaveric specimens and ultrasound of normal adults. Thereby determining the reliability of ultrasound in the evaluation of compression pathologies of the posterior interosseous nerve. Longitudinal and cross sectional measurements of the radial nerve of 50 healthy adults and 30 cadaveric dissections were taken at specific intervals. Logiq E ultrasound unit with a 12Hz linear array transducer was used. Both patients and cadavers were screened for previous surgeries of the area and excluded if visible signs of intervention was present. Visualization of the cross sectional anatomy during ultrasound is challenging and measurements obtained are not directly comparable with that taken on the cadavers. However a size change was noted in the longitudinal axis but no significant difference in the cross sectional area of the nerve could be established. Ultrasonography is commonly used in diagnostics and has become an important tool in diagnosis of entrapment neuropathies among many others. Physiological compression as the nerve pierces the muscle seen on ultrasound should not be misconstrued as nerve entrapment and other modalities should be used to confirm diagnosis before surgery is performed.