Unusual functional compression of the deep branch of the radial nerve by a vascular branch (leash of Henry): ultrasonographic appearance.

PURPOSE Radial nerve compression caused by crossing branches of the recurrent radial artery - so called hypertrophic "leash(es) of Henry" (LoH) - is rare. Nevertheless it is important to diagnose the type of compression neuropathy in the forearm. MATERIALS AND METHODS We report 2 subjects with unclear neuropathy of the deep branch of the radial nerve (DBRN) who showed compression by an LoH on high resolution ultrasound (HRUS) assessment. The shape and echotexture of the radial nerve were assessed with respect to the typical outer and inner texture of peripheral nerves in HRUS. Using color and/or power Doppler, an exact analysis of the surrounding soft tissues follows to search for possible atypical vessels compressing the nerve. RESULTS In both patients a hypertrophic leash of Henry was identified with color/power Doppler ultrasound and the direct vascular compression of the DBRN was readily demonstrated. The involved nerve segment was enlarged with a mean transverse diameter of 2.7 mm and 1.9 mm, with a hypoechoic change and partial masking of the inner fascicular texture of the nerve at the level of the LoH. CONCLUSION In summary, both presented patients showed a unique topographic concordance of a textural change of the deep radial nerve (i. e., swelling and inner hypoechoic fascicular change) and the causative hypertrophic crossing artery. The use of power Doppler ultrasound in addition to caliber and texture changes shown on grayscale ultrasound and the functional visualization of pulsating vessels should be included in every sonographic examination of patients with chronic forearm pain symptoms.