[Subacute proximal entrapment neuropathy of the radial nerve at the hiatus radialis].

Endogenous lesions of the radial nerve at the upper arm level and in the canalis spiralis are exceptional. Entrapment of the radial nerve in the hiatus radialis following forced arm movements, stretching, or as a consequence of pathologies of the surrounding tissue is known. We observed two patients suffering from a painful subacute middle radial nerve palsy with complete axonal degeneration caused by a lesion at the hiatus radialis, demonstrated by EMG, sonography, MRI, and surgical exploration. Successful nerve repair, in one case with a nerve graft, was performed. In both cases the most appropriate explanation was a focal neuritis with swelling of the nerve followed by strangulation at the hiatus radialis. In one case acute neuroborreliosis was the reason for the neuritis.