Schwannoma of the median nerve (even outside the wrist) may mimic carpal tunnel syndrome.

Over the last 3 years we have observed 5 cases of median nerve schwannoma that clinically simulated carpal tunnel syndrome (CTS). We describe the atypical clinical-neurophysiological picture indicating to perform ultrasonography (US). We retrospectively re-evaluated 5 cases of schwannoma that clinically simulated CTS. Five consecutive patients were referred to the neurophysiopathology laboratory. All patients complained of symptoms and had a neurophysiological examination that might have indicated CTS. Nevertheless we performed US because of some incongruous aspects. In cases of atypical abnormalities at neurophysiological and clinical examination, or dissociation between neurophysiological and clinical findings, physicians should consider the presence of a median nerve tumour. Here, US evaluation is very useful as supporting diagnostic methodology to assess the anatomopathological condition of the nerve lesion and must not be limited to the wrist.