Trigeminal schwannoma as a cause of chronic, isolated sixth nerve palsy

We treated two patients with trigeminal schwannomas, each of whom had an isolated, ipsilateral, abducens nerve palsy. Both patients initially had normal computed tomographic scan results and no neurologic signs of trigeminal nerve dysfunction. Trigeminal dysfunction did not develop until several years after the initial sixth nerve palsy, at which time a repeat examination disclosed the schwannoma. Accurate detection of a trigeminal schwannoma requires a careful clinical examination and appropriate neuroimaging studies. When such studies give normal results, they should be repeated if symptoms worsen or if new symptoms develop.