Primary aberrant third nerve regeneration.

The clinical and neuroradiological features in 4 patients with the syndrome of aberrant regeneration of the third nerve are presented. In contrast to what is commonly seen, the syndrome was not preceded by third nerve palsy. A petrous apex-cavernous sinus meningioma was the underlying lesion in all 4 patients. Surgical and pathological confirmation of the diagnosis was obtained in 3. Regardless of whether the other ocular motor nerves are spared (as in our patients) or involved (as in other cases reported in the literature), primary aberrant regeneration of the oculomotor nerve appears to be characteristic of a cavernous sinus meningioma.