Ependymoma of the fourth ventricle presenting with hemifacial spasm. Report of a case.

According to Gardner's hypothesis (1962) later confirmed by Jannetta (1982, 1985), hemifacial spasm can usually be related to a "vascular conflict" which takes place inside the cerebellopontine angle (CPA). Occasionally, the causative lesion can be identified as a mass encasing the facial nerve at its root exit zone (REZ) from the brain stem. The hemifacial spasm has been rarely reported in presence of a contralateral CPA mass ("false localising sign"). Hemifacial spasm in patients with masses in anatomical regions other than the CPA has to be considered exceptional. The case of an adult man harboring an ependymoma of the fourth ventricle whose only neurological sign was a left hemifacial spasm is reported. The rarity of such a condition prompted us to review the literature. Particular attention has been paid to the possible pathogenetic mechanisms and their therapeutic implications.