Recurrent Bilateral Trochlear Nerve Palsy Revealing Bilateral Trochlear Nerve Schwannomas: A Case Report

Background Schwannomas are benign tumors originating from Schwann cells and account for approximately 8% of all intracranial neoplasms [ 1 ], [ 2 ]. They typically arise from sensory cranial nerves, making their origin from the purely motor trochlear (IV ) nerve a rare event [ 1 ]. While unilateral cases are uncommon, the presentation of bilateral trochlear schwannomas is exceptionally rare, with to our knowledge only one other case of isolated bilateral schwannomas having been previously reported in the literature [ 3 ]. The presence of multiple schwannomas raises suspicion for a genetic predisposition syndrome. The main differential diagnoses include Neurofibromatosis type 2 (NF2) and schwannomatosis [ 3 ]. While NF2 is defined by bilateral vestibular schwannomas, schwannomatosis is characterized by multiple non-vestibular schwannomas and is associated with different gene mutations. An isolated presentation affecting only the trochlear nerves, as in our patient, represents a highly atypical phenotype. We report a case of recurrent bilateral trochlear palsy revealing this rare entity, highlighting the significant diagnostic pitfalls and the modern, evidence-based management pathway. Publication History Received: 02 November 2025 Accepted: 02 December 2025 Article published online: 04 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 14, 70469 Stuttgart, Germany