Transient oculomotor nerve palsy in colloid cyst: An unexpected neurological link

Colloid cysts are benign, slow-growing tumors of the third ventricle, usually presenting in adults. Pediatric cases are uncommon and may exhibit atypical symptoms. We report a 15-year-old female who presented with an acute onset of complete ptosis and diplopia consistent with pupil-involving third nerve palsy, preceded by severe headache and vomiting. Fundus examination showed bilateral grade 3 papilledema. Magnetic resonance imaging (MRI) revealed a 1.5 × 1.3 cm cyst in the anterior third ventricle, causing obstructive hydrocephalus. The patient underwent emergency endoscopic excision of the cyst followed by a ventriculoperitoneal shunt for persistent headache. Postoperatively, she had complete recovery of ocular motility, ptosis, and papilledema. This case highlights a rare presentation of third nerve palsy as the initial sign of a colloid cyst, likely secondary to raised intracranial pressure rather than direct compression. Early recognition and timely surgical intervention are crucial for favorable neurological and visual outcomes in such cases.