Fourth Ventricle Epidermoid Cyst: Case Report of Precision Telovelar Microsurgery, Functional Preservation, and Lifelong Surveillance

<b>Background and Clinical Significance</b>: Fourth ventricular epidermoid cysts are among the least frequently encountered intracranial tumors (less than 1%). Their slow growth pattern along cisternal and subarachnoid spaces, and their close proximity to neurovascular structures (brainstem-cerebellar), create difficulty for surgical treatment. Total removal is often complicated by the capsule's adherence to eloquent structures and requires a thoughtful surgical approach of weighing radical resection versus neurologic/function preservation. This case description provides an example of using careful clinical-radiological correlation and anatomy-dissecting microsurgery as a method of permanent decompression and neurologic recovery with low operative risk. <b>Case Presentation</b>: A 57-year-old female presented with impaired stability of gait, gaze-evoked nystagmus, appendicular ataxia, minimal ipsilateral hypotonia, and mild bulbar dyscoordination. Imaging (MRI, MRA) revealed a large, lobulated mass that was lobulated and avascular centered in the left cerebellar hemisphere, with an extension into the vermis and cisterna magna, and partial filling of the fourth ventricle with classic epidermoid imaging. Resection was performed via a midline suboccipital telovelar approach with microsurgery, relying on native arachnoid planes and quadrant opportunities of decompression, while preserving critical neurovascular structures. A thin rim of capsule intimately adherent to the floor of the ventricle was intentionally left to minimize irreversible cranial nerve injury. Histology showed keratinizing stratified squamous epithelium with laminated keratin and cholesterol clefts. Following resection, truncal stability, limb coordination, and ocular pursuit improved without additional deficits. Initial and 3-month postoperative MRI showed total decompression, re-established CSF pathways, and no recurrence. <b>Conclusions</b>: This case demonstrates that maximal safe resection (with function preservation) through natural anatomy corridors can achieve excellent neurologic results in fourth ventricular epidermoids. Lifelong MRI surveillance will be needed due to the srisk of delayed recurrence even after near-total resection.