Título

PERMANENT VISUAL LOSS AS A COMPLICATION OF DECOMPRESSIVE SURGERY FOR THE TREATMENT OF POSTERIOR FOSSA TUMOR

Objetivo

Permanent and profound visual loss is not expected after successful posterior fossa tumor removal.
Here, we describe a patient that developed severe and permanent visual loss after posterior fossa tumor removal. We also discuss mechanism and procedures to minimize the risk of such complications.

Relato do Caso

A 13-year-old girl presented to the emergency room with acute onset of severe headache, vomits and episode of visual blurring. Fundoscopy showed papilledema. Computer tomography of the brain revealed a posterior fossa tumor with enlarged ventricules (Fig1A). Prompt ventriculoperitoneal (VP) shunt was performed to control intracranial pressure (ICP). After shunt placement, magnetic resonance imaging (MRI) showed persistence, although reduced, hydrocephalus. An uncomplicated suboccipital craniotomy was performed for complete tumor removal. Pathology demonstrated a grade I juvenile pilocytic astrocytoma.
Postoperatively, the patient woke up mute, oscillating periods of irritation and inattention and could not make eye contact. An MRI revealed reduction in the ventricular system, with no new nor residual lesion (Fig1B).
Five months later, she was referred to our clinic. Despite fluent speech and normal behavior, she claimed that since surgery she noticed visual loss in both eyes with only slight improvement over the following months. Her visual acuity was finger counting at 2 meters in both eyes with pupils reacting briskly to light. Fundoscopy revealed bilateral optic disc pallor (Fig2A). Optical coherence tomography showed significant bilateral retinal nerve fiber layer and ganglion cell layer loss (Fig2B).

Conclusão

Permanent visual loss after posterior fossa tumor removal is an uncommon but devastating complication that may occur in patients with pre-operative papilledema. Sudden drop of ICP and vasoregulatory mechanism probably play a role In its genesis.
Surgeons must be aware of such complication and whenever possible pursue slow reduction of ICP and papilledema before surgery to minimize the risks of such complications.