Management of colloid cyst of third ventricle.

Colloid cysts are usually located in third ventricle and are believed to be derived from either primitive neuroepithelium or endoderm. Patients may remain asymptomatic for long time while some can present with paroxysmal headache, gait disturbance, nausea, vomiting, behavioral changes, weaknesses of lower limbs, impaired memory, new learning disability and sudden death. Computed tomography usually reveals a well-defined round or oval nonenhancing lesion. Although magnetic resonance imaging (MRI) signal intensity of colloid cysts is variable, the most common appearance is hyperintensity in T1-weighted sequences and iso to hypointensity in T2-weighted sequences. Observation, stereotactic aspiration, microscopic or endoscopic approaches and shunt surgery are various management options. Transcallosal and transcortical microscopic (with or without tubular retractor) approaches are mainly useful in normal-sized and dilated ventricles respectively. Endoscopic technique is an effective alternative to microsurgical technique but total resection and long-term recurrence remains a concern. Utilization of two instruments, the bi port technique and tubular retractor can be helpful in selected patients to overcome limitations. Although total excision should be aimed, subtotal excision and coagulation of residual cyst wall usually results in good long-term results without any growth of remnant wall. Conversion to an open procedure may be required in some patients.