Background: Endoscopic resection is becoming a well-established treatment option for patients with colloid cysts of the third ventricle. A disadvantage of this approach is the decreased ability to resect cysts in their entirety. Correlations between magnetic resonance imaging (MRI) features and cyst content could potentially help surgeons decide on the extent of resection and approach. We attempted to identify a correlation between patients' MRI imaging patterns and difficult cyst removal, post-operative adverse outcomes and the need for cerebrospinal fluid (CSF) diversion, in order to detect markers that may affect pre-surgical planning.
Method: A retrospective examination of all patients' records that underwent a colloid cyst excision attempt at our institution between 2001 and 2014, and which had a minimum 1-year follow-up was compiled.
Results: Of the 25 patients fulfilling the criteria, we found cysts with a low T2 signal, specifically when combined with high T1 signal, to be significantly correlated with piecemeal, difficult removals. Correlation was also found between high T2 signal cysts and pre-operative hydrocephalus. Among patients that had pre-existing hydrocephalus, those that required a piecemeal removal possessed a strong trend towards a need for subsequent shunting.
Conclusions: We found specific MRI features suggestive of difficult cyst excision. In a subgroup of patients with pre-operative hydrocephalus and imaging features suggestive of difficult removal, significantly higher rates of shunting were observed. We therefore recommend an open approach in cases of low T2, high T1 signal cysts with a diameter of over 15 mm, or CSF shunting in poor surgical candidates. Smaller cysts, with a low T1 signal, a high T2 signal and pre-operative hydrocephalus, constitute a subgroup in which we recommend endoscopic intervention as the procedure of choice.
Keywords: Colloid cyst; Difficult excision; Hydrocephalus; MRI features; Neuroendoscopy.