Is the chiasm-pituitary corridor size important for achieving gross-total resection during endonasal endoscopic resection of craniopharyngiomas?

Abstract

OBJECTIVE Craniopharyngiomas arise from the pituitary stalk, and in adults they are generally located posterior to the chiasm extending up into the third ventricle. The extended endonasal approach (EEA) can provide an ideal corridor between the bottom of the optic chiasm and the top of the pituitary gland (chiasm-pituitary corridor [CPC]) for their removal. A narrow CPC in patients with a prefixed chiasm and a large tumor extending up and behind the chiasm has been considered a contraindication to EEA, with a high risk of visual deterioration and subtotal resection. METHODS A database of all patients treated in the authors' center (Weill Cornell Medical College, NewYork-Presbyterian Hospital) between July 2004 and August 2016 was reviewed. Patients with craniopharyngiomas who underwent EEA with the goal of gross-total resection (GTR) were included in the study. Patients with postfixed chiasm or limited available preoperative imaging were excluded. Using preoperative contrast-enhanced T1-weighted sagittal midline MR images, the authors calculated the CPC as well as the distance from the chiasm to the top of the tumor (CTOT). From these numbers, they calculated a ratio of the CPC to the CTOT as a measure of difficulty in removing the tumors through the EEA and called this ratio the corridor index (CI). The relationship between the CI and the ability to achieve GTR and visual outcome were measured. RESULTS Thirty-four patients were included in the study. The mean CPC was 10.1 mm (range 5.2-19.1 mm). The mean CTOT was 12.8 mm (range 0-28.3 mm). The median CI was 0.8; the CI ranged from 0.4 to infinity (for tumors with a CTOT of 0). Thirty-two patients had GTR (94.1%) and 2 had subtotal resection. The CPC value had no relationship with our ability to achieve GTR and no effect on visual or endocrine outcome. CONCLUSIONS EEA for craniopharyngioma is generally considered the first-line surgical approach. Although a narrow corridor between the top of the pituitary gland and the bottom of the chiasm may seem to be a relative contraindication to surgery for larger tumors, the authors' data do not bear this out. EEA appears to be a successful technique for the majority of midline craniopharyngiomas.

Lessons learned in the evolution of endoscopic skull base surgery

“…7,12,16,21,40 Furthermore, it has been shown that a narrow surgical window between the pituitary gland and optic chiasm does not preclude a ventral approach. 64 Recurrent tumors present significant challenges when treated via either approach, but with ESBS it appears that the extent of resection (87.0%) and visual outcomes (76.5% improvement) remain similar, and major complication rates are comparable to first-time rates (3.6% first time vs 0.0% recurrent), but with a higher rate of new postoperative diabetes insipidus for reoperations (47.0% first time vs 80.0% recurrent). 21 Prior radiation, however, continues to make further surgery more complicated, regardless of the approach.…”

Surgical management of craniopharyngiomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section

“…They may present as entirely solid or with an associated cystic component and may frequently engulf neurovascular structures in the interpeduncular and suprasellar cisterns. In adults, they arise most commonly posterior to the chiasm and extend posteriorly into the third ventricle [138]. The papillary histopathological type account for at least one-quarter of cases in the adult age group and this finding translates into more solid lesions with fewer calcifications [4,198], a homogeneous contrast enhancement and a thickened pituitary stalk [193].…”

Endonasal endoscopic transsphenoidal resection of intrinsic third ventricular craniopharyngioma: surgical results

“…16 On occasion, sacrifice of a descending branch of the superior hypophyseal artery is necessary to gain appropriate surgical access to the interval between chiasm and pituitary gland, also known as the chiasm-pituitary corridor. 24 Great care is taken to preserve branches of the superior hypophyseal artery to the chiasm, which can be swept north following transection of the descending branch.…”

“…Tumor-related expansion frequently enlarges the interval between the chiasm, which is often displaced anteriorly, and the infundibular recess. 23,24 In larger tumors, the inferior margin of the third ventricle is commonly displaced inferiorly, where it can be stretched to a thin translucent membrane. Access to the tumor capsule can be obtained via an incision in the thin membrane occupying the region between anteriorly displaced chiasm and stalk.…”