Sub-Temporal Approach to Suprasellar Retrochiasmatic Tumors: Case Series and Anatomic Cadaveric Correlation
Objectives: Contemporary approaches to the sella and supra-sellar spaces include fronto-temporal craniotomy, its variants and the endoscopic endonasal transsellar approach. Suprasellar retrochiasmatic lesions with posterior extension however are very difficult to access and remove due to close proximity to important neurovascular structures. Aggressive resection can cause significant morbidity including hypothalamic obesity, pituitary dysfunction and visual defects. While the subtemporal approach to supra sellar retrochiasmatic tumors has been described in the literature, the evidence is scarce. We describe our experience with the subtemporal approach to such tumors as a safe and simple operation with the goal of maximal safe resection.
Methods: A retrospective analysis was performed on 5 consecutive patients who underwent subtemporal approach for a suprasellar retrochiasmatic tumor. All demographic, clinical and radiographic data were recorded and analyzed. Additionally, cadaveric dissection was performed in 2 specimens to illustrate the relevant anatomy, surgical view and working angles of the surasellar retrochiasmatic space using the subtemporal approach.
Results: 5 patients were operated on from November 2011 to July 2013. All patients were female with mean age of 51.8 (25–77). 3 patients had craniopharyngiomas and 2 had pituitary adenomas. Two patients presented with vision loss, 1 with diplopia and 2 with hypopituitarism. All tumors were imaged with MRI and located in the suprasellar and retrochiasmatic space; 2 invaded the cavernous sinus, 3 extended into the retrosellar space, and 1 extended into the retroclival space. The mean maximum diameter of the tumors was 2.98 cm (1.7–3.4). All tumors were operated on with a subtemporal approach with the goal of surgery being optic apparatus decompression and preservation of the pituitary-hypothalamic axis. Subtotal resections (<95% tumor removed) was achieved in 3 patients while near total resections (95–99%) was achieved in 2 patients. Residual tumor was accepted if it was particularly adherent to the optic apparatus, pituitary-hypothalamic axis or brainstem perforators. Four patients returned home after surgery. one patient (a 77 year old woman with gait instability due to significant temporal lobe and brainstem compression prior to surgery) required acute rehabilitation.
Two patients underwent standard fractionated radiotherapy (IMRT) for their residual tumor. There was 1 complication: an epidural hematoma was evacuated post-operative day 4. Mean follow-up was 7.2 months (1.5–18 months). 2 patients developed new post-operative adrenal insufficiency requiring steroid replacement. None of the patients developed any permanent neurologic deficit; 3 patients' vision stabilized and 2 others improved. 1 patient's preoperative diplopia dramatically improved. There were no hypothalamic insults clinically or radiographically.
The subtemporal approach was performed in 2 cadaveric heads. Direct visualization of the optic chiasm, oculomotor and trochlear nerves in addition to perforators to the brainstem is well achieved. The pituitary stalk is visible extending superior-posteriorly. The suprasellar, retrosellar and retroclival spaces are all easily approachable.
Conclusion: The subtemporal approach allows for direct visualization of the retrochiasmatic space as well as extension in the retro-sellar and posterior fossa compartments. Preservation and control of the perforators to the hypothalamus, pituitary stalk and optic chiasm can be achieved safely and efficiently with this approach.