Benefits of Open Cranial Approaches for Giant Invasive Pituitary Macroadenoma

Giant invasive pituitary macroadenomas have various options for surgical resection, the most common being a transsphenoidal approach.

Up to 4% of these tumors would be considered more appropriate for an open cranial approach according to indications described in the literature. Potential tumor involvement of the intricate surrounding structures necessitates careful consideration of technique.

Open skull base techniques are useful and necessary when specific tumor characteristics and anatomy are present that limit the extent of what a transsphenoidal technique can achieve. Use of the right approach can offer adequate an surgical corridor with minimal retraction of surrounding structures. The benefits of a more complete resection should be weighed against risks of each method. Resection of macroadenomas is also associated with a risk of postoperative hemorrhage after residual tumor infarcts. Areas that cannot be accessed via transsphenoidal routes may leave tumor in areas where a hemorrhagic complication could have significant morbidity. If these areas are first approached via transcranial approach first, any residual tumor in the sella that may hemorrhage later will not carry the same morbidity. Improved visualization of skull base structures being displaced superiorly by a sellar mass is also an important advantage in avoiding damage to these critical structures.

We describe some common features of a series of pituitary macroadenomas approached with craniotomy and microneurosurgical techniques, three cases approached with cranio-orbital zygomatic and one with bicoronal craniotomy.

The C-OZ approach was used for three tumors in this series. Common features noted included a large sellar mass (>4 cm), with suprasellar extension. Parasellar invasion and major vessel encasement were seen in all. Ventricular effacement and mass effect on the temporal lobe were also seen in this series of complex tumors.

A bicoronal craniotomy was used for a large sellar mass measuring 6.7 × 7.0 × 5.8 cm. The optic nerves, optic chiasm, ICA, and ACA were all encased. There was also significant mass effect on the brainstem and extension into the bilateral middle fossae, with MCA encasement. This patient presented with rapidly progressive weakness and inability to protect the airway, but made a full neurologic recovery after rehabilitation following resection.

These cases have demonstrated that open cranial approaches for pituitary macroadenoma can be completed safely. Commonly seen features include major vessel encasement and lateral parasellar extension. In certain situations where resection via transsphenoidal approach is limited, an open cranial approach could be the only surgical option.