Endoscopic approaches to the skull base
By Edsel Kim, M.D.
Medical director, Providence Head and Neck Services
The Oregon Clinic
Obtaining access to the interface between the brain and sinuses historically has been somewhat difficult. These lesions are generally pituitary tumors, craniopharyngiomas, olfactory groove meningiomas as well as sinonasal tumors.
Traditionally, a craniofacial approach, which combines a craniotomy with an external approach of the face, was used to gain access to the floor of the anterior and middle cranial fossa of the brain. These surgeries often would be disfiguring with significant postoperative morbidity. Prolonged brain retraction and cranial neuropathies were not uncommon. Postoperative complications, while generally low, could be quite significant, including infection of the bone flaps. With certain areas of the skull base, such as the clivus and parasellar regions, gaining access via an open approach can be difficult and tedious, with significant postoperative morbidity.
Over the past 10 years, however, there has been a significant change in the management of skull base lesions. Much like the change from the open cholecystectomy to a laparoscopic cholecystectomy, skull base surgery
is now approaching the same crossroads. Instead of a large craniotomy with its associated postoperative issues, most lesions arising from the roof of the sinuses, pituitary, cavernous sinus and clivus can now be approached through a minimally invasive technique.
Fig. 1: 75-year-old female with headaches, nausea, vomiting and loss of eye movement.
Fig. 2: Two years after endoscopic approach and resection of left cavernous sinus meningioma. Complete recovery of all cranial nerves with no postoperative pain. No evidence of any recurrence.
Endoscopic skull base surgery has become a natural extension of endoscopic sinus surgery. Optics, instrumentation and intraoperative navigation have improved significantly, allowing this type of surgery to become routine instead of experimental.
Visualization with the endoscope is quite superior to the microscope. Its variety of angled lenses can be used to “look around the corner,” helping to identify and remove tumors that otherwise would have been missed.
Likewise, the benefits of having a multidisciplinary team consisting of an otolaryngologist and neurosurgeon working side by side during the entire operation bring complementary perspectives and training which cannot be achieved by a single surgeon. The primary objective with any type of surgery is complete resection of a lesion/tumor, whether through an endoscopic or an open approach. Multiple studies have shown that an endoscopic approach results in equal if not better outcomes for tumor resection.
The procedures involve little or no manipulation of the brain, and there are no cosmetic concerns because all the surgery takes place within the nose and sinuses. Recovery is less painful and takes just a few days as opposed to weeks or months. Preoperative cranial neuropathies typically begin to recover the morning after surgery, and patients are frequently discharged home within 48 hours after surgery.
The potential risks are the same as those associated with an open surgery. These include bleeding, infection and leakage of cerebrospinal fluid. However, with preoperative planning, these issues can be addressed at the time of the surgery to prevent any possible sequlae.
Skull base tumors are relatively rare conditions. However, with the advent of endoscopic skull base surgery, the approach and care for these patients has changed dramatically.