The origin of neurosurgery as a modern and separate branch of surgery dates back to the end of the 19th century. Skull base neurosurgery has always been a challenge to neurosurgeons due to the depth of the location and the complex but important anatomical relationships in this area. Many prominent and pioneering neurosurgeons contributed substantially to the development of skull base neurosurgery. The discovery of anesthesia, antiseptic techniques, and cerebral anatomy established a foundation from which brain surgery could evolve. The earliest approaches took place at the base of the skull. In 1879, William MacEwen was the first to successfully remove a brain tumor from over the right eye in a 14 year old patient. However, the exact pathology of the tumor is unclear. In 1884, Francesco Durante removed an olfactory groove meningioma from the base of the skull in a 35-year-old woman^[1].

Lateral skull base tumors

The history of lateral skull base tumor management is best understood by means of the history of acoustic neuroma (AN) surgery^[2]. In 1891, Charles McBurney was the first to attempt a resection of an AN, but failed. Soon after, in 1894, Charles Balance was the first to report successful complete removal of an AN^[3]. During the earliest era of AN surgery, surgical mor-tality could be as high as 80%. More modern surgical techniques appeared during the Harvey Cushing era (early 1900s). By promoting delicate and meticulous surgical technique, decreasing cerebellar retraction and relieving cerebrospinal fluid pressure to improve the operative space, Cushing reduced the surgical mortality to 20% in his naked eye era^[4]. By building on the developments made by Cushing, Walter Dandy was able to advance the modern surgical era. In 1918 and 1919, Dandy invented ventriculography and pneumoencephalography, allowing neurosurgeons to identify the approximate location and size of brain tumors for the first time. In 1961, William House introduced the operative microscope and changed neurosurgery forever^[5]. This microscope improved observation of the cranial nerves and blood vessels and permitted more complete tumor resection, with decreased morbidity. Neurosurgeons represented by Yasargil took full advantage of this technology and pushed skull base neurosurgery into a new era.

Transnasal surgery

In 1907, Schloffer was the first to remove a pituitary tumor using a transnasal, transsphenoidal approach. However, for this approach a flap needed to be created in the nose on one side, which caused significant facial scarring. The endonasal, transseptal, transsphenoidal approach was first described by Oskar Hirsch in 1910. Between 1910 and 1925, Harvey Cushing used Hirsch’s approach to perform operations in 231 patients with pituitary tumors, with a mortality rate of only 5.6%. Subsequently, Cushing almost completely abandoned the transnasal approach and reverted to using the transcranial method. Cushing did not specify a reason for doing this. Historians speculate that without advanced imaging technology and clear preoperative diagnosis, unexpected lesions such as meningiomas, chordomas and craniopharyngiomas could be better managed with using the above. Owing to Cushing’s prominent influence in the neurosurgical community, the transsphenoidal approach was almost completely abandoned in the United States. At that time, only a few neurosurgeons, including Hirsch, Hamlin, Norman Dott and Gerard Guiot, attempted to utilize the virtues of the transsphenoidal approach and reported excell¬ent long-term results. By introducing the operating microscope and specialized instruments in the 1960s, Jules Hardy reintroduced the transsphenoidal approach in North America. The transsphenoidal approach used by most neurosurgeons today is a modification of that refined by Hardy. This approach provides access to almost all areas of the anterior base of the skull.

Endoscopy

The development of endoscopy can be traced back to the early 1800s. In the 1950s and 1960s, Harold H. Hopkins and Karl Storz developed the cylindrical lenses that are used in the endoscope today. In 1910, Victor Darwin Lespinasse first performed ventricular endoscopy and coagulation of the choroid plexus for the treatment of hydrocephalus. Walter Dandy also planned to use the endoscope to treat communicating hydrocephalus, but his operation was unsuccessful. It was not until the 1970s that the use of endoscopy returned to neurosurgery. Technical advances brought about major progress in the development of endoscopy and related instrumentation, especially high quality of visualization. In 1978, Bushe and Halves used the endoscope to perform pituitary surgery^[6]. One of the main advantages of the endoscope is in the provision of a panoramic view of the operating field. Jho and Carrau were among the first to describe a series of patients where the endoscope was used exclusively to resect pituitary adenomas^[7]. Concurrent with Jho and Carrau’s work on the endoscopic approach, Kassam and Snyderman, expanded on the previous unilateral endoscopic approach and developed a bilateral endo¬nasal team approach allowing exposure of tumors from the crista galli to C-2^[8]. Joseph suggests that the endoscopic approach might represent a paradigm shift, perhaps equivalent to the introduction of the microscope, in approaching various skull base lesions^[8].