Brief retrospective of acoustic neuroma treatment
Sandifort in 1777 provided the first description of an acoustic neuroma. Sir Charles Balance was the first to remove an acoustic neuroma successfully in 1894. The classical suboccipital approach was used and this remained the standard of care until the early 1960s. There were refinements in diagnosis and treatment with major contributions from first Harvey Cushing and then Walter Dandy, but mortality and morbidity remained high. In 1960 when Dr William House first became interested in acoustic neuromas, a noted Swedish neurosurgeon Olivecrona reported a 4.5% mortality rate for small tumors and a 22.5% mortality rate for large tumors. Virtually all patients had facial paralysis and many also had ataxia. In California, the mortality rate for acoustic neuromas in 1961 was 43.5%.
At this time, rapid advances in audiology and radiology made earlier diagnosis possible. Dr William House was able to diagnose a small acoustic neuroma in a young fireman and referred him to a neurosurgeon for treatment. Faced with the possibility of mortality, the consultant recommended observation. The tumor was rapidly growing and he was operated 2 years later when it became large; he expired during the procedure. This experience prompted Dr William House to explore other management possibilities.
Operative approaches
Middle Fossa Approach
By this time, Dr House had developed the middle cranial fossa approach for decompression of the internal auditory canal for advanced otosclerosis. Although shown not to be effective for that condition, Bill recognized the possibility of approaching tumors from the middle fossa and he teamed with a Los Angeles neurosurgeon, Dr John B. Doyle, with the aim of developing a new technique for the removal of acoustic neuromas that would lower morbidity and mortality. The initial plan was to approach the tumor through the middle fossa, identify the facial nerve and trace it back to the posterior fossa, and then remove the remainder of the tumor from the suboccipital route. The first microsurgical removal of an acoustic neuroma was done on February 15, 1961, through a middle fossa craniotomy approach using the Zeiss operating microscope. A partial removal was accomplished. The patient subsequently underwent two suboccipital procedures before dying in 1967.
The initial eight cases were done using the middle cranial fossa approach, which was expanded into the cerebellopontine angle by drilling the labyrinth from above. Only partial removal could be done using this approach. It occurred to Dr House that a more direct route through the mastoid could be a better choice since he and Dr Doyle were destroying the labyrinth from above. Panse in 1904 had approached the CPA through the mastoid. His approach included a radical mastoidectomy and sacrifice of the facial nerve. Cerebrospinal fluid leaks were a major postoperative problem and this approach was greatly criticized by the neurosurgical community and never adopted.
Translabyrinthine Approach
Dr William House performed a series of cadaver dissections to work out a method to expose the CPA through the mastoid. With the aid of a surgical microscope, a dental drill, and suction irrigation, he was able to devise a method to preserve the posterior canal wall, the tympanic membrane, and the facial nerve. The translabyrinthine approach was developed.
In July, 1963, Dr William Hitselberger began to work with Dr House. They began using the translabyrinthine procedure on a routine basis for tumors of all sizes. The first series of 53 patients was published in 1964. Many of those patients underwent subtotal removal. Facial nerve preservation, however, became routine and the mortality rate was greatly reduced. As experience was gained, the percentage of subtotal removal became much less.
The neurosurgical community continued to disagree with the translabyrinthine approach, but slowly over the next several years, a few neurosurgeons became supportive. The first International Symposium on Acoustic Neuromas was organized in 1965. For 5 days leading neurosurgeons, otologists, neurologists, and audiologists attended the meeting and covered a wide range of subjects. This set the stage for early detection of acoustic neuromas and management with microsurgical techniques including the translabyrinthine approach. Over the years, it has become recognized that all three approaches (retrosigmoid, translabyrinthine, and middle fossa) are valuable. The extended middle fossa approach and the transcochlear approach were added to the surgical repertoire to allow management of most tumors in the posterior fossa. The approach is selected depending on the size and location of the tumor as well as the preoperative hearing status and the patient’s general condition.
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