Acoustic neuroma surgery. Translabyrinthine-transtentorial approach via the middle cranial fossa.

In our approach for acoustic tumors, the method of Morrison and King and that of Bochenek and Kukwa have been modified into one method. This modified method is basically a neuro-otological-neurosurgical team approach, extending the operative field by drilling the temporal bone and cutting the superior petrosal sinus, tentorium, and posterior fossa dura according to the size of the tumor. Therefore, for tumors slightly protruding into the posterior fossa from the prous of the internal auditory canal, only the bone adjacent to it is removed (Bochenek et al's method). For larger tumors, labyrinthectomy and mastoidectomy with the separation of the superior petrosal sinus and the tentorium and posterior fossa dura are also performed. In Morrison et al.'s method, the translabyrinthine approach is done first and the middle cranial fossa approach is performed thereafter. In contrast, in the modified method, drilling the bone from the middle cranial fossa to the tip of the mastoid--labyrinthectomy and mastoidectomy--is the first thing done after elevating the temporal lobe and revealing the middle cranial fossa, and the internal auditory canal is opened thereafter. Thirty-five cases of acoustic tumors and other cerebello-pontine angle tumors were operated on during the past 3.5 years through the middle cranial fossa. Among 30 cases of acoustic tumors, eight cases in which the tumors were confined to the internal auditory canal were operated on through the middle cranial fossa. In four cases, Bochenek et al's method was performed in which bones adjacent to the internal auditory canal and a part of the labyrinth are removed without cutting the superior petrosal sinus. In 23 cases including five cerebellopontine angle tumors, the modified translabyrinthine-transtentorial approach through the middle cranial fossa was done. This modification has the advantage that severe postoperative complications are less frequent. The surgical technique and the results are discussed.