Advanced surgical approach for selective amygdalohippocampectomy through neuronavigation

OBJECTIVE: Selective removal of the mesiobasal temporal structures through the transsylvian approach was introduced by Yasargil and Wieser in 1982. Th is alternative to standard temporal lobectomy provides excellent outcomes f or seizure control. Basic actions in the transsylvian fissure exposure main ly serve to orient the surgeon, and they carry the risk of vasospasm and ve ssel damage. The aim of our study was to reduce landmark-guided surgery ste ps through neuronavigation. METHODS: During a 14-month period, 16 selective amygdalohippocampectomies w ere performed with the aid of the SMN (Carl Zeiss, Inc., Thornwood, NY) or StealthStation (Sofamor Danek, Memphis, TN) optically guided systems. We ad ded safety procedures to the operation (including intraoperative rereferenc ing, obtaining additional bony reference points before craniotomy, performi ng a small craniotomy and making an accurate dural incision, and using cont rast medium for vessel visualization) to develop a method that relies on na vigational systems without further orientation by anatomic landmarks. RESULTS: Originally, performing an amygdalohippocampectomy required exposin g the sylvian fissure from the carotid bifurcation to 2 cm beyond the middl e cerebral artery bifurcation, which exposed one-third of the insula. By de termining the entry point at the limen insulae and the target at the tip of the temporal horn, the mandatory extent of the opening to the sylvian fiss ure can be projected. Therefore, the exposure of the fissure can be limited to exactly the extent required for the transventricular approach through t he uncinate fasciculus. CONCLUSION: Computer-assisted surgery is an effective tool in eliminating t he exposure of anatomic landmarks in selective amygdalohippocampectomy. Thi s modification combines the precision of targeting with minimal cortical an d vessel traumatization.