Abstract
Determining the location of pertinent anatomic structures (ie, the internal auditory
canal [IAC]) in middle cranial fossa surgery is commonly based on indirect inferences
from bony landmarks. Several methods have been proposed for identification of the
IAC, each using bony landmarks coupled with geometric formulation. Identification
of the IAC based on bony architecture and geometry may be severely limited when a
mass lesion is present. Image-guided surgery has the advantage of rapid localization
and may be helpful in navigating a complex surgical field which has been distorted
by tumor. This study evaluates the feasibility and accuracy of the ISG viewing wand
in determining pertinent anatomic landmarks in the middle fossa of the human cadaver.
High-resolution (1 mm) computed tomography was performed on a preserved human cadaver
head in which fixed fiducial markers had been placed. Subsequently, the cadaver head
was registered in a simulated operative field, and middle fossa craniotomy was performed.
The foramen spinosum, foramen ovale, greater superficial petrosal nerve, internal
carotid artery, arcuate eminence, and IAC were identified visually, and three independent
localizations of each structure were performed with the viewing wand. Accurate localizations
were consistently performed within 1 mm for each anatomic landmark. Image-guided navigation
is both feasible and accurate in determining intraoperative landmarks in the middle
fossa. Image-guidance may enhance surgical accuracy and efficiency. Further clinical
studies evaluating image-guided techniques in the middle fossa are warranted.
