In Vitro Evaluation of Posterior Fossa Stereotactic Surgery Using Frameless Custom-Built 3-Dimensional Microplatform

Our group recently completed a trial of deep brain stimulation targeting the dentate nucleus in patients with poststroke hemiparesis. Although accurate, we found significant limitations to the Leksell G frame (Elekta) for posterior fossa stereotaxis. In this study, we assess the feasibility and accuracy of a commercially available custom-built stereotactic platform for posterior fossa targeting. The smaller profile of these devices, compared with conventional stereotactic headframe make it a promising alternative when surgical access is limited.

Three anthropomorphic phantom models with posterior fossa targets marked by nylon screws were used. Each skull had a unique 4-legged microplatform designed from their fiducial location, target, and trajectory plans. We simulated posterior fossa stereotactic cannulation in the neurosurgical OR using standard equipment. Accuracy was evaluated by the deviation of the final cannula placement from the planned target and entry.

The Euclidean distance between planned target and final cannula tip position ranged between 0.4 mm (skull 3) and 1.29 mm (skull 1). The mean target deviation from plan was 0.93 mm (SD ± 0.4 mm). The mean entry deviation from plan was 0.9 mm (SD ± 0.6 mm). The mean sagittal and coronal trajectory angulation error were 0.73° (SD ± 0.4°) and 0.04° (SD ± 0.02°), respectively.

In this in vitro study, our data show that 3-dimensional printed, custom-made, single-use platforms may be feasible and accurate for posterior fossa stereotactic surgery. Further investigation with in vivo studies will be necessary to assess clinical practicality and accuracy in vivo.