Viability of Miniframe-Guided Infusion Cannula Placement in the Posterior Fossa in Cadaveric Specimens

BACKGROUND AND OBJECTIVES: The dentate nucleus represents a promising target for gene therapy delivery in the treatment of cerebellar diseases such as Friedreich's ataxia; however, existing MRI-compatible miniframe systems have not been investigated for feasibility of infusion cannula placement targeting the posterior fossa structures. This study evaluates the ability to access the dentate nuclei in cadaveric specimens using a commercially available MRI-guided mounting system. METHODS: MRI-compatible miniframes were secured to the suboccipital region of cadaveric heads using commercially available bone anchor screws and/or longer, investigational screws. Tissue thickness was measured post hoc, and trajectory errors were recorded to estimate the viability of vector delivery. Statistical comparisons were made using paired, two-tailed Student's t -tests. RESULTS: Six cadaveric heads were tested with body mass index (BMI) ranging from 16.64 to 43.74 kg/m 2 . Stable percutaneous base fixation was achieved in specimens with lower BMI and skin thickness. Otherwise, longer investigational screws or skin dissection were required. Inferior positions for potential screw placement demonstrated significantly thicker soft tissue (14.14 mm [95% CI: 3.83-24.45]; P = .019) and thinner bone (−4.62 mm [95% CI: −6.61 to −2.63]; P = .003) compared with superior positions. Median pre- and post-drill targeting errors were 0.70 mm and 0.90 mm, respectively, with submillimetric accuracy in most cases. Higher BMI trended toward increased soft tissue thickness and greater post-drill error, but these findings did not reach statistical significance. CONCLUSION: The use of MRI-guided navigation to target the posterior fossa structures such as the dentate nucleus is feasible but requires preoperative consideration of scalp thickness. Mounting of the base is possible; however, longer skull fixation and offset screws are needed to achieve proper fixation.