Objective: To evaluate the feasibility and accuracy of applying the commercially-available, FHC STarFix platform system for direct targeting of deep brain stimulation electrodes in a large animal model of Parkinson’s disease.

Background: Large animal models of human disease play an important role in our understanding of novel neurosurgery-based approaches for the treatment of neurological and psychiatric disease. Such work is highly dependent on precise localization of subcortical brain targets for the purpose of inserting cannulae, lesioning probes, or the placement of electrodes used for either delivering electrical stimulation or making electrophysiological recordings.  Current frame-based approaches for animal stereotaxis depend largely on indirect targeting methods that use atlas-based coordinates – often derived from a limited subject sample and inherently incapable of accounting for the substantial variation found in larger animal models. Here, we describe our adaptation of a commercially-available microtargeting platform – currently in clinical use – for implanting deep brain stimulation (DBS) leads in the non-human primate (NHP) research model.

Method: The system was evaluated through 7 lead implants across 5 NHPs, with scaled-down (2F) DBS leads implanted in either the subthalamic nucleus (STN) or the cerebellar dentate nucleus (DN). For each animal, a subject-specific, customized micro-frame was created based on preoperative MRI and stereo-CT containing skull fiducials. Leads were implanted and secured under general anesthesia through a bur hole craniotomy. Animals were allowed to recover for two or more weeks before a post-implant-CT scan was acquired.

Results: Accuracy of lead placement was determined through co-registration of a post-implant CT and pre-operative MRI, with comparisons between final localization of the lead tip relative to the planned trajectory yielding Euclidian distance ranges from 0.37 – 1.99 mm.

Conclusion: Our preliminary experience supports the potential for further development of this frameless stereotaxic system for use in large animal models, while characterizing the potential pitfalls associated with the technique. Further advancement of stereotaxic approaches in large animal models remains an important consideration, particularly in instances that involve chronic instrumentation of highly-trained animals.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/translation-of-a-subject-specific-stereotaxic-platform-to-a-large-animal-deep-brain-stimulation-research-models/