Brain extraction for fixed tissue banking: a technical report

Brain banking enables the study of human neural tissue and is essential for research on disease, physiology, and neuroanatomy. An essential step for whole brain studies is the extraction of the brain from the skull. Yet detailed technical descriptions of brain removal are rare, perhaps contributing to the artifactual tissue disruption sometimes observed as a result of the procedure. Here, we describe a method for whole brain extraction that could be implemented in the context of a whole-body donation, focused on the use case of fixed tissue banking. The method involves a sequential craniectomy that uses both circumferential and midline sagittal cuts, followed by a posterior approach to cutting the dura. We report the application of this protocol across n = 105 human whole-body donors. We document the time required for each procedural step and the frequency of craniectomy artifacts and skull edge artifacts at the brain surface. When the brain tissue is particularly soft, we also describe the potential use of in situ immersion fixation to increase tissue stiffness before removal, finding however that this also slows the diffusion of chemicals into the interior of the brain. Our experience suggests that the effectiveness of brain extraction can be improved via procedural optimizations. Technicians can become comfortable with the method after approximately 5-10 cases. We anticipate that improving brain extraction quality may support downstream work in the development of diagnostics and treatments for neurological and psychiatric disease.