Pre- and Intraoperative Management of Brainstem Lesions

Brainstem cavernous malformation (BSCM) is a typical brainstem pathology that can lead to significant neurological morbidity. Before making a surgical decision for a patient with BSCM, it is essential to balance the surgery against the natural history of BSCM since individualized risk assessment is crucial for a comprehensive understanding of the natural course of conservatively treated BSCMs (Chapter 2). In patients with symptomatic and accessible BSCMs, surgery is recommended, however, in some deep-seated locations, surgery is more controversial because of the relatively high morbidity and mortality rates. Therefore, the timing of the surgical option still needs further investigation (Chapter 3). For the surgical treatment in patients with BSCMs, although many safe entry zones (SEZs) into the brainstem have been proposed, it is still debatable on some of them (Chapter 4). Intraoperative direct stimulation is a promising technique in brain surgeries involving eloquent areas. It has been reported to assist in preserving the motor tracts during the resection of (sub)cortical lesions. However, it is sparsely explored for mapping and monitoring the corticospinal tract in brainstem surgery (Chapter 5). In this thesis, we have investigated safe brainstem surgery from two aspects - preoperative evaluation and intraoperative direct stimulation. The results promote a better understanding of the hemorrhage rate in untreated BSCM before surgical recommendation and help on the timing of surgical decision-making. In addition, this thesis sheds light on the limitation of SEZs in surgical planning for patients with BSCM and the clinical value of direct stimulation for monitoring and mapping of the corticospinal tract during brainstem surgery. These findings contribute to safe surgical planning and lesion resection for brainstem pathologies, especially for the BSCMs

A multimodal computational pipeline for 3D histology of the human brain

ABSTRACT: Ex vivo imaging enables analysis of the human brain at a level of detail that is not possible in vivo with MRI. In particular, histology can be used to study brain tissue at the microscopic level, using a wide array of different stains that highlight different microanatomical features. Complementing MRI with histology has important applications in ex vivo atlas building and in modeling the link between microstructure and macroscopic MR signal. However, histology requires sectioning tissue, hence distorting its 3D structure, particularly in larger human samples. Here, we present an open-source computational pipeline to produce 3D consistent histology reconstructions of the human brain. The pipeline relies on a volumetric MRI scan that serves as undistorted reference, and on an intermediate imaging modality (blockface photography) that bridges the gap between MRI and histology. We present results on 3D histology reconstruction of whole human hemispheres from two donors