Tactics: an open-source platform for planning, simulating and validating stereotactic surgery.

Frame-based stereotaxy is widely used for planning and implanting deep-brain electrodes. In 2013, as part of a clinical study on deep-brain stimulation for treatment-resistant depression, our group identified a need for software to simulate and plan stereotactic procedures. Shortcomings in extant commercial systems encouraged us to develop Tactics. Tactics is purpose-designed for frame-based stereotactic placement of electrodes. The workflow is far simpler than commercial systems. By simulating specific electrode placement, immediate in-context view of each electrode contact, and the cortical entry site are available within seconds. Post implantation, electrode placement is verified by linearly registering post-operative images. Tactics has been particularly helpful for invasive electroencephalography electrodes where as many as 20 electrodes are planned and placed within minutes. Currently, no commercial system has a workflow supporting the efficient placement of this many electrodes. Tactics includes a novel implementation of automated frame localization and a user-extensible mechanism for importing electrode specifications for visualization of individual electrode contacts. The system was systematically validated, through comparison against gold-standard techniques and quantitative analysis of targeting accuracy using a purpose-built imaging phantom mountable by a stereotactic frame. Internal to our research group, Tactics has been used to plan over 300 depth-electrode targets and trajectories in over 50 surgical cases, and to plan dozens of stereotactic biopsies. Source code and pre-built binaries for Tactics are public and open-source, enabling use and contribution by the extended community.

Synchronous glioblastoma multiforme and chondrosarcoma: A case report and review of the literature.

This case report describes the rare occurrence of two individually uncommon tumours found in synchronous manner in an otherwise healthy patient with no history of malignancy. We believe this to be the first reported case of synchronous glioblastoma and chondrosarcoma. While primary rib lesions metastasising to brain are rarely reported and primary brain lesions metastasising to rib are even rarer still, there were no previous reports in the literature of synchronous brain and rib dual primary pathology that we could identify. Unrelated dual pathology, while rare, must be considered amongst the list of differential diagnoses in patients who present with multiple lesions, and highlights the importance of separate histological confirmation prior to integrated management.

Measurement of serum melatonin in intensive care unit patients: changes in traumatic brain injury, trauma, and medical conditions.

Melatonin is an endogenous hormone mainly produced by the pineal gland whose dysfunction leads to abnormal sleeping patterns. Changes in melatonin have been reported in acute traumatic brain injury (TBI); however, the impact of environmental conditions typical of the intensive care unit (ICU) has not been assessed. The aim of this study was to compare daily melatonin production in three patient populations treated at the ICU to differentiate the role of TBI versus ICU conditions. Forty-five patients were recruited and divided into severe TBI, trauma without TBI, medical conditions without trauma, and compared to healthy volunteers. Serum melatonin levels were measured at four daily intervals at 0400 h, 1000 h, 1600 h, and 2200 h for 7 days post-ICU admission by commercial enzyme linked immunosorbent assay. The geometric mean concentrations (95% confidence intervals) of melatonin in these groups showed no difference being 8.3 (6.3-11.0), 9.3 (7.0-12.3), and 8.9 (6.6-11.9) pg/mL, respectively, in TBI, trauma, and intensive care cohorts. All of these patient groups demonstrated decreased melatonin concentrations when compared to control patients. This study suggests that TBI as well as ICU conditions, may have a role in the dysfunction of melatonin. Monitoring and possibly substituting melatonin acutely in these settings may assist in ameliorating long-term sleep dysfunction in all of these groups, and possibly contribute to reducing secondary brain injury in severe TBI.