Handling Severe Intraoperative Hemorrhage and Avoiding Iatrogenic Stroke During Brain Tumor Surgery: Techniques for Prevention of Hemorrhagic and Ischemic Complications.

BACKGROUND: Nationwide databases show that iatrogenic stroke and postoperative hematoma are among the commonest complications in brain tumor surgery, with a 10-year incidence of 16.3/1000 and 10.3/1000, respectively. However, techniques for handling severe intraoperative hemorrhage and dissecting, preserving, or selectively obliterating vessels traversing the tumor are sparse in the literature. METHODS: Records of the senior author's intraoperative techniques during severe haemorrhage and vessel preservation were reviewed and analyzed. Intraoperative media demonstrations of key techniques were collected and edited. In parallel, a literature search investigating technique description in handling severe intraoperative hemorrhage and vessel preservation in tumor surgery was undertaken. Histologic, anesthetic, and pharmacologic prerequisites of significant hemorrhagic complications and hemostasis were analyzed. RESULTS: The senior author's techniques for arterial and venous skeletonization, temporary clipping with cognitive or motor mapping, and ION monitoring were categorized. Vessels interfacing with tumor are labeled intraoperatively as supplying/draining the tumor, or traversing en passant, while supplying/draining functional neural tissue. Intraoperative techniques of differentiation were analyzed and illustrated. Literature search found 2 vascular-related complication domains in tumor surgery: perioperative management of excessively vascular intraparenchymal tumors and lack of intraoperative techniques and decision processes for dissecting and preserving vessels interfacing or traversing tumors. CONCLUSIONS: Literature searches showed a dearth of complication-avoidance techniques in tumor-related iatrogenic stroke, despite its high prevalence. A detailed preoperative and intraoperative decision process was provided along with a series of case illustrations and intraoperative videos showing the techniques required to reduce intraoperative stroke and associated morbidity addressing a void in complication avoidance of tumor surgery.

Intraoperative stimulation mapping of thalamocortical tracts in asleep and awake settings: novel electrophysiological, anatomical, and tractographic paradigms.

OBJECTIVE: Despite the disabling deficits of motor apraxia and sensory ataxia resulting from intraoperative injury of the superior thalamocortical tracts (TCTs), region-specific electrophysiological localization is currently lacking. Herein, the authors describe a novel TCT mapping paradigm. METHODS: Three patients, 1 asleep and 2 awake, underwent glioma resection affecting primarily the somatosensory cortex and underlying TCT. Stimulation was performed at the median, ulnar, and posterior tibial nerves. Parameters comprised single anodal pulses (duration 200-500 µsec, 2.1-4.7 Hz) with a current ranging from 10 to 25 mA. Recordings were captured with a bipolar stimulation probe, avoiding the classic collision technique. Positive localization sites were used to tractographically reconstruct the TCT in the third case. RESULTS: Employing one electrophysiological paradigm, the TCT was localized subcortically in all 3 cases by using a bipolar probe, peak range of 19.6-29.2 msec, trough of 23.3-34.8 msec, stimulation range of 10-25 mA. In the last case, tractographic reconstruction of the TCT validated a highly accurate TCT localization within a specific region of the posterior limb of the internal capsule. CONCLUSIONS: The authors describe the first electrophysiological technique for intraoperative localization and protection of the TCT in both asleep and awake craniotomies with tractographic validation, while avoiding the collision paradigm. None of the above paradigms have been previously reported. More data are required to further validate this technique.

Resection of Ependymomas Infiltrating the Fourth Ventricular Floor: Anatomosurgical and Stimulation Mapping Techniques.

BACKGROUND: Despite the importance of complete, gross total resection (GTR) of fourth ventricular ependymomas, significant morbidity and/or subtotal resections are reported, particularly when the ventricular floor is infiltrated. Step-by-step technique descriptions are lacking in the literature. OBJECTIVE: To describe monitoring and stimulation mapping techniques and surgical nuances in the challenging subgroup of infiltrating fourth ventricular ependymomas by a highly illustrated, step-by-step description. Superimposed outlines of cranial nerve nuclei on the surgical field demonstrate critical anatomy and facilitate understanding in a way not previously presented. METHODS: We reviewed the microanatomical and neurophysiological prerequisites of resecting a diffusively infiltrating fourth ventricular ependymoma. RESULTS: We achieved GTR with the use of reproducible stimulating mapping and accurate cranial nerve nuclei identification. CONCLUSION: Enhanced microanatomical understanding, reproducible stimulation mapping, and meticulous resection techniques can result in GTR, even in diffusively infiltrating ependymomas.