Technical report: surgical preparation of human brain tissue for clinical and basic research

BACKGROUND

The study of the distinct structure and function of the human central nervous system, both in healthy and diseased states, is becoming increasingly significant in the field of neuroscience. Typically, cortical and subcortical tissue is discarded during surgeries for tumors and epilepsy. Yet, there is a strong encouragement to utilize this tissue for clinical and basic research in humans. Here, we describe the technical aspects of the microdissection and immediate handling of viable human cortical access tissue for basic and clinical research, highlighting the measures needed to be taken in the operating room to ensure standardized procedures and optimal experimental results.

METHODS

In multiple rounds of experiments (n = 36), we developed and refined surgical principles for the removal of cortical access tissue. The specimens were immediately immersed in cold carbogenated N-methyl-D-glucamine-based artificial cerebrospinal fluid for electrophysiology and electron microscopy experiments or specialized hibernation medium for organotypic slice cultures.

RESULTS

The surgical principles of brain tissue microdissection were (1) rapid preparation (<1 min), (2) maintenance of the cortical axis, (3) minimization of mechanical trauma to sample, (4) use of pointed scalpel blade, (5) avoidance of cauterization and blunt preparation, (6) constant irrigation, and (7) retrieval of the sample without the use of forceps or suction. After a single round of introduction to these principles, multiple surgeons adopted the technique for samples with a minimal dimension of 5 mm spanning all cortical layers and subcortical white matter. Small samples (5-7 mm) were ideal for acute slice preparation and electrophysiology. No adverse events from sample resection were observed.

CONCLUSION

The microdissection technique of human cortical access tissue is safe and easily adoptable into the routine of neurosurgical procedures. The standardized and reliable surgical extraction of human brain tissue lays the foundation for human-to-human translational research on human brain tissue.

Piezosurgery for safe and efficient petrous bone cutting in cerebellopontine angle and petroclival meningioma surgery

Intradural petrous bone drilling has become a widespread practice, providing extended exposure in the removal of cerebellopontine angle (CPA) or petroclival tumors. Adjacent neurovascular structures are at risk, however, when drilling is performed in this deep and narrow area. Hence, this study evaluates the use of Piezosurgery (PS) as a non-rotating tool for selective bone cutting in CPA surgery. A Piezosurgery® device was used in 36 patients who underwent microsurgery for extra-axial CPA or petroclival tumors in our Neurosurgical Department between 2013 and 2019. The clinical and radiological data were retrospectively analyzed. The use of PS was evaluated with respect to the intraoperative applicability and limitations as well as efficacy and safety of the procedure. Piezosurgical petrous bone cutting was successfully performed in the removal of meningiomas or extra-axial metastases arising from the dura of the petroclival region (21 patients) or petrous bone (15 patients). PS proved to be very helpful in the deep and narrow CPA region, considerably reducing the surgeon's distress toward bone removal in close proximity to cranial nerves and vessels in comparison to common rotating drills. The use of PS was safe without injuries to neurovascular structures. Gross total resection was achieved in 67% of petroclival and 100% of petrous bone tumors. Piezosurgery proved to be an effective and safe method for selective petrous bone cutting in CPA surgery avoiding rotating power and associated risks. This technique can particularly be recommended for bone cutting in close vicinity to critical neurovascular structures.

Facet-Sparing Decompression of Lumbar Spinal Stenosis: The Minimally Invasive Bilateral Crossover Approach

BACKGROUND AND STUDY OBJECTIVE

 One risk of established decompression techniques for lumbar spinal stenosis is the resection of facet joints, especially if they are steeply configured, promoting destabilization. Minimally invasive bilateral crossover decompression aims to preserve the facet joints and thus stability of the spine. The purpose of this study is to demonstrate the feasibility and early results of this technique.

METHODS

 This retrospective case series includes 10 consecutive patients with lumbar stenosis and steep-angle (<35 degrees) facet joints who were treated with minimally invasive bilateral crossover decompression. Eleven segments were decompressed, most commonly L3/L4 (63.6%), followed by L1/L2 and L2/L3 (18.2% each). The effectiveness of surgical decompression was assessed by self-reporting questionnaires.

RESULTS

 After a follow-up of 10.5 months, the Symptom Severity Scale and Physical Function Scale of the Swiss Spinal Stenosis Questionnaire improved by 0.9 (p < 0.05) and 0.7 points, respectively. The mean Oswestry Disability Index improved from 53.9 to 34.6 (p < 0.05). Local and radiating pain under strain showed statistically significant improvement on the Visual Analog Scale (8.9 vs. 5.0 and 8.4 vs. 4.6, respectively). Maximum walking distance increased from 190 to 1,029 m. Apart from one patient requiring surgical decompression of an adjacent segment, there were no reoperations, neurological deteriorations, or other complications.

CONCLUSION

 The results of this study indicate that minimally invasive bilateral crossover decompression is a promising technique for the treatment of spinal canal stenosis. With its design to spare facet joints, it can potentially reduce the risk of spinal instability, especially in patients with steep facet joints.