A Stereotactic Device for Intraparenchymal Spinal Cord Injections: Latest Developments for Practical Clinical Use

This manuscript introduces the latest generation of a patient-mounted platform designed for segmental injections of therapeutics direct into the spinal cord parenchyma. It emphasizes its importance and it presents the rationale for developing this delivery methodology. It compares the newest with the previous generations, detailing how the modifications can streamline transportation, assembly, sterilization, and utilization of the platform by different surgeons. Finally, the illustrations depict the main alterations, as well as a cadaveric assessment of the device prototype in the cervical and thoracolumbar regions.

An Overview of Robotics in Functional Neurosurgery

Stereotactic techniques are used in a wide range of neurosurgical procedures. The procedures demand a high degree of spatial accuracy and minimal error. There are diverse functional surgeries that require stereotactic procedures, including deep brain stimulation, brain biopsies, and epilepsy procedures. Though the disease processes are diverse, all these procedures require accurate targeting of deep structures without visual guidance. The use of robots for stereotactic procedures is a natural progression in the surgeon's quest for higher accuracy and lower complications. This paper reviews the role of robots in stereotactic procedures and outlines current status of robots in stereotactic procedures. The shortcomings of current systems and an outline of an ideal stereotactic device are presented.

Geoffrey Knight and his contribution to psychosurgery

This paper retraces the fundamental achievements of Geoffrey Knight (1906–1994), a British neurosurgeon and a pioneer in the field of psychosurgery. His career developed in the 1950s and 1960s, when—following the unregulated practice of frontal lobotomies—strong criticism arose in the medical community and in the general public against psychosurgery. Geoffrey Knight's clinical research focused on identifying new, selective targets to limit the side effects of psychosurgery while improving the outcome of patients affected by mental disorders. Following the example of William Beecher Scoville, he initially developed restricted orbital undercutting as a less invasive alternative to standard frontal lobotomy. He then developed stereotactic subcaudate tractotomy, with the use of an original stereotactic device. Knight stressed the importance of the anatomy and neurophysiology of the structures targeted in subcaudate tractotomy, with particular regard to the fibers connecting the anterior cingulate region, the amygdala, the orbitofrontal cortex, and the hypothalamus. Of interest, the role of these white matter connections has been recently recognized in deep brain stimulation for major depression and anorexia nervosa. This is perhaps the most enduring legacy of Knight to the field of psychosurgery. He refined frontal leucotomies by selecting a restricted target at the center of a network that plays a crucial role in controlling mood disorders. He then developed a safe, minimally invasive stereotactic operation to reach this target. His work, well ahead of his time, still represents a valid reference on which to build future clinical experience in the modern era of neuromodulation for psychiatric diseases.

Safety of stereotactic laser ablations performed as treatment for glioblastomas in a conventional magnetic resonance imaging suite

OBJECTIVE Stereotactic laser ablation (SLA) is typically performed in the setting of intraoperative MRI or in a staged manner in which probe insertion is performed in the operating room and thermal ablation takes place in an MRI suite. METHODS The authors describe their experience, in which SLA for glioblastoma (GBM) treatment was performed entirely within a conventional MRI suite using the SmartFrame stereotactic device. RESULTS All 10 patients with GBM (2 with isocitrate dehydrogenase 1 mutation [mIDH1] and 8 with wild-type IDH1 [wtIDH1]) were followed for > 6 months. One of these patients underwent 2 independent SLAs approximately 12 months apart. Biopsies were performed prior to SLA for all patients. There were no perioperative morbidities, wound infections, or unplanned 30-day readmissions. The average time for a 3-trajectory SLA (n = 3) was 436 ± 102 minutes; for a 2-trajectory SLA (n = 4) was 321 ± 85 minutes; and for a single-trajectory SLA (n = 4) was 254 ± 28 minutes. No tumor recurrence occurred within the blue isotherm line ablation zone, although 2 patients experienced recurrence immediately adjacent to the blue isotherm ablation line. Overall survival for the patient cohort averaged 356 days, with the 2 patients who had mIDH1 GBMs exhibiting the longest survival (811 and 654 days). CONCLUSIONS Multitrajectory SLA for treatment of GBM can be safely performed using the SmartFrame stereotactic device in a conventional MRI suite.

Comparative Analysis of the Retrosigmoid and Lateral Supracerebellar Infratentorial Approaches along the Lateral Surface of the Pontomesencephalic Junction: A Different Perspective

Objective: To quantitatively assess the working distance and angle of attack among the retrosigmoid (RS), lateral supracerebellar (LS), and extreme lateral supracerebellar (EL) views on the lateral surface of the pontomesencephalic junction. Methods: Eight sides of silicone-injected fixed cadaveric heads were dissected using the three approaches. All predetermined anatomic points were collected by use of a frameless stereotactic device. The length of exposure and the angle of attack were calculated and compared. Predissection imaging was obtained for illustration. Results: The LS and EL approaches created a horizontal working space as compared with the vertical working space created by the RS approach. The RS view gained less posterior exposure margin than the LS and EL views (posterosuperior margin values: RS, 4.3 ± 1.7 mm; LS, 6.4 ± 2.0 mm; EL, 7.3 ± 2.0 mm; P < 0.001; posteroinferior margin: RS, 2.7 ± 2.7 mm; LS, 4.9 ± 2.8 mm; EL, 8.3 ± 2.5 mm; P < 0.001). When the tentorium is intact, transverse sinus retraction significantly accentuates the field of view by the EL approach compared with the LS approach at both the anteroinferior (P < 0.05) and posteroinferior (P < 0.001) margins. Between the supracerebellar types, the vertical angle of attack was significantly improved and the horizontal angle was significantly decreased when complete venous retraction was performed. Conclusion: The supracerebellar views offer greater advantage over the RS view when the surgeon is working more posteriorly on the pontomesencephalic junction. Between the supracerebellar views, venous retraction creates a significantly wider vertical angle and also improves the exposure when the surgeon is working more inferiorly.

A stereotactic device for rabbits based on mandibular and cranial landmarks

✓ The authors have developed a stereotactic device for use in rabbits that uses the plane at the base of the mandible combined with cranial sutures as an anatomical reference. The device was developed for a study designed to evaluate catheters for infection prophylaxis, and this required the implantation of silicone catheters along a reproducible trajectory through the lateral ventricle. Cadaver and atlas studies demonstrated consistent spatial relationships between intracranial structures and the surface plane on which the animals were resting during the surgery. This plane is formed by the 2 mandibular angles and the mandibular tip. The authors developed a stainless steel stereotactic device that uses this mandibular plane as well as the coronal and sagittal sutures as spatial references. Operations were performed in 60 animals using the stereotactic device, and postmortem dissections of the animals' brains demonstrated 78.6% accuracy of the trajectory within a tolerance of deviation of 5°, and 94.6% accuracy within a tolerance of 10°. The accuracy of the trajectory of the last 18 consecutively operated animals was constantly within a tolerance of 5°. The device can be autoclaved and, since it is relatively simple and inexpensive to build, the authors manufactured 3 identical frames and used them alternately to operate under sterile conditions. The fast and pain-free head fixation minimized anesthesia-related risks. The authors' experiences suggest that the device is suitable for ventricular punctures and, dependant on the individual requirements of accuracy, other procedures that require “approximate” stereotactic guidance especially when a series of animals need to undergo operations quickly.