Frameless robotically targeted stereotactic brain biopsy: feasibility, diagnostic yield, and safety

Robotics in keyhole transcranial endoscope-assisted microsurgery: a critical review of existing systems and proposed specifications for new robotic platforms

BACKGROUND

Over the past decade, advances in image guidance, endoscopy, and tube-shaft instruments have allowed for the further development of keyhole transcranial endoscope-assisted microsurgery, utilizing smaller craniotomies and minimizing exposure and manipulation of unaffected brain tissue. Although such approaches offer the possibility of shorter operating times, reduced morbidity and mortality, and improved long-term outcomes, the technical skills required to perform such surgery are inevitably greater than for traditional open surgical techniques, and they have not been widely adopted by neurosurgeons. Surgical robotics, which has the ability to improve visualization and increase dexterity, therefore has the potential to enhance surgical performance.

OBJECTIVE

To evaluate the role of surgical robots in keyhole transcranial endoscope-assisted microsurgery.

METHODS

The technical challenges faced by surgeons utilizing keyhole craniotomies were reviewed, and a thorough appraisal of presently available robotic systems was performed.

RESULTS

Surgical robotic systems have the potential to incorporate advances in augmented reality, stereoendoscopy, and jointed-wrist instruments, and therefore to significantly impact the field of keyhole neurosurgery. To date, over 30 robotic systems have been applied to neurosurgical procedures. The vast majority of these robots are best described as supervisory controlled, and are designed for stereotactic or image-guided surgery. Few telesurgical robots are suitable for keyhole neurosurgical approaches, and none are in widespread clinical use in the field.

CONCLUSION

New robotic platforms in minimally invasive neurosurgery must possess clear and unambiguous advantages over conventional approaches if they are to achieve significant clinical penetration.

Frameless image-guided stereotactic brain biopsies: emphasis on diagnostic yield

BACKGROUND

Studies regarding frameless stereotactic brain biopsy mainly report high diagnostic yield (DY) as opposed to relatively low diagnostic accuracy. This discrepancy raises the question of the certainty and precision of obtained diagnoses. This article proposes a DY definition encompassing diagnostic certainty and precision according to the World Health Organization (WHO) central nervous system (CNS) tumour classification system. Furthermore, our eight-year experience with this procedure is reviewed and evaluated.

METHODS

A consecutive series of 235 frameless biopsy procedures was reviewed. Criteria were set up for categorising obtained diagnoses. All cases were included in a predictive factor analysis of inconclusive biopsy and postoperative complications.

RESULTS

According to our predefined DY criteria, the DY was 72.8 %. The inconclusive biopsy outcome measured 21.7 %; the non-diagnostic biopsy outcome was 5.5 %. The only predictive factor found for inconclusive biopsy procedures was age under 30. Predictive factors for postoperative complications, which were found statistically significant after multivariable analysis, were glucose level and intra-operative haemorrhage. The total morbidity rate was 8.5 %, including a mortality rate of 0.9 %.

CONCLUSIONS

Although frameless stereotactic brain biopsy procedures are considered to be relatively safe, the true DY is significantly less than previously reported, most probably due to the lack of standardised DY criteria. Based on our DY definition and subsequent DY findings, standardisation of DY criteria and definition is paramount for biopsy diagnosis interpretation.

Current state-of-the-art and future perspectives of robotic technology in neurosurgery

Neurosurgery is one of the most demanding surgical specialties in terms of precision requirements and surgical field limitations. Recent advancements in robotic technology have generated the possibility of incorporating advanced technological tools to the neurosurgical operating room. Although previous studies have addressed the specific details of new robotic systems, there is very little literature on the strengths and drawbacks of past attempts, currently available platforms and prototypes in development. In this review, the authors present a critical historical analysis of the development of robotic technology in neurosurgery as well as a comprehensive summary of the currently available systems that can be expected to be incorporated to the neurosurgical armamentarium in the near future. Finally, the authors present a critical analysis of the main technical challenges in robotic technology development at the present time (such as the design of improved systems for haptic feedback and the necessity of incorporating intraoperative imaging data) as well as the benefits which robotic technology is expected to bring to specific neurosurgical subspecialties in the near future.

Robot-Assisted Stereotactic Laser Ablation in Medically Intractable Epilepsy: Operative Technique

BACKGROUND:

Stereotactic laser ablation offers an advantage over open surgical procedures for treatment of epileptic foci, tumors, and other brain pathology. Robot-assisted stereotactic laser ablation could offer an accurate, efficient, minimally invasive, and safe method for placement of an ablation catheter into the target.

OBJECTIVE:

To determine the feasibility of placement of a stereotactic laser ablation catheter into a brain lesion with the use of robotic assistance, via a safe, accurate, efficient, and minimally invasive manner.

METHODS:

A laser ablation catheter (Visualase, Inc) was placed by using robotic guidance (ROSA, Medtech Surgical, Inc) under general anesthesia into a localized epileptogenic periventricular heterotopic lesion in a 19-year-old woman with 10-year refractory focal seizure history. The laser applicator (1.65 mm diameter) position was confirmed by using magnetic resonance imaging (MRI). Ablation using the Visualase system was performed under multiplanar imaging with real-time thermal imaging and treatment estimates in each plane. A postablation MRI sequence (T1 postgadolinium contrast injection) was used to immediately confirm the ablation.

RESULTS:

MRI showed accurate skin entry point and trajectory, with the applicator advanced to the lesion's distal boundary. Ablation was accomplished in less than 3 minutes of heating. The overall procedure, from time of skin incision to end of last ablation, was approximately 90 minutes. After confirmation of proper lesioning by using a T1 contrast-enhanced MRI, the applicator was removed, and the incision was closed using a single stitch. No hemorrhage or other untoward complication was visualized. The patient awoke without any complication, was observed overnight after admitting to a regular floor bed, and was discharged to home the following day.

CONCLUSION:

This technique, using a combination of Visualase laser ablation, ROSA robot, and intraoperative MRI, facilitated a safe, efficacious, efficient, and minimally invasive approach that could be used for placement of 1 or multiple electrodes in the future.

Bifocal intracranial tumors of nongerminomatous germ cell etiology: diagnostic and therapeutic implications

BACKGROUND

Patients presenting with synchronous bifocal intracranial tumors (masses in the pineal and neurohypophyseal region), detectable human chorionic gonadotropin (hCG) levels (5-100 mIU/mL), and normal alpha feto-protein (AFP) levels (≤10 ng/mL) are often diagnosed empirically with pure germinoma. In such scenarios, pathologic confirmation is often deferred, given that bifocal nongerminomatous germ cell tumors (NGGCTs) are considered rare and because available literature and research protocols support such an approach. We sought to characterize the association between bifocal intracranial tumors and NGGCT histology.

METHODS

Seventy-one patients treated for intracranial germ cell tumors at Massachusetts General Hospital in 1998-2012 were identified. Patients presenting with synchronous bifocal disease were selected for further review.

RESULTS

Of the 71 patients presenting with intracranial germ cell tumors, 14 (19.7%) had synchronous bifocal disease. Of these 14 patients, 7 (50.0%) had germinoma, 3 (21.4%) had NGGCT, and 4 (28.6%) had hCG levels <200 mIU/mL and normal AFP levels and were treated without pathologic confirmation. Of the 3 patients with confirmed bifocal NGGCT, 2 had detectable hCG levels with AFP <10 ng/mL and 1 patient had a detectable hCG level with a modest elevation in AFP.

CONCLUSIONS

NGGCTs should be considered in the differential diagnosis for patients presenting with bifocal intracranial tumors. Given differences in the management of germinomas and NGGCTs, clinicians should strongly consider a biopsy in patients presenting with bifocal masses and normal or modestly elevated biomarkers. Misclassification of such cases as germinomas could result in undertreatment and a possible increased risk for recurrence.