A New Noninvasive Frameless Registration System for Stereotactic Cranial Biopsy

 Operative Neurosurgery 24:64–67, 2023

Although frame-based stereotactic biopsy is still considered the gold standard for brain biopsies, frameless robot-assisted stereotactic systems are now able to provide an equal level of safety and accuracy. However, both systems suffer from a lack of efficiency of the operative workflow.

OBJECTIVE: To describe the technique of a new frameless and noninvasive registration tool Neurolocate (Renishaw). This tool, combined with an intraoperative cone-beam computed tomography imaging system like O-ARM (Medtronic), might facilitate the achievement and workflow of robot-assisted stereotactic intracranial biopsies.

METHODS: Neurolocate is a 3-dimensional fiducial tool fixed directly on the Neuromate (Renishaw) robot arm. It consists of 5 radio-opaque spherical fiducials, whose geometry is constant. This tool made it possible to carry out the coregistration then the biopsy in the same operating time, following a five-step procedure described here. We retrospectively extracted selected preliminary results from our initial experience.

RESULTS: Over 1 year, 23 consecutive adult patients were biopsied with Neurolocate in our center. The mean overall operative time, from patient’s installation to skin closure, was 97 minutes ± 27 (SD). The entire procedure took place in a single location unit (operating room), which facilitated workflow and surgical planning. No invasive gesture was performed outside of the operating time.

CONCLUSION: Neurolocate is a new frameless and noninvasive registration tool that could improve workflow and flexibility for operating room management and surgical planning. It may also increase the comfort of patients undergoing robot-assisted intracranial stereotactic biopsies. The accuracy and safety profile should be addressed in specific studies.


A novel use of cone beam CT: flexion and extension weight‑bearing imaging to assess spinal stability

European Spine Journal (2022) 31:1667–1681

Purpose To assess spinal stability in different physiological positions whilst weight-bearing.

Methods A cone beam CT scanner (CBCT) was used to identify any abnormal motion in the spine in different physiological positions whilst weight-bearing. The lumbar spine was assessed in 6 different patients with a comfortable neutral standing position and standing flexion and extension images in selected patients. Seated, weight-bearing flexion and extension images of the cervical spine were obtained in a further patient. Clinical indications included stability assessment post-trauma, post-surgical fusion and back pain. The projection images were reconstructed using bone and soft tissue algorithms to give isotropic CT images which could be viewed as per conventional multi-detector CT images. The flexion and extension CBCT data were fused to give a representation of any spinal movement between the extremes of motion.

Results The flexion and extension weight-bearing images gave anatomical detail of the spine. Detail of the surgical constructs was possible. Dynamic structural information about spinal alignment, facet joints, exit foramina and paraspinal musculature was possible. The effective dose from the neutral position was equal to that of supine, multi-detector CT.

Conclusion CBCT can be used to image the lumbar and cervical spine in physiological weight-bearing positions and at different extremes of spinal motion. This novel application of an existing technology can be used to aid surgical decision making to assess spinal stability and to investigate occult back and leg pain. Its use should be limited to specific clinical indications, given the relatively high radiation dose.

Predictors of postoperative motor function in rolandic meningiomas

J Neurosurg 130:1283–1288, 2019

Resection of supratentorial meningiomas is generally considered a low-risk procedure, but tumors involving the rolandic cortex present a unique challenge. The rate of motor function deterioration associated with resecting such tumors is not well described in the literature. Thus, the authors sought to report the rates and predictors of postoperative motor deficit following the resection of rolandic meningiomas to assist with patient counseling and surgical decision-making.

METHODS An institution’s pathology database was screened for meningiomas removed between 2000 and 2017, and patients with neuroradiological evidence of rolandic involvement were identified. Parameters screened as potential predictors included patient age, sex, preoperative motor severity, tumor location, tumor origin (falx vs convexity), histological grade, FLAIR signal (T2-weighted MRI), venous involvement (T1-weighted MRI with contrast), intratumoral hemorrhage, embolization, and degree of resection (Simpson grade). Variables of interest included preoperative weakness and postoperative motor decline (novel or worsened permanent deficit). The SPSS univariate and bivariate analysis functions were used, and statistical significance was determined with alpha < 0.05.

RESULTS In 89 patients who had undergone resection of convexity (80.9%) or parasagittal (19.1%) rolandic meningiomas, a postoperative motor decline occurred in 24.7%. Of 53 patients (59.6%) with preoperative motor deficits, 60.3% improved, 13.2% were unchanged, and 26.4% worsened following surgery. Among the 36 patients without preoperative deficits, 22.2% developed new weakness. Predictors of preoperative motor deficit included tumor size (41.6 vs 33.2 cm3, p = 0.040) and presence of FLAIR signal (69.8% vs 50.0%, p = 0.046). Predictors of postoperative motor decline were preoperative motor deficit (47.2% vs 22.2%, p = 0.017), minor (compared with severe) preoperative weakness (25.6% vs 21.4%, p < 0.001), and preoperative embolization (54.5% vs 20.5%, p = 0.014). Factors that trended toward significance included parafalcine tumor origin (41.2% vs 20.8% convexity, p = 0.08), significant venous involvement (44.4% vs 23.5% none, p = 0.09), and Simpson grade II+ (34.2% vs 17.6% grade I, p = 0.07).

CONCLUSIONS Resection of rolandic area meningiomas carries a high rate of postoperative morbidity and deserves special preoperative planning. Large tumor size, peritumoral edema, preoperative embolization, parafalcine origin, and venous involvement may further increase the risk. Alternative surgical strategies, such as aggressive internal debulking, may prevent motor decline in a subset of high-risk patients.


The behavior of residual tumors and facial nerve outcomes after incomplete excision of vestibular schwannomas

 incomplete excision of vestibular schwannomas

J Neurosurg 120:1278–1287, 2014

The authors evaluated the behavior of residual tumors and facial nerve outcomes after incomplete excision of vestibular schwannomas (VSs).

Methods. The case records of all patients who underwent surgical treatment of VSs were analyzed. All patients in whom an incomplete excision had been performed were analyzed. Incomplete excision was defined as near-total resection (NTR), subtotal resection (STR), and partial resection (PR). Tumors in the NTR and STR categories were followed up with a wait-and-rescan approach, whereas the tumors in the PR category were subjected to a second- stage surgery and were excluded from this series. All patients included in the study underwent baseline MRI at the 3rd and 12th postoperative months, and repeat imaging was subsequently performed every year for 7–10 years postoperatively or as indicated clinically. Preoperative and postoperative facial function was noted.

Results. Of the 2368 patients who underwent surgery for VS, 111 patients who had incomplete excisions of VSs were included in the study. Of these patients, 73 (65.77%) had undergone NTR and 38 (34.23%) had undergone STR. Of the VSs, 62 (55.86%) were cystic and 44 (70.97%) of these cystic VSs underwent NTR. The residual tumor was left behind on the facial nerve alone in 62 patients (55.86%), on the facial nerve and vessels in 2 patients (1.80%), on the facial nerve and brainstem in 15 patients (13.51%), and on the brainstem alone in 25 patients (22.52%). In the 105 patients with normal preoperative facial nerve function, postoperative facial nerve function was House-Brackmann (HB) Grades I and II in 51 patients (48.57%), HB Grade III in 34 patients (32.38%), and HB Grades IV–VI in 20 pa- tients (19.05%). Seven patients (6.3%) showed evidence of tumor regrowth on follow-up MRI. All 7 patients (100%) who showed evidence of tumor regrowth had undergone STR. No patient in the NTR group exhibited regrowth. The Kaplan-Meier plot demonstrated a 5-year tumor regrowth-free survival of 92%, with a mean disease-free interval of 140 months (95% CI 127–151 months). The follow-up period ranged from 12 to 156 months (mean 45.4 months).

Conclusions. The authors’ report and review of the literature show that there is undoubtedly merit for NTR and STR for preservation of the facial nerve. On the basis of this they propose an algorithm for the management of incomplete VS excisions. Patients who undergo incomplete excisions must be subjected to follow-up MRI for a period of at least 7–10 years. When compared with STR, NTR via an enlarged translabyrinthine approach has shown to have a lower rate of regrowth of residual tumor, while having almost the same result in terms of facial nerve function.



Percutaneous trigeminal tractotomy–nucleotomy with use of intraoperative computed tomography and general anesthesia

Percutaneous trigeminal tractotomy–nucleotomy with use of

Neurosurg Focus 35 (3):E5, 2013

For confirming the correct location of the radiofrequency electrode before creation of a lesion, percutaneous CT-guided trigeminal tractotomy–nucleotomy is most commonly performed with the patient prone and awake. However, for patients whose facial pain and hypersensitivity are so severe that the patients are unable to rest their face on a support (as required with prone positioning), awake CT-guided tractotomy-nucleotomy might not be feasible.

The authors describe 2 such patients, for whom percutaneous intraoperative CT-guided tractotomy-nucleotomy under general anesthesia was successful. One patient was a 79-year-old man with profound left facial postherpetic neuralgia, who was unable to tolerate awake CT-guided tractotomy-nucleotomy, and the other was a 45-year-old woman with intractable hemicranial pain that developed after a right frontal lesionectomy for epilepsy. Each patient underwent a percutaneous intraoperative CT-guided tractotomy-nucleotomy under general anesthesia.

No complications occurred, and each patient reported excellent pain relief for up to 6 and 3 months after surgery, respectively. Percutaneous intraoperative CT-guided tractotomy-nucleotomy performed on anesthetized patients is effective for facial postherpetic neuralgia and postoperative hemicranial neuralgia

Flat-Panel Fluoroscopy O-arm–Guided Percutaneous Radiofrequency Cordotomy: A New Technique for the Treatment of Unilateral Cancer Pain

O-arm cordotomy

Neurosurgery 72[ONS Suppl 1]:ons27–ons34, 2013

Percutaneous radiofrequency cordotomy (PRFC) involves controlled ablation of the anterolateral quadrant of the spinal cord, thereby relieving pain. Evolving from a morbid open surgery, the procedure has been modernized through the application of physiological target confirmation, well-regulated thermal ablation, and improved intraoperative imaging.

OBJECTIVE: To evaluate the utility in PRFC of a new high-resolution, portable flatpanel fluoroscopic imaging technology, the O-arm Imaging System. The O-arm allows traditional 2-dimensional fluoroscopy in addition to axial and 3-dimensional reconstructed computed tomography imaging.

METHODS: PRFC was performed using the O-arm Imaging System in 6 patients with unilateral cancer pain.

RESULTS: Patients experienced 90% to 100% initial pain relief, with 50% to 100% sustained pain relief at the time of death at 2 to 12 months. There were no complications.

CONCLUSION: Portable flat-panel fluoroscopy allows high-resolution, readily updated computed tomography and fluoroscopic image guidance during PRFC. Use of this new technology may assist neurosurgeons in providing an important analgesic intervention at centers possessing the imaging technology.


The Use of Intraoperative Navigation for Percutaneous Procedures at the Skull Base Including a Difficult-to-Access Foramen Ovale

Neurosurgery 70[ONS Suppl 2]:ons177–ons180, 2012 DOI: 10.1227/NEU.0b013e3182309448

We describe the use of an intraoperative CT scan obtained using the Medtronic O-arm (Littleton, Massachusetts) for image-guided cannulation of the foramen ovale not previously accessible with the use of fluoroscopy alone. Unlike previously described procedures, this technique does not require placement of an invasive head clamp and may be used with an awake patient.

OBJECTIVE: To describe the use of intraoperative neuronavigation for accessing skull base foramina and, specifically, cannulating of the foramen ovale during percutaneous rhizotomy procedures using an intraoperative image guidance CT scanner (Medtronic O-arm, Littleton, Massachusetts).

METHODS: A noninvasive Landmark Fess Strap attached to a spine reference frame was applied to the heads of 4 patients who harbored a difficult-to-access foramen ovale. An intraoperative HD3D skull base scan using a Medtronic O-arm was obtained, and Synergy Spine software was used to create 3D reconstructions of the skull base. Using image guidance, we navigated the needle to percutaneously access the foramen ovale by the use of a single tract for successful completion of balloon compression of the trigeminal nerve.

RESULTS: All 4 patients (3 females and 1 male; ages 65-75) underwent the procedure with no complications.

CONCLUSION: Based on our experience, neuronavigation with the use of intraoperative O-arm CT imaging is useful during these cases.

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