Intraoperative continuous vagus nerve monitoring with repetitive direct stimulation in surgery for jugular foramen tumors

Stereotactic Radiosurgery and Surgical Resection for Jugular Foramen Schwannomas: A Retrospective Comparative Study of Outcomes

BACKGROUND AND OBJECTIVES

Jugular foramen schwannomas (JFS) are rare benign tumors arising from lower cranial nerves. In this study, we aim to compare the outcomes of surgical resection (SR) and stereotactic radiosurgery (SRS) in the treatment of JFS.

METHODS

We conducted a retrospective analysis of 31 patients with JFS who underwent SRS (13 patients [41.9%]) or surgical resection (18 patients [58.1%]) as their primary management modality over a two-decade period. Outcomes included progression-free survival, post-treatment adverse events based on Common Terminology Criteria for Adverse Events, symptom improvement, overall survival, and the necessity for secondary interventions. Local tumor control was also evaluated in all patients who received SRS.

RESULTS

Significant differences were observed in baseline characteristics between the SRS and SR groups, including median age (58 vs 48 years, P = .001), largest tumor diameter (32.0 vs 47.5 mm, P = .02), and total tumor volume (6.50 vs 20.5 mm3, P = .01). There were no significant differences in sex or lesion morphology (dumbbell vs nondumbbell shaped). After adjusting for baseline characteristics, no significant differences were noted in progression-free survival (90.9 vs 86.2%), overall survival (92.3 vs 100%), symptom improvement (61.5 vs 55.5%), or median Common Terminology Criteria for Adverse Events grade (1 in both groups) between the SRS and SR groups, respectively. SRS patients had significantly lower odds of requiring secondary treatment procedures after their primary intervention as compared with those who underwent SR (odds ratio = 0.02, 95% CI: 0.001-0.88, P-value = .04). Local tumor control in all SRS patients (19 patients) was 93.7% and 79.1% at six-month and five-year time points, respectively.

CONCLUSION

SRS and SR demonstrate comparable effectiveness in treating JFS. However, SRS may be a more favorable option because of a reduced need for secondary interventions. Future controlled prospective studies are needed to draw more definitive conclusions.

Post-surgical Hearing Improvement in a Case of Jugular Foramen Schwannoma Despite the Lack of Response in a Preoperative Auditory Brainstem Response Test

We report a rare case involving improved hearing after surgery for a jugular foramen schwannoma despite the lack of response during the preoperative auditory brainstem response (ABR) test. A left jugular foramen tumor was diagnosed in a 79-year-old man with hearing loss. No response was observed during the preoperative ABR test. However, his hearing improved after surgery using the lateral suboccipital approach. Following Gamma Knife radiation to the residual tumor post-surgery, the ABR test detected V waves. The hearing of patients with cerebellopontine angle tumors can improve even when there is no response during the preoperative ABR test.

Automated algorithm aided capacity and confidence boost in surgical decision-making training for inferior clivus

Objective

To assess the impact of automated algorithms on the trainees' decision-making capacity and confidence for individualized surgical planning.

Methods

At Chinese PLA General Hospital, trainees were enrolled to undergo decision-making capacity and confidence training through three alternative visual tasks of the inferior clivus model formed from an automated algorithm and given consecutively in three exemplars. The rationale of automated decision-making was used to instruct each trainee.

Results

Following automated decision-making calculation in 50 skull base models, we screened out three optimal plans, infra-tubercle approach (ITA), trans-tubercle approach (TTA), and supra-tubercle approach (STA) for 41 (82.00%), 8 (16.00%), and 1 (2.00%) subject, respectively. From September 1, 2023, through November 17, 2023, 62 trainees (median age [range]: 27 [26-28]; 28 [45.16%] female; 25 [40.32%] neurosurgeons) made a decision among the three plans for the three typical models (ITA, TTA, and STA exemplars). The confidence ratings had fine test-retest reliability (Spearman's rho: 0.979; 95% CI: 0.970 to 0.988) and criterion validity with time spent (Spearman's rho: -0.954; 95%CI: -0.963 to -0.945). Following instruction of automated decision-making, time spent (initial test: 24.02 vs. 7.13 in ITA; 30.24 vs. 7.06 in TTA; 34.21 vs. 12.82 in STA) and total hits (initial test: 30 vs. 16 in ITA; 37 vs. 17 in TTA; 42 vs. 28 in STA) reduced significantly; confidence ratings (initial test: 2 vs. 4 in ITA; 2 vs. 4 in TTA; 1 vs. 3 in STA) increased correspondingly. Statistically significant differences (P < 0.05) were observed for the above comparisons.

Conclusions

The education tool generated by automated decision-making considers surgical freedom and injury risk for the individualized risk-benefit assessment, which may provide explicit information to increase trainees' decision-making capacity and confidence.

Navigated Transcranial Magnetic Stimulation (nTMS) based Preoperative Planning for Brain Tumor Treatment

Transcranial Magnetic Stimulation (TMS) is a non-invasive technique for analyzing the central and peripheral nervous system. TMS could be a powerful therapeutic technique for neurological disorders. TMS has also shown potential in treating various neurophysiological complications, such as depression, anxiety, and obsessive-compulsive disorders, without pain and analgesics. Despite advancements in diagnosis and treatment, there has been an increase in the prevalence of brain cancer globally. For surgical planning, mapping brain tumors has proven challenging, particularly those localized in expressive regions. Preoperative brain tumor mapping may lower the possibility of postoperative morbidity in surrounding areas. A navigated TMS (nTMS) uses magnetic resonance imaging (MRI) to enable precise mapping during navigated brain stimulation. The resulting magnetic impulses can be precisely applied to the target spot in the cortical region by employing nTMS. This review focuses on nTMS for preoperative planning for brain cancer. This study reviews several studies on TMS and its subtypes in treating cancer and surgical planning. nTMS gives wider and improved dimensions of preoperative planning of the motor-eloquent areas in brain tumor patients. nTMS also predicts postoperative neurological deficits, which might be helpful in counseling patients. nTMS have the potential for finding possible abnormalities in the motor cortex areas.

Telovelar/Transcerebellomedullary Fissure Approach: Giant Distal Posterior Inferior Cerebellar Artery Aneurysm, Epidermoid Cyst, and Brainstem Cavernoma: 2-Dimensional Operative Video

INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE

The telovelar or transcerebellomedullary fissure approach can provide wide exposure of the cerebellomedullary fissure and fourth ventricle by separating the natural plane between the medulla and cerebellum. 1-5.

ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT

The cerebellar tonsil is attached to the adjacent cerebellum only by the tonsillar peduncle at its superolateral edge. 2 The posterior inferior cerebellar artery (PICA) runs in the cerebellomedullary fissure, usually making its caudal and cranial loops. 6,7.

ESSENTIALS STEPS OF THE PROCEDURE

After widely opening the foramen magnum, the tonsil is gently elevated by shearing the tela choroidea up to the lateral recess from the taenia, where the vein of the inferior cerebellar peduncle courses. 8,9.

PITFALLS/AVOIDANCE OF COMPLICATIONS

The developed occipital sinus, posterior condylar vein, and anomalies of the vertebral artery and PICA origin can obstruct the exposure. Detailed neuromonitoring is essential for accomplishing the procedure safely. 10,11.

VARIANTS AND INDICATIONS FOR THEIR USE

This exposure can be extended to the lower cerebellopontine angle and can also be applied to the dorsal brainstem surgery. 2,12 The patients consented to the procedure and to the publication of their images.Image Credits: Department of Neurosurgery, Tokyo Medical University logo used by permission. Image at 0:10, 1:02, 2:46, 6:22, and 7:10 from Matsushima and Kohno, 1 used by permission from Medical View Co., Ltd.Right image at 0:14 and also upper image at 0:46, image at 1:26, and for left and lower right images at 1:54 from Matsushima et al, 2 by permission from Journal of Neurosurgery Publishing Group (JNSPG). Left image at 0:14, from Matsushima et al, 4 used by permission from the Congress of Neurological Surgeons. Lower image at 0:46 reprinted from Matsushima et al, 9 by permission from Elsevier. Left image at 1:06 from Matsushima et al, 8 used by permission from the Congress of Neurological Surgeons.Image at top right at 1:54 from Lister et al, 6 used by permission from the Congress of Neurological Surgeons. Image in center at 6:56 from Matsushima et al, 11 used by permission from Springer Nature. Image at right at 6:56 from Matsushima et al, 10 used by permission from JNSPG. Images at 9:48, by year: 1982 article screenshot and figure from Matsushima et al, 4 by permission from the Congress of Neurological Surgeons; 1992: article title screenshot from Matsushima et al, 3 by permission from the Congress of Neurological Surgeons; 1996: used with permission of McGraw-Hill Health Professions Division, from Microsurgical Anatomy of the Fourth Ventrical, Matshushiam T and Rhoton AL Jr, in Neurosurgery , eds Wilkins and Rengachary, vol 1, 1996, permission conveyed through Copyright Clearance Center, Inc.; 2000: article title screenshot from Mussi et al, 5 reused with permission from JNSPG; 2001: article title screenshot from Matsushima, Transcerebellomedullary fissure approach with special reference to methods of dissecting the fissure, J Neurosurg , vol 91, 2001, p. 257-264, by permission from JNSPG; 2021: article title screenshot from Matsushima et al, 12 by permission from Springer Nature. Images at 11:05 from Inoue T et al, "Surgical approach to the mesencephalic vascular malformation" [in Japanese], Surg Cereb Stroke , vol 26, 1998, p 288-289, by permission from the Japanese Society on Surgery for Cerebral Stroke. Cadaveric image at 11:56 from Matsushima T et al, "Exposure of the wide interior of the fourth ventricle without splitting the vermis: importance of cutting procedures for the tela choroidea" Neurosurg Rev , vol 35, 2012, p 563-571, used with permission from Springer Nature.

Trigeminal Schwannoma Surgery: Challenges in Preserving Facial Sensation

Treatments of schwannoma have dramatically improved in the previous few decades, but preservation of the functions of the originating nerve, such as facial sensation in trigeminal schwannomas, still remains challenging. As the preservation of facial sensation in trigeminal schwannomas has not been analyzed in detail, we here review our surgical experience of more than 50 trigeminal schwannoma patients, particularly focusing on their facial sensation. Since the facial sensation in each trigeminal division showed a different perioperative course even in a single patient, we investigated patient-based outcomes (average of the three divisions in each patient) and division-based outcomes separately. In the evaluation of patient-based outcomes, facial sensation remained postoperatively in 96% of all the patients, and improved in 26% and worsened in 42% of patients with preoperative hypesthesia. Posterior fossa tumors tended to most rarely disrupt facial sensation preoperatively, but were the most difficult to preserve facial sensation postoperatively. Facial pain was relieved in all six patients with preoperative neuralgia. In the division-based evaluation, facial sensation remained postoperatively in 83% of all the trigeminal divisions, and improved in 41% and worsened in 24% of the divisions with preoperative hypesthesia. The V3 region was most favorable before and after surgery, with the most frequent improvement and the least frequent functional loss. To clarify current treatment outcomes of the facial sensation and to achieve more effective preservation, standardized assessment methods of perioperative facial sensation may be required. We also introduce detailed MRI investigation methods for schwannoma, including contrast-enhanced heavily T2-weighted (CISS) imaging, arterial spin labeling (ASL), and susceptibility-weighted imaging (SWI), preoperative embolization for rare vascular-rich tumors, and modified techniques of the transpetrosal approach.

Intraoperative Continuous Neuromonitoring for Vestibular Schwannoma Surgery: Real-Time, Quantitative, and Functional Evaluation

In vestibular schwannoma surgery, neuromonitoring is essential to accomplish sufficient tumor resection while avoiding neurologic damage.^1-3 An ideal neuromonitoring method should include a real-time alert system, quantitative evaluation, and functional (not mechanical) assessment.⁴Video 1 demonstrates facial and hearing preservation surgery for vestibular schwannoma by the retrosigmoid transmeatal approach, under intraoperative continuous facial nerve monitoring and auditory brainstem response. Using a ball-type stimulating electrode placed on the proximal facial nerve, the evoked facial nerve electromyograms were continuously monitored by direct 1-Hz stimulation throughout the near-total tumor resection. The patient had no postoperative facial or hearing deterioration. The patient consented to the procedure before the surgery.