Vagus nerve stimulation complications

Vagus nerve stimulation complications

The most common side effects associated with Vagus nerve stimulation are hoarsenessthroat pain and coughingCardiac arrhythmia has been reported during lead tests performed during implantation of the device, but few cases during regular treatment.

After implanting vagus nerve electrodes to the cervical vagus nerve, side effects such as voice alterations and dyspnea or missing therapeutic effects are observed at different frequencies. Cervical vagus nerve branching might partly be responsible for these effects.

Adverse events (AEs) are generally associated with implantation or continuous on-off stimulation. Infection is the most serious implantation-associated AE. Bradycardia and asystole have also been described during implantation, as has vocal cord paresis, which can last up to 6 months and depends on surgical skill and experience. The most frequent stimulation-associated AEs include voice alteration, paresthesia, cough, headache, dyspnea, pharyngitis and pain, which may require a decrease in stimulation strength or intermittent or permanent device deactivation. Newer non-invasive VNS delivery systems do not require surgery and permit patient-administered stimulation on demand. These non-invasive VNS systems improve the safety and tolerability of VNS, making it more accessible and facilitating further investigations across a wider range of uses.

VNS battery replacement, revisions, and removals account for almost one-half of all VNS procedures. The findings suggest important long-term expectations for VNS including expected complications, battery life, and other surgical issues. Review of the literature suggests that the first large review of VNS revisions by a single center was done by Couch et al. The findings are important to better characterize long-term surgical expectations of VNS therapy. A significant portion of patients undergoing VNS therapy will eventually require revision 1).


In a retrospective study over an 8-year period, 13 patients underwent revision surgery due to lead failure. Lead failure was classified as either lead intrinsic damage or lead pin disengagement from the generator header. In the X-ray image, Zhou et al., defined an RC ratio that represented the portion of rear lead connector in the header receptacle. It was used to quantitatively evaluate the mechanical failure of the lead-header interface. Optimal procedures to identify and manage lead failure were established.

All 13 patients presented with high lead impedance ≥ 9 kOhms at the time of revision. Seven of ten patients with lead damage presented with increased seizure frequency after a period of seizure remission. In contrast to lead damages occurring relatively late (> 15 months), lead pin disengagement was usually found within the early months after device implantation. A significant association was found between an elevated RC ratio (≥ 35%) and lead pin disengagement. The microsurgical technique permitted the removal or replacement of the lead without adverse effects.

The method of measuring the RC ratio developed in this study is feasible for identifying lead disengagement at the generator level. Lead revision was an effective and safe procedure for patients experiencing lead failure 2).

Main risk of surgery is transient or permanent vocal cord paralysis.


Endotracheal Tube Electrode Neuromonitoring represents a safe adjunctive tool that can help localize the vagus nerve, particularly in the setting of varying anatomy or hazardous dissections. It may help reduce the potential for vagal trunk damage or electrode misplacement and potentially improve clinical outcomes 3).


1)

Couch JD, Gilman AM, Doyle WK. Long-term Expectations of Vagus Nerve Stimulation: A Look at Battery Replacement and Revision Surgery. Neurosurgery. 2016 Jan;78(1):42-6. doi: 10.1227/NEU.0000000000000985. PubMed PMID: 26678088.
2)

Zhou H, Liu Q, Zhao C, Ma J, Ye X, Xu J. Lead failure after vagus nerve stimulation implantation: X-ray examination and revision surgery. World Neurosurg. 2018 Dec 26. pii: S1878-8750(18)32893-6. doi: 10.1016/j.wneu.2018.12.070. [Epub ahead of print] PubMed PMID: 30593965.
3)

Katsevman GA, Josiah DT, LaNeve JE, Bhatia S. Endotracheal Tube Electrode Neuromonitoring for Placement of Vagal Nerve Stimulation for Epilepsy: Intraoperative Stimulation Thresholds. Neurodiagn J. 2022 Feb 28:1-12. doi: 10.1080/21646821.2022.2022911. Epub ahead of print. PMID: 35226831.

Woven EndoBridge (WEB)

Woven EndoBridge (WEB)

The Woven EndoBridge (WEB) (Sequent Medical, Aliso Viejo, California), is a ellipsoid braided-wire embolization device designed to provide flow disruption along the aneurysm neck 1).

Placed in the aneurysm, the device will modify the blood flow at the level of the neck and induce aneurysmal thrombosis. The WEB shape was designed to treat wide necked aneurysm. The device has been developed progressively from a dual-layer version (WEB DL) to single-layer versions (WEB SL and WEB SLS [single-layer spherical]).

This device does not require long-term antiplatelet use.

For the treatment of both ruptured and unruptured aneurysms. The WEB has received the CE mark and to date has been used to treat a wide variety of more than 1,400 aneurysms in Europe, Latin America and New Zealand. The WEB is not available for sale or use in the United States.

The WEB is a self-expanding, oblate, braided nitinol mesh.

The device is composed of an inner and outer braid held together by proximal, middle, and distal radiopaque markers, creating 2 compartments: 1 distal and 1 proximal. Depending on the device diame- ter, the inner and outer braids are 108 wires or 144 wires. Therefore, blood flow into a WEB-embolized aneurysm initially encounters 2 layers of wires comprising 216 or 288 wires, with the largest interwire distance ranging from 106 to 181 􏰅m, respectively, depending on the device size. The WEB implant is deployed—or retrieved before de- tachment—in a manner similar to that in endovascular coil systems, through microcatheters with an internal diameter 􏰆0.027 inch. For devices with a diameter of 􏰇7 mm, microcatheters with an internal diameter of 0.027 inch are used; and for devices with a diameter 􏰁7 mm, microcatheters with an internal diameter 0.032 inch are used. The detachment system is electrothermal and instantaneous. 2).


In a study, there was no difference in the early clinical course between those treated with WEB embolization, coil embolization, or neurosurgical clipping. Since WEB embolization is a valuable treatment alternative to coiling, it seems not justified to exclude this procedure from upcoming clinical SAH trials, yet the clinical long-term outcome, aneurysm occlusion, and retreatment rates have to be analyzed in further studies 3).

WEB Intrasaccular Therapy Study (WEB-IT)


The WEB Clinical Assessment of Intrasaccular Aneurysm Therapy (WEBCAST) trial is a prospective European trial evaluating the safety and efficacy of WEB in wide necked aneurysm of the bifurcation.

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It does not immediately secure the aneurysm in most subarachnoid hemorrhage cases. Second, it may not be suitable for embolization of wide-neck aneurysms with an unfavorable aspect ratio. To overcome these limitations, Zanaty et al., used the WEB device in conjunction with stenting and/or coiling.

They presented a technical note with an illustrated case-series, and provide a detailed step-by-step description on how the WEB device can be used in adjunct to coiling and/or stenting to achieve successful angiographic results. Accurate sizing of the WEB device before deployment is critical. Larger case-series are required to further assess the safety and success of these combined techniques 4).

Zhang et al. searched the PubMedOvid MEDLINE, and EMBASE databases between December 1, 2012 and June 30, 2018.

Studies that included five or more patients undergoing WEB for Wide necked intracranial aneurysms, reported an angiographic or clinical outcome and risk factors, and were published after December 1, 2012 were eligible.

Major outcomes included initial or short-term complete and adequate occlusion. Secondary outcomes included treatment failure, recanalizationmortalitymorbidity, and complication (e.g., thromboembolism or intraoperative rupture) rates. A random-effect model was used to pool the data. To assess risk factors for short-term angiographic outcomes and the most common complications, they conducted subgroup analyses and obtained odds ratios with 95% confidence intervals.

They included 36 studies (1759 patients with 1749 aneurysms). The initial complete and adequate occlusion rates were 35% and 77%, respectively. After a mean follow-up of 9.34 months, the short-term complete and adequate occlusion rates were 53% and 80%, respectively. Thromboembolism and recanalization were the most common complications (both 9%), followed by mortality (7%), morbidity (6%), failure (5%) and intraoperative rupture (3%). The following factors were related to higher short-term obliteration rates: unruptured status, in the anterior circulation, a medium neck (4-9.9 mm), newer-generation WEB and treatment without additional devices. Ruptured status, anterior circulation, preoperative antiplatelet therapy and newer-generation WEB were not significantly related to withto thromboembolism.

WEB has a satisfactory safety profile and shows promising efficacy in treating wide-neck intracranial aneurysms. They preliminarily identified several risk factors for short-term angiographic outcomes 5).

Woven EndoBridge case series.

A case of a shallow basilar tip aneurysm treated with the WEB device that required stabilization with Y-stent through radial access 6).


1)

Ding YH, Lewis DA, Kadirvel R, Dai D, Kallmes DF. The Woven EndoBridge: a new aneurysm occlusion device. AJNR Am J Neuroradiol. 2011 Mar;32(3):607-11. doi: 10.3174/ajnr.A2399. Epub 2011 Feb 17. PubMed PMID: 21330397.
2)

Pierot L, Liebig T, Sychra V, Kadziolka K, Dorn F, Strasilla C, Kabbasch C, Klisch J. Intrasaccular flow-disruption treatment of intracranial aneurysms: preliminary results of a multicenter clinical study. AJNR Am J Neuroradiol. 2012 Aug;33(7):1232-8. doi: 10.3174/ajnr.A3191. Epub 2012 Jun 7. PubMed PMID: 22678844.
3)

Sauvigny T, Nawka MT, Schweingruber N, Mader MM, Regelsberger J, Schmidt NO, Westphal M, Czorlich P. Early clinical course after aneurysmal subarachnoid hemorrhage: comparison of patients treated with Woven EndoBridge, microsurgical clipping, or endovascular coiling. Acta Neurochir (Wien). 2019 Jul 6. doi: 10.1007/s00701-019-03992-4. [Epub ahead of print] PubMed PMID: 31280480.
4)

Zanaty M, Roa JA, Dandapat S, Samaniego EA, Jabbour P, Hasan D. Diverse Use of the WEB Device: A Technical Note on WEB Stenting and WEB Coiling of Complex Aneurysms. World Neurosurg. 2019 Jul 10. pii: S1878-8750(19)31933-3. doi: 10.1016/j.wneu.2019.07.027. [Epub ahead of print] PubMed PMID: 31301439.
5)

Zhang SM, Liu LX, Ren PW, Xie XD, Miao J. Effectiveness, safety and risk factors of Woven EndoBridge device in the treatment of wide-neck intracranial aneurysms : systematic review and meta-analysis. World Neurosurg. 2019 Aug 13. pii: S1878-8750(19)32175-8. doi: 10.1016/j.wneu.2019.08.023. [Epub ahead of print] PubMed PMID: 31419591.
6)

Nordmann NJ, Weber MW, Dayoub H. Woven Endobridge (WEB) augmented by Y-stent in a shallow basilar tip aneurysm. J Cerebrovasc Endovasc Neurosurg. 2022 Feb 17. doi: 10.7461/jcen.2022.E2021.08.006. Epub ahead of print. PMID: 35172073.

Robotic pedicle screw placement

Robotic pedicle screw placement

Robotic spinal fixation is associated with increased screw placement accuracy and similar operative blood loss, length of stay, and operative duration. These findings support the safety and cost-effectiveness of robotic spinal surgery across the spectrum of robotic systems and screw types 1).


In addition to demonstrating excellent pedicle screw accuracy, early studies have explored the impact of robot-assisted spine surgery on reducing radiation time, length of hospital stay, operative time, and perioperative complications in comparison to conventional freehand technique. The Mazor X Stealth Edition was introduced in 2018. This robotic system integrates Medtronic’s Stealth navigation technology into the Mazor X platform, which was introduced in 2016. It is unclear what the impact of these advancements have made on clinical outcomes.


In a multicenter study, both robot systems achieved excellent screw accuracy and low robot time per screw. However, using Stealth led to significantly less fluoroscopic radiation time, lower robot abandonment rates, and reduced blood transfusion rates than Mazor X. Other factors including length of stay, and 90-day complications were similar 2)

Ha Y. Robot-Assisted Spine Surgery: A Solution for Aging Spine Surgeons. Neurospine. 2018 Sep;15(3):187-188. doi: 10.14245/ns.18edi.003. Epub 2018 Sep 11. PubMed PMID: 30196675.


In three cadavers 12 pedicle screws were implanted in thoraco-lumbar segments with the robotic surgery assistant. 3D-fluoroscopy was performed for preoperative referencing, planning and identification of postoperative screw position. The radiation exposure of fluoroscopy and a CT scanner was compared, measuring the Computed Tomography Dose Index (CTDIw ).

Pedicle screw positioning was graded according to the Gertzbein-Robbins classification: Eleven of 12 pedicle screws showed optimal transpedicular position (Grade 1), one was positioned less than 2 mm outside (Grade 2). No major deviations were observed. Referencing with 3D-fluoroscopy resulted in a CTDIw reduction of 84% in the cervical- and 33% in the lumbar spine.

Robot-guided PS placement, using 3D-fluoroscopy for referencing, is a reliable tool for minimally invasive PS implantation; radiation exposure can be reduced 3).


Menger et al., investigated the cost effectiveness of adding robotic technology in spine surgery to an active neurosurgical practice.

The time of operative procedures, infection rates, revision rates, length of stay, and possible conversion of open to minimally invasive spine surgery (MIS) secondary to robotic image guidance technology were calculated using a combination of institution-specific and national data points. This cost matrix was subsequently applied to 1 year of elective clinical case volume at an academic practice with regard to payor mix, procedural mix, and procedural revenue.

A total of 1,985 elective cases were analyzed over a 1-year period; of these, 557 thoracolumbar cases (28%) were analyzed. Fifty-eight (10.4%) were MIS fusions. Independent review determined an additional ~10% cases (50) to be candidates for MIS fusion. Furthermore, 41.4% patients had governmental insurance, while 58.6% had commercial insurance. The weighted average diagnosis-related group reimbursement for thoracolumbar procedures for the hospital system was calculated to be $25,057 for Medicare and $42,096 for commercial insurance. Time savings averaged 3.4 minutes per 1-level MIS procedure with robotic technology, resulting in annual savings of $5,713. Improved pedicle screw accuracy secondary to robotic technology would have resulted in 9.47 revisions being avoided, with cost savings of $314,661. Under appropriate payor mix components, robotic technology would have converted 31 Medicare and 18 commercial patients from open to MIS. This would have resulted in 140 fewer total hospital admission days ($251,860) and avoided 2.3 infections ($36,312). Robotic surgery resulted in immediate conservative savings estimate of $608,546 during a 1-year period at an academic center performing 557 elective thoracolumbar instrumentation cases.

Application of robotic spine surgery is cost-effective, resulting in lesser revision surgery, lower infection rates, reduced length of stay, and shorter operative time. Further research is warranted, evaluating the financial impact of robotic spine surgery 4).


Several randomized controlled trials (RCTs) and cohort studies involving robotic-assisted (RA) and free-hand with fluoroscopy-guided (FH) and published before January 2017 were searched for using the Cochrane LibraryOvidWeb of SciencePubMed, and EMBASE databases. A total of 55 papers were selected. After the full-text assessment, 45 clinical trials were excluded. The final meta-analysis included 10 articles.

The accuracy of pedicle screw placement within the RA group was significantly greater than the accuracy within the FH group (odds ratio 95%, “perfect accuracy” confidence interval: 1.38-2.07, P < .01; odds ratio 95% “clinically acceptable” Confidence Interval: 1.17-2.08, P < .01).

There are significant differences in accuracy between RA surgery and FH surgery. It was demonstrated that the RA technique is superior to the conventional method in terms of the accuracy of pedicle screw placement 5).


In 2013 a study evaluated the outcomes of robotic-assisted screw placement in a consecutive series of 102 patients.

Data were recorded from technical notes and operative records created immediately following each surgery case, in which the robotic system was used to guide pedicle screw placement. All cases were performed at the same hospital by a single surgeon. The majority of patients had spinal deformity and/or previous spine surgery. Each planned screw placement was classified as: (1) successful/accurately placed screw using robotic guidance; (2) screw malpositioned using robot; (3) use of robot aborted and screw placed manually; (4) planned screw not placed as screw deemed non essential for construct stability. Data from each case were reviewed by two independent researchers to indentify the diagnosis, number of attempted robotic guided screw placements and the outcome of the attempted placement as well as complications or reasons for non-placement.

Robotic-guided screw placement was successfully used in 95 out of 102 patients. In those 95 patients, 949 screws (87.5 % of 1,085 planned screws) were successfully implanted. Eleven screws (1.0 %) placed using the robotic system were misplaced (all presumably due to “skiving” of the drill bit or trocar off the side of the facet). Robotic guidance was aborted and 110 screws (10.1 %) were manually placed, generally due to poor registration and/or technical trajectory issues. Fifteen screws (1.4 %) were not placed after intraoperative determination that the screw was not essential for construct stability. The robot was not used as planned in seven patients, one due to severe deformity, one due to very high body mass index, one due to extremely poor bone quality, one due to registration difficulty caused by previously placed loosened hardware, one due to difficulty with platform mounting and two due to device technical issues.

Of the 960 screws that were implanted using the robot, 949 (98.9 %) were successfully and accurately implanted and 11 (1.1 %) were malpositioned, despite the fact that the majority of patients had significant spinal deformities and/or previous spine surgeries. “Tool skiving” was thought to be the inciting issue with the misplaced screws. Intraoperative anteroposterior and oblique fluoroscopic imaging for registration is critical and was the limiting issue in four of the seven aborted cases 6).

Robotic pedicle screw placement learning curve.


1)

Himstead AS, Shahrestani S, Brown NJ, Produturi G, Shlobin NA, Al Jammal O, Choi EH, Ransom SC, Daniel Diaz-Aguilar L, Sahyouni R, Abraham M, Pham MH. Bony fixation in the era of spinal robotics: A systematic review and meta-analysis. J Clin Neurosci. 2022 Jan 19;97:62-74. doi: 10.1016/j.jocn.2022.01.005. Epub ahead of print. PMID: 35065405.
2)

Lee NJ, Zuckerman SL, Buchanan IA, Boddapati V, Mathew J, Leung E, Park PJ, Pham MH, Buchholz AL, Khan A, Pollina J, Mullin JP, Jazini E, Haines C, Schuler TC, Good CR, Lombardi JM, Lehman RA. Is There a Difference Between Navigated and Non-Navigated Robot Cohorts in Robot-Assisted Spine Surgery? A Multicenter, Propensity-Matched Analysis of 2,800 Screws and 372 Patients. Spine J. 2021 May 19:S1529-9430(21)00253-9. doi: 10.1016/j.spinee.2021.05.015. Epub ahead of print. PMID: 34022461.
3)

Spyrantis A, Cattani A, Seifert V, Freiman TM, Setzer M. Minimally invasive percutaneous robotic thoracolumbar pedicle screw implantation combined with three-dimensional-fluoroscopy can reduce radiation: a cadaver and phantom study. Int J Med Robot. 2019 Jun 19:e2022. doi: 10.1002/rcs.2022. [Epub ahead of print] PubMed PMID: 31216120.
4)

Menger RP, Savardekar AR, Farokhi F, Sin A. A Cost-Effectiveness Analysis of the Integration of Robotic Spine Technology in Spine Surgery. Neurospine. 2018 Aug 29. doi: 10.14245/ns.1836082.041. [Epub ahead of print] PubMed PMID: 30157583.
5)

Fan Y, Du JP, Liu JJ, Zhang JN, Qiao HH, Liu SC, Hao DJ. Accuracy of pedicle screw placement comparing robot-assisted technology and the free-hand with fluoroscopy-guided method in spine surgery: An updated meta-analysis. Medicine (Baltimore). 2018 Jun;97(22):e10970. doi: 10.1097/MD.0000000000010970. Review. PubMed PMID: 29851848; PubMed Central PMCID: PMC6392558.
6)

Hu X, Ohnmeiss DD, Lieberman IH. Robotic-assisted pedicle screw placement: lessons learned from the first 102 patients. Eur Spine J. 2013 Mar;22(3):661-6. doi: 10.1007/s00586-012-2499-1. Epub 2012 Sep 14. PubMed PMID: 22975723; PubMed Central PMCID: PMC3585630.
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