Original ArticleAwake Microvascular Decompression for Trigeminal Neuralgia: Concept and Initial Results
Introduction
The facial pain syndrome consistent with what we now know as trigeminal neuralgia (TN) was first described by Avicenna in 1037 AD.1 Some 700 hundred years later, Nicolas André coined the term “tic douloureux” in 1756 to describe the same pain syndrome, believing the intractable facial pain to be a consequence of compression of the facial sensory nerves.2 However, it was not until the early 20th century that Walter E. Dandy correlated the facial pain initially described by Avicenna and André to vascular compression of cranial nerve (CN) V.3
Dandy's discovery instigated numerous advances in the surgical management of TN, including the introduction of stereotactic radiosurgery (RS) by Lars Leksell in 19514 and of microvascular decompression (MVD) by Peter Jannetta in 1967.1 However, stereotactic RS did not truly become a feasible treatment option until the advent of the gamma knife in 1968. Since then, MVD has been established as the most efficacious treatment for TN.5
In this study, we assessed whether intraoperative pain evaluation under an awake anesthesia protocol (“awake MVD”) can identify and mitigate insufficient decompression of the trigeminal nerve, improving surgical outcomes. In addition, we evaluated whether awake MVD could expand the indications for this procedure in a subset of patients who are deemed too high risk for MVD based on their medical comorbidities and are referred for percutaneous procedures or RS.
Awake craniotomy is a well-established procedure that has been widely used for glioma resection and functional procedures that involve neurologic monitoring of eloquent cortical and subcortical areas.6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 Awake procedures also have been used for similar purposes in cerebrovascular surgery, specifically in carotid endarterectomy.25, 26, 27 Multiple case reports describing the use of awake craniotomy for aneurysms have also been presented in the literature, including 3 cases of distal vessel occlusion for mycotic aneurysm,28 ophthalmic artery aneurysm clipping with intraoperative visual testing,29 giant fusiform middle cerebral artery aneurysm trapping,30 and anterior choroidal artery aneurysm clipping.31 We recently published the first prospective series (n = 30) of awake clipping of unruptured intracranial aneurysms and compared our results with those of our own controls (retrospective series; n = 30) who underwent standard unruptured intracranial aneurysm clipping under general endotracheal anesthesia (GEA).32 The median length of stay was reduced from 5 days in our GEA control group to 3 days in our prospective awake craniotomy group. In addition, the rate of procedure-related stroke was reduced from 10% in the GEA control group to 3% in the prospective awake craniotomy group.32
We also recently published our experience in performing awake high-flow extracranial-to-intracranial bypass for complex aneurysms. We compared outcomes with those of our historical cohort who underwent the procedure under GEA. Absolute risk reduction in the awake craniotomy group (n = 30) relative to the historical control group (n = 110) was 7% for cerebrovascular accident, 9% for discharge to rehabilitation, and 10% for graft patency.33
Section snippets
Methods
We conducted a prospective study of 10 consecutive patients undergoing awake MVD for TN between August 2015 and August 2016. This report included all patients who underwent awake MVD for TN performed by the senior author (S.I.A.). During this interval, no patients underwent MVD with GEA. Pain outcomes were quantified using the Barrow Neurological Institute (BNI) Pain Intensity Scale34 (Table 1), with efficacious relief of pain defined as a score of I or II. Preoperatively, all patients were
Results
In this series, the median patient age was 65.5 years, with a female:male ratio of 6:4. All 10 patients tolerated the procedure well, and none required GEA intraoperatively or postoperatively. The study group included 3 patients who were initially being assessed for RS due to age and medical comorbidities. Nine patients had a successful surgical outcome (BNI Score I: n = 5, BNI Score II: n = 4). One patient did not experience pain relief (BNI Score IV); that patient also developed a
Discussion
In a recent meta-analysis investigating the safety and efficacy of MVD and RS for TN, Gubian and Rosahl reported initial success rates of 86.9% for MVD and 71.1% for RS.5 Based on these data and the literature, it is well established that MVD is the first-line treatment option for TN in younger patients and patients free of comorbidities. Comorbidities affecting the safety of GEA for MVD have historically excluded a subset of patients from undergoing this highly efficacious procedure,
Conclusions
Awake intraoperative testing for pain relief may be a powerful tool for identifying and mitigate incomplete decompression of CN V, potentially resulting in higher rates of successful MVD for TN. The subset of patients with TN who cannot tolerate GEA due to age or medical comorbidities may be candidates for awake MVD.
Acknowledgments
We thank Dr Wolf Stapelfeldt, Chair, Department of Anesthesiology, Saint Louis University, for his support of the pioneering concept of awake craniotomy for complex lesions.
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A Review of Medical and Surgical Options for the Treatment of Facial Pain
2022, Otolaryngologic Clinics of North AmericaCitation Excerpt :Studies continue to demonstrate strong pain relief in most patients. However, some 10% to 18% of patients may not achieve satisfactory pain relief following the operation.53,54 For those with continued pain after an MVD, further surgical exploration can be considered.
The Impact of Neuronavigation on the Surgical Outcome of Microvascular Decompression for Trigeminal Neuralgia
2021, World NeurosurgeryCitation Excerpt :The surgical procedure is widely described in the literature, and its clinical efficacy is well established.3-5 In the last few years, several authors have tried to improve the outcome and reduce the occurrence of complications by using the endoscopy during this kind of surgery.5,20-22 Nonetheless, because the overall morbidity of MVD remains non-negligible, technological advances should be implemented to improve the surgical outcome of these patients.
Treatment Outcomes in Trigeminal Neuralgia–A Systematic Review of Domains, Dimensions and Measures
2020, World Neurosurgery: XAwake microvascular decompression with fat-teflon sandwich technique: Clinical implications of a novel approach for cranial nerve neuralgias
2019, Journal of Clinical NeuroscienceCitation Excerpt :In 3/10 patients, intraoperative decision was altered based on failure of pain relief during the awake testing period. The one failure did not improve even with IN as well [9]. While in our series, of the 7 cases, one patient’s intra-op response guided us to re-explore and discover an additional vein as the main offending vessel despite an obvious arterial compression while in another case, the partial pain relief after MVD required an additional internal neurolysis for complete pain relief.
Perioperative approach in neurological surgery with the patient awake
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.