Category: Pain

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Gamma Knife Radiosurgery for Multiple Sclerosis-Associated Trigeminal Neuralgia

 

Neurosurgery 85:E933–E939, 2019

Trigeminal neuralgia in the setting of multiple sclerosis (MS-TN) is a challenging condition to manage that is commonly treated with Gamma Knife radiosurgery (GKRS; Elekta AB). However, data regarding the efficacy of this treatment are somewhat limited, particularly for repeat GKRS.

OBJECTIVE: To report outcomes of GKRS for MS-TN from a cohort study.

METHODS: Retrospective review of our GKRS database identified 77 cases of unilateral MS-TN (UMSTN) in 74 patients treated with GKRS between 2001 and 2016, with 37 cases undergoing repeat GKRS. Background medical history, treatment outcomes and complications, and dosimetric data were obtained by retrospective chart reviews and telephone interviews.

RESULTS:Eighty two percent of UMSTN cases achieved Barrow Neurological Institute (BNI) IIIb or better pain relief following initial GKRS for a median duration of 1.1 yr. Estimated rates ofpainreliefat1,3,and5yr were 51,39,and29% respectively.Eighty-eightpercentachieved BNI IIIb or better pain relief after repeat GKRS for a median duration of 4.0 yr. Estimated rates of pain relief at 1 and 3 yr were 70 and 54%, respectively. Median doses for initial and repeat GKRS were 85 and 80 Gy to the 100% isodose line, respectively. Those with MS-TN had a shorter duration of BNI IIIb or better pain relief after initial (4.6 vs 1.1 yr), but not repeat GKRS (3.8 vs 4.0 yr) compared to a historical cohort from our institution.

CONCLUSION: GKRS is an effective, well-tolerated treatment for patientswith MS-TN. More durable relief is often achieved with repeat GKRS.

 

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The Effectiveness of Percutaneous Balloon Compression, Thermocoagulation, and Glycerol Rhizolysis for Trigeminal Neuralgia in Multiple Sclerosis

Neurosurgery 85:E684–E692, 2019

Balloon compression (BC),thermocoagulation (TC),and glycerol rhizolysis (GR) are percutaneous surgical options for trigeminal neuralgia (TN). Whether the outcomes of these procedures in multiple sclerosis-related TN (MS-TN) are as effective as in idiopathic TN (ITN) is unknown.

OBJECTIVE: To retrospectively compare pain relief, complications, and durability achieved by these 3 types of procedures in MS-TN and ITN.

METHODS: Two hundred and four patients with typical TN were treated percutaneously: 33 had MS-TN (64 procedures) and 171 had ITN (329 procedures). All were performed by 1 of 2 neurosurgeons; interviews enabled long-term data to be gathered by an independent observer.

RESULTS: MS-TN patients (53.1%) had Barrow Neurological Institute pain scores of I or II after a percutaneous procedure, compared with 59.3% in the ITN cohort; there was no difference in initial relief between the 2 groups overall (P = .52). There was a trend toward fewer complications in MS-TN compared with ITN (23.4% vs 33.7%, respectively; P = .058). Kaplan–Meier analysis demonstrated no difference in durability of relief in MS-TN (median 23.0 mo) compared with ITN overall (median 24.0 mo; P = .75). Subgroup analysis demonstrated longer relief from BC and TC compared with GR in MS-TN (P = .013). Multivariate analysis confirmed that although the presence of MS does not predict durability of outcome, postoperative numbness (P = .0046) and undergoing a repeat procedure (P = .037) were significant predictors.

CONCLUSION: BC and TC are safe and effective in MS-TN. Postoperative numbness is the strongest prognostic factor in MS-TN.

 

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The Spectrum of Trigeminal Neuralgia Without Neurovascular Compression

Neurosurgery 85:E553–E559, 2019

In trigeminal neuralgia type 1 (TN1), neurovascular compression (NVC) is often assumed to be the pain initiating mechanism. NVC can be surgically addressed by microvascular decompression (MVD). However, some patients with TN1 present without NVC (WONVC).

OBJECTIVE: To characterize and analyze the clinical spectrum of a TN1 patient population WONVC.

METHODS: A retrospective chart review of patients presenting with TN1 between 2007 and 2017 was performed. Patients who were potential candidates for MVD surgery underwent high-resolution imaging with 3-dimensional (3D) reconstruction to address the presence, or absence, of NVC. Demographic data about the populations with NVC (WNVC) and WONVC were collected.

RESULTS: Of 242 patients with TN1, 32% did not have NVC. Patients WONVC were on average 10.6 yr younger than those WNVC.TN1onset in patients WONVC was more frequent below 48.7 yr, and the opposite was found in patients WNVC. Compared to patients WNVC, those WONVC were predominantly female (odds ratio 4.8), on average were 4 yr younger at symptom onset (34.7 yr) and 7.8 yr younger at first clinic visit, and had a 3.7 yr shorter symptom duration.

CONCLUSION: Patients presenting with TN1 WONVC were predominantly females in their mid-30s with short symptom duration. In the absence of NVC, this subgroup of TN1 patients has limited surgical options, and potentially a longer condition duration that must be managed medically or surgically. This population WONVC might provide insights into the true pathophysiology of TN1.

 

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Early postsurgical diffusivity metrics for prognostication of long-term pain relief after Gamma Knife radiosurgery for trigeminal neuralgia

J Neurosurg 131:539–548, 2019

Gamma Knife radiosurgery (GKRS) is an important treatment modality for trigeminal neuralgia (TN). Current longitudinal assessment after GKRS relies primarily on clinical diagnostic measures, which are highly limited in the prediction of long-term clinical benefit. An objective, noninvasive, predictive tool would be of great utility to advance the clinical management of patients. Using diffusion tensor imaging (DTI), the authors’ aim was to determine whether early (6 months post-GKRS) target diffusivity metrics can be used to prognosticate long-term pain relief in patients with TN.

METHODS Thirty-seven patients with TN treated with GKRS underwent 3T MRI scans at 6 months posttreatment. Diffusivity metrics of fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity were extracted bilaterally from the radiosurgical target of the affected trigeminal nerve and its contralateral, unaffected nerve. Early (6 months post-GKRS) diffusivity metrics were compared with long-term clinical outcome. Patients were identified as long-term responders if they achieved at least 75% reduction in preoperative pain for 12 months or longer following GKRS.

RESULTS Trigeminal nerve diffusivity at 6 months post-GKRS was predictive of long-term clinical effectiveness, where long-term responders (n = 19) showed significantly lower fractional anisotropy at the radiosurgical target of their affected nerve compared to their contralateral, unaffected nerve and to nonresponders. Radial diffusivity and mean diffusivity, correlates of myelin alterations and inflammation, were also significantly higher in the affected nerve of long-term responders compared to their unaffected nerve. Nonresponders (n = 18) did not exhibit any characteristic diffusivity changes after GKRS.

CONCLUSIONS The authors demonstrate that early postsurgical target diffusivity metrics have a translational, clinical value and permit prediction of long-term pain relief in patients with TN treated with GKRS. Importantly, an association was found between the footprint of radiation and clinical effectiveness, where a sufficient level of microstructural change at the radiosurgical target is necessary for long-lasting pain relief. DTI can provide prognostic information that supplements clinical measures, and thus may better guide the postoperative assessment and clinical decision-making for patients with TN.

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Dorsal anterior cingulate cortex (ACC) deep brain stimulation (DBS): a promising surgical option for the treatment of refractory thalamic pain syndrome (TPS)

Acta Neurochirurgica (2019) 161:1579–1588

Neuroimaging evidences and previous successful case series of cingulotomy for cancer pain have disclosed the key- role of the dorsal anterior cingulate cortex (ACC) in the generation of the empathic and affective dimension of pain. The aim of this study is to assess the effectiveness and safety of ACC neuromodulation for the treatment of the thalamic pain syndrome (TPS), a chronic neuropathic disease often complicated by severe affective and emotional distress in the long term.

Method From January 2015 to April 2017, 5 patients with pure drug-refractory TPS underwent ACC deep brain stimulation (DBS) at our institution. Quantitative assessment of pain and health-related quality of life were performed 1 day before surgery and postoperatively at 6 and 18 months by using the numeric rating scale (NRS), the 36-item short-form health survey (SF-36), and the McGill pain and the EuroQol5-domain questionnaires.

Results Mean age at surgery was 56.2 years (range, 47–66). NRS score improved by 37.9% at 6 months (range, − 22.2 to − 80%) and by 35% at 18 months (range, − 11.1 to − 80%). At the last follow-up, one patient reported a relevant pain reduction (NRS 2), only complaining of mild pain poorly interfering with activities of daily living. Concomitant improvements in the McGill and EuroQol5-domain pain questionnaires, SF-36 total and sub-item scores were also noticed at each follow-up. No surgical or stimulation-related complications occurred during the study period.

Conclusions ACC DBS may be a safe and promising surgical option to alleviate discomfort and improve the overall quality of life in a patient affected by drug-resistant TPS. Further prospective, larger, and randomized studies are needed to validate these findings.

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Arachnoiditis as an outcome factor for microvascular decompression in classical trigeminal neuralgia

Acta Neurochirurgica (2019) 161:1589–1598

Neurovascular conflict is considered a key element of classical trigeminal neuralgia (TN) and consequently, mi- crovascular decompression (MVD) is an effective treatment. Nevertheless, failures of MVD are described by many authors. In some patients, the arachnoid membranes surrounding the trigeminal nerve and neighbouring vessels may be thickened and adhesive. Here we analyse the impact of such focal arachnoiditis on outcome after MVD for TN.

Methods A cohort of prospectively followed patients after their MVD was reviewed for intraoperative, imaging and clinical data if findings of arachnoiditis during MVD were described. Long-term outcome assessment was the main endpoint.

Results We reviewed data from 395 MVD procedures, performed for TN from 2001 to 2014. Intraoperative evidence of focal arachnoiditis, as described by the surgeon, has been noted in 51 patients (13%). In 35 (68.6%), neuralgia was typical and in the other 17 (31.4%) it was atypical.
As expected by definition, neurovascular conflict was found in 49 interventions (96%); it was predominantly arterial in 27 (52.9%). Accompanying arachnoiditis was encountered: mild in 20 interventions (39.2%), severe in 31 (60.8%).
A successful result (BNI I or II) was achieved in 29 patients (56.9%). The other 22 patients (43.1%) had persistence or recurrence of pain. Overall KM probability of being pain free at 15 years was 72%.

Conclusions Intraoperative finding of arachnoiditis during MVD for classical trigeminal neuralgia is associated with poorer outcome than that of classical trigeminal neuralgia in general. This is particularly true for low grades of conflict.

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Pain-free and pain-controlled survival after sectioning the nervus intermedius in nervus intermedius neuralgia: a single-institution review

J Neurosurg 131:352–359, 2019

Nervus intermedius neuralgia (NIN) or geniculate neuralgia is a rare facial pain condition consisting of sharp, lancinating pain deep in the ear and can occur alongside trigeminal neuralgia (TN). Studies on the clinical presentation, intraoperative findings, and ultimately postoperative outcomes are extremely limited. The aim of this study was to examine the clinical presentation and surgical findings, and determine pain-free survival after sectioning of the nervus intermedius (NI).

METHODS The authors conducted a retrospective chart review and survey of patients who were diagnosed with NIN at one institution and who underwent neurosurgical interventions. Pain-free survival was determined through chart review and phone interviews using a modified facial pain and quality of life questionnaire and represented as Kaplan-Meier curves.

RESULTS The authors found 15 patients with NIN who underwent microsurgical intervention performed by two sur- geons from 2002 to 2016 at a single institution. Fourteen of these patients underwent sectioning of the NI, and 8 of 14 had concomitant TN. Five patients had visible neurovascular compression (NVC) of the NI by the anterior inferior cerebellar artery in most cases where NVC was found. The most common postoperative complaints were dizziness and vertigo, diplopia, ear fullness, tinnitus, and temporary facial nerve palsy. Thirteen of the 14 patients reportedly experienced pain relief immediately after surgery. The mean length of follow-up was 6.41 years (range 8 months to 14.5 years). Overall recurrence of any pain was 42% (6 of 14), and 4 patients (isolated NIN that received NI sectioning alone) reported their pain was the same or worse than before surgery at longest follow-up. The median pain-free survival was 4.82 years ± 14.85 months. The median pain-controlled survival was 6.22 years ± 15.78 months.

CONCLUSIONS In this retrospective review, sectioning of the NI produced no major complications, such as permanent facial weakness or deafness, and was effective for patients when performed in addition to other procedures. After sectioning of the NI, patients experienced 4.8 years pain free and experienced 6.2 years of less pain than before surgery. Alone, sectioning of the NI was not effective. The pathophysiology of NIN is not entirely understood. It appears that neurovascular compression plays only a minor role in the syndrome and there is a high degree of overlap with TN.

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Nervus intermedius and the surgical management of geniculate neuralgia

J Neurosurg 131:343–351, 2019

Geniculate neuralgia (GN) is an uncommon craniofacial pain syndrome attributable to nervus intermedius (NI) dysfunction. Diagnosis and treatment can be challenging, due to the complex nature of ear sensory innervation, resulting in clinical overlap with trigeminal neuralgia (TN) and glossopharyngeal neuralgia (GPN).

METHODS A retrospective review of a prospective neurosurgical database at our institution was performed, 2000–2017, with a corresponding systematic literature review. Pain outcomes were dichotomized as unfavorable for unchanged/worsened symptoms versus favorable if improved/resolved. Eight formalin-fixed brains were examined to describe NI at the brainstem.

RESULTS Eleven patients were surgically treated for GN—9 primary, 2 reoperations. The median age was 48, 7 pa- tients were female, and the median follow-up was 11 months (range 3–143). Seven had ≥ 2 probable cranial neuralgias. NI was sectioned in 9 and treated via microvascular decompression (MVD) in 2. Five patients underwent simultaneous treatment for TN (4 MVD; 1 rhizotomy) and 5 for GPN (3 MVD; 2 rhizotomy). Eleven reported symptomatic improvement (100%); 8 initially reported complete resolution (73%). Pain outcomes at last contact were favorable in 8 (73%)—all among the 9 primary operations (89% vs 0%, p = 0.054). Six prior series reported outcomes in 111 patients.

CONCLUSIONS GN is rare, and diagnosis is confounded by symptomatic overlap with TN/GPN. Directed treatment of all possible neuralgias improved pain control in almost all primary operations. Repeat surgery seems a risk factor for an unfavorable outcome. NI is adherent to superomedial VIII at the brainstem; the intermediate/cisternal portion is optimal for visualization and sectioning.

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Microsurgical rhizotomy for trigeminal neuralgia in MS patients

J Neurosurg 130:1877–1888, 2019

Patients with multiple sclerosis (MS)–associated trigeminal neuralgia (TN) have higher recurrence and retreatment rates than non-MS patients. The optimal management strategy and role for microsurgical rhizotomy (MSR) for MS-TN remains to be determined. The aim of this study was to report time to treatment failure (TTF) and pain scores following MSR compared to percutaneous and Gamma Knife procedures.

METHODS Time to treatment failure was analyzed after MSR (n = 14) versus prior procedures (n = 53) among MS-TN patients. Kaplan-Meier curves and log-rank test were utilized to compare TTF after MSR versus prior procedures using the same cohort of patients as their own control group. Subsequent analysis compared TTF after MSR to TTF after 93 other procedures among a second cohort of 18 MS-TN patients not undergoing MSR. BNI pain scores were compared between MSR and other procedures among the MS-TN cohort using a chi-square test.

RESULTS TTF was significantly longer after MSR than after other procedures in the MSR cohort (median TTF 79 vs 10 months, respectively, p < 0.0001). Similarly, TTF was longer after MSR than after prior procedures in the non-MSR cohort (median TTF 79 vs 13 months, respectively, p < 0.001). MSR resulted in a higher proportion of excellent pain scores when compared to other procedures in the non-MSR cohort (77% vs 29%, p < 0.001). Probability of treatment survival was higher after MSR than after other procedures at all time points (3, 6, 12, 24, 36, and 48 months). There were no deaths or major complications after MSR.

CONCLUSIONS TTF was significantly longer following MSR compared to prior procedures in MS-TN patients. Additionally, a higher proportion of patients achieved excellent BNI pain scores after MSR.

 

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Hemodynamic features of offending vessels at neurovascular contact in patients with trigeminal neuralgia and hemifacial spasm

J Neurosurg 130:1870–1876, 2019

Offending vessels at the site of neurovascular contact (NVC) in patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS) may have specific hemodynamic features. The purpose of this study was to investigate the wall shear stress (WSS) of offending vessels at NVCs by conducting a computational fluid dynamics (CFD) analysis.

METHODS The authors retrospectively analyzed the cases of 20 patients (10 with TN and 10 with HFS) evaluated by 3D CT angiography and used the imaging findings for analysis of the hemodynamic parameters. The 3D CFD images were directly compared with the NVCs determined by simulated multifusion images of CT angiogram and MR cisternogram, and operative photos. The magnitudes of the WSS (WSSm) at the proximal (WSSm-p), just-beginning (WSSm-j), contact site (WSSm-s), and distal (WSSm-d) areas of each NVC were analyzed. The ratios of the WSSm-j, WSSm-s, and WSSm-d areas to the WSSm-p area were calculated individually. The direction of the WSS (WSSv) and its temporal variation (WSSvV) were depicted and morphologically compared with the NVC confirmed by simulated images and operative findings.

RESULTS The ratios of WSSm at the just-beginning and the contact site to the proximal area of the NVCs (WSSm-j/ WSSm-p and WSSm-s/WSSm-p) were both significantly higher than that at the distal area (WSSm-d/WSSm-p) (p < 0.05). The WSSv and WSSvV at the NVCs showed small variation in a single cardiac cycle, especially along the areas that were in contact with the affected nerve.

CONCLUSIONS Areas of relatively high WSSm and temporal variation of WSSm (WSSmV) were observed at the NVCs. Less mobility of the WSSv and WSSvV was detected along the side of the vessels in contact with the nerves. These findings may be consistent with the actual area of the NVC. Hemodynamic features of the site of NVC can be added to the preoperative simulation for MVD surgery, which may be useful for the diagnosis and treatment planning of TN and HFS.

 

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Comparing Microvascular Decompression with Gamma Knife Radiosurgery for Trigeminal Neuralgia. A Cost-Effectiveness Analysis

World Neurosurg. (2019) 125:207-216

Both microvascular decompression (MVD) and Gamma Knife radiosurgery (GKRS) are time-tested treatment modalities for trigeminal neuralgia (TN). There is little evidence in the literature studying these modalities head to head in a cost-effectiveness comparison.

OBJECTIVE: To evaluate the cost-effectiveness of MVD compared with GKRS for treating patients with TN.

METHODS: We developed a Markov cost-effectiveness model for the U.S. health care system to account for all costs related to MVD and GKRS as treatment modalities for TN, from the health care system perspective, over a patient lifetime horizon. A base case was estimated using data from previous studies, from our own GKRS experience, and from a current data analysis of patients undergoing MVD. We derived model inputs, including health care costs, survival, and utility estimates, from the literature. We used age-specific, sex-specific, and race-specific mortality from national registries. Costs studied included those for MVD, for GKRS, for treating complications from either procedure, and for medications throughout patient lifetimes. We performed multiple 1-way, 2-way, and probabilistic sensitivity analyses to confirm the robustness of model assumptions and results. The incremental cost-effectiveness ratio (ICER), with a threshold of $50,000 per quality-adjusted lifeyear (QALY) gained, defined cost-effectiveness.

RESULTS: The base case had an ICER of $12,154 per QALY for MVD compared with GKRS. Probabilistic sensitivity (Monte Carlo) analysis showed that MVD was cost-effective in 70% of model iterations. GKRS was favored when the willingness to pay threshold was <$12,000 per QALY gained.

CONCLUSIONS: In patients medically eligible for either procedure, we found MVD to be the most cost-effective modality to treat TN, primarily because of its reported greater durability. MVD remained the most cost-effective strategy across a broad range of model input values in sensitivity analyses

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Vidian Neurectomy for Management of Chronic Cluster Headache

Neurosurgery (84),1059–1064, 2019

Management of chronic cluster headache (CCH) remains a challenging endeavor, and the optimal surgical approach for medically refractory CCH remains controversial.

OBJECTIVE: To conduct a preliminary evaluation of the efficacy and safety of vidian neurectomy (VN) in patients with medically refractory CCH.

METHODS: Between March 2013 and December 2015, 9 CCH patients, all of whom had failed to respond to conservative therapy, underwent VN with a precise nerve cut and maximal preservation of the sphenopalatine ganglion. Data included demographic variables, cluster headache onset and duration, mean attack frequency, mean attack intensity, and pain disability index measures pre- and through 12-mo postsurgery.

RESULTS: Seven of the 9 cases (77.8%) showed immediate improvement. Improvement was delayed by 1 mo in 1 patient, after which the surgical effects of pain relief were maintained throughout the follow-up period. One patient (11.1%) did not improve after surgery. One year after VN, patients’ mean attack frequency, mean attack intensity, and pain disability index decreased by 54.5%, 52.9%, and 56.4%, respectively. No patient experienced treatment-related side effects or complications.

CONCLUSION: VN is an effective treatment method for CCH patients. Precise Vidian nerve identification and maximal preservation of the sphenopalatine ganglion may achieve good surgical outcomes and dramatically improve quality of life among patients, without significant adverse events.

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Long-Term Outcome of Spinal Cord Stimulation in Failed Back Surgery Syndrome: 20 Years of ExperienceWith 224 Consecutive Patients

Neurosurgery (84) 5-1011–1018

Failed back surgery syndrome (FBSS) is a challenging condition that lacks a curative treatment. In selected patients, spinal cord stimulation (SCS) has provided a satisfactory outcome.

OBJECTIVE: To evaluate the long-term outcome of SCS in FBSS, as measured by (1) the explantation rate, (2) complications, and (3) patient satisfaction with the global perceived effect (GPE).

METHODS: We studied 224 consecutive FBSS patients who underwent an SCS trial with surgically implanted leads at our hospital between January 1996 and December 2014. The patients’ satisfaction with the GPE of treatment was measured through a postal questionnaire at the end of follow-up.

RESULTS: Based on a 1-wk trial, permanent SCS was implanted in 175 (78%) patients. Out of these patients, 153 (87%) reported satisfactory outcomes after 2 mo. During the mean follow-up of 6 yr, 34 (19%) of SCS devices were permanently explanted due to inadequate pain relief, and 11 (6%) were explanted for other reasons. Electrode revision due to inadequate pain relief was done for 22 patients. In total, 26 complications were reported due to: 7 deep infections, 11 hardwaremalfunctions, 1 subcutaneous hematoma, 4 instances of discomfort due to the pulse generator, and 3 electrode migrations. One hundred thirty patients (74%) continued with SCS until the end of follow-up. Of them, 61 (47%) returned the questionnaire, and 42 (69%) reported substantially improved or better GPE.

CONCLUSION: SCS can provide a good outcome in the treatment of FBSS. Patient selection could be further improved by developing novel predictive biomarkers.

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Contemporary concepts of pain surgery

J Neurosurg 130:1039–1049, 2019

Pain surgery is one of the historic foundations of neurological surgery. The authors present a review of contemporary concepts in surgical pain management, with reference to past successes and failures, what has been learned as a subspecialty over the past 50 years, as well as a vision for current and future practice.

This subspecialty confronts problems of cancer pain, nociceptive pain, and neuropathic pain. For noncancer pain, ablative procedures such as dorsal root entry zone lesions and rhizolysis for trigeminal neuralgia (TN) should continue to be practiced. Other procedures, such as medial thalamotomy, have not been proven effective and require continued study. Dorsal rhizotomy, dorsal root ganglionectomy, and neurotomy should probably be abandoned.

For cancer pain, cordotomy is an important and underutilized method for pain control. Intrathecal opiate administration via an implantable system remains an important option for cancer pain management.

While there are encouraging results in small case series, cingulotomy, hypophysectomy, and mesencephalotomy deserve further detailed analysis.

Electrical neuromodulation is a rapidly changing discipline, and new methods such as high-frequency spinal cord stimulation (SCS), burst SCS, and dorsal root ganglion stimulation may or may not prove to be more effective than conventional SCS. Despite a history of failure, deep brain stimulation for pain may yet prove to be an effective therapy for specific pain conditions. Peripheral nerve stimulation for conditions such as occipital neuralgia and trigeminal neuropathic pain remains an option, although the quality of outcomes data is a challenge to these applications. Based on the evidence, motor cortex stimulation should be abandoned. TN is a mainstay of the surgical treatment of pain, particularly as new evidence and insights into TN emerge.

Pain surgery will continue to build on this heritage, and restorative procedures will likely find a role in the armamentarium. The challenge for the future will be to acquire higher-level evidence to support the practice of surgical pain management.

 

 

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Tentorial sling for microvascular decompression in patients with trigeminal neuralgia

J Neurosurg 130:1315–1320, 2019

Trigeminal neuralgia is a debilitating pain disorder most often caused by arterial compression of the trigeminal nerve, although there are other etiologies. Microvascular decompression (MVD) remains the most definitive treatment for this disorder, with cure rates reported between 60% and 80%. Traditional MVD techniques involve a retrosigmoid craniotomy with placement of an inert foreign material, such as Teflon, between the nerve and compressive vessel. Recurrence of trigeminal neuralgia after MVD has been associated with vessel migration, adhesion formation, and arterial pulsation against the Teflon abutting the nerve. Additionally, foreign materials such as Teflon have been reported to trigger inflammatory responses, resulting in recurrence of trigeminal pain. An alternative method for decompression involves the use of a sling to transpose the compressive vessel away from the nerve. Results of various sling techniques as a decompressive strategy are limited to small series and case reports. In this study, the authors present their experience utilizing a tentorial sling for MVD in patients with trigeminal neuralgia.

METHODS Institutional review board approval was obtained in order to contact patients who underwent MVD for trigeminal neuralgia via the tentorial sling technique. Clinical outcomes were assessed utilizing the Barrow Neurological Institute (BNI) pain intensity score immediately after surgery and at the time of the study.

RESULTS The tentorial sling technique was performed in 45 patients undergoing MVD for trigeminal neuralgia. In 41 of these patients, this procedure was their first decompressive surgery. Immediate postoperative relief of pain (BNI score I) was achieved in 80% of patients undergoing their first decompressive procedure. At last follow-up, 73% of these patients remained pain free. Three patients experienced recurrent trigeminal pain, with surgical exploration demonstrating an intact tentorial sling. The complication rate was 6.6%.

CONCLUSIONS Transposition techniques for MVD have been described previously in small series and case reports. This study represents the largest experience in which the utilization of a tentorial sling for MVD in patients with trigeminal neuralgia is described. The technique represents a novel method for decompression of the trigeminal nerve by transposition of the offending vessel without the use of foreign material. Although the authors’ preliminary results parallel the historical cure rate, further outcome data are required to assess long-term durability of this method.

 

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Trigeminal Nerve Atrophy Predicts Pain Recurrence After Gamma Knife Stereotactic Radiosurgery for Classical Trigeminal Neuralgia

Neurosurgery 84:927–934, 2019

Trigeminal nerve atrophy and neurovascular compression (NVC) are frequently observed in classical trigeminal neuralgia (CTN).

OBJECTIVE: To determine whether nerve characteristics contribute to Gamma Knife (ElektaAB, Stockholm, Sweden) surgery (GKS) outcomes in unilateral CTN without previous surgery.

METHODS: From 2006 to 2012, 67 patients with unilateral CTN without previous surgery received GKS with a maximal dose of 90 Gy delivered to the trigeminal nerve juxta brainstem. Two evaluators, blinded to the side of pain, analyzed the magnetic resonance images before GKS to obtain the parameters, including nerve cross-sectional area (CSA), vessel type of NVC, and site of NVC along the nerve. Correlations of the parameters with pain relief (Barrow Neurological Institute [BNI] grades I-IIIb) and recurrence (BNI grades VIV) were made by using Cox regression and Kaplan–Meier analyses.

RESULTS: The median CSA of the symptomatic nerves was significantly smaller than that of the asymptomatic nerves (4.95 vs 5.9 mm2, P < .001). After adjustment for age and sex, larger nerve CSA was associated with lower initial pain relief (hazard ratio 0.81, P=.03) and lower pain recurrence after initial response (hazard ratio 0.58, P= .02). Patients with nerve atrophy (CSA of ≤ 4.4 mm2 after receiver operating characteristic curve analysis) had a lower 5-yr probability of maintaining pain relief after initial response than those without nerve atrophy (65% vs 86%, P= .04).

CONCLUSION: Trigeminal nerve atrophy may predict pain recurrence in patients with initial post-GKS relief of CTN.Arterial and proximalNVCare not predictive ofGKS outcomes. Future studies are required to determine optimal treatments for long-term pain relief in patients with CTN and trigeminal nerve atrophy.

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The emerging role of gamma knife radiosurgery in the management of glossopharyngeal neuralgia

Neurosurg Rev (2019) 42:31–38

Glossopharyngeal neuralgia (GPN) represents a rare craniofacial disorder accounting for about 1% of all craniofacial pain syndromes. GPN shares several pathophysiologic and clinical features with the more common trigeminal neuralgia. Medical therapy and microvascular decompression, in case of vascular nerve compression, represented the mainstay of GPN management. Other ablative therapies have been reported to date; however, few data are available because of the rarity of this pain syndrome. Among the ablative procedures, gamma knife radiosurgery (GKRS) has been recently introduced in the management of GPN with good pain control and low complication rates.

Authors performed a systematic review of the published literature about GKRS in the management of GPN. Radiosurgical treatment data, pain control and recurrence rate have been analysed and compared.

GKRS represented a valuable and effective treatment option for the management of GPN. Pain control and complication rates are better than those reported by other ablative procedures and microvascular decompression; however, future studies should be focused on the long-term efficacy of GKRS.

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Stereotactic radiosurgery for trigeminal neuralgia: a systematic review

J Neurosurg 130:733–757, 2019

The aims of this systematic review are to provide an objective summary of the published literature specific to the treatment of classical trigeminal neuralgia with stereotactic radiosurgery (RS) and to develop consensus guideline recommendations for the use of RS, as endorsed by the International Society of Stereotactic Radiosurgery (ISRS).

METHODS

The authors performed a systematic review of the English-language literature from 1951 up to December 2015 using the Embase, PubMed, and MEDLINE databases. The following MeSH terms were used in a title and abstract screening: “radiosurgery” AND “trigeminal.” Of the 585 initial results obtained, the authors performed a full text screening of 185 studies and ultimately found 65 eligible studies. Guideline recommendations were based on level of evidence and level of consensus, the latter predefined as at least 85% agreement among the ISRS guideline committee members.

RESULTS

The results for 65 studies (6461 patients) are reported: 45 Gamma Knife RS (GKS) studies (5687 patients [88%]), 11 linear accelerator (LINAC) RS studies (511 patients [8%]), and 9 CyberKnife RS (CKR) studies (263 patients [4%]). With the exception of one prospective study, all studies were retrospective.

The mean maximal doses were 71.1–90.1 Gy (prescribed at the 100% isodose line) for GKS, 83.3 Gy for LINAC, and 64.3–80.5 Gy for CKR (the latter two prescribed at the 80% or 90% isodose lines, respectively). The ranges of maximal doses were as follows: 60–97 Gy for GKS, 50–90 Gy for LINAC, and 66–90 Gy for CKR.

Actuarial initial freedom from pain (FFP) without medication ranged from 28.6% to 100% (mean 53.1%, median 52.1%) for GKS, from 17.3% to 76% (mean 49.3%, median 43.2%) for LINAC, and from 40% to 72% (mean 56.3%, median 58%) for CKR. Specific to hypesthesia, the crude rates (all Barrow Neurological Institute Pain Intensity Scale scores included) ranged from 0% to 68.8% (mean 21.7%, median 19%) for GKS, from 11.4% to 49.7% (mean 27.6%, median 28.5%) for LINAC, and from 11.8% to 51.2% (mean 29.1%, median 18.7%) for CKR. Other complications included dysesthesias, paresthesias, dry eye, deafferentation pain, and keratitis. Hypesthesia and paresthesia occurred as complications only when the anterior retrogasserian portion of the trigeminal nerve was targeted, whereas the other listed complications occurred when the root entry zone was targeted. Recurrence rates ranged from 0% to 52.2% (mean 24.6%, median 23%) for GKS, from 19% to 63% (mean 32.2%, median 29%) for LINAC, and from 15.8% to 33% (mean 25.8%, median 27.2%) for CKR. Two GKS series reported 30% and 45.3% of patients who were pain free without medication at 10 years.

CONCLUSIONS

The literature is limited in its level of evidence, with only one comparative randomized trial (1 vs 2 isocenters) reported to date. At present, one can conclude that RS is a safe and effective therapy for drug-resistant trigeminal neuralgia. A number of consensus statements have been made and endorsed by the ISRS.

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Stereotactic Radiosurgery for Trigeminal Neuralgia in Patients With Multiple Sclerosis: A Multicenter Study

Neurosurgery 84:499–505, 2019

Facial pain response (PR) to various surgical interventions in patients with multiple sclerosis (MS)-related trigeminal neuralgia (TN) is much less optimal. No large patient series regarding stereotactic radiosurgery (SRS) has been published.

OBJECTIVE: To evaluate the clinical outcomes of MS-related TN treated with SRS.

METHODS: This is a retrospective cohort study. A total of 263 patients contributed by 9 member tertiary referral Gamma Knife centers (2 in Canada and 7 in USA) of the Interna- tional Gamma Knife Research Consortium (IGKRF) constituted this study.

RESULTS: The median latency period of PR after SRS was 1 mo. Reasonable pain control (Barrow Neurological Institute [BNI] Pain Scores I-IIIb) was achieved in 232 patients (88.2%). The median maintenance period from SRS was 14.1 months (range, 10 days to 10 years). The actuarial reasonable pain control maintenance rates at 1 yr, 2 yr, and 4 yr were 54%, 35%, and 24%, respectively. There was a correlation between the status of achieving BNI-I and the maintenance of facial pain recurrence-free rate. The median recurrence-free rate was 36 mo and 12.2 mo in patients achieving BNI-I and BNI > I, respectively (P = .046). Among 210 patients with known status of post-SRS complications, the new-onset of facial numbness (BNI-I or II) after SRS occurred in 21 patients (10%).

CONCLUSION: In this largest series SRS offers a reasonable benefit to risk profile for patients who have exhausted medical management. More favorable initial response to SRS may predict a long-lasting pain control.

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Effect of Bilateral Anterior Cingulotomy on Chronic Neuropathic Pain with Severe Depression

World Neurosurg. (2019) 121:196-200.

The presence of neuropathic pain can severely impinge on emotional regulation and activities of daily living including social activities, resulting in diminished life satisfaction. Unfortunately, the majority of patients with neuropathic pain do not experience an amelioration of symptoms from conventional therapies, even when multimodal therapies are used. Chronic refractory neuropathic pain is usually accompanied by severe depression that is prone to incur suicidal events; thus clinical management of chronic neuropathic pain and depression presents a serious challenge for clinicians and patients.

CASE DESCRIPTION: Two patients presented at our institution with neuropathic pain and severe depression. The patients had different pain symptoms emerging a few months after central or peripheral nervous system impairment. These symptoms were associated with the development of severe depression, social isolation, and a gradual inability to perform daily activities. Both patients were referred to our treatment center for bilateral anterior cingulotomy. After surgery, both patients showed significant progressive improvements in perceived pain, mental health status, and daily functioning. –

CONCLUSIONS: Bilateral anterior cingulotomy may serve as an alternative treatment for medically refractory neuropathic pain, especially for patients who also experience depression

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