Category: Pain

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Older Patients Have Better Pain Outcomes Following Microvascular Decompression for Trigeminal Neuralgia

Neurosurgery 84:116–122, 2019

Trigeminal neuralgia (TN) increases in prevalence with age. Although microvascular decompression (MVD) is the most effective long-term operative treatment for TN, its use in older patient populations has been debated due to its invasive nature. Recent studies have demonstrated safety of MVD in older patients; however, efficacy data are more limited.

OBJECTIVE: To determine the relationship between age and pain outcomes following MVD for TN.

METHODS: Subjects underwent MVD for TN at our institution between 1/1/2004 and 12/31/2013, had typical TN, and demonstrated neurovascular compression on preoperative imaging.We performed a retrospective case series study by reviewing the electronic medical records and performing phone interviews to determine long-term outcomes. We divided patients into 2 groups for analysis, under 60 and 60 yr of age and older.

RESULTS: One hundred twenty-four subjects were included in the study, 82 under 60, and 42 60 yr of age and older. The average length of follow-up was 42.4 mo. Patients in the older age group had average pain score of 1.57 at most recent follow-up, while for the younger age group it was 2.18 (P = .0084). Multiple regression analysis found that older age, male gender, and preoperative medication responsiveness were significantly correlated with lower long-term pain scores, while V2 dermatome involvement was correlated with higher long-term pain scores.

CONCLUSION: Patients 60 yr of age and older have significantly better long-term pain outcomes following MVD than younger patients.

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Trigeminal Nerve Compression Without Trigeminal Neuralgia: Intraoperative vs Imaging Evidence

Neurosurgery 84:60–65, 2019

While high-resolution imaging is increasingly used in guiding decisions about surgical interventions for the treatment of trigeminal neuralgia, direct assessment of the extent of vascular contact of the trigeminal nerve is still considered the gold standard for the determination of whether nerve decompression is warranted.

OBJECTIVE: To compare intraoperative and magnetic resonance imaging (MRI) findings of the prevalence and severity of vascular compression of the trigeminal nerve in patients without classical trigeminal neuralgia.

METHODS: We prospectively recruited 27 patients without facial pain who were undergoing microvascular decompression for hemifacial spasm and had undergone highresolution preoperative MRI. Neurovascular contact/compression (NVC/C) by artery or vein was assessed both intraoperatively and by MRI, and was stratified into 3 types: simple contact, compression (indentation of the surface of the nerve), and deformity (deviation or distortion of the nerve).

RESULTS: Intraoperative evidence of NVC/C was detected in 23 patients. MRI evidence of NVC/Cwas detected in 18 patients, all ofwhomhad intraoperative evidence ofNVC/C. Thus, there were 5, or 28% more patients in whom NVC/C was detected intraoperatively than with MRI (Kappa = 0.52); contact was observed in 4 of these patients and compression in 1 patient. In patients where NVC/C was observed by both methods, there was agreement regarding the severity of contact/compression in 83% (15/18) of patients (Kappa=0.47). No patients exhibited deformity of the nerve by imaging or intraoperatively.

CONCLUSION: There was moderate agreement between imaging and operative findings with respect to both the presence and severity of NVC/C.

 

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Minimally Invasive Trigeminal Ablation: Novel Transoral Technique for Targeted Treatment of V3

World Neurosurg. (2018) 118:193-196

Trigeminal neuralgia (TN) is a chronic orofacial pain syndrome that presents with debilitating shooting pains in the V3 nerve distribution. The condition is traditionally responsive to anticonvulsant therapy; however, cases that become refractory to medications often require surgical intervention.

CASE DESCRIPTION: We present a case of TN that was treated with minimally invasive trigeminal ablation. The patient presented with a 6-year history of TN that had been resistant to medical management. The patient opted for minimally invasive management, refused stereotactic radiosurgery, and was treated using the minimally invasive trigeminal ablation approach. At 16 weeks postoperatively, the patient reported complete alleviation of pain with minimal sensorineural numbness.

CONCLUSIONS: The endoscopic approach allows for precise targeting through visual guidance, which is ideal in patients undergoing neuroablation for pain within specific nerve distributions. This is the first documented case of an endoscopic minimally invasive transoral approach toward ablative TN management.

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Electromagnetic neuronavigation for the percutaneous treatment of trigeminal neuralgia with balloon compression

Acta Neurochirurgica (2018) 160:1337–1341

Several techniques have been described for the percutaneous treatment of trigeminal neuralgia; however, each has significant drawbacks. We propose a new technique for percutaneous balloon compression of the trigeminal ganglion and distal trigeminal nerve using electromagnetic (EM) neuronavigation.

Methods The procedure was performed in 17 consecutive patients with trigeminal neuralgia. Patients were then followed up with telephone interview. We also performed a cadaveric validation study to further investigate the accuracy of the technique using dye.

Results Excellent clinical outcomes were achieved with a reduction in the median pain score from 10 out of 10 to 0 out of 10 following the procedure. The cadaveric study also demonstrated a high rate of foramen ovale cannulation.

Conclusion EM-based targeting of the foramen ovale and balloon inflation within Meckel’s cave is a quick, reproducible and straightforward technique for the percutaneous treatment of trigeminal neuralgia.

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Role of the petrous ridge and angulation of the trigeminal nerve in the pathogenesis of trigeminal neuralgia, with implications for microvascular decompression

Acta Neurochirurgica (2018) 160:971–976

Vascular compression is the main pathogenetic factor in apparently primary trigeminal neuralgia; however some patients may present with clinically classical neuralgia but no vascular conflict on MRI or even at surgery. Several factors have been cited as alternative or supplementary factors that may cause neuralgia. This work focuses on the shape of the petrous ridge at the point of exit from the cavum trigeminus as well as the angulation of the nerve at this point.

Methods Patients with trigeminal neuralgia that had performed a complete imagery workup according to our protocol and had microvascular decompression were included as well as ten controls. In all subjects, the angle of the petrous ridge as well as the angle of the nerve on passing over the ridge were measured. These were compared from between the neuralgic and the nonneuralgic side and with the measures performed in controls.

Results In 42 patients, the bony angle of the petrous ridge was measured to be 86° on the neuralgic side, significantly more acute than that of controls (98°, p = 0.004) and with a trend to be more acute than the non-neuralgic side (90°, p = 0.06). The angle of the nerve on the side of the neuralgia was measured to be on average 141°, not significantly different either from the other side (144°, p=0.2) or from controls (142°, p = 0.4). However, when taking into account the grade of the conflict, the angle was significantly more acute in patients with grade II/III conflict than on the contralateral side, especially when the superior cerebellar artery was the conflicting vessel.

Conclusion This pilot study analyzes factors other than NVC that may contribute to the pathogenesis of the neuralgia. It appears that aggressive bony edges may contribute—at least indirectly—to the neuralgia. This should be considered for surgical indication and conduct of surgery when patients undergo MVD.

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The relationship of dose to nerve volume in predicting pain recurrence after stereotactic radiosurgery in trigeminal neuralgia

J Neurosurg 128:891–896, 2018

Approximately 75%–92% of patients with trigeminal neuralgia (TN) achieve pain relief after Gamma Knife surgery (GKS), although a proportion of these patients will experience recurrence of their pain. To evaluate the reasons for durability or recurrence, this study determined the impact of trigeminal nerve length and volume, the nerve dose-volume relationship, and the presence of neurovascular compression (NVC) on pain outcomes after GKS for TN.

METHODS Fifty-eight patients with 60 symptomatic nerves underwent GKS for TN between 2013 and 2015, including 15 symptomatic nerves secondary to multiple sclerosis (MS). High-resolution MRI was acquired the day of GKS. The median maximum dose was 80 Gy for initial GKS and 65 Gy for repeat GKS. NVC, length and volume of the trigeminal nerve within the subarachnoid space of the posterior fossa, and the ratio of dose to nerve volume were assessed as predictors of recurrence.

RESULTS Follow-up was available on 55 patients. Forty-nine patients (89.1%) reported pain relief (Barrow Neurological Institute [BNI] Grades I–IIIb) after GKS at a median duration of 1.9 months. The probability of maintaining pain relief (BNI Grades I–IIIb) without requiring resumption or an increase in medication was 93% at 1 year and 84% at 2 years for patients without MS, and 68% at 1 year and 51% at 2 years for all patients. The nerve length, nerve volume, target distance from the brainstem, and presence of NVC were not predictive of pain recurrence. Patients with a smaller volume of nerve (< 35% of the total nerve volume) that received a high dose (≥ 80% isodose) were less likely to experience recurrence of their TN pain after 1 year (mean time to recurrence: < 35%, 32.2 ± 4.0 months; > 35%, 17.9 ± 2.8 months, log-rank test, c2 = 4.3, p = 0.039).

CONCLUSIONS The ratio of dose to nerve volume may predict recurrence of TN pain after GKS. Prospective studies are needed to determine the optimal dose to nerve volume ratio and whether this will result in longer pain-free outcomes.

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Quantitative study of the correlation between cerebellar retraction factors and hearing loss following microvascular decompression for hemifacial spasm

Acta Neurochir (2018) 160:145–150

This prospective study quantitatively measured the cerebellar retraction factors, including retraction distance, depth and duration, and evaluated their potential relationship to the development of hearing loss after microvascular decompression (MVD) for hemifacial spasm (HFS).

Methods One hundred ten patients with primary HFS who underwent MVD in our department were included into this study. The cerebellar retraction factors were quantitatively measured on preoperative MR and timed during MVD. Associations of cerebellar retraction and other factors to postoperative hearing loss were analyzed.

Results Eleven (10%) patients developed hearing loss after MVD. Compared with the group without hearing loss, the cerebellar retraction distance, depth and duration of the group with hearing loss were significantly greater (p < 0.05). Multivariate regression analysis showed that greater cerebellar retraction depth and longer retraction duration were significantly associated with a higher incidence of postoperative hearing impairment (p < 0.05).

Conclusion This study strongly suggested a correlation between the cerebellar retraction factors, especially retraction depth and duration, and possibility of hearing loss following MVD for HFS.

 

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Long-term follow-up of multimodality treatment for multiple sclerosis-related trigeminal neuralgia

Acta Neurochir (2018) 160:135–144

The treatment for multiple sclerosis-related trigeminal neuralgia (MS-TN) is less efficacious and associated with higher recurrence rates than classical TN. No consensus has been reached in the literature on the choice procedure for MS-TN patients. The aim of this study was to assess the incidence and surgical outcomes of medically refractory MS-TN.

Methods Patient records were retrospectively reviewed for all Manitobans undergoing first procedure for medically refractory MS-TN between 2000 and 2014. Subsequent procedures were then recorded and analyzed in this subgroup of patients. The primary outcome measure was time to treatment failure.

Results The incidence of medically refractory MS-TN was 1.2/million/year. Twenty-one patients with 26 surgically treated sides underwent first rhizotomy including 13 GammaKnife and 13 percutaneous rhizotomies comprised of ten glycerol injections and three balloon compressions. Subsequent procedures were required on 23 sides (88%), including 24 GammaKnife, 19 glycerol injections, 25 balloon compressions, two microvascular decompressions, and four open partial surgical rhizotomies with a total of 99 surgeries on 26 sides (range, 1–12 each).

Conclusions The majority of MS-TN patients become medically refractory and require multiple repeat surgical procedures. MS-TN procedures were associated with high rates of pain recurrence and our data suggests reoperation within 1 year is often necessary. Optimal management strategy in this patient population remains to be determined. Patients need to be counseled on managing expectations as treatments commonly afford only temporary relief.

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Intraoperative monitoring of sensory part of the trigeminal nerve using blink reflex during microvascular decompression for trigeminal neuralgia

Acta Neurochirurgica (2018) 160:165–169

Intraoperative monitoring during cerebellopontine angle surgery is widely accepted. While techniques which monitor cranial motor nerves are commonly used, monitoring the sensory afferents has been challenging. Considering the reflex arc, blink reflex (BR) might be useful in monitoring the sensory part of the trigeminal nerve, the brainstem connections and the facial nerve.

We describe the case of a patient who developed hemifacial hypoesthesia after microvascular decompression surgery for trigeminal neuralgia. Intraoperative BR showed a severe loss of R1 amplitude.

BR might be a useful intraoperative technique to monitor the sensory part of the trigeminal nerve.

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Prospective comparison of long-term pain relief rates after first-time microvascular decompression and stereotactic radiosurgery for trigeminal neuralgia

J Neurosurg 128:68–77, 2018

Common surgical treatments for trigeminal neuralgia (TN) include microvascular decompression (MVD), stereotactic radiosurgery (SRS), and radiofrequency ablation (RFA). Although the efficacy of each procedure has been described, few studies have directly compared these treatment modalities on pain control for TN. Using a large prospective longitudinal database, the authors aimed to 1) directly compare long-term pain control rates for first-time surgical treatments for idiopathic TN, and 2) identify predictors of pain control.

METHODS The authors reviewed a prospectively collected database for all patients who underwent treatment for TN between 1997 and 2014 at the University of California, San Francisco. Standardized collection of data on preoperative clinical characteristics, surgical procedure, and postoperative outcomes was performed. Data analyses were limited to those patients who received a first-time procedure for treatment of idiopathic TN with > 1 year of follow-up.

RESULTS Of 764 surgical procedures performed at the University of California, San Francisco, for TN (364 SRS, 316 MVD, and 84 RFA), 340 patients underwent first-time treatment for idiopathic TN (164 MVD, 168 SRS, and 8 RFA) and had > 1 year of follow-up. The analysis was restricted to patients who underwent MVD or SRS. Patients who received MVD were younger than those who underwent SRS (median age 63 vs 72 years, respectively; p < 0.001). The mean follow-up was 59 ± 35 months for MVD and 59 ± 45 months for SRS. Approximately 38% of patients who underwent MVD or SRS had > 5 years of follow-up (60 of 164 and 64 of 168 patients, respectively). Immediate or short-term (< 3 months) postoperative pain-free rates (Barrow Neurological Institute Pain Intensity score of I) were 96% for MVD and 75% for SRS. Percentages of patients with Barrow Neurological Institute Pain Intensity score of I at 1, 5, and 10 years after MVD were 83%, 61%, and 44%, and the corresponding percentages after SRS were 71%, 47%, and 27%, respectively. The median time to pain recurrence was 94 months (25th–75th quartiles: 57–131 months) for MVD and 53 months (25th–75th quartiles: 37–69 months) for SRS (p = 0.006). A subset of patients who had MVD also underwent partial sensory rhizotomy, usually in the setting of insignificant vascular compression. Compared with MVD alone, those who underwent MVD plus partial sensory rhizotomy had shorter pain-free intervals (median 45 months vs no median reached; p = 0.022). Multivariable regression demonstrated that shorter preoperative symptom duration (HR 1.005, 95% CI 1.001–1.008; p = 0.006) was associated with favorable outcome for MVD and that post-SRS sensory changes (HR 0.392, 95% CI 0.213–0.723; p = 0.003) were associated with favorable outcome for SRS.

CONCLUSIONS In this longitudinal study, patients who received MVD had longer pain-free intervals compared with those who underwent SRS. For patients who received SRS, postoperative sensory change was predictive of favorable outcome. However, surgical decision making depends upon many factors. This information can help physicians counsel patients with idiopathic TN on treatment selection.

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The tethered effect of the arachnoid in vago-glossopharyngeal neuralgia: a real associated alternative mechanism?

Acta Neurochir (2018) 160:151–155

Vago-glossopharyngeal neuralgia (VGPN) is a rarely seen disease when compared to trigeminal neuralgia. When the pain is resistant to medical therapy, microvascular decompression can be performed if a vascular conflict is suspected on magnetic resonance imaging (MRI). In addition, arachnoid pathology may play a role in VGPN. We report two cases of VGPN caused by tethered arachnoid, associated with a vascular contact in which pain was reduced by freeing rootlets from arachnoid compression.

We report two cases relating to 50-year-old and 30-year-old men with a history of electric shooting pain triggered by swallowing in the right pharyngeal and auricular regions. Preoperative MRI documented a neurovascular conflict in the first case and an arachnoid cyst in the second. Surgery was performed via a retrosigmoid craniotomy. In both cases, the intraoperative findings documented a tethered arachnoid membrane compressive to cranial nerves IX and X. Untethering was performed by liberation of the rootlets from the arachnoid with microvascular decompression. No additional rhizotomy was performed. The postoperative course was uneventful and pain was relieved in the first case and decreased in the second.

In VGPN, a tethered arachnoid may play a role in causing the neuralgia, either alone or associated with a neuro-vascular conflict.

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Microvascular decompression for glossopharyngeal neuralgia: a retrospective analysis of 228 cases

Acta Neurochir (2018) 160:117–123

Glossopharyngeal neuralgia (GPN) is an uncommon craniofacial pain syndrome caused by neurovascular conflict. Compared to trigeminal neuralgia or hemifacial spasm, the incidence of GPN was very low. Until now, little is known about the long-term outcome following microvascular decompression (MVD) process.

Methods Between 2006 and 2016, 228 idiopathic GPN patients underwent MVD in our department. Those cases were retrospectively reviewed with emphasis on intraoperative findings and long-term postoperative outcomes. The average period of follow-up was 54.3 ± 6.2 months.

Results Intraoperatively, the culprit was identified as the posterior inferior cerebellar artery (PICA) in 165 cases (72.3%), the vertebral artery (VA) in 14 (6.1%), vein in 10 (4.4%), and a combination of multiple arteries or venous offending vessels in 39 (17.2%). The immediately postoperative outcome was excellent in 204 cases (89.5%), good in 12 (5.3%), fair in 6 (2.6%) and poor in 6 (2.6%). More than 5-year follow-up was obtained in 107 cases (46.9%), which presented as excellent in 93 (86.9%), good in 6 (5.6%), fair in 3 (2.8%) and poor in 5 (4.7%). Thirty-seven (16.2%) of the patients experienced some postoperative neurological deficits immediately, such as dysphagia, hoarseness and facial paralysis, which has been improved at the last follow-up in most cases, except 2.

Conclusions This investigation demonstrated that MVD is a safe and effective remedy for treatment of GPN.

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Efficacy of deep rTMS for neuropathic pain in the lower limb: a randomized, double-blind crossover trial of an H-coil and figure-8 coil

J Neurosurg 127:1172–1180, 2017

Electrical motor cortex stimulation can relieve neuropathic pain (NP), but its use requires patients to undergo an invasive procedure. Repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex (M1) using a figure-8 coil can relieve NP noninvasively, but its ability to relieve lower limb pain is still limited. Deep rTMS using an H-coil can effectively stimulate deep brain regions and has been widely used for the treatment of various neurological diseases; however, there have been no clinical studies comparing the effectiveness of figure-8 coils and H-coils. This study assessed the clinical effectiveness of 5 once-daily stimulations with H-coils and figure-8 coils in patients with NP.

METHODS This randomized, double-blind, 3-way crossover trial examined 18 patients with NP who sequentially received 3 types of stimulations in the M1 for 5 consecutive days; each 5-day stimulation period was followed by a 17-day follow-up period before crossing over to the next type of stimulation. During each rTMS session, patients received a 5-Hz rTMS to the M1 region corresponding to the painful lower limb. The visual analog scale (VAS) and the Japanese version of the short-form McGill Pain Questionnaire 2 (SF-MPQ2-J) were used to measure pain intensity. The primary outcome was VAS score reduction immediately after and 1 hour after intervention.

RESULTS Both the VAS and SF-MPQ2-J showed significant pain improvement immediately after deep rTMS with an H-coil as compared with the sham group (p < 0.001 and p = 0.049, respectively). However, neither outcome measure showed significant pain improvement when using a figure-8 coil. The VAS also showed significant pain improvement 1 hour after deep rTMS with an H-coil (p = 0.004) but not 1 hour after rTMS using a figure-8 coil. None of the patients exhibited any serious adverse events.

CONCLUSIONS The current findings suggest that the use of deep rTMS with an H-coil in the lower limb region of the M1 in patients with NP was tolerable and could provide significant short-term pain relief.

Clinical trial registration no.: UMIN000010536 (http://www.umin.ac.jp/ctr/) https://thejns.org/doi/abs/10.3171/2016.9.JNS16815

 

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Long-term outcomes of microvascular decompression and Gamma Knife surgery for trigeminal neuralgia: a retrospective comparison study

Acta Neurochir (2017) 159:2127–2135

There is still no clear guideline for surgical treatment for patients with medically refractory trigeminal neuralgia (TN). When it comes to which surgical treatment to choose, microvascular decompression (MVD) or Gamma Knife surgery (GKS), we should know the long-term outcome of each treatment.

Methods We analyzed 179 patients undergoing MVD and 52 patients undergoing GKS followed for 1 year or longer. We evaluated the patient’s neurological status including pain relief, complications and recurrence. Results were assessed with Barrow Neurological Institute (BNI) pain intensity and facial numbness scores. Overall outcomes were compared between the two groups based on pain relief and complications.

Results BNI pain intensity and facial numbness scores at the final visit were significantly lower in the MVD group than in the GKS group (P < 0.001, P = 0.04, respectively). Overall outcomes were superior following MVD than following GKS (P < 0.001). Following whichever treatment, there were initially high rates of pain-free status “without medication”: 96.6% in the MVD group and 96.2% in the GKS group. However, 6.1% in the MVD group and 51.9% in the GKS group fell into a “with medication” state within median periods of 1.83 and 3.92 years, respectively (P < 0.001). Kaplan- Meier analysis revealed that pain recurred more often and later in the GKS group than in the MVD group (P < 0.001).

Conclusions Considering the long-term outcomes, MVD should be chosen as the initial surgical treatment for patients with medically refractory TN.

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Nerve atrophy in trigeminal neuralgia due to neurovascular compression and its association with surgical outcomes after microvascular decompression

Acta Neurochir (2017) 159:1699–1705

Idiopathic trigeminal neuralgia (TN) is caused by neurovascular compression and is often related to morphological changes in the trigeminal nerve. The aim of this study was to quantitatively measure atrophic changes of trigeminal nerves in patients with TN, and to further investigate whether nerve atrophy affected the efficacy of microvascular decompression (MVD).

Methods We conducted a prospective case-control study of 60 consecutive patients with TN and 30 sex- and age-matched healthy controls. All subjects underwent high-resolution three-dimensional MRI. The volume of the cisternal segment of trigeminal nerves was measured and compared using 3D Slicer software. Patients with TN underwent primary MVD and regular follow-up for at least 2 years. Associations of nerve atrophy with patient characteristics and operative outcomes were analyzed.

Results The mean volume of the affected trigeminal nerve was significantly reduced in comparison to that of the nonaffected side (65.8 ± 21.1 versus 77.9 ± 19.3 mm3, P = 0.001) and controls (65.8 ± 21.1 versus 74.7 ± 16.5 mm3, P = 0.003). Fifty-two patients (86.7%) achieved complete pain relief without medication immediately after surgery, and 77.6% of patients were complete pain relief at the 2-year follow-up. The Spearman correlation test showed that there was a positive correlation (r=0.46, P = 0.018) between the degree of trigeminal nerve indentation and nerve atrophy. In multivariate logistic regression analysis, two factors, indentation on nerve root (OR = 2.968, P = 0.022) and degree of nerve atrophy (OR = 1.18, P = 0.035), were associated with the long-term outcome.

Conclusions TN is associated with atrophy on the affected nerve. Furthermore, greater nerve atrophy is associated with more severe trigeminal nerve indentation and better long-term outcome following MVD.

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Trigeminal nerve contrast enhancement after radiosurgery

J Neurosurg 127:219–225, 2017

Contrast enhancement of the retrogasserian trigeminal nerve on MRI scans frequently develops after radiosurgical ablation for the management of medically refractory trigeminal neuralgia (TN). The authors sought to evaluate the clinical significance of this imaging finding in patients who underwent a second radiosurgical procedure for recurrent TN.

METHODS During a 22-year period, 360 patients underwent Gamma Knife stereotactic radiosurgery (SRS) as their first surgical procedure for TN at the authors’ center. The authors retrospectively analyzed the data from 59 patients (mean age 72 years, range 33–89 years) who underwent repeat SRS for recurrent pain at a median of 30 months (range 6–146 months) after the first SRS. The isocenter was 4 mm, and the median maximum doses for the first and second procedures were 80 Gy and 70 Gy, respectively. A neuroradiologist and a neurosurgeon blinded to the treated side evaluated the presence of nerve contrast enhancement on MRI series at the time of the repeat procedure. The authors correlated the presence of this imaging change with clinical outcomes. Pain outcomes and development of trigeminal sensory dysfunction were evaluated with the Barrow Neurological Institute (BNI) Pain Scale and BNI Numbness Scale, respectively. The mean length of follow-up after the second SRS was 58 months (95% CI 49–68 months).

RESULTS At the time of the repeat SRS, contrast enhancement of the trigeminal nerve on MRI scans was observed in 31 patients (53%). Five years after the SRS, patients with this enhancement had lower actuarial rates of complete pain relief after the repeat SRS (27% [95% CI 7%–47%]) than patients without the enhancement (76% [95% CI 58%–94%]) (p < 0.001). At the 5-year follow-up, patients with the contrast enhancement also had a higher risk for trigeminal sensory loss after repeat SRS (75% [95% CI 59%–91%]) than patients without contrast enhancement (26% [95% CI 10%–42%]) (p = 0.001). Dysesthetic pain after repeat SRS was observed for 8 patients with and for 2 patients without contrast enhancement.

CONCLUSIONS Trigeminal nerve contrast enhancement on MRI scans observed at the time of a repeat SRS for TN was associated with less satisfactory pain control and more frequently detected facial sensory loss. Residual contrast enhancement at the time of a repeat SRS may warrant consideration of dose reduction or further separation of the radiosurgical targets.

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Safety of Superior Petrosal Vein Sacrifice During Microvascular Decompression of the Trigeminal Nerve

WORLD NEUROSURGERY 103: 84-87, 2017

Microvascular decompression (MVD) is a safe and effective treatment for trigeminal neuralgia. Cerebellar venous infarction is a complication associated with surgical sacrifice of the superior petrosal vein (SPV). The SPV intervenes between the trigeminal nerve and the surgeon. Optimal exposure of the cisternal trigeminal nerve, particularly at the brainstem, can be achieved by sacrificing the SPV. We analyzed a cohort of 224 patients to determine the frequency of cerebellar venous infarction.

METHODS: Retrospective analysis of records and neuroradiology for patients undergoing trigeminal MVD at the Manchester Skull Base Unit between August 1st 2008 and July 31st 2015.

RESULTS: A total of 184 of 224 (82%) patients had coagulation and division of the main stem of the SPV. There were no cases of venous infarction. There was one case of mild, transient, cerebellar symptoms and signs, with no radiologic evidence of venous infarction. This patient had SPV sacrifice at surgery but also had postoperative thrombosis of the transverse sinus. Venous sinus thrombosis affected 5 of 184 (2.7%) patients. A total of 208 of 224 (93%) patients had a good outcome with improvement or resolution of their trigeminal neuralgia at 3 months.

CONCLUSIONS: The overall rate of venous complications in this study was 2.7%; however, we had no cases of venous infarction in 184 patients who had sacrifice of the SPV. The incidence of venous infarction associated with SPV obliteration during MVD surgery is therefore <0.5%. SPV sacrifice may be used where necessary to optimize visualization of the root entry zone and maximize the chance of effective decompression of the trigeminal nerve.

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Efficacy of primary microvascular decompression versus subsequent microvascular decompression for trigeminal neuralgia

J Neurosurg 126:1691–1697, 2017

Trigeminal neuralgia (TN) is characterized by intermittent, paroxysmal, and lancinating pain along the distribution of the trigeminal nerve. Microvascular decompression (MVD) directly addresses compression of the trigeminal nerve. The purpose of this study was to determine whether patients undergoing MVD as their first surgical intervention experience greater pain control than patients who undergo subsequent MVD.

METHODS A retrospective review of patient records from 1998 to 2015 identified a total of 942 patients with TN and 500 patients who underwent MVD. After excluding several cases, 306 patients underwent MVD as their first surgical intervention and 175 patients underwent subsequent MVD. Demographics and clinicopathological data and outcomes were obtained for analysis.

RESULTS In patients who underwent subsequent MVD, surgical intervention was performed at an older age (55.22 vs 49.98 years old, p < 0.0001) and the duration of symptoms was greater (7.22 vs 4.45 years, p < 0.0001) than for patients in whom MVD was their first surgical intervention. Patients who underwent initial MVD had improved pain relief and no improvement in pain rates compared with those who had subsequent MVD (95.8% and 4.2% vs 90.3% and 9.7%, respectively, p = 0.0041). Patients who underwent initial MVD had significantly lower rates of facial numbness in the pre- and postoperative periods compared with patients who underwent subsequent MVD (p < 0.0001). The number of complications in both groups was similar (p = 0.4572).

CONCLUSIONS The results demonstrate that patients who underwent other procedures prior to MVD had less pain relief and a higher incidence of facial numbness despite rates of complications similar to patients who underwent MVD as their first surgical intervention.

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Trigeminal neuralgia due to venous neurovascular conflicts

Acta Neurochir (2017) 159: 237

Implication of veins as neurovascular conflict (NVC) in the genesis of trigeminal neuralgia (TN) remains a matter of debate. Few reports dealing with venous NVC have been published. The objective of this study is to describe the outcome in a historical cohort of consecutive patients with classical TN due to venous compression.

Methods: All patients with TN treated by microvascular decompression (MVD) from 2005 to 2013 were included if a marked venous compression was found at the surgery either alone or accompanied by an artery. Patients were evaluated for clinical presentation, operative findings and the long-term outcome. Outcome was considered favourable if patients were classed as BNI I or II (i.e. not requiring any medication). Kaplan-Meier analysis was used to determine probability of a favourable outcome at 10 years of follow-up.

Results:  Out of the overall series of 313 patients having been treated by MVD and considered for the study, in 55 (17.5 %) a vein was the main compressive vessel; in 26 (8.3 %) it was the only compressive vessel. Probability of relief with no need for medication at 10 years was 70.6 %. The patients with focal arachnoiditis had a poor long-term outcome, i.e. BNI III-V, in 85.7 % compared with 20.8 % without arachnoiditis (p = 0.0037 Fisher’s exact test). No differences in outcome were found between patients presenting with purely venous compression and patients with mixed compression. Outcome was similarly good for patients with atypical neuralgia when compared to patients with typical clinical presentation.

Conclusions: Venous NVC as a cause of TN is far from rare. MVD with complete liberation of the entire root in cases with clear-cut venous compression on imaging studies gives a good probability of long-term pain relief, thus encouraging to propose surgery for such patients.

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Spinal Cord Stimulation for the Treatment of Chronic Back and Leg Pain

spinal-cord-stimulation-for-the-treatment-of-chronic-back-and-leg-pain

Neurosurgery 79:667–677, 201

Pain relief with spinal cord stimulation (SCS) has focused historically on paresthesias overlapping chronically painful areas. A higher level evidence supports the use of SCS in treating leg pain than supports back pain, as it is difficult to achieve adequate paresthesia coverage, and then pain relief, in the low back region. In comparison, 10-kHz high-frequency (HF10 therapy) SCS therapy does not rely on intraoperative paresthesia mapping and remains paresthesia-free during therapy. OBJECTIVE: To compare long-term results of HF10 therapy and traditional lowfrequency SCS.

METHODS: A pragmatic randomized, controlled, pivotal trial with 24-month follow-up was conducted across 11 comprehensive pain treatment centers. Subjects had Visual Analog Scale scores of$5.0/10.0 cmfor both back and leg pain, and were assigned randomly (1:1) to receive HF10 therapy or low-frequency SCS. The primary end point was a responder rate, defined as $50% back pain reduction from baseline at 3 months with a secondary end point at 12 months (previously reported). In this article, 24-month secondary results are presented. Non-inferiority was first assessed, and if demonstrated the results were tested for superiority.

RESULTS: In the study, 198 subjects were randomized (101 HF10 therapy, 97 traditional SCS). One hundred seventy-one subjects (90 HF10 therapy, 81 traditional SCS) successfully completed a short-term trial and were implanted. Subjects averaged 54.96 12.9 years old, 13.6 6 11.3 years since diagnosis, 86.6% had back surgery, 88.3% were taking opioid analgesics. At 3 months, 84.5% of implanted HF10 therapy subjects were responders for back pain and 83.1% for leg pain, and 43.8% of traditional SCS subjects were responders for back pain and 55.5% for leg pain (P , .001 for both back and leg pain comparisons, noninferiority and superiority). At 24 months, more subjects were responders to HF10 therapy than traditional SCS (back pain: 76.5% vs 49.3%; 27.2% difference, 95% CI, 10.1%-41.8%; P, .001 for non-inferiority and superiority; leg pain: 72.9% vs 49.3%; 23.6% difference, 95% CI, 5.9%-38.6%; P , .001 for non-inferiority and P = .003 for superiority). Also at 24 months, back pain decreased to a greater degree with HF10 therapy (66.9% 6 31.8%) than traditional SCS (41.1% 6 36.8%, P , .001 for non-inferiority and superiority). Leg pain also decreased to a greater degree with HF10 therapy (65.1% 6 36.0%) than traditional SCS (46.0% 6 40.4%, P , .001 for non-inferiority and P = .002 for superiority).

CONCLUSION: This study demonstrates long-term superiority of HF10 therapy compared with traditional SCS in treating both back and leg pain. The advantages of HF10 therapy are anticipated to impact the management of chronic pain patients substantially.

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