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Daily bibliographic review of the Neurosurgery Department. La Fe University Hospital. Valencia, Spain

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.

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.

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.

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.

Hydrocephalus: an underrated long-term complication of microvascular decompression for trigeminal neuralgia

External lumbar drain- A pragmatic test for prediction of shunt outcomes in idiopathic normal pressure hydrocephalus

Acta Neurochir (2016) 158:2203–2206

Hydrocephalus is a common complication of posterior fossa surgery, but its real incidence after microvascular decompression (MVD) for idiopathic trigeminal neuralgia (TN) still remains unclear. The aim of this study was to focus on the potential association between MVD and hydrocephalus as a surgery-related complication.

Methods All patients who underwent MVD procedure for idiopathic TN at our institute between 2009 and 2014 were reviewed to search for early or late postoperative hydrocephalus.

Results There were 259 consecutive patients affected by idiopathic TN who underwent MVD procedure at our institution between 2009 and 2014 (113 men, 146 women; mean age 59 years, range 30–87 years; mean follow-up 40.92 months, range 8–48 months). Nine patients (3.47 %) developed communicating hydrocephalus after hospital discharge and underwent standard ventriculo-peritoneal shunt. No cases of acute hydrocephalus were noticed.

Conclusions Our study suggests that late communicating hydrocephalus may be an underrated potential long-term complication of MVD surgery.

 

Trigeminal and sphenopalatine ganglion stimulation for intractable craniofacial pain

Trigeminal and sphenopalatine ganglion stimulation for intractable craniofacial pain

Acta Neurochir (2016) 158:513–520

Facial pain is often debilitating and can be characterized by a sharp, stabbing, burning, aching, and dysesthetic sensation. Specifically, trigeminal neuropathic pain (TNP), anesthesia dolorosa, and persistent idiopathic facial pain (PIFP) are difficult diseases to treat, can be quite debilitating and an effective, enduring treatment remains elusive.

Methods We retrospectively reviewed our early experience with stimulation involving the trigeminal and sphenopalatine ganglion stimulation for TNP, anesthesia dolorosa, and PIFP between 2010–2014 to assess the feasibility of implanting at these ganglionic sites. Seven patients received either trigeminal and/or sphenopalatine ganglion stimulation with or without peripheral nerve stimulation, having failed multiple alternative modalities of treatment. The treatments were tailored on the physical location of pain to ensure regional coverage with the stimulation.

Results Fluoroscopy or frameless stereotaxy was utilized to place the sphenopalatine and/or trigeminal ganglion stimulator. All patients were initially trialed before implantation. Trial leads implanted in the pterygopalatine fossa near the sphenopalatine ganglion were implanted via transpterygoid (lateral-medial, infrazygomatic) approach. Trial leads were implanted in the trigeminal ganglion via percutaneous Hartel approach, all of which resulted in masseter contraction. Patients who developed clinically significant pain improvement underwent implantation. The trigeminal ganglion stimulation permanent implants involved placing a grid electrode over Meckel’s cave via subtemporal craniotomy, which offered a greater ability to stimulate subdivisions of the trigeminal nerve, without muscular (V3) side effects. Two of the seven overall patients did not respond well to the trial and were not implanted. Five patients reported pain relief with up to 24- month follow-up. Several of the sphenopalatine ganglion stimulation patients had pain relief without any paresthesias. There were no electrode migrations or post-surgical complications.

Conclusions Refractory facial pain may respond positively to ganglionic forms of stimulation. It appears safe and durable to implant electrodes in the pterygopalatine fossa via a lateral transpterygoid approach. Also, implantation of an electrode grid overlying Meckel’s cave appears to be a feasible alternative to the Hartel approach. Further investigation is needed to evaluate the usefulness of these approaches for various facial pain conditions.

Degree of distal trigeminal nerve atrophy predicts outcome after microvascular decompression for Type 1a trigeminal neuralgia

Trigeminal neuralgia due to neurovascular conflicts from venous origin- an anatomical-surgical study-1

J Neurosurg 123:1512–1518, 2015

Trigeminal neuralgia is often associated with nerve atrophy, in addition to vascular compression. The authors evaluated whether cross-sectional areas of different portions of the trigeminal nerve on preoperative imaging could be used to predict outcome after microvascular decompression (MVD).

Methods A total of 26 consecutive patients with unilateral Type 1a trigeminal neuralgia underwent high-resolution fast-field echo MRI of the cerebellopontine angle followed by MVD. Preoperative images were reconstructed and reviewed by 2 examiners blinded to the side of symptoms and clinical outcome. For each nerve, a computerized automatic segmentation algorithm was used to calculate the coronal cross-sectional area at the proximal nerve near the root entry zone and the distal nerve at the exit from the porus trigeminus. Findings were correlated with outcome at 12 months.

Results After MVD, 17 patients were pain free and not taking medications compared with 9 with residual pain. Across all cases, the coronal cross-sectional area of the symptomatic trigeminal nerve was significantly smaller than the asymptomatic side in the proximal part of the nerve, which was correlated with degree of compression at surgery. Atrophy of the distal trigeminal nerve was more pronounced in patients who had residual pain than in those with excellent outcome. Among the 7 patients who had greater than 20% loss of nerve volume in the distal nerve, only 2 were pain free and not taking medications at long-term follow-up.

Conclusions Trigeminal neuralgia is associated with atrophy of the root entry zone of the affected nerve compared with the asymptomatic side, but volume loss in different segments of the nerve has very different prognostic implications. Proximal atrophy is associated with vascular compression and correlates with improved outcome following MVD. However, distal atrophy is associated with a significantly worse outcome after MVD.

Trigeminal neuralgia due to neurovascular conflicts from venous origin: an anatomical-surgical study

Trigeminal neuralgia due to neurovascular conflicts from venous origin- an anatomical-surgical study-1

Acta Neurochir (2015) 157:455–466

Veins as the source of trigeminal neuralgias (TN) lead to controversies. Only a few studies have specifically dealt with venous implication in neurovascular conflicts (NVC). The aim of this study was the anatomical-surgical description of the compressive veins found during microvascular decompression (MVD).

Methods Patients retained were those in whom a vein was considered compressive, alone, or in association with an artery. The study defined the type of vein involved, its situation along, the location around the root, and management. For this study, denomination of veins in relation with the root was revisited.

Results Of the 326 consecutive patients who underwent MVD from 2005 to 2013, 124 (38.0 %) had a venous conflict, alone in 29 (8.9 %), or in association with an artery in 95 (29.1 %). The compressive veins belonged to one of the two venous systems described: the superficial or the deep superior petrosal venous system (sSPVS or dSPVS). A vein from sSPVS was found compressive in 81 cases (59.6 %), for the major part it was the pontine affluent of the superior petrosal vein (48 cases). The conflict was situated at TREZ in 28.4 %, midcisternal portion in 50.6 %, and porus in 8.6 %. The dSPVS was found compressive in 55 cases (40.4 %), almost always a transverse vein at porus (51 cases). Decompression was coagulation-division of the conflicting vein in 36.8 % and simple cleavage in the other.

Conclusions The study shows the frequent implication of veins in NVC as the source of TN. NVC are not only at TREZ but also at mid-cisternal portion and porus of Meckel cave.

Surgical Management of Trigeminal Neuralgia: Use and Cost-Effectiveness From an Analysis of the Medicare Claims Database

SnapShotPNGOID_38_20121112T070408_110023

Neurosurgery 75:220–226, 2014

Trigeminal neuralgia is a relatively common neurosurgical pathology with multiple management options. Microvascular decompression (MVD) is nonablative and is considered the gold standard. However, stereotaxic radiosurgery (SRS) and percutaneous stereotaxic rhizotomy (PSR) are 2 noninvasive but ablative options that have rapidly gained support.

OBJECTIVE: To use Medicare claims data in conjunction with a literature review to assess the usage, effectiveness, and cost-effectiveness of the 3 different invasive treatments for trigeminal neuralgia.

METHODS: All of the claims of trigeminal neuralgia treatment were extracted from the 2011 5% Inpatient and Outpatient Limited Data Set. Current Procedural Terminology, 4th Edition/International Classification of Diseases, Ninth Revision codes for the 3 different surgical treatment modalities were used to further classify these claims. Kaplan-Meier survival curves in key articles were used to calculate quality-adjusted life years and costeffectiveness for each procedure.

RESULTS: A total of 1582 claims of trigeminal neuralgia were collected. Ninety-four (6%) patients underwent surgical intervention. Forty-eight (51.1%) surgical patients underwent MVD, 39 (41.5%) underwent SRS, and 7 (7.4%) underwent PSR. The average weighted costs for MVD, SRS, and PSR were $40 434.95, $38 062.27, and $3910.64, respectively. The qualityadjusted life yearswere 8.2 forMVD, 4.9 for SRS, and 6.5 for PSR. The cost per quality-adjusted life year was calculated as $4931.1, $7767.8, and $601.64 for MVD, SRS, and PSR, respectively.

CONCLUSION: This study shows that the most frequently used surgical management of trigeminal neuralgia is MVD, followed closely by SRS. PSR, despite being the most cost-effective, is by far the least utilized treatment modality.

Retrogasserian balloon compression for treatment of trigeminal neuralgia. Series of 901 patients

RGBC

Surgical Neurology International 2014, 5:118

The aim of our study was to describe the retrogasserian balloon compression (RGBC) procedure with some personal tricks and to assess the long‑term results.

Methods: Between 1985 and 2012, 901 patients, suffering from refractory trigeminal neuralgia (TN), underwent RGBC procedure in our department. Concerning the surgical technique, the introducer was in close contact with the posterior extremity of the horizontal plate of the palatine bone and had the direction of the bisector of the angle clivus‑superior edge of the petrous bone on an X‑rays sagittal view. No metallic material was inserted intracranially. The balloon was inflated with 0.7 cc of contrast medium for 6 min.

Results: At 1 month follow up, appreciable pain relief was obtained in 835 patients (92.7%). At 1 year, results were excellent in 605 patients (67.1%), satisfactory in 109 patients (12.1%), poor in 57 patients (6.3%), fair in 66 patients (7.3%), whereas recurrences were observed in the remaining 64 patients (7.2%). At mean follow up of 16,5 years, 559 (62%) patients remained pain free. Twenty six patients (2,8%) continued to experience severe pain. Recurrences occurred in two hundred and fifty patients (27,8%). Fifty two of them were operated on a third time and 22 underwent four procedures.

Conclusion: RGBC is an appropriate and effective procedure for treatment of refractory TN, ensuring a long lasting pain relief predicted on three factors: pear shape of the balloon, its volume, and duration as mentioned earlier.

Repeat microvascular decompression for recurrent idiopathic trigeminal neuralgia

TN

DOI: 10.3171/2014.7.JNS132667

Microvascular decompression (MVD) is considered the method of choice to treat idiopathic trigeminal neuralgia (TN) refractory to medical treatment. However, repeat MVD for recurrent TN is not well established. In this paper, the authors describe a large case series in which patients underwent repeat MVD for recurrent TN, focusing on outcome, risk factors, and complication rates.

Methods. Between 1990 and 2012, a total of 33 consecutive patients underwent repeat MVD for recurrent TN at the University Medical Center Groningen. The authors performed a retrospective chart review and telephone interviews. Risk factors were analyzed by binary logistic regression analysis.

Results. After 12 months of follow-up, 22 (67%) operations were successful, of which 19 patients were completely free of pain without medication. With multivariate analysis significant risk factors for success were older age (OR 1.11, p < 0.01) and direct absence of pain after repeat MVD (OR 25.2, p < 0.01). Previous neurodestructive procedures did not influence success rates. Facial numbness occurred in 9 patients (27%), while other morbidity was minimal. There was no mortality.

Conclusions. This study demonstrates that repeat MVD is a feasible therapeutic option with good chances of success, even in patients who have undergone neurodestructive procedures. Complication rates, particularly facial numbness, can be avoided if only a limited neurolysis is performed.

Trigeminal nerve atrophy caused by neurovascular compression

Atrophic changes in the trigeminal nerves of patients with trigeminal neuralgia due to neurovascular compression and their association with the severity of compression and clinical outcomes

J Neurosurg 120:1484–1495, 2014

The aim of this study was to prospectively evaluate atrophic changes in trigeminal nerves (TGNs) using measurements of volume (V) and cross-sectional area (CSA) from high-resolution 3-T MR images obtained in patients with unilateral trigeminal neuralgia (TN), and to correlate these data with patient and neurovascular compression (NVC) characteristics and with clinical outcomes.

Methods. Anatomical TGN parameters (V and CSA) were obtained in 50 patients (30 women and 20 men; mean age 56.42 years, range 22–79 years) with classic TN before treatment with microvascular decompression (MVD). Parameters were compared between the symptomatic (ipsilateralTN) and asymptomatic (contralateralTN) sides of the face. Twenty normal control subjects were also included. Two independent observers blinded to the side of pain separately analyzed the images. Measurements of V (from the pons to the entrance of the nerve into Meckel’s cave) and CSA (at 5 mm from the entry of the TGN into the pons) for each TGN were performed using imaging software and axial and coronal projections, respectively. These data were correlated with patient characteristics (age, duration of symptoms before MVD, side of pain, sex, and area of pain distribution), NVC characteristics (type of vessel involved in NVC, location of compression along the nerve, site of compression around the circumference of the root, and degree of compression), and clinical outcomes at the 2-year follow-up after surgery. Comparisons were made using Bonferroni’s test. Interobserver variability was assessed using the Pearson correlation coefficient.

Results. The mean V of the TGN on the ipsilateralTN (60.35 ± 21.74 mm3) was significantly smaller (p < 0.05) than those for the contralateralTN and controls (78.62 ± 24.62 mm3 and 89.09 ± 14.72 mm3, respectively). The mean CSA of the TGN on the ipsilateralTN (4.17 ± 1.74 mm2) was significantly smaller than those for the contralateralTN and controls (5.41 ± 1.89 mm2 and 5.64 ± 0.85 mm2, respectively). The ipsilateralTN with NVC Grade III (marked indentation) had a significantly smaller mean V than the ipsilateralTN with NVC Grade I (mere contact), although it was not significantly smaller than that of the ipsilateralTN with NVC Grade II (displacement or distortion of root). The ipsilateralTN with NVC Grade III had a significantly smaller mean CSA than the ipsilateral TN with NVC Grades I and II (p < 0.05). The TGN on the ipsilateralTN in cured patients had a smaller mean CSA than that on the ipsilateralTN of patients with partial pain relief or treatment failure (p < 0.05). The same finding was almost found in relation to measurements of V, but the p value was slightly higher at 0.05.

Conclusions. Results showed that TGN atrophy in patients with TN can be demonstrated by high-resolution imaging. These data suggest that atrophic changes in TGNs, which significantly correlated with the severity of compression and clinical outcomes, may help to predict long-term prognosis after vascular decompression.

Trigeminal neuralgia occurs and recurs in the absence of neurovascular compression

NVC-TN

J Neurosurg 120:1048–1054, 2014

Vascular compression of the trigeminal nerve is the most common factor associated with the etiology of trigeminal neuralgia (TN). Microvascular decompression (MVD) has proven to be the most successful and durable surgical approach for this disorder. However, not all patients with TN manifest unequivocal neurovascular compression (NVC). Furthermore, over time patients with an initially successful MVD manifest a relentless rate of TN recurrence.

Methods. The authors performed a retrospective review of cases of TN Type 1 (TN1) or Type 2 (TN2) involving patients 18 years or older who underwent evaluation (and surgery when indicated) at Oregon Health & Science University between July 2006 and February 2013. Surgical and imaging findings were correlated.

Results. The review identified a total of 257 patients with TN (219 with TN1 and 38 with TN2) who underwent high-resolution MRI and MR angiography with 3D reconstruction of combined images using OsiriX. Imaging data revealed that the occurrence of TN1 and TN2 without NVC was 28.8% and 18.4%, respectively. A subgroup of 184 patients underwent surgical exploration. Imaging findings were highly correlated with surgical findings, with a sensitivity of 96% for TN1 and TN2 and a specificity of 90% for TN1 and 66% for TN2.

Conclusions. Magnetic resonance imaging detects NVC with a high degree of sensitivity. However, despite a diagnosis of TN1 or TN2, a significant number of patients have no NVC. Trigeminal neuralgia clearly occurs and recurs in the absence of NVC.

Vascular compression of the trigeminal nerve in asymptomatic individuals

Vascular compression of the trigeminal nerve in asymptomatic individuals

Acta Neurochir (2014) 156:577–580

Neurovascular compression (NVC) of the trigeminal nerve is associated with trigeminal neuralgia (TN), but also occurs in many asymptomatic individuals. The purpose of this study was to investigate the possible microstructural tissue changes of trigeminal nerves (TGN) in asymptomatic individuals with NVC by using axial diffusivity (AD) and radial diffusivity (RD) of MR imaging and to discuss its underlying mechanisms.

Methods Twenty asymptomatic individuals with unilateral NVC and 18 healthy controls (HCs) were divided into three groups (compressed, uncompressed side in asymptomatic individuals and HCs). Three groups were imaged with a 3.0-T MR system using three-dimensional fast imaging employing steady-state acquisition (3D FIESTA) and diffusion tensor imaging (DTI).We placed a region of interest over the root entry zone of the TGN and measured fractional anisotropy (FA), AD and RD. The mean values of FA, AD and RD were compared among the three groups.

Results No significant changes in any of the diffusion metrics (FA, RD and AD) were found among the three groups (compressed, uncompressed side in asymptomatic individuals and HCs).

Conclusions Our study demonstrated that neither demyelination nor axonal injury is found in asymptomatic individuals with NVC.

A Review of Percutaneous Treatments for Trigeminal Neuralgia

A Review of Percutaneous Treatments for Trigeminal Neuralgia

Operative Neurosurgery 10:25–33, 2014

Common treatments for trigeminal neuralgia include percutaneous techniques, microvascular decompression, and Gamma Knife radiosurgery. Although microvascular decompression is considered the gold standard for treatment, percutaneous techniques remain an effective option for select patients.

OBJECTIVE: To review the historical development, advantages, and limitations of the most common percutaneous procedures for trigeminal neuralgia: balloon compression (BC), glycerol rhizotomy (GR), and radiofrequency thermocoagulation (RF).

METHODS: Publications reporting clinical outcomes after BC, GR, and RF were reviewed and included. Operative technique was based on the experience of the primary surgeon and senior author.

RESULTS: All 3 percutaneous techniques (BC, GR, and RF) provide effective pain relief but differ in method and specificity of nerve injury. BC selectively injures larger pain fibers while sparing small fibers and does not require an awake, cooperative patient. Pain control rates up to 91% at 6 months and 66% at 3 years have been reported. RF allows somatotopic nerve mapping and selective division lesioning and provides pain relief in up to 97% of patients initially and 58% at 5 years. Multiple treatments improve outcomes but carry significant morbidity risk. GR offers similar pain-free outcomes of 90% at 6 months and 54% at 3 years but with higher complication rates (25% vs 16%) compared with BC. Advantages of percutaneous techniques include shorter procedure duration, minimal anesthesia risk, and in the case of GR and RF, immediate patient feedback.

CONCLUSION: Percutaneous treatments for trigeminal neuralgia remain safe, simple, and effective for achieving good pain control while minimizing procedural risk.

Role of endoscopy in the microvascular decompression for neurovascular conflicts in the cerebello-pontine angle

neurovascular conflict

Acta Neurochir (2013) 155:1709–1716

Microvascular decompression (MVD) is the surgical intervention designed to resolve neurovascular conflicts (NCs) in the cerebellopontine angle (CPA). Today, endoscopy is commonly used in many neurosurgical procedures. This study aims to retrospectively assess the usefulness of endoscopy during MVD, focusing on microscopic endoscopic-assisted (MEA) MVD.

Methods Between January 2010 and December 2012, 141 patients underwent MVD procedures: 119 (84.5 %) were affected by idiopathic trigeminal neuralgia (TN), 20 (14 %) by hemifacial spasm (HFS), 1 by glossopharyngeal neuralgia (GN) and 1 by TN and GN simultaneously; 128 (91 %) MVD were first time procedures, while 13 (9 %) were recurrences (10 TN, 3 HFS). Visualization techniques used were: pure microscopic in 89 (63 %) cases, fully endoscopic in 12 (8.5 %) and MEA in 40 (28.5 %). The MEA technique was used when the conflict was not clearly identified under microscopic view or it was not certainly resolved.

Results Overall, a NC was found in 130 (92 %) cases, while 11 patients had no intraoperative evidence of NC. Considering specifically the 40 MEA cases, 12 (8.5 % overall) conflicts not clearly visible with the microscope were revealed and solved, a complete conflict resolution was confirmed in 13 (9 % overall) cases, while an incomplete conflict resolution was shown in four cases (3 % overall).

Conclusion Pure microscopic MVD remains the technique of choice. The endoscope is a useful adjunctive imaging tool in confirming NCs identified by the microscope, revealing conflicts missed by the microscopic survey alone and verifying adequate nerve decompression.

Microvascular Decompression for Classic Trigeminal Neuralgia

MVD vascular compression

Neurosurgery 72:749–754, 2013

Outcomes studies use patient-reported outcome (PRO) measurements to assess treatment effectiveness, but can lack direct clinical meaning. Minimum clinically important difference (MCID) calculation provides a point estimate of the critical threshold needed to achieve clinically relevant treatment effectiveness. MCID remains uninvestigated for microvascular decompression (MVD), a common surgical procedure for trigeminal neuralgia. OBJECTIVE: We aimed to determine MCID for the most commonly used PRO measures of pain after MVD: Visual Analog Scale (VAS) and Barrow Neurological Institute Pain Scale (BNI-PS).

METHODS: Sixty consecutive patients with classic trigeminal neuralgia who decided to undergo MVD by a single surgeon were prospectively assessed with VAS and BNI-PS preoperatively and 2 years postoperatively. Three anchors were used to assign each patient’s outcome. We then used 3 well-established, anchor-based methods to calculate MCID.

RESULTS: Patients experienced significant improvement in both VAS (9.9 vs 2.0, P < .001) and BNI-PS (5.0 vs 1.9, P < .001) after MVD. The area under the receiver-operating characteristic curve was greater for BNI-PS than for VAS for all 3 anchors, indicating that BNI-PS is probably better suited for calculating MCID. The 3 MCID calculation methods generated a range of MCID values for each of the PROs (VAS: 1.40-8.87, BNI-PS: 0.95-3.26).

CONCLUSION: MVD-specific MCID is highly variable based on calculation technique. Some of these calculations appear to either overestimate or underestimate the patients’ preoperative expectations. When the different MCID methods are averaged, the results are clinically appropriate and consistent with preoperative expectations. The average MCID for VAS is 6.25 and for BNI-PS is 2.44.

The role of the cerebellopontine angle cistern area and trigeminal nerve length in the pathogenesis of trigeminal neuralgia

Role of CPA cistern and TN

Acta Neurochir (2013) 155:863–868

The aim of this prospective study was to evaluate whether the cerebellopontine angle (CPA) cistern area and trigeminal nerve cisternal length play a role in the pathogenesis of trigeminal neuralgia (TN).

Methods High-resolution 1.5 T magnetic resonance imaging of the posterior fossa was performed in 26 patients with TN and 18 age-matched healthy controls. Axial T2- weighted, three-dimensional constructive interference in steady-state (3D-CISS) was used to measure bilaterally the cross-sectional area of the CPA cistern and trigeminal nerve cisternal length.

Results In patients, the cross-sectional area of the CPA cistern and trigeminal nerve cisternal length was smaller on the affected side (p=0.04). Healthy controls tended to have larger cisternal areas and longer trigeminal nerve lengths than patients (p=0.059, p=0.071, respectively). Larger CPA cisternal areas tended to be seen in older patients. There was a strong correlation between the crosssectional area of the CPA cistern and the length of the trigeminal nerve (p=0.000).

Conclusions Smaller CPA cisterns and short cisternal trigeminal nerves impact the pathogenesis of essential TN by facilitating the neurovascular conflict, especially in younger patients. Trigeminal nerve cisternal measurement provides an easy and direct estimation of the CPA area. This information can be used for surgical planning and potentially for outcome prediction.

Glycerol rhizotomy and radiofrequency thermocoagulation for trigeminal neuralgia in multiple sclerosis

Print

J Neurosurg 118:329–336, 2013

Patients with trigeminal neuralgia due to multiple sclerosis (TN-MS) and idiopathic TN (ITN) who underwent glycerol rhizotomy (GR) and radiofrequency thermocoagulation with glycerol rhizotomy (RFTC-GR) were compared to investigate the effectiveness of these percutaneous ablative procedures in the TN-MS population.

Methods. Between 1998 and 2010, 822 patients with typical TN were evaluated; 63 (8%) had TN-MS and 759 (92%) had ITN. Pain relief comparisons were made between 22 GR procedures in patients with TN-MS and 470 GR procedures in patients with ITN; 50 RFTC-GR procedures in patients with TN-MS and 287 RFTC-GR procedures in patients with ITN were compared. Analysis of time to recurrence included only procedures that achieved complete pain relief without medications.

Results. After 15 of the GR procedures (68%) in patients with TN-MS and 315 of the procedures (67%) in those with ITN, the patients were pain free without medications (p = 0.736). After 36 of the RFTC-GR procedures (72%) in patients with TN-MS and 210 of the procedures (73%) in those with ITN, the patients were pain free without medications (p = 0.657). The difference in pain relief between GR and RFTC-GR for patients with TN-MS was not significant (p = 0.447). The median time to failure of GR was 20 months in patients with TN-MS compared with 25 months in those with ITN (p = 0.403). The median time to failure of RFTC-GR was 26 months in the TN-MS population compared with 21 months in the ITN population (p = 0.449). Patients with TN-MS experienced similar times to recurrence whether they were treated with GR or RFTC-GR (p = 0.431).

Conclusions. Pain relief and durability of relief outcomes of GR and RFTC-GR were similar in patients with TN-MS and ITN, reinforcing their use as preferred treatments of TN-MS. The GR and RFTC-GR achieved comparable outcomes in patients with TN-MS, suggesting that both can be used to good effect.

Patients with idiopathic trigeminal neuralgia have a sharper-than-normal trigeminal-pontine angle and trigeminal nerve atrophy

Acta Neurochir (2012) 154:1627–1633

Trigeminal neuralgia (TN) is primarily diagnosed by symptoms and patient history. Magnetic resonance (MR) imaging can be helpful in visualizing the neurovascular compression of the trigeminal nerve in TN patients, but the current parameters used as diagnostic markers for TN are less than optimal. The aim of this study is to assess whether the angle between the trigeminal nerve and the pons (the trigeminal-pontine angle) on the affected side of patients with idiopathic TN differs from that of the unaffected side and that found in controls without TN.

Methods A case-control study of 30 clinically diagnosed idiopathic TN patients aged 30 to 79 years and 30 age- and sexmatched controls was conducted.We compared the trigeminalpontine angle and trigeminal nerve atrophy via fast-imaging employing steady-state acquisition (FIESTA) MR imaging.

Results A sharp trigeminal-pontine angle was observed in 25 patients (25/30) on the affected side. As such, the mean angle of the trigeminal nerve on the affected side (40.17) was significantly smaller than that on the unaffected side (48.91, p=0.001) and that in the control group (52.02, p<0.001).

Conclusions A sharp trigeminal-pontine angle on the affected side was found in idiopathic TN patients by FIESTA imaging. This suggests that a sharp trigeminal-pontine angle increases the chance of neurovascular compression on the medial side of the trigeminal nerve.

Neurosurgery Department. “La Fe” University Hospital. Valencia, Spain

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