Tag: Microvascular decompression

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Fully endoscopic retrosigmoid approach for posterior petrous meningioma and trigeminal microvascular decompression

Fully endoscopic retrosigmoid approach for posterior petrous

Acta Neurochir (2015) 157:611–615

Cerebellopontine angle tumor resection and cranial nerve microvascular decompression are usually performed with the aid of the surgical microscope. The endoscope is commonly used as an adjuvant.

Method A retrosigmoid craniectomy is done. Upon dural opening, the endoscope is inserted into the operative field along the petrotentorial junction. Cerebrospinal fluid drainage provides a wider space for introduction of the endoscope and surgical instruments. Traditional microsurgical techniques are used during the entire procedure.

Conclusion A fully endoscopic retrosigmoid approach is a safe and effective procedure for cerebellopontine angle tumor resection and cranial nerve microvascular decompression.

Key points

• Careful examination of preoperative studies is needed to identify anatomical peculiarities.

• Patient positioning: the head must be gently flexed and its vertex gently tilted toward the floor.

• Neurophysiologic monitoring and intraoperative navigation.

• Craniectomy: partial exposure of the transverse and sigmoid sinuses.

• Curvilinear dural incision reflected laterally to minimize the risk of sinus injury.

• Opening the cerebellomedullary cistern for CSF drainage and cerebellar relaxation.

• Dynamic endoscopy enhances depth perception and must be performed by a team with experience in endoscopic intracranial surgery.

• Traditional microsurgical techniques have to be applied during the entire operation.

• Multilayer reconstruction, including watertight dural closure.

• Meningiomas causing brainstem shift are not suitable for endoscopic resection.

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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.

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Microvascular decompression under neuroendoscopic view in hemifacial spasm

Microvascular decompression under neuroendoscopic view in hemifacial spasm

Acta Neurochir (2015) 157:329–332

We report microvascular decompression (MVD) under neuroendoscopic view in hemifacial spasm (HFS) patients with rostral- and perforator-type compression of the root exit zone (REZ) of the facial nerve.

Using either a wireless iPad Mini as a monitor on the microscope or a high-resolution monitor, microscopic and endoscopic views enabled MVD for complete cure of HFS with rostral-type compression (the offender compressing the REZ on the opposite rostral side to the operative approach) or perforator-type compression (the offender tethered to the REZ by the perforator).

MVD under neuroendoscopic view may offer more accurate MVD and complete resolution of HFS.

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Vago-glossopharyngeal neuralgia

Vago-glossopharyngeal neuralgiaActa Neurochir (2015) 157:311–321

Glossopharyngeal neuralgia (GPN), or better named vago-glossopharyngeal neuralgia (VGPN), is a rare disorder amounting to 1 % of the incidence of trigeminal neuralgia (TN). Pain is paroxysmal, of the electrical shooting type, and mainly provoked by stimulation of the pharynx or deep throat, especially during swallowing. Due to its rarity, VGPN is often misdiagnosed. The front line of medical treatment is based on anticonvulsants. Surgery should be considered when the pain is refractory to medications. In most patients, the cause is neurovascular conflict on root entry zone (REZ) or midcistern portion, of the IXth and/or Xth cranial nerves. Compressive vessels can be evidenced by means of a high sensibility and a high specificity resolution MR imaging in most centers.

Present consensus is that the first option of neurosurgical treatment be microvascular decompression. In patients with precarious general conditions, stereotactic radiosurgery may be considered. Also, thermo-rhizotomy at the pars nervosa of foramen jugularis or tractotomy-nucleotomy at brainstem may be alternatives, but these methods entail a significant risk of deficits.

In this article, the authors reviewed the main literature series on neurosurgical treatments of this disease.

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Delayed relief of hemifacial spasm after microvascular decompression

Delayed relief of hemifacial spasm after microvascular decompression- can it be avoided?

Acta Neurochir (2015) 157:93–99

Although microvascular decompression (MVD) surgery has been widely accepted as an effective treatment for hemifacial spasm (HFS), delayed relief cases have been frequently reported. Therefore, the value of an immediate redo MVD should be discussed.

Methods This study included 1,435 HFS patients who underwent MVD with intraoperative abnormal muscle response (AMR) monitoring from 2011 through 2013 at XinHua Hospital. These cases were analyzed retrospectively with emphasis on the postoperative outcomes and introaperative findings.

Results After MVD, 1,384 HFS patients obtained relief immediately. The 51 unrelieved patients underwent AMR monitoring again the next day; this was positive in 48 and negative in 3 patients. These three patients with negative AMR obtained relief spontaneously within a week. Among the 48 positive patients, 31 and 11 were underwent redoMVD within a week and 5–22 months, respectively, and all achieved relief after the second operation. Of the six remainig patients, two obtained relief within 2months and 4 remained unchanged in the up-to- 3-year’s follow-up period. In redoMVDs, insufficient decompression of the facial nerve accounted for the failure. Finally, in this database, the immediate postoperative cure rate was 96.4 %; with earlier redo MVD, the final cure rate could be increased to 99.9 %.

Conclusions Despite being a reasonable remedy for HFS in the hands of an experienced neurosurgeon, sometimes small vessels can be missed while managing the main offending arteries during MVDs, which might account for the delayed relief. Therefore, reexamination of the AMR is necessary for unimproved patients; if a positive result is recorded, an immediate redo MVD is suggested.

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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.

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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.

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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.

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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.

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Follow-up results of the microvascular decompression operation for hemifacial spasm

FU of our microvascular decompression operation for HFS

Acta Neurochir (2013) 155:1693–1697

Microvascular decompression (MVD) for hemifacial spasm (HFS) has been popular, but it may take enough time to master this special operative technique and procedure. This may induce uneven distribution of the number of MVD operations in each institute, possibly resulting in an overall unsatisfactory quality of MVD surgeons. Nakanishi’s approach to MVD operations has the feature of using a, “supine, no retractor” technique, which would achieve various benefits for patients and medical professionals. We would like to recommend this approach for MVD surgeons on the basis of our follow-up outcomes.

Methods A questionnaire, which was based on the method of evaluation for the long-term results of post-MVD operation as recommended by the Japanese Society of MVD, was sent by mail to the 154 HFS patients who had received Nakanishi’s approach at our hospital.

Results Except for 42 patients who had changed their residences, 89 patients (79.5 % of 112) fully answered. The mean postoperative follow-up term was 13.0 years. The 76.4 % of the patients was estimated as excellent. Postoperative deafness was not present. The average value of satisfaction degree for the results of the MVD operation was 87.9 %.

Conclusions This study revealed that Nakanishi’s approach produced good results equivalent of other approaches for HFS patients. This approach is considered to have many advantages comparing to the other approaches. Therefore, we would like to recommend that Nakanishi’s approach would contribute to overall advancement of the level of MVD surgeons.

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Detecting the Offending Vessel in Hemifacial Spasm

Value of 3-Dimensional High-Resolution Magnetic Resonance Imaging in Detecting the Offending Vessel in Hemifacial Spasm

Neurosurgery 73:58–67, 2013

High-resolution 3-dimensional (3-D) magnetic resonance imaging (MRI) is widely used to predict the neurovascular anatomy within the cerebellopontine angle.

OBJECTIVE: To assess the value of 3-D steady-state free precession imaging (SSFP) and time-of-flight magnetic resonance angiography (TOF MRA) in detecting the offending vessels in hemifacial spasm in comparison to intraoperative endoscopic visualization.

METHODS: 42 patients underwent endoscope-assisted microvascular decompression (MVD). All available preoperative 3-D SSFP and TOF MRA images were checked. Intraoperative videos were captured by a high-definition endoscopic camera attached to endoscopes while exploring the area of facial nerve root exit zone (REZ). Evaluation of the 3-D images was performed by 2 independent groups of observers and compared with the operative findings.

RESULTS: Three-D MRI had an average positive predictive value (PPV) of 89.1% in differentiating between simple and complex compression. Mean accuracy of the images in detection of the offending vessels was 83.3% and 77% according to the first and second groups of observers, respectively. Averaged inter-observer agreement between the 2 groups of observers was substantial, with an averaged Kappa coefficient (K) of 0.56. In the simple compression group, mean accuracy was 97% and 89.4% according to the first and second groups of observers, respectively. Averaged K for agreement was substantial (K = 0.65).

CONCLUSION: According to endoscopic visualization, 3-D SSFP and TOF MRA images are accurate in detecting the offending vessels in simple compression of the facial nerve, and in predicting presence of a complex compression with variable sensitivity in identifying all offending vessels.

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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.

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Microvascular decompression for hemifacial spasm: long-term outcome and prognostic factors, with emphasis on delayed cure

PE-Hemifacial

Neurosurg Rev (2013) 36:297–302

The postoperative course of microvascular decompression (MVD) for hemifacial spasm (HFS) is variable, and the optimal time for assessing the results is unclear.

From April 1997 to October 2007, MVD for HFS was performed in 801 patients. Patients were divided into two groups (cured or failed) according to subjective patient assessments over a 3-year period. We analyzed patient characteristics and surgical findings to determine prognostic factors. Medical records were analyzed retrospectively over the 3-year follow-up period.

Of the 801 patients who underwent surgery, 743 (92.8 %) appeared to be cured, 70 (8.7 %) had residual or recurrent spasms more than 1 year after surgery, 11 (1.3 %) had gradual improvement over 3 years, and 1 (0.1 %) had delayed improvement more than 3 years after surgery. Fifty-eight patients (7.2 %) had residual or recurrent spasms more than 3 years after surgery, of which 19 (2.4 %) had recurrence after initial relief. The mean time to spasm recurrence was 18.9 months. Intraoperative resolution of the lateral spread response (LSR) after decompression (p=0.048) and severe indentation (p=0.038) were significant predictors of good long-term outcome after MVD for HFS.

In our series, 70 patients (8.7 %) had residual or recurrent spasms more than 1 year after surgery, of which 12 (17.1 %) improved gradually after 1 year. If the surgeon can confirm intraoperative resolution of the LSR and severe indentation, reoperation can be delayed until 3 years after MVD.

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Surgical technique for trigeminal microvascular decompression

Acta Neurochir (2012) 154:1089–1095 DOI 10.1007/s00701-012-1324-2

Microvascular decompression (MVD) is a non-ablative technique designed to resolve the neurovascular conflict responsible for typical idiopathic trigeminal neuralgia (TN).

Method With the patient in a supine position, a small elliptical retrosigmoid craniectomy is used to approach the cerebellopontine angle and the trigeminal nerve. After careful exploration of the trigeminal root entry zone, the offending vessel is identified and moved away. Oxidized regenerated cellulose is used to keep the vessel in its new position far from the nerve.

Conclusion MVD represents the gold standard first line treatment for TN; its aim is to free the nerve from any contact.

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Posterior Fossa Exploration for Trigeminal Neuralgia Patients Older Than 70 Years of Age

Neurosurgery 69:1255–1260, 2011 DOI: 10.1227/NEU.0b013e31822ba315

Patients with medically unresponsive trigeminal neuralgia (TN) who are >70 years of age often undergo operations that typically provide pain relief for <5 years despite having a life expectancy that can exceed 15 years.

OBJECTIVE: To review the safety and efficacy of posterior fossa exploration (PFE) for TN patients >70 years of age.

METHODS: From 1999 to 2009, 67 TN patients >70 years of age (median, 74 years) underwent a PFE. Thirty-seven patients (55%) had failed ≥1 prior surgeries (median, 2). Fifty-nine patients (88%) had a microvascular decompression, and 8 patients (12%) underwent a partial sensory rhizotomy. Follow-up (median, 40 months) was censored at the time of last contact (n = 51), additional surgery (n = 12), or death (n = 4).

RESULTS: Complete pain relief (no pain, no medications) was 87% at 1 year and 78% at 5 years. Facial pain outcomes did not correlate with patient age, sex, prior surgery, or pain duration. Postoperative complications were noted in 10 patients (15%) and included ataxia (10%), hearing loss (5%), trigeminal dysesthesias (5%), facial weakness (3%), aseptic meningitis (2%), and pulmonary embolus (2%). Factors associated with postoperative complications were prior PFE (P = .01) and neurovascular compression from a dolicoectatic basilar artery (P = .03).

CONCLUSION: Posterior fossa exploration is safe and effective for physiologically healthy TN patients .70 years of age. It should be deferred in older patients with TN secondary to a dolicoectatic basilar artery and patients who have persistent/recurrent pain after a previous PFE unless simpler procedures prove ineffective at controlling their facial pain.

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Visualization of Vascular Compression of the Trigeminal Nerve With High-Resolution 3T MRI: A Prospective Study Comparing Preoperative Imaging Analysis to Surgical Findings in 40 Consecutive Patients Who Underwent Microvascular Decompression for Trigeminal Neuralgia

Neurosurgery 69:15–26, 2011 DOI: 10.1227/NEU.0b013e318212bafa

High-resolution three-dimensional (3D) magnetic resonance imaging (MRI) has demonstrated its ability to predict fine trigeminal neurovascular anatomy.

OBJECTIVE: To address the predictive value of 3-Tesla (3T) MRI in detecting and assessing features of neurovascular compression (NVC), particularly regarding the degree of compression exerted on the root, in patients who underwent microvascular decompression (MVD) for classic primary trigeminal neuralgia.

METHODS: This prospective study includes 40 consecutive patients who underwent MVD for classic primary trigeminal neuralgia. All patients underwent a preoperative 3T MRI with 3D T2-weighted driven equilibrium (DRIVE), 3D time-of-flight (TOF) magnetic resonance angiography (MRA), and 3D T1-weighted gadolinium-enhanced sequences in combination. Evaluations were performed by 2 independent observers and compared with the operative findings.

RESULTS: For prediction of NVC, image analysis corresponded with surgical findings in 39 cases. Of the 3 patients in whom image analysis did not show NVC, 2 did not have NVC at the time of intraoperative observation. MRI sensitivity was 97.4% (37/38), and specificity was 100% (2/2). The kappa coefficients (k) for predicting the offending vessel, its location, and the site of compression were 0.882, 0.813, and 0.942, respectively. Image analysis correctly defined the severity of the compression in 31 of the 37 cases. The k coefficients predicting the degree of compression were 0.813, 0.833, and 0.852, respectively, for Grades 1 (simple contact), 2 (distortion), and 3 (marked indentation).

CONCLUSION: 3T MRI using 3D T2-weighted DRIVE in combination with 3D TOF-MRA and 3D T1-weighted gadolinium-enhanced sequences proved to be reliable in detecting NVC and in predicting the degree of root compression, the outcome being correlated with the latter.

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Stitched sling retraction technique for microvascular decompression: procedures and techniques based on an anatomical viewpoint

Neurosurg Rev (2011) 34:373–380. DOI 10.1007/s10143-011-0310-0

The success of microvascular decompression stitched sling retraction techniques for treating trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia (GPN), focusing on the stitching point for slinging the offending artery in the appropriate direction.

Between January 2007 and March 2009, 28 patients with TN, 5 patients with HFS, and 3 patients with GPN underwent MVD with a sling retraction technique. In cases of TN, MVD was performed using the infratentorial lateral supracerebellar approach, and the offending superior cerebellar artery was superomedially transposed with a sling stitched to the tentorium cerebelli. In cases of HFS, MVD was performed using the lateral suboccipital infrafloccular approach, and the offending vertebral artery was superolaterally transposed with a sling stitched to the petrous dura. In cases of GPN, MVD was performed using the transcondylar fossa approach, in which the posterior inferior cerebellar artery was inferolaterally mobilized with a sling secured to the jugular tubercle. No patient suffered recurrence in the follow-up period.

For the sling retraction technique to be performed successfully, it is important for a stitch to be placed at a suitable site to sling the offending vessel in the intended direction. An appropriate surgical approach must be used to obtain a sufficient operative field for performing the stitching procedures safely.

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Clinical features and surgical treatment of trigeminal neuralgia caused solely by venous compression

Acta Neurochir (2011) 153:1037–1042. DOI 10.1007/s00701-011-0957-x

Purpose To summarize our experience and lessons of microvascular decompression surgery for trigeminal neuralgia caused solely by venous compression.

Methods Fifteen patients with idiopathic trigeminal neuralgia caused by venous compression only underwent microvascular decompression. The entire course of the trigeminal root was explored thoroughly; and coagulating and cutting techniques were preferred in decompressing the culprit veins. Their clinical features, outcomes and operative complications were analyzed.

Results The compressing veins included the transverse pontine vein in five cases (33.3%), the transverse pontine vein and the vein of middle cerebellar peduncle in one (6.7%), the transverse pontine vein and the vein of cerebellopontine fissure in one (6.7%), the superior petrosal vein in three (20%), the pontotrigeminal vein in one (6.7%), the vein of the cerebellopontine fissure in two (13.3%), and the plexus venosus or venule in two (13.3%). After microvascular decompression, 11 cases (73.3%) had “excellent” or “good” pain relief. Four cases (26.7%) failed the first surgery; and two of them underwent re-operation and got “excellent” pain relief. Postoperative facial numbness appeared in four cases, due to injury to trigeminal nerve when coagulation.

Conclusion The transverse pontine vein is the most common offending vein. For this type of trigeminal neuralgia, coagulating and cutting techniques are preferred in decompressing the culprit veins. The entire course of the trigeminal root should be explored and decompressed. Following these principles, excellent or good pain relief could be achieved in most cases; and recurrence is rare. However, sometimes injury to the nerve is unavoidable when coagulating the culprit vein.

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Re-operation for persistent hemifacial spasm after microvascular decompression with the aid of intraoperative monitoring of abnormal muscle response

Acta Neurochir (2010) 152:2113–2118. DOI 10.1007/s00701-010-0837-9

Microvascular decompression (MVD) is the only solution that can effectively control hemifacial spasm (HFS). Regarding treatment of the patients who failed the first operation, it is still controversial. We tried to evaluate the safety and efficiency of the early re-exploration for such kinds of patients.

Methods Thirteen patients failed the first MVD and received a second MVD procedure. The spasm was not resolved at all or became even more severe after the first MVD. Abnormal muscle response (AMR) persisted during the first MVD operation or disappeared once but emerged again. The patient had a strong will to do the re-operation and was aware of the high risks of operative complications.

Results All the 13 patients got good or excellent spasm resolution immediately after the re-operation, which involved whole-range exploration and intraoperative AMR monitoring; however, there were two cases (15.4%) of permanent facial weakness and three cases (23.0%) of transient facial weakness.

Conclusions Our experience on early repeat MVD is whole-range exploration and intraoperative AMR monitoring; in other words, re-operation cannot rely too much on experience

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Surgical treatment of trigeminal neuralgia. Results from the use of glycerol injection, microvascular decompression, and rhizotomia

Acta Neurochir (2010) 152:2125–2132. DOI 10.1007/s00701-010-0840-1

The study aims to assess the efficacy and safety of surgical treatment of trigeminal neuralgia (TN) in our department and to identify prognostic factors.

Methods Seventy patients receiving surgical treatment for TN during the period 2003–2004 were included in this retrospective study. The surgical procedures used were glycerol injection (GI), microvascular decompression (MVD), or rhizotomia (RIZ). All patients were divided into spontaneous onset TN type1 (brief lancinating pain) or TN type 2 (continuous pain component). Two patients had bilateral TN; each side was regarded as a separate case. These 70 patients had a total of 160 interventions (110 GI, 40 MVD, and ten RIZ) performed in the period 1998–2007. Data were obtained by chart review and telephone interview. Patients provided information about pre- and postoperative pain characteristics including subtype, duration, intensity, and the use of antiepileptic drugs. Outcome was evaluated using a pain vector diagram.

Results To quantify self-reported pain, we developed a new vector-based pain diagram. The subtype of TN was shown to be a very important prognostic factor. One year after MVD, 90% of patients with type 1 TN still had positive effect, whereas this was only true in 73% of patients with type 2 TN. After RIZ, the results were 71% and 33% for types 1 and 2, respectively. For comparison, GI had a significant lower effect but if the treatment led to hypoesthesia, 41% continued to have a positive effect 1 year after surgery, compared to only 24% if postoperative sensation was normal. Type 2 TN was found to be dominated by women with left-sided TN outside the V2 dermatome and with a lower probability of a neurovascular conflict. As expected, 1/5 of the cases developed postoperative hypoesthesia in the face following a nerve destructive procedure (RIZ and GI). Using MVD, the risk of serious side effects was about 4%. Complementary and alternative treatment had no general or permanent effect in the investigated population—quite the contrary.

Conclusions Regarding prognosis and outcome, we find that it is very important to classify TN in subgroups (types 1 and 2). Dealing with medically treatment-resistant type 1 TN, MVD and RIZ are reasonably safe and effective interventions. The surgical results dealing with type 2 TN are still very poor. All patients with medically treatmentresistant TN should be offered referral to a neurosurgical unit with experience in treating this painful disease. We recommend using a vector-based pain diagram when evaluating the outcome of multiple interventions.

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