Microvascular decompression

Analyzing the Effect of Intraoperative Stimulation Voltage on Facial Numbness Following Radiofrequency Thermocoagulation in the Treatment of Idiopathic Trigeminal Neuralgia

INTRODUCTION

Radiofrequency thermocoagulation (RFT) effectively alleviates idiopathic trigeminal neuralgia (ITN); however, postoperative facial numbness poses a significant challenge. This issue arises due to the close proximity of high-temperature thermocoagulation, which not only ablates pain-related nociceptive fibers but also affects tactile fibers. Intraoperative sensory stimulation voltage (SV), which reflects the distance between the RFT cannula and the target nerve, potentially possesses the ability to prevent tactile fiber injury. This study aimed to investigate the influence of SV on postoperative facial numbness and provide valuable insights to mitigate its occurrence.

METHODS

A retrospective analysis was performed on 72 ITN patients with maxillary division (V2) pain who underwent RFT between 2020 and 2022. Among them, 13 patients with SV ≤ 0.2 V constituted the low SV group. Subsequently, a matched-cohort analysis was conducted on the remaining 59 patients. The patients paired with the low SV patients were subsequently enrolled in the high SV group, adhering to a 1:1 match ratio. The primary outcome was the facial numbness scale assessment at 3 days, 3 months and 6 months post-surgery. The pain intensity and medication burden served as the secondary outcomes.

RESULTS

We successfully matched a cohort consisting of 12 patients in the low SV group and 12 patients in the high SV group. Each patient experienced various degrees of facial numbness at 3 days post-RFT. Notably, the low SV group exhibited a higher incidence of moderate numbness (66.7% vs. 16.67%, P = 0.036), whereas the high SV group had more cases of mild numbness at the 6-month follow-up (25% vs. 83.3%, P = 0.012). Both groups demonstrated significant decreases in pain intensity and medication burden compared to before the operation.

CONCLUSIONS

SV proved to be a reliable parameter for mitigating the degree of postoperative facial numbness in RFT treatment for ITN. A relatively high sensory SV ranging from 0.3 to 0.6 V during the RFT procedure results in less facial numbness in the treatment of ITN.

Evaluating Changes in Pulsatile Flow With Endovascular Stents in an In Vitro Blood Vessel Model: Potential Implications for the Future Management of Neurovascular Compression Syndromes

BACKGROUND

Neurovascular compression syndromes (NVCS), encompassing conditions such as trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia, significantly impair patient quality of life through abnormal vascular compression and micro-pulsation of vasculature on cranial nerves at the Obersteiner-Redlich zone. The modulation of pulsatile flow dynamics via endovascular stents presents a novel research frontier for alleviating these syndromes.

AIM

The primary aim of this investigation was to delineate the impact of various endovascular stents on pulsatile flow within an in vitro model of a blood vessel, thereby elucidating their potential applicability in the therapeutic management of NVCS.

MATERIALS AND METHODS

A simple in vitro analog of a posterior circulation artery was developed, employing an intravenous pump to replicate cardiac-induced blood flow. Within this model, alterations in pulsatile flow were quantitatively assessed following the introduction of three categorically distinct endovascular stents, varying in size. This assessment was facilitated through the employment of both micro-Doppler and Doppler ultrasound methodologies.

RESULTS

The Pipeline 5x35 mm stent (Medtronic, Minneapolis, MN) demonstrated the most significant reductions in peak systolic velocity (Vmax) and pulsatility index (PI), PI especially over the stent, suggesting its potential for drastically altering blood flow dynamics. Similarly, Neuroform Atlas 4.5x30 mm and Neuroform Atlas 4x24 mm stents (Stryker, Kalamazoo, MI) also showed notable decreases in hemodynamic parameters, albeit to different extents. Statistical analysis confirmed that these changes were significantly different from the control (P < 0.0001 for PI and Vmax; P < 0.05 for inter-stent comparisons), except for proximal PI means, which did not significantly differ from the control (P = 0.2777).

CONCLUSION

These findings affirm the potential of endovascular stents to substantially modulate arterial pulsatility. The observed decrease in pulsatile flow resultant from endovascular stent application has the potential to attenuate ectopic nerve excitation, a hallmark of NVCS. Consequently, this research highlights the prospective utility of endovascular stents in developing minimally invasive therapeutic approaches for NVCS.

Predictors of Multi-Vessel Identification, Outcome, and Optimal Surgical Timing for Microvascular Decompression in Hemifacial Spasm

OBJECTIVES AND BACKGROUND

Hemifacial spasm (HFS) is a disabling condition that imposes significant burden upon patients. Microvascular decompression (MVD) surgery is the most effective and long-lasting treatment for HFS, but outcomes following this surgery may vary based on a variety of clinical and operative factors. A more thorough understanding of the variables that impact patient outcome after MVD surgery is needed.

METHODS

A systematic review and meta-analysis of Medline, Embase, and Central was conducted (n = 2108 screened; n = 86 included) with the goal of determining the impact of the following variables on outcome: duration of disease, geographic location, intraoperative use of an endoscope, and intraoperative finding of single versus multi-vessel neurovascular compression.

RESULTS

Most cases of hemifacial spasm occur on the left side (53.9%, p < 0.001) and are more common in women than men (66.5% versus 33.5%, p < 0.0001). The offending vessel frequencies were: 40.8% anterior inferior cerebellar artery [AICA], 24.9% posterior inferior cerebellar artery [PICA], 17.2% multiple vessels, and 4.7% vertebral artery [VA]. Multiple vessel combinations involved: 26.5% PICA + AICA, 24.6% PICA + VA, 23.1% AICA + VA, and 4.7% AICA + PICA + VA. Relative to the Americas, AICA was less frequent in Europe (p = 0.005), while PICA more frequent in Europe (p = 0.009) and Asia (p < 0.0001). With endoscope assistance, frequency of multiple vessels identified was 31.7% (versus 14.7% with non-endoscopic, p = 0.005), and 27.4% for AICA (43.5% with non-endoscopic, p = 0.003). Spasm improvement was 94.1% near discharge and 96.0% at maximum follow-up. Complications occurred in 16.5% of cases, with spasm recurrence in 2.4%. Greatest frequency of spasm improvement (p < 0.0001) and lowest spasm recurrence rates (p = 0.0005) were reported in series from Asia. For every additional month of pre-operative spasm, the effect size of post-operative improvement decreased (p = 0.04). With every subsequent postoperative month, the effect size of spasm improvement increased (p = 0.0497). The frequency of spasm improvement was significantly higher in series published after 2005 (94.4% versus 97.4%, p = 0.005).

CONCLUSION

Clinical outcomes following MVD for HFS have improved since 2005. Consideration should be given to earlier operation (shorter disease duration) and use of an endoscope may increase detection of multiple offending vessels. Further studies are needed to understand regional differences in culprit vessel incidence and surgical outcomes in the Americas, Europe, and Asia.

Routine postoperative admission to the neurocritical intensive care unit after microvascular decompression: necessary or can it be abandoned?

Postoperative neurocritical intensive care unit (NICU) admission of patients who underwent craniotomy for close observation is common practice. In this study, we performed a comparative analysis to determine if there is a real need for NICU admission after microvascular decompression (MVD) for cranial nerve disorders or whether it may be abandoned. The present study evaluates a consecutive series of 236 MVD surgeries performed for treatment of trigeminal neuralgia (213), hemifacial spasm (17), vagoglossopharyngeal neuralgia (2), paroxysmal vertigo (2), and pulsatile tinnitus (2). All patients were operated by the senior surgeon according to a standard protocol over a period of 12 years. Patients were admitted routinely to NICU during the first phase of the study (phase I), while in the second phase (phase II), only patients with specific indications would go to NICU. While 105 patients (44%) were admitted to NICU postoperatively (phase I), 131 patients (56%) returned to the ward after a short stay in a postanaesthesia care unit (PACU) (phase II). Specific indications for NICU admission in phase I were pneumothorax secondary to central venous catheter insertion (4 patients), AV block during surgery, low blood oxygen levels after extubation, and postoperative dysphagia and dysphonia (1 patient, respectively). There were no significant differences in the distribution of ASA scores or the presence of cardiac and pulmonary comorbidities like congestive heart failure, arterial hypertension, or chronic obstructive pulmonary disease between groups. There were no secondary referrals from PACU to NICU. Our study shows that routine admission of patients after eventless MVD to NICU does not provide additional value. NICU admission can be restricted to patients with specific indications. When MVD surgery is performed in experienced hands according to a standard anaesthesia protocol, clinical observation on a neurosurgical ward is sufficient to monitor the postoperative course. Such a policy results in substantial savings of costs and human resources.

The practical limits of high-quality magnetic resonance imaging for the diagnosis and classification of trigeminal neuralgia

BACKGROUND

Neurovascular compression (NVC) has been the primary hypothesis for the underlying mechanism of classical trigeminal neuralgia (TN). However, a substantial body of literature has emerged highlighting notable exceptions to this hypothesis. The purpose of this study is to assess the reliability and diagnostic accuracy of high resolution, high contrast MRI-determined neurovascular contact for TN.

METHODS

We performed a retrospective, randomized, and blinded parallel characterization of neurovascular interaction and diagnosis in a population of TN patients and controls using four expert reviewers. Performance statistics were calculated, as well as assessments for generalizability using shuffled bootstraps.

RESULTS

Fair to moderate agreement (ICC: 0.32-0.68) about diagnosis between reviewers was observed using MRIs from 47 TN patients and 47 controls. On average reviewers performed no better than chance when diagnosing participants, with an accuracy of 0.57 (95% CI 0.40, 0.59) per patient.

CONCLUSION

While MRI is useful in determining structural causes in secondary TN, expert reviewers do no better to only slightly better than chance with distinguishing TN with MRI, despite moderate agreement. Further, the causal role of NVC for TN is not clear, limiting the applicability of MRI to diagnose or prognosticate treatment of TN.

Percutaneous radiofrequency trigeminal rhizotomy benefits in patients with refractory trigeminal neuralgia

A significant number of patients suffers from refractory trigeminal neuralgia (TN) after receiving microvascular decompression (MVD) or other neuro-destructive procedure such as gamma knife radiosurgery (GKRS). This study aims to demonstrate a remediable, reproducible approach to treating refractory pain effectively by percutaneous radiofrequency trigeminal rhizotomy (RF-TR).A total of 392 patients with TN were treated by RF-TR during the past 10 years. Among these patients, 48 cases who had received either MVD, GKRS alone, or a combination of both were assigned to group A. Those who had not received any form of treatment (125 patients) or failed to respond medically (130 patients) were assigned as the control group (group B). All the RF-TR were performed by a single surgeon with the aid of intraoperative computed tomography (iCT)-based neuronavigation with magnetic resonance (MR) image fusion. The outcome measure was the numerical rating scale (NRS) expressed subjectively by patients. The paired Student t test and the analysis of covariance (ANCOVA) were used for statistical analysis.In group A, 21 of 24 patients (88%) had significant improvement (NRS change ≥5) in facial pain after RF-TR. The average NRS score was 9.75 ± 0.53 before the procedure and 1.92 ± 3.35 post-treatment (significant NRS decrease [P = .000]). On the other hand, in group B, 226 of 255 patients (89%) also had dramatic amelioration of facial pain after RF-TR. The average NRS score was 9.46 ± 0.69 before the procedure and 1.62 ± 2.85 post-treatment (7.84 ± 2.82 in NRS decrease [P = .008]). By using a univariate ANCOVA, no statistical significance was found in NRS score improvement between the two groups.Repeated MVD and GKRS for refractory TN may be less desirable due to a greater risk of mortality (up to 0.8%) and morbidity (4% of serious complications). Conversely, RF-TR administration with the novel navigation technique by using iCT and MR image fusion is free from any remarkable and irreversible morbidities. In this study, RF-TR not only provided an alternative and effective strategy if TN recurred but also resulted in the same NRS score improvement regardless of the status of prior treatment.

Concomitant continuous pain in patients with trigeminal neuralgia is associated with trigeminal nerve root atrophy

Introduction

Trigeminal neuralgia is an exemplary neuropathic pain condition characterized by paroxysmal electric-shock-like pain. However, up to 50% of patients also experiences concomitant continuous pain. In this neuroimaging study, we aimed to identify the specific anatomical features of trigeminal nerve root in patients with concomitant continuous pain.

Methods

We enrolled 73 patients with a definitive diagnosis of classical and idiopathic trigeminal neuralgia and 40 healthy participants. The diagnosis of trigeminal neuralgia was independently confirmed by two clinicians. Patients were grouped as patients with purely paroxysmal pain (45 patients) and patients also with concomitant continuous pain (28 patients). All participants underwent a structured clinical examination and a 3T MRI with sequences dedicated to the anatomical study of the trigeminal nerve root, including volumetric study. Images analysis was independently performed by two investigators, blinded to any clinical data.

Results

In most patients with concomitant continuous pain, this type of pain, described as burning, throbbing or aching, manifested at the disease onset. Demographic and clinical variables did not differ between the two groups of patients; the frequency of neurovascular compression and nerve dislocation were similar. Conversely, trigeminal nerve root atrophy was more severe in patients with concomitant continuous pain than in those with purely paroxysmal pain ( p = 0.006).

Conclusions

Our clinical and neuroimaging study found that in patients with trigeminal neuralgia, concomitant continuous pain was associated with trigeminal nerve root atrophy, therefore suggesting that this type of pain is likely related to axonal loss and abnormal activity in denervated trigeminal second-order neurons.

Combined pulsed and thermal radiofrequency versus thermal radiofrequency alone in the treatment of recurrent trigeminal neuralgia after microvascular decompression: A double blinded comparative study

BACKGROUND

Recurrent trigeminal neuralgia (RTN) is a common clinical problem and pain recurs in many patients after microvascular decompression (MVD). We evaluated the effect of adding pulsed radiofrequency to radiofrequency thermocoagulation at 60°C compared to radiofrequency thermocoagulation at 70°C alone in the treatment of recurrent trigeminal neuralgia after microvascular decompression.

METHODS

40 patients with recurrent trigeminal neuralgia after microvascular decompression were randomly divided into two equal groups. Group A: received prolonged duration of pulsed radiofrequency followed by less destructive thermocoagulation, while group B: received sole thermocoagulation. Then patients followed up for 2 years to evaluate the success rate by the Barrow Neurological Institute Pain Intensity (BNI) Scale, complications, and the need to medical treatment.

RESULTS

The success rate was 100% in both groups at discharge (BNI < III). It was 83.3% and 78.7% after 6 months, 77.8% and 68.4% after 12 month, 72.2% and 68.4% after 18 months and 66.7% and 63.1% after 24 months in group A and B, respectively (p > .05). In group A 88.9% of patients stopped tegretol treatment after the procedure compared to 84.2% in group B (p = .32). 88.9% compared to 89.5% % in group A and B, respectively, did not use tricyclic antidepressant (p = .61). The overall complications in group A was 5.61%, while it was 36.8% in group B (p = .025).

CONCLUSION

Combined pulsed and thermal radiofrequency can significantly reduce the incidence of the side effects/complications with similar success rate than using thermal radiofrequency alone in treatment of recurrent trigeminal neuralgia after microvascular decompression.

Immediate and Long-Term Outcomes of Microvascular Decompression for Mixed Trigeminal Neuralgia

BACKGROUND

Classic trigeminal neuralgia (TN) involves sharp, shooting pain in any trigeminal nerve distribution, whereas atypical TN presents with constant aching, numbness, or burning that can appear with classic features, leading to a mixed presentation. Microvascular decompression (MVD) is an effective treatment for classic TN, but its utility in treating mixed TN has been less well studied.

METHODS

We retrospectively studied 73 adult patients with mixed TN and 386 patients with classic TN who underwent MVD between December 2007 and October 2016. Recorded variables included demographic data, graded radiologic and intraoperative findings, and graded pain outcomes in the immediate postoperative period (up to 3 months after MVD) and during long-term follow-up.

RESULTS

The mean age of the 73 patients with mixed TN was 53.2 years. In terms of immediate postoperative outcomes, 67 patients (91.8%) experienced pain relief including improvement of atypical pain, whereas 6 patients (8.2%) had no pain relief. Having a preexisting pain syndrome (P = 0.001) or distortion of the trigeminal nerve intraoperatively (P = 0.001) was associated with poor surgical outcome in the patients with mixed TN. The mean duration of follow-up was 20.6 months. Forty-four patients (60.3%) developed recurrence of any TN pain. In comparison, 93% of the patients with classic TN experienced pain relief in the immediate postoperative period, and the recurrence rate was 19.9% in these patients.

CONCLUSIONS

Patients with mixed TN suffer from both classic and atypical TN symptoms. Following MVD, 91.8% of our patients with mixed TN reported partial or complete pain relief, including improvement of atypical pain, in the immediate postoperative stage, compared with 93% of those with classic TN. Recurrence eventually developed in 60.3% of the patients with mixed TN.

Flat Posterior Cranial Fossa Affects Outcomes of Microvascular Decompression for Trigeminal Neuralgia

OBJECTIVE

To investigate the prognostic factors for microvascular decompression (MVD) in patients with primary trigeminal neuralgia (TN), with a particular focus on the morphology of the posterior cranial fossa (PCF).

METHODS

The present study investigated 126 surgically treated patients with primary TN with more than 1-year follow-up who underwent high-resolution magnetic resonance imaging between April 2003 and September 2015. We retrospectively reviewed clinical information and operative findings. Outcomes of MVD were also evaluated and patients were classified into "success" and "failure" groups. Furthermore, length, width, and height of the PCF were measured by approximation to an ellipsoid with reference to the anterior commissure-posterior commissure line. These values were compared between groups.

RESULTS

Atypical type 2 TN (P < 0.001) and weak neurovascular compression (P < 0.001) correlated significantly with poor outcomes of MVD for primary TN. In terms of PCF morphology, the failure group showed a flatter PCF than the success group, whereas sex, age, affected side, topography of facial pain, interval between onset and surgery, responsible vessel, location of compression along the nerve, and site of compression around the circumference of the nerve root did not significantly affect outcomes of MVD for primary TN.

CONCLUSIONS

The present study identified type 2 TN, weak neurovascular compression, and flatness of the PCF as predictors of poor prognosis after MVD for primary TN.

Long-Term Efficacy of Nerve Combing for Patients with Trigeminal Neuralgia and Failed Prior Microvascular Decompression

BACKGROUND

Microvascular decompression (MVD) of the trigeminal nerve is the most effective treatment for trigeminal neuralgia (TN). However, many patients respond poorly to initial MVD. For these patients, redo MVD is commonly done. There has been no research regarding the effectiveness of nerve combing (NC) plus MVD in patients with TN and failed prior MVD. We compared the clinical outcome of NC plus MVD and simple redo MVD in patients with TN and failed prior MVD.

METHODS

We performed a retrospective analysis of 148 patients with recurrent or persistent TN symptoms who underwent surgery between January 2007 and December 2015. Simple MVD was performed in 62 patients, and NC plus MVD was performed in 86 patients.

RESULTS

For simple MVD, success rates at 1 day, 7 days, 1 month, 3 months, and 1 year after surgery all were approximately 80%. Success rates of NC plus MVD were significantly (P < 0.05) higher than success rates of simple MVD, by 17.02%, 18.64%, 16.47%, 17.21%, and 14.80% at 1 day, 7 days, 1 month, 3 months, and 1 year. The incidence rates of facial numbness in the simple MVD group were 48.39%, 45.16%, 36.67%, 16.95%, and 1.75% at 1 day, 7 days, 1 month, 3 months, and 1 year; the incidence rates in the NC plus MVD group were 60.47%, 55.81%, 48.24%, 21.69%, and 3.75% (P > 0.05).

CONCLUSIONS

In patients with TN who failed prior MVD, NC plus MVD significantly improved the success rate of the operation compared with simple redo MVD. We obtained good short-term and long-term surgical outcomes with NC combined with MVD.

Management of Recurrent Trigeminal Neuralgia Associated with Petroclival Meningioma

Objective Petroclival meningioma (PM) presents with trigeminal neuralgia (TN) in < 5% of cases. Neurosurgeons often face the dilemma of formulating a treatment protocol when TN recurs. In this study, we sought to set up a protocol in patients with PM who had a recurrent TN. Materials and Methods We performed a retrospective review of 57 patients with PM. Of the 57 patients, only 7 patients presented with TN, and six patients experienced recurrent TN. The study population was evaluated clinically and radiographically after treatment. Results Overall improvement of pain control after various treatments was 67%, and tumor control was 100%. The pain-free period was 2 years for the Gamma Knife radiosurgery (GKRS) group and 4 years for the resection group when treated as a primary treatment (p = 0.034). Of the six patients, four patients had Barrow Neurosurgical Institute (BNI) score I (no TN, no medication), and two patients had BNI score III (some pain controlled with medication). The Karnofsky performance scale score was significantly improved after treatment compared with the pretreated status (78 versus 88; p = 0.044). Conclusion Microsurgical resection is superior to GKRS in achieving and maintaining pain-free status in patients with recurrent trigeminal pain associated with PM.

CT-Guided Percutaneous Radiofrequency Thermocoagulation for Recurrent Trigeminal Neuralgia After Microvascular Decompression: A Cohort Study

This article evaluates the long-term outcomes of computed tomography (CT)-guided percutaneous radiofrequency thermocoagulation (PRT) for patients with recurrent trigeminal neuralgia (TN) after microvascular decompression (MVD).This is a retrospective study of 41 patients with intractable TN who after MVD underwent CT-guided PRT procedures between 2002 and 2012.The mean length of follow-up after PRT was 44.4 months. Immediate pain relief was in 37 patients (90.2%); the percentage of patients who remained in "excellent" or "good" pain relief condition after CT-guided PRT procedure was 85% at 1 year, 80% at 2 years, 51% at 5 years, and 41% at 10 years. Six patients received the second PRT and all achieved "excellent" or "good" pain relief. In total, 34 of these patients (82.9%) received multi-PRT procedure and remained satisfied with their pain relief during the follow-up period. Postoperative complications included facial numbness in 36 patients, limited eyes opening in 1 patient, ear paresthesia in 1 patient, no tears in 1 patient, and taste hypesthesia in 1 patient; these symptoms were all improved in the process of follow-up and their life had not severely affected. No mortality was observed during and after CT-guided PRT procedures.CT-guided PRT should be considered as an alternative treatment for patients with recurrent TN after MVD.

Long-term results of microvascular decompression for trigeminal neuralgia and hemifacial spasms according to preoperative symptomatology

BACKGROUND

Microvascular decompression (MVD) is currently used in several centres for the treatment of trigeminal neuralgia (TN) and hemifacial spasms (HFS). How long-term results relate to the preoperative symptoms still needs to be documented. The primary aim of this study was to assess long-term results of MVD for TN and HFS, as related to the types of preoperative symptoms.

METHODS

We performed a retrospective study including all first-time MVDs for TN and HFS done during the 11-year period (1999-2009) in the Department of Neurosurgery, The National Hospital (Rikshospitalet), Oslo. The patients were categorized depending on the pre-operative symptomatology.

RESULTS

The study population includes 303 first-time procedures performed by the senior author (PKE), 243 TN patients (65 % TN without constant pain and 35 % TN with constant pain) and 60 HFS patients (95 % typical HFS and 5 % atypical HFS). The patients were followed for a mean 71 months (range, 14-147). In both the TN and HFS patients, MVD caused lasting symptom relief in a high proportion of patients, including patients with atypical symptoms.

CONCLUSION

After MVD for TN and HFS, regardless of preoperative symptoms, lasting relief is observed in a high proportion of patients, with a favorable complication profile.

Decreased Rate of CSF Leakage Associated with Complete Reconstruction of Suboccipital Cranial Defects

Background Cerebrospinal fluid (CSF) leakage represents a major source of morbidity following microvascular decompression (MVD) surgery. The objective of this study was to retrospectively assess whether complete versus incomplete reconstruction of the suboccipital cranial defect influences the incidence of CSF leakage following MVD. Methods We reviewed the charts of 100 patients who consecutively underwent MVD for trigeminal neuralgia by two attending neurosurgeons between July 2004 and April 2010. Operative variables including incomplete or complete calvarial reconstruction, primary dural closure or dural closure with adjunct, and use of lumbar drainage were recorded. The effect of complete calvarial reconstruction on the incidence of postoperative CSF leakage was examined using a multivariate logistic regression model. Results Of the 36 patients whose wound closure was reconstructed with a complete cranioplasty, 2 (5.6%) patients experienced a postoperative CSF leak. Of the 64 patients whose wound closure was augmented with an incomplete cranioplasty, 15 (23.4%) experienced a postoperative CSF leak. There was suggestive but inconclusive evidence that the risk of CSF leakage following MVD was smaller with complete reconstruction of calvarial defect than with incomplete reconstruction (two-sided p value = 0.059), after accounting for age, dural closure method, use of lumbar drainage, and previous MVD. Conclusion Complete reconstruction of the suboccipital cranial defect decreases the risk of CSF leakage.

Comparative evaluation of surgical procedures for trigeminal neuralgia

Trigeminal neuralgia (TN) is a debilitating ailment. Pharmacotherapy still remains the first line therapy for the management of TN. However, often the patients become refractory to the pharmacotherapy and need surgical interventions. There is a wide array of surgical treatment modalities available for TN and it is important to select the most appropriate surgery for a patient. This review evaluates the various surgical modalities by employing a comparative analysis with respect to patient selection, success rate, complications and cost effectiveness. For the evaluation, a critical review of literature was done with predefined search terms to obtain the details of individual procedures, which were then compared, under similar parameters. The results suggested that microvascular decompression seem to be the most effective treatment in terms of patient satisfaction and long term cost effectiveness. However, if patient factors do not permit, then the peripheral procedures may be employed as a substitute, though they have higher recurrence rate and complications and have relatively lower long term cost effectiveness. The newer modalities like stereotactic radiosurgery and botulinum injections have promising results and further refinement in these procedures will provide additional options for the patients suffering from TN.

Long-term follow-up of microvascular decompression for trigeminal neuralgia

We conducted a study to evaluate the follow-up characteristics of patients with trigeminal neuralgia (TN) and to evaluate the factors affecting long-term outcome of microvascular decompression (MVD) in TN. Between 1983 and 2003, 156 patients with TN treated with MVD by 4 neurosurgeons at University Medical Centre Groningen/the Netherlands were evaluated. Baseline data from operative outcome were evaluated using univariate and multivariate analysis. The group consisted of 156 patients with TN: 90 females and 66 males with a median follow-up period of 9.7 years. The average age of initial symptoms was 51 years. The average duration of symptoms was 58 months. Postoperative 22 patients had a facial hyperpathia or hyperesthesia. Postoperatively, 137 patients had immediate relief. Postoperatively 1 year, 140 patients still had a good outcome of the operation. Twenty-seven patients with good immediate postoperative results had recurrent pain. From the group of patients with typical TN, 82% had good long-term results after operation. Patients with typical TN and immediate postoperative remission, in univariate analysis, had significantly more often an excellent/good postoperative outcome. Immediate postoperative remission is an independent predictive factor for a good long-term outcome. The long-term results of MVD in majority of patients were good with no mortalities and no major morbidities. Patients with typical TN had better long-term outcomes and less recurrence.

Microvascular decompression for trigeminal neuralgia in patients with and without prior stereotactic radiosurgery

BACKGROUND

Radiosurgery has emerged as an important primary treatment means of typical trigeminal neuralgia. Despite its high safety and efficacy, the likelihood of recurrence is significant, potentially requiring salvage treatment. Posterior fossa exploration and microvascular decompression is an option for salvage treatment. Results are presented regarding a single-surgeon experience, and a grading scale is proposed for postirradiation surgical findings.

METHODS

A retrospective analysis of the author's experience with 109 consecutive posterior fossa explorations for typical trigeminal neuralgia performed over a period of 8 years is included in this analysis. There were 42 patients undergoing microvascular decompression following recurrence of pain after radiosurgery, and 67 patients underwent microvascular decompression without prior radiosurgery. Operative findings were reviewed and categorized. A 4-category typing system is proposed. The Barrow Neurological Institute Pain Scale Score was used to categorize post-microvascular decompression outcomes.

RESULTS

Within the postradiosurgery group, 41 of 42 patients had initial treatment success (Barrow Neurological Institute score 1 to 3), comparing favorably with the nonirradiated group, in which 59 of 67 patients had initial successful treatment (P=0.15, Fisher exact test, 2-tailed). Findings of conflicting vessel atherosclerosis and adhesions between conflicting vessel and nerve were only seen in the postradiosurgery group, whereas arachnoid thickening requiring sharp dissection was seen in both postradiosurgery and nonirradiated groups. Increased difficulty of dissection in either the radiosurgery or the nonirradiated groups did not appear to affect the likelihood of satisfactory outcome.

CONCLUSIONS

Microvascular decompression can be performed in the postradiosurgery setting safely with high efficacy. Dissection typically was not significantly more difficult in comparison to procedures performed without prior history of radiosurgery intervention.

Motor cortex stimulation: functional magnetic resonance imaging–localized treatment for three sources of intractable facial pain

Neuropathic facial pain can be a debilitating condition characterized by stabbing, burning, dysesthetic sensation. With a large range of causes and types, including deafferentation, postherpetic, atypical, and idiopathic, both medicine and neurosurgery have struggled to find effective treatments that address this broad spectrum of facial pain. The authors report the use of motor cortex stimulation to alleviate 3 distinct conditions associated with intractable facial pain: trigeminal deafferentation pain following rhizotomy, deafferentation pain secondary to meningioma, and postherpetic neuralgia. Functional MR imaging was used to localize facial areas on the precentral gyrus prior to surgery. All 3 patients experienced long-lasting complete or near-complete resolution of pain following electrode implantation. Efficacy in pain reduction was achieved through variation of stimulation settings over the course of treatment, and it was assessed using the visual analog scale and narrative report. Surgical complications included moderate postsurgical incisional pain, transient cerebral edema, and intraoperative seizure. The authors' results affirm the efficacy and broaden the application of motor cortex stimulation to several forms of intractable facial pain.

The Treatment Outcome of Elderly Patients with Idiopathic Trigeminal Neuralgia : Micro-Vascular Decompression versus Gamma Knife Radiosurgery

OBJECTIVE

This study was designed to compare the efficacy of micro-vascular decompression (MVD) and Gamma knife radiosurgery (GKRS) for elderly idiopathic trigeminal neuralgia patients by analyzing the clinical outcome.

METHODS

In the past 10 years, 27 elderly patients were treated with MVD while 18 patients were treated with GKRS (>65-years-old). We reviewed their clinical characteristics and clinical courses after treatment as well as the treatment outcomes. For patients who were treated with MVD, additional treatment methods such as rhizotomy were combined in some areas. In GKRS, we radiated the root entry zone (REZ) with the mean maximum dose of 77.8 (70-84.3) Gy and one 4 mm collimator.

RESULTS

The mean age was 68.1 years for MVD, and 71.1 years for GKS group. The average time interval between first presenting symptom and surgery was 84.1 (1-361) months, and 51.4 (1-120) months, respectively. The mean follow-up period after the surgery was 35.9 months for MVD, and 33.1 months for GKRS. According to Pain Intensity Scale, MVD group showed better prognosis with 17 (63%) cases in grade I-II versus 10 (55.6%) cases in GKRS group after the treatment. The pain recurrence rate during follow up did not show much difference with 3 (11.1%) in MVD, and 2 (11.1%) in GKRS. After the treatment, 2 cases of facial numbness, and 1 case each of herpes zoster, cerebrospinal fluid (CSF) leakage, hearing disturbance, and subdural hematoma occurred in MVD Group. In GKRS, there was 1 (5.6%) case of dysesthesia but was not permanent. Three cases were retreated by GKRS but the prognosis was not as good as when the surgery was used as primary treatment, with 1 case of grade I-II, and 1 case of recurrence. The maximal relieve of pain was seen just after surgery in MVD group, and 1 year after treatment in GKRS group.

CONCLUSION

For trigeminal neuralgia patients with advanced age, MVD showed advantages in immediately relieving the pain. However, in overall, GKRS was preferable, despite the delayed pain relief, due to the lower rate of surgical complications that arise owing to the old age.

Perioperative and long-term operative outcomes after surgery for trigeminal neuralgia: microvascular decompression vs percutaneous balloon ablation

Objectives

Numerous medical and surgical therapies have been utilized to treat the symptoms of trigeminal neuralgia (TN). This retrospective study compares patients undergoing either microvascular decompression or balloon ablation of the trigeminal ganglion and determines which produces the best long-term outcomes.

Methods

A 10-year retrospective chart review was performed on patients who underwent microvascular decompression (MVD) or percutaneous balloon ablation (BA) surgery for TN. Demographic data, intraoperative variables, length of hospitalization and symptom improvement were assessed along with complications and recurrences of symptoms after surgery. Appropriate statistical comparisons were utilized to assess differences between the two surgical techniques.

Results

MVD patients were younger but were otherwise similar to BA patients. Intraoperatively, twice as many BA patients developed bradycardia compared to MVD patients. 75% of BA patients with bradycardia had an improvement of symptoms. Hospital stay was shorter in BA patients but overall improvement of symptoms was better with MVD. Postoperative complication rates were similar (21% vs 26%) between the BA and MVD groups.

Discussion

MVD produced better overall outcomes compared to BA and may be the procedure of choice for surgery to treat TN.

Trigeminal neuralgia: for one nerve a multitude of treatments

Trigeminal neuralgia (TN) is reputed to be one of the most painful conditions in human experience. Thus, many treatments, both medical and surgical, have been developed for this relapsing and remitting, paroxysmal stabbing or electrical, facial pain syndrome. The likely etiology in many cases is vascular compression of the trigeminal nerve root entry zone, leading to focal demyelination and aberrant neural discharges. MRI may disclose neurovascular contact, although not with sufficient sensitivity or specificity to substitute for careful clinical diagnosis. In treating TN, antiepileptic drugs are superior to traditional analgesics. Carbamazepine is the first choice drug. Additional drugs for which there is evidence of efficacy include oxcarbazepine, baclofen, gabapentin, lamotrigine and phenytoin. Many patients eventually experience tachyphylaxis or may not tolerate effective doses. Surgical options include: microvascular decompression; balloon compression; radiofrequency thermocoagulation or glycerol rhizotomies; and subcutaneous alcohol branch blockade. Stereotactic gamma knife radiosurgery is a further option. Motor cortex stimulation and transcranial magnetic stimulation, although having shown initial promise for trigeminal neuropathic pain, seem to be ineffective for classical TN. The choice of drug, whether or when to operate, and which procedure to choose should be individualized to the particular needs and conditions of the patient.

Trigeminal neuralgia

The paroxysmal facial pain of trigeminal neuralgia is notoriously severe. Recent advances in medical science are achieving significant strides toward alleviating this incapacitating condition. High-resolution neuroimaging techniques are rendering detailed views of underlying neurovascular relationships. Newer antiepileptic medications and novel therapies are proving helpful in treating pain resistant to carbamazepine. Further developments also in targeted neurosurgical and radiosurgical techniques are providing pain relief within increasingly wider margins of safety. Much has been accomplished, yet much remains to be done.

Mechanisms of neuropathic pain

Neuropathic pain refers to pain that originates from pathology of the nervous system. Diabetes, infection (herpes zoster), nerve compression, nerve trauma, "channelopathies," and autoimmune disease are examples of diseases that may cause neuropathic pain. The development of both animal models and newer pharmacological strategies has led to an explosion of interest in the underlying mechanisms. Neuropathic pain reflects both peripheral and central sensitization mechanisms. Abnormal signals arise not only from injured axons but also from the intact nociceptors that share the innervation territory of the injured nerve. This review focuses on how both human studies and animal models are helping to elucidate the mechanisms underlying these surprisingly common disorders. The rapid gain in knowledge about abnormal signaling promises breakthroughs in the treatment of these often debilitating disorders.

Orofacial Pain—Part I

Orofacial pain is a common complaint, affecting the lives of millions of people around the world. Chronic orofacial pain often constitutes a challenging diagnostic problem that can be complicated by psychosocial factors and typically requires multidisciplinary treatment approaches. The fundamental prerequisite for successful management of orofacial pain is an accurate diagnosis. Generating a differential diagnosis, which will ultimately lead to a definite diagnosis, requires thorough knowledge of the diagnostic range of orofacial pain. There is a vast array of orofacial pain categories including: (1) musculoskeletal, (2) neuropathic, (3) vascular, (4) neurovascular, (5) idiopathic, (6) pain caused by local, distant, or systemic pathology, and (7) psychogenic. This article presents the salient clinical features and the therapeutic approaches for the various subtypes of musculoskeletal and neuropathic pain. Musculoskeletal pain is the most prevalent orofacial pain, with temporomandibular disorders and tension-type headache being the main examples. Neuropathic pain develops secondary to neural injury and/or irritation and can be distinguished into episodic, including trigeminal neuralgia and glossopharyngeal neuralgia, as well as continuous, such as herpetic and postherpetic neuralgia, traumatic neuralgia, and Eagle's syndrome.

Trigeminal neuralgia in a patient with multiple sclerosis and chronic inflammatory demyelinating polyneuropathy

BACKGROUND

Trigeminal neuralgia (TN) is characterized by unilateral, severe, brief, stabbing, recurrent pain in the distribution of one or more branches of the fifth cranial nerve. Symptomatic or secondary TN involves TN-like pain that develops owing to a central nervous system lesion (benign or malignant) or to multiple sclerosis (MS).

CASE DESCRIPTION

The authors present a report of a unique case of a 43-year-old patient with unilateral TN, MS and concomitant chronic inflammatory demyelinating polyneuropathy. The facial pain preceded any other manifestations of the systemic disorders, and only after repeated neurological examinations were these diagnoses established.

CLINICAL IMPLICATIONS

Magnetic resonance imaging of the brain and repeated neurological evaluations should be implemented in all patients with TN to rule out the presence of underlying disease. The dental practitioner should be familiar with TN to avoid unnecessary dental interventions and ensure prompt initiation of appropriate treatment.

Trigeminal neuralgia: Diagnosis and treatment

Trigeminal neuralgia is considered to be one of the most severe forms of pain in the human experience. In this discussion, classical neurology, current advances in medical science, and the relief of human suffering converge in a single nerve. Improvements in the resolution of neuroimaging have elucidated neurovascular relationships in striking detail. The availability of new antiepileptic medications has expanded the range of therapeutic options for patients whose pain cannot be controlled by first-line agents. Further developments in neurosurgical and radiosurgical techniques have provided effective treatments with increasingly wider margins of safety. Significant advances in cortical stimulation technology are also making headway into pain relief and delineating the central mechanisms of chronic neuropathic pain.

Long-Term Follow-Up of Trigeminal Neuralgia Treatment Using a Linear Accelerator

While most of the studies examining radiosurgery for trigeminal neuralgia have used a Gamma Knife, a linear accelerator can also be utilized for treatment. We report on 20 patients with trigeminal neuralgia who received 23 treatments with a linear accelerator that delivered a maximum dose of 82.3-100 Gy. The median patient follow-up was 56.5 months, 70% of patients had received previous surgical treatment and 20% had secondary (nonessential) trigeminal neuralgia. Eight (35%) radiosurgery treatments resulted in complete pain relief; 5 (63%) patients with initial pain relief had pain recurrence at a mean time of 21.5 months. Ten (43%) patients reported a 50% or more decrease in pain severity but have not achieved a pain-free state. A total of 18 (78%) treatments resulted in no pain or a 50% or greater improvement in pain. Five treatments (22%) resulted in less than 50% improvement in pain. We conclude that linear accelerator stereotactic radiosurgery is a viable treatment option for trigeminal neuralgia patients, especially for patients who have not had a previous invasive treatment.

Trigeminal neuralgia: What are the important factors for good operative outcomes with microvascular decompression

BACKGROUND

Microvascular decompression has been widely used as the first choice in treating trigeminal neuralgia, but in a few patients, facial pain cannot be effectively controlled by microvascular decompression. We sought to clarify the important factors for good operative outcomes.

METHODS

We reviewed 62 patients with trigeminal neuralgia treated by microvascular decompression during the period 2000 through 2002, including clinical presentation, operative findings, techniques, and outcomes. Neurovascular conflicts were divided into single contact, contact and indentation, single adhesion, adhesion and indentation, and trigeminal nerve atrophy. Operative outcomes were graded into immediate postoperative complete pain relief (excellent), delayed postoperative complete pain relief (better), significant pain relief (good), and no response to microvascular decompression (poor).

RESULTS

All patients' presentations were typical at the time of pain onset, but the symptom in 17 patients changed to atypical before surgery. During operation, single contact and single adhesion was found in 14 patients and 15 patients, respectively; contact or adhesion in combination with indentation was found in 7 patients and 18 patients, respectively; atrophy occurred in 8 patients. Postoperatively, immediate and delayed complete pain relief was achieved in 32 (51.6%) patients and 17 (27.4%) patients, respectively; 11(17.7%) patients got significant pain relief; and 2 patients showed no response. The overall rate of complete pain relief in patients with shorter duration, typical presentation, artery compression and complete decompression was higher than that in patients with longer duration, atypical presentation, venous compression, and incomplete decompression.

CONCLUSIONS

Shorter duration, typical presentation, single artery compression, and complete decompression are the positive factors for better operative outcomes with microvascular decompression. Worse outcomes are usually related to venous compression, longer duration, and atypical presentation.

Management strategies for the treatment of neuropathic pain in the elderly

Pain caused by dysfunction or damage to the peripheral or central nervous system is typified by the symptoms described by patients with painful diabetic neuropathy, post-herpetic neuralgia and central poststroke pain. All these conditions are more common in the elderly. Neuropathic pain has long been recognised as one of the more difficult types of pain to treat; however, with the current emphasis on providing a multidisciplinary assessment and approach to management, more patients will be offered relief of their symptoms and an improved quality of life. Despite the use of combination drug therapy, adequate pain relief in the elderly is difficult to achieve without adverse effects. In an attempt to minimise these it is important to include non-drug treatment options in the management plan. Lifestyle changes and environmental modification, together with encouragement to adopt an appropriate exercise programme and an emphasis on maintaining mobility and independence should always be considered. Interventional therapy ranging from simple nerve blocks to intrathecal drug delivery can be of value. Drug treatment remains the mainstay of therapy. Tricyclic antidepressants such as amitriptyline, while having significant adverse effects in the elderly, have a number needed to treat (NNT) of 3.5 for 50% pain relief in diabetic neuropathy and 2.1 for 50% pain relief in postherpetic neuralgia. The newer antiepileptic drugs, such as gabapentin, appear to have a better adverse effect profile and provide similar efficacy with the NNT for treating painful diabetic neuropathy being 3.7 and 3.2 for treating pain in postherpetic neuralgia. As our understanding of the complexities of the pain processes increases, we are becoming more able to appropriately combine treatments to achieve not only improved pain relief but also improved function.