Microvascular Decompression for Trigeminal Neuralgia: Technical Refinement for Complication Avoidance

Multimodality Treatment of Trigeminal Neuralgia: An Institutional Experience

Object  Trigeminal neuralgia (TN) consists of excruciating paroxysmal pain, which lasts for seconds to minutes, in the distribution of fifth cranial nerve. TN is not life-threatening, but life became miserable because of high intensity of pain. This study aimed to assess the overall success rates of different treatments, considering pain relief, recurrence rates, and potential side effects. Material and Methods  A total of 203 patients of TN treated in the period of last 10 years, that is, 2013 to 2022, were included. Medial management was in 103, radiofrequency ablation in 17, neurectomy in 9, tumor excision in 6, and microvascular decompression (MVD) was done in 68 patients. Magnetic resonance imaging brain with fast imaging employing steady-state acquisition was the basic investigation to decide the etiology of disease. Results  Preliminary findings from our institutional experience indicate that a multidisciplinary approach, combining medical, surgical, and noninvasive treatments, yielded the most favorable results in managing TN. The majority of patients achieved significant pain reduction and improved quality of life with these selected therapies. However, certain subgroups of patients exhibited a higher propensity for treatment resistance, necessitating further investigation into personalized treatment strategies. Conclusion  Our study concludes that there is no definitive treatment modality (either medical or surgical) available for patients with TN. As the etiology of TN is varied, management of TN also varied, that is, multidisciplinary approach. Every type of treatment has pros and cons but when the cause of TN is vascular compression and patient's general condition permits for surgery, in such cases MVD should be preferred over the ablative procedures.

A novel 3D anatomical visualization system to avoid injuries of nerves in retrosigmoid approach

The retro-sigmoid approach (RA), widely used during different neurosurgical procedures, is burdened by the risk of injuries of the nerves that cross that region contributing to possible postoperative complications. By using, anatomage table (AT), a novel 3D anatomical visualization system, we described the nerves passing through the retromastoid area including the great occipital nerve (GON), the lesser occipital nerve (LON) and the great auricular nerve (GAN), and their courses from the origins, till terminal branches. Moreover, using dedicated software, we measured distances between the nerves and well-recognizable bony landmarks. After identifying the nerves and their distances from bony landmarks, we observed that the safest and risk-free skin incision should be made in an area delimited, superiorly from the superior nuchal line (or slightly higher), and inferiorly from a plane passing at 1-1.5 cm above the mastoid tip. The lateral aspect of such an area should not exceed 9.5-10 cm from the inion, while the medial one should be more than 7 cm far from the inion. This anatomical information has been useful in defining anatomical landmarks and reducing the risk of complications, mainly related to nerve injury, in RA. In-depth neuroanatomic knowledge of the cutaneous nerves of the retromastoid area is essential to minimize the complications related to their injury during different neurosurgical approaches. Our findings suggest that the AT is a reliable tool to enhance understanding of the anatomy, and thus contributing to the refinement of surgical techniques.

The outcomes of microvascular decompression for primary trigeminal neuralgia: insights from a single-center experience and technical advancements

Background

Microvascular decompression (MVD) remains the primary surgical treatment for trigeminal neuralgia due to its positive postoperative results. This study aims to evaluate the outcomes of patients with primary trigeminal neuralgia who underwent MVD. Additionally, the paper offers a detailed explanation of the surgical methodology of MVD employed at the neurosurgical hospital in Kazakhstan.

Methods

The study involved 165 medical records of patients with trigeminal neuralgia who underwent MVD between 2018 and 2020. Out of these 165 patients, 90 (54.55%) were included in the final analysis and were further evaluated using the Barrow Neurological Institute pain intensity score. Various variables were analyzed, including age, sex, affected side, dermatomes, offending vessel, and surgical intervention type. Moreover, the surgical technique employed at the hospital was described.

Results

The average follow-up period after the MVD procedure was 32.78 ± 9.91 months. The results indicated that out of the 90 patients, 80 (88.89%) achieved a good outcome as evidenced by BNI scores I and II. It was observed that patients with affected maxillary dermatomas and those with affected ophthalmic + maxillary dermatomas were more likely to experience fair + poor postsurgery BNI scores. On the other hand, patients with neurovascular conflicts involving the maxillary + mandibular dermatomas demonstrated good BNI scores (p = 0.01).

Conclusions

The outcomes of MVD in patients with primary trigeminal neuralgia showed good BNI scores within this study population. The outcome depended on the affected dermatome of the trigeminal nerve with the vessel. Additionally, patient positioning, intraoperative management including small skin incisions, minimal craniotomy, and precise closure of the dura, as well as intraoperative neurolysis, may contribute to achieving good clinical and satisfactory post-surgery aesthetic outcomes.

Microvascular decompression using autologous muscle graft for trigeminal neuralgia: a case series and meta-analysis

PURPOSE

We aimed to describe a case series of patients diagnosed with trigeminal neuralgia (TN) who were submitted to microvascular decompression (MVD) using autologous muscle graft (AMG) and perform a systematic review and meta-analysis.

METHODS

Forty-four adult patients who underwent MVD using AMG between 2012 and 2022 were studied retrospectively. Demographic, clinical, and surgical factors were assessed. We systematically reviewed PubMed, Embase, and Cochrane Library from inception to May 2023. We used random-effects model for all outcomes. Heterogeneity was assessed with I2. We used R software 4.3.1 for all statistical analyses.

RESULTS

Among patients in the case series, the mean age was 52 ± 12.9 years, and the proportion of females was 65.9%. Forty-one patients (93.2%) presented complete pain relief after a mean follow-up of 7.7 years. The pooled analysis of immediate pain relief was 91.3% (95% CI 82-96%; I2=78%). The good pain relief during follow-up was 88.2% (95% CI 78-94%; I2=80%) at follow-up. The recurrence rates at 6, 12, 36 months, and during follow-up were 6.2%, 10.5%, 10.3%, and 11%, respectively.

CONCLUSION

In this case series and meta-analysis of over 440 patients, our findings suggest that the practice of MVD using AMG may be an efficient option in the short term as surgical treatment for TN. Further trials should compare AMG with other materials and its effectiveness in a long-term follow-up.

Endoscopic microvascular decompression versus microscopic microvascular decompression for trigeminal neuralgia: A systematic review and meta-analysis

BACKGROUND

To compare the efficacy and safety of full endoscopic or endoscope-assisted microvascular decompression (E-MVD) and microscopic microvascular decompression (M-MVD) for primary trigeminal neuralgia (TN).

METHODS

We systematically searched the online database, including PubMed, Embase and Cochrane Library. The search terms used included, but were not limited to, "Trigeminal Neuralgia", "Microvascular Decompression Surgery" and "Endoscope". Postoperative facial pain relief and postoperative complications were considered for meta-analysis. All the outcomes were calculated as odds ratios (ORs) with 95% confidence intervals using R language.

RESULTS

A total of three studies involving 442 (E-MVD [218] versus M-MVD [224]) patients were included for analysis in our study. Postoperative facial pain relief (very much improved or much improved) was no difference between the two groups (OR, 0.95;95% CI, 0.57-1.58; I2 = 0%; p = 0.83). In addition, the occurrence of some postoperative complications was not statistically different between the two groups, including CSFleak (OR, 1.35;95% CI, 0.16-11.13; I2 = 0%; p = 0.94), facial paralysis (OR, 0.26;95% CI, 0.03-2.54; I2 = 0%; p = 0.67), hearing loss (OR, 0.87;95% CI, 0.30-2.55; I2 = 32%; p = 0.22), facial numbness (OR, 1.03;95% CI, 0.56-1.87; I2 = 62%; p = 0.10).

CONCLUSIONS

Both endoscopic microvascular decompression and microscopic microvascular decompression for trigeminal neuralgia appear to provide patients with equivalent facial pain relief outcomes. Complication rates were also similar between the groups.

Micro-Doppler for venous sinus localization in approaches to the cerebello-pontine angle

BACKGROUND

Main anatomical landmarks of retrosigmoid craniotomy are transverse sinus (TS), sigmoid sinus (SS), and the confluence of both. Anatomical references and guidance based on preoperative imaging studies are less reliable in the posterior fossa than in the supratentorial region. Simple intraoperative real-time guidance methods are in demand to increase safety.

METHODS

This manuscript describes the localization of TS, SS, and TS-SS junction by audio blood flow detection with a micro-Doppler system.

CONCLUSION

This is an additional technique to increase safety during craniotomy and dura opening, widening the surgical corridor to secure margins without carrying risks nor increase surgical time.

Preservation of Enlarged Mastoid Emissary Vein during Microvascular Decompression for Trigeminal Neuralgia Accompanied by Abnormal Venous Drainage: A Technical Case Report

During microvascular decompression (MVD) for trigeminal neuralgia (TGN), the mastoid emissary veins (MEV) are routinely sacrificed using the suboccipital retrosigmoid approach. The technical nuances when the MEV is an important collateral venous pathway for the obstructive internal jugular vein (IJV) have not been described thus far. Herein, we demonstrate for the first time a modified surgical technique for MVD to preserve the MEV. A 62-year-old man with a 10-year history of TGN refractory to carbamazepine was referred to our hospital for MVD. Preoperative imaging revealed that the superior cerebellar artery was the offending vessel. Computed tomography angiography also revealed that his contralateral IJV pathway was hypoplastic, and the ipsilateral pathway was severely stenosed by the external compression of the elongated styloid process and the transverse process of the first cervical vertebra. The ipsilateral MEV and the connecting occipital veins were enlarged as the sole collateral pathways of intracranial venous drainage. A modified MVD technique, including an upside-down L-shaped skin incision, layer-by-layer dissection of the occipital muscles, and denuding of the intraosseous part of the MEV, was used to cure the TGN with the preservation of the venous pathway. After surgery, the pain completely diminished without any complications. In conclusion, such technical modifications would be applicable in cases where the MEV needs to be preserved during posterior fossa surgery. Preoperative screening of the venous system is also recommended.

Factors Predicting Cerebrospinal Fluid Leaks in Microvascular Decompressions: A Case Series of 1011 Patients

BACKGROUND

Microvascular decompression (MVD) using a retrosigmoid approach is a highly effective, open-surgical procedure for neurovascular conflict in the posterior fossa, although there is a risk of postoperative cerebrospinal fluid (CSF) leak.

OBJECTIVE

To identify factors associated with postoperative CSF leakage after MVD.

METHODS

We retrospectively reviewed all patients who underwent MVDs at our institution from 2007 to 2020. Patient demographics, clinical diagnoses, and procedural characteristics were recorded and compared. Factors leading to CSF leak were analyzed using χ 2 , univariate, and multivariate regression.

RESULTS

Of 1011 patients who underwent MVDs, 37 (3.7%) presented with postoperative CSF leaks. In univariate analysis, the use of Cranios/Norian to obliterate the air cells was protective against CSF leak ( P = .01). Craniotomies ( P = .002), the use of dural substitutes such as Durepair ( P = .04), dural onlays such as DuraGen ( P = .04), muscle/fascia ( P = .03), and titanium mesh cranioplasty >5 cm ( P = .03) were associated with CSF leak. On multivariate analysis, only the presence of craniotomies ( P = .04) and nonprimary dural closure ( P = .03) were significant risk factors for CSF leak. When excluding the 34 (3.4%) patients who underwent a craniotomy, the lack of primary dural closure still remained significantly associated with postoperative CSF leak ( P = .04).

CONCLUSION

Our results represent one of the largest series of posterior fossa surgeries for a uniform indication in North America. Our study demonstrates increased risk for postoperative CSF leak when craniotomies are performed and when primary dural closure is not established. Given the small sample of patients who received a craniotomy, however, future studies corroborating this finding should be performed.

Correlation study between multiplanar reconstruction trigeminal nerve angulation and trigeminal neuralgia

OBJECTIVES

Neurovascular compression (NVC) produces morphological changes on the trigeminal nerve root is considered the cause of trigeminal neuralgia (TN), but there were some patients with TN found no NVC, and also NVC was found in asymptomatic individuals. Many studies found tight relationships of TN and morphological structures of trigeminal nerve. We designed this study to explore the correlation between multiplanar reconstruction (MPR) trigeminal nerve angulation (TNA) and TN.

METHODS

Patients with classical symptoms of TN were recruited as observation group (OG) in this study, 50 healthy controls were enrolled as control group (CG), the OG was further subtyped into young patients (YP), middle-aged patients (MP) and old patients (OP) based to the onset age of symptoms, and also divided into patients with or without trigger maneuvers (TM) based on the presence of TM or not. All the participants underwent magnetic resonance (MR) examinations in same device, bilateral TNA measurements were carried out in OG and CG, then TNA was compared between different groups or subgroups. All images were interpreted by two radiologists who were blinded to the study, diagnosis of TN was made by two senior neurosurgery professors.

RESULT

Ultimately, 95 patients with primary TN were recruited in OG, aged from 25 to 84 (61.15 ± 12.70) years with a course of 0.5 to 30 (5.03 ± 5.41) years, their onset age ranged from 24 to 82 (56.13 ± 11.98) years. There were 34 males and 61 females in OG, and 58 cases involved right side. The CG aged from 22 to 85 (61.86 ± 13.03) years. No statistical difference was found between the age of OG and CG(p = 0.76), and also the bilateral TNA of CG (154.92 ± 16.90° vs 155.55 ± 17.03°, p > 0.05), while TNA of OG was significantly smaller than CG (150.78 ± 11.29° vs 155.24 ± 16.88°, p = 0.019). In OG, TNA on the affected side was significantly smaller than the unaffected side (149.29 ± 12.44° vs 152.27 ± 9.85°, p = 0.014). TNA showed a positive correlation with onset age of patients with TN, as TNA on the affected side of YP was significantly smaller than MP and OP (139.00 ± 11.64° vs 148.86 ± 11.54°, 139.00 ± 11.64° vs 152.18 ± 12.61°, p = 0.004 and 0.026). Furthermore, patients with TM showed smaller TNA than those without TM (147.05 ± 11.30° vs 164.75 ± 8.39°, p < 0.001).

CONCLUSIONS

This study suggested that TNA might play a role in TN, small TNA could be a risk factor of TN. Furthermore, patients with small TNA are more likely to combine with TM, but more studies are needed to explore the exact role of TNA in TN.

A Laboratory Investigation on a Tailored Skin and Muscle Flap Variant for the Retrosigmoid Approach

Introduction An anatomical study was conducted to test a modified C-shaped flap designed for patients undergoing a keyhole approach and/or minicraniotomy for retrosigmoid approach (KRSA).

Materials and Methods Ten heads specimens were used. The surgical technique investigated was based on a 4-cm C-shaped skin incision with medial convexity (placed 8 cm laterally to the external occipital protuberance, with the lower edge terminating 1.5 to 2 cm above the mastoid tip), which followed by careful subperiosteal dissection and completed by reflecting and securing the skin flap layer anteriorly and the muscle flaps superiorly and inferiorly by stitches. Anatomical findings, including depth of surgical corridor till to the cerebellopontine cistern (CPC) as well as the sparing of neurovascular structures, were evaluated in every specimen.

Results Twenty surgical approaches to CPC were conducted, resulting in a short working distance to the target (32 mm) without any need for a self-retaining retractor. In every specimen, the integrity of occipital muscles and cutaneous nerves was maintained, and a solid multilayer closure was always achieved. These data suggest that landmarks-based design of this C-shaped incision could be helpful in avoiding damages to the soft tissues encountered during KRSA.

Conclusion This modified approach provides a wide surgical corridor to access the CPC while ensuring the minimal invasiveness of the standard S-shaped incision. Compared with the latter, it preserves better the integrity of the surrounding soft tissues and appears less likely to cause any iatrogenic injury to occipital muscles and cutaneous nerves.

Global Trends and Hotspots in Trigeminal Neuralgia Research From 2001 to 2021: A Bibliometric Analysis

Background

In recent years, there have been an increasing number of studies on trigeminal neuralgia (TN). However, a scientific and comprehensive study of the current situation and trends in the field of TN research is lacking. The purpose of this study is to summarize and visualize the development, research hotspots, and future trends in TN based on a bibliometric approach.

Methods

Studies on TN published from 2001 to 2021 were obtained from the Web of Science Core Collection (WoSCC). Bibliometrics, CiteSpace, and VOSviewer tools were used for bibliometric analysis and visualization.

Results

In total, 4,112 documents were searched. The number of research articles in the field is generally on an upward trend, with the fastest growth in the number of articles from 2017 to 2020. Shanghai Jiao Tong University, Pittsburgh University, and Mayo Clinic are the three institutions with the most publications. Shiting Li and Zakrzewska JM are the most prolific author and top co-cited authors, respectively. The Journal of Neurosurgery is the most influential journal. The top 5 keywords in that time frame are TN, microvascular decompression, facial pain, stereotactic radiosurgery, and neuropathic pain.

Conclusion

This is the first comprehensive scientific bibliometric analysis of the global research field on TN over the past 21 years, providing a meaningful reference for further exploration of topical issues and research trends in the field.

Surgical treatment for Trigeminal neuralgia

Various treatments for trigeminal neuralgia (TN) are known to yield initial satisfactory results; however, the surgical treatment has excellent long-term outcomes and a low recurrence rate. Surgical treatment addresses the challenge of vascular compression, which accounts for 85% of the causes of TN. As for surgical treatment for TN, microvascular decompression (MVD) has become the surgical treatment of choice after Peter J. Jannetta reported the results of MVD surgery in 1996. Since then, many studies have reported a success rate of over 90% for the initial surgical treatment. Most MVDs aim to separate (decompress) the culprit vessel from the trigeminal nerve. To increase the success rate of surgery, accurate indications for MVD and management of the offender vessels without complications are critical. In addition, if there is no vascular compression, partial sensory rhizotomy or internal neurolysis can be performed to improve surgical outcomes.

Trigeminal Neuralgia: Current Approaches and Emerging Interventions

Trigeminal neuralgia (TN) has been described in the literature as one of the most debilitating presentations of orofacial pain. This review summarizes over 150 years of collective clinical experience in the medical and surgical treatment of TN. Fundamentally, TN remains a clinical diagnosis that must be distinguished from other types of trigeminal neuropathic pain and/or facial pain associated with other neuralgias or headache syndromes. What is increasingly clear is that there is no catch-all medical or surgical intervention that is effective for all patients with trigeminal neuralgia, likely reflective of the fact that TN is likely a heterogenous group of disorders that jointly manifests in facial pain. The first-line treatment for TN remains anticonvulsant medical therapy. Patients who fail this have a range of surgical options available to them. In general, microvascular decompression is a safe and effective procedure with immediate and durable outcomes. Patients who are unable to tolerate general anesthesia or whose medical comorbidities preclude a suboccipital craniectomy may benefit from percutaneous methodologies including glycerol or radiofrequency ablation, or both. For patients with bleeding diathesis due to blood thinning medications who are ineligible for invasive procedures, or for those who are unwilling to undergo open surgical procedures, radiosurgery may be an excellent option-provided the patient understands that maximum pain relief will take on the order of months to achieve. Finally, peripheral neurectomies continue to provide an inexpensive and resource-sparing alternative to pain relief for patients in locations with limited economic and medical resources. Ultimately, elucidation of the molecular mechanisms underlying trigeminal neuralgia will pave the way for novel, more effective and less invasive therapies.

[Diagnostics and therapy of neuropathic pain]

Neuropathic pain is pain caused by a lesion or disease of the somatosensory nervous system. Scientific studies have shown that neuropathic pain is the result of complex altered signalling processes in the peripheral and central nervous system. Current forms of treatment of neuropathic pain are causally oriented but also aim at symptomatic analgesia by pharmacological and nonpharmacological methods. Furthermore, psychological pain management techniques are used in a supportive role. This review summarizes the contemporary diagnostics of neuropathic pain using frequent diseases as examples and presents the evidence from randomized controlled trials on the treatment of neuropathic pain. Treatment guidelines for pharmacological management of neuropathic pain include evidence-based use of antidepressants, anticonvulsants, opioids, capsaicin and lidocaine.

Impact of C-shaped skin incision on surgical operability in the retrosigmoid approach: when a good start is half of the job

BACKGROUND

The retrosigmoid approach (RSA) is one of the routes of choice to approach tumors and vascular lesions of the cerebellopontine angle. Among different types of skin incisions and soft tissue dissection techniques, the most widely used variants comprise the straight/lazy S-shaped and the C-shaped incisions. Several reports discuss advantages in terms of functional and clinical outcomes of the C-shaped incision, but scientific considerations about the critical impact of this kind of incision on surgical operability are still extremely limited.

OBJECT

Authors comparatively analyze the advantage provided by C-shaped incision in RSA in terms of anatomic exposure and surgical operability, compared with straight/lazy S-shaped one.

METHODS

A comparative microanatomical laboratory investigation was conducted. The operability score (OS) was applied for quantitative analysis of surgical operability.

RESULTS

C-shaped incision, providing a significant reduction of the overall working distance (-13%) together with an overall increase of the maneuverability area (+ 204.9%), did improve the conizing effect on the surgical corridor. It optimized overall maneuverability of surgical instruments, in terms of angle of attack (+ 27.7%), as well as maneuverability arc (+ 122%), on the entire surgical field. C-shaped incision ensured good operability on all surgical targets (OS ranging from 2 to 3), most significantly improving surgical maneuverability at the porus trigeminus and internal acoustic meatus.

CONCLUSION

C-shaped incision in the RSA significantly improves anatomic exposure and surgical operability as compared with straight/lazy S-shaped incision.

A Novel Technical Refinement of Microvascular Decompression: Pain Relief and Complication Rate in a Consecutive Series of Patients With Trigeminal Neuralgia

BACKGROUND

Microvascular decompression (MVD) represents a milestone for the treatment of trigeminal neuralgia (TN). Nevertheless, several complications still occur and may negatively affect the outcome. We recently proposed some technical nuances for complication avoidance related to MVD.

OBJECTIVE

To verify the efficacy of the proposed refinement of the standard MVD technique in terms of resolution of the pain and reduction of complication rates.

METHODS

We analyzed surgical and outcome data of patients with TN using a novel surgical refinement to MVD, over the last 4 yr. Outcome variables included pain relief, facial numbness, muscular atrophy, local cutaneous occipital and temporal pain or numbness, cerebellar injury, hearing loss, cranial nerve deficits, wound infection, and cerebrospinal fluid (CSF) leak. Overall complication rate was defined as the occurrence of any of the aforementioned items.

RESULTS

A total of 72 consecutive patients were enrolled in the study. Pain relief was achieved in 91.6% and 88.8% of patients at 1- and 4-yr follow-up, respectively. No patient reported postoperative facial numbness during the entire follow-up period. The incidence of CSF leak was 1.4%. One patient developed a complete hearing loss and another a minor cerebellar ischemia. There was no mortality. The overall complication rate was 5.6%, but only 1.4% of patients experienced permanent sequelae.

CONCLUSION

The proposed refinement of the standard MVD technique has proved effective in maintaining excellent results in terms of pain relief while minimizing the overall complication rate associated with this surgical approach.

Structural and functional biomarkers of efficacy of navigated repetitive transcranial magnetic stimulation in therapy for trigeminal neuralgia

Repetitive transcranial magnetic stimulation (rTMS) is an alternative treatment option for patients with drug-resistant trigeminal neuralgia (TN). However, the effect of rTMS is variable. The aim of this study was to find neuroimaging biomarkers of clinical efficacy of navigated rTMS. Seventeen patients with TN (14 women and 3 men, median age 56 years) received 10 sessions of high-frequency rTMS of the motor cortex contralateral to pain side. The data were analyzed for correlations between functional connectivity (FC), the grey matter (GM) volume and the reduction in pain intensity. Positive correlations were established between the reduction in average pain intensity and GM volume in caudate nuclei in both hemispheres (p(unc) = 0.03), both cerebellar hemispheres (p(unc) = 0.002) and the postcentral gyrus contralateral to pain side (p(unc) = 0.005); between the reduction in peak pain intensity and GM volume in the caudate nucleus contralateral to pain side (p(unc) = 0.04) and the cerebellar hemisphere ipsilateral to pain (p(unc) = 0.03). Significant positive correlations were discovered between the reduction in average pain intensity and FC between the thalamus contralateral to pain side, the postcentral gyrus and the insular operculum (both ipsilateral to pain side; (p(FWE) = 0.018), as well as between the cingulate cortex and the anterior cingulate cortex ipsilateral to pain (p(FWE) = 0.017), between the contralateral subcallosal gyrus and the cerebellar hemisphere ipsilateral to pain (p(FWE) = 0.018). A negative correlation was established for FC between the contralateral putamen and the occipital lobes in both hemispheres (p(FWE) = 0.001). Our findings may spur the development of individual predictors of rTMS efficacy in patients with chronic pain.

Microvascular decompression for typical trigeminal neuralgia: Personal experience with intraoperative neuromonitoring with level-specific-CE-Chirp® brainstem auditory evoked potentials in preventing possible hearing loss

Background:

Permanent hearing loss after posterior fossa microvascular decompression (MVD) for typical trigeminal neuralgia (TTN) is one of the possible complications of this procedure. Intraoperative brainstem auditory evoked potentials (BAEPs) are used for monitoring the function of cochlear nerve during cerebellopontine angle (CPA) microsurgery. Level-specific (LS)-CE-Chirp® BAEPs are the most recent evolution of classical click BAEP, performed both in clinical studies and during intraoperative neuromonitoring (IONM) of acoustic pathways during several neurosurgical procedures.

Methods:

Since February 2016, we routinely use LS-CE-Chirp® BAEPs for monitoring the function of cochlear nerve during CPA surgery, including MVD for trigeminal neuralgia. From September 2011 to December 2018, 71 MVDs for TTN were performed in our department, 47 without IONM of acoustic pathways (Group A), and, from February 2016, 24 with LS-CE-Chirp BAEP (Group B).

Results:

Two patients of Group A developed a permanent ipsilateral anacusia after MVD. In Group B, we did not observe any permanent acoustic deficit after surgery. In one case of Group B, during arachnoid dissection, intraoperative LS-CE-Chirp BAEP showed a temporary lag of V wave, resolved in 5 min after application of intracisternal diluted papaverine (0.3% solution without excipients).

Conclusion:

MVD is widely considered a definitive surgical procedure in the management of TTN. Even though posterior fossa MVD is a safe procedure, serious complications might occur. In particular, the use of IONM of acoustic pathways during MVD for TTN might contribute to prevention of postoperative hearing loss.

Factors affecting outcome in frameless non-isocentric stereotactic radiosurgery for trigeminal neuralgia: a multicentric cohort study

BACKGROUND

Stereotactic radiosurgery (SRS) is an effective treatment for trigeminal neuralgia (TN). Nevertheless, a proportion of patients will experience recurrence and treatment-related sensory disturbances. In order to evaluate the predictors of efficacy and safety of image-guided non-isocentric radiosurgery, we analyzed the impact of trigeminal nerve volume and the nerve dose/volume relationship, together with relevant clinical characteristics.

METHODS

Two-hundred and ninety-six procedures were performed on 262 patients at three centers. In 17 patients the TN was secondary to multiple sclerosis (MS). Trigeminal pain and sensory disturbances were classified according to the Barrow Neurological Institute (BNI) scale. Pain-free-intervals were investigated using Kaplan Meier analyses. Univariate and multivariate Cox regression analyses were performed to identify predictors.

RESULTS

The median follow-up period was 38 months, median maximal dose 72.4 Gy, median target nerve volume 25 mm³, and median prescription dose 60 Gy. Pain control rate (BNI I-III) at 6, 12, 24, 36, 48, and 60 months were 96.8, 90.9, 84.2, 81.4, 74.2, and 71.2%, respectively. Overall, 18% of patients developed sensory disturbances. Patients with volume ≥ 30 mm³ were more likely to maintain pain relief (p = 0.031), and low integral dose (< 1.4 mJ) tended to be associated with more pain recurrence than intermediate (1.4-2.7 mJ) or high integral dose (> 2.7 mJ; low vs. intermediate: log-rank test, χ² = 5.02, p = 0.019; low vs. high: log-rank test, χ² = 6.026, p = 0.014). MS, integral dose, and mean dose were the factors associated with pain recurrence, while re-irradiation and MS were predictors for sensory disturbance in the multivariate analysis.

CONCLUSIONS

The dose to nerve volume ratio is predictive of pain recurrence in TN, and re-irradiation has a major impact on the development of sensory disturbances after non-isocentric SRS. Interestingly, the integral dose may differ significantly in treatments using apparently similar dose and volume constraints.

Endoscopic versus open microvascular decompression for trigeminal neuralgia: a systematic review and comparative meta-analysis

OBJECTIVE

Microvascular decompression (MVD) is commonly used in the treatment of trigeminal neuralgia (TN) with positive clinical outcomes. Fully endoscopic MVD (E-MVD) has been proposed as an effective minimally invasive alternative, but a comparative review of the two approaches has not been conducted. The authors performed a meta-analysis of studies, comparing patient outcome rates and complications for the open versus the endoscopic technique.

METHODS

The PubMed/MEDLINE and Ovid databases were searched for studies published from database inception to 2017. The search terms used included, but were not limited to, "open microvascular decompression," "microvascular decompression for trigeminal neuralgia," and "endoscopic decompression for trigeminal neuralgia." Criteria for inclusion of studies in the meta-analysis were established as follows: adult patients, clinical studies with ≥ 10 patients (excluding case studies to obtain a higher volume of outcome rates), utilization of open MVD or E-MVD to treat TN, craniotomy and retrosigmoid incision, English-language studies, and articles that listed pain relief outcomes (complete, very good, partial, or absent), recurrence rate (number of patients), and complications (paresis, hearing loss, CSF leakage, cerebellar damage, infection, death). Relevant references from the chosen articles were also included.

RESULTS

From a larger pool of 1039 studies, 23 articles were selected for review: 13 on traditional MVD and 10 on E-MVD. The total number of patients was 6749, of which 5783 patients (and 5802 procedures) had undergone MVD and 993 patients (and procedures) had undergone E-MVD. Analyzed data included postoperative pain relief outcome (complete or good pain relief vs partial or no pain relief), and rates of recurrence and complications including facial paralysis, weakness, or paresis; hearing loss; auditory and facial nerve damage; cerebrospinal fluid leakage; infection; cerebellar damage; and death.Good pain relief was achieved in 81% of MVD patients and 88% of E-MVD patients, with a mean recurrence rate of 14% and 9%, respectively. Average rates of reported complications were statistically lower in E-MVD than in MVD approaches, including facial paresis or weakness, hearing loss, cerebellar damage, infection, and death, whereas cerebrospinal fluid leakage was similar. The overall incidence of complications was 19% for MVD and 8% for E-MVD.

CONCLUSIONS

The reviewed literature revealed similar clinical outcomes with respect to pain relief for MVD and E-MVD. The recurrence rate was lower in E-MVD studies, though not significantly so, and the incidence of complications, notably facial paresis and hearing loss, were statistically higher for MVD than for E-MVD. Based on these results, the use of endoscopy to perform MVD for TN appears to offer at least as good a surgical outcome as the more commonly used open MVD, with the possible added advantages of having a shorter operative time, smaller craniotomy, and lower recurrence rates. The authors advise caution in interpreting these data given the asymmetry in the sample size between the two groups and the relative novelty of the E-MVD approach.