Reoperation for recurrent trigeminal neuralgia after microvascular decompression

Repeat Surgery for Recurrent or Refractory Trigeminal Neuralgia: A Systematic Review and Meta-Analysis

OBJECTIVE

Surgery can effectively treat Trigeminal neuralgia (TN), but postoperative pain recurrence or nonresponse are common. Repeat surgery is frequently offered but limited data exist to guide the selection of salvage surgical procedures. We aimed to compare pain relief outcomes after repeat microvascular decompression (MVD), percutaneous rhizotomy (PR), or stereotactic radiosurgery (SRS) to determine which modality was most efficacious for surgically refractory TN.

METHODS

A PRISMA systematic review and meta-analysis was performed, including studies of adults with classical or idiopathic TN undergoing repeat surgery. Primary outcomes included complete (CPR) and adequate (APR) pain relief at last follow-up, analyzed in a multivariate mixed-effect meta-regression of proportions. Secondary outcomes were initial pain relief and facial numbness.

RESULTS

Of 1299 records screened, 61 studies with 68 treatment arms (29 MVD, 14 PR, and 25 SRS) comprising 2165 patients were included. Combining MVD, PR, and SRS study data, 68.8% achieved initial CPR after a repeat TN procedure. On average, 49.6% of the combined sample of MVD, PR, and SRS had CPR at final follow-up, which was on average 2.99 years postoperatively. The proportion (with 95% CI) achieving CPR at final follow-up was 0.57 (0.51-0.62) for MVD, 0.60 (0.52-0.68) for PR, and 0.35 (0.30-0.41) for SRS, with a significantly lower proportion of pain relief with SRS. Estimates of initial CPR for MVD were 0.82 (0.78-0.85), 0.68 for PR (0.6-0.76), and 0.41 for SRS (0.35-0.48).

CONCLUSIONS

Across MVD, PR, and SRS, about half of TN patients maintain complete CPR at an average follow-up time of 3 years after repeat surgery. In treating refractory or recurrent TN, MVD and PR were superior to SRS in both initial pain relief and long-term pain relief at final follow-up. These findings can inform surgical decision-making in this challenging population.

CyberKnife Radiosurgery for refractory bilateral trigeminal neuralgia. Case report

Case description: A case of a 37-year-old female patient suffering from refractory bilateral trigeminal neuralgia is presented, who underwent various interventions such as acupuncture, block therapies and even microvascular decompression without effective pain relief.

Clinical findings

Paresthesias and shooting-like twinges of pain intensity 10/10 in bilateral maxillary and mandibular branches of the trigeminal nerve, with nasal and intraoral triggers that made eating impossible, becoming increasingly severe since refractoriness to microvascular decompression and carbamazepines, triggering the twinges even during sleep, generating somnolence, depressive mood and social isolation.

Treatment and results

The patient was evaluated by an interdisciplinary neuro-oncology team, where, in accordance with the analysis of the brain magnetic resonance imaging and the patient's history, it was indicated to perform Cyberknife® radiosurgery in monofraction on the left trigeminal and subsequently treat the contralateral trigeminal. When treated with Cyberknife® radiosurgery, the patient reported absolute improvement in her pain for 2 years.

Clinical relevance

Radiosurgery by CyberKnife is not yet the first line of management in trigeminal neuralgia, however, it should be considered since several studies have managed to demonstrate an increase in the quality of life of patients and pain relief in refractory or severe cases. of said pathology.

A Systematic Review of Repeat Microvascular Decompression for Recurrent or Persistent Trigeminal Neuralgia

OBJECTIVE

When conservative therapy fails, microvascular decompression (MVD) has been the preferred treatment of primary trigeminal neuralgia (TN). However, the management of recurrent or persistent TN after MVD can often be difficult. The purpose of the present systematic review was to objectively analyze and summarize the reported literature regarding the feasibility of repeat MVD.

METHODS

We conducted a database search using the MEDLINE and PubMed databases until July 2020. The search terms used for title and abstract screening were as follows: "recurrent trigeminal neuralgia," "persistent trigeminal neuralgia," "repeat microvascular decompression," and "reexploration." The inclusion criteria for the systematic review were as follows: clinical studies (excluding case studies), repeat MVD treatment of TN, and studies that had recorded the pain relief outcomes, operative findings, and complications (if any).

RESULTS

Of the 1771 initial results obtained, we performed a full text screening of 43 studies, and, ultimately, 19 were deemed eligible. A total of 2247 patients had undergone MVD for TN, of whom, 311 had experienced recurrence (13.84%). Of the 311 patients, 178 had undergone repeat MVD. The average pain-free interval was 27.75 months after the first MVD. The effective rate of repeat MVD was 91.66%, and 71.48% of the patients had had obvious compression found at repeat MVD. The postoperative complication rate after repeat MVD was 37.31% and was due to postoperative adhesions around the nerve and nerve injury caused by partial sensory rhizotomy. The most common complication after repeat MVD was facial numbness (21.89%), although the incidence of other complications was <5%.

CONCLUSIONS

For patients with recurrent or persistent pain after MVD, the findings from our systematic review support that repeat MVD remains a feasible treatment for recurrent or persistent TN.

Microvascular Transposition Without Teflon: A Single Institution's 17-Year Experience Treating Trigeminal Neuralgia

BACKGROUND

Trigeminal neuralgia (TN) refractory to medical management is often treated with microvascular decompression (MVD) involving the intracranial placement of Teflon. The placement of Teflon is an effective treatment, but does apply distributed pressure to the nerve and has been associated with pain recurrence.

OBJECTIVE

To report the rate of postoperative pain recurrence in TN patients who underwent MVD surgery using a transposition technique with fibrin glue without Teflon.

METHODS

Patients were eligible for our study if they were diagnosed with TN, did not have multiple sclerosis, and had an offending vessel that was identified and transposed with fibrin glue at our institution. All eligible patients were given a follow-up survey. We used a Kaplan-Meier (KM) model to estimate overall pain recurrence.

RESULTS

A total of 102 patients met inclusion criteria, of which 85 (83%) responded to our survey. Overall, 76 (89.4%) participants responded as having no pain recurrence. Approximately 1-yr pain-free KM estimates were 94.1% (n = 83), 5-yr pain-free KM estimates were 94.1% (n = 53), and 10-yr pain-free KM estimates were 83.0% (n = 23).

CONCLUSION

Treatment for TN with an MVD transposition technique using fibrin glue may avoid some cases of pain recurrence. The percentage of patients in our cohort who remained pain free at a maximum of 17 yr follow-up is on the high end of pain-free rates reported by MVD studies using Teflon. These results indicate that a transposition technique that emphasizes removing any compression near the trigeminal nerve root provides long-term pain-free rates for patients with TN.

Teflon versus Ivalon in Microvascular Decompression for Trigeminal Neuralgia: A 2-Center 10-Year Comparison

BACKGROUND

Trigeminal neuralgia features jolts of pain along the distribution of the trigeminal nerve. If patients fail conservative management, microvascular decompression (MVD) is typically the next step in treatment. MVD consists of implanting a separating material, often Teflon, between the nerve and compressive lesions. A review found similar success and complication rates between Teflon and Ivalon, another commonly used material. The aim of this study was to analyze outcomes and complications associated with Teflon and Ivalon in MVD.

METHODS

We conducted a 2-center retrospective cohort study of trigeminal neuralgia treated with MVD between 2005 and 2019. Patients with no postoperative follow-up were excluded. Postoperative pain was graded using the Barrow Neurological Institute (BNI) pain intensity score. Relapse was defined as a BNI score of 4-5 during follow-up after initial pain improvement or an initial BNI score of 1-3.

RESULTS

The study included 221 MVD procedures in 219 patients. Ivalon was implanted in 121 procedures, and Teflon was implanted in 100 procedures. Multivariate analysis found that implant type had no effect on final BNI score (P = 0.305). Relapse rates were similar at 5- and 10-year follow-up (5-year: Ivalon 10.7%, Teflon 18.0%, P = 0.112; 10-year: Ivalon 11.6%, Teflon 19.0%, P = 0.123). There was no difference in postoperative immediate facial numbness (P = 0.125). Postoperative hearing difficulty was higher in the Ivalon cohort (8.4% vs. 1.0%; P = 0.016).

CONCLUSIONS

We found no significant difference in final BNI score or risk of relapse between Ivalon and Teflon. Complications were similar, although Ivalon was more associated with temporary postoperative hearing loss.

On the Surgical Implications of Peritrigeminal Perforating Vessels in Microvascular Decompression

BACKGROUND

Perforating branches arising from the superior cerebellar artery (SCA) or anterior inferior cerebellar artery (AICA) that pierces the brainstem within 5 mm of the trigeminal root may limit offending vessel transposition during microvascular decompression for trigeminal neuralgia.

OBJECTIVE

To investigate the microsurgical anatomy of peritrigeminal perforators and evaluate their effect on the mobility of the SCA and AICA. Additionally, we propose strategies for mitigating the potential complications caused by the presence of short peritrigeminal perforators.

METHODS

Retrosigmoid approaches and exposure of the upper cerebellopontine angle were performed on 11 cadaveric heads (22 sides). The number, origin, and course of perforators were recorded and each was classified as either type I, short straight (<3 mm); type II, long straight perforators (>3 mm); or type III, long circumflex (>3 mm). Transposition of each SCA and AICA away from trigeminal nerve was performed, and degree of mobilization was evaluated and graded.

RESULTS

A total of 123 perforators were identified, of which 44 were considered peritrigeminal. Of these, 19 arose from the AICA, 18 from the SCA, and 7 from the basilar artery. Type I peritrigeminal perforators were the most common at 77.3%. Transposition or interposition of the parent vessel was not possible in 8 (47.1%) instances.

CONCLUSION

Identification of inhibiting perforators is essential before performing microvascular decompression to avoid ischemic injury to the brainstem. The presence of type I perforators may necessitate extensive arachnoid dissection and use of an interpositioning technique with minimal repositioning of the offending vessel.

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.

Reappearance of Cranial Nerve Dysfunction Symptoms Caused by New Artery Compression More than 20 Years after Initially Successful Microvascular Decompression: Report of Two Cases

Reappearance of symptoms of cranial nerve dysfunction is not uncommon after successful microvascular decompression (MVD). The purpose of this study was to report two quite unusual cases of recurrent and newly developed hemifacial spasm (HFS) caused by a new conflicting artery more than 20 years after the first successful surgery. In Case 1, the first MVD was performed for HFS caused by the posterior inferior cerebellar artery (PICA) when the patient was 38 years old. After 26 symptom-free years, HFS recurred on the same side of the face due to compression by the newly developed offending AICA. In Case 2, the patient was first operated on for trigeminal neuralgia by transposition of the AICA at 49 years old, but 20 symptom-free years after the first MVD, a new offending PICA compressed the facial nerve on the same side, causing HFS. These two patients underwent reoperation and gained satisfactory results postoperatively. Reappearance of symptoms related to compression of the root exit zone (REZ) by a new offending artery after such a long symptom-free interval since the first effective MVD is rare. Here, we describe two such unusual cases and discuss how to manage and prevent such reappearance of symptoms after a long time interval.

[Microvascular decompresion for trigeminal neuralgia, report of 36 cases and literature review]

Objetivo:

El propósito del presente trabajo es presentar los resultados de 36 pacientes con diagnóstico de neuralgia del trigémino (NT), en los cuales se realizó una descompresión microvascular (DMV).

Material y Método:

Desde junio de 2005 a mayo de 2012, 36 pacientes con diagnóstico de NT fueron operados por el primer autor (AC), realizando una DMV. Se evaluó: Edad, sexo, tiempo de sintomatología previo a la cirugía, hallazgos intraoperatorios (a través de los videos quirúrgicos), y resultados postoperatorios.

Resultados:

De los 36 pacientes operados, 25 fueron mujeres y 11 varones. El promedio de edad fue de 48 años. El seguimiento postoperatorio fue en promedio de 38 meses. De los 36 pacientes, 32 (88%) evolucionaron sin dolor hasta la fecha. De los 4 casos con recurrencia de dolor, en dos pacientes se observó como hallazgo intraoperatorio un conflicto venoso.

Conclusión:

La DMV como tratamiento de la NT es un procedimiento efectivo y seguro. El hallazgo intraoperatorio de una “compresión” venosa podría indicar una evolución postoperatoria desfavorable.

Microvascular decompression for trigeminal neuralgia using the 'Stitched Sling Retraction' technique in recurrent cases after previous microvascular decompression

BACKGROUND

Microvascular decompression is a well-known therapeutic option for trigeminal neuralgia. It is considered safe and effective, and is the surgical treatment of choice for the malady. However, there is no standard technique for it and different authors have proposed different techniques of performing it. In this study, we observe the clinical results of the so-called 'stitched sling retraction' technique for recurrent cases of trigeminal neuralgia.

METHODS

Twelve consecutive patients with recurrent trigeminal neuralgia after previous microvascular decompression(s) were admitted to our institution form February 2009 to February 2011 and underwent microvascular decompression of the trigeminal nerve using the 'stitched sling retraction' technique. In this technique, the offending loop of the superior cerebellar artery is retracted from the nerve and, using a silk thread loop around it, is suspended to the adjacent tentorium.

RESULTS

All patients experienced pain resolution during the immediate post-operative period or within the first 6 months after surgery. They were followed for 24 to 38 months. No recurrence occurred.

CONCLUSIONS

The 'stitched sling retraction' technique shows promising preliminary results in recurrent cases of trigeminal neuralgia after previous microvascular decompression(s). Since it is a 'transposing' technique, it might be associated with less recurrence rates (due to resuming of the neurovascular conflict) than the classic interposing technique, which uses a prosthesis between the offending vessel and the trigeminal nerve.

Trigeminal neuralgia occurs and recurs in the absence of neurovascular compression

Object

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.

Recurrent trigeminal neuralgia at 20 years after surgery: case report

Microvascular decompression (MVD) is now the most feasible method of treatment for trigeminal neuralgia (TN). The recurrence of symptoms is rarely encountered postoperatively. A female patient with typical right V3 distribution TN had been successfully treated by MVD at age 56 years by transposing the offending superior cerebellar artery, and she became completely pain-free postoperatively without sequelae. Twenty years after the first MVD, pain recurred on the right V2 distribution at age 76 years and she was operated on a second time to resolve the pain. Re-exploration surgery revealed that the trigeminal nerve was compressed mediocranially by the anterior inferior and posterior inferior cerebellar artery complex, which had not been close to the neural structure during the first surgery. The artery complex was successfully transpositioned to decompress the root exit zone (REZ) of the nerve and she became pain-free again. Although various causal factors likely contribute to recurrence of TN, the present case of recompression of a REZ occurred due to a newly developed offending artery which caused TN a long time after the first surgery.

Outcome of microvascular decompression for trigeminal neuralgia using autologous muscle graft: A five-year prospective study

Introduction:

Trigeminal Neuralgia (TGN) is a syndrome characterized by Paroxysmal, shock like hemifacial pain. Among the various treatment options micro vascular decompression (MVD) has gained popularity in the recent years.

Materials and Methods:

182 patients underwent MVD, between 1995–2007 out of 530 patients treated for Trigeminal Neuralgia at our service. All were operated by retro auricular sub occipital craniectomy by a single surgeon using autologous muscle graft. They were assessed for pain relief, complications and the data was analysed.

Results:

Males were 84 (61.3%) females 53 (38%) with a ratio of 1.5=1. Age ranged from 25-75 years. Duration of symptoms ranging from 6 months to 25 years (average 4-6 years). Seventy seven (56.2% were affected on the right side whereas 60 (43.8%) had pain on the left side. Imaging demonstrated vascular compression in 84 (61%). At surgery superior cerebellar artery was the commonest cause of compression in 71.5%. More than one artery was found in relation to the nerve in 15.3%. There was no mortality, CSF leak 2.9% and transient facial palsy in 2.2% were the notable complications.

Conclusion:

MVD is the procedure of choice for TGN if there is no contraindication for surgery. Adequate tissue respect, meticulous surgical steps and experience will reduce complications. Autologus muscle graft can give comparable and durable results possibly with lesser complications.

"Double-stick tape" technique for transposition of an offending vessel in microvascular decompression: technical case report

BACKGROUND AND IMPORTANCE

Severe hemifacial spasm caused by compression by a tortuous vertebral artery (VA) often is encountered and is difficult to treat. We describe a patient with hemifacial spasm caused by compression of the facial nerve by a tortuous VA. A simple and effective transposition approach, a "double-stick tape" technique, to the offending artery using a fibrin tissue-adhesive collagen fleece product (TachoComb) is reported.

CLINICAL PRESENTATION

A 65-year-old woman presented with an 8-year history of right-sided facial spasms, including the orbicularis oculi and orbicularis oris muscles. MRI revealed a tortuous right VA indented into the pontomedullary junction. The right anterior inferior cerebellar artery (AICA) also contacted the proximal portion of the facial nerve. Surgical exploration with standard retrosigmoid craniotomy was performed. The offending VA was dissected away from the pontomedullary junction toward the cranial base. A small piece of TachoComb, with fibrin glue applied on the non-coated side of the fleece to make a "double-stick tape," was then placed on the ventral surface of the VA. Until the glue hardened, the VA was held away from the brainstem onto the dura of the petrous pyramid. After this procedure, AICA transposition was performed. The patient's symptoms were completely resolved immediately after surgery, and she remained asymptomatic at her 1 year follow-up visit.

CONCLUSION

The advantage of our "double-stick tape" technique is the simplicity of the procedure. The present technique is a feasible alternative for the treatment of hemifacial spasm caused by a tortuous VA.

Vascular Decompression of Trigeminal and Facial Nerves in the Posterior Fossa under Endoscope-Assisted Keyhole Conditions

OBJECTIVE

The aim of this study was to determine the use and safety of the endoscope as an adjunct during trigeminal and facial nerve decompression procedures performed under keyhole conditions in the posterior fossa.

METHOD

We performed 67 surgeries in 65 patients with symptomatic trigeminal and facial nerve compression syndromes. The diagnosis was made mainly on the basis of clinical history, examination, and magnetic resonance imaging scans. Surgery was performed in all cases under endoscope-assisted keyhole conditions. The follow-up was 1 week postoperatively, 6 months, and then yearly up to 7 years. All 34 patients with trigeminal neuralgia received preoperative medication treatment and experienced failure with it. Eighteen patients out of 30 with hemifacial spasm had been previously treated with botulinum toxin injections. One patient suffered from both trigeminal neuralgia and facial spasm, because of a megadolichobasilar and vertebral artery with compression of both cranial nerves.

RESULTS

Sixty-four of the 65 patients became symptom free after surgical treatment; one revision surgery was necessary because of disappearance of the decompression muscle piece. No mortalities or minor morbidities were observed in this series.

CONCLUSION

A precise planned keyhole craniotomy and the simultaneous use of the microscope and the endoscope render the procedure of the decompression less traumatic.

Unusual recurrence of trigeminal neuralgia after microvascular decompression by muscle interposal

BACKGROUND

Patients with trigeminal neuralgia (TN) and persistent or recurrent facial pain after microvascular decompression (MVD) typically undergo less invasive procedures in the hope of providing pain relief. However, re-operation should be considered in selected patients.

CASE REPORT

A 48-year-old woman presented with recurrent trigeminal neuralgia (TN) 3 years following microvascular decompression (MVD). The patient underwent brain magnetic resonance angiography (MRA), which did not reveal neurovascular compression; therefore surgical re-exploration was carried out. During the operation, the fifth cranial nerve was seen without impingement from any blood vessels; however, a very firm tissue was observed and identified as the muscle fragment from the previous MVD procedure. The fifth cranial nerve was carefully separated from the muscle. Thereafter, the right SCA was dissected out from the muscle and suspended by a periosteum tape sutured to the nearby dura.

CONCLUSIONS

Our findings, along with similar cases reported in the literature, support the development of new inert materials and alternative surgical strategies that can limit TN recurrence.

[Adjunctive use of endoscopy during microvascular decompression in the cerebellopontine angle: 27 case reports]

Microvascular decompression is an important procedure for the management of microvascular compression syndromes in the cerebellopontine angle (CPA) like trigeminal neuralgia or hemifacial spasm. The ability to identify the offending vessel is the key to success. Can the endoscope help surgeons to identify and understand the responsible conflict in order to treat them? Our series concerns 27 consecutive patients who underwent microvascular decompression systematically using an endoscope with an angulation of 30° at the beginning and the end of the intervention. The decompression procedure was done under microscope. Endoscopic exploration was successful for all patients. Endoscopy improved visualization of the cranial nerves and allowed to see and understand the neurovascular conflicts, which were not able to be observed using the microscope alone for two of the 27 patients. The endoscope is a useful adjunct to microscopic exploration of the cranial nerves in the CPA avoiding significant cerebellar or brainstem retraction.

Surgical treatment of cranial neuralgias

The most common types of cranial neuralgias amenable to surgical therapeutic options are trigeminal neuralgia and glossopharyngeal neuralgia, the former having an approximate incidence of 5/100000 cases per year and the latter of 0.05/100000 cases per year. Surgical therapy of these pathological conditions encompasses several strategies, going from ablative procedures to neurovascular decompression, to radiosurgery. The choice of the most appropriate surgical option (which must be taken into account when all conservative treatments have proven to be unsuccessful) has to take into account many factors, the most important ones being neuroradiological evidence of a neurovascular conflict, severity of symptoms, the age and clinical history of the patient, and the patient's overall medical condition. In this chapter we report our experience with the treatment of trigeminal and glossopharyngeal neuralgia, describing the surgical procedures performed and reviewing the most recent aspects on this subject in the past literature.

Microvascular decompression for trigeminal neuralgia: the importance of a noncompressive technique--Kaplan-Meier analysis in a consecutive series of 330 patients

OBJECTIVE

Microvascular decompression, although a well-established procedure for treating primary trigeminal neuralgia, still has no standardized protocol. The practical consequences of having the implant keep the conflicting vessels apart, whether or not in contact with the root, is still in debate. The present work was undertaken to answer this question.

METHODS

Patients were segregated into 2 groups: Group I (260 patients) had a Teflon prosthesis implanted without contact to the root, and Group II (70 patients) had a similar implant with contact to the root. Cure rates in the 2 groups were compared at the latest follow-up (</=15 yr; average, 8.2 yr) using Kaplan-Meier analysis.

RESULTS

In Group I, the cure rate was 82% (214 of 260 patients), whereas in Group II, the cure rate was 67% (47 of 70 patients) (P = 0.01). Kaplan-Meier analysis of the follow-up period up to 15 years also shows a significant difference (P = 0.05).

CONCLUSION

These results strongly support the goal of performing the procedure without the implant in contact with the root. This is easier with the superior cerebellar artery, because of its laxity and small number of perforating branches, than with the anteroinferior cerebellar artery, which has perforators to the brainstem and labyrinthine artery arising from its cisternal portion. The significantly better long-term cure rate when the implant is not in contact with the root favors the "pure" decompressive effect of the microvascular decompression procedure, rather than a conduction block mechanism.

Recurrent trigeminal neuralgia secondary to Teflon felt

The authors present a case of a 45-year-old man with recurrent trigeminal neuralgia twelve years after microvascular decompression. The patient underwent surgical reexploration of the trigeminal nerve. A piece of hardened Teflon felt was found piercing a hole through the trigeminal nerve. No other compression of the nerve was found. Removal of the Teflon felt resolved the neuralgia. To the authors knowledge this is the first report of recurrent trigeminal neuralgia due to such a mechanism. This case emphasises the need for further improvement of the surgical technique for microvascular decompression of the trigeminal neuralgia.

Surgical treatment of trigeminal neuralgia without vascular compression: 20 years of experience

BACKGROUND

There are few reports on the outcome of surgical treatment of TGN without vascular compression.

METHODS

Between 1984 and 2004, 668 patients underwent MVD for TGN. In 21 patients (3.1%), vascular compression was absent. The surgical strategy in these cases involved the following: (1) dissection and exposure of the entire trigeminal nerve root; (2) slight neurapraxia with bipolar tips at the trigeminal nerve root; and (3) isolation of trigeminal nerve with Teflon sponge fragments.

RESULTS

The patients' (female/male, 20:1) ages ranged from 33 to 77 years. Their right side was the most frequently involved (61.9%). Their mean duration of pain before treatment was 7.6 years (range = 1-20 years). At surgical exploration, vascular compression or anatomical abnormalities were absent in 15 patients (71.4%), arachnoidal thickening was present in 5 (23.8%), and fiber dissociation of the trigeminal nerve was present in 1 (4.8%). Mean follow-up after surgery was 17.7 months (range = 4-65 months). Immediate relief from pain occurred in all 21 patients. On Kaplan-Meier analysis, recurrence was maintained at 14.8% for 12, 24, and 36 months, increasing to 43.2% at 48 months. Permanent hypoesthesia was present in 6 patients (28.6%), whereas loss of corneal reflex was observed transiently in 1 (4.8%). Motor function of the trigeminal nerve was intact in all patients. No other complication was found.

CONCLUSION

The proposed surgical plan of standard MVD plus slight trigeminal nerve root neurapraxia is a safe and effective management option for TGN without vascular compression.

[Management of recurrent trigeminal neuralgia after failed microvascular decompression]

OBJECTIVE

To evaluate the surgical management of patients with trigeminal neuralgia after failed microvascular decompression.

PATIENTS AND METHODS

Between 1993 and 2002, exploration of the posterior fossa was performed in 60 patients with trigeminal neuralgia. Records were analyzed retrospectively for those patients who needed another surgical procedure due to recurrence of pain, describing which procedure was performed, postoperative results and complications, and also the intraoperative findings when posterior fossa reexploration was realized.

RESULTS

Eighteen patients had trigeminal neuralgia recurrence requiring a new surgical intervention, that consisted in a fossa posterior reexploration in nine patients and percutaneous radiofrequency termal rhizotomy in the other nine patients. Among the repeat operations, there was negative exploration in 7 patients (77%), and a partial sensory rhizotomy was performed. Most of thermocoagulations (5/9) were performed in old patients or patients with anestesic contraindication for the fossa posterior reexploration.

CONCLUSION

Fossa posterior reexploration is an effective and safe surgical attitude in the treatment of recurrent trigeminal neuralgia after failed microvascular decompression. Partial sensory rhizotomy is recommended when the reexploration is negative.

Diagnostic significance of carbamazepine and trigger zones in trigeminal neuralgia

OBJECTIVE

To investigate the relationship between the efficacy of carbamazepine (CBZ) and the presence of the trigger zone for diagnosis of trigeminal neuralgia (TN). Study design CBZ was administered to 61 patients with suspected TN. All patients underwent intracranial examination by magnetic resonance imaging or computed tomography. The final diagnosis was established by oral and maxillofacial surgeon and neurosurgeon.

RESULTS

Of the 61 patients, 50 were finally diagnosed as having TN and 6 as having atypical facial pain. CBZ was effective for pain relief in 45 of the 50 TN patients (90%), and in 5 of the 11 patients (45%) with other diseases (P <.005). However, CBZ also relieved pain in some patients other than TN. Thirty of the 31 patients (97%) with a distinct trigger zone and 20 of the 30 (67%) without a trigger zone were diagnosed as having TN (P<0.005).

CONCLUSION

The efficacy of CBZ is an auxiliary indicator of TN and the presence of a distinct trigger zone is a strong indicator of TN.

Snare technique of vascular transposition for microvascular decompression--technical note

Recurrence of trigeminal neuralgia (TN) or hemifacial spasm (HFS) after microvascular decompression (MVD) is not rare. The prosthesis material eventually adheres to the neurovascular structures and again transmits arterial pulsation to the nerve. A snare ligature technique using a Gore-Tex tape can be used for the transposition of the offending artery. No prosthesis is necessary once the transposition is complete. This technique requires introduction of either Gore-Tex tape or thread around the artery and suture over the petrous dura, so an adequate working space as if operating in a shallow basin is essential. Therefore, the osteoplastic craniotomy is a little larger than usual with the scalp flap entirely reflected using a semicircular skin incision. The Gore-Tex tape can be directly snared around the artery and sutured over the petrous dura. If this procedure is difficult, a thread can be attached to both ends of the Gore-Tex tape to pass the tape around the vessel. Seven patients with TN and 13 patients with HFS have undergone this surgery. Although the follow-up period is not yet long enough, there has been no case of recurrence. The present technique for MVD can provide complete and permanent transposition of the offending artery.

Role of postoperative magnetic resonance imaging after microvascular decompression of the facial nerve for the treatment of hemifacial spasm

OBJECTIVE

This study was performed to investigate the role of postoperative three-dimensional short-range magnetic resonance angiography in the prediction of clinical outcomes after microvascular decompression (MVD) for the treatment of hemifacial spasm.

METHODS

We examined pre- and postoperative magnetic resonance imaging scans obtained between March 1999 and May 2000 for 122 patients with hemifacial spasm, to evaluate the degree of detachment of the vascular contact and changes in the positions of offending vessels. The degree of vascular decompression of the facial nerve root was classified into three groups, i.e., contact, partial decompression, or complete decompression. Contact was defined as unresolved compression, as indicated by postoperative three-dimensional short-range magnetic resonance angiography. Partial decompression was defined as incompletely resolved compression; vascular indentation of the facial nerve was improved, but contact with the facial nerve remained. Complete decompression was defined as completely resolved compression. These findings were compared with the surgical findings and clinical outcomes.

RESULTS

Of 122 patients with MVD, complete decompression of offending vessels at the root entry zone of the facial nerve was observed for 106 patients (86.9%), partial decompression was observed for 10 patients (8.2%), and contact with offending vessels was observed for 6 patients (4.9%) by using postoperative three-dimensional short-range magnetic resonance angiography. Our study demonstrated that the types of offending vessels affected neither the degree of decompression of the root entry zone of the facial nerve nor surgical outcomes (P > 0.05). Also, there was no significant relationship between the degree of decompression and improvement of symptoms (P > 0.05). Furthermore, there was no significant relationship between the degree of decompression and the timing of symptomatic improvement (P > 0.05).

CONCLUSION

Our data suggest that MVD of the facial nerve alone may not be sufficient to resolve symptoms for all patients with hemifacial spasm. Therefore, unknown factors in addition to vascular compression may cause symptoms in certain cases, and it may be necessary to remove those factors, simultaneously with MVD, to obtain symptom resolution.

Endoscopy in neuro-otologic surgery

Endoscopy offers several distinct advantages over the operating microscope during neuro-otologic surgery that make it an excellent adjunctive tool to the microscope or independent modality during cranial base surgery. The high magnification gives excellent definition of perforating blood vessels, cranial nerves, and neural structures, which in many cases is superior to that achieved with the microscope. Furthermore, the use of angled or flexible endoscopes allows one to look around corners and behind anatomic structures blocking the view seen via a 0 degree microscope. Endoscopy also has the theoretical advantage that a less invasive operative procedure is required, which should reduce the operative morbidity. Several notable disadvantages of endoscopy include the problems associated with blood soiling the endoscope, making visualization difficult or impossible, the lack of readily available instrumentation designed specifically for endoscopic neuro-otology, and the poor overview of the operative field. This last point is an important one because the endoscope is placed adjacent to the lesion and does not allow one to look backward to prevent [figure: see text] injury to structures next to the shaft of the telescope. Furthermore, the surgeon must be cognizant of potential thermal injury to structures caused by the heat generated by the light source. The present endoscopic technology limits the image that the surgeon sees to two dimensions, which results in certain unique problems when operating in a three-dimensional milieu. Because of this, there is a steep learning curve to acquire endoscopic dexterity and three-dimensional orientation. Finally, bimanual operation requires the use of an articulated endoscope holder or the commitment of the co-surgeon to hold the endoscope. One of the limitations of the operative microscope is that the angle of view is determined by the distance of the lens to the skull, retractor, or obstructing tissue, which is a function of the lens focal length; the longer the focal length, the narrower the viewing angle. During most microsurgical procedures, the focal distance varies between 200 and 400 mm. Using a previous analogy, if one looks through a door's keyhole at close range, nearly the entire room on the opposite side of the door can be seen, although nothing can be seen when the hole is viewed from a long distance. This is similar to what happens when using the endoscope with focal lengths ranging from 5 to 20 mm: a wider angle of view can be achieved. Based on their, experience the authors believe that endoscopes can be used safely during neuro-otologic surgery. As an adjunct to or substitution for the operative microscope, this modality does improve visualization of bony, neural, and vascular structures while minimizing cerebellar retraction.

Adjunctive use of endoscopy during posterior fossa surgery to treat cranial neuropathies

OBJECTIVE

The objective of this study was to determine the utility and safety of rigid endoscopy as an adjunct during posterior fossa surgery to treat cranial neuropathies.

METHODS

A suboccipital craniotomy was performed for 19 patients with non-neoplastic processes involving the Vth, VIIth, and/or VIIIth cranial nerves. Ten patients with trigeminal neuralgia (n = 8), hemifacial spasm (n = 1), or intractable tinnitus (n = 1) underwent primarily microvascular decompression procedures. One patient with geniculate neuralgia underwent nervus intermedius sectioning combined with microvascular decompression. Eight patients underwent unilateral vestibular nerve neurectomies for treatment of Meniere's disease. A 0- or 30-degree rigid endoscope was used in conjunction with the standard microscopic approach for all procedures.

RESULTS

All patients experienced resolution or significant improvement of their preoperative symptoms after posterior fossa surgery. The endoscope allowed improved definition of anatomic neurovascular relationships without the need for significant cerebellar or brainstem retraction. Cleavage planes between the cochlear and vestibular nerves entering the internal auditory canal and sites of vascular compression could not be microscopically observed for several patients; however, endoscopic identification was possible for all patients. There were no complications related to the use of the endoscope.

CONCLUSION

The rigid endoscope can be used safely during posterior fossa surgery to treat cranial neuropathies, and it allows improved observation of the cranial nerves, nerve cleavage planes, and vascular anatomic features without significant cerebellar or brainstem retraction.

Imaging the trigeminal nerve and pons before and after surgical intervention for trigeminal neuralgia

OBJECTIVE

To study the various imaging changes occurring in the trigeminal nerve and brainstem in patients before or after trigeminal neuralgia surgery.

METHODS

During a 7-year period, 275 patients with trigeminal neuralgia underwent high-resolution, contrast-enhanced magnetic resonance imaging (MRI) of the pons during gamma knife radiosurgery. Ninety-seven patients had no previous surgical intervention for trigeminal neuralgia, and 178 patients had undergone one or more previous procedures. Two independent observers, one of whom was blinded to patients' clinical details, reviewed MRI scans retrospectively. The analysis of the independent observers was then correlated with all previous therapeutic interventions.

RESULTS

One hundred one MRI scans demonstrated no radiological changes related to trigeminal neuralgia, and 174 MRI scans exhibited some radiological abnormality. The average axial plane diameter of the nerve for all patients was 4 mm (range, 2-6 mm). In the group that had not undergone previous surgery, 65 patients (67%) exhibited vascular compression. In the 88 patients who had undergone previous microvascular decompression, 21 (24%) had evidence of a pontine infarction. Twenty-six patients experienced facial sensory loss, 22 (88%) of whom had undergone previous surgery with evidence of a pontine infarction (n = 11) or perineural scarring (n = 6).

CONCLUSION

The majority of patients who had undergone previous trigeminal neuralgia surgery demonstrated readily identifiable abnormalities of the trigeminal nerve or brainstem. The frequency of such changes correlated with the type and number of procedures. Evidence of vascular compression was detected in the majority of patients. Most patients with postoperative facial sensory loss demonstrate changes in the nerve or pons on MR images.

Recurrent trigeminal neuralgia attributable to veins after microvascular decompression

OBJECTIVE

To demonstrate the cause of and optimal treatment for recurrent trigeminal neuralgia (TN) in cases where veins were observed to be the offending vessels during the initial microvascular decompression (MVD) procedure.

METHODS

An electronic search of patient records from 1988 to 1998 revealed that 393 patients were treated with MVD for TN caused by veins. The pain recurred in 122 patients (31.0%). Thirty-two (26.2%) of these patients underwent reoperations. Clinical presentations, recurrence intervals, surgical findings, and clinical outcomes were analyzed.

RESULTS

Analysis of 32 consecutive cases of recurrent TN initially attributable to veins revealed a female predominance (female/male = 26:5), with one female patient exhibiting bilateral TN caused by venous compression. Patient ages ranged from 15 to 80 years, with a prevalence in the seventh decade. The V2 distribution of the face was involved more frequently than other divisions. For 24 patients (75%), recurrence occurred within 1 year after the initial operation. At the time of the second MVD procedure, development of new veins around the nerve root was observed in 28 cases (87.5%). After successful subsequent MVD procedures, the pain was improved in 81.3% of the cases.

CONCLUSION

The recurrence rate for TN attributable to veins is high. If pain recurs, it is likely to recur within 1 year after the initial operation. The most common cause of recurrence is the development and regrowth of new veins. Even fine new veins may cause pain recurrence; these veins may be located beneath the felt near the root entry zone or distally, near Meckel's cave. Because of the variable locations of vein recurrence, every effort must be made to identify recollateralized veins. Given the high rate of pain relief after a second operation, MVD remains the optimal treatment for the recurrence of TN attributable to vein regrowth.

Microvascular decompression for trigeminal neuralgia: comments on a series of 250 cases, including 10 patients with multiple sclerosis

OBJECTIVE

To examine surgical findings and results of microvascular decompression (MVD) for trigeminal neuralgia (TN), including patients with multiple sclerosis, to bring new insight about the role of microvascular compression in the pathogenesis of the disorder and the role of MVD in its treatment.

METHODS

Between 1990 and 1998, 250 patients affected by trigeminal neuralgia underwent MVD in the Department of Neurosurgery of the "Istituto Nazionale Neurologico C Besta" in Milan. Limiting the review to the period 1991-6, to exclude the "learning period" (the first 50 cases) and patients with less than 1 year follow up, surgical findings and results were critically analysed in 148 consecutive cases, including 10 patients with multiple sclerosis.

RESULTS

Vascular compression of the trigeminal nerve was found in all cases. The recurrence rate was 15.3% (follow up 1-7 years, mean 38 months). In five of 10 patients with multiple sclerosis an excellent result was achieved (follow up 12-39 months, mean 24 months). Patients with TN for more than 84 months did significantly worse than those with a shorter history (p<0.05). There was no mortality and most complications occurred in the learning period. Surgical complications were not related to age of the patients.

CONCLUSIONS

Aetiopathogenesis of trigeminal neuralgia remains a mystery. These findings suggest a common neuromodulatory role of microvascular compression in both patients with or without multiple sclerosis rather than a direct causal role. MVD was found to be a safe and effective procedure to relieve typical TN in patients of all ages. It should be proposed as first choice surgery to all patients affected by TN, even in selected cases with multiple sclerosis, to give them the opportunity of pain relief without sensory deficits.

Posterior fossa reexploration for persistent or recurrent trigeminal neuralgia or hemifacial spasm: surgical findings and therapeutic implications

OBJECTIVE

To evaluate the surgical findings and subsequent therapeutic implications of posterior fossa reexploration for persistent or recurrent trigeminal neuralgia (TN) or hemifacial spasm (HFS) after failed microvascular decompression (MVD).

METHODS

Between December 1975 and October 1996, the senior author performed 31 reexplorations for failure or recurrence after MVD: 23 for TN and 8 for HFS. Records were analyzed retrospectively for evidence of vascular compression in primary and secondary operations, other pertinent intraoperative findings, intraoperative therapeutic interventions, and postoperative results and complications.

RESULTS

The previously placed polyvinyl alcohol foam (Ivalon sponge; Unipoint Industries, High Point, NC) or Teflon implant (Teflon felt; CR Bard, Inc., Bard Implants Division, Billerica, MA) was found to be in good position in 100% of the patients (31 of 31 patients). New vascular compression from an arterial source was found in three patients during posterior fossa reexploration: one with TN and two with HFS. New vascular compression from a venous source was observed in one patient with HFS. A scarred Ivalon sponge or Teflon implant with apparent mass effect on the nerve root was identified in seven reexplorations. One bony source of compression was seen. No new compressive elements or other sources of root irritation were appreciated in 61% of reexplorations. Partial sensory trigeminal rhizotomy was performed in 83% of reexplorations for persistent or recurrent TN. Of eight patients undergoing reexploration for persistent or recurrent HFS, six sustained complications.

CONCLUSION

Recurrent vascular compression was seldom identified during posterior fossa reexploration for failed MVD in patients with persistent or recurrent TN or HFS. The previously placed Ivalon sponge or Teflon implant was consistently found to be in good position. Partial sensory trigeminal rhizotomy is an often effective alternative in cases of recurrent TN when neurovascular compression is not identified. However, because of the relatively high incidence of complications associated with reexploration, we recommend other ablative or medical treatments for most patients after failed MVD for TN or HFS.