Surgical treatment of hemifacial spasm with zone-4 offending vessel

Background

Increasing evidence shows that vascular compression on any of the four zones of facial nerve may cause hemifacial spasms. Vascular compression on zone 4 (the cisternal portion) of the nerve is quite common, but only a very small percentage of such compression will elicit hemifacial spasm, because zone 4 is less susceptible than zone 3 (the root exit zone). Therefore, it seems difficult for the neurosurgeons to distinguish the real culprit vessels in zone 4. Here, our experience in treating vascular compression located in zone 4 of the facial nerve is reported.

Methods

Twelve patients of HFS due to compression of zone 4 were treated with microvascular decompression (MVD) surgery with the aid of combined monitoring of abnormal muscle response (AMR) and Z-L response (ZLR).

Results

All of the 12 patients had a zone 4 compression. In addition, there were vascular compressions on zone 3 (the root exit zone) and/or zone 2 (the attached segment) in six cases. AMR was absent in two cases, unstable in one case, and persisted after vascular decompression in another one case. ZLR was stable before decompression of zone 4 and disappeared after decompression in all cases. After MVD surgery, 11 patients were cured and one patient achieved good resolution of spasm. One patient had postoperative transient tinnitus.

Conclusions

The neurosurgeon should not ignore vascular compression at zone 4, especially when compressions at zones 2 and 3 co-exist. With the aid of AMR and ZLR, we are able to judge whether offending vessels exist at zone 4.     

Preoperative assessment of hemifacial spasm by the coronal heavily T2-weighted MR cisternography

Background

Microvascular decompression (MVD) has become a well-established surgical procedure for hemifacial spasm (HFS). Before surgery, it is essential to evaluate any possible deformity of the brainstem and establish the precise location of the offending vessels. In the present study of HFS patients we examined coronal sections taken by heavily T2-weighted MR cisternography in addition to routine axial sections, and assessed the usefulness of these images through comparison with intraoperative findings.

Methods

Eighty patients with HFS underwent preoperative coronal heavily T2-weighted MR cisternography before microvascular decompression surgery. Three neurosurgeons examined the preoperative axial and coronal MR images and evaluated vessel invagination into the brainstem. The usefulness of coronal sections was assessed statistically by the Mann-Whitney U test.

Results

Invagination of the offending vessel into the brainstem was observed in 24 cases (30.0%). In 19 patients, it was predicted preoperatively that compression of the flocculus and brainstem would be required in order to approach the offending vessels. Coronal MR cisternography was significantly more useful in cases with vessel invagination into the brainstem than in cases without invagination.

Conclusions

Coronal sections obtained by MR cisternography are able to demonstrate the severity of vessel invagination into the brainstem as well as revealing the presence of the offending vessel. This information is helpful for planning a suitable approach to the root exit zone.     

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

Background and objectives

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

Methods

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

Results

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

Conclusions

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

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.     

Continuous intraoperative monitoring of abnormal muscle response in microvascular decompression for hemifacial spasm; a real-time navigator for complete relief

Intermittent monitoring of abnormal muscle response (iAMR) has been reported to be useful for improving the surgical outcome of microvascular decompression (MVD) for hemifacial spasm (HFS). However, iAMR has not elucidated the relationship between AMR change and the corresponding surgical procedure, or the pathogenesis of AMR and HFS. The purpose of this study is to clarify the usefulness of continuous AMR monitoring (cAMR) for improving the surgical results of MVD and for understanding the relationship between AMR change and corresponding surgical procedure, and the pathogenesis of AMR and HFS. Fifty consecutive patients with HFS treated by MVD under cAMR monitoring, which continuously records AMR every minute throughout the surgical period, were retrospectively analyzed. The patients were assessed for the presence of HFS 1 week after the surgery and at final follow-up. Forty-six patients showed the complete disappearance of HFS. In 32, AMR disappeared abruptly and simultaneously with decompression of an offending vessel. AMR showed dynamic and various changes including temporary disappearance, or sudden, gradual, or componential disappearance before and during the decompression procedure, and even during the dural and skin closure after the initial decompression procedure. Facial spasm remained in four patients despite permanent AMR disappearance. cAMR monitoring improves the outcome of MVD. Although the main cause of HFS and AMR is vascular compression at the facial nerve, hyperexcitability of the facial nucleus is also involved in the pathogenesis of HFS and AMR. The proportional involvement of these causes differs between patients.     

Abnormal muscle response monitoring during microvascular decompression for hemifacial spasm

Summary Background. Several studies have investigated the relation between intraoperative abnormal muscle response (AMR) findings and postoperative results in patients undergoing microvascular decompression (MVD) for hemifacial spasm (HFS). However, there is some debate over the reliability of AMR as an indicator of postoperative outcome. We investigated whether AMR findings obtained during MVD reflect postoperative outcome in patients with HFS.Method. Subjects were 60 HFS patients who underwent AMR monitoring during MVD. AMR recordings were obtained from the mentalis muscle by electrical stimulation of the temporal branch of the facial nerve and from the orbicularis oculi muscles by stimulation of the marginal mandibular branch. Surgical outcome was compared with AMR findings at the completion of MVD. Mean follow-up was 61 months.Findings. HFS resolved completely in 50 patients in whom AMR disappeared intraoperatively and in 5 patients in whom the AMR amplitude was decreased at the end of MVD. Four patients showed HFS at the final follow-up examination despite cessation or decrease of AMR during surgery. In 1 patient, preoperative AMR waveforms persisted throughout MVD, but the postoperative outcome was excellent.Conclusions. Our findings suggest that intraoperative cessation or decreased amplitude of AMR at the end of surgery indicates a high likelihood of postoperative relief of HFS. We believe that intraoperative AMR monitoring is useful in MVD surgery for HFS.     

Microvascular decompression of the root emerging zone for hemifacial spasm: evaluation by fusion magnetic resonance imaging and technical considerations

Object

The root exit zone (RExZ) of the facial nerve has been considered to be the target in microvascular decompression (MVD) for hemifacial spasm. However, more proximal segments with oligodendrocyte-derived myelin, where the facial nerve root emerges at the pontomedullary sulcus and adheres to the brainstem surface (root emerging zone [REmZ]), may also be susceptible to neurovascular compression. This study evaluated the predictive value of magnetic resonance (MR) imaging in detecting and assessing the features of vascular compression, especially in the pontomedullary sulcus, and describes the technical considerations of MVD procedures for the more proximal segments of the facial nerve.

Methods

Twenty patients treated with MVD underwent three-dimensional constructive interference in steady-state MR imaging and three-dimensional time-of-flight MR angiography. Their fusion images were used to evaluate the anatomical neurovascular relationships and intraoperative findings were analyzed.

Results

Most offending arteries at the REmZ and the RExZ of the facial nerve were correctly identified by fusion MR imaging. During surgery, neurovascular contacts were identified at one or more segments of the facial nerve in all patients. The REmZ of the facial nerve was affected in 55 % of the patients. The most common offending vessel at the REmZ was the posterior inferior cerebellar artery rather than the anterior inferior cerebellar artery. The key procedure to explore the deep-seated REmZ in the pontomedullary sulcus was full dissection of the lower cranial nerves to the brainstem origin.

Conclusions

Our definition more correctly describes the specific anatomical relationship of the facial nerve origin from the brainstem and the clinically relevant target for MVD surgery. Fusion MR imaging is very useful to identify neurovascular contacts at both the RExZ and the REmZ of the facial nerve.     

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.     

Emprical factors associated with Brainstem auditory evoked potential monitoring during microvascular decompression for hemifacial spasm and its correlation to hearing loss

Background

Cranial nerve VIII is at risk during microvascular decompression (MVD) for hemifacial spasm (HFS). The primary aim of this study is to evaluate the empirical factors associated with brainstem auditory evoked potential monitoring and its correlation to post operative hearing loss (HL) after MVD for HFS.

Methods

Pre-operative and post-operative audiogram data and BAEP from ninety-four patients who underwent MVD for HFS were analyzed. Pure tone audiometry (PTA) and Speech Discrimination Score (SDS) were performed on all patients before and after surgery. Intraoperative neurophysiological data were reviewed independently. HL was assessed using the AAO-HNS classification system for non-serviceable hearing loss (Class C/D), defined as PTA >50 dB and/or SDS <50 % within the speech range of frequencies.

Results

Patients with HL had higher rates of loss in the amplitude of wave V and prolongation in the interpeak latency of peak I-V latency during MVD. Gender, age, side, and MVD duration did not increase the risk of HL. There was no correlation between successive number of BAEP changes (reflective of the number of surgical attempts) and HL. There was no association between the speed of recovery of BAEPs and HL.

Conclusions

Patients with new post-operative HL have a faster rate of change in the amplitude of wave V and the interpeak I-V latency during intraoperative BAEP monitoring for HFS. Our alarm criteria to inform the surgeon about impending nerve injury might have to be modified and prospectively tested to prevent rapid change in BAEPs.     

A proposal for standardized analysis of the results of microvascular decompression for trigeminal neuralgia and hemifacial spasm

Background

The purpose of this study was to evaluate and analyze overall postoperative results from microvascular decompression (MVD) by combining the cure rate of symptoms with the complication rate. A new scoring system for obtaining objective surgical results from MVD for trigeminal neuralgia (TN) and hemifacial spasm (HFS) is proposed to document treatment results using consistent criteria in a standardized manner.

Method

Surgical results combining complications , if any, were obtained from a questionnaire sent to patients who had undergone surgery for TN or HFS in recent years and had been followed-up for more than 1?year after surgery (TN patients, n?=?54; HFS patients, n?=?81) When surgical outcome is complete resolution of symptoms, the efficacy of surgery (E) is designated E-0, but when moderate symptoms are still persist postoperatively, the score is designated E-2. When no complications are seen after surgery, the complication score (C) is C-0, while the score is C-2 if troublesome complications remain. In addition, total evaluation of the results (T) is judged by combining the E and C scores. For example, when E is 0, and C is C-2, the total evaluation is scored as T-2, which is diagnosed as fair.

Findings

The response rate of the questionnaire was 80.7% (109/135). Overall surgical data were evaluated and analyzed using our new scoring system. Analysis of the collected data revealed an outcome of T-0 was 70% (35/50 patients) and T-1 was 24% (12/50) and T-2 was 6% (3/50) in TN, whereas in HFS, T-0 was 61% (36/59) and T-1 was 27.1% (16/59) and T-2 was 6.8% (4/59) and T-3 was 5.1% (3/59).

Conclusion

The total results of MVD should be evaluated and analyzed by combining the cure rate of symptoms together with the complication rate. This new scoring system could allow much more objective analysis of the results of following MVD. Adopting this scoring system to objectively judge treatment results for TN and HFS, individual surgeons can compare their own overall surgical results with those of other institutes. Comparative results of MVD can also be provided to patients considering therapy to allow informed decision-making on the basis of good quality evidence.     

A recommendation on the basis of long-term follow-up resultsof our microvascular decompression operation for hemifacial spasm

Background

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

Methods

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

Results

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

Conclusions

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

Relationship between angiographical manifestations and operative findings in 100 cases of hemifacial spasm

Relationship between angiographical manifestations and operative findings of hemifacial spasm was studied in 100 cases. Vertebral angiography was performed, and Towne, straight AP, and lateral projections were routinely studied. The anterior inferior cerebellar artery (AICA) directly compressed the facial nerve root exit zone in 54 instances, the posterior inferior cerebellar artery (PICA) in 38, and the vertebral artery (VA) in 11. Compressions by multiple vessels were observed in 3 cases. Anatomical variations of the AICA and the PICA were classified into 3 groups according to their origins and their distributions of blood supply: Type I, normal distribution of AICA and PICA; Type II, common trunk anomaly with dominant AICA (basilar artery origin); and Type III, common trunk anomaly with dominant PICA (vertebral artery origin). In our cases, 35% of them showed normal distribution, 34% dominant AICA, and 35% dominant PICA. Analyses of the angiograms revealed significantly increased numbers of common trunk anomalies when compared with normal angiograms studied by Takahashi. In 60 of the 65 cases with common trunk anomalies, facial nerves were compressed by the main trunk or the branches of the dominant artery. There were 35 cases which belonged to Type I anatomical classification. They were subdivided into 2 groups according to the size of the AICA and PICA: 1. AICA greater than PICA, and, 2. PICA greater than AICA. In the AICA greater than PICA subgroup, the AICA was the offending artery in all but one case. In the PICA greater than AICA subgroup, the PICA was responsible in 9 of 17 cases. In 31 cases, angiograms showed a redundant VA with lateral elongation into the cerebellopontine angle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Microvascular decompression for neurovascular conflicts in the cerebello-pontine angle: which role for endoscopy?

Background

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

Methods

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

Results

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

Conclusion

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

3D Computer graphics simulation to obtain optimal surgical exposure during microvascular decompression of the glossopharyngeal nerve

The affected artery in glossopharyngeal neuralgia (GPN) is most often the posterior inferior cerebellar artery (PICA) from the caudal side or the anterior inferior cerebellar artery (AICA) from the rostral side. This technical report describes two representative cases of GPN, one with PICA as the affected artery and the other with AICA, and demonstrates the optimal approach for each affected artery. We used 3D computer graphics (3D CG) simulation to consider the ideal transposition of the affected artery in any position and approach. Subsequently, we performed microvascular decompression (MVD) surgery based on this simulation. For PICA, we used the transcondylar fossa approach in the lateral recumbent position, very close to the prone position, with the patient’s head tilted anteriorly for caudal transposition of PICA. In contrast, for AICA, we adopted a lateral suboccipital approach with opening of the lateral cerebellomedullary fissure, to visualize better the root entry zone of the glossopharyngeal nerve and to obtain a wide working space in the cerebellomedullary cistern, for rostral transposition of AICA. Both procedures were performed successfully. The best surgical approach for MVD in patients with GPN is contingent on the affected artery—PICA or AICA. 3D CG simulation provides tailored approach for MVD of the glossopharyngeal nerve, thereby ensuring optimal surgical exposure.     

Results of microvascular decompression in 16 cases of glossopharyngeal neuralgia

Seven males and nine females with glossopharyngeal neuralgia were treated by microvascular decompression (MVD) over a 4-year period. Their ages ranged from 40 to 72 years (average, 54.7 years). The duration of pain ranged from 2 months to 13 years, and all except one patient had brief attacks of lancinating pain in the throat and/or ear. One patient reported dull, paroxysmal throat pain. At surgery, vascular compression of the 9th and 10th nerves at the root entry-exit zone was observed in all cases. The offending vessels were the posterior inferior cerebellar artery (PICA) in 11 cases, the PICA and the anterior inferior cerebellar artery (AICA) in two, the PICA and vertebral artery (VA), and AICA and VA in one case each. The patient with atypical pain had compression by a large vein. In 15 cases of arterial compression, the pain completely disappeared after MVD, and there was no recurrence during the follow-up period, which ranged from 1 month to 4 years. One patient with venous compression had significant pain relief, although mild throat pain persists. In one case, postoperative complications included transient 6th, 7th, and 10th nerve palsies and sensory disturbance, which were assumed to be due to disturbance of the circulation in the perforating branches from the compressing artery. The experience with these 16 patients indicates that vascular compression is the etiology of glossopharyngeal neuralgia and that MVD provides excellent results.     

Early permanent disappearance of abnormal muscle response during microvascular decompression for hemifacial spasm: a retrospective clinical study

The objective of this study is to explore the cause of early abnormal muscle response (AMR) disappearance during microvascular decompression for hemifacial spasm and the clinical outcomes of these patients. Three hundred seventy-two patients received microvascular decompression (MVD) under intraoperative electrophysiological monitoring in Nanjing Drum Tower Hospital in 2014; the characteristic AMR of HFS was observed in 359 patients during the operation. And the 359 patients were divided into two groups based on whether AMR had remained before the beginning of the decompression procedure for offending vessels. Thirty-three patients who showed a permanent disappearance of AMR before the beginning of decompression were regarded as group I. Dural opening and the succeeding CSF drainage produced a permanent disappearance of AMR in 13. During the dissection of lateral cerebellomedullary cistern, a permanent disappearance of AMR was found in 20 patients. Thirty-two patients were cured immediately; delayed resolution (7 days after surgery) was found in one patient. No complications were observed and no recurrence was found during the follow-up period in the 33 patients. In the other 326 patients (group II), AMR disappeared temporarily before the beginning of the decompression procedure for offending vessels in 42 patients. After decompression, AMR disappeared completely in 305 patients. Two hundred sixty-seven patients were cured immediately and 57 patients got a delayed resolution (2 days to 45 weeks after surgery). The two left did not get a complete abolition of spasm. Three cases of hearing loss, one hoarseness, and nine delayed facial paralysis were observed. The reason of early abnormal muscle response disappearance may be that the degree of neurovascular compression was not serious; these patients were more likely to get an immediate cure. Continuous intraoperative electrophysiological monitoring of AMR is necessary.     

Abnormal muscle response monitoring during microvascular decompression for hemifacial spasm and long term results

OBJECTIVE: There is some debate over the reliability of intraoperative abnormal muscle response (AMR) monitoring as an indicator of postoperative long-term outcome in patients with hemifacial spasm (HFS). We investigated whether AMR findings obtained during microvascular decompression reflect postoperative long-term outcome. MATERIAS AND METHODS: Subjects were 51 HFS patients who underwent AMR monitoring during surgery. AMR recordings were obtained from the mentalis muscle by electrical stimulation of the temporal branch of the facial nerve and from the orbicularis oculi muscles by stimulation of the marginal mandibular branch. Postoperative follow-up was more than 5 years (range 61-118 months, mean 87 months). RESULTS: In 37 patients, AMR disappeared after vascular decompression. Among those patients, only one presented with spasm at the final follow-up examination. In 6 of 7 patients with AMR that disappeared early before the completion of decompression, hemifacial spasm resolved completely. Five of six patients in whom AMR still remained but with decreased amplitude at the end of surgery experienced complete resolution. CONCLUSIONS: Our findings suggest that intraoperative cessation including prior to decompression or decreased amplitude of AMR at the end of surgery indicates a high likelihood of postoperative long-term relief of HFS. We believe that intraoperative AMR monitoring is useful in MVD surgery for HFS.     

Postoperative Oblique Sagittal MR Imaging of Microvascular Decompression for Hemifacial Spasm

Summary  Pre-operative and postoperative oblique sagittal gradient-echo magnetic resonance (MR) imaging was used to evaluate microvascular decompression of the facial nerves in 26 patients with hemifacial spasm. The pre-operative MR images were divided into two groups as follows: 22 images in Group I, clear imaging of a high-intensity line and/or spot at the root exit zone (REZ) of the facial nerve; and 4 in Group II, and unreliable image around the REZ. Surgery found that the causative vessel was the vertebral artery (VA) in 9 cases and the anterior inferior cerebellar artery (AICA) or the posterior inferior cerebellar artery (PICA) in 13 cases in Group I, and the AICA or the PICA in the 4 cases in Group II. Postoperative MR imaging showed clear decompression as the high-intensity line and/or spot completely separated from the REZ by a low- and/or iso- intensity area in 9 cases of VA compression repositioned to the petrous dura mater, in 11 cases of PICA or AICA compression treated by shredded Teflon pledgets in Group I and in 3 cases in Group II. Postoperative MR imaging showed an incomplete separation of any high-intensity line and/or spot in the REZ in 2 cases of PICA or AICA compression in Group I and in one in Group II. The outcome was excellent in 22 of 23 cases with clear decompression, and in 1 of 3 cases of unclear decompression. Hemifacial spasm persisted in 3 cases. Oblique sagittal gradient-echo MR imaging is a useful method for postoperative follow-up which can demonstrate changes around the REZ of the facial nerve if hemifacial spasm recurs.     

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.