Role of endoscopy in the microvascular decompression for neurovascular conflicts in the cerebello-pontine angle

neurovascular conflict

Acta Neurochir (2013) 155:1709–1716

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

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

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

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

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

FU of our microvascular decompression operation for HFS

Acta Neurochir (2013) 155:1693–1697

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

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

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

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

Detecting the Offending Vessel in Hemifacial Spasm

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

Neurosurgery 73:58–67, 2013

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

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

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

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

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

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

PE-Hemifacial

Neurosurg Rev (2013) 36:297–302

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Microvascular decompression for treating hemifacial spasm: lessons learned from a prospective study of 1,174 operations

Neurosurg Rev (2010) 33:325–334.DOI 10.1007/s10143-010-0254-9

The authors critically analyzed a large series of patients with hemifacial spasm (HFS) and who underwent microvascular decompression (MVD) under a prospective protocol. We describe several “lessons learned” that are required for achieving successful surgery and proper postoperative management.

The purpose of this study is to report on our experience during the previous 10 years with this procedure and we also discuss various related topics.

From April 1997 to June 2009, over 1,200 consecutive patients underwent MVD for HFS. Among them, 1,174 patients who underwent MVD for HFS with a minimum 1 year follow-up were enrolled in the study. The median follow-up period was 3.5 years (range, 1-9.3 years). Based on the operative and medical records, the intraoperative findings and the postoperative outcomes were obtained and then analyzed. At the 1- year follow-up examination, 1,105 (94.1%) patients of the total 1,174 patients exhibited a “cured” state, and 69 (5.9%) patients had residual spasms. In all the patients, the major postoperative complications included transient hearing loss in 31 (2.6%), permanent hearing loss in 13 (1.1%), transient facial weakness in 86 (7.3%), permanent facial weakness in 9 (0.7%), cerebrospinal fluid leak in three (0.25%) and cerebellar infarction or hemorrhage in two (0.17%). There were no operative deaths.

Microvascular decompression is a very effective, safe modality of treatment for hemifacial spasm. MVD is not sophisticated surgery, but having a basic understanding of the surgical procedures is required to achieve successful surgery