Frequency and prognosis of delayed facial palsy after microvascular decompression for hemifacial spasm

Summary Background. Microvascular decompression (MVD) for hemifacial spasm (HFS) provides a long-term cure rate. Delayed facial palsy (DFP) is not an unusual complication, but it has only been sporadically described in the literature. The purpose of this report is to evaluate the incidence of delayed facial palsy after MVD and its clinical course and final results. Methods. From January, 1998 to April, 2004, 410 patients underwent microvascular decompression for hemifacial spasm at our Institute. During this time, 21 patients (5.4%) developed delayed facial weakness; eighteen of them were given steroid medication and they were followed up in the out-patient clinic. Findings. Twenty-one patients developed DFP after microvascular decompression an incidence of 5.4%. There were seventeen women (81.0%) among the 21 patients with DFP who were included in this study. In twenty of them, the symptoms of HFS improved completely after the operation, but the spasm remained with one of them. The onset of palsy occurred between postoperative day 7 and 23 (average: 12.1 days). The palsy was at least Grade II or worse on the House-Brackmann (HB) scale. The time to recovery averaged 5.7 weeks (range: 25 days–17 weeks); 20 patients improved to complete recovery and 1 patient remained with minimal weakness, as Grade II on the HB scale, at the follow-up examination. Conclusion. Our findings demonstrated that the incidence of DFP was not so low as has been reported the literature, and it did not have any striking predisposing factors. Even though the degree of facial palsy was variable, almost all patients exhibited a complete recovery without any further special treatment. The etiology of DFP and its association with herpes infection should be further clarified.     

Fusiform aneurysm of the vertebral artery presenting with hemifacial spasm treated by microvascular decompression

Summary We report a rare case of symptomatic hemifacial spasm caused by a fusiform vertebral artery aneurysm. A 59-year-old woman presented with left hemifacial spasm of 18 months duration. Magnetic resonance imaging showed an enlarged a fusiform aneurysm of the left vertebral artery which compressed the seventh cranial nerve at its exit from the caudal pons. Microvascular decompression of the facial nerve with moving of the aneurysm resulted in complete relief of the hemifacial spasm. No enlargement of the aneurysm was shown on follow-up for a period of 6 years.     

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.     

Intra-operative monitoring by facial electromyographic responses during microvascular decompressive surgery for hemifacial spasm

Summary The facial electromyographic response was monitored intraoperatively in 40 patients with hemifacial spasm who were operated on by microvascular decompression of the facial nerve. All 40 patients showed an abnormal facial electromyographic response (lateral spread response) with a latency of about 10 msec after stimulation. The abnormal response resolved before decompression in 22, resolved immediately with decompression in 16, and failed to resolve in two. Of the 38 patients in whom the abnormal response disappeared during surgery, 36 were postoperatively free from hemifacial spasm and two had mild hemifacial spasm. The two patients in whom the lateral spread response did not disappear during surgery showed persistent hemifacial spasm.In conclusion. Disappearance of the lateral spread response during surgery correlated with the absence of hemifacial spasm in the early postoperative period. The prognosis of hemifacial spasm was good in cases in whom the lateral spread response disappeared. Therefore, the authors think that intra-operative facial electromyography is very useful in assessing the efficacy of microvascular decompression and in predicting the prognosis of hemifacial spasm.     

不同剂量舒芬太尼术后镇痛方案对面肌痉挛微血管减压术后恶心呕吐的影响

目的:观察面肌痉挛微血管减压术后应用不同剂量舒芬太尼镇痛方案对术后恶心呕吐不良反应的影响。方法:回顾性纳入行微血管减压术的面肌痉挛女性患者183例,在相同麻醉方法的基础上根据术后是否使用舒芬太尼镇痛泵及其不同剂量将患者分为舒芬太尼2 μg/kg组（A组,60例）、舒芬太尼1 μg/kg组（B组,60例）和未使用镇痛泵组...     

Chronologic analysis of symptomatic change following microvascular decompression for hemifacial spasm: value for predicting midterm outcome

The objectives of this study are to categorize the patterns of symptomatic change and to chronologically analyze them. From January 2004 to February 2006, microvascular decompression was performed on 236 consecutive patients. Follow-up time was at least over 1 year (mean, 17.1 months). We categorized the postoperative courses into five different groups according to the similarity of the temporal changes of the residual symptoms. The symptomatic change during each follow-up interval was chronologically analyzed among five different groups. The five improvement patterns included group A (immediate recovery without relapse), group B (temporary relapse followed by cure), group C (slow but steady improvement that leads to cure after one or more months), group D (recurrence with sustained symptoms), and group E (no improvement or improvement to some extent that does not lead to cure). The symptomatic change in the successful groups (groups A, B, and C) differed from that in the unsatisfactory groups (groups D and E), especially during the follow-up interval between postoperative 3 weeks and 3 months (p = 0.014). This finding was true with (p = 0.029) or without (p = 0.015) the relapse curve. Therefore, we can predict the postoperative result as early as 3 months after the surgery. Overall cure rate in this series (93.2%) was nearly correspondent to the estimated cure rate at the first postoperative year (93.4%). Postoperative 3 months can be the most efficient and earliest time to predict the postoperative result.     

Microvascular decompression for primary hemifacial spasm. Importance of intraoperative neurophysiological monitoring

Summary There is considerable evidence that primary Hemi-Facial Spasm (HFS) is in almost all cases related to a vascular compression of the facial nerve at its Root Exit Zone (REZ) from brainstem, and that Micro-Vascular Decompression (MVD) constitutes its curative treatment. Clinical as well as electrophysiological features plead for mechanisms of the disease in structural lesions at the neural fibers (putatively: focal demyelination at origin of ephapses) and functional changes in the nuclear cells (hyperactivity of the facial nucleus). Lateral Spread Responses (LSRs) elicited by stimulation of the facial nerve branches testify of these electrophysiological perturbations. Monitoring LSRs during surgery is feasible; however the practical value of their intraoperative disappearance as control-test of an effective decompression remains controversial. MVD allows cure of the disease in most cases. Because the VIIIth nerve is at risk during surgery, intraoperative monitoring of Brainstem Auditory Evoked Potentials (BEAPs) is of value to reduce occurrence of hearing loss. Increase in latency of Peak V and decrease in amplitude of Peak I are warning-signals of an excessive stretching of the the cochlear nerve and impairment of the cochlear vascular supply, respectively.     

Microvascular decompression for hemifacial spasm: Outcome on spasm and complications. A review

Over the last decades microvascular decompression (MVD) has been established as the curative treatment of the primary Hemifacial Spasm (HFS), proven to be linked in almost all cases to a neurovascular compression of the facial nerve. Because the disease is not life-threatening and MVD not totally innocuous, efficacy and safety have to be weighted before decision taken of indicating surgery. The authors have been charged by the French Speaking Society of Neurosurgery to conduct a detailed evaluation of the probability of relief of the spasm that MVD is able to obtain, together with its potential complications. For the review, the authors have gone through the reports available from the Pubmed system. Eighty-two publications have been read and analysed, totalizing more than 10,000 operated cases. In most series, the percentage of patients with total relief ranged between 85% and 90%. Relief was obtained after a certain delay in as many as in 33% ± 8% of the patients in many series. For those, delay lasted around one year in 12% of them. When effect of MVD was considered achieved, relief remained permanent in all but 1%–2% of the long-term followed patients. As regards to complications, risk of permanent cranial nerve deficit was evaluated at 1%–2% for facial palsy, 2%–3% for non-functional hearing loss, 0.5%–1% for lower cranial nerve dysfunction. Risk of stroke was at 0.1% and mortality at 0.1%. CSF leakage and related complications could be reduced at less than 2% in most series provided careful closing techniques be applied. Complications were at a higher rate in repeated MVD. MVD is an effective curative method for almost all the patients affected with primary HFS. Because MVD for HFS is functional surgery, scrupulous consideration of its potential risks, together with the ways to avoid complications are of paramount importance. When MVD is estimated to have failed, it is wise to wait one year before considering to repeat surgery, as number of patients may benefit from delayed effect. This is the more so as important as repeated surgery entails a higher rate of complications.     

Results of reoperation for failed microvascular decompression

Summary Among 64 patients with hemifacial spasm (HFS) and 60 with trigeminal neuralgia (TN) treated by microvascular decompression (MVD), repeated MVD performed on 3 cases with HFS resulted in the absence of spasm in all cases. In 7 cases with TN, this technique resulted in complete remission in 2, recurrence in 3, and no pain relief in 2 cases. MVD was more effective on HFS than on TN in repeated procedures as well as for initial treatment. The cause of recurrence of HFS was attributed to the inadequate cushion effect of muscle as a prosthesis, while that for TN was suspected to be related more to post-operative fibrotic adhesions formed around the fifth nerve.     

Endoscope-assisted decompression of facial nerve for treatment of hemifacial spasm

Microvascular decompression has become the sole method for a curative treatment of primary hemifacial spasm. Finding the responsible conflicting artery is not always easy as its location can be deeply situated within the cerebellopontine/medullary fissure at the facial root exit zone. Sole or additional offending vessel(s) may be at the meatus of the internal auditory canal (5% of the cases). Identifying the compressive vessel(s) and performing decompression is in most cases possible without cerebellar retraction by classical microsurgical techniques. However, in a number of patients the neurovascular conflict may be hidden in spite of the direct illumination of the operative microscope. Therefore, assistance by endoscopy can be useful and contribute as a minimally invasive approach. The author reports his own experience in a series of 553 patients operated on over the past three decades. A total of 93.6% had complete relief of their spasm (11% after repeated surgery). Relief was delayed in 20.8% of these patients. Recurrence was rare (0.3%). There was no mortality and morbidity was low: deafness occurred in 0.6%. There was no permanent postoperative facial palsy. CSF leakage amounted to 1% in the last period of surgery. In conclusion, the author advocates combining the use of both the endoscopy for exploration and the microscope for decompression.     

微血管减压术治疗面肌痉挛的远期效果

目的：探讨微血管减压术治疗面肌痉挛1年以上的远期疗效。方法：对1987年7月至1999年6月间329例患者的临床资料及随访结果进行回顾性分析。结果：本组患者随访1－3年97例，痉挛完全缓解92．7％，明显缓解3．1％，部分缓解2．1％，无改变2．1％；3－5年77例，完全缓解92．2％，明显缓解3．9％，部分缓解1．3％，无改变占2．6％；5－10年121例，完全缓解90．9％，明显缓解4．1％，部分缓解2．5％，无改变2．5％；10年以上34例，痉挛综合缓解91．2％，明显缓解5．9％，无改变2．95。329例中主观满意度≥80％者占82．1％，痉挛复发率5．2％，并发症发生率5．5％，。结论：采用微血管减压术治疗面肌痉挛，尽量减少对脑神经及血管损伤，不遗漏面神经根附近的责任血管，是提高远期疗效养活并发症的重要环节。     

Cryptic cerebellopontine angle neuroglial cyst presenting with hemifacial spasm

Summary Hemifacial spasm (HFS) is commonly caused by a vascular loop compressing the Root Exit Zone (REZ) of the facial nerve. We report a case of HFS caused by a vascular loop that was abnormally displaced by a neuroglial cyst not seen in Magnetic Resonance Imaging (MRI). Microvascular decompression (MVD) was planned and the patient underwent a key-hole retromastoid posterior fossa exposure. A cystic lesion was found in the cerebellopontine angle (CPA), located around the seventh and eighth cranial nerves extending from the porous acousticus to the brainstem REZ of the facial nerve. The cyst wall was partially excised revealing the region of the neurovascular conflict. MVD of the facial nerve was performed with immediate postoperative complete resolution of the patient’s symptoms.     

A more Basal Approach in Microvascular Decompression for Hemifacial Spasm: The Para-Condylar Fossa Approach

Summary  Background. In view of the fact that a basal craniectomy in microvascular decompression (MVD) for hemifacial spasm (HFS) can minimize cerebellar retraction and expose the facial nerve root exit zone (FNREZ) directly from below without placement of tension on the seventh-eighth cranial nerve complex, we used a more basal approach in 32 patients with typical HFS.  Method. A slightly curved skin incision 5 cm in length and 2 cm posterior and parallel to the mastoid notch was made. The basal lateral occipital plate including the lateral one-fourth of the condylar fossa and the posterior one-fourth of the jugular process were removed. For the early drainage of cerebrospinal fluid through a small dural hole, the basal occipital plate posteromedial to the condylar fossa was removed. With this basal craniectomy, minimum elevation of the cerebellar tonsil and flocculus could expose FNREZ safely.  Findings. Thirty one of 32 patients displayed complete disappearance of spasm following surgery. One patient showed 70% decrease of spasm. Delayed transient facial weakness occurred in one patient. Audiometries showed no postoperative hearing decrease in any patient, even though no intra-operative monitoring of the cochlear function was undertaken.  Interpretation. Although this basal approach, the para-condylar fossa approach, is a slightly basal modification of the conventional procedure, it may minimize complications.     

Hemifacial spasm: neurovascular compressive patterns and surgical significance

Summary Background. The aim of this study was to report further investigation of neurovascular compression as a cause of hemifacial spasm (HFS) and to provide useful surgical guidelines by describing the compression patterns. Material and methods. From January 2004 to February 2006, 236 consecutive patients with HFS underwent microvascular decompression (MVD) in a single centre. Based on the operation and medical records, the intraoperative findings and post-operative outcomes were obtained and analysed. Results. We found that 95.3% of lesions had accompanying causative factors that made the neurovascular compression inevitable. Based on the contributing factors, compression patterns were categorised into six different types including: loop (n = 11: 4.6%), arachnoid (n = 66: 27.9%), perforator (n = 58: 24.6%), branch (n = 18: 7.6%), sandwich (n = 28: 11.9%), and tandem (n = 52: 22.0%). The compression patterns were significantly correlated with the compressing vessels involved. Thirty-two (86.5%) of 37 lesions where the vertebral artery was the compressing vessel involved the tandem type. Anterior inferior cerebellar artery was the compressing vessel involved in 49 (84.5%) of 58 perforator type compressions, while posterior inferior cerebellar artery was the compressing vessel involved in 8 (72.7%) of 11 loop type compressions. Conclusions. Once the compressing vessel responsible for the neurovascular compression are identified, the probable pattern of compression can be anticipated; this knowledge could facilitate the application of the appropriate operative procedures and minimise post-operative complications. Correspondence: Kwan Park, M.D., Ph.D., Samsung Medical Center, Department of Neurosurgery, School of Medicine, Sungkyunkwan University, 50 Ilwon-dong, Kangnam-gu, Seoul 135-710, South Korea.     

Teflon granuloma with midbrain cysts after microvascular decompression of the trigeminal nerve

Summary Granuloma formation is a known complication after microvascular decompression using Teflon fibers. Such granulomas commonly present with recurrent neuralgia whereas other symptoms are exceedingly rare. We report the first case of a multicystic lesion due to a Teflon granuloma that is also uncommon for the lack of recurrent neuralgia.     

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.     

Microvascular Decompression of the Facial Nerve for the Treatment of Hemifacial Spasm: Preoperative Magnetic Resonance Imaging Related to Clinical Outcomes

Summary  Background. The objective of this study was to investigate the role of preoperative three dimensional short-range magnetic resonance angiography (3D-TOF MRA) in predicting the clinical outcomes following microvascular decompression for the treatment of hemifacial spasm.  Method. Preoperative magnetic resonance (MR) imaging was performed on all patients with hemifacial spasm (564 cases) between January 1992 and September 1998. Of the 564 patients, 440 patients were included in this retrospective study. The presence of vascular contact, offenders, and anomalies in the vertebro-basilar system, were determined by 3D-TOF MRA prior to microvascular decompression of the facial nerve. The preoperative findings were compared with the surgical findings and clinical outcomes.  Findings. A correlation was found between the clinical outcome (p<0.01) and the presence of a vascular indentation at the root entry zone (REZ) of the facial nerve. A shift of the vertebrobasilar system to the symptomatic side was found in 214 (48.6%) patients with hemifacial spasm, compared to only 10 (13.5%) patients in the control group (p<0.01). The unilateral vertebral artery was observed in 43 (9.8%) patients with hemifacial spasm and in 8 (10.8%) of the control patients. A hypoplasia of the artery was found in 8 (1.8%) patients with hemifacial spasm and in 1 (1.4%) control patient. The compressing offenders in the patients, discovered by MRI in conjunction with MRA, were as follows: 45.9% (202 patients) in the anterior inferior cerebellar artery (AICA), 34.8% (153 patients) in the posterior inferior cerebellar artery (PICA), 12.5% (55 patients) in the vertebral artery (VA) and 6.8% (30 patients) in multiple vessels. In contrast to the compressing offenders seen on the MRA, the offenders confirmed during surgery were as follows: 43% (189 patients) in the AICA, 36.4% (160 patients) in the PICA, 1.4% (6 patients) in the VA, 19% (84 patients) in multiple vessels, and 0.2% (1 patient) in the vein.  In our long-term follow-up series of the 440 patients with hemifacial spasm, an excellent surgical outcome was obtained in 86.3% of cases and a good outcome was achieved in 6.4% (mean follow-up duration, 45.5 months).  Interpretation. Preoperative 3D-TOF MRA can identify the relationship between the facial nerve and adjacent vessels in patients with a hemifacial spasm and assist in preoperative planning. This study suggests that 3D-TOF MRA is useful for selecting appropriate patients for surgical treatment and, to some extent, as an additional role for predicting the clinical outcome.     

Frequency specific hearing improvement in microvascular decompression of the cochlear nerve

Summary Background. Microvascular compressions of the cochlear nerve can lead to hearing loss. Due to the tonotopic organization of the cochlear nerve any focal compression of the cochlear nerve will result in a frequency specific hearing loss. Decompressing the cochlear nerve could result in a frequency specific hearing improvement, without improving overall hearing.Method. Thirty one patients underwent microvascular decompression operations of the vestibulocochlear nerve for vertigo or tinnitus. Preoperative audiograms were substracted from postoperative audiograms obtained 2 years after microvascular decompression. The frequencies of maximal hearing improvement postoperatively were determined.Findings. Of the 31 patients studied, 19 had improvements of 5dB or more at one or more frequencies postoperatively, and 15 patients had improvements of 10dB or more. Three patients had improvements of 25dB or more postoperatively. The postoperative hearing improvement was frequency-specific and related to the anatomical location of the vascular contact on the auditory nerve. The improvement of hearing becomes diluted when the difference between pre- and postoperative hearing thresholds are averaged over all audiometric frequencies. We therefore present results for each frequency that was tested.Conclusions. Microvascular decompression of the cochlear nerve can improve hearing in selected patients. The improvement seems too small to justify decompressive surgery for the sole purpose of hearing improvement, but it could be considered if associated short vertigo spells, ipsilateral tinnitus, otalgia and cryptogenic hemifacial spasm are present. Decompression should be performed early, before BAEP changes become noticeable. 3D-MRI could become a valuable tool for selecting good surgical candidates.     

Gardner neurovascular decompression of the trigeminal and facial nerves for tic douloureux and hemifacial spasm

Neurovascular decompession of the trigeminal and facial nerves for tic douloureux and hemifacial spasm has been performed for the past two decades, starting with W. James Gardner in 1959. Although other neurosurgeons have refined and further perfected the operation, reporting large series of successful results, the credit for the concept and original procedures, including use of the surgical microscope, has generally escaped the attention of present-day neurological surgeons. This paper attempts to correct this inequity.     

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.