Advances in microvascular decompression for hemifacial spasm

Primary hemifacial spasm(HFS) is a disorder that causes frequent involuntary contractions in the muscles on one side of the face, due to a blood vessel compressing the nerve at its root exit zone(REZ) from the brainstem. Numerous prospective and retrospective case series have confirmed the efficacy of microvascular decompression(MVD) of the facial nerve in patients with HFS. However, while MVD is effective, there are still significant postoperative complications. In this paper, recent technological advances related to MVD(such as lateral spread response,brainstem auditory evokes potential, three dimensional time of flight magnetic resonance angiography, intraoperative neuroendoscopy) are reviewed for the purposes of improving MVD treatment efficacy and reducing postoperative complications.

Three-dimensional time-of-flight magnetic resonance angiography combined with high resolution T2-weighted imaging in preoperative evaluation of microvascular decompression

BACKGROUND Neurovascular compression(NVC) is the main cause of primary trigeminal neuralgia(TN) and hemifacial spasm(HFS). Microvascular decompression(MVD) is an effective surgical method for the treatment of TN and HFS caused by NVC. The judgement of NVC is a critical step in the preoperative evaluation of MVD, which is related to the effect of MVD treatment. Magnetic resonance imaging(MRI) technology has been used to detect NVC prior to MVD for several years. Among many MRI sequences, three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA) is the most widely used. However, 3D TOF MRA has some shortcomings in detecting NVC. Therefore, 3D TOF MRA combined with high resolution T2-weighted imaging(HR T2WI) is considered to be a more effective method to detect NVC.AIM To determine the value of 3D TOF MRA combined with HR T2WI in the judgment of NVC, and thus to assess its value in the preoperative evaluation of MVD.METHODS Related studies published from inception to September 2022 based on PubMed, Embase, Web of Science, and the Cochrane Library were retrieved. Studies that investigated 3D TOF MRA combined with HR T2WI to judge NVC in patients with TN or HFS were included according to the inclusion criteria. Studies without complete data or not relevant to the research topics were excluded. The Quality Assessment of Diagnostic Accuracy Studies checklist was used to assess the quality of included studies. The publication bias of the included literature was examined by Deeks’ test. An exact binomial rendition of the bivariate mixed-effects regression model was used to synthesize data. Data analysis was performed using the MIDAS module of statistical software Stata 16.0. Two independent investigators extracted patient and study characteristics, and discrepancies were resolved by consensus. Individual and pooled sensitivities and specificities were calculated. The I_(2) statistic and Q test were used to test heterogeneity. The study was registered on the website of PROSERO(registration No. CRD42022357158).RESULTS Our search identified 595 articles, of which 12(including 855 patients) fulfilled the inclusion criteria. Bivariate analysis showed that the pooled sensitivity and specificity of 3D TOF MRA combined with HR T2WI for detecting NVC were 0.96 [95% confidence interval(CI): 0.92-0.98] and 0.92(95%CI: 0.74-0.98), respectively. The pooled positive likelihood ratio was 12.4(95%CI: 3.2-47.8), pooled negative likelihood ratio was 0.04(95%CI: 0.02-0.09), and pooled diagnostic odds ratio was 283(95%CI: 50-1620). The area under the receiver operating characteristic curve was 0.98(95%CI: 0.97-0.99). The studies showed no substantial heterogeneity(I2 = 0, Q = 0.001 P = 0.50).CONCLUSION Our results suggest that 3D TOF MRA combined with HR T2WI has excellent sensitivity and specificity for judging NVC in patients with TN or HFS. This method can be used as an effective tool for preoperative evaluation of MVD.

MICROVASCULAR DECOMPRESSION FOR HEMIFACIAL SPASM - TECHNICAL NOTES AND COMPLICATION PREVENTION : EXPERIENCE OF 338 CASES

Objective To summarize our clinical experience of microvascular decompression (MVD)for medically intractable hemifacial spasm(HFS) patients with emphasis on microsurgical manipulation and to improve cure rate and avoid surgical complications. Methods Three hundred and thirty-eight patients with HFS underwent MVD under general anesthesia . With the help of 'zero retraction' technique, prosthesis can be properly inserted between offending vessel loop and affected facial nerve REZ in a 'rolling ball' fashion under operative microscope. Results Surgical intervention achieved high relief rate of 91 .4% and no major complications, with low recurrence rate of only 3.2% after averaging more than two years' follow-up ( M = 32 months). Conclusion It is possible to approach to the facial nerve REZ with 'zero retraction', which is fundamentally important to clear from cranial nerve and cerebellar injury. Skilled microsurgical technique along with correct recognition and mobilization of offending vessels are a must to assure MVD a highly efficacious and low risk treatment of choice for HFS patients.

Complications of microvascular decompression in hemifacial spasm treatment Retrospective analysis of 156 cases

BACKGROUND： Microvascular decompression has become a well-accepted, safe method in the treatment of hemifacial spasms. However, postoperative complications exist and influence the prognosis of the disease. OBJECTIVE： This study aimed to analyze, by case review, the characteristics and regularity of microvascular decompression complications in the treatment of hemifacial spasm. DESIGN： Retrospective analysis. SETTING： Beijing General Group Hospital of the Chinese People＇s Armed Police Forces. PARTICIPANTS： A total of 156 patients with hemifacial spasm were admitted to the Department of Neurosurgery, Beijing General Group Hospital of the Chinese People＇s Armed Police Forces from June 2004 to June 2006 and recruited for this study. The patients, 57 males and 99 females, averaged 46 years of age （range 17-68-years old）. All suffered from facial innervated muscular paroxysmal and recurrent contraction, which could not be controlled by consciousness. Electromyogram demonstrated waves of fibrillation and fasciculation. Prior to admission, all patients had received other treatments. Written informed consents for treatment were obtained from all patients. This protocol was approved by the Hospital＇s Ethics Committee. METHODS： After anesthesia, a cranial bone pore was drilled below the connection of the lateral sinus and sigmoid sinus. Dura mater was dissected at the ＂⊥＂ shape and held in the air. Under microscopy, the flocculus cerebelli was lifted slightly up for convenient observation of the cerebellopontine angle. The mucous membrane was sharply separated. Corresponding vessels were identified at the root of the facial nerves and subsequently liberated and disassociated from the root exit zone. Suitably sized Teflon cotton was placed between the corresponding vessels and brain stem. MAIN OUTCOME MEASURES： Complications of microvascular decompression. RESULTS： All 156 patients participated in the final analysis. （1） Postoperatively, 66 （42%） patients presented with obvious headache or dizziness, 5 （3%） with severe headache, 43 （28%） with nausea or vomiting for 12 hours to 3 days, and 19 （12%） with aseptic meningitis and a body temperature of 37.5-40 ℃ Patients, who suffered from headache and fever, were cured after 2-5 lumbar punctures. （2） Postoperatively, 19 （8%） patients suffered from short-term dysaudia and tinnitus on the affected side, 9 （6%） from mild hemifacial spasms, and 2 （1%） from ambiopia. All patients were cured after treatment with a neurotrophic drug. （3） Postoperatively, 4 （2%） patients suffered from cerebrospinal fluid incision leakage and 2 （1%） from cerebrospinal rhinorrhea. The cerebrospinal fluid incision was tightly sutured. One case of cerebrospinal rhinorrhea was cured after mastoid process repair, and the other one recovered spontaneously. CONCLUSION： Experimental results have indicated that low intracranial pressure is the main complication of microvascular decompression in patients with hemifacial spasms, and no permanent neuro-functional impairment was found.

Microvascular decompression for a patient with oculomotor palsy caused by posterior cerebral artery compression:A case report and literature review

BACKGROUND Aneurysm compression,diabetes,and traumatic brain injury are well-known causative factors of oculomotor nerve palsy(ONP),while cases of ONP induced by neurovascular conflicts have rarely been reported in the medical community.Here,we report a typical case of ONP caused by right posterior cerebral artery(PCA)compression to increase neurosurgeons’awareness of the disease and reduce misdiagnosis and recurrence.CASE SUMMARY A 54-year-old man without a known medical history presented with right ONP for the past 5 years.The patient presented to the hospital with right ptosis,diplopia,anisocoria(rt 5 mm,lt 2.5 mm),loss of duction in all directions,abduction,and light impaired pupillary reflexes.Magnetic resonance angiography and computed tomography venography examinations showed no phlebangioma,aneurysm,or intracranial lesion.After conducting oral glucose tolerance and prostigmin tests,diabetes and myasthenia gravis were excluded.Cranial nerve magnetic resonance imaging showed that the right PCA loop was in direct contact with the cisternal segment of the right oculomotor nerve(ON).Microvascular decompression(MVD)of the culprit vessel from the ON through a right subtemporal craniotomy was carried out,and the ONP symptoms were significantly relieved after 3 mo.CONCLUSION Vascular compression of the ON is a rare pathogeny of ONP that may be refractory to drug therapy and ophthalmic strabismus surgery.MVD is an effective treatment for ONP induced by neurovascular compression.

Long-term efficacy of microvascular decompression on trigeminal neuralgia and multi-factor research of recurrence

Objective To research the factors that affects the efficacy of 2 826 cases of of trigeminal neuralgia after microvascular decompression during follow-up more than 1 year. Methods The patients with trigeminal meuralgia were followed-up for 1-25 years ( mean 9. 8 years) after microvascular decompression from January 1984 to

Microvascular decompression in patients with hemifacial spasm: report of 1200 cases

Background Microvascular Decompression (MVD) operation is the most reliable treatment for hemifacial spasm (HFS), but it causes many complications. The aim of this retrospective study was to investigate the factors relavent to the effects and postoperative complications of microvascular decompression on hemifacial spasm. Methods A total of 1200 HFS patients treated with MVD were studied retrospectively. The root exit zone (REZ) of the facial nerve was exposed through the infraflocculus approach, the offending vessels were identified and separated from the REZ, and a Teflon graft was interposed between the offending vessels and the brain stem. Brain stem auditory evoked potential (AEP) was monitored intraoperatively. Results The offending vessels can be identified in all patients. The anteroinferior cerebellar artery was the main offending vessel (42.6%). Patients with vertebral artery compression had a multiple vascular compression fashion. Follow-up for 2-10 years (mean 4.2 years) showed that 88.7% patients were cured and 5.6% relieved, with an effective rate of 94.3%. Recurrence rate was 3.2%, and the ineffective rate was 2.6%. The most frequent complication was hearing dysfunction (2.8%). Conclusions MVD is the most definitive treatment method of HFS. The key procedures of this operation include adequate exposure of the REZ, identification of the offending vessels, and proper positioning of Teflon grafts. Complications can be reduced effectively by utilizing a real-time AEP monitoring during the operation.

MICROVASCULAR DECOMPRESSION FOR TRIGEMINAL NEURALGIA

Of 42 patients undergoing a microvascular decompression for trigemiaal neuralgia with a follow-up of 4 to 7 years,32(76.19%)had no postoperative recurrence of neuralgic pain,4(9.52%)had a minor recurrence and 6 (14.29%) had a major recurrence.It was considered that the neuralgic recurrence might be dae to some possibly missed pathogenis vessel during operation or a new compression of the trigeminal nerve root occuring after operatoin.

The ideal microvascular decompression technique should be easy and safe

Microvascular decompression(MVD) surgery has been popularized as an etiological treatment around the world for more than half a century. However, as a functional operation in the cerebellopontine angle, this process should be refined to enhance cure and minimize complication. After accomplishing more than 10,000 MVDs, we have learned the following concerning the operative technique:(1) the principle of MVD is to separate the neurovascular confliction, rather than isolate with prostheses;(2) identification of the conflict relies on good exposure;(3) a satisfactory working space can be created by the appropriate positioning, i.e., either a close-to-the-sigmoid craniectomy or caudorostral approach;(4) a sharp dissection of arachnoids leads to a maximal visualization of the entire intracranial course of the nerve root;(5) all vessels contacting the trigeminal nerve root should be cleared off;(6) intraoperative electrophysiological monitoring may predict the prognosis of hemifacial spasm and guide the operation; and(7) the dura must be closed with watertight stitches at the end.

Quantitative assessment of sensory functions after 3 surgical approaches for trigeminal neuralgia by current perception threshold measurement

Objective： To quantitatively identify and grade trigeminal sensory functions after 3 major surgical procedures of trigeminal neuralgia using a newly developed quantitative sensory testing technique, current perception threshold measurement （CPTM）. Methods： In the current study, there were 48 trigeminal neuralgia patients without history of prior surgical treatment. These patients received one of the following 3 surgical procedures, microvascular decompression （MVD）, peripheral nerve block with alcohol （PNB）, or percutaneous radiofrequency thermocoagulation （PRFT）. The quantitative sensory testing measurement, CPTM, and conventional qualitative sensory testing measurements were performed preoperatively and postoperatively to evaluate and grade the trigeminal sensory functions All 3 major cutaneous sensory fiber types, large myelinated fibers （A beta）, small myelinated fibers （A delta） and unmyelinated fibers（C） were allowed to quantitatively evaluate and grade by CPTM. The results of the measurements were statistically analyzed using a one-way analysis of variance （single factor）. Each subject was his/her own control for comparison of the preoperative to postoperative state on the asymptomatic and symptomatic sides. Subjects were tested 48 h preoperatively and 4 weeks postoperatively. Results： PNB with alcohol and PRFT caused significant sensory dysfunction postoperatively in every fiber type, indicating damage to all fibers. On the contrary, the sensory function in all 3 fiber types was unchanged after MVD management. Conclusion： Among the 3 major surgical procedures tested, only MVD preserves sensory function in trigeminal system. CPTM is of quantitative nature on the evaluation of sensory functions of nerve fibers

The progress in diagnosis and treatment of trigeminal neuralgia

Trigeminal neuralgia(TN)is characterized by recurrent facial acupuncture like,electric shock like,burning like pain and other common clinical cranial nerve diseases in the trigeminal nerve distribution area.Around the world,people who are 40 or more are at risk.The incidence rate of TN of female is slightly higher than that of male and most of the affecting areas are on the right side unilaterally,which affects maxillary nerve and mandibular nerve,yet seldom ophthalmic nerve.Although controversy exists in the pathogenesis of TN,the most accepted theory is microvascular compression,which forces on the demyelination of the sensory axon of the trigeminal nerve root.Additionally,slight touch,conversation and chewing may cause intolerable pain.The diagnosis of TN mainly depends on clinical manifestation.The treatment mainly includes medicine,operation,and some supplementary methods.Among them,antiepileptics and tricyclic antidepressants are the first-line treatment.Surgical treatment is mainly used for patients with TN who have failed in drug treatment or have intolerable side effects.The methods of operation include destructive or non-destructive operation.Deep brain stimulation(DBS)and motor cortex stimulation(MCS)are new therapeutic techniques emerged recently.This method is expected to alleviate the refractory TN with poor drug control or ineffective conventional surgical treatment.At present,this method has not been approved for clinical treatment.Of course,more clinical data collection processes are in progress.

Inter-Observer Reliability of Fused Time-of-Flight MR Angiography and 3D Steady State Sequence versus 3D Contrast Enhanced Images in Evaluation of Neurovascular Compression

Purpose: Is to evaluate the accuracy of fused 3D time-of-flight (TOF) MR angiography and 3D Steady-State sequence (FIESTA) versus 3D contrast-enhanced T1 weighted images in evaluation of neurovascular compression via an inter-observer agreement protocol. Methods: Patients presented with trigeminal neuralgia, tinnitus, or facial hemispasm were examined using 3D-TOF-MRA, 3D-FIESTA, and 3D contrast-enhanced T1WI of the cerebellopontine angle to assess neurovascular compression. Two independent readers assessed the location, signal alteration, offending vascular structure, and grade of neurovascular compression using fused 3D-TOF-MRA and 3D-FIESTA versus contrast-enhanced T1 weighted images. The Kappa test for interobserver agreement was done. Results: The final study cohort consisted of 56 patients (42 females and 14 males) with a mean age of 38.25 ± 1.94. AICA was the offending vessel for 32 (57.1%) patients. The most common offending nerve was the trigeminal nerve in 26 patients, followed by facial/vestibulocochlear complex in 18 patients, and solely the 8th nerve in 12 patients. All three grades of compression were encountered in this study with percentages of 48.2% (27/56), 30.3% (17/56), and 21.4% (12/56) for grades I, II, III respectively. Fused TOF and steady-state images, and contrast-enhanced images showed perfect agreement for detection of the side of compression, the relation between nerve and vascular loop, offended neural segment, and offending vessel, while showing good agreement regarding the degree of compression. Conclusion: Fused TOF and steady-state images provide sufficient data to diagnose and grade microvascular compression syndromes comparable to contrast-enhanced images.