Shiting Li

A clinical analysis on microvascular decompression surgery in a series of 3000 cases.

OBJECTIVE Despite the microvascular decompression (MVD) has become a definitive treatment for trigeminal neuralgia (TN) and hemifacial spasm (HFS), not all of the patients have been cured completely so far and this sort of operation is still with risk because of the critical operative area. In order to refine this surgery, we investigated thousands MVDs. METHODS Among 3000 consecutive cases of MVDs have been performed in our department, 2601 were those with typical TN or HFS, who were then enrolled in this investigation. They were retrospectively analyzed with emphasis on the correlation between surgical findings and postoperative outcomes. The differences between TN and HFS cases were compared. The strategy of each surgical process of MVD was addressed. RESULTS Postoperatively, the pain free or spasm cease occurred immediately in 88.3%. The symptoms improved at some degree in 7.2%. The symptoms unimproved at all in 4.5%. Most of those with poor outcome underwent a redo MVD in the following days. Eventually, their symptoms were then improved in 98.7% of the reoperative patients. The majority reason of the failed surgery was that the neurovascular conflict located beyond REZ or the offending veins were missed for TN, while the exact offending artery (arteriole) was missed for HFS as it located far more medially than expected. CONCLUSION A prompt recognition of the conflict site leads to a successful MVD. To facilitate the approach, the craniotomy should be lateral enough to the sigmoid sinus. The whole intracranial nerve root should be examined and veins or arterioles should not be ignored. For TN, all the vessels contacting the nerve should be detached. For HFS, the exposure should be medial enough to the pontomedullary sulcus.

The value of abnormal muscle response monitoring during microvascular decompression surgery for hemifacial spasm

BACKGROUND AND OBJECTIVES Abnormal muscle response (AMR) to the electrical stimulation of a branch of facial nerve is a specific electrophysiological feature of primary hemifacial spasm (HFS). The aim of this study was to evaluate the value of AMR monitoring during microvascular decompression surgery (MVD), and the correlation between the AMR changes and the clinical outcomes. METHODS This study included 241 cases of MVDs. Intraoperative AMR monitoring was performed for each subject. The patients were divided into two groups based on whether the AMR-disappeared or not following decompression of the facial nerve. RESULTS Postoperatively, 229 (95.0%) patients were relieved from the spasm, 215 (93.9%) occurred in the AMR-disappeared group, 14 (6.1%) in the non-AMR-disappeared group. The correlation between intraoperative AMR abolition and HFS relief was statistically significant. CONCLUSIONS Intraoperative AMR monitoring was an effective assistant for a successful MVD for the patient with HFS. It is worth being routinely employed during the operation.

Clinical features and surgical treatment of trigeminal neuralgia caused solely by venous compression

PurposeTo summarize our experience and lessons of microvascular decompression surgery for trigeminal neuralgia caused solely by venous compression.MethodsFifteen patients with idiopathic trigeminal neuralgia caused by venous compression only underwent microvascular decompression. The entire course of the trigeminal root was explored thoroughly; and coagulating and cutting techniques were preferred in decompressing the culprit veins. Their clinical features, outcomes and operative complications were analyzed.ResultsThe compressing veins included the transverse pontine vein in five cases (33.3%), the transverse pontine vein and the vein of middle cerebellar peduncle in one (6.7%), the transverse pontine vein and the vein of cerebellopontine fissure in one (6.7%), the superior petrosal vein in three (20%), the pontotrigeminal vein in one (6.7%), the vein of the cerebellopontine fissure in two (13.3%), and the plexus venosus or venule in two (13.3%). After microvascular decompression, 11 cases (73.3%) had “excellent” or “good” pain relief. Four cases (26.7%) failed the first surgery; and two of them underwent re-operation and got “excellent” pain relief. Postoperative facial numbness appeared in four cases, due to injury to trigeminal nerve when coagulation.ConclusionThe transverse pontine vein is the most common offending vein. For this type of trigeminal neuralgia, coagulating and cutting techniques are preferred in decompressing the culprit veins. The entire course of the trigeminal root should be explored and decompressed. Following these principles, excellent or good pain relief could be achieved in most cases; and recurrence is rare. However, sometimes injury to the nerve is unavoidable when coagulating the culprit vein.

Is entire nerve root decompression necessary for hemifacial spasm

OBJECTIVE The root exit zone (REZ) of the seventh cranial nerve has been the target of microvascular decompression surgery (MVD) while searching the neurovascular conflict for treatment of hemifacial spasm for long time. Recently, increasing cases regarding the offending vessel beyond the REZ have been reported. To verify whether a thorough dissection of the nerve may give rise to a better postoperative result without enhancing complications, we conducted a parallel investigation. PATIENTS AND METHODS 112 Connective entire-nerve-exposed MVDs were performed and compared to 186 REZ-exposed MVDs performed by the same group of surgeons in 2009. The surgical findings, postoperative outcomes and complications as well as microscopic operating time were examined. RESULTS Immediately after the surgery, the outcomes were excellent in 98.2%, good in 1.8% and poor in 0% in the entire-nerve-exposed group, compared to excellent in 92.5%, good in 1.6% and poor in 5.9% in the REZ-exposed group. The difference of outcomes between the two groups were statistically significant (χ(2)=4.6845, P=0.0304), but not the complications and microscopic operating time. Nine of the 11 poor-outcome patients from the REZ-exposed group were then reoperated on within a few days, and their symptoms disappeared in eight patients. The main reason for the failed surgeries was that the offending vessels beyond REZ were missed. CONCLUSIONS These findings suggested that the entire-root-decompression technique is recommended while performing MVDs in patients with hemifacial spasm.

Management of petrosal veins during microvascular decompression for trigeminal neuralgia.

Abstract Objective: Venous compression might be the main cause of incomplete decompression and symptom recurrence after microvascular decompression (MVD) in patients with trigeminal neuralgia. Although it can be killed in most cases, cutting the vein sometimes has the potential risk arising from venous congestion. To maneuver the vein safely, we introduced a temporary occlusion test of the vein. Methods: Among 407 consecutive MVD cases, 48 (11.8%) offending and 157 block veins were encountered. The vein was cut directly in 147 (71.7%). Owing to the potential risk following killing of the vein, 58 (28.3%) patients underwent venous occlusion test with neurophysiologic monitoring during the operation. The temporal occlusion should be ceased immediately as soon as any changes in brainstem auditory evoked potential (BAEP) or trigeminal evoked potential (TEP) wave figuration turn up; otherwise, it would last for 15 minutes. Results: The occlusion test was negative in 53 (91.4%), while positive in five patients (8.6%). According to the results, we cut the vein in test-negative patients, which made the operation easy and offered a satisfactory decompression. Among the five positive cases, the vein was finally saved in two and cut in three cases. Yet, all the three patients developed a severe ipsilateral cerebellar edema and brainstem shift after the vein was sacrificed. Despite those patients were reoperated on immediately for posterior fossa decompression, they remained equilibrium disorder with numbness in ipsilateral face and mind hemiparesis in contralateral extremities post-operatively. The residual two patients had an incomplete pain relief. Conclusion: This venous occlusion test could help the surgeon in making a right decision before manipulation of the petrosal veins during MVD.

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

Background and objectivesMicrovascular 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.MethodsThirteen 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.ResultsAll 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.ConclusionsOur 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 decompressions in patients with coexistent hemifacial spasm and trigeminal neuralgia.

BACKGROUND:Although microvascular decompression (MVD) is widely accepted as the effective therapy for hemifacial spasm (HFS) or trigeminal neuralgia (TN), the surgical treatment of coexistent HFS and TN in an individual is seldom addressed. OBJECTIVE:To discuss the operative strategy of MVD for both the hemifacial and trigeminal nerves. METHODS:Nine consecutive cases of coexistent HFS and TN caused by neurovascular confliction in the same side were studied. Except for one, the patients suffered from HFS followed by ipsilateral TN. All patients underwent MVD and were followed up for 3 to 30 months. Each surgery was analyzed retrospectively. RESULTS:Intraoperatively, a looped vertebral artery (VA) shifted to the suffered side was found in 8 patients. The VA was regarded as the direct or indirect offending artery. After MVDs, the spasm ceased immediately in 6 patients; the other 3 patients had delayed relief within 3 months. The pain disappeared immediately in 7 of 9 patients. One patient felt relief after a week, and 1 had pain but improved slightly. No recurrence or complication was found. CONCLUSION:A shifted VA loop may account for this tic convulsif syndrome. MVD is a reasonable and effective therapy with a high cure rate for the disease. The key to the surgery is to move the VA proximally. The dissection should be performed rostrally starting from the caudal cranial nerves.

Microvascular decompression surgery: surgical principles and technical nuances based on 4000 cases

Abstract Background: As an etiological treatment of trigeminal neuralgia (TN) and hemifacial spasm (HFS), microvascular decompression (MVD) has been popularized around the world. However, as a functional operation in the cerebellopontine angle (CPA), this process can be risky and the postoperative outcomes might not be good enough sometimes. Objective: In order to obtain a better result with less complication, this surgery should be further addressed. Methods: With experience of more than 4000 MVDs, we have gained knowledge about the operative technique. Through abundant intraoperative photos, each step of the procedure was demonstrated in detail and the surgical strategy was focused. Results: The principle of MVD is to separate the nerve-vessel confliction rather than isolate it with prostheses. A prompt identification of the conflict site is important, which hinges on a good exposure. A satisfactory working space can be established by an appropriate positioning of the patients head and a proper craniectomy as well as a rational approach. A sharp dissection of arachnoids leads to a maximal visualization of the entire intracranial course of the nerve root. All the vessels contacting the trigeminal or facial nerve should be treated. Intraoperative electrophysiological mentoring is helpful to distinguish the offending artery for hemifacial cases. Conclusion: MVD is an effective treatment for the patient with TN or HFS. Immediate relief can be achieved by an experienced neurosurgeon with good knowledge of regional anatomy. A safe surgery is the tenet of MVD, and accordingly, no single step of the procedure should be ignored.

Effectiveness and safety of microvascular decompression surgery for treatment of trigeminal neuralgia: a systematic review.

Abstract Microvascular decompression has been now accepted worldwide as a reasonable treatment for trigeminal neuralgia, yet, as a functional operation in the cerebellopontine angle, this process may be risky and the postoperative outcomes might not be good enough sometimes. To assess the effectiveness and safety of microvascular decompression for treatment of trigeminal neuralgia, we conducted a systematic review. Using the keywords “trigeminal neuralgia”, “microvascular decompression”, or “neurovascular conflict”, manuscripts published in English-language journals and indexed in PubMed between January 1, 2000 and June 1, 2013 on the treatment of trigeminal neuralgia (TN) with microvascular decompression were considered for this study. The success and complications were analyzed. The success in this investigation was defined as complete pain free. Continuous outcomes were summarized using means or medians, and dichotomous outcomes were presented as percentage associated with 95% confidence interval. Twenty-six papers with 6,847 patients were finally enrolled in this review. Among them, the male-to-female ratio was 1:1.4, the left-to-right ratio was 1:1.6, and the pain was located in the innervation of V3 and/or V2 in most of the cases with only 2.3% (0.1–4.7) of V1 exclusively. The average age at surgery was 60.9 years (52.5–64.1) with TN symptoms duration of 24.7 months (6.1–42.1) before microvascular decompression (MVD). Operative findings confirmed the superior cerebellar artery, anterior inferior cerebellar artery, posterior inferior cerebellar artery, and multiple vascular contacts (including veins) as the most common sources of nerve compression. The average follow-up duration was 35.8 months (26.2–56.6). The success rate was 83.5% (79.6–89.1). Complications included incisional infection in 1.3% (0.1–2.5), facial palsy 2.9% (0.5–6.2), facial numbness 9.1% (1.3–19.6), cerebrospinal fluid leak 1.6% (0.7–2.5), and hearing deficit 1.9% (0.2–3.9). The postoperative mortality was 0.1% (0.02–0.2). Accordingly, MVD is the most effective treatment for patients with trigeminal neuralgia. An immediate pain free can be achieved by an experienced neurosurgeon with good knowledge of the regional anatomy. To avoid complications, each single step of the process cannot be overemphasized.

The role of autonomic nervous system in the pathophysiology of hemifacial spasm.

Abstract Objectives: Despite the vascular compression of the seventh cranial nerve has been verified by the microvascular decompression surgery as the cause of hemifacial spasm (HFS), the mechanism of the disease is still unknown. We believe that the autonomic nervous system in adventitia of the offending artery may contribute to the HFS. To prove our hypothesis, we performed an experiment in SD rats. Methods: Moller’s HFS model was adopted and the abnormal muscle response (AMR) wave was electrophysiologically monitored. With randomization, some HFS rats underwent exclusion of the offending artery or removal of the ipsilateral superior cervical ganglion. Some HFS rats with negative AMR following exclusion of the offending artery were dripped with norepinephrine onto the neurovascular conflict site. Results: With exclusion of the offending artery, AMR disappeared in 14 (70%) of the 20 HFS rats, while in three (30%) of the 10 from sham operation group (P<0·05). With ganglionectomy, AMR disappeared in 12 (75%) of the 16 HFS rats, while in two (25%) of the eight from the sham operation group (P<0·05). With norepinephrine drip, AMR reappeared in four (67%) of the six from those offending-artery-excluded HFS rats, while in zero of the six from normal-saline-dripped group (P<0·05). Discussion: The neurotransmitter releasing from the autonomic nervous endings in the worn adventitia of the offending artery may induce an ectopia action potential in those demyelinated facial nerve fibers expanding to the neuromuscular conjunction and trigger an attack of HFS.