Infectious hematopoietic necrosis virus N protein suppresses fish IFN1 production by targeting the MITA.

Interferon (IFN) is a vital antiviral factor in host in the early stages after the viral invasion. Meanwhile, viruses have to survive by taking advantage of the cellular machinery and complete their replication. As a result, viruses evolved several immune escape mechanisms to inhibit host IFN expression. However, the mechanisms used to escape the host's IFN system are still unclear for infectious hematopoietic necrosis virus (IHNV). In this study, we report that the N protein of IHNV inhibits IFN1 production in rainbow trout by degrading the MITA. Firstly, the upregulation of IFN1 promoter activity stimulated by poly I:C was suppressed by IHNV infection. Consistent with this result, the overexpression of the N protein of IHNV blocked the IFN1 transcription that was activated by poly I:C and MITA. Secondly, MITA was remarkably decreased by the overexpression of N protein at the protein level. Further analysis demonstrated that the N protein targeted MITA and promoted the ubiquitination of MITA. Taken together, these data suggested that the production of rainbow trout IFN1 could be suppressed by the N protein of IHNV via degrading MITA.

Via-cerebellar-fissures approach for microvascular decompression of trigeminal nerve.

Although the infratentorial superior-lateral cerebellar approach has been traditionally chosen for exposure of the V cranial nerve root in the process of microvascular decompression for treatment of trigeminal neuralgia, those petrosal veins often block this surgical corridor. To detour these petrosal veins, we require a new approach. We provide a via-cerebellar-fissures approach to expose well the trigeminal nerve. With microscopy, cerebrospinal fluid was drained sufficiently to relax the cerebellum. Caudally to petrosal veins, the dissection was started from the cerebellar fissures. With the arachnoid membranes around the petrosal fissure and superior cerebellopontine fissures being opened thoroughly, the root entry zone of V nerve was visualized directly. This new approach was used in 106 patients. Among them, the block veins were encountered in 17 (16.0%). Among the 17 vein-blocked cases, 1 or 2 branches of the veins were finally cut in 2 (1.9%). The postoperative relief rate was 95.3% without complications. This via-cerebellar-fissures approach may access the root entry zone of the V cranial nerve without killing those petrosal veins, which is worth to be recommended and popularized.

Microvascular decompression on patients with trigeminal neuralgia caused by ectatic vertebrobasilar artery complex: technique notes.

BACKGROUND: Due to its anatomical features, the vertebrobasilar artery complex (VBA) seldom contributes to the neurovascular conflict in patient with trigeminal neuralgia (TN). However, once it offends the trigeminal root, this large artery is really difficult to manipulate during microvascular decompression (MVD) surgery. Therefore, the surgical strategy for such cases needs to be detailed in order to obtain a satisfactory outcome. METHODS: From 2009 through 2011, 475 consecutive TN patients underwent MVDs in our department. Among them, ten were found in which an ipsilateral deviating ectatic vertebrobasilar artery complex (VBA) offended the trigeminal nerve. Those cases were focused on in this study and each operation was analyzed retrospectively. RESULTS: During the operation, the vertebral artery was regarded as the direct culprit in six (60 %) patients, while the basilar artery in four (40 %). As companions, some smaller vessels were also observed to be close to the nerve, including the superior cerebellar artery (SCA) in five, veins in two and anterior inferior cerebellar artery (AICA) in two. The neurovascular conflict was discovered in the cisternal segment of the trigeminal root in eight, while in the root entry zone (REZ) in two. In six out of the ten cases, the affected nerves were demonstrated to be squeezed towards the tentorium by the ectatic VBA. Postoperatively, the symptom of pain totally disappeared immediately in eight (80 %) patients, while it was relieved apparently in two (20 %). During the follow-up period of 3-30 months, no recurrence or complication was found, except for one patient who had numbness of the face. CONCLUSION: With a proper strategy, MVD is probably the most effective therapy for the TN cases caused by ectatic vertebrobasilar artery complex. The substance of the surgery is to withdraw the proximal vertebral artery caudally via a lateroinferior cerebellar approach.

Microvascular decompression for hemifacial spasm.

OBJECTIVE: Although microvascular decompression (MVD) has been accepted as effective therapy for hemifacial spasm, failed surgery has been reported frequently. For a sophisticated neurosurgeon, an apparent offending artery is seldom missed. However, it is still an embarrassed situation when the neurovascular conflict site could not be approached. METHODS: Clinical data were collected from consecutive 211 MVDs in 2010. Intraoperative abnormal muscle response was recorded. Among them, the neurovascular conflict was not finally discovered in 3 patients, whom were then focused on. All patients were followed up for 6 to 15 months. RESULTS: In 17 of the 211 MVDs, the cerebellum was hard to be retracted because of adhesions. After careful dissection, a working space was finally created in the cerebellopontine angle. However, there still were 3 cases, whose neurovascular conflict site was unable to be discovered at last because of a branch of an artery embedded in the petrous bone and made the cerebellum unmovable. With navigation of real-time abnormal muscle response, the offending artery was moved away eventually even without exposing the conflict site. Postoperatively, all the patients were completely spasm-free immediately. No recurrence was noticed in the last follow-up period. CONCLUSIONS: The most important thing for a successful MVD operation is to remove the offending artery off the nerve. However, if the conflict site failed to be approached after endeavors, a successful MVD can still be achieved by relocating the offending artery with the guidance of real-time electromyography even without visualization of the confliction.

An analysis of failed microvascular decompression in patients with hemifacial spasm: focused on the early reoperative findings.

BACKGROUND: Although the microvascular decompression (MVD) has become a definitive treatment for the primary hemifacial spasm (HFS), there still are some failed cases. To obtain a satisfactory postoperative outcome, those failure cases of MVD need to be analyzed. METHOD: Between January and October 2009, 393 patients with primary HFS underwent MVD. Postoperatively, 375 presented complete spasm-free, 7 improved apparently, and 11 without any improvement at all. A reoperation was performed in 9 of the 11 patients who had poor outcome within 5 days. Those redo MVD cases were reviewed. FINDINGS: After the reoperation, the symptom of those patients all disappeared immediately. Therefore, the final outcomes were excellent in 97.7%, good in 1.8%, and poor in 0.5%. Up to the 1 year follow-up period, neither recurrence nor change was found. For the two patients without reoperation, their symptoms remained. The previous surgery was a failure due to insufficient decompression in two and conflict missed in seven. CONCLUSIONS: A successful MVD operation is attributable to a thorough exploration of the entire nerve course. An early relief should become the ambition of the operator while performing MVD.

Role of arterioles in management of microvascular decompression in patients with hemifacial spasm.

Although microvascular decompression (MVD) is accepted as an effective therapy for hemifacial spasm (HFS), some operations fail. While performing MVD, many surgeons focus on the large arteries but ignore the arterioles. Failure to identify involved arterioles may account for unsuccessful MVD. We aimed to refine the MVD surgery and improve post-operative outcomes by proper management of involved arterioles. Clinical data were collected from 69 consecutive patients who underwent MVD. Intraoperative electromyography (EMG) was employed for each MVD. Each operation was reviewed with a focus on the involved arterioles. All patients were followed up for between nine and 12 months. An abnormal muscle response (AMR) wave was identified by EMG in all patients before decompression, but vanished in most patients as soon as the involved arteries were removed from the cranial nerve (CN). However, in nine of 69 patients, the AMR did not immediately disappear. Further dissection and exploration of the entire CN VII identified an arteriole in contact with, or in some patients embedded in, the nerve. Once the arteriole was isolated from the CN, the AMR disappeared. After surgery, spasms ceased in all patients and no recurrence was found up to the one-year follow-up. To achieve a positive post-operative outcome, exploration of the entire CN VII is necessary, with a focus on the small arterioles. AMR can be a good adjuvant to identify the involved arterioles.

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.

Correlation between idiopathic hemifacial spasm and the MRI characteristics of the vertebral artery.

We studied the correlation between the anatomy of the vertebral artery (VA) and the symptoms of primary hemifacial spasm (HFS). Between June and October 2009, 88 patients with primary HFS underwent a preoperative MRI and subsequent microvascular decompression surgery. Each patient's VA was categorized into one of three types according to their MRI findings. In Type I, the bilateral VA that join to form the basilar artery in the mid line appear symmetrical. In Type II, the VA distribute asymmetrically and deviate to one side (Type IIa deviate to the symptomatic side; Type IIb to the contralateral side). In Type III, both VA occur on the same side (Type IIIa occur on the symptomatic side; Type IIIb on the contralateral side). The correlation between deviation of the VA and the symptomatic side of primary HFS was analyzed statistically. Of the 88 patients, the number of patients with each type of VA, as identified by three-dimensional time-of-flight MRI was: Type I=3, Type II=48 (Type IIa=40, Type IIb=8) and Type III=37 (Type IIIa=36, Type IIIb=1). The anatomical characteristics of the VA (lateral deviation) were significantly related to the symptomatic side of the primary HFS (chi-squared [χ(2)]=102.14; p<0.01; relative risk=8.44). The likelihood that the VA deviated to the symptomatic side was 86.4%, while the likelihood of deviation to the asymptomatic side was 10.2%. Thus, anatomical variation of the VA (lateral deviation) is one of the risk factors for primary HFS.

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.

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.