Petrosal Vein Involvement in Neurovascular Conflict in Trigeminal Neuralgia: Surgical Technique and Clinical Outcomes

BACKGROUND

Contact of the main stem of the petrosal vein (PV) to the nerve root is a rare cause of trigeminal neuralgia (TGN). The implication of the PV in relation with neurovascular contact (NVC) is not fully understood.

OBJECTIVE

To assess the operative procedures in microvascular decompression (MVD) in patients with PV involvement in the long-term.

METHODS

We retrospectively reviewed 34 cases (7.0%) in 485 consecutive MVDs for TGN, whose PV main stem had contact with the trigeminal nerve root (PV-NVC). PV-NVCs were divided into 2 groups: concomitant arterial contact or no concomitant arterial contact. Surgical techniques, outcomes, complications, and recurrence were assessed.

RESULTS

The anatomical relationship of the PV with the trigeminal nerve root was consistent with preoperative 3-dimensional imaging in all patients. Pain relief was obtained in most patients immediately after surgery (97.1%) by separating the PV from the nerve root. Postoperative facial numbness was noted in 9 patients (26.5%). Symptomatic venous infarctions occurred in 2 patients (5.9%). Recurrence of facial pain occurred in 3 patients (8.8%) with a median 48 mo follow-up period. Re-exploration surgery revealed adhesion being the cause of recurrence. The statistical analyses showed no difference in the surgical outcomes of the 2 groups.

CONCLUSION

Separating the PV from the nerve root contributes to pain relief in patients with PV conflict regardless of concomitant arteries. Preserving venous flow is crucial to avoid postoperative venous insufficiency.

Complication Rates During Endoscopic Microvascular Decompression Surgery Are Low With or Without Petrosal Vein Sacrifice

OBJECTIVE

Endoscopic-microvascular decompression (E-MVD) is a well-described treatment for trigeminal neuralgia (TGN), but there has been debate on the safety of intraoperative sacrifice of the petrosal vein (PV) due to concern for subsequent venous insufficiency. Our objective was to investigate the risk of PV sacrifice during E-MVD in TGN and subsequent postoperative complications and pain outcomes.

METHODS

5 five-year review yielded 201 patients who underwent MVD for TGN. PV sacrifice, vascular compressive anatomy, and postoperative complications attributable to venous insufficiency were analyzed. Preoperative and postoperative pain outcomes were analyzed.

RESULTS

PV was sacrificed in 118 of 201 (59%) of patients, with 43 of 201 (21%) patients undergoing partial sacrifice versus 75 of 201 (37%) with complete sacrifice. No cases of venous infarction, cerebellar swelling, or fatal complications were noted in either cohort. Non-neurologic complications occurred in 1.69% (2 of 118) of patients with PV sacrifice and 0% (0 of 83) of patients with PV preservation. Neurologic deficits (facial palsy, conductive hearing loss, gait instability, memory deficit) occurred in equal proportions in PV preservation and sacrifice groups (2.41% vs. 1.69%) Overall, 87.3% (145 of 166) patients reported their pain as "very much improved" or "much improved" at 1 month, and no difference between groups was identified.

CONCLUSIONS

This study did not find higher complication rates in patients undergoing petrosal vein sacrifice during E-MVD for trigeminal neuralgia. In this series where petrosal vein was sacrificed only 59% of the time, it appears to be a safe technique, but larger studies will be needed to determine true incidence of complications after PV sacrifice.

Traumatic Arteriovenous Fistula Between Extracranial Middle Meningeal Artery and Petrosal Vein

BACKGROUND

The incidence of traumatic arteriovenous fistula (TAVF) between the middle meningeal artery (MMA) and the petrosal vein (PV) is rare. Although TAVF has been reported involving the MMA several sinus and veins, this is the first incidence of a fistula involving the extracranial MMA and PV.

CASE DESCRIPTION

We present a 47-year-old male with sudden onset of weakness of his right limb and speech difficulty a few hours before admission to our facility. He had a 6-month history of mild traumatic head injury. Initial computed tomography revealed midbrain hemorrhage while digital subtraction angiography revealed a TAVF of the left MMA. Enhanced magnetic resonance imaging, however, revealed communication between the MMA and PV. We treated the patient with coil embolization via the transarterial route.

CONCLUSIONS

This is the first incidence of a fistula connecting the extracranial MMA and PV. We managed the patient with only coil embolization without any further neurologic deficits.

Superior Petrosal Vein Sacrifice During Microvascular Decompression: Perioperative Complication Rates and Comparison with Venous Preservation

OBJECTIVE

To investigate potential effect of sacrifice of the superior petrosal vein (SPV) on postoperative complications after microvascular decompression (MVD).

METHODS

Retrospective review of 98 consecutive patients undergoing MVD of cranial nerve V was performed. Frequency of division of the SPV during surgery was recorded, and postoperative complications and imaging were recorded and analyzed. In patients with complications, the specific anatomic variation of the superior petrosal venous complex was noted.

RESULTS

Of 98 patients undergoing MVD, 83 (84.7%) had sacrifice of the SPV at the time of surgery, 12 (12.2%) had the SPV preserved, and 3 (3.1%) were revision operations. Four patients (4.8%) had complications deemed to be attributable to venous insufficiency or congestion. These included sigmoid sinus thrombosis with coincident cerebellar hemorrhage, midbrain and pontine infarction, hemiparesis with midbrain and pontine edema, and facial paresis with ischemia in the middle cerebellar peduncle. None of the patients with preserved SPV were symptomatic or had imaging changes consistent with venous congestion.

CONCLUSIONS

Sacrifice of the SPV is often performed during MVD. This is associated with a complication rate that is significant in frequency and severity compared with preserving the vein. SPV sacrifice should be limited to cases where it is deemed absolutely necessary for successful cranial nerve decompression.

Safety of Superior Petrosal Vein Sacrifice During Microvascular Decompression of the Trigeminal Nerve

BACKGROUND

Microvascular decompression (MVD) is a safe and effective treatment for trigeminal neuralgia. Cerebellar venous infarction is a complication associated with surgical sacrifice of the superior petrosal vein (SPV). The SPV intervenes between the trigeminal nerve and the surgeon. Optimal exposure of the cisternal trigeminal nerve, particularly at the brainstem, can be achieved by sacrificing the SPV. We analyzed a cohort of 224 patients to determine the frequency of cerebellar venous infarction.

METHODS

Retrospective analysis of records and neuroradiology for patients undergoing trigeminal MVD at the Manchester Skull Base Unit between August 1st 2008 and July 31st 2015.

RESULTS

A total of 184 of 224 (82%) patients had coagulation and division of the main stem of the SPV. There were no cases of venous infarction. There was one case of mild, transient, cerebellar symptoms and signs, with no radiologic evidence of venous infarction. This patient had SPV sacrifice at surgery but also had postoperative thrombosis of the transverse sinus. Venous sinus thrombosis affected 5 of 184 (2.7%) patients. A total of 208 of 224 (93%) patients had a good outcome with improvement or resolution of their trigeminal neuralgia at 3 months.

CONCLUSIONS

The overall rate of venous complications in this study was 2.7%; however, we had no cases of venous infarction in 184 patients who had sacrifice of the SPV. The incidence of venous infarction associated with SPV obliteration during MVD surgery is therefore <0.5%. SPV sacrifice may be used where necessary to optimize visualization of the root entry zone and maximize the chance of effective decompression of the trigeminal nerve.

[Anatomy and management of superior petrosal vein in microvascular decompression for trigeminal neuralgia]

Objective: To investigate the characteristics of superior petrosal vein (SPV) and its influence on the surgical field in microvascular decompression (MVD) for trigeminal neuralgia (TN), and to analyze the effect of the surgical treatment of SPV on the surgical approach, indication and prognosis. Methods: The clinical data of 280 patients with trigeminal neuralgia between Jan. 2013 and Jun. 2016 were collected, including the trunks and the branches of SPV, intraoperative electrocoagulation status, the surgery outcome and complications. Results: The petrosal vein during the operation was fully preserved in 152 cases (54.29%). The SPV were completely sectioned in 25 cases (8.92%), while some branches of SPV were sectioned in 103 cases (36.79%). We found that SPV have 1 to 3 trunks, accounted for 67 cases (23.90%), 168 cases (60%), and 45 cases (16.10%), while the SPV with 1 to 4 branches accounted for 17 cases (6.07%), 112 cases (40%), 136 cases (48.57%), and 15 cases (5.36%). The SPV was identified as offending vessel in 17 cases (6.07%). One patient with cutoff SPV trunk encountered cerebellar infarction and recovered completely at 2 weeks after MVD by using intravenous medication. Conclusions: MVD is the recommended treatment method for PTN, mostly SPV is unnecessary to be sectioned completely and small branches of SPV could be sacrificed. Very few patients may develop cerebellar infarction or hematoma.

Management of different kinds of veins during microvascular decompression for trigeminal neuralgia: technique notes

OBJECTIVE

During microvascular decompression surgery for trigeminal neuralgia, surgeons will encounter various kinds of veins that block the approach to or compress the trigeminal nerve. The aim of this study was to present our experience in managing different kinds of veins.

METHODS

This was a retrospective study of 21 patients with trigeminal neuralgia, in whom one or more veins were encountered during surgery. The techniques used in treating 4 types of veins during microvascular decompression were assessed, and the surgical outcomes and operative complications were analysed.

RESULTS

For the first type, large veins blocking the approach towards the root entry zone (REZ) of the trigeminal nerve were bypassed via cerebellar fissure approach. Second, veins lying on the brainstem surface and compressing the REZ were detached using a gelatin-assisted dissecting technique and then interposed. Third, veins rising from the surface of the brainstem and crossing the cisternal portion of the trigeminal nerve were interposed. Fourth, intraneural veins, which were generally small, were coagulated and cut. In this series, there was no intentional sacrifice or unintentional rupture of large veins, and the sacrifice rate of medium and small veins was only 19.0%. Thirteen patients (61.9%) gained complete pain relief immediately after surgery (i.e. "excellent" result), while the remaining eight patients (38.1%) achieved "good" pain relief.

CONCLUSION

Different surgical techniques were used based on the different kinds of veins encountered. This allowed preservation of almost all the large veins. There were no serious complications postoperatively.

The Analysis of the Petrosal Vein to Prevent Venous Complications During the Anterior Transpetrosal Approach in the Resection of Petroclival Meningioma

BACKGROUND

The anterior transpetrosal approach (ATPA) has been used in the resection of petroclival meningioma (PCM) for more than 20 years. Although PCM sometimes involves the petrosal vein and its preservation has been an important issue, the precise risk of petrosal vein sacrifice and subsequent venous complications associated with the use of the ATPA in patients with PCM has not yet been elucidated.

METHODS

We used computed tomographic (CT) digital subtraction venography (DSV) in the retrospective analysis of the petrosal vein and its tributaries in patients with PCM before and after surgery. We also examined the incidence of postoperative venous complications in each of the patients.

RESULTS

The detection rate of the petrosal vein and some of its tributaries on CT-DSV in patients with PCM was significantly lower than that in controls. Preoperatively, CT-DSV detected the petrosal vein in 71.8% of patients with PCM. The detected petrosal veins were preserved after the operation in 64.3% of these patients. No venous complications involving petrosal vein were observed in any of the patients. Anastomosis between the petrosal vein and the basal vein via the pontotrigeminal vein was found to be significantly more developed in the patients with PCM compared with the controls.

CONCLUSIONS

Our study demonstrated that the ATPA could be performed safely on patients with PCM from the viewpoint of venous preservation. Preoperative CT-DSV is important for assessing the petrosal vein and its tributaries to facilitate a safer operation.

Anterior Transpetrosal Approach Combined with Partial Posterior Petrosectomy for Petroclival Meningiomas with Posterior Extension

BACKGROUND

An anterior transpetrosal approach (ATPA) is suitable for treating upper petroclival lesions. However, the limit of the ATPA is reached when the tumor extends posterolaterally over the internal auditory canal (IAC) along the petrous edge. In such cases, ligation of the posterior part of the superior petrosal sinus (SPS) is necessary. To overcome this limitation, we combined the ATPA with a partial posterior petrosectomy in 8 patients who had petroclival meningiomas extending posterolaterally over the IAC.

METHODS

We resected only the Trautmann triangle in addition to the Kawase triangle to secure the space to ligate the posterior portion of the SPS. Because the tympanic cavity and bony labyrinth of the ear were not exposed, we were able to preserve hearing function and lower the risk of cerebrospinal fluid leakage. Furthermore, this approach enables easy ligation of the SPS and the tentorium posterior to the tumor attachment. This combined technique also allows visualization of the petrosal vein, which is important for surgery of the posterior fossa.

RESULTS

Total and near-total tumor removal was achieved in 6 patients (75%) with no permanent complications and no cerebrospinal fluid leakage. Postoperative hearing impairment was not found in any of the patients who underwent this surgery.

CONCLUSIONS

The ATPA combined with partial posterior petrosectomy is an effective method for removal of complicated petroclival meningiomas that extend posterolaterally over the IAC along the petrous edge.