Individual variations of the superior petrosal vein complex and their microsurgical relevance in 50 cases of trigeminal microvascular decompression

Intraoperative application of indocyanine green and temporary venous occlusion test to assess collateral flow during microvascular decompression for venous-related trigeminal neuralgia: illustrative case

BACKGROUND

In microvascular decompression (MVD) for vein-related trigeminal neuralgia (TN), determining whether transection of the offending vein is safe can be challenging. Here, the authors present a case of vein-related TN successfully treated by sacrificing the offending vein on the basis of findings from indocyanine green (ICG) video angiography and a temporary venous occlusion test to assess the collateral flow of the offending vessel.

OBSERVATIONS

A 43-year-old man presented with TN, which had failed to respond to previous medical therapy. Gadolinium-enhanced magnetic resonance imaging (MRI) revealed that the transverse or superior petrosal vein was the offending vein. The patient underwent MVD. Because the transposition of the offending vein was anatomically challenging, a temporary vein occlusion test was performed using ICG video angiography. During and after temporary occlusion, bidirectional flow in the offending vein was observed, suggesting collateral flow even after vein occlusion. On the basis of these findings, the offending vein was transected, resulting in relief from pain without any complications. Postoperative MRI revealed no new lesions in the brainstem or the cerebellar hemisphere. The patient has been free from neuralgia for 6 months.

LESSONS

The temporary vein occlusion test under ICG video angiography was useful for evaluating collateral flow in the offending vein in TN.

Preoperative assessment of the individual anatomy of the superior petrosal vein complex using balanced fast field echo magnetic resonance imaging

BACKGROUND

Here, we sought to examine the validity and reproducibility of balanced fast field echo (bFFE) for assessing superior petrosal vein (SPV) complex (SPVC) anatomy.

METHODS

Preoperative bFFE or equivalent scans and operative videos were studied and directly compared with regard to the individual anatomical features of SPVCs and their relation to the operative field. The anatomical details of the bFFE findings of the non-operated side (group 2) of all 50 patients were then reviewed, including the presence of petrosal-galenic anastomosis, and finally compared to the operated SPVCs (group 1).

RESULTS

A complete correlation between bFFE and intraoperative findings was observed in 62% of cases and had a significant correlation with 3 Tesla magnet strength and higher pixel bandwidth (rbis = - 0.47; p = 0.005). The sensitivity and specificity of bFFE magnetic resonance imaging were 93.7 and 95.2%, respectively, for detecting an SPV disturbing the operative field, and 97.3% and 95% for a disturbing tributary, respectively. Each group had 50 SPVCs, with a total of 70 and 64 SPVs, 10 and 11 general SPVC configurations, as well as 29 and 28 different individual anatomical variations in groups 1 and 2, respectively. Both groups had 1-3 SPVs with a similar distribution of frequencies [Chi-square (4) = 27.56; p = 0.0145 (Fisher's exact test)]. The similarity of the general configurations was not statistically significant. The same four predominant configurations constituted 80% of the SPVCs in each group. The vein of the cerebellopontine fissure was most frequently found in 86% and 88% of cases, and a petrosal-galenic anastomosis was seen in 38% and 40% of groups 1 and 2, respectively.

CONCLUSIONS

Individual SPVC variations are extensive. Good quality bFFE or equivalents are feasible for preoperative SPVC assessments. However, methods improving vascular visualization are recommended.

Multiple Vessel Compression of the Trigeminal Nerve Is Associated With Worse Outcomes in Trigeminal Neuralgia After Microvascular Decompression

BACKGROUND

Whether the total number of compressive vessels in trigeminal neuralgia (TN) affects outcomes after microvascular decompression (MVD) is unknown.

OBJECTIVE

To investigate whether the number of compressive vessels is associated with outcomes after MVD.

METHODS

We retrospectively reviewed all patients with TN who underwent MVDs at our institution from 2007 to 2020. The number and identity of compressive vessels on the trigeminal nerve were recorded. Preoperative and postoperative pain and numbness Barrow Neurological Institute scores were compared. Factors associated with pain recurrence were assessed using survival analyses and multivariate regressions.

RESULTS

We identified 496 patients with a single vessel and 381 patients with multiple vessels compressing the trigeminal nerve. Compared with patients with a single compressive vessel, patients with multiple sources of compression exhibited increased Barrow Neurological Institute pain scores preoperatively ( P = .01). In addition, pain recurrence was more frequent ( P < .001) and occurred after a significantly shorter pain-free duration ( P < .001) for the multiple compression group. Using multivariate ordinal regression, a greater number of arteries ( P = .03) and veins ( P = .03) were both significantly associated with higher pain scores at final follow-up. Furthermore, the number of arteries ( P = .01) and of veins ( P = .01) was significantly associated with a higher risk for pain recurrence.

CONCLUSION

TN patients with a single compressive vessel exhibited better pain outcomes after an MVD. Patients with multiple compressive vessels exhibited higher pain scores preoperatively and incurred a higher risk for pain recurrence, which occurred after a shorter pain-free interval compared with the single compression cohort.

Venous Flow Conversion Technique for Sacrificing the Superior Petrosal Vein During Microvascular Decompression for Trigeminal Neuralgia

BACKGROUND

Microvascular decompression for trigeminal neuralgia (TN) may require sacrifice of the superior petrosal vein (SPV), with potential risks of ischemia and hemorrhagic complications due to impaired venous return.

OBJECTIVE

To investigate methods for safely sacrificing the SPV.

METHODS

We retrospectively reviewed 21 cases in 346 consecutive microvascular decompression surgeries for TN. They were intraoperatively identified as SPV and its tributaries being the offending vessels causing TN and were intentionally sacrificed.

RESULTS

The transverse pontine vein (TPV) was sacrificed in 10 patients. The main trunk of the SPV was sacrificed using the TPV as a collateral flow pathway in 10 patients. No complications occurred related to impaired venous return.

CONCLUSION

The venous flow conversion technique can be applied to safely sacrificing the SPV and its tributaries with the TPV acting as a collateral blood flow pathway to prevent postoperative impaired venous return.

Cadaveric findings of a duplicated superior petrosal sinus

Knowledge of the intracranial dural venous sinuses and their variations is important in the diagnosis and management of many cranial pathologies. We report a unique duplication of the right-sided superior petrosal sinus identified during routine dissection of the skull base.. Lateral to this sinus, a separate and more curvilinear superior petrosal sinus left the normally positioned superior petrosal sinus and traveled posteriorly near the foramen spinosum and then turned medially to drain into the normally positioned superior petrosal sinus. Anteriorly, the two sinuses joined together and drained into the cavernous sinus. Posteriorly, the laterally positioned sinus drained into the normally positioned sinus which then traveled in normal fashion along the petrous ridge to end in the transverse sinus. To our knowledge, such a duplication has not been previously reported in the extant medical literature.

Intraoperative Findings of Inferior Petrosal Vein During Microvascular Decompression for Hemifacial Spasm: A Single-Surgeon Experience

Objective

This study aims to evaluate the impact of the inferior petrosal veins (IPVs) on operational exploration and to analyze related anatomic features.

Methods

A total of 317 patients were retrospectively studied. Surgical outcomes and postoperative complications were analyzed, and patients were divided into two groups according to whether the IPV was sacrificed or preserved. The diameter of the IPV was also recorded during operation. Furthermore, the position where the IPV drained into the jugular bulb was recorded in each patient, and the influence of different injection points on the operation was analyzed.

Results

IPVs were conclusively identified in 242/317 (76.3%) of patients, with 110/242 (45.5%) of patients categorized as “IPV sacrifice” versus 132/242 (54.5%) categorized as “IPV preservation.” IPV diameter was observed to be <0.5 mm in 58 cases (23.9%), 0.5 mm–1.0 mm (≥0.5 mm and ≤1.0 mm) in 145 cases (59.9%), and >1 mm in 39 cases (16.2%). The position of IPV drainage into the jugular bulb was at the level of the accessory nerve in 163 cases (67.3%), the level of the vagus nerve in 42 cases (17.4%), and the level of the glossopharyngeal nerve or above in 37 cases (15.3%). The diameters of IPV in the sacrifice group were mainly less than 1 mm (94.5% vs. 75%, P < 0.01), and the cases with draining points near the glossopharyngeal nerve were more than that in the preservation group (27.3% vs. 5.3%, P < 0.01).

Conclusion

IPV is an obstructive structure in MVD for HFS, with considerable variations in diameters and draining points. IPV near the glossopharyngeal nerve significantly impacts surgical exposure and is often sacrificed for a better view of the operation field. Meanwhile, it is feasible to maintain IPVs with a diameter >1 mm.

Prevention of Superior Petrosal Vein Injury during Microvascular Decompression for Trigeminal Neuralgia: Operative Nuances

Background The superior petrosal vein (SPV) often obscures the surgical field or bleeds during microvascular decompression (MVD) for the treatment of trigeminal neuralgia. Although SPV sacrifice has been proposed, it is associated with multiple complications. We have performed more than 4,500 MVDs, including approximately 400 cases involving trigeminal neuralgia. We aimed to describe our operative technique and nuances to avoid SPV injury.

Methods We have provided a detailed description of our institutional protocol, including the anesthesia technique, neurophysiologic monitoring, patient positioning, surgical approach, and SPV management. The surgical outcomes and treatment-related complications were retrospectively analyzed.

Results No SPVs were sacrificed intentionally or accidentally during our MVD protocol for trigeminal neuralgia. In the 344 operations performed during 2006 to 2020, 269 (78.2%) patients did not require medication postoperatively, 58 (16.9%) tolerated the procedure with adequate medication, and 17 (4.9%) did not respond to MVD. Postoperatively, 35 (10.2%), 1 (0.3%), and 0 patients showed permanent trigeminal, facial, or vestibulocochlear nerve dysfunction, respectively. Wound infection occurred in five (1.5%) patients, while cerebrospinal fluid leaks occurred in three (0.9%) patients. Hemorrhagic complications appeared in four (1.2%) patients but these were unrelated to SPV injury. No surgery-related mortalities were reported.

Conclusion MVD for the treatment of trigeminal neuralgia can be achieved safely without sacrificing the SPV. A key step is positioning the patient's vertex at a 10-degree elevation from the floor, which can ease venous return and loosen the SPV, making it less fragile to manipulation and providing a wider surgical corridor.

Vein-related Trigeminal Neuralgia: How to Determine the Treatment Method of the Causative Vein: A Technical Note

Trigeminal neuralgia (TN) is often caused by various vein forms. Herein, we report two cases of vein-related TN. In the first case, the vein of the cerebellopontine fissure (VCPF), along with the thickened surrounding arachnoid, clung to the trigeminal nerve. As the perfusion range of this vein was expected to be wide and its injury might cause extensive venous infarction, the anchor between the trigeminal nerve and the vein was carefully dissected and the vein was successfully transposed. In the second case, the involvement of the vein of the middle cerebellar peduncle (VMCP), which penetrates the nerve bundle of the trigeminal nerve, was suspected. Because vein transposition was impossible, the vein was transected at the nerve penetration site after confirming that there was sufficient collateral venous outflow. The superior petrosal vein and its tributaries are the primary causative veins of vein-related TN, and their contact patterns are infinite. Moreover, their perfusion range and the presence or absence of collateral venous outflow vary from case to case. Therefore, it is necessary to judge the perfusion range as well as collateral venous outflow based on preoperative images and intraoperative findings and to determine the appropriate treatment method for each case.

Deadly complication of sacrificing superior petrosal vein during cerebellopontine angle tumor resection: A case report and literature review

Background:

Tumors of the cerebellopontine angle (CPA) are challenging to resect and have been proven difficult for neurosurgeons to manage optimally. Superior petrosal vein complex (SPVC) as the main drainage system and close proximity to CPA could be an obstacle during operation. There is an incidence ranging from 55% to 84% of injury to one part of the SPVC during CPA tumor surgery.

Case Description:

We report a case of 65-year-old woman with CPA tumor, who complained of unilateral hearing loss, dizziness, and facial pain. During tumor resection, one part of SPV complex was injured, then cerebellar edema develops.

Conclusion:

This case provides an overview of surgical complication associated with venous sacrifice. This would support the agreement to preserve SPV regarding risks and improve the quality of surgical decision making.

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.

Preservation of Coexisting Normal Superior Petrosal Vein in the Microsurgical Treatment of Superior Petrosal Sinus Dural Arteriovenous Fistulas Assisted by Indocyanine Green Video Angiography

BACKGROUND

Superior petrosal sinus (SPS) dural arteriovenous fistulas (DAVFs) are a common subtype of tentorial DAVFs that often require microsurgical treatment. We have noted a rare condition involving the presence of a coexisting normal superior petrosal vein (SPV) during surgery for SPS DAVFs; this condition has not been reported in the literature. Identification and preservation of coexisting normal veins are crucial to prevent venous complications.

METHODS

We reviewed data of 12 patients with SPS DAVFs who underwent microsurgical treatment. Intraoperative indocyanine green video angiography was used to confirm the location of the fistula and identify the normal SPV. Postoperative radiologic examination was performed, and the clinical outcome was evaluated with the modified Rankin Scale.

RESULTS

A coexisting normal functional SPV was found in 6 cases. Analysis of the tributaries of the SPV showed the vein of the cerebellopontine fissure was the most frequent arterialized drainage vein (66.7%), while the pontotrigeminal vein was the most frequent normal drainage vein (45.5%). The DAVFs were easily identified and disrupted using intraoperative indocyanine green video angiography. The normal SPV was also successfully preserved. All 6 patients experienced good clinical and radiologic outcomes.

CONCLUSIONS

An SPS DAVF can coexist with a normal functional SPV, which should be preserved. Use of indocyanine green video angiography is an efficient way to identify the normal SPV.