Location of the abducens nerve stretched by a tortuous vertebrobasilar artery in trigeminal neuralgia

Analyzing the risk factors of unilateral trigeminal neuralgia under neurovascular compression

Background

This study aimed to explore the risk factors and potential causes of unilateral classical or idiopathic trigeminal neuralgia (C-ITN) by comparing patients and healthy controls (HCs) with neurovascular compression (NVC) using machine learning (ML).

Methods

A total of 84 C-ITN patients and 78 age- and sex-matched HCs were enrolled. We assessed the trigeminal pons angle and identified the compressing vessels and their location and severity. Machine learning was employed to analyze the cisternal segment of the trigeminal nerve (CN V).

Results

Among the C-ITN patients, 53 had NVC on the unaffected side, while 25 HCs exhibited bilateral NVC, and 24 HCs showed unilateral NVC. By comparing the cisternal segment of CN V between C-ITN patients on the affected side and HCs with NVC, we identified the side of NVC, the compressing vessel, and certain texture features as risk factors for C-ITN. Additionally, four texture features differed in the structure of the cisternal segment of CN V between C-ITN patients on the unaffected side and HCs with NVC.

Conclusion

Our findings suggest that the side of NVC, the compressing vessel, and the microstructure of the cisternal segment of CN V are associated with the risk of C-ITN. Furthermore, microstructural changes observed in the cisternal segment of CN V on the unaffected side of C-ITN patients with NVC indicate possible indirect effects on the CN V to some extent.

Abducens Nerve Palsy Due to Neurovascular Compression

BACKGROUND

Neurovascular compression (NVC) as the cause of abducens nerve palsy is an infrequent event. Only a small number of cases have been reported in the literature, and the efficacy of microvascular decompression (MVD) for abducens nerve palsy remains unclear.

METHODS

We reviewed previously reported cases of abducens nerve palsy caused by NVC and added our own cases. We analyzed the clinical characteristics of vascular compression abducens nerve palsy and assessed the indication for MVD.

RESULTS

Twenty-two patients with isolated abducens nerve palsy due to vascular compression were confirmed in total, consisting of 20 patients (19 publications) from the literature search and 2 cases from our experienced cases. All patients had no possible causes for isolated abducens nerve palsy except the NVC on the nerve root. Unlike the sudden onset in the typical abducens nerve palsy, all patients demonstrated gradual development of the symptom in NVC-related abducens palsy. Careful observation was the most common strategy in most patients; however, no noticeable improvement was reported in the conservative treatment. Surgical intervention was performed in 6 patients after observation for several months and showed favorable outcomes in all cases.

CONCLUSIONS

Vascular compression could be a potential cause of abducens nerve palsy. Gradual onset or episodic symptom of abducens palsy with a definitive radiological finding of vascular compression deserves considering MVD for abducens nerve palsy.

Macrovascular Decompression with the Transposition Method Using Teflon Sling for Trigeminal Neuralgia Caused by the Vertebrobasilar Artery

OBJECTIVE

Complete separation of the vertebrobasilar artery (VBA) from the trigeminal nerve by microvascular decompression is technically challenging. This paper evaluates the transposition method using Teflon sling for trigeminal neuralgia (TN) caused by the VBA.

METHODS

Retrospective review of 32 patients including 2 patients with tic convulsif. Mobilization of the VBA in the anteromedial-caudal direction and repositioning of the VBA using Teflon sling and fibrin glue were performed. Pre- and postoperative pain were evaluated with the Barrow Neurological Institute (BNI) pain intensity score. Duration of surgery and postoperative neurologic complications were reviewed.

RESULTS

Preoperative BNI score ranged from III to V. Postoperative BNI score I was observed in 30 patients, II in 1 patient, and V in 1 patient as recurrence. Abducens nerve palsy was observed in 9 patients but was transient in 8. Permanent hearing loss was observed in 6 patients. Transient mild lower cranial nerve palsy was recorded in 2 patients with tic convulsif. Average surgical time was 290 minutes.

CONCLUSIONS

Our method for trigeminal neuralgia caused by VBA was very effective, but the complication rate of cranial nerve disorders was also high. A high rate of complications implied the technical difficulty of extensive vascular mobilization requiring long duration of surgery. Macrovascular decompression surgery is more descriptive of this surgery instead of microvascular decompression surgery.