Understanding Hemifacial Spasm and Vascular Anomalies

Hemifacial spasm (HFS) is a distressing neurological condition usually caused by vascular contact with the facial nerve. However, identifying a rare vertebral artery fenestration as the underlying cause presents unique challenges for surgical intervention. A recent illustrative case highlights the clinical importance of recognizing these complex vascular architectures during preoperative planning.

A man in his 30s sought treatment after a seven-year history of right-sided facial spasms. Magnetic resonance imaging (MRI) initially confirmed neurovascular compression at the root exit zone of the facial nerve. Specifically, MR angiography revealed an unusual artery running parallel to the right vertebral artery, creating a large fenestrated segment. Furthermore, three-dimensional CT angiography demonstrated that this anomalous structure formed a common trunk for both the anterior inferior cerebellar artery (AICA) and the posterior inferior cerebellar artery (PICA).

Surgical Nuances in Vertebral Artery Fenestration Cases

The surgical team performed a microvascular decompression (MVD) to address the compression. Notably, they utilized real-time abnormal muscle response (AMR) monitoring to ensure the efficacy of the decompression during the procedure. This technology allowed the surgeons to confirm sufficient arterial transposition while carefully protecting sensitive brainstem perforators. Consequently, the patient achieved complete resolution of his spasms immediately following the surgery without experiencing any postoperative complications.

Moreover, the authors suggest that a large vertebral artery fenestration likely represents a persistent primitive lateral basilovertebral anastomosis from embryonic development. These variants often impose significant limitations on how much an artery can be moved. Therefore, surgeons must possess a precise understanding of the vascular anatomy to avoid injuring perforating branches during transposition. Ultimately, this case proves that even rare anomalies can be managed safely with advanced imaging and intraoperative monitoring.

Key Takeaways for Clinical Practice

Clinicians should consider detailed vascular imaging when standard HFS cases show unusual features on initial scans. Specifically, the presence of a vertebral artery fenestration requires a tailored surgical strategy. Successful outcomes depend on balancing the need for nerve decompression with the preservation of critical blood supply to the brainstem.

Frequently Asked Questions

What is a vertebral artery fenestration?

This is a rare congenital anomaly where the lumen of the vertebral artery is divided into two separate channels that eventually rejoin. It occurs due to incomplete fusion or regression of vessels during embryonic development.

How does this anomaly impact hemifacial spasm surgery?

The presence of a fenestration or a common arterial trunk often limits the mobility of the offending vessel. Surgeons must use extra caution and intraoperative monitoring to ensure the nerve is decompressed without stretching or damaging small perforating arteries.

Is microvascular decompression effective for these rare cases?

Yes, microvascular decompression remains the gold standard. As demonstrated in this case, using real-time monitoring and careful microsurgical techniques can lead to a complete cure even when complex vascular variants are present.

Disclaimer: This content is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Refer to the latest local and national guidelines for clinical practice.

References

Matsumiya K et al. Microvascular decompression for hemifacial spasm associated with large fenestration of the vertebral artery: illustrative case. J Neurosurg Case Lessons. 2026 Mar 09. doi: undefined. PMID: 41802292.

Nomura S, Kawamata T, Tominaga T, Okada Y. Hemifacial spasm associated with the vertebral artery fenestration. Neurol India. 2015;63(3):443-4.

Ozpinar A, et al. Vertebral Artery Fenestration. Cureus. 2015 Jan 30;7(1):e245.