Intracranial meningioma at foramen magnum presenting as bow hunter's syndrome via V4 segment compression:...

Bow hunter's syndrome (BHS) occurs when physiological head rotation or extension leads to dynamic vertebral artery (VA) occlusion and transient vertebrobasilar insufficiency. Most cases are due to degenerative compression at the V2-V3 segments. Tumor-related BHS is exceedingly rare, and to date, compression of the intradural V4 segment by a neoplasm has not been reported.

A 77-year-old male developed episodic right-sided weakness, hemisensory loss, and dizziness that recurred reliably with leftward head rotation and resolved immediately on returning to a neutral position. MRI demonstrated a homogeneously enhancing intradural extramedullary mass at the left foramen magnum displacing the VA and compressing the cervicomedullary junction. The patient underwent midline suboccipital craniotomy, C1 laminectomy, and partial occipital condylectomy for microsurgical resection. Gross-total removal was achieved, decompressing the V4 segment and restoring normal vascular caliber. Pathology confirmed a grade I meningioma. All positional symptoms resolved postoperatively, and postoperative MRI showed no residual tumor.

This case represents the first documented instance of BHS caused by tumor-related V4 compression. It underscores the importance of considering intracranial lesions in patients with reproducible, position-dependent vertebrobasilar symptoms and highlights resection as curative therapy when vascular compromise arises from space-occupying pathology. https://thejns.org/doi/10.3171/CASE25833.