Fusion for subaxial bow hunter's syndrome results in remote osseous remodeling of the hyperostotic growth responsible for vertebral artery compression

Background:

The authors present a previously unreported case of a patient with diffuse idiopathic skeletal hyperostosis (DISH) who developed bow hunter’s syndrome (BHS) or positional vertebrobasilar insufficiency. In addition, the authors demonstrate angiographic evidence of remote osseous remodeling after segmental fusion without direct decompression of the offending bony growth. BHS is a rare, yet well established, cause of posterior circulation ischemia and ischemic stroke. Several etiologies such as segmental instability and spondylosis have been described as causes, however, DISH has not been associated with BHS before this publication.

Case Description:

A 77-year-old man who presented with BHS was found to have cervical spine changes consistent with DISH, and angiography confirmed right vertebral artery (VA) stenosis at C4–5 from a large pathological elongation of the right C5 lateral mass. Head rotation resulted in occlusion of the VA. The patient underwent an anterior cervical discectomy and fusion and reported complete resolution of his symptoms. A delayed angiogram and CT of the cervical spine demonstrated complete resolution of the baseline stenosis, no dynamic compression, and remote osseous remodeling of the growth, respectively.

Conclusion:

This case represents the first publication in the literature of DISH as a causative etiology of BHS and of angiographic data demonstrating resolution of a compressive osseous pathology without direct decompression in BHS.

Bow Hunter's Syndrome: A rare cause of vertebrobasilar insufficiency

Bow Hunter's syndrome, also referred to as rotational occlusion of the vertebral artery, is caused by dynamic compression of a patient's dominant vertebral artery. We reported a case of successful clinical and imaging work up of Bow Hunter's Syndrome that occurred in a 79-year-old female patient. We discussed the clinical presentation, imaging findings, and subsequent management options of this rare syndrome. The gold standard for diagnosis is dynamic cerebral angiography, which allows the reproduction of symptoms with head turn greater than 30-45 degrees. Subsequent management is based on the underlying etiology causing rotational compression.