STUDY DESIGN: A case report.
OBJECTIVE: To illustrate a rare case of bow hunter's syndrome in a patient with 
significant contralateral vertebral artery (VA) occlusive disease.
SUMMARY OF BACKGROUND DATA: Bow hunter's syndrome is an uncommon condition in 
which the VA is symptomatically occluded during neck rotation. This case is 
interesting in that the patient had what appeared to be a normal right VA and 
occluded left VA when the head was in the neutral position. When the head was 
rotated 45 degrees to the left, the patient's right VA was occluded (bow 
hunter's finding), and it became apparent that the left VA was not completely 
occluded (as it appeared in the neutral position angiogram) but rather was 90% 
stenosed. The complete occlusion appearance in the neutral position was an 
angiographic phenomenon caused by competitive flow through the open right VA. 
When the patient rotated his head to the left, he occluded his right VA and had 
insufficient blood flow through the left VA, thus creating a symptomatic 
ischemic state.
METHODS: This case was studied using dynamic computed tomography imaging, 
single-photon emission computed tomography, transcranial Doppler ultrasound, 
brain stem auditory evoked potentials, and dynamic range-of-motion cerebral 
angiography.
RESULTS: The patient demonstrated bow hunter's syndrome as documented on 
clinical examination and history. Transcranial Doppler studies, dynamic computed 
tomography scanning, and cerebral/cervical angiography confirmed the diagnosis 
and revealed an interesting angiographic pattern, which explained the patient's 
symptoms and findings only when angiographic flow patterns were taken into 
consideration.
CONCLUSIONS: Bow hunter's syndrome should be suspected when a patient presents 
with reproducible vertebrobasilar symptoms on rotating the neck. Quantitative 
documentation using imaging and electroneurophysiologic tests is important when 
assessing this subjective process. Careful evaluation of the angiographic 
imagescan often help explain an odd flow pattern and provide the physician with 
a range of treatment options.