What is the management and treatment for Bow hunter syndrome?

Bow Hunter Syndrome: Management and Treatment

Diagnosis and Initial Evaluation

Bow hunter syndrome requires dynamic angiography with head rotation as the gold standard diagnostic method to confirm mechanical vertebral artery occlusion during neck rotation. 1, 2

Key Diagnostic Steps

• Obtain dynamic vascular imaging with the patient's head in neutral and rotated positions, as static imaging (standard MRA/CTA) will miss the diagnosis since compression only occurs with head movement 3, 4

• Perform dynamic ultrasonography and transcranial Doppler in different head positions to identify vertebral artery flow changes, which can provide clear diagnostic clues noninvasively 5, 3

• Use digital subtraction angiography with head rotation to definitively confirm the diagnosis and identify the exact level and side of compression 1, 2

• Identify the compression site, which is typically at C1-2 (50% of cases) or C5-7 (50% of cases), with the left vertebral artery most commonly affected (72.7%) 4

Treatment Algorithm

Conservative Management (First-Line)

Initial conservative management should be attempted first, consisting of cervical collar use to limit excessive neck rotation and patient education to avoid large-angle neck deflection. 5, 2

• Prescribe a cervical collar to restrict head rotation and prevent symptomatic vertebral artery compression 5

• Instruct patients to avoid provocative head positions, particularly rotation to the side that triggers symptoms 5, 4

• Reserve conservative management for patients with mild, infrequent symptoms who can reliably avoid triggering positions 1, 2

Surgical Management (Definitive Treatment)

Surgical decompression without fusion is the definitive treatment for symptomatic patients who fail conservative management or present with posterior circulation stroke. 2, 4

Surgical Approach Selection

• Use posterior decompression for atlantoaxial (C1-2) compression, which accounts for 50% of cases and provides excellent results with low morbidity 3, 2, 4

• Use anterior decompression for subaxial (C5-7) compression, which also accounts for 50% of cases 4

• Perform decompression alone without fusion initially, as fusion is typically not required and adds unnecessary morbidity 2, 4

Surgical Outcomes

• Expect excellent clinical and radiological results with tailored vertebral artery decompression, with complete resolution of paroxysmal symptoms in most patients 3, 2, 4

• Treatment-related morbidity is low when appropriate surgical technique is used 2, 4

• Monitor for late cervical instability, which may develop years after decompression (reported in one patient at 5 years) and require subsequent fusion 4

Endovascular Procedures (Alternative)

Endovascular procedures represent an alternative treatment option, though surgical decompression remains the primary definitive treatment with better long-term outcomes. 1

Clinical Pitfalls and Caveats

• Do not rely on static vascular imaging alone, as standard MRA, CTA, or MRI will appear normal since compression is dynamic and position-dependent 3, 4

• Consider bow hunter syndrome in young patients with poor neck posture and symptoms of dizziness, nausea, vomiting, and neck rotation-related symptoms, as loss of cervical physiological curvature may contribute to the syndrome 5

• Recognize that symptoms range from transient vertigo to posterior circulation stroke, including medullary and cerebellar infarctions, making early diagnosis critical to prevent irreversible neurological deficits 3, 2

• Identify the contralateral rotation pattern, where in 54.5% of cases, rotation to the side opposite the compressed artery produces symptoms 4

• Perform dynamic angiography even when clinical suspicion is high, as this remains the only definitive diagnostic test and guides surgical planning 1, 2, 4

Treatment Decision Framework

For patients with recurrent transient ischemic attacks or any posterior circulation stroke: Proceed directly to surgical decompression after confirming diagnosis with dynamic angiography 3, 2

For patients with mild, infrequent symptoms: Trial conservative management with cervical collar and activity modification for 3 months, then reassess 5

For patients who fail conservative management or have progressive symptoms: Proceed to surgical decompression via the appropriate approach based on compression level 2, 4