Rotational Vertebral Artery Compression : Bow Hunter's Syndrome

Anatomical and surgical considerations for Bow Hunter's syndrome in an elderly patient

Bow Hunter's syndrome (BHS) is an uncommon condition characterized by impingement of one of the two vertebral arteries induced by cervical rotation, causing symptomatic vertebrobasilar insufficiency of the posterior cerebral circulation. We report a case of BHS in an 84-year-old male. Two months following a motor vehicle accident, the patient presented to an urgent care facility with subsequent transfer to the emergency department with complaints of lightheadedness upon right-lateral head movement. A cerebral angiogram demonstrated mild focal stenosis in the dominant left vertebral artery at the C2 level when in neutral position with significant worsening of the stenosis in the right-lateral head position with absent anterograde flow, consistent with BHS. Resultantly, the patient was referred for neurosurgery and successfully underwent placement of right-sided C2-C4 postero-lateral instrumentation and left-sided C2-C3 laminar screws projected towards the right side. This case highlights the importance of imaging in BHS diagnosis and guidance for treatment, as well as the need for a surgical standard of care for BHS patients.

Double Transverse Foramina-An Anatomical Basis for Possible Vertebrobasilar Insufficiency Risk and Vertebral Artery Injury

Cervical vertebrae may exhibit the anomalous presence of a double transverse foramen (DTF) that may impact the anatomy of related structures that traverse the cervical region, such as the vertebral artery (VA). This retrospective anatomical study utilized CT angiography cervical scans to examine the prevalence of DTF, VA, and TF areas. The subjects were separated into two groups: normal TF (NTF group; 26 males and 21 females) and double TF (DTF group; 21 males and 24 females). The males presented significantly higher TF area values (30.31 ± 4.52 mm2) than the females (27.48 ± 1.69 mm2) in the NTF group (p = 0.006). The sex differences disappeared when a DTF was present (p = 0.662). There were no differences in the VA area values between the sexes in both the NTF and DTF groups (p = 0.184). No significant differences in the VA area values between males of the NTF and DTF groups (p = 0.485) were noted. The DTF subjects presented an increased VA/TF area ratio than the NTF subjects (p < 0.001). This study showed that DTF presence reduced the TF area. In contrast, the VA area did not change despite the decreasing TF area. This might be an anatomical risk for transient vertebrobasilar insufficiency in subjects with DTF, especially in females, because VA space in the TF is less in DTF subjects than in NTF subjects. This may lead to easy VA compression in DTF subjects following neck trauma.

Cerebellar Ischemic Stroke Secondary to Rotational Non-Dominant Vertebral Artery Occlusion (RVAO): A Rare Complication Following Supratentorial Surgery

Non-traumatic vertebrobasilar stroke syndrome is rare. Many etiological mechanisms have been described over the years, with the dynamic occlusion of one vertebral artery following head rotation (RVAO) being one of them. We report the case of a patient undergoing surgery for supratentorial metastasis, who postoperatively developed a cerebellar ischemic stroke secondary to RVAO. Postoperative imaging showed a right hypoplastic VA; so, a transient occlusive mechanism was thought to be responsible for the postoperative cerebellar stroke. Although rare, RVAO can occur following head rotation during patient positioning for neurosurgical procedures.

Ultrasound during neck rotation to reveal a case of positional occlusion of the internal carotid artery

Positional occlusion of the internal carotid artery is an unusual phenomenon. Reports are scarce in the literature and generally related to compression by external agents when the head is rotated. Cases with no extrinsic etiology are even more uncommon and require high suspicion to avoid misdiagnosis. We present a case of a patient with intermittent internal carotid occlusion depending on the position of the head with no external agent identified. Due to the dynamic characteristics of this presentation, diagnostic tests yielded contradictory results. Carotid ultrasound during neck rotation revealed the positional occlusion. Ultrasound is a versatile technique to explore the carotid arteries in different angles of the neck, useful if positional pathology is suspected.

Ischemic Stroke Secondary to Dynamic Vertebral Artery Stenosis: Case Report and Review of the Literature

Ischemic stroke secondary to dynamic vertebral artery stenosis or occlusion, also known as “bow hunter's syndrome,” is a rare stroke mechanism. We report a case of a 24-year-old man with multiple hereditary exostosis (MHE) diagnosed at childhood. His first presentation to a neurologist was due to neck pain and clinical syndrome suggestive of ischemia in the vertebrobasilar territory. A therapeutic occlusion was done successfully without complication. The patient was discharged two days later on aspirin alone. In follow up one year later he continued to be symptom free. Moreover, this stroke mechanism has been reported extensively in the literature in isolation or secondary to many underlying diseases. In total, there are 168 cases reported in the published English literature, in either case reports or small series. In this review, we found that by far, vertebral artery occlusion at the atlanto-axial (C1-2) level dominated most reported cases. The most frequent presentation that led to further investigation was syncope or pre-syncope provoked by head rotation to one side. To our knowledge, there is no previous report of any stroke syndrome related to MHE before our case. In this paper, we report the first case secondary to MHE and review the literature up to date since the first reported case in 1952.

The Enduring Controversy of Cervicogenic Vertigo, and Its Place among Positional Vertigo Syndromes

The idea of cervicogenic vertigo (CV) was proposed nearly a century ago, yet despite considerable scrutiny and research, little progress has been made in clarifying the underlying mechanism of the disease, developing a confirmatory diagnostic test, or devising an appropriately targeted treatment. Given the history of this idea, we offer a review geared towards understanding why so many attempts at clarifying it have failed, with specific comments regarding how CV fits into the broader landscape of positional vertigo syndromes, what a successful diagnostic test might require, and some practical advice on how to approach this in the absence of a diagnostic test.

Atypical presentation of rotational vertebral artery insufficiency: illustrative case

BACKGROUND

Rotational vertebral artery insufficiency (RVAI), also known as bow hunter’s syndrome, is an uncommon cause of vertebrobasilar insufficiency that leads to signs of posterior circulation ischemia during head rotation. RVAI can be subdivided on the basis of the anatomical location of vertebral artery compression into atlantoaxial RVAI (pathology at C1-C2) or subaxial RVAI (pathology below C2). Typically, RVAI is only seen with contralateral vertebral artery pathologies, such as atherosclerosis, hypoplasia, or morphological atypia.

OBSERVATIONS

The authors present a unique case of atlantoaxial RVAI due to rotational instability, causing marked subluxation of the C1-C2 facet joints. This case is unique in both the mechanism of compression and the lack of contralateral vertebral artery pathology. The patient was successfully treated with posterior C1-C2 instrumentation and fusion.

LESSONS

When evaluating patients for RVAI, neurosurgeons should be aware of the variety of pathological causes, including rotational instability from facet joint subluxation. Due to the heterogeneous nature of the pathologies causing RVAI, care must be taken to decide if conservative management or surgical correction is the right course of action. Because of this heterogeneous nature, there is no set guideline for the treatment or management of RVAI.

Can the transverse foramen/vertebral artery ratio of double transverse foramen subjects be a risk for vertebrobasilar transient ischemic attacks?

The C6 is the cervical vertebra into which the vertebral artery enters the passage of the transverse foramen and it is the vertebra most affected by double transverse foramina. There is currently little information about the relation between the vertebral artery and the double transverse foramen in C6. We aimed to test whether subjects with a double transverse foramen in C6 have a reduced transverse foramen/vertebral artery ratio when compared with normal anatomy subjects who possess a single transverse foramen which may be a risk for transient vertebral artery stenosis. We measured the area of the transverse foramen and the vertebral artery in 27 double transverse and 56 normal anatomy subjects using computed tomography angiography. We found significant differences in the area of the transverse foramen between double transverse and normal subjects (P < 0.001) but not between the vertebral artery area of double transverse and normal subjects (P = 0.829). The subjects with double transverse foramina have a reduced transverse foramen/vertebral artery ratio, which may be a possible risk for transient vertebral artery stenosis.

Occipital Bony Abnormality and Multiple Strokes in a Pediatric Patient: Case Report and Review of the Current Literature

This study presents a case of a 15-year-old boy who had a right vertebral artery dissection with distal embolization from repeated trauma from an occipital bony spicule. The authors hypothesize that this bony spicule was contacting the left vertebral artery during head rotation, resulting in trauma to the vessel and formation of emboli which then showered distally, causing strokes in the posterior circulation of the brain. This specific phenomenon has previously been reported three times, only one of which was in pediatric literature. It is important for individuals to be aware of this rare anatomic cause of vertebral artery dissection in patients presenting with an odd constellation of symptoms related to strokes from vertebro-basilar system. Treatment options including early intervention with intravascular coil embolization are also discussed.

Bow Hunter's Syndrome: Surgical Management (Video) and Review of the Literature

BACKGROUND

Bow Hunter's syndrome (BHS) is a rare condition characterized by vertebrobasilar insufficiency associated with rotational vertebral artery occlusion during head movement. Many existing reports describe surgical management, although no single technique has proven superior.

OBJECTIVE

To review all reported cases of BHS with focus on outcomes of individual techniques as well as to present a video report of a posterior decompression without fusion performed at the authors' institution.

METHODS

We searched PubMed for all relevant articles of BHS available in the English language. Pertinent studies were further characterized into surgical technique performed and associated outcomes.

RESULTS

We included 27 studies in our review, excluding the case presented, for a total of 65 cases of BHS. These cases discuss anterior versus posterior decompressions, the need for fusion, coil embolization techniques, the efficacy of intraoperative dynamic angiography, and success rate with symptom resolution being the primary endpoint. A total of 53 cases underwent decompression without fusion, with an overall success rate of 90.6% (n = 48/53). Similarly, eleven cases underwent decompression with fusion, with a success rate of 91% (n = 10/11). Two additional cases opted for coil embolization, one of which reported resolution of symptoms. Furthermore, we present a video case of a posterior decompression without fusion with resolution of symptoms.

CONCLUSIONS

BHS remains a rare clinical condition with no clear superior method of treatment. Rates of symptom resolution are similar among cases undergoing decompression with or without fusion. Coil embolization has been reported with limited success in 2 cases.

Advances in the Pathogenesis, Diagnosis and Treatment of Bow Hunter's Syndrome: A Comprehensive Review of the Literature

Bow hunter's syndrome (BHS), also known as rotational vertebral artery (VA) occlusion syndrome, is a rare yet treatable type of symptomatic vertebrobasilar insufficiency resulting from mechanical occlusion or stenosis of the VA during head and neck rotation or extension. The symptoms of BHS range from transient vertigo to posterior circulation stroke. The underlying pathology is dynamic stenosis or compression of the VA by abnormal bony structures with neck rotation or extension in many cases, such as osteophyte, disc herniation, cervical spondylosis, tendinous bands or tumors. Imaging approaches, such as Doppler sonography, computed tomography and angiography, as well as magnetic resonance imaging and angiography, are widely used in the diagnosis and evaluation of this syndrome. Digital subtraction angiography with head rotation remains the gold standard diagnostic method. Conservative management, surgery and endovascular procedures are the three major treatment methods for BHS, whereas some symptomatic patients may need operative treatment including surgery and endovascular procedures when conservative management is not adequate.

Rare Etiology of Bow Hunter's Syndrome and Systematic Review of Literature

BACKGROUND

Bow Hunter's Syndrome is a mechanical occlusion of the vertebral artery which leads to a reduction in blood flow in posterior cerebral circulation resulting in transient reversible symptomatic vertebrobasilar insufficiency.

CASE DESCRIPTION

We present a case of Bow Hunter's syndrome in a 53-year-old male that occurred after the patient underwent surgical correction of a proximal left subclavian artery aneurysm. Shortly after the surgery, the patient began to complain of transient visual changes, presyncopal spells, and dizziness upon turning his head to the left. A transcranial doppler ultrasound confirmed the diagnosis of Bow Hunter's syndrome.

SYSTEMIC REVIEW

We analyzed the data on 153 patients with Bow Hunter's syndrome from the literature. An osteophyte was the most common cause of vertebral artery occlusion, and left vertebral artery was more commonly involved in patients with Bow Hunter's syndrome. Dynamic angiography was the definitive imaging modality to confirm the diagnosis, and surgery was most successful in alleviating symptoms.

CONCLUSION

We believe that this is the first case of iatrogenic Bow Hunter's syndrome after surgical intervention for an aneurysm repair, and the largest review of literature of Bow Hunter's syndrome. Dynamic angiography is the gold standard for the diagnosis of Bow Hunter's syndrome. Surgery should be considered as the primary treatment approach in these patients, especially those who have bony compression as the etiology.

Chronic neck pain: making the connection between capsular ligament laxity and cervical instability

The use of conventional modalities for chronic neck pain remains debatable, primarily because most treatments have had limited success. We conducted a review of the literature published up to December 2013 on the diagnostic and treatment modalities of disorders related to chronic neck pain and concluded that, despite providing temporary relief of symptoms, these treatments do not address the specific problems of healing and are not likely to offer long-term cures. The objectives of this narrative review are to provide an overview of chronic neck pain as it relates to cervical instability, to describe the anatomical features of the cervical spine and the impact of capsular ligament laxity, to discuss the disorders causing chronic neck pain and their current treatments, and lastly, to present prolotherapy as a viable treatment option that heals injured ligaments, restores stability to the spine, and resolves chronic neck pain. The capsular ligaments are the main stabilizing structures of the facet joints in the cervical spine and have been implicated as a major source of chronic neck pain. Chronic neck pain often reflects a state of instability in the cervical spine and is a symptom common to a number of conditions described herein, including disc herniation, cervical spondylosis, whiplash injury and whiplash associated disorder, postconcussion syndrome, vertebrobasilar insufficiency, and Barré-Liéou syndrome. When the capsular ligaments are injured, they become elongated and exhibit laxity, which causes excessive movement of the cervical vertebrae. In the upper cervical spine (C0-C2), this can cause a number of other symptoms including, but not limited to, nerve irritation and vertebrobasilar insufficiency with associated vertigo, tinnitus, dizziness, facial pain, arm pain, and migraine headaches. In the lower cervical spine (C3-C7), this can cause muscle spasms, crepitation, and/or paresthesia in addition to chronic neck pain. In either case, the presence of excessive motion between two adjacent cervical vertebrae and these associated symptoms is described as cervical instability. Therefore, we propose that in many cases of chronic neck pain, the cause may be underlying joint instability due to capsular ligament laxity. Currently, curative treatment options for this type of cervical instability are inconclusive and inadequate. Based on clinical studies and experience with patients who have visited our chronic pain clinic with complaints of chronic neck pain, we contend that prolotherapy offers a potentially curative treatment option for chronic neck pain related to capsular ligament laxity and underlying cervical instability.