Rotational vertebrobasilar ischemia: hemodynamic assessment and surgical treatment

Evaluation of Acute Dizziness and Vertigo

Dizziness and vertigo are common presenting symptoms in acute care settings. This article describes the most common causes of acute dizziness and vertigo with practical, evidence-based guidance on evaluation of these patients. A timing-and-triggers approach should be used to first characterize the patient's vestibular symptoms as continuous or episodic. If acute and continuous, determine whether symptoms are post-exposure or spontaneous. If episodic, determine whether symptoms are triggered or spontaneous. Classify the patient as having post-exposure acute vestibular syndrome (AVS), spontaneous AVS, triggered episodic vestibular syndrome (EVS), or spontaneous EVS.

Syncope Induced by Dynamic Head and Shoulder Motion in the Setting of Left Subclavian Stenosis

INTRODUCTION

Dynamic vertebral artery insufficiency is a rare vascular phenomenon characterized by insufficient flow of the posterior cerebral circulation induced by dynamic motion of the head. Prior case reports have been limited to vertebral artery occlusion by cervical osteophytes or other structural impingements.

CASE REPORT

In this case report, we discuss the unusual case of a 61-year-old female with a history of vertigo, diplopia, nystagmus, and left subclavian stenosis admitted to the hospital for syncope elicited by a left head turn and left shoulder raise. Transcranial Doppler (TCD) ultrasound and angiography showed evidence of dynamic vertebrobasilar insufficiency elicited by a left-head turn. Percutaneous stenting of the left subclavian artery led to the resumption of normal vessel flow as assessed by TCD and the resolution of the patient's symptoms.

CONCLUSIONS

This case highlights an unusual cause of dynamic vertebrobasilar insufficiency induced by head turn and/or left shoulder raise due to subclavian stenosis, diagnosed by TCD and angiography, and successfully treated with subclavian artery stenting.

Transcortical resection of a giant bilobed falcine meningioma

INTRODUCTION

Falcine meningiomas present significant surgical challenges because they often involve the falx bilaterally, are concealed by a significant amount of normal brain parenchyma and are frequently deep in location and in close proximity to the anterior cerebral arteries. Many prefer the interhemispheric approach for these lesions, but this operative corridor is not without risk as venous infarctions and cortical injury can occur.

CLINICAL PRESENTATION

We present an alternative technique utilizing a transcortical approach to resect a giant, bilobed falcine meningioma in a 68-year-old female who presented with progressive abulia, urinary incontinence, and bilateral lower extremity weakness over 2 years. A unilateral right frontal craniotomy and a corticectomy through the right superior frontal gyrus was used to safely resect the entire tumor. The patient tolerated the procedure well and was discharged home without issue. Pathology demonstrated that the lesion was an atypical meningioma and she subsequently received adjuvant fractionated radiotherapy. At 2-year follow-up, she has no neurologic deficits, never developed any postoperative seizures and has not had any evidence of tumor recurrence.

CONCLUSION

The transcortical approach can be used as a safe alternative for resecting falcine meningiomas without adding significant undue risk to the patient.

Bow Hunter's syndrome surgical approach and outcome: Two new cases and literature review

Background

Bow Hunter's syndrome (BHS) is a rare entity known as rotational vertebral artery occlusion syndrome. Classically, it presents with nausea, vertigo, and dizziness elicited by extension or rotation of the neck. There are several management approach modalities, including surgical and nonsurgical alternatives.

Methods

We conducted an electronic database search on PubMed and Scopus. The search was performed on February 18, 2024, using a combination of keywords related to Bow Hunter Syndrome regarding management. From the latter query, 97 results followed, from which we included 76 and excluded 21 due to the information being irrelevant to our study and non-retrievable publications.

Results

A total of 121 patients were retrieved. The mean age of presentation was 50 years, with a female-to-male ratio of 3:1. There were 108 adult cases, and only 13 were pediatric and adolescents. Symptoms were elicited by right rotation (46%). The most affected levels were C1-C2 (44%). The anterior approach was the most common (40%) and had a better outcome (84%), followed by the posterior (30%), which had more cases with partial recovery (19% vs. 16%).

Conclusion

BHS management is still challenging as there are many factors that we must consider when deciding on the approach. There is inconclusive evidence on the proper management of these patients. Although the suggestions found in our review and our experience are valuable, no definitive management ensures a good quality of life and outcome for these patients. Further research is needed on this topic.

Safety and efficacy of dynamic catheter-directed cerebral digital subtraction angiography for diagnosis of bowhunter syndrome spectrum disorders: A systematic review of the literature

INTRODUCTION

Dynamic catheter-directed cerebral digital subtraction angiography (dcDSA) is the gold standard for diagnosing dynamic vascular occlusion syndromes such as bowhunter syndrome (BHS). Nonetheless, concerns about its safety exist and no standardized protocols have been published to date.

METHODS

We describe our methodology and insights regarding the use of dcDSA in patients with BHS. We also perform a systematic literature review to identify cases of typical and atypical presentations of BHS wherein dcDSA was utilized and report on any procedural complications related to dcDSA.

RESULTS

Our study included 104 cases wherein dcDSA was used for the diagnosis of BHS. There were 0 reported complications of dcDSA. DcDSA successfully established diagnosis in 102 of these cases. Thirty-eight cases were deemed atypical presentations of BHS. Fourteen patients endorsed symptoms during neck flexion/extension. In eight cases, there was dynamic occlusion of bilateral vertebral arteries during a single maneuver. Three patients had multiple areas of occlusion along a single vertebral artery (VA). An anomalous entry of the VA above the C6 transverse foramen was observed in four patients. One patient had VA occlusion with neutral head position and recanalization upon contralateral lateral head tilt.

CONCLUSION

Our study highlights the safety and diagnostic benefits of dcDSA in characterizing the broad spectrum of BHS pathology encountered in clinical practice. This technique offers a powerful means to evaluate changes in cerebral blood flow and cervical arterial morphology in real time, overcoming the constraints of static imaging methods. Our findings pave the way for further studies on dcDSA to enhance cross-sectional imaging methods for the characterization of BHS and other dynamic vascular occlusion syndromes.

A rare case of positional vertebrobasilar ischemia with the retrograde flow of the vertebral artery

Positional vertebrobasilar ischemia, also known as Bow hunter stroke, is typically caused by mechanical compression of the vertebral artery (VA). On the other hand, subclavian steal syndrome is incidentally detected by vertigo, syncope or loss of consciousness due to the steal phenomenon. A 61-year-old man suffered from near syncope when he turned his head to the left side. Although asymmetric arm blood pressure of the right dominant was observed, arm claudication was not detected. Computed tomographic angiography and magnetic resonance imaging revealed total occlusion of the left subclavian artery, hypoplasia of the right VA and an incomplete circle of Willis. Furthermore, carotid Doppler ultrasonic echography revealed retrograde blood flow of the left VA. It means that head rotation might occur in the left VA ischemia. An axillary-axillary bypass surgery was performed and ultrasonic echography showed anterograde effective blood flow of the left VA after the procedure.

Clinical Reasoning: A 37-Year-Old Man Presenting With Intermittent Dizziness and Brief Choreiform Movements

In this report, we describe the case of a 37-year-old man presenting with intermittent episodes of dizziness and choreiform movements. MRI of the head showed an acute infarction in the left cerebellar hemisphere and multiple chronic infarctions in the cerebellum and pons. Vessel imaging also showed dynamic stenoses in the posterior circulation. This case provides a framework for evaluating young patients with intermittent dizziness and recurrent strokes and highlights the need to combine anatomical angiographies or hemodynamic studies with head rotational behavior.

Rotational Vertebral Artery Syndrome (Bow Hunter's Syndrome): A Rare Differential Diagnosis in Patients With Syncope

Syncope is a common symptom in clinical practice. Rotational vertebral artery occlusion syndrome, also referred to as Bow Hunter's syndrome (BHS), is a rare condition associated with syncope and is caused by mechanical occlusion or stenosis secondary to mechanical compression of the vertebral artery during head rotation. BHS is associated with a multifactorial etiology; however, in most cases, this condition is attributed to degenerative changes. A 53-year-old man visited our hospital for the evaluation of fainting and dizziness episodes that occurred when he turned his head. Evaluation as an outpatient in the Department of Neurology showed a positive result on the Frenzel goggle test. Transfemoral cerebral angiography performed at the Department of Neurosurgery revealed stenosis of the proximal right vertebral artery. Complete occlusion of the vertebral artery was observed, and the head was turned to the right. Decompression and fusion were performed, and the contributory lesion was completely removed. Postoperative imaging confirmed complete removal of the spur and sufficient vertebral artery decompression; the patient's symptoms resolved postoperatively.

Anterior decompression of persistent vertebral artery occlusion caused by the cervical facet joint originated osteophyte

BACKGROUND

Persistent vertebral artery occlusion caused by compression of cervical facet joint originated osteophyte is exceptional rare. The authors sought to achieve adequate decompression of the vertebral artery (VA) with less stability decrease and movement restriction via the anterior approach, and to the authors' knowledge, no case of anterior decompression of this condition has been reported, and combination of intraoperative indocyanine green (ICG) angiography in the setting of VA decompression is also rare.

CASE PRESENTATION

A 77-year-old man presented continuous vertigo, unsteady gait and dysphagia with no relationship to the head movement. Preoperative computed tomography angiography (CTA) and digital substraction angiography (DSA) examination revealed the left vertebral artery was severely compressed at C_4-5 level with approximately 95% occlusion due to a left C_4-5 facet joint originated large osteophyte. Successful anterior decompression was performed without fusion and intraoperative ICG fluorescence angiography proved excellent blood flow. After surgery, vertebrobasilar insufficiency symptoms remarkably improved with no neurological deficits and no recurrence at 12 months' follow-up.

CONCLUSIONS

The authors' therapeutic strategy of anterior decompression was successful in treating VA compression due to facet joint overgrowth with adequate exposure, no stability decrease and movement restriction, and lower rates of neck pain and blood loss.

Transcortical approaches to large intraventricular tumors: a prospective case series of 20 patients

Background

Large intraventricular tumors (IVTs) impose technical and surgical challenges, due to their enormous sizes, mass effect, vast extensions, and vascularity.

Objective

The authors aim at presenting their results, clinical outcomes, and the surgical strategies in the management of large IVTs through transcortical approaches.

Methods

A prospective trial was conducted at the Main Hospital of Alexandria University, Egypt, between August 2018 and October 2020 on 20 patients harboring IVTs larger than 5 cm or bilaterally represented. The variables evaluated included the extent of resection, postoperative neurological deficits, blood loss, surgical approaches, intraoperative challenges, complications, adjuvant therapies, Glasgow Outcome Scale, hydrocephalus, and cerebrospinal fluid (CSF) diversion.

Results

The study included 20 cases (9 males and 11 females). Mean age at diagnosis was 16.1 years (range 1–45). Mean follow-up was 12 months (range 9–26). Primary tumor locations were ventricular body, atrium, temporal horn, and frontal horn in 11, 5, 3, and 1 cases, respectively. Main pathologies were central neurocytomas (7 patients/35%), ependymomas (3 patients/15%), and subependymal giant cell astrocytoma (SEGA) (3 patients/15%). Excision was gross total (n = 19) and near-total (n = 1). Significant intraoperative bleeding (n = 6). Postoperative minor intraventricular hemorrhage (n = 6), subdural collections (n = 8), hydrocephalus (n = 9), memory affection (n = 4), and motor deficits (n = 4). Postoperative Glasgow Outcome Scale of 5/5 (n = 20), no mortalities were recorded. preoperative seizures (n = 7), new onset postoperative seizures (n = 2).

Conclusion

Surgical approaches to large tumors of the lateral ventricles should be tailored to the variability of tumor locations, dimensions, extensions, and the individual morbid anatomy, in addition to the surgeon’s experience and preferences. Trans-cortical approaches can provide safe surgical corridors to tackle these challenging subtypes of IVTs with good clinical outcomes, tumor resectability rates, and seizure control.

Dynamic compression in vertebral artery dissection in children: apropos of a new protocol

PURPOSE

Our goals are (1) to report a consecutive prospective series of children who had posterior circulation stroke caused by vertebral artery dissection at the V3 segment; (2) to describe a configuration of the vertebral artery that may predispose to rotational compression; and (3) to recommend a new protocol for evaluation and treatment of vertebral artery dissection at V3.

METHODS

All children diagnosed with vertebral artery dissection at the V3 segment from September 2014 to July 2020 at our institution were included in the study. Demographic, clinical, surgical, and radiological data were collected.

RESULTS

Sixteen children were found to have dissection at a specific segment of the vertebral artery. Fourteen patients were male. Eleven were found to have compression on rotation during a provocative angiogram. All eleven underwent C1C2 posterior fusion as part of their treatment. Their mean age was 6.44 years (range 18 months-15 years). Mean blood loss was 57.7 mL. One minor complication occurred: a superficial wound infection treated with oral antibiotics only. There were no vascular or neurologic injuries. There have been no recurrent ischemic events after diagnosis and/or treatment. Mean follow-up was 33.3 months (range 2-59 months). We designed a new protocol to manage V3 dissections in children.

CONCLUSION

Posterior C1C2 fusion is a safe and effective option for treatment of dynamic compression in vertebral artery dissection in children. Institution of and compliance with a strict diagnostic and treatment protocol for V3 segment dissections seem to prevent recurrent stroke.

Repeated cerebellar infarction in the affected nondominant vertebral artery distribution with reversible vertebral artery occlusion elicited by head tilt: illustrative case

BACKGROUND

Bow hunter’s syndrome or stroke (BHS) is characterized by rotational vertebrobasilar insufficiency elicited by rotation of the neck. It is caused by dynamic and reversible occlusion of the vertebral artery (VA). Reversible symptoms of rotational vertebrobasilar insufficiency are described as bow hunter’s syndrome, although brain infarction is rarely reported as bow hunter’s stroke.

OBSERVATIONS

A 70-year-old man experienced repeated cerebellar infarctions three times in the posterior inferior cerebellar artery (PICA) distribution of the nondominant right VA connecting the basilar artery. The onset of symptoms indicating cerebellar infarcts and the patient’s head position changes were unrelated. Dynamic digital angiography (DA) revealed that the nondominant right VA was occluded by an osteophyte from the C4 vertebral body, and the right PICA branches were shown to be passing through the distal right VA from the left VA. These findings were observed when the patient’s head was tilted to the right. An arterio-arterial embolic mechanism was suggested as the cause of repeated cerebellar infarctions.

LESSONS

Transient nondominant VA occlusion has been rarely reported as a cause of BHS when the head is tilted. To confirm the diagnosis of BHS, additional head tilt is recommended when performing dynamic DA in patients with a cervical osteophyte.

Anterolateral approach for subaxial vertebral artery decompression in the treatment of rotational occlusion syndrome: results of a personal series and technical note

OBJECTIVES

To report the results of a retrospective series and a technical note about the anterolateral approach for the treatment of the rotational occlusion syndrome (ROS) involving the subaxial V2 segment of the vertebral artery (VA).

METHODS

We retrospectively reviewed the data of a cohort of patients that underwent an anterolateral approach to decompress the VA as they suffered from ROS secondary to a subaxial compression. A dynamic study with ultrasonography, CT, MRI, and catheter-based angiography were obtained in all cases. Severe symptomatology and cerebellar-brainstem strokes were indications for surgery. The anterolateral approach involved a pre-sternocleidomastoid precarotid exposure. The retro-longus colli and pre-scalenic corridors were used to access the C5-C6 and C3-C4 segment, respectively, and to perform the decompression.

RESULTS

Twelve patients were treated. Recurrent drop attacks were present in all cases. Osteophytes at C5 and C6 were the most common causes of subaxial VA compression. Anterior decompression stand-alone was performed in all but 1 patient. A recurrent laryngeal nerve palsy and a numbness of the C5 nerve root were the only complications observed, both transient. A satisfactory untethering of the VA with a complete recovery was achieved in all patients, apart from those with severe infratentorial strokes.

DISCUSSION READ

Anterolateral approach allows for an effective and safe treatment of the ROS involving the subaxial portion of the VA. Retro-longus colli and pre-scalenic corridors, developed through a precarotid exposure, have an anatomical rationale in decreasing the risks of complications. Decompression stand-alone is adequate in almost the totality of cases.

Subaxial Vertebral Artery Rotational Occlusion Syndrome: An Overview of Clinical Aspects, Diagnostic Work-Up, and Surgical Management

Extrinsic compression of the subaxial vertebral artery (VA) may cause rotational occlusion syndrome (ROS) and contribute to vertebrobasilar insufficiency potentially leading to symptoms and in severe cases, to posterior circulation strokes. The present literature review aimed to report the main clinical findings, diagnostic work-up, and surgical management of the subaxial VA-ROS, the diagnosis of which can be difficult and is often underestimated. An illustrative case is also presented. A thorough literature search was conducted to retrieve manuscripts that have discussed the etiology, diagnosis, and treatment of ROS. Total 41 articles were selected based on the best match and relevance and mainly involved case reports and small cases series. The male/female ratio and average age were 2.6 and 55.6±11 years, respectively. Dizziness, visual disturbances, and syncope were the most frequent symptoms in order of frequency, while C5 and C6 were the most affected levels. Osteophytes were the cause in >46.2% of cases. Dynamic VA catheter-based angiography was the gold standard for diagnosis along with computed tomography angiography. Except in older patients and those with prohibitive comorbidities, anterior decompressive surgery was always performed, mostly with complete recovery, and zero morbidity and mortality. A careful neurological evaluation and dynamic angiographic studies are crucial for the diagnosis of subaxial VA-ROS. Anterior decompression of the VA is the cure of this syndrome in almost all cases.

Should we abandon positional testing for vertebrobasilar insufficiency?

Positional testing for vertebrobasilar insufficiency (VBI) is used by physiotherapists as part of pre-manipulative screening protocols. Recently, the validity of the tests have been questioned because a negative test does not infer safety with cervical manipulative therapy but the reasoning surrounding this opinion may be questioned. While the positional tests were developed to test vertebral artery flow contralateral to the direction of head movement and the subsequent effect on cerebral blood supply, as inferred by symptom reproduction, ultrasound studies have shown that vertebral artery flow is inherently variable. Rather, the tests should be considered as testing for adequacy of collateral flow in particular head positions rather than decreased blood flow in a particular artery, with more attention to characteristics of symptom reproduction. We contend that positional testing for VBI remains valuable for testing adequacy of collateral flow, and also has an important place as part of the differential diagnosis of individuals with dizziness or imbalance. The physiotherapist's ability to differentially diagnose dizziness and recognise the presence or not of VBI is not only critical for prompt medical investigation and management because it is a risk factor for transient ischaemic events and stroke, but has important influences over management decisions regarding cervical musculoskeletal treatment including exercise interventions. Importantly, the positional tests should not be considered as tests of arterial integrity and used to assess the risk of damage to the vertebral or internal carotid artery or presence of cervical arterial dissection. Urgent research is needed before we abandon positional testing prematurely.

The ipsilateral interhemispheric transprecuneal approach: microsurgical anatomy, indications, and neurosurgical applications

Surgical treatment of intraventricular lesions is challenging because of their deep location, vascularization, and their complex relationships with white matter fibers. The authors undertook this study to describe the microsurgical anatomy of the white matter fibers covering the lateral wall of the atrium and temporal horn and to demonstrate how the ipsilateral interhemispheric transprecuneal approach can be safely used to remove lesions of this region sparing the anatomo-functional integrity of the fibers themselves. A detailed description of the approach including operative measurements is also given. The Klingler' technique with progressive identification of white matter fibers covering the lateral wall of the atrium and temporal horn was performed on ten formalin-fixed human hemispheres. Then, ten fresh, non-formalin-fixed non-silicon-injected adult cadaveric heads were analyzed for the simulation of the ipsilateral interhemispheric transprecuneal approach. Three illustrative cases are presented. The simulation of the interhemispheric transprecuneal approach on ten fresh non-formalin-fixed specimens showed that a 10 to 20 mm corticotomy perpendicular to the parieto-occipital sulcus at the junction with the cingulum allows a wide corridor for the exposure of the entire atrial cavity and the posterior third of the temporal horn. The ipsilateral interhemispheric transprecuneus approach represents a safe and effective option for tumors involving the atrium and the posterior third of the temporal horn.

The transcallosal transchoroidal approach to the diencephalic-mesencephalic junction: how I do it

BACKGROUND

Different approaches have to be considered for lesions of the diencephalic-mesencephalic junction based on the localization, extension of the lesion, and relationship to the ventricular system.

METHOD

We present the case of a young lady who presented with a cavernoma of the junction of midbrain and diencephalon after an episode of hemorrhage. The microsurgical anatomy of the trans-callosal trans-choroidal approach for this lesion is described along with its advantages and limitations.

CONCLUSION

The trans-choroidal approach allows adequate access to lesions of the diencephalic-mesencephalic junction that project into the third ventricle.

Compression Syndromes of the Vertebral Artery at the Craniocervical Junction

Compression syndromes of the vertebral artery that occur at the craniocervical junction are extremely rare causes of haemodynamic insufficiency of the posterior cerebral circulation. The aetiology of the compression syndrome may be a malformation, trauma, tumour, infection or degenerative pathology. This may lead to dynamic vertebral artery occlusion where the vessel courses around the atlas and the axis-the so-called V3 segment. This in turn may result in insufficient collateral flow to the posterior fossa. The clinical picture is a vertebrobasilar insufficiency syndrome of variable expression ranging from vertigo to posterior fossa stroke. The typical clinical presentation is syncope occurring during rotation of the head, also known as 'bow hunter's syndrome'. The workup is based on dynamic angiography and computed tomography angiography. The treatment of choice is surgical vascular decompression, resulting in a good clinical outcome. However, in some instances, atlantoaxial fusion may be indicated. Alternatively, conservative and endovascular options have to be considered in inoperable patients.

Approach to cervicogenic dizziness: a comprehensive review of its aetiopathology and management

PURPOSE

Though there is abundant literature on cervicogenic dizziness with at least half a dozen of review articles, the condition remains to be enigmatic for clinicians dealing with the dizzy patients. However, most of these studies have studied the cervicogenic dizziness in general without separating the constitute conditions. Since the aetiopathological mechanism of dizziness varies between these cervicogenic causes, one cannot rely on the universal conclusions of these studies unless the constitute conditions of cervicogenic dizziness are separated and contrasted against each other.

METHODS

This narrative review of recent literature revisits the pathophysiology and the management guidelines of various conditions causing the cervicogenic dizziness, with an objective to formulate a practical algorithm that could be of clinical utility. The structured discussion on each of the causes of the cervicogenic dizziness not only enhances the readers' understanding of the topic in depth but also enables further research by identifying the potential areas of interest and the missing links.

RESULTS

Certain peculiar features of each condition have been discussed with an emphasis on the recent experimental and clinical studies. A simple aetiopathological classification and a sensible management algorithm have been proposed by the author, to enable the identification of the most appropriate underlying cause for the cervicogenic dizziness in any given case. However, further clinical studies are required to validate this algorithm.

CONCLUSIONS

So far, no single clinical study, either epidemiological or interventional, has incorporated and isolated all the constitute conditions of cervicogenic dizziness. There is a need for such studies in the future to validate either the reliability of a clinical test or the efficacy of an intervention in cervicogenic dizziness.

Dynamic Arterial Compression in Pediatric Vertebral Arterial Dissection

Background and Purpose—

The pathogenesis of spontaneous pediatric vertebral artery dissections (VAD) is poorly understood but most often involves the V3 segment where C1 rotates on C2. We studied children with VAD with provocative digital catheter angiography and found an association between VAD and rotational compression.

Methods—

Seven boys (12 months to 9 years; median 4 years) presented over 38 consecutive months with V3 VAD and underwent digital catheter angiography with provocative passive bilateral neck rotation.

Results—

VAD were bilateral in 2 patients and unilateral in 5. Provocative digital catheter angiography showed dynamic V3 compression in 6 of 9 dissections, most pronounced or seen only with head rotation to the contralateral side. Two patients had VAD without dynamic compression; both returned 4 months later with a new dissection in a previously normal VA and worsening VAD in 1 patient each. Dynamic compression was also seen in 2 nondissected VA. Surgical management was C1/2 posterior fusion in 5 of 7 patients; 1 underwent unilateral C2 decompression with recurrent VAD and was subsequently fused.

Conclusions—

The association of dynamic VA compression and VAD at the same level suggests that the compression may contribute to the VAD. However, as dynamic compression was observed in nondissected VA and some VAD were not associated with dynamic compression, VAD may be multifactorial.

Bow hunter's syndrome revisited: 2 new cases and literature review of 124 cases

Rotational occlusion of the vertebral artery (VA), or bow hunter's syndrome, is a rare yet surgically treatable cause of vertebrobasilar insufficiency. The underlying pathology is dynamic stenosis of the VA by osteophytes, fibrous bands, or lateral disc herniation with neck rotation or extension. The authors present 2 previously unreported cases of bow hunter's syndrome and summarize 124 cases identified in a literature review. Both patients in the new cases were treated by VA decompression and fusion of the subaxial spine. Each had > 50% occlusion of the left VA at the point of entry into the transverse foramen with a contralateral VA that ended in the posterior inferior cerebellar artery. Analyzing data from 126 cases (the 2 new cases in addition to the previously published 124), the authors report that stenosis was noted within V1 in 4% of cases, in V2 in 58%, in V3 in 36%, and distal to C-1 in 2%. Patients presented in the 5th to 7th decade of life and were more often male than female. The stenotic area was decompressed in 85 (73%) of the 116 patients for whom the type of treatment was reported (V1, 4 [80%] of 5; V2, 52 [83%] of 63; V3/V4, 29 [60%] of 48). Less commonly, fusion or combined decompression and fusion was used (V2, 7 [11%] of 63; V3/V4, 14 [29%] of 48). Most patients reported complete resolution of symptoms. The authors conclude that patients with bow hunter's syndrome classically have an impaired collateral blood flow to the brainstem. This condition carries an excellent prognosis with decompression, fusion, or combined surgery, and individual patient characteristics should guide the choice of therapy.

Surgical decompression coupled with diagnostic dynamic intraoperative angiography for bow hunter's syndrome

Background:

Bow hunter's syndrome, also known as rotational vertebrobasilar insufficiency, arises from mechanical compression of the vertebral artery during the neck rotation. Surgical options have been the mainstay treatment of choice. Postoperative imaging is typically used to assess adequate decompression. On the other hand, intraoperative assessment of decompression has been rarely reported.

Case Description:

A 52-year-old male began to see “black spots,” and experienced presyncope whenever he rotated his head toward the right. The patient ultimately underwent a dynamic diagnostic cerebral angiogram, which revealed a dominant right vertebral artery and complete proximal occlusion of the right vertebral artery with the head rotated toward the right. Subsequently, the patient underwent an anterior transcervical approach to the right C6/C7 transverse process. The bone removal occurred along with the anterior wall of the C6 foramen transversarium, followed by the upper portion of the anterior C6 body medially, and the transverse process of C6 laterally. An oblique osseofibrous band was noted to extend across the vertebral artery; it was dissected and severed. An intraoperative cerebral angiogram confirmed no existing compression of the vertebral artery with the head rotated toward the right. The patient recovered from surgery without issues; he denied recurrence of preoperative symptoms at follow-up.

Conclusions:

The authors report the third instance where intraoperative dynamic angiography was employed with good outcomes. Although intraoperative cerebral angiography is an invasive procedure, which prompts additional risks, the authors believe the modality affords better, real-time visualization of the vertebral artery, allowing for assessment of the adequacy of the decompression. This advantage may reduce the probability for a second procedure, which has its own set of risks, and may counteract the risks involved with intraoperative dynamic angiography.

Bow hunter's syndrome secondary to bilateral dynamic vertebral artery compression

Bow hunter's syndrome is a condition in which vertebrobasilar insufficiency is resultant from head rotation, clinically manifested by presyncopal sensation, syncope, dizziness, and nausea. It is usually diagnosed clinically, with supporting vascular imaging demonstrating an occluded or at the very least compromised unilateral vertebral artery, while the dominant vertebral artery remains patent in the neutral position. Dynamic imaging is utilized to confirm the rotational compression of the dominant vertebral artery. We present the rare case of a patient with typical Bow hunter's symptoms, bilaterally patent vertebral arteries on neutral imaging, and bilateral compromise with head rotation. Our patient underwent posterior decompression of the culprit atlanto-axial transverse foramen and subaxial cervical fusion, with resolution of his symptoms. Our patient exemplifies the possibility of bilateral dynamic vertebral artery occlusion. We show that Bow hunter's syndrome cannot be ruled out in the setting of bilaterally patent vertebral arteries on neutral imaging and that severe cervical spondylosis should impart further clinical suspicion of this unusual phenomenon.

Quantifying sulcal and gyral topography in relation to deep seated and ventricular lesions: cadaveric study for basing surgical approaches and review of literature

OBJECTIVE

Numerical implication of sulcal and gyral topography for surgical approaches has not been studied.

METHODS

Percentage gain of distance using sulci as compared to that of gyri was calculated by measuring distances toward the ventricles in 15 hemispheres.

RESULTS

Superior frontal sulcus was closest proving greater than 50% gain in distance compared to superior frontal gyrus; inferior temporal sulcus provided greater gain in the temporal lobe.

CONCLUSION

Sulci provide upto 58% distance gain. For trans-gyral approaches, MFG and ITG were found closer to the respective ventricular area.

Rotational vertebral artery occlusion secondary to adjacent-level degeneration following anterior cervical discectomy and fusion

Rotational vertebral artery occlusion (RVAO), or bow hunter's syndrome, most often occurs at the C1-2 level on physiological head rotation. It presents with symptoms of vertebrobasilar insufficiency (VBI). Several previously published studies have reported on subaxial sites of vertebral artery (VA) compression by head rotation. The authors report a case of subaxial spine RVAO due to adjacent-segment degeneration. A 52-year-old man presented with dizziness when rotating his head to the left. Twenty years earlier, he had undergone a C4-5 anterior cervical discectomy and fusion (ACDF) for a herniated disc. Imaging studies including a dynamic CT angiography and dynamic catheter angiography revealed occlusion of the left VA at the C3-4 level when the patient turned his head to the left, in the setting of an aberrant vertebrobasilar system. Successful treatment was achieved by surgical decompression of the left VA and C3-4 ACDF. Expedited diagnosis and treatment are dependent on the recognition of this unusual manifestation of RVAO, especially when patients present with nonspecific symptoms of VBI.

Simultaneous bilateral stenosis of the vertebral arteries treated by unilateral decompression: a case report

A 56-year-old man presented with a 3-month history of progressive dizziness. His dizziness was aggravated when his head was rotated to the right side. Diagnostic angiography showed that a normal right-sided vertebral artery in the neutral position became an abnormal vertebral artery with two stenotic lesions at the C3-4 and C5-6 levels when the patient's head was turned to the right. A normal left-sided vertebral artery also showed a stenotic lesion at the C2 level when the patient's head was turned right. The axial dimensions of the bilateral vertebral arteries were similar. The patient was successfully treated with decompression of only one level (C5-6). We conclude that if a bilateral stenosis is found upon one directional head rotation and the bilateral vertebral arteries are similarly sized, a one-sided treatment may suffice.

Utility of intraoperative angiography during subaxial foramen transversarium decompression for bow hunter's syndrome

Bow hunter's syndrome is an uncommon cause of vertebrobasilar insufficiency resulting from rotational compression of the extracranial vertebral artery. While positional compression of any portion of the extracranial vertebral artery has been reported to result in bow hunter's syndrome, the most common site of compression is the V2 segment as it passes through the foramen transversarium of the subaxial cervical spine. A 43-year-old woman presented with increasingly frequent pre-syncopal and syncopal episodes upon leftward head rotation. Pre-operative angiographic studies with the neck rotated to the left demonstrated occlusion of the left vertebral artery by a C4-5 osteophyte arising from the C4 uncinate process. The patient underwent microsurgical decompression of the vertebral artery at C4-5 through a standard anterior transcervical retropharyngeal approach. Selective vertebral artery intraoperative angiography performed with the head passively rotated to the left before and after left vertebral artery decompression showed marked improvement in the luminal diameter and blood flow. The patient's symptoms resolved post-operatively. This case illustrates the second instance of intraoperative angiography used to confirm adequate vertebral artery decompression for bow hunter's syndrome. Intraoperative angiography can be safely used to decrease the extent of vertebral artery decompression in order to minimize the risk of operative complications.

Rotational vertebral artery occlusion: mechanisms and long-term outcome

BACKGROUND AND PURPOSE

To elucidate the mechanisms and prognosis of rotational vertebral artery occlusion (RVAO).

METHODS

We analyzed clinical and radiological characteristics, patterns of induced nystagmus, and outcome in 21 patients (13 men, aged 29-77 years) with RVAO documented by dynamic cerebral angiography during an 8-year period at 3 University Hospitals in Korea. The follow-up periods ranged from 5 to 91 months (median, 37.5 months). Most patients (n=19; 90.5%) received conservative treatments.

RESULTS

All the patients developed vertigo accompanied by tinnitus (38%), fainting (24%), or blurred vision (19%). Only 12 (57.1%) patients showed the typical pattern of RVAO during dynamic cerebral angiography, a compression of the dominant vertebral artery at the C1-2 level during contralateral head rotation. The induced nystagmus was mostly downbeat with horizontal and torsional components beating toward the compressed vertebral artery side. None of the patients with conservative treatments developed posterior circulation stroke, and 4 of them (21.1%) showed resolution of symptoms during the follow-ups.

CONCLUSIONS

RVAO has various patterns of vertebral artery compression, and favorable long-term outcome with conservative treatments. In most patients with RVAO, the symptoms may be ascribed to asymmetrical excitation of the bilateral labyrinth induced by transient ischemia or by disinhibition from inferior cerebellar hypoperfusion. Conservative management might be considered as the first-line treatment of RVAO.

Rare case of bilateral vertebral artery stenosis caused by C4-5 spondylotic changes manifesting with bilateral bow hunter's syndrome

BACKGROUND

Rotational vertebral artery occlusion syndrome refers to vertebrobasilar insufficiency as a result of mechanical occlusion or stenosis of the vertebral artery by head rotation. In most cases, symptoms are produced on extension or rotation to one side. No case of bow hunter's syndrome with bilateral presentation at the C4 level has yet been reported.

CASE DESCRIPTION

A 54-year-old man presented with symptomatic bilateral bow hunter's syndrome induced by head rotation. The patient complained of intermittent dizziness, episodes of double vision, nonpulsatile tinnitus, and headaches indicative of vertebral artery insufficiency with exacerbation of symptoms on rotation of his head to either side. Computed tomography angiography showed bilateral vertebral artery stenosis, and dynamic cerebral angiography revealed bilateral rotational vertebral artery occlusion, with compression of the ipsilateral vertebral artery on head rotation to either side. Bilateral surgical decompression at C4-5 with anterior cervical diskectomy and fusion with a plate was performed.

CONCLUSIONS

Bony obstruction of the vertebral artery on head rotation tends to occur at levels C4 and below, affecting the ipsilateral side. In this rare case, symptomatic bilateral vertebral artery stenosis occurred as a result of bony compression and was symptomatic on head rotation both to the right and to the left. This stenosis was improved with anterior decompression bilaterally, and no further events occurred postoperatively.

Bow-hunter's syndrome caused by dynamic vertebral artery stenosis at the cranio-cervical junction--a management algorithm based on a systematic review and a clinical series

Bow hunter's syndrome (BHS) is defined as symptomatic, vertebro-basilar insufficiency caused by mechanical occlusion of the vertebral artery (VA) at the atlanto-axial level during head rotation. In the literature, about 40 cases have been reported. However, due to the rarity of this pathology, there are no guidelines for diagnosis and treatment. Conservative, surgical, and endovascular concepts have been proposed. In order to work out an algorithm, we performed a systematic review of the literature and a retrospective analysis of patients, which have been treated in our institutions over the last decade. The clinical series was comprised of five patients. The symptoms ranged from transient vertigo to posterior circulation stroke. Diagnosis was established by dynamic angiography. In all patients, the VA was decompressed; one patient required additional fusion. The clinical and radiological results were good, and the treatment-related morbidity was low. The literature review demonstrated that Bow hunter's syndrome is a rare pathology but associated with a pathognomonic and serious clinical presentation. The gold standard of diagnosis is dynamic angiography, and patients were well managed with tailored vertebral artery decompression. By this management, clinical and radiological results were excellent and the treatment-related morbidity was low.

Origin of isolated vertigo in rotational vertebral artery syndrome

Rotational vertebral artery syndrome (RVAS) is characterized by recurrent attacks of paroxysmal vertigo, nystagmus, and ataxia induced by head rotation. Although recent report has described the RVAS as an important but unrecognized cause of isolated vascular vertigo, the locus of injury site responsible for isolated vertigo in RVAS is still unclear. We report here two patients with RVAS who had a stereotypic clinical presentation characterized by recurrent attacks of isolated vertigo induced by head rotation. The pattern of nystagmus observed in our patients with RVAS can be best explained by the stimulation of the vestibular labyrinth bilaterally or unilaterally. In RVAS, the isolated vertigo may occur due to transient ischemia of the superior vestibular labyrinth. RAVS should be considered in the differential diagnosis of positional vertigo, especially when vertigo is developed while sitting or standing position.

Vertigo is associated with advanced degenerative changes in patients with cervical spondylosis

Since vascular risk factors that predispose to vertebrobasilar ischemia are common findings in elderly, cervical spondylosis-which is also common in such age group-as a cause of vertigo is sometimes considered as a myth. The purpose of this study is to investigate the effect of cervical spondylosis on blood flow velocity of VAs during cervical rotation and to identify the possible association of vertigo with the decreased blood flow velocity through VAs during head rotation in these patients. The incidence of cervical spondylosis was estimated in patients with and without vertigo. Patients with vertigo proved to have spondylosis are further compared with patients having spondylosis but not complaining of vertigo and patients who neither have spondylosis nor complain of vertigo who served as controls. Plain cervical radiography was used to evaluate cervical degenerative changes using cervical degenerative index. Color duplex sonography was used to measure vertebral artery blood flow with the cervical spine in the neutral position then with 60° rotation and 30° extension to measure the opposite vertebral artery. A significantly higher prevalence of cervical spondylosis was found among patients complaining of vertigo than those in non-vertigo group (71.4% vs. 32.9%, respectively). Furthermore, among patients with cervical spondylosis, patients having vertigo showed significantly more evident degenerative changes (P = 0.003). Despite Doppler ultrasound examination with head in neutral position was similar in all groups; cervical spondylosis patients with vertigo had statistically significant lower blood flow parameters with contralateral head rotation in the left and right vertebral arteries than cervical spondylosis patients without vertigo and controls. The decreased vertebral artery blood flow that occurs with cervical rotation can be observed in patients with cervical spondylosis. In patients with high-grade cervical spondylosis with more extensive osteophyte formation, the decreased blood flow becomes prominent and symptomatic presenting as vertigo.

Rotational vertebral artery occlusion-series of 9 cases

BACKGROUND

Rotational vertebral artery syndrome (RVAS) is a rare entity about which previously published studies are mostly limited to individual case reports.

OBJECTIVE

To report our decade-long experience with this syndrome in 9 patients with compression ranging from the occiput to C6.

METHODS

We utilized a posterior approach for lesions rostral to C4 and an anterior approach for lesions at or caudal to C4. Furthermore, we demonstrated the feasibility and efficacy of a minimally invasive posterior cervical approach. Patient profile, operative indications, surgical approach, operative findings, complications, and long-term follow-up were reviewed and discussed.

RESULTS

Average follow-up was 47 months. All procedures provided excellent outcomes by Glasgow Outcome Scale scores. The anterior approach had significantly less blood loss (187.5 mL vs 450 mL, P = .00016) and shorter hospitalization length (2 days vs 4.5 days; P = .0001) compared with the far-lateral approach. There was one complication of cervical instability in the far-lateral approach cohort. As an alternative to the far-lateral surgery, a minimally invasive approach resulted in shorter hospitalization (2 days) and less blood loss (10 mL) while avoiding the complication of cervical instability.

CONCLUSION

We demonstrated the safety, efficacy, and durability of 3 surgical approaches for RVAS. Proper examination, preoperative imaging, and surgical planning were necessary for a satisfactory outcome.

Two case presentations and surgical management of Bow Hunter's syndrome associated with bony abnormalities of the C7 vertebra

Bow Hunter's syndrome is a condition in which patients experience vertebrobasilar symptoms on head turn. It may be a consequence of intrinsic factors such as atherosclerosis, or it may be secondary to mechanical compression. Most commonly, this occurs at the level of C2 or above. We present two rare cases of Bow Hunter's syndrome secondary to mechanical compression at the level of C7. Discussed are the anatomic conditions leading to this syndrome in these two patients, the methodology for confirming the diagnosis, and the successful management by partial resection of the transverse processes compressing the vertebral arteries.

Rotational vertebral artery occlusion in a child with multiple strokes: a case-based update

INTRODUCTION

Rotational vertebral artery occlusion (RVAO), sometimes known as "Bow hunter syndrome," is an important and diagnostically challenging cause of posterior circulation stroke in children. It is caused by impingement of osseous and/or ligamentous structures on the vertebral artery.

DISCUSSION

We review the differential diagnosis and recommended workup for posterior circulation stroke in children. The anatomical cause for pediatric RVAO is most commonly an anomalous bone formation of the rostral vertebral column. Many bony anomalies have been associated with RVAO, including the "ponticulus posticus," a common anomaly of the C1 vertebrae. The definitive diagnosis of RVAO is made with dynamic angiography, and surgical decompression of the vertebral artery prevents recurrent strokes.

ILLUSTRATIVE CASE

We report a 15-year-old boy with recurrent posterior circulation ischemic strokes caused by an anomalous ossification of the C1 vertebrae. Three-dimensional (3D) and multiplanar reconstructed CT images showed the anomalous C1 ossification, and cervicocerebral digital subtraction angiography (DSA) revealed an associated vertebral artery (VA) dissection. The patient was initially managed by head immobilization in a hard collar and anticoagulation for 3 months. After healing of the dissection that was confirmed angiographically, dynamic DSA demonstrated reversible occlusion of the VA during contralateral head turn. Surgical decompression of the VA was performed and confirmed by intra-operative DSA with head turning.

CONCLUSIONS

RVAO is an important diagnosis in children with posterior circulation stroke. Our case demonstrates the need for high clinical suspicion and careful analysis of 3D cervical spine CT images in children with posterior circulation stroke.

Enhanced external counterpulsation and traction therapy ameliorates rotational vertebral artery flow insufficiency resulting from cervical spondylosis

STUDY DESIGN

Clinical trial of patients with rotational vertebrobasilar insufficiency (VBI) resulting from cervical spondylosis.

OBJECTIVE

To investigate the effectiveness of enhanced external counterpulsation (EECP) and traction therapy for these patients.

SUMMARY OF BACKGROUND DATA

EECP would reduce arterial stiffness and vascular resistance, and increase regional blood flow of vertebral arteries, thus may ameliorate symptoms in these patients.

METHODS

One hundred sixty-three patients who were clinically suspected rotational VBI caused by cervical spondylosis were enrolled in this study. They were randomly allocated into 3 groups: EECP + traction, EECP, and traction group. All patients and 50 healthy volunteers received transcranial color Doppler examination of the vertebral artery and basilar artery in both a neutral cervical spine position and a rotational position.

RESULTS

Within 3 days after treatment, 47 (84%) patients in EECP + traction group, 32 (61%) patients in EECP group, and 8 (15%) patients in traction group achieved successful outcomes, while at 3 months' follow-up, 45 (80%) patients in EECP + traction group, 34 (64%) in EECP group, and 3 (6%) in traction group achieved successful outcomes. With head rotation, the percentage of reduction of blood flow velocities of the vertebrobasilar artery (VBA) in patients was much greater than that of the healthy volunteers (P < 0.01). After treatment, rotational blood flow velocity reduction percentage of VBA in each treatment group was much lower than that of each group before treatment. EECP + traction group experienced the greatest decrease of rotational blood flow velocity reduction percentage of VBA, while EECP group experienced second greatest.

CONCLUSION

EECP and traction therapy can relieve the symptoms of rotational VBI, improve the rotational reduction of vertebrobasilar blood flow, and reduce the increased arterial impedance.

Microsurgical anatomy of the temporal stem: clinical relevance and correlations with diffusion tensor imaging fiber tracking

Object

The authors used a fiber dissection technique to describe the temporal stem and explain the tendency of malignant tumors to spread within both the frontal and temporal lobes. The authors focused on the morphological characteristics and course of various fasciculi of the temporal stem, including the uncinate fascicle, occipitofrontal fascicle, anterior commissure, loop of the optic radiations (Meyer loop), and the ansa peduncularis.

Methods

Eight previously frozen, formalin-fixed human brains were dissected under an operating microscope using the fiber dissection technique described by Klingler. Lateral, inferior, and medial approaches were made. Cross-sectional 3D MR images obtained in 10 patients without brain lesions demonstrated that fibers of the temporal stem, which were intermingled together in various ways, curved laterally within the basal forebrain. Various pathological entities affecting the temporal stem are described and discussed.

Results

The uncinate fascicle has 3 portions: a ventral extension, an intermediary segment called the isthmus, and a dorsal segment. The inferior occipitofrontal fasciculus is a layer of more superficial white matter that appeared to be superior to the uncinate fasciculus. A short ventral portion of the radiations of the corpus callosum was sometimes noted to run ventrally to enter the temporal stem and to reach both temporal lobes.

Conclusions

To the authors' knowledge, a detailed anatomy of the temporal stem has not been previously described in the literature. The unique anatomy of the temporal stem provides a route for tumor spread between the frontal and temporal lobes.

Minimally invasive decompression of a suboccipital osseous prominence causing rotational vertebral artery occlusion. Case report

Surgical decompression of the vertebral artery (VA) between the suboccipital area and C-1 is typically performed via a large midline incision or a far-lateral approach. Such traditional open approaches are often associated with significant muscle dissection and blood loss. In this case, a 12-year-old boy suffered a stroke related to a VA rotational occlusion (bow hunter syndrome) and dissection due to a prominent suboccipital bone mass. Successful decompression of the VA was performed via a minimally invasive 22-mm tubular retractor. This is the first reported case report of a minimally invasive decompression of the VA between the skull base and C-1.

Rotational vertebrobasilar ischemia due to vertebral artery dynamic stenoses complicated by an ostial atherosclerotic stenosis

Abstract

We describe a patient with rotational vertebrobasilar ischemia (RVBI) due to vertebral artery (VA) compressive stenoses during neck rotation, complicated by an ostial atherosclerotic stenosis (OAS). Referred for ‘near-syncopal spells’, inquiry revealed a symptom-complex consistent with vertebrobasilar transient ischemic attacks (TIAs) provoked by head rotation. VA dynamic angiography with imaging via prevertebral subclavian injections in neck-rotated positions while reproducing symptoms, demonstrated two compressive stenoses not present in the neck-neutral position, establishing the diagnosis of RVBI due to CT-demonstrated cervical spondylosis. There was an occluded contralateral VA, isolated posterior circulation, and absent vertebral collateral flow. Disabling symptoms persisted despite using a cervical collar. Surgical decompression of the dynamic stenoses would not address the OAS, was considered high risk, and absence of a suitable donor artery precluded distal VA reconstruction. RVBI resolved with ostial stent placement by improving perfusion pressure across the compressive stenoses. To our knowledge, this is the first report of RVBI in which the affected VA had an obstructive atherosclerotic stenosis in addition to the characteristic rotation-induced dynamic stenoses, and the first report of stent placement in the culprit artery to treat this disorder. Diagnosis depends on recognizing the association of symptoms with positional neck changes and VA dynamic angiography demonstrating the compressive stenosis while reproducing symptoms. This case illustrates the management complexities when there are coexisting abnormalities, emphasizing the need to individualize treatment. RVBI is a potentially correctable cause of TIAs and particularly relevant due to the aging population which has a significant incidence of both degenerative cervical and atherosclerotic cerebrovascular disease.

Cervicogenic dizziness as a cause of vertigo while swimming: an unusual case report

We present the unusual case of a competitive swimmer with cervicogenic dizziness manifesting as vertigo while she was surface swimming. This patient complained of brief and episodic room-spinning vertigo consistently associated with swimming the freestyle stroke and was referred to an otolaryngology clinic for evaluation. She did not have significant complaints of neck pain while swimming. Her history, examination findings, laboratory study results, differential diagnoses, and treatment are discussed in detail. A succinct overview of cervicogenic dizziness--a controversial diagnosis often overlooked by otolaryngologists-is also provided.