Basics
Description
- Vertebrobasilar (VB) vascular system feeds the posterior region of
the brain, which includes the brainstem, cerebellum, and inner ear - 2 vertebral arteries (VA) derive from subclavian arteries and give rise to the anterior spinal artery and then join to form the basilar artery
- Arteries supplying the brainstem and cerebellum originate from the VB system before it branches into the 2 posterior cerebral arteries (PCA), such that a wide variety of focal neurological deficits arise from VB circulatory dysfunction
- Vertebrobasilar insufficiency (VBI) results in inadequate perfusion of VB arterial circulation from thrombotic, embolic, or low-flow states
Etiology
- Mechanism:
- Thrombosis:
- VB ischemia due to underlying VB atherosclerosis and clot formation
- Embolus:
- VB ischemia due to embolization of clot from proximal location
- Low-flow states:
- Hypoperfusion of VB system from systemic (e.g., cardiogenic shock) or localized (e.g., subclavian steal) reduction in blood flow
- Less common etiologies:
- Fibromuscular dysplasia
- Hypercoagulable states
- Ischemic mechanisms causing VB insufficiency can herald and lead to VB territory infarcts
- Severe episodes of VB hypoperfusion or loss of circulation can lead to:
- "Locked-in " syndrome:
- Quadriplegia (eyelid or eye movement only) with intact consciousness
- "Top-of-basilar " syndrome:
- Pontine and cerebellar dysfunction with diminished level of consciousness
Diagnosis
Signs and Symptoms
All history and physical exam items may present intermittently
History
- Dizziness/vertigo ( "mild, " "nonviolent " ; may be isolated finding)
- Onset usually abrupt and spontaneous rather than position induced
- May have a flurry of spells within a few weeks time
- "Drop attack "
- Headache
- Nausea/vomiting
- Paresis/paresthesia
- Seizure
- Syncope
- Neurologic symptoms localizing to the posterior circulation:
- Visual changes (double vision, blurry vision, blindness)
- Numbness of the face or extremities
- Weakness in arms or legs
- Clumsiness in arms or legs
- Confusion or loss of consciousness
- Difficulty with speech
- Difficulty swallowing
- Pain in neck or shoulder
Physical Exam
- Brainstem:
- "Crossed " findings (i.e., ipsilateral facial and contralateral body deficits)
- Altered mental status or responsiveness
- Decreased respiratory drive
- Horners syndrome (enophthalmos, ptosis, miosis, anhidrosis)
- Internuclear ophthalmoplegia
- Nystagmus (especially nonfatigable, vertical/rotatory)
- Paresis/paresthesias
- Cranial nerves:
- Extraocular muscle paresis (e.g., diplopia)
- Pupillary abnormalities
- Facial paresthesia
- Facial muscle paresis
- Hearing abnormalities
- Dysphagia
- Dysarthria
- Cerebral cortex (PCA circulation):
- Visual disturbances (e.g., homonymous hemianopsia)
- Cerebellar:
- Ataxia
- Dysmetria
- Gait abnormality
- Cardiovascular:
- Carotid/VA bruit
- Irregular/asymmetric/weak pulses
Essential Workup
- Emergent head CT (noncontrast) to evaluate for hemorrhage (parenchymal, subarachnoid, traumatic), large acute infarcts, prior pathology
- Thorough neurologic and cardiac exam
- Neurology consultation
- 12-lead ECG for arrhythmias and myocardial ischemia
- CTA and/or MRA for imaging of the posterior circulation
Diagnosis Tests & Interpretation
Lab
- CBC:
- Anemia, thrombocytopenia; polycythemia, thrombocytosis
- Coagulation studies (PT/PTT):
- Hypo- and hypercoagulable states; baseline values for anticoagulant and fibrinolytic therapies
- Electrolytes, BUN/creatinine, glucose
- Cardiac markers for concurrent myocardial ischemia
- Urinalysis
- ESR for systemic vasculitides
- Rapid plasma reagin
- Thyroid stimulating hormone
- Lipid profile
Imaging
- Emergent head CT (noncontrast)
- Head and neck CT angiogram (CTA) for evaluation of posterior circulation and possible acute vascular intervention
- Chest radiograph; consider chest CTA for cardiopulmonary and great vessel pathology
- MRI/magnetic resonance angiography (MRA) for improved characterization of ischemic lesion and cerebrovascular circulation (e.g., congenital VB anomalies, exclusion of VA dissection)
- Echocardiography for intracardiac embolic source
- Cervical Doppler US
- Transcranial Doppler US
Diagnostic Procedures/Surgery
- Neuroangiography for diagnosis
- Directed intra-arterial thrombolytic therapy/angioplasty/stenting/embolectomy are still under investigation)
Differential Diagnosis
- CNS:
- CVA (hemorrhagic or ischemic):
- Cerebral
- Cerebellar
- Brainstem
- Multiple sclerosis
- Migraine syndromes
- Seizure (focal)
- Traumatic injury/postconcussive
- Tumor
- Vascular malformation hemorrhage (arteriovenous malformation, subarachnoid)
- Brainstem herniation
- Peripheral nervous system:
- Ear, nose, throat:
- Cerebellopontine angle tumor
- Ear canal pathology (foreign body, tumor)
- Labyrinthitis/otitis media
- Meni ¨re disease
- Benign paroxysmal positional vertigo
- Cardiovascular:
- Arrhythmia
- Myocardial ischemia/infarct
- Aneurysm/dissection (VA, basilar artery, subclavian artery, aorta)
- Hypovolemia
- Vasculitides
- Endocrine:
- Adrenal insufficiency
- Hypothyroidism
- Hematologic:
- Anemia
- Coagulopathy/hypercoagulable state
- Infectious:
- Encephalitis/meningitis
- Otitis media/mastoiditis
- Septic shock
- Syphilis
- Metabolic:
- Hypoglycemia; hyperglycemia
- Electrolyte imbalance
- Toxicologic:
- Ataxia: Alcohols, lithium, phenytoin
- Salicylism
- Serotonin syndrome
- Iatrogenic
Treatment
Pre-Hospital
- ABCs
- Fingerstick glucose measurement
- Naloxone if indicated
- Notification:
- Urgent contact with receiving facility if airway compromise or hemodynamic instability
Initial Stabilization/Therapy
- ABCs
- Administer oxygen
- Place on cardiac monitor and pulse oximeter
- Establish IV access with 0.9% normal saline
Ed Treatment/Procedures
- Cerebrovascular perfusion management:
- Supportive care
- Supine position
- Antiplatelet agent if no hemorrhagic source
- Anticoagulation:
- Consider in consultation with neurology if significant risk factors for embolic source, unstable or progressive ischemic symptoms
- Ideal BP targets not well defined; maintain BPs within patients expected range (i.e., account for chronic hypertension)
- If hypotensive: Fluid resuscitation; vasopressors or blood as indicated
- If hypertensive: Administer titratable antihypertensive medications for severe HTN (mean arterial pressure >140 mm Hg, systolic BP >220 mm Hg, diastolic BP >130 mm Hg) or hemorrhage/aneurysm/dissection, myocardial or other end-organ dysfunction
- GI:
- NPO (rehydrate with IV fluids; maintain normoglycemia)
- Antiemetics
- Consultation:
- Neurology
- Vascular interventional radiology for neuroangiography
Medication
- Aspirin: 325 mg PO
- Clopidogrel: 75 mg PO
- Warfarin (dose for atrial fibrillation): 2 " 5 mg PO loading dose
- Heparin (dose for atrial fibrillation): 50 " 60 U/kg IV bolus, then IV infusion at 12 " 18 U/kg for target PTT 50 " 70 sec
- Labetalol: 20 " 40 mg IV over 2 min, then 40 " 80 mg IV q10min (max. 300 mg IV)
- Meclizine: 25 mg PO q8 " 12h
- Naloxone: 0.4 " 2 mg IM/IV q2 " 3min PRN
- Nitroprusside: 0.25 " 10 Όg/kg/min IV infusion (max. 10 Όg/kg/min)
- Ondansetron: 4 mg IV
- Promethazine: 12.5 " 25 mg PO/PR/IV q6 " 8h
- Ticlopidine: 250 mg PO BID
Follow-Up
Disposition
Admission Criteria
- ICU admission for:
- Altered mental status with airway issues
- Concurrent hemodynamic instability
- Malignant cardiac arrhythmias
- Admit to hospital to identify or exclude etiologies of VB ischemia and to prevent recurrence or progression to VB circulation cerebrovascular accident, especially in the following populations:
- Elderly
- Inability to ambulate
- Inability to tolerate oral intake
- Inability to arrange (expeditious) outpatient follow-up
- New or changing neurologic deficit
- Persistent dizziness
- Syncope
- Vascular risk factors
Discharge Criteria
- Consider discharge with outpatient follow-up in populations with the following:
- None of above indications to consider admission
- Alternative explanation for symptomatology
Issues for Referral
- VB ischemia-related referrals as arranged/recommended by admitting team
- Arrange expeditious referrals with PCP or appropriate specialist (e.g., neurology, otorhinolaryngology, vascular surgery) as indicated for alternative explanation for symptomatology
Follow-Up Recommendations
- VB ischemia-related follow-up as arranged/recommended by admitting team
- Urgency and nature of other follow-up as determined by alternative explanation of symptomatology
Pearls and Pitfalls
- Always consider VB insufficiency for dizziness, vertigo, mental status changes, syncope, and overlapping/atypical neurologic presentations
- VBI more likely to occur in patients with spontaneous vertigo lasting a few minutes with accompanying neurologic symptoms and who have cardiovascular risk factors
- Start antithrombotic/antiembolic treatments for VB insufficiency in the absence of contraindications
Additional Reading
- Ishiyama G, Ishiyama A. Vertebrobasilar infarcts and ischemia. Otolaryngol Clin North Am. 2011;44:415 " 435.
- Love BB, Biller J. Neurovascular system. In: CG Goetz, ed. Textbook of Clinical Neurology. 3rd ed. Philadelphia, PA: Elsevier; 2007:405 " 434.
- Marquardt L,
Kuker W, Chandratheva
A, et al. Incidence and prognosis of > or = 50%
symptomatic vertebral or basilar artery stenosis: Prospective population-based study.
Brain.
2009;132:982 " 988.
- Savitz SI, Caplan LR. Vertebrobasilar disease. N Engl J Med. 2005;352:2618 " 2626.
- Schneider JI, Olshaker JS. Vertigo, vertebrobasilar disease, and posterior circulation ischemic stroke. Emerg Med Clin North Am. 2012;30:681 " 693.
Codes
ICD9
435.3 Vertebrobasilar artery syndrome
ICD10
G45.0 Vertebro-basilar artery syndrome
SNOMED
- 64009001 basilar artery syndrome (disorder)