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Vertebrobasilar Insufficiency, Emergency Medicine

Basics

Description

- Embolus: - VB ischemia due to embolization of clot from proximal location

- Less common etiologies: - Fibromuscular dysplasia - Hypercoagulable states

- 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

- 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

- Cerebellar: - Ataxia - Dysmetria - Gait abnormality

- Cardiovascular: - Carotid/VA bruit - Irregular/asymmetric/weak pulses

- 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

- Infectious: - Encephalitis/meningitis - Otitis media/mastoiditis - Septic shock - Syphilis

- Metabolic: - Hypoglycemia; hyperglycemia - Electrolyte imbalance

- Toxicologic: - Ataxia: Alcohols, lithium, phenytoin - Salicylism - Serotonin syndrome - Iatrogenic

- 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

- 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

  • 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 formationEmbolus:VB ischemia due to embolization of clot from proximal locationLow-flow states:Hypoperfusion of VB system from systemic (e.g., cardiogenic shock) or localized (e.g., subclavian steal) reduction in blood flowLess common etiologies:Fibromuscular dysplasiaHypercoagulable 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 extremitiesWeakness in arms or legsClumsiness in arms or legsConfusion or loss of consciousnessDifficulty with speechDifficulty swallowingPain in neck or shoulder

Physical Exam

  • Brainstem: "Crossed " findings (i.e., ipsilateral facial and contralateral body deficits)Altered mental status or responsivenessDecreased respiratory driveHorners syndrome (enophthalmos, ptosis, miosis, anhidrosis)Internuclear ophthalmoplegiaNystagmus (especially nonfatigable, vertical/rotatory)Paresis/paresthesias
  • Cranial nerves:Extraocular muscle paresis (e.g., diplopia)Pupillary abnormalitiesFacial paresthesiaFacial muscle paresisHearing abnormalitiesDysphagiaDysarthria
  • Cerebral cortex (PCA circulation):Visual disturbances (e.g., homonymous hemianopsia)
  • Cerebellar:AtaxiaDysmetriaGait abnormality
  • Cardiovascular:Carotid/VA bruitIrregular/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):CerebralCerebellarBrainstemMultiple sclerosisMigraine syndromesSeizure (focal)Traumatic injury/postconcussiveTumorVascular malformation hemorrhage (arteriovenous malformation, subarachnoid)Brainstem herniation
  • Peripheral nervous system:
  • Ear, nose, throat:Cerebellopontine angle tumorEar canal pathology (foreign body, tumor)Labyrinthitis/otitis mediaMeni ¨re diseaseBenign paroxysmal positional vertigo
  • Cardiovascular:ArrhythmiaMyocardial ischemia/infarctAneurysm/dissection (VA, basilar artery, subclavian artery, aorta)HypovolemiaVasculitides
  • Endocrine:Adrenal insufficiencyHypothyroidism
  • Hematologic:AnemiaCoagulopathy/hypercoagulable state
  • Infectious:Encephalitis/meningitisOtitis media/mastoiditisSeptic shockSyphilis
  • Metabolic:Hypoglycemia; hyperglycemiaElectrolyte imbalance
  • Toxicologic:Ataxia: Alcohols, lithium, phenytoinSalicylismSerotonin syndromeIatrogenic

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 careSupine positionAntiplatelet agent if no hemorrhagic sourceAnticoagulation:Consider in consultation with neurology if significant risk factors for embolic source, unstable or progressive ischemic symptomsIdeal 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:NeurologyVascular 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 issuesConcurrent hemodynamic instabilityMalignant 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:ElderlyInability to ambulateInability to tolerate oral intakeInability to arrange (expeditious) outpatient follow-upNew or changing neurologic deficitPersistent dizzinessSyncopeVascular risk factors

Discharge Criteria

  • Consider discharge with outpatient follow-up in populations with the following:None of above indications to consider admissionAlternative 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)