Symptoms of Basilar Artery Stroke
Basilar artery stroke presents with a constellation of brainstem and posterior circulation symptoms that are often non-specific and can mimic other conditions, leading to dangerous delays in diagnosis. 1
Common Initial Symptoms
Motor and Speech Manifestations
- Motor deficits are the most frequent initial symptom, occurring in approximately 67-92% of patients, including facial palsies and unilateral extremity weakness 1, 2, 3
- Dysarthria (slurred speech) occurs in approximately 63% of patients and is a late sign of disease progression 2, 3, 4
- Hemiparesis or weakness affecting one side of the body 4
Vestibular and Cerebellar Symptoms
- Vertigo, nausea, and vomiting are extremely common prodromal symptoms occurring in approximately 54% of patients during the 2 weeks before stroke 5, 3
- Dizziness and imbalance are frequently reported 1, 2
- Ataxia (impaired coordination), particularly truncal ataxia, is a hallmark finding 1, 2
Cranial Nerve and Sensory Manifestations
- Visual disturbances including double vision, blurred vision, and visual field defects are early warning signs 2, 3
- Eye movement abnormalities occur in approximately 63% of patients, including nystagmus 1, 3
- Hearing loss may develop 1, 2
- Headache occurs in approximately 42% of patients and is an early sign 5, 3
Altered Consciousness
- Loss of consciousness or altered level of consciousness occurs in approximately 50% of patients 1, 2, 3
- Coma or locked-in syndrome can develop, particularly with proximal basilar occlusions 1
Specific Syndromes by Occlusion Location
Top of Basilar Syndrome
- Somnolence and altered consciousness 1
- Peduncular hallucinosis 1
- Convergence nystagmus and oscillatory eye movements 1
- Vertical gaze paralysis 1
- Skew deviation and retraction/elevation of eyelids 1
Mid-Basilar Occlusions
- Various pontine syndromes with brainstem findings 1
- Lower cranial nerve deficits occur in approximately 63% of patients 3
Proximal Basilar Occlusions
- Locked-in syndrome (tetraplegia with preserved consciousness) 1
- Bilateral extensor plantar responses in approximately 38% of patients 3
Movement Disorders (Basal Ganglia Involvement)
- Dystonia, hypertonia, and rigidity with Parkinsonian characteristics 2
- Tremors 2
- Diminished or absent reflexes in affected limbs 2
Critical Diagnostic Pitfalls
NIHSS Limitations
The National Institutes of Health Stroke Scale (NIHSS) is dangerously inadequate for detecting basilar artery strokes because it emphasizes limb and speech impairments over cranial nerve lesions. 1 Patients with posterior circulation emergent large vessel occlusion can have an NIHSS score of 0, presenting only with headache, vertigo, and nausea. 1, 2
Temporal Pattern Recognition
- Onset is gradual in nearly all patients (92%), with warning signs present for up to 2 months before the final stage in 50% of cases 3
- Only 8% have an acute course without adequate warning signs 3
- Once permanent neurological deficits appear, the final illness is reached within 6 hours in 41%, between 6-24 hours in 32%, and in 2-3 days in 27% 3
- Stuttering or progressive symptoms are particularly common with bilateral vertebral artery occlusions 5
Non-Specific Presentation
Posterior circulation strokes presenting to emergency departments are associated with significant delays in neurology evaluation and door-to-needle time because symptoms mimic other clinical conditions. 1 Physicians must maintain an extremely high index of suspicion even with subtle symptoms. 1, 2
Prognostic Indicators
Poor Outcome Predictors
- Older age 1
- Higher NIHSS score (though NIHSS underestimates severity) 1
- Lack of recanalization 1
- Atrial fibrillation 1
- Intracranial hemorrhage 1
- Posterior circulation ASPECTS ≤8 1
Mortality
Mortality from basilar artery occlusion ranges from 45% to 86%, with good clinical outcomes occurring in only approximately 20% of patients despite advanced care. 1, 2 The condition was historically considered universally fatal. 1