Top of Basilar Artery Syndrome

Top of Basilar Artery Syndrome is a rare but severe neurological condition resulting from an obstruction at the top of the basilar artery, the main artery supplying blood to the upper part of the brainstem, thalamus, midbrain, and parts of the cerebral cortex. When blood flow is blocked or restricted at this critical juncture, it can lead to a complex array of neurological symptoms due to the affected brain areas.

Causes

The syndrome is typically caused by a blood clot (thrombus) or embolism that lodges in the top of the basilar artery, cutting off blood supply to crucial brain structures. Other causes include atherosclerosis (hardening of the arteries) or vasospasm (narrowing of blood vessels).

Key Symptoms

Since multiple brain areas are impacted, top of basilar artery syndrome presents with a range of symptoms, often affecting consciousness, vision, movement, and sensation:

1. Disturbances of Consciousness:
   • Altered mental state: confusion, lethargy, or even coma due to disruption in the midbrain and thalamic areas that control consciousness.
2. Visual Disturbances:
   • Cortical blindness: loss of vision despite normal eye function.
   • Visual hallucinations: seeing images or shapes that are not present.
   • Oculomotor disturbances: difficulty moving the eyes, double vision, or paralysis of eye movement (due to cranial nerve involvement).
3. Motor and Sensory Symptoms:
   • Quadriplegia: paralysis of all four limbs, often due to involvement of the brainstem or midbrain motor pathways.
   • Ataxia: difficulty with coordination and balance.
   • Hemiparesis or hemiplegia: weakness or paralysis on one side of the body, depending on which areas of the brain are affected.
4. Behavioral and Cognitive Changes:
   • Agitation or abnormal behavior due to thalamic or cortical involvement.
   • Memory problems or difficulty with complex thinking.
5. Other Brainstem-Related Symptoms:
   • Dysarthria: difficulty speaking clearly due to motor control issues.
   • Difficulty swallowing (dysphagia).

Diagnosis

Diagnosis of top of basilar artery syndrome usually involves:

• Imaging studies such as MRI or CT angiography to visualize blood flow and identify the location and cause of the obstruction.
• Neurological exam to assess the extent and type of symptoms.

Treatment

Top of Basilar Artery Syndrome is a medical emergency. Treatment typically aims to restore blood flow and prevent further damage:

1. Thrombolytic Therapy:
   • Intravenous tissue plasminogen activator (tPA) can help dissolve clots, but this must be administered within a narrow time window following the onset of symptoms.
2. Endovascular Procedures:
   • In cases where thrombolytic therapy is not possible or effective, mechanical thrombectomy (removal of the clot) may be performed using catheter-based techniques.
3. Supportive Care and Rehabilitation:
   • Long-term recovery often requires physical therapy, occupational therapy, and speech therapy to help regain lost function.
   • Cognitive and psychological support may also be necessary due to the high impact of the syndrome on brain function.

Prognosis

The prognosis for top of basilar artery syndrome is often poor due to the extensive damage caused by the blockage. However, outcomes vary depending on the promptness of treatment and the extent of brain injury.