Anterior cerebral artery syndrome

Overview

Anterior Cerebral Artery (ACA) Syndrome is a neurological condition that occurs when there is an interruption in blood flow through the anterior cerebral artery, one of the major arteries supplying the brain. The ACA primarily supplies the medial portions of the frontal lobes and superior medial parietal lobes. Ischemia or infarction in this territory can lead to characteristic neurological deficits, especially affecting the lower limbs and certain cognitive and behavioral functions.

ACA syndrome is less common than strokes involving the middle cerebral artery but is important to recognize due to its distinct clinical features and implications.

Causes

The most common cause of anterior cerebral artery syndrome is a stroke due to ischemia, typically from:

• Thrombotic occlusion: A blood clot forming within the artery itself

• Embolism: A clot or debris from elsewhere (e.g., heart or carotid arteries) lodging in the ACA

• Vasospasm: Often after subarachnoid hemorrhage

• Aneurysm rupture or trauma: Rarely, bleeding may compress the ACA

Other risk factors for ACA syndrome include hypertension, atherosclerosis, atrial fibrillation, smoking, diabetes, and hyperlipidemia.

Symptoms

The symptoms of ACA syndrome reflect dysfunction in the areas of the brain supplied by the anterior cerebral artery. Common signs include:

Motor and Sensory Deficits:

• Contralateral (opposite side) weakness or paralysis, especially of the lower limb (leg more than arm or face)

• Contralateral sensory loss in the leg

Frontal Lobe Involvement:

• Apraxia (difficulty with motor planning)

• Abulia (lack of initiative or motivation)

• Mutism or speech disturbance

• Personality changes or emotional disturbances

Other Features:

• Urinary incontinence (due to involvement of the medial frontal micturition center)

• Gait apraxia or difficulty walking

• Alien limb phenomenon (rare)

Diagnosis

Diagnosis of ACA syndrome is based on clinical presentation and neuroimaging studies:

• Neurological examination: Reveals characteristic motor and behavioral findings

• CT scan or MRI of the brain: Identifies infarction or ischemia in the ACA territory

• CT angiography or MR angiography: To visualize occlusion or stenosis of the anterior cerebral artery

• Carotid Doppler ultrasound: Evaluates for upstream vascular sources of emboli

• Cardiac evaluation: May include ECG or echocardiography to assess for embolic sources

Treatment

Treatment for ACA syndrome focuses on restoring blood flow, preventing further strokes, and managing symptoms. This includes:

Acute Stroke Management:

• Intravenous thrombolysis (tPA): If within the appropriate time window (typically 4.5 hours from symptom onset)

• Endovascular thrombectomy: In select cases with large vessel occlusion

Secondary Prevention:

• Antiplatelet agents (e.g., aspirin, clopidogrel)

• Anticoagulation if the cause is cardioembolic (e.g., atrial fibrillation)

• Management of risk factors (blood pressure, cholesterol, diabetes)

• Lifestyle changes (smoking cessation, diet, exercise)

Rehabilitation:

• Physical therapy for motor recovery, especially lower limb function

• Occupational and speech therapy as needed

• Neuropsychological support for behavioral and cognitive symptoms

Prognosis

The prognosis of anterior cerebral artery syndrome depends on the severity and extent of the infarction, as well as the speed of intervention. Many patients recover with supportive care and rehabilitation, particularly if the infarct is small or treatment is initiated early. However, persistent deficits, especially in motor function of the lower limbs and behavioral control, may occur in larger strokes or if care is delayed.

Long-term outcomes improve significantly with comprehensive stroke rehabilitation and management of underlying risk factors.