Anterior cerebral artery syndromes

Motor deficit

Contralateral UMN type weakness of the entire leg is the typical presentation of large ACA infarcts.

Contralateral arm weakness may also be seen when more posterior parts of the ACA territory are involved.

Unusual weakness patterns:

• Ataxia-hemiparesis syndrome
• Pure motor hemiparesis
• Pure motor monoparesis of the leg and rarely the arm
• Isolated distal leg paresis in smaller cortical infarcts of the precentral gyrus
• Paraparesis with sphincter weakness in bilateral ACA infarcts is rare and associated with circle of Willis anomalies and ACA anatomic variants.

Sensory deficit

Usually has the same distribution as the motor deficit. Leg symptoms are more prominent. The arm and face are often spared. All sensory modalities are usually involved in cortical infarcts.

Unusual sensory patterns:

• Pure sensory deficit resulting from a small cortical infarct in the paracentral lobule (very rare)

Extrapyramidal symptoms

May take the form of involuntary movements, asterixis or hemiparkinsonism.

The pyramidal symptoms may mask the extrapyramidal ones so that the latter become evident several weeks after ictus.

Gait apraxia

Usually manifests as inability to initiate movement and shuffling feet.Astasia may be a rare manifestation of unilateral infarcts involving the anterior corpus callosum.

Incontinence

Appears in ~20% of patients with ACA infarcts.

Neglect

Dominant hemisphere infarcts are associated with contralateral motor neglect.

Non-dominant hemisphere infarcts with contralateral sensory neglect.

Impaired ability to divide attention and perform multiple tasks is sometimes observed.

Callosal disconnection syndrome

Manifests as varying degrees of ideomotor apraxia, agraphia, and tactile anomia that are restricted to the left hand (irrespective of lesion side).

Abulia

Decrease in spontaneous initiation of speech or activity, decreased persistence with tasks and increased response latency.

Extreme abulia takes the form of akinetic mutism which may be difficult to differentiate from the stuporous or “locked-in” state.

Abulia is not uncommon in ACA infarcts. It is more common in bilateral lesions (~67%) followed by left (~51%) and right (~25%) sided lesions.

Mood disorders

Depression is more common in large ACA territory infarcts.

Emotional incontinence (inappropriate laughter or crying) is rare.

Agitation and hyperactivity is associated with unilateral caudate lesions.

Euphoria and a syndrome of emotional lability and poor judgement is associated with infarction of the mesial frontal areas.

Aphasia

Most often takes the form of transcortical motor aphasia.

Grasp reflex

Usually associated with unilateral lesions.

Involuntary movements that may take the form of simple, quasi-reflexive grasping or groping.

A more dramatic form is the alien limb phenomenon where the movements are more complex and may interfere and/or conflict with the other limb. This almost always results from callosal damage often in combination with damage to the supplementary motor area and cingulate cortex.