Differential Diagnosis for Right Leg Weakness due to Stroke
Single Most Likely Diagnosis
- Left Middle Cerebral Artery (MCA) Stroke: The most common cause of right leg weakness due to stroke is an ischemic or hemorrhagic stroke affecting the left MCA, which supplies the motor cortex controlling the right side of the body, including the leg.
Other Likely Diagnoses
- Left Anterior Cerebral Artery (ACA) Stroke: The ACA supplies the medial aspect of the brain, including the motor cortex for the lower limb. A stroke in this area can cause weakness or paralysis of the right leg.
- Left Internal Capsule Stroke: The internal capsule is a structure that contains ascending and descending tracts, including those responsible for motor function. A stroke here can cause contralateral weakness, including right leg weakness.
- Left Corona Radiata Stroke: The corona radiata is a region of white matter in the brain where motor tracts from the cortex converge. A stroke affecting this area can lead to weakness of the right leg.
Do Not Miss Diagnoses
- Brainstem Stroke: Although less common, a stroke in the brainstem can cause crossed deficits (e.g., right leg weakness and left arm weakness) or bilateral weakness. Missing this diagnosis could lead to delayed treatment of a potentially life-threatening condition.
- Cerebellar Stroke: A cerebellar stroke can cause ataxia, which might be mistaken for weakness. However, cerebellar strokes can also lead to increased intracranial pressure due to edema, making prompt diagnosis crucial.
Rare Diagnoses
- Subcortical Stroke (e.g., in the basal ganglia or thalamus): While less common, strokes in subcortical structures can cause a variety of motor deficits, including contralateral weakness.
- Moyamoya Disease: A rare condition causing stenosis or occlusion of the internal carotid artery and its branches, leading to stroke. It can present with unilateral leg weakness among other symptoms.
- Vascular Malformations (e.g., Arteriovenous Malformations): These are abnormal connections between arteries and veins that can cause stroke due to bleeding or ischemia, potentially leading to focal neurological deficits like right leg weakness.