Can a stroke cause ipsilateral facial and arm weakness?

Stroke and Ipsilateral Facial and Arm Weakness

No, a typical stroke does not cause ipsilateral facial and arm weakness. Stroke classically causes contralateral weakness due to the crossing of motor pathways in the brainstem.

Stroke Symptoms and Neuroanatomy

• Strokes typically cause contralateral (opposite side) weakness due to the decussation (crossing) of the corticospinal tract in the medulla oblongata 1
• The classic presentation of stroke includes contralateral hemiparesis affecting the face, arm, and/or leg 1
• Symptoms of stroke in the distribution of the right internal carotid artery or middle cerebral artery include left-sided weakness, left-sided sensory loss, and other left-sided deficits 1
• Similarly, left hemisphere strokes typically cause right-sided weakness and sensory deficits 1

Rare Cases of Ipsilateral Weakness

• Ipsilateral weakness following stroke is extremely rare, occurring in only about 0.17% of ischemic stroke patients 2

• When ipsilateral weakness does occur, it's typically associated with:

  • Previous contralateral stroke history 2
  • Functional reorganization of corticospinal tract pathways within the ipsilateral hemisphere 3
  • Recruitment of uncrossed components of the corticospinal tract in response to previous injury 3, 2

• In a case series of six patients with ipsilateral weakness following stroke, the lesions involved the corona radiata, internal capsule, basal ganglia, insula, and thalamus 3

Mechanisms of Ipsilateral Motor Control

• Some degree of bilateral motor control can be exerted by all cerebral hemisphere areas involved in sensory-motor functions, but ipsilateral influence is never greater than contralateral influence 4
• The proportion of ipsilateral to contralateral control appears related to the degree of continuous sensory feedback required by particular tasks 4
• Functional neuroimaging studies in patients with ipsilateral hemiparesis have shown activation of both cerebral hemispheres, suggesting compensatory mechanisms 2

Recovery Patterns

• When ipsilateral weakness does occur after stroke, proximal and distal arm weakness typically shows maximum recovery within one month following onset 5
• However, this weakness may not completely resolve, indicating it's not merely a temporary phenomenon 5
• Motor function of proximal and distal arm segments may be mediated by different neuronal circuits, affecting recovery patterns 5

Clinical Implications

• When evaluating patients with suspected stroke, clinicians should recognize that:
  • Unilateral weakness (face, arm, and/or leg) is a high-risk symptom requiring immediate assessment 1
  • The presence of ipsilateral rather than contralateral weakness should prompt consideration of alternative diagnoses or unusual stroke mechanisms 3, 2
  • Patients with ipsilateral weakness after stroke often have a history of previous stroke on the contralateral side 2

In conclusion, while stroke typically causes contralateral weakness due to the crossing of motor pathways, rare cases of ipsilateral weakness can occur through alternative neurological mechanisms, usually in patients with previous stroke history and neuroplastic changes.