Neurologic Findings in Lateral Pontine (AICA) Infarction

Anatomical Localization

Expected Cranial‑Nerve Involvement

Differential Exclusions Based on Neuroanatomy

Classic AICA Syndrome Features

Stroke Localization in the Brainstem

Anatomical Reasoning for Localization

• Ipsilateral facial involvement indicates disruption of the trigeminal sensory pathways, which are located in the brainstem, according to the American College of Radiology 3

Distinguishing Features of Brainstem Lesions

• An internal capsule stroke would produce contralateral deficits affecting both face and body on the same side, as noted by clinical guidelines 4
• Cortical lesions produce contralateral deficits only, as stated by the American College of Radiology and other clinical guidelines 4

Diagnostic Approach

• Urgent neuroimaging with MRI (diffusion-weighted imaging) is essential to confirm the diagnosis and guide acute management, as recommended by the American Heart Association, published in Circulation and Stroke 5, 6

Brainstem Infarction Diagnosis and Presentation

Diagnostic Criteria and Presentation

• The American Heart Association recommends urgent MRI with diffusion-weighted imaging (DWI) for detecting acute pontine infarcts, which can be as small as 4mm and easily missed, with a diagnostic accuracy supported by level of evidence B 7

Differential Diagnosis

• The presence of contralateral body symptoms immediately distinguishes brainstem stroke from Bell's palsy, with a strength of evidence classified as high according to the American Academy of Neurology 7