Aphasia Induced by Infratentorial Ischemic Stroke: Two Case Reports

Area of Science:

• Neurology
• Neuroscience
• Stroke Research

Background:

• Aphasia typically results from cerebral hemisphere lesions.
• Infratentorial strokes, particularly in the cerebellum and midbrain, are rarely associated with aphasia.
• The underlying mechanisms of infratentorial stroke-induced aphasia remain poorly understood.

Observation:

• Two patients with acute ischemic infratentorial strokes (right cerebellar hemisphere and right midbrain) presented with distinct types of aphasia.
• Patient 1 developed Wernicke's aphasia and ataxia.
• Patient 2 experienced transcortical sensory aphasia and one-and-a-half syndrome.

Findings:

• Single-photon emission computed tomography (SPECT) revealed hypoperfusion in the left cerebral hemisphere in both patients.
• These cerebral lesions were remote from the acute infratentorial infarcts.
• The observed pattern suggests a diaschisis phenomenon impacting language networks.

Implications:

• The findings propose "crossed cerebello-cerebral diaschisis" as a potential mechanism for aphasia after infratentorial stroke.
• This challenges traditional models of aphasia localization.
• Further research is needed to elucidate the neuroanatomical pathways involved in this phenomenon.