What are the causes of aphasia in an adult patient with a possible history of stroke or traumatic brain injury?

Causes of Aphasia

Aphasia is most commonly caused by stroke, particularly left hemispheric ischemic or hemorrhagic stroke, followed by traumatic brain injury (TBI), with stroke accounting for the vast majority of cases affecting 21-38% of acute stroke patients. 1

Primary Etiologies

Stroke (Most Common Cause)

• Left hemispheric strokes are the predominant cause, as aphasia is "commonly and almost exclusively seen with left hemispheric strokes" 1
• Both ischemic and hemorrhagic strokes can produce aphasia, though recovery patterns differ between the two 2
• Stroke-related aphasia affects approximately 21-38% of acute stroke patients, making it the most common neuropsychological consequence of stroke 1, 2
• The mechanism involves damage to the brain's language network, typically in the left hemisphere 3

Traumatic Brain Injury

• TBI is the second major cause of aphasia in adults, producing similar language impairments to stroke 4
• TBI-related aphasia results from direct brain damage affecting language processing areas 4

Procedure-Related Brain Injury

• Invasive cardiovascular procedures (particularly percutaneous coronary intervention) can cause aphasia through cerebral embolism, thromboembolism, or hypoperfusion 1
• Thromboembolism accounts for approximately 70-80% of procedure-related strokes, while hypoperfusion causes 20-30% 1
• These procedure-related injuries manifest as acute focal neurological deficits including aphasia 1

Pathophysiological Mechanisms

Direct Tissue Damage

• Acute ischemic injury to language areas from arterial occlusion or hypoperfusion 1, 2
• Hemorrhagic destruction of language networks 2
• Embolic events during cardiac procedures causing focal infarction 1

Contributing Factors to Cognitive Decline

• Pre-existing cerebral small-vessel disease may worsen post-stroke aphasia outcomes 1
• Mixed pathology including vascular disease combined with neurodegenerative conditions like Alzheimer's disease can complicate the clinical picture 1
• Covert brain lesions from prior subclinical events may reduce cerebral reserve 1

Clinical Context and Risk Factors

Timing Considerations

• Intraprocedural stroke occurs during interventions, typically diagnosed when patients emerge from anesthesia 1
• Early postprocedural stroke (within 7 days) relates to arrhythmias and hemodynamic factors 1
• Late postprocedural stroke (7 days to 1 month) associates with overall atherothrombotic risk 1

Associated Conditions

• Poststroke depression affects one-third of patients in the first year and can compound cognitive symptoms 1
• Pre-existing cognitive impairment from vascular or neurodegenerative disease may be unmasked or worsened by stroke 1

Critical Diagnostic Pitfalls

• Do not assume aphasia only occurs with large strokes—smaller strategic lesions in language areas can produce significant aphasia 2
• Distinguish aphasia from dysarthria (motor speech disorder) and apraxia of speech, which have intact language formulation but impaired motor execution 5
• Screen for reversible causes of cognitive impairment that may mimic or worsen aphasia, including metabolic derangements, medications, and depression 1
• Recognize that aphasia may be masked in the periprocedural phase by sedation or anesthesia 1