What type of aphasia is most commonly caused by a stroke?

Types of Aphasia Caused by Stroke

Aphasia affects approximately one-third of stroke survivors, with Broca's, Wernicke's, global, and anomic aphasia being the most common types caused by stroke.

Classification of Post-Stroke Aphasias

Aphasia is an acquired language impairment following brain damage that affects language modalities including expression, comprehension, reading, and writing. For practical clinical use, aphasias are typically classified according to fluency, comprehension, and naming abilities 1:

Nonfluent Aphasias

• Broca's aphasia: Characterized by difficulty with word-finding and speech production, telegraphic speech patterns with hesitations, and relatively preserved comprehension
• Transcortical motor aphasia: Impaired speech initiation with preserved repetition
• Global aphasia: Severe impairment of all language functions
• Mixed transcortical aphasia: Severely impaired comprehension and production with preserved repetition

Fluent Aphasias

• Wernicke's aphasia: Characterized by fluent but meaningless speech with poor comprehension
• Conduction aphasia: Fluent speech with good comprehension but poor repetition
• Anomic aphasia: Word-finding difficulties with preserved comprehension and fluent speech
• Transcortical sensory aphasia: Impaired comprehension with preserved repetition
• Subcortical aphasia: Variable presentation depending on specific subcortical structures involved

Neuroanatomical Correlates

The type of aphasia is closely related to the location of the stroke lesion 2:

• Broca's aphasia: Associated with lesions in the left inferior frontal cortex
• Wernicke's aphasia: Associated with posterior temporal-parietal lesions
• Conduction aphasia: Associated with damage to the dorsal superior longitudinal and arcuate fasciculus
• Comprehension deficits: Associated with ventral extreme capsule fiber damage

Functional connectivity studies show that increased resting state connectivity between left and right superior temporal gyri correlates with poorer language function in acute lacunar stroke patients 2.

Prevalence and Recovery

Aphasia occurs in approximately 30-38% of acute stroke patients 1, 3. Recovery patterns vary by aphasia type:

• Recovery from aphasia caused by ischemic stroke is most intensive in the first two weeks
• Recovery from aphasia caused by hemorrhagic stroke is slower, occurring from the fourth to eighth week post-stroke 1
• Spontaneous recovery is most remarkable in the first three months after stroke onset 1

Assessment and Management

Assessment

All stroke patients should be screened for communication disorders, including aphasia, by a certified speech-language pathologist 4. A comprehensive assessment should evaluate:

• Comprehension
• Speaking
• Reading
• Writing
• Gesturing
• Use of technology
• Pragmatics
• Conversation

Treatment Approaches

1. Speech and Language Therapy (SLT):

   • SLT results in clinically and statistically significant benefits to patients' functional communication, reading, writing, and expressive language 3
   • The American Heart Association recommends early access to intensive speech and language therapy 4
   • Therapy should be provided for at least 45 minutes daily, five days a week 4
   • For chronic aphasia (>6 months post-stroke), implement intensive therapy of at least 10 hours/week for 3 weeks, plus 5+ hours/week of self-managed training 4

2. Intensity and Duration:

   • Evidence suggests that higher intensity, higher dose, or longer duration therapy may be more beneficial for functional communication 3
   • However, high-intensity interventions have higher dropout rates and may not be acceptable to all patients 3

3. Alternative Communication Strategies:

   • Implement alternative communication strategies including gesture training, drawing techniques, writing strategies, and augmentative and alternative communication (AAC) devices 4

4. Supplemental Interventions:

   • Computer-based therapy can supplement therapist-provided intervention 4
   • Group therapy can improve specific linguistic processes with comparable outcomes to individual therapy 4
   • Communication partner training for family members and caregivers 4

5. Pharmacological Approaches:

   • Promising medications such as donepezil, memantine, and galantamine may provide benefit when used with speech-language therapy 4, 5, 6
   • Piracetam may be effective in recovery from aphasia when started soon after stroke, but its efficacy diminishes in chronic aphasia 6
   • Drugs acting on catecholamine systems (bromocriptine, dexamfetamine) have shown varying degrees of efficacy 6

Conclusion

Understanding the type of aphasia is crucial for predicting recovery and planning appropriate interventions. While speech-language therapy remains the mainstay of treatment, the integration of intensive therapy approaches, alternative communication strategies, and potentially pharmacological agents may optimize recovery outcomes for stroke survivors with aphasia.