Understanding Right-Hemisphere Language Disorders Through a Half-Century of Research: A Systematic Review

Area of Science:

• Neurolinguistics
• Cognitive Neuroscience
• Clinical Psychology

Background:

• Right-hemisphere (RH) stroke is associated with diverse language deficits.
• These deficits extend beyond grammar to semantics and pragmatics, termed apragmatism.
• Existing research requires synthesis within the apragmatism framework.

Purpose of the Study:

• To systematically review and summarize research on language deficits after RH stroke.
• To consolidate findings within the framework of apragmatism.
• To identify linguistic and extralinguistic components affected by RH stroke.

Main Methods:

• A systematic review guided by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards.
• Analysis of 55 years of research, including 233 articles and data from over 4,300 participants with RH stroke.
• Extraction and categorization of linguistic and extralinguistic apragmatism components.

Main Results:

• Linguistic deficits observed at word, sentence, and discourse levels, particularly in figurative language, inferencing, context use, and humor.
• Production deficits were more pronounced in less-structured tasks, affecting discourse coherence, cohesion, intended meaning, and emotional processing.
• Extralinguistic deficits primarily involved comprehension and production of facial expressions, with limited examination of other nonverbal cues.

Conclusions:

• RH stroke can lead to significant language deficits across multiple domains, including linguistic and extralinguistic apragmatism.
• Key affected areas include figurative language, inferencing, emotion processing, and understanding intended meaning.
• Methodological limitations in current research, such as poor participant descriptions and assessment methods, impede a comprehensive understanding of these challenges.