Unilateral Spatial Neglect without Hemiplegia: The Output-Mode Effect Revisited

Area of Science:

• Neuroscience
• Cognitive Psychology
• Rehabilitation Medicine

Background:

• Unilateral spatial neglect (USN) is uncommon in non-hemiplegic right-hemisphere stroke patients.
• Previous research indicates a left-hand advantage in neglect testing for these patients.
• The underlying mechanisms of this "output-mode effect" are not fully understood.

Purpose of the Study:

• To investigate the temporal dynamics of the output-mode effect in non-hemiplegic stroke patients with left-USN.
• To explore how hand laterality influences neglect symptom expression over time.

Main Methods:

• Utilized a line-bisection task to assess left-USN.
• Analyzed performance in 9 non-hemiplegic stroke patients with left-USN.
• Examined the influence of hand laterality (left vs. right) on task performance.

Main Results:

• Early testing (≤ 6 weeks post-stroke) showed variable hand laterality effects.
• A clear left-hand advantage emerged in most patients after 6 weeks post-stroke.
• These findings contrast with earlier studies relying on late-stage testing.

Conclusions:

• The expression of the output-mode effect in USN demonstrates dynamic changes in the early weeks post-stroke.
• These dynamics may reflect evolving inter-hemispheric balance during recovery.
• Therapeutic strategies targeting inter-hemispheric balance should consider these temporal variations.