Effect of prism adaptation on neglect hemianesthesia

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Cognitive Psychology

Background:

• Unilateral spatial neglect (USN) is a cognitive deficit often impacting high-level functions.
• Prism adaptation (PA) is a treatment known to improve cognitive aspects of USN.
• Emerging evidence suggests PA may also benefit somatosensory functions in USN.

Purpose of the Study:

• To investigate the specific effects of PA on neglect hemianesthesia, where neglect mimics sensory loss.
• To assess PA's influence on upper limb somatosensory perception in USN patients.

Main Methods:

• A cross-over study involving 21 USN patients undergoing two PA sessions: one with neutral glasses and one with prism glasses.
• Somatosensory function was evaluated using clinical sensibility tests and an electro-cutaneous stimulator to determine perceptual and motor thresholds.
• USN severity was assessed using standard neuropsychological tests including Star cancellation and Line bisection.

Main Results:

• Significant improvements were observed in double extinction and electro-cutaneous perceptual thresholds for the contralesional hand after prism exposure compared to sham conditions.
• No significant changes were noted for the ipsilesional hand, motor thresholds, or with neutral glasses.
• Personal neglect showed significant amelioration, and results were confirmed in a subgroup replication.

Conclusions:

• Prism adaptation demonstrates a specific effect on neglect hemianesthesia, improving somatosensory perception in the contralesional upper limb.
• The findings suggest PA can ameliorate both sensory and personal neglect symptoms.
• PA may offer a targeted therapeutic approach for somatosensory deficits associated with USN.