Sensory Modulation Disorder (SMD) and Pain: A New Perspective

Area of Science:

• Neuroscience
• Clinical Psychology
• Occupational Therapy

Background:

• Sensory modulation disorder (SMD) impacts sensory processing, with sensory over-responsivity (SOR) causing stimuli to be perceived as painful.
• SOR co-occurs with pain hypersensitivity, affecting daily activities and quality of life.
• Previous research shows abnormal pain perception in individuals with SMD.

Purpose of the Study:

• To review current knowledge on the relationship between SMD and pain.
• To propose a neurophysiological mechanism-based model for the interrelation between SMD and pain.
• To highlight pain as a crucial, yet under-recognized, aspect of SMD.

Main Methods:

• Literature review of empirical studies on SMD and pain.
• Analysis of quantitative sensory testing (QST) data.
• Synthesis of findings on central nervous system (CNS) processing of sensory stimuli.

Main Results:

• Individuals with SOR exhibit abnormal pain processing, including hyperalgesia and prolonged pain sensations.
• Altered pain processing in SOR is linked to CNS mechanisms, specifically enhanced pain pathway facilitation and impaired pain inhibition.
• SOR is identified as a risk factor and comorbidity for chronic non-neuropathic pain disorders.

Conclusions:

• Shared neurophysiological mechanisms, including cortical hyper-excitation and excitatory-inhibitory imbalance, likely underlie both SMD and pain hypersensitivity.
• Integrating the pain domain into SMD research is essential for understanding its pathogenesis and developing mechanism-based therapies.
• This review establishes a foundation for future research and therapeutic interventions targeting the interplay between sensory modulation and pain.