Increased Evoked Potentials and Behavioral Indices in Response to Pain Among Individuals with Intellectual Disability.
OBJECTIVE
Previous studies on the sensitivity and reactivity to pain of individuals with intellectual disability (ID) are inconsistent. The inconsistency may result from the reliance on self-reports and facial expressions of pain that are subject to internal and external biases. The aim was therefore to evaluate the reactivity to pain of individuals with ID by recording pain-evoked potentials (EPs), here for the first time, and testing their association with behavioral pain indices.


METHODS
Forty-one healthy adults, 16 with mild-moderate ID and 25 controls.


METHODS
Subjects received series of phasic heat stimuli and rated their pain on self-report scales. Changes in facial expressions and in pain EPs were recorded and analyzed offline.


RESULTS
Pain self-reports, facial expressions, and the N2P2 amplitudes of the EPs exhibited stimulus-response relationship with stimulation intensity in both groups. The facial expressions and N2P2 amplitudes of individuals with ID were increased and N2P2 latency prolonged compared with controls. N2P2 amplitudes correlated with self-reports only in controls.


CONCLUSIONS
Individuals with ID are hypersensitive/reactive to pain, a finding bearing clinical implications. Although pain EPs may reflect a somewhat different aspect of pain than the behavioral indices do, there is evidence to support their use to record pain in noncommunicative individuals, pending further validation.
Departments of Anatomy.
Tali
T
Benromano
Departments of Anatomy.|Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel.
Chaim G
CG
Pick
Laboratory of Clinical Neurophysiology, Department of Neurology, Rambam Health Care Campus, Faculty of Medicine, Technion and Institute of Technology, Haifa, Israel.
Yelena
Y
Granovsky
Departments of Anatomy.|Physical Therapy, Sackler Faculty of Medicine.|Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel.
Ruth
R
Defrin
D000328:Adult; D005073:Evoked Potentials, Somatosensory; D005149:Facial Expression; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000175:diagnosis*; D008607:Intellectual Disability; D008297:Male; D010147:Pain Measurement / Q000379:methods*
Cognitive Impairment; Evoked Potentials; Experimental Pain; Facial Expressions; Pain Behavior; Pain Perception