Physiological and Behavioral Responses to Calibrated Noxious Stimuli Among Individuals with Cerebral Palsy and Intellectual Disability

Objective

As individuals with intellectual disability (ID) due to cerebral palsy (CP) are at high risk of experiencing pain, measuring their pain is crucial for adequate treatment. While verbal reports are the gold standard in pain measurements, they may not be sufficient in ID. The aim was to detect behavioral/autonomic responses that may indicate the presence and intensity of pain in individuals with CP and ID, using calibrated stimuli, here for the first time.

Subjects

Thirteen adults with CP and ID (CPID), 15 healthy controls (HC), and 5 adults with CP with no ID (CPNID).

Methods

Subjects received pressure stimuli of various intensities. Self-reports (using a pyramid scale), facial expressions (retrospectively analyzed with Facial Action Coding System = FACS), and autonomic function (heart rate, heart rate variability, pulse, galvanic skin response) were analyzed.

Results

Self-reports and facial expressions but not the autonomic function exhibited stimulus-response relationship to pressure stimulation among all groups. The CPID group had increased pain ratings and facial expressions compared with controls. In addition, the increase in facial expressions along the increase in noxious stimulation was larger than in controls. Freezing in response to pain was frequent in CPID.

Conclusions

1) Individuals with CP and ID have increased responses to pain; 2) facial expressions and self-reports, but not autonomic variables can reliably indicate their pain intensity; 3) the pyramid scale is suitable for self-report in this population. Although facial expressions may replace verbal reports, increased facial expressions at rest among these individuals may mask pain, especially at lower intensities.

Medical Judgments Across the Range of Reported Pain Severity: Clinician and Lay Perspectives

BACKGROUND

While increasing evidence suggests that observers discount high-severity chronic pain, factors that occasion such discounting are poorly understood, particularly regarding health provider vs lay perspectives.

OBJECTIVE

This study examined the effects of supporting medical evidence and comorbid psychological distress (pain behavior) on medical student and lay clinical judgments of increasingly severe patient pain reports.

DESIGN

In a 2 × 2 × 2 × (7) mixed between- and within-subject design, participants (medical students vs lay) made clinical judgments after reading vignettes describing a hypothetical patient that varied in levels of medical evidence and pain behavior (low vs high) and pain severity (4/10-10/10).

SUBJECTS

Fourth-year medical students (N = 115) and lay persons in the community (N = 300) participated in this research.

RESULTS

While both medical student and lay judgments plateaued at high levels of pain severity, judgments regarding cause (medical vs psychological), treatment (opioid prescription), and disability showed growing divergence as levels of reported pain severity increased. Divergence relative to medical and psychological causes of pain was found irrespective of the level of supporting medical evidence; divergence relative to opioid treatment and support for a disability claim was found when supporting medical evidence was low.

CONCLUSIONS

The results indicate differing expectations of chronic pain treatment for health care providers relative to the lay public that could impact clinical care, especially at high pain severity levels, where lay expectations diverge significantly from those of health professionals.

ATP-sensitive Potassium Channels and L-type Calcium Channels are Involved in Morphine-induced Hyperalgesia after Nociceptive Sensitization in Mice

INTRODUCTION

We investigated the role of ATP-sensitive potassium channels and L-type calcium channels in morphine-induced hyperalgesia after nociceptive sensitization.

METHODS

We used a hotplate apparatus to assess pain behavior in male NMRI mice. Nociceptive sensitization was induced by three days injection of morphine and five days of drug free. On day 9 of the schedule, pain behavior test was performed for evaluating the effects of morphine by itself and along with nimodipine, a blocker of L-type calcium channels and diazoxide, an opener of ATP-sensitive potassium channels. All drugs were injected through an intraperitoneal route.

RESULTS

The results showed that morphine (7.5, 10 and 15 mg/kg) induced analgesia in normal mice, which was prevented by naloxone (1 mg/kg). After nociceptive sensitization, analgesic effect of morphine (10 and 15 mg/kg) was significantly decreased in sensitized mice. The results showed that nimodipine (2.5, 5, 10 and 20 mg/kg) had no significant effect on pain behavior test in either normal or sensitized mice. However, nimodipine (20 mg/ kg) along with morphine (10 and 15 mg/kg) caused more decrease in morphine analgesia in sensitized mice. Furthermore, diazoxide by itself (0.25, 1, 5 and 20 mg/kg) had also no significant effect on pain behavior in both normal and sensitized mice, but at dose of 20 mg/kg along with morphine (10 and 15 mg/kg) decreased analgesic effect of morphine in sensitized mice.

DISCUSSION

It can be concluded that potassium and calcium channels have some roles in decrease of analgesic effect of morphine after nociceptive sensitization induced by pretreatment of morphine.