Evaluation of pain in healthy newborns and in newborns with developmental problems (Down syndrome)

Perspectives on pain in Down syndrome

Down syndrome (DS) or trisomy 21 is a genetic condition often accompanied by chronic pain caused by congenital abnormalities and/or conditions, such as osteoarthritis, recurrent infections, and leukemia. Although DS patients are more susceptible to chronic pain as compared to the general population, the pain experience in these individuals may vary, attributed to the heterogenous structural and functional differences in the central nervous system, which might result in abnormal pain sensory information transduction, transmission, modulation, and perception. We tried to elaborate on some key questions and possible explanations in this review. Further clarification of the mechanisms underlying such abnormal conditions induced by the structural and functional differences is needed to help pain management in DS patients.

Pain Management in the Most Vulnerable Intellectual Disability: A Review

This review is made up of two parts; the first part discussing intellectual disability (ID) in general, while the second part covers the pain associated with intellectual disability and the challenges and practical tips for the management of pain associated with (ID). Intellectual disability is characterized by deficits in general mental abilities, such as reasoning, problem solving, planning, abstract thinking, judgment, academic learning, and learning from experience. ID is a disorder with no definite cause but has multiple risk factors, including genetic, medical, and acquired. Vulnerable populations such as individuals with intellectual disability may experience more pain than the general population due to additional comorbidities and secondary conditions, or at least the same frequency of pain as in the general population. Pain in patients with ID remains largely unrecognized and untreated due to barriers to verbal and non-verbal communication. It is important to identify patients at risk to promptly prevent or minimize those risk factors. As pain is multifactorial, thus, a multimodal approach using both pharmacotherapy and non-pharmacological management is often the most beneficial. Parents and caregivers should be oriented to this disorder, given adequate training and education, and be actively involved with the treatment program. Significant work to create new pain assessment tools to improve pain practices for individuals with ID has taken place, including neuroimaging and electrophysiological studies. Recent advances in technology-based interventions such as virtual reality and artificial intelligence are rapidly growing to help give patients with ID promising results to develop pain coping skills with effective reduction of pain and anxiety. Therefore, this narrative review highlights the different aspects regarding the current status of the pain associated with intellectual disability, with more emphasis on the recent pieces of evidence for the assessment and management of pain among populations with intellectual disability.

Unique Pain Responses in Different Etiological Subgroups of Intellectual and Developmental Disabilities

We studied whether there exist variations in pain responses between different intellectual and developmental disability (IDD) etiologies. Self-reports and facial expressions (Facial Action Coding System = FACS) were recorded during experimental pressure stimuli and compared among 31 individuals with IDD-13 with cerebral palsy (CP), nine with Down syndrome (DS), nine with unspecified origin (UIDD)-and among 15 typically developing controls (TDCs). The CP and DS groups had higher pain ratings and FACS scores compared to the UIDD and TDC groups, and steeper stimulus-response functions. The DS group exhibited the most diverse facial expressions. There were variations in the foci of facial expressions between groups. It appears that different IDD etiologies display distinct pain responses.

Pain Behavior of People with Intellectual and Developmental Disabilities Coded with the New PAIC-15 and Validation of Its Arabic Translation

Pain management necessitates assessment of pain; the gold standard being self-report. Among individuals with intellectual and developmental disabilities (IDD), self-report may be limited and therefore indirect methods for pain assessment are required. A new, internationally agreed upon and user-friendly observational tool was recently published—the Pain Assessment in Impaired Cognition (PAIC-15). The current study’s aims were: to test the use of the PAIC-15 in assessing pain among people with IDD and to translate the PAIC-15 into Arabic for dissemination among Arabic-speaking professionals. Pain behavior following experimental pressure stimuli was analyzed among 30 individuals with IDD and 15 typically developing controls (TDCs). Translation of the PAIC followed the forward–backward approach; and reliability between the two versions and between raters was calculated. Observational scores with the PAIC-15 exhibited a stimulus–response relationship with pressure stimulation. Those of the IDD group were greater than those of the TDC group. The overall agreement between the English and Arabic versions was high (ICC = 0.89); single items exhibited moderate to high agreement levels. Inter-rater reliability was high (ICC = 0.92). Both versions of the PAIC-15 are feasible and reliable tools to record pain behavior in individuals with IDD. Future studies using these tools in clinical settings are warranted.

Dosing of Opioid Medications During and After Pediatric Cardiac Surgery for Children With Down Syndrome

OBJECTIVE

To determine whether children with Down syndrome (DS) receive higher doses of opioid medications compared with children without DS for repair of complete atrioventricular canal (CAVC).

DESIGN

A retrospective chart review of children with and without DS who underwent primary repair of CAVC. The exclusion criteria included unbalanced CAVC and patients undergoing biventricular staging procedures. The primary outcome was oral morphine equivalents (OME) received in the first 24 hours after surgery. The secondary outcomes included intraoperative OME, OME at 48 and 72 hours, nonopioid analgesic and sedative medications received, pain scores, time to extubation, and length of stay.

SETTING

A pediatric academic medical center in the United States.

PARTICIPANTS

One hundred thirty-one patients with DS and 24 without, all <two years old, who underwent a CAVC repair.

INTERVENTIONS

Not applicable.

MEASUREMENTS AND MAIN RESULTS

Patients with DS were older than patients without DS (median 96.3 days [interquartile range {IQR} 70.7-128.2] v 75.9 days [IQR 49.8-107.3], p = 0.033) but otherwise not statistically different in the baseline characteristics. There was no difference in OME received in the first 24 hours postoperatively between groups (3.01 mg/kg [IQR 1.23-5.43] v 3.57 mg/kg [IQR 1.54-7.06], p = 0.202). OME at 48 and 72 hours was lower in the DS group compared with the control group. Similar amounts of opioid and non-opioid analgesics and sedatives were otherwise given to both groups of patients. Median pain scores did not differ between groups.

CONCLUSIONS

These results suggested that patients with DS undergoing CAVC repair do not have increased opioid requirements compared with a similar control group.

Specific Behavioral Responses Rather Than Autonomic Responses Can Indicate and Quantify Acute Pain among Individuals with Intellectual and Developmental Disabilities

Individuals with intellectual and developmental disabilities (IDD) are at a high risk of experiencing pain. Pain management requires assessment, a challenging mission considering the impaired communication skills in IDD. We analyzed subjective and objective responses following calibrated experimental stimuli to determine whether they can differentiate between painful and non-painful states, and adequately quantify pain among individuals with IDD. Eighteen adults with IDD and 21 healthy controls (HC) received experimental pressure stimuli (innocuous, mildly noxious, and moderately noxious). Facial expressions (analyzed with the Facial Action Coding System (FACS)) and autonomic function (heart rate, heart rate variability (HRV), pulse, and galvanic skin response (GSR)) were continuously monitored, and self-reports using a pyramid and a numeric scale were obtained. Significant stimulus-response relationships were observed for the FACS and pyramid scores (but not for the numeric scores), and specific action units could differentiate between the noxious levels among the IDD group. FACS scores of the IDD group were higher and steeper than those of HC. HRV was overall lower among the IDD group, and GSR increased during noxious stimulation in both groups. In conclusion, the facial expressions and self-reports seem to reliably detect and quantify pain among individuals with mild-moderate IDD; their enhanced responses may indicate increased pain sensitivity that requires careful clinical consideration.

Temporal assessment of neonatal pain after airway aspiration

OBJECTIVE

To temporally assess a painful stimulus in premature infants using 3 neonatal pain scales.

METHODS

A total of 83 premature infants were observed during airway aspiration by 3 evaluators (E1, E2 and E3) using 3 pain assessment scales (Neonatal Facial Coding System - NFCS; Neonatal Infant Pain Scale - NIPS; and Premature Infant Pain Profile - PIPP) at 5 time points: T1 (before airway aspiration), T2 (during airway aspiration), T3 (1 minute after airway aspiration), T4 (3 minutes after airway aspiration), and T5 (5 minutes after airway aspiration). Light's Kappa (agreement among examiners and among scales at each time point) and the McNemar test (comparison among time points) were used considering p < 0.05.

RESULTS

There was a significant difference between the 3 examiners for T1 and T2 using the 3 scales. In T3, pain was observed in 22.9%/E1, 28.9%/E2, and 24.1%/E3 according to the NFCS; 22.9%/E1, 21.7%/E2, and 16.9%/E3 according to the NIPS; and 49.4%/E1, 53.9%/E2, and 47%/E3 according to the PIPP. There was a difference between T1 and T3 using the 3 scales, except for 2 examiners for the PIPP (E2: p = 0.15/E3: p = 0.17). Comparing T4 and T5 to T1, there was no difference in the 3 scales.

CONCLUSION

Premature infants required at least 3 minutes to return to their initial state of rest (no pain).

Self-Reported Presence and Experience of Pain in Adults with Down Syndrome

Objective

The aim was to examine whether the presence of pain (based on physical conditions and participants' report) and self-reported pain experience in adults with Down syndrome (DS) differ from general population controls.

Design

Cross-sectional study of 224 adults with DS (mean age = 38.1 years, mild-severe intellectual disabilities) and 142 age-matched controls (median age = 40.5 years, mean estimated IQ = 105.7) in the Netherlands.

Methods

File-based medical information was evaluated. Self-reported presence and experience of pain were assessed in rest and after movement during a test session (affect with facial affective scale (FAS: 0.04-0.97), intensity assessed with numeric rating scale (NRS: 0-10).

Results

Compared with controls, more DS participants had physical conditions that may cause pain and/or discomfort ( p  = .004, 50% vs 35%), but fewer DS participants reported pain during the test session ( p  = .003, 58% vs 73%). Of the participants who indicated pain and comprehended self-reporting scales ( n  = 198 FAS, n  = 161 NRS), the DS group reported a higher pain affect and intensity than the controls ( p  < .001, FAS: 0.75-0.85 vs 0.50-0.59, NRS: 6.00-7.94 vs 2.00-3.73).

Conclusions

Not all adults with DS and painful/discomforting physical conditions reported pain. Those who did indicated a higher pain experience than adults from the general population. Research into spontaneous self-report of pain, repeated pain assessment, and acute pain is needed in people with DS for more insight into pain experience and mismatches between self-report and medical information.

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.

Quantitative sensory testing of temperature, pain, and touch in adults with Down syndrome

The spinothalamic pathway mediates sensations of temperature, pain, and touch. These functions seem impaired in children with Down syndrome (DS), but have not been extensively examined in adults. The objective of the present study was to compare the spinothalamic-mediated sensory functions between adults with DS and adults from the general population and to examine in the DS group the relationship between the sensory functions and level of intellectual functioning. Quantitative sensory testing (QST) was performed in 188 adults with DS (mean age 37.5 years) and 142 age-matched control participants (median age 40.5 years). Temperature, pain, and touch were evaluated with tests for cold-warm discrimination, sharp-dull discrimination (pinprick), and tactile threshold, respectively. Level of intellectual functioning was estimated with the Social Functioning Scale for Intellectual Disability (intellectual disability level) and the Wechsler Preschool and Primary Scale of Intelligence--Revised (intelligence level). Overall, the difference in spinothalamic-mediated sensory functions between the DS and control groups was not statistically significant. However, DS participants with a lower intelligence level had a statistically significant lower performance on the sharp-dull discrimination test than DS participants with higher intelligence level (adjusted p=.006) and control participants (adjusted p=.017). It was concluded that intellectual functioning level is an important factor to take into account for the assessment of spinothalamic-mediated sensory functioning in adults with DS: a lower level could coincide with impaired sensory functioning, but could also hamper QST assessment.

Pain perception in people with Down syndrome: a synthesis of clinical and experimental research

People with an intellectual disability experience both acute and chronic pain with at least the same frequency as the general population. However, considerably less is known about the pain perception of people with Down syndrome. In this review paper, we evaluated the available clinical and experimental evidence. Some experimental studies of acute pain have indicated that pain threshold was higher than normal but only when using a reaction time method to measure pain sensitivity. However, when reaction time is not part of the calculation of the pain threshold, pain sensitivity in people with Down syndrome is in fact lower than normal (more sensitive to pain). Clinical studies of chronic pain have shown that people with an intellectual disability experience chronic pain and within that population, people with Down syndrome also experience chronic pain, but the precise prevalence of chronic pain in Down syndrome has yet to be established. Taken together, the literature suggests that people with Down syndrome experience pain, both acute and chronic, with at least the same frequency as the rest of the population. Furthermore, the evidence suggests that although acute pain expression appears to be delayed, once pain is registered, there appears to be a magnified pain response. We conclude by proposing an agenda for future research in this area.