Complex regional pain syndrome (CRPS) was once thought to affect only adults, but over the past 30 years, doctors have been diagnosing CRPS more often in patients under 18 years of age. Originally called reflex sympathetic dystrophy, or RSD, the descriptions of the syndrome were defined and the name changed to reflect two types of the syndrome: CRPS type 1 and CRPS type 2.
Despite the change in name and description, doctors still don’t know what the pathophysiology or causes are. They do know that the quality and type of pain varies from person to person, and can change in one person over time. The authors of this study looked at pain reports and patterns in children and adolescents with CRPS using not only standard neurological or nerve testing, but also – for the first time with children – quantitative sensory testing, or QST, was used. QST is a computer testing system that assesses damage to the nerve endings, testing their reactions to vibrations and changes in temperature. These findings are then compared with the same tests performed on the patient’s non-affected side.
The researchers recruited 63 patients between the ages of 7 and 17 years who had been diagnosed with CRPS. After applying the inclusion criteria and performing preliminary tests, 42 patients (40 girls) remained in the final study group. The patients were, on average, 13.2 years old. All patients had developed CRPS following a specific injury: 13 from sports-related injury, 10 from an accidental sprain or strain, 3 fractures, 3 after surgery, 3 after a soft tissue injury, and 1 after experiencing a deep vein thrombosis, or a clot in a vein. The average length of time that pain has been present was 12.6 months, ranging from 0.5 to 72 months. Besides the pain, other reported symptoms were: color changes to the skin (red or purple) in 28 patients, excessive sweating in the area in 12, dry skin in 15, swelling in 25, a change in hair in the region (less or more) in 28, and a change in nail growth in 7. A warmer skin temperature at the affected area was reported in 20 patients and cooler temperature in 5.
When the patients were examined, 23 patients showed signs of mild-to-moderate muscle wasting and weakness in the affected area, 8 showed mild wasting, and 1 patient had a tremor. Thirty patients were unable or unwilling to bear weight on the affected foot or leg because of the pain.
The researchers reported that, in this study, the onset of CRPS in early teens and the suddenness of the onset were the most common factors, a fact that was in line with previous study findings. Findings are different from that of adults with CRPS because in children and teens, females are overwhelmingly in the majority of CRPS patients with a ratio of 5-13.1 to 1. As well, adults tend to have more tremors than the children.
The results of the QST showed that the intense reaction to cold was higher than to heat, but still low when compared with adults (33.3 percent versus 74-100 percent). Pain reaction to heat was 16.7 percent in children and between 14 percent and 55 percent in adults. Reaction to vibrations in the study group did not differ much from the control group.
The researchers point out that their study did have some limitation, among them the testing was done at the site where pain was most severe. However, the researchers say that their study shows QST can be used in most children with CRPS to find out what alterations in the nerves they are experiencing.