AT RHEUMATOLOGY 2016

GLASGOW (FRONTLINE MEDICAL NEWS) Two novel clinical signs can be used to determine whether people who have had a fracture are likely to develop complex regional pain syndrome, a condition for which there is currently no specific diagnostic test.

The way in which patients perceived which of their fingers was being touched when their eyes were closed (finger perception) and the position of different parts of their body in relation to one another generally (body scheme) were found to be reliable ways of identifying those who would experience prolonged pain in the future. The positive and negative predictive values of using those tests together were a respective 84.1% and 76.9%.

“Digit misperception and body scheme combined can be useful in predicting chronic pain,” Dr. Nicholas Shenker of Addenbrooke’s Hospital in Cambridge, England, said in an interview at the British Society for Rheumatology annual conference.

“This may allow a reduction in chronic pain by identifying a cohort requiring more intensive intervention with physiotherapy and intervention,” he added. It also may help to reduce the incidence of complex regional pain syndrome (CRPS) after sustaining a fracture.

CPRS is characterized by prolonged, intractable pain that often follows injury to a limb, such as a fracture or another traumatic event. “It’s a nervy type pain, burning, and shooting, and it’s a horrible condition,” Dr. Shenker explained. “If you ask patients to rate the amount of pain they get from their condition, whether it is rheumatoid arthritis, fibromyalgia, or osteoarthritis, this is the condition that commonly comes top.”

With differential diagnoses spanning many rheumatologic and neurologic conditions, it is perhaps no surprise that patients with CRPS often go undiagnosed for many months. In fact, according to CRPS Registry UK findings, it can take up to 6 months after symptoms start before patients are diagnosed with the pain syndrome ( Br J Pain. 2015;9[2]:122-8 ).

While pain symptoms may resolve by themselves in about one-third of patients by 3 months and three-quarters of patients by 12 months, there are a significant number of patients whose symptoms do not resolve, and their window of opportunity for treatment may have closed. Although treatment may be largely reassurance based for many, some patients may benefit from early physical therapy or pain medication.

“Once you have any chronic pain condition for more than 12 months, the chances of it getting better are pretty slim. So we want to identify these people early, but that is not easy,” Dr. Shenker observed.

Since there is currently no diagnostic test, Dr. Shenker and his associates identified four novel clinical signs – abnormal finger perception, hand laterality identification, body scheme report, and astereognosis – from a cohort of patients with CRPS and developed tests for them.

Finger perception was assessed by asking the subjects to place their hands on their laps, close their eyes and say which finger or thumb was being touched within a 20-second time limit. A positive test was a score of 8 or less out of 10.

Hand laterality was tested using a computer program showing the subjects a series of images of left and right hands and asking them to click whether the image was of a person’s right or left hand. A positive test was a score of fewer than 50 out of 56 or if the subject took longer than 3 minutes to complete the exercise.

Astereognosis, the inability to identify an object by the touch of the hands only, was assessed by asking the subjects to close their eyes and present their hand palms upward, then placing three different objects into it and asking them what they were touching. A test was considered positive if only two out of three objects were recognized, or if the subjects took longer than 6 seconds to identify the objects.

Finally, body scheme is about assessing how patients generally sense the parts of their bodies with their eyes closed, or how one side of the body compares in terms of size, weight, and length to the other. For this test, the body is divided into 17 areas, and over the course of 2 minutes, patients are asked to describe, without moving, how their left side compares to their right side. A test is considered positive if patients’ responses differ by more than 10% in two contiguous areas, such as the arm and elbow.

Only finger perception and body scheme were found to have good positive and negative predictive values individually.

The aim of the prospective observational cohort study Dr. Shenkar presented at the meeting on behalf of colleague Dr. Anoop Kuttikat was to look at those signs to see how common those scenarios were and to determine if these could be used as simple bedside tests to identify those likely to develop CRPS.

Dr. Shenkar reported data on 47 patients aged a mean of 53 years who needed a plaster cast for an upper (wrist) or lower (ankle/tibia) limb fracture who were assessed fewer than 2 weeks after their injury and followed up for 6 months. Their medical records were reviewed 3 years later to see whether chronic pain was present.

One patient developed CRPS. This patient had both a positive finger perception and body scheme test at the baseline assessment. Three patients had persistent pain, and two of those had positive finger perception and body scheme tests. The remaining 43 patients did not have persistent pain, and four of these patients had positive finger perception and body scheme tests. This means that 7 out of the 47 patients would be flagged very early on for further assessment and possible treatment, Dr. Shenker observed.

Future plans are to refine a quicker test for body scheme assessment and to perform a larger prospective multicenter study.

Dr. Shenker has received grant or research support from the British Medical Association, the U.K. National Institute for Health Research’s Clinical Research Network, and the Cambridge Arthritis Research Endeavour.

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