Complex Regional Pain Syndrome

Procedure

Compare skin temperature of the affected limb with the same area on the other limb, using the back of your hand or an infrared thermometer, at several matched points.

Positive Finding

The affected limb feels or measures warmer or colder than the other side.

Interpretation

One of the vasomotor signs in the Budapest criteria. Early CRPS is often warm and later CRPS cool, but this varies. Suspected CRPS needs early medical referral for diagnosis and pain management; meanwhile, keep the limb moving gently within comfort and avoid forceful or painful passive stretching. In a study of 113 people with CRPS and 47 people with other nerve pain (Harden 2010), a temperature difference felt by hand was found on examination in 69% of the people with CRPS and 15% of the others. CRPS in that study was diagnosed with criteria that include this sign, so these numbers overstate how well the sign works on its own and are not shown as accuracy figures. Diagnosis uses the Budapest criteria, which combine symptoms and signs from four categories (sensory, vasomotor, sweating/swelling, motor/trophic).

Procedure

Measure limb circumference at matched landmarks on both sides, or use water-displacement volumetry for the hand or foot. Repeat over time.

Positive Finding

Swelling of the affected limb compared with the other side.

Interpretation

One of the sweating/swelling signs in the Budapest criteria. Swelling has many causes, so rule out infection, DVT and fracture-related swelling first. In a study of 113 people with CRPS and 47 people with other nerve pain (Harden 2010), one-sided swelling was found on examination in 64% of the people with CRPS and 24% of the others. CRPS in that study was diagnosed with criteria that include this sign, so these numbers overstate how well the sign works on its own and are not shown as accuracy figures. Diagnosis uses the Budapest criteria, which combine symptoms and signs from four categories (sensory, vasomotor, sweating/swelling, motor/trophic).

Procedure

Compare skin colour of the affected and unaffected limbs in good light, with both limbs at the same height.

Positive Finding

A colour difference: red, blue, pale or mottled on the affected side.

Interpretation

One of the vasomotor signs in the Budapest criteria. Colour can change from visit to visit, so record it each time. In a study of 113 people with CRPS and 47 people with other nerve pain (Harden 2010), a skin colour difference was found on examination in 84% of the people with CRPS and 36% of the others. CRPS in that study was diagnosed with criteria that include this sign, so these numbers overstate how well the sign works on its own and are not shown as accuracy figures. Diagnosis uses the Budapest criteria, which combine symptoms and signs from four categories (sensory, vasomotor, sweating/swelling, motor/trophic).

Procedure

Look and feel for differences in sweating between the affected and unaffected limbs, in a comfortable room temperature.

Positive Finding

More or less sweating on the affected side.

Interpretation

One of the sweating/swelling signs in the Budapest criteria. Seen less often than temperature or colour change, so its absence does not count against CRPS. In a study of 113 people with CRPS and 47 people with other nerve pain (Harden 2010), a sweating difference was found on examination in 44% of the people with CRPS and 11% of the others. CRPS in that study was diagnosed with criteria that include this sign, so these numbers overstate how well the sign works on its own and are not shown as accuracy figures. Diagnosis uses the Budapest criteria, which combine symptoms and signs from four categories (sensory, vasomotor, sweating/swelling, motor/trophic).

Procedure

Compare hair growth, nails and skin texture of the affected and unaffected limbs.

Positive Finding

Changed hair growth, nail changes (ridged, brittle, faster or slower growth) or shiny, thin skin on the affected side.

Interpretation

One of the motor/trophic signs in the Budapest criteria. Hair changes on their own are not a reliable sign. In a study of 113 people with CRPS and 47 people with other nerve pain (Harden 2010), any trophic change (hair, nail or skin) was found on examination in 69% of the people with CRPS and 30% of the others. CRPS in that study was diagnosed with criteria that include this sign, so these numbers overstate how well the sign works on its own and are not shown as accuracy figures. Diagnosis uses the Budapest criteria, which combine symptoms and signs from four categories (sensory, vasomotor, sweating/swelling, motor/trophic). Hair changes on their own were seen slightly more often in the comparison group (67%) than in CRPS (55%).

Procedure

Measure active and passive range of the affected joints and compare with the other side. Look for weakness, tremor and abnormal postures (dystonia) of the hand or foot.

Positive Finding

Reduced active range, weakness, tremor or dystonia on the affected side.

Interpretation

One of the motor/trophic signs in the Budapest criteria. Do not force passive range: painful stretching can worsen CRPS. Also test for allodynia (pain to light touch) and hyperalgesia (increased pain to pinprick), which form the sensory category of the criteria. In a study of 113 people with CRPS and 47 people with other nerve pain (Harden 2010), reduced active range of motion was found on examination in 80% of the people with CRPS and 38% of the others. CRPS in that study was diagnosed with criteria that include this sign, so these numbers overstate how well the sign works on its own and are not shown as accuracy figures. Diagnosis uses the Budapest criteria, which combine symptoms and signs from four categories (sensory, vasomotor, sweating/swelling, motor/trophic).