A Novel Tool for the Assessment of Pain: Validation in Low Back Pain

Joachim Scholz and colleagues develop and validate an assessment tool that distinguishes between radicular and axial low back pain.


Quality
Which of the following words would you choose to describe your pain?

Touch
Use two von Frey filaments, of 2 g and 26 g strength, and apply each filament 4 times.

8.1
Consider the sense of touch intact (no decrease), when 3 out of 4 stimulations with a filament produce a normal response.

8.2
Record touch-evoked pain, when 3 out of 4 stimulations with a filament provoke pain.

Blunt pressure
Press the blunt eraser end of a pencil (diameter 5-8 mm) onto the skin so as just to indent the skin. Hold the pencil in this position for 10 seconds. The end of the pencil must not be made of metal to avoid the sensation of cold. 10.

Brush movement
Move a make-up powder brush (width 1 cm) 3 times lightly over the skin, at 3-5 cm per second in a constant direction. Record a decreased response to brush movement, when it is reproduced in 2 of the 3 movements. 10.1 10.2 Record brush movement-evoked pain, when pain is elicited by 2 out of the 3 movements. 11.

Vibration
Place a standard tuning fork (128 Hz) with and without vibration on a prominent bone in the body area affected by the pain. 11.1 Response to vibration is decreased when the patient cannot differentiate between a vibrating and a nonvibrating tuning fork. 12.

Pinprick
Use a medium-size safety pin and indent the skin with enough pressure to elicit a painful response on normal skin without leaving a mark.
12.1 The response to pinprick is decreased, when the patient describes only touch without a pricking sensation or no sensation at all in 3 out of 4 stimulations. 12.2 Record the intensity of the pain if it exceeds the intensity of the normal painful response to pinprick in the reference area in 3 out of 4 stimulations.

Warm temperature
Apply a warm stimulus by holding a brass bar or a thermode (diameter 10-15 mm) of 40°C (104°F) temperature onto the skin for 10 seconds. Do not apply pressure. 14.
Cold temperature Hold a brass bar or a thermode (diameter 10-15 mm) of 20°C temperature onto the skin for 10 seconds. Do not use pressure. 15.

Temporal summation
Apply the stronger von Frey filament (26 g) repetitively on the skin at a rate of 1-2 times per second for 30 seconds. Two positive outcomes are possible: 15.1 Although the first stimulus does not produce pain, pain occurs during repeated stimulation. 15.2 A painful response evoked by the first stimulus increases in intensity during repeated stimulation. Record a negative test result if the pain intensity does not increase beyond the intensity of the initial painful response. 16.

Straight-leg-raising test
This test should only be performed in patients with back pain or pain in the lower extremities.
16.1 Raise the affected leg extended at the knee to a 90° angle unless elevation is limited by pain. Repeat the test, this time elevating the affected leg flexed at the knee. Reproduce the symptoms by raising the affected leg once again extended at the knee. Consider only pain in a radicular distribution as a positive result, i.e. pain projecting into a leg dermatome (above or below the knee) when the leg is elevated extended at the knee. Pain caused by a radiculopathy usually decreases or is absent when the affected leg is raised with the knee flexed.