///2010 Abstract Details
2010 Abstract Details2018-05-01T17:52:49+00:00

Diffuse Noxious Inhibitory Control (DNIC) to evaluate endogenous pain modulation: a longitudinal study in healthy women to test reliability of repeated measures

Abstract Number: 100
Abstract Type: Original Research

Ruth Landau MD1 ; Hilary Wilson PhD2; Sebastian U Ruehlmann MD3; John C Kraft BSc4; Lisa Y Flint BSc5; Brendan Carvalho MBBCh, FRCA, MDCH6

Background

Diffuse noxious inhibitory control (DNIC) is a technique developed to characterize an individuals capacity to modulate pain using the premise that pain inhibits pain in a remote area of the body. DNIC may provide insight into the risk of developing chronic pain (1). The reliability of DNIC within the same testing session has been demonstrated (2), but reliability over longer time intervals with repeated measures has not. This study evaluates the test re-test reliability of DNIC and pain tolerance (max pain tolerated) over a 7-month interval in healthy women. Due to potential hormonal influences, measures were assessed at the follicular phase of the cycle.

Methods

30 non-pregnant female volunteers will be enrolled into this longitudinal multi-center study, studied during 4 menstrual cycles. DNIC test description: A 3cm heat thermode at 43-48˚C (Medoc ATS Thermode) is used to invoke a test stimulus pain response of 6 out of 10 (T˚6) on the volar part of the dominant forearm. A hot water bath (46.5˚C) is used for the conditioning stimulus on the non-dominant hand. The DNIC score is calculated as the difference between the test stimulus pain rating before and after the conditioning stimulus. A negative DNIC score is indicative of efficient pain inhibition. The same heat thermode is used to determine pain tolerance (max T˚ tolerated). Descriptive statistics were calculated for DNIC and pain tolerance scores, and intraclass coefficient statistic (ICC) calculated for assessing reliability. The ICC is a reliability measure that produces a test of equal means; a significant finding (p<0.05) supports the test re-test reliability of the measure.

Results

25 of 30 volunteers are enrolled in this ongoing study. Analysis was performed on data from 25 women for 1 cycle and 19 women for 2 cycles. The ICC was excellent for pain tolerance, T˚6 and water bath scores, and very good for DNIC scores (Table).

Discussion

Our findings demonstrate the stability of repeated measures of DNIC and pain tolerance tests. This study shows the feasibility and reliability of assessing changes in DNIC over time in women during the follicular phase of the menstrual cycle. As such, DNIC may serve as an important clinical tool to evaluate the hormonal effects (menstrual cycle, pregnancy) on pain inhibition as well as to facilitate the prediction of post-cesarean pain or the risk of chronic pain development.

1.Curr Opin Anaesthesiol 2009; 22:425-30

2.Pain Res Manag 2009; 14:433-8



SOAP 2010