Thien Ngo MD PGY – 3 UK PM&R 5/22/2012 Advisors: Drs. Lumy Sawaki & Oscar Ortiz

Outline  Introduction  Revised proposed objectives from 2011  Method  First Set of Result  Discussion  Timeline Revision  References

Introduction 1  Pain is a subjective experience, and its measurement has been traditionally based on self reported instruments.  Absence of objective instruments  Quantitative sensory testing and nociceptive flexion reflex (NFR) threshold have been explored as options to measure pain more objectively

Introduction 2  NFR in theory  The NFR is a polysynaptic spinal reflex subserving withdrawal from potentially noxious stimuli.  Provide indirect evidence of supraspinal modulation  The higher the threshold the more inhibition of spinal nociceptive transmission

Introduction 3  NFR threshold is defined by the lowest noxious stimulation intensity required to trigger a reflex motor response in the biceps femoris muscle.

Introduction 4 Central hyperexcitability as measured with nociceptive flexor reflex threshold in chronic musculoskeletal pain: a systematic review. Lim EC, Sterling M, Stone A, Vicenzino B. Pain Aug;152(8): Epub 2011 Apr 27

Introduction 5  Promising results in multiples experimental studies.  Reliable, reproducible, and correlated well with clinical findings within subjects  Significant variability between subjects, despite efforts for standardization, makes it unsuitable for clinical use or establishment of normal values.

 Propose alternative standardized method to measure NFR that avoid variability (mostly due to changes in skin resistance). Introduction 6 NFRI = Sural SNAP amplitude using NFRT stimulus Sural SNAP amplitude (supramaximal) x 100

Objectives  The goal of this pilot study is to begin to establish normative data of NFRI in young male adults. Our proposed study has 2 specific aims:  Specific Aim #1:Identify the sural nociceptive flexion reflex threshold (NRFT) and the sural nociceptive flexion reflex index (NFRI) in male adults of 20 to 40 years of age.  Specific Aim #2:Measure the correlation between the NFRI and level of pain as measured by Visual Analogue Scale (VAS).

Experimental Design  Recruitment: Flyers and volunteer subjects  Screening process and informed consent  Inclusion Criteria:  Healthy male  Exclusion Criteria:  Avoiding confounding factors of NFR and NFRT recording  Head injury, alcohol/drug abuse, psychiatric illness, on psychiatric/pain medications, neurological disorder, chronic pain, h/o cancer, and peripheral neuropathy

Method (Step 1) (Sural sensory nerve action potential)

EMG Machine

Method (Step 2) (Nociceptive Flexion Reflex)

EMG machine - Biceps Femoris Reflex

Method (Step 3) Nociceptive Flexion Reflex Index

EMG machine – NRFI

First Set of Result  SNAP – 28 mAmp  NFR – 28 mAmp  NFR Index – 100%  VAS - 45 mm (range mm)

Future outlook: Timeline - June 2012 – May 2013: recruiting and obtaining ten sets of data - June 2012 – May 2013: will compare with VA research for age group of May Present comparison between the two population

References  1.) Giorgio, S. et al. “The lower limb flexion reflex in humans”. (2005) Progress in Neurobiology 77:   2.) Rhudy, J. & France, C. “Defining the nociceptive flexion reflex (NFR) threshold in human participants: A comparison of different scoring criteria”. (2007) Pain 128:   3.) France, C. et al. “Using normalized EMG to define the nociceptive flexion reflex (NFR) threshold: Further evaluation of standardized NFR scoring criteria”. (2009) Pain 145:   4.) Terry, E. et al. “Standardizing procedures to study sensitization of human spinal nociceptiveprocesses: Comparing parameters for temporal summation of the nociceptive flexionreflex (TS-NFR)”. (2011) International Journal of Psychophysiology 81:   5.) Micalos, P. et al. “Reliability of the nociceptive flexor reflex (RIII) threshold and association with Pain threshold”. (2009) Eur J Appl Physio 105:

Thank you!