Clinically it is important to distinguish between the three main pain mechanisms that may present with our patients experiencing chronic pain (Nijs et al 2014). Here I describe my clinical findings in two chronic low back pain patients, one with chronic nociceptive pain and the other with chronic central pain mechanisms.
Unlike nociceptive pain, central sensitisation has been found in various contemporary studies to be associated with sensory processing alterations (e.g. Ling et al 2007; Wand et al 2011,2013; Berryman et al, 2013; ) and anxiety (Vancleef and Peters 2008, Rosemarin et al 2009; Ansari and Derakshan 2011; Hashmi et al 2013). Trait sensory processing can be measured using the Adolescent/Adult Sensory Profile (Brown et al 2001) which measures a person's natural neural thresholds for sensory input and their behavioural response to their sensory requirements, as a trait characteristic.
Trait Anxiety can be measured using the Trait Anxiety Inventory (Spielberger 1968) and measures a person's enduring characteristic indicative of differences in individuals’ proneness to reactions of state anxiety when faced with a perceived threat. Both trait anxiety and trait sensory profiles can indicate heightened sensitivity to sensory stimuli. A recent pilot study shows relationships between trait anxiety, trait sensory sensitivity and central sensitisation (presented at the Pain in Motion Colloquium 2015). This case study demonstrates the difference in trait anxiety and sensory profiles in two chronic low back pain patients the clinic.
Questionnaires administered to both cases: Central Sensitisation Inventory (CSI; Mayer et al 2012), Adolescent/ Adult Sensory Profile, Trait section of the State-Trait Anxiety Inventory (T-STAI) and Marlowe-Crowne Social Desirability Questionnaire (Crowne and Marlowe 1960; which identifies people who are more likely to under-report socially undesirable information about themselves).
29 year old male. Years of insidious chronic low back pain, no structural fault identifiable. Pain distribution is rarely anatomically plausible. Initial past medical history includes ankle fracture, apparently followed by CRPS that has resolved; multiple general anaesthetics; a concussion. Now complains of "showers of fizzing " in arms and legs with no particular aggravating / easing factors. Develops extreme levels of pain when incurs any acute injury (such as a recent laceration injury in which a slim piece of steel was shot into his arm, and subsequently a fractured finger, both work accidents.) Works full time in a manufacturing plant. Very fatigued by end of day and complains of feeling "weird in my head, I can't describe it." Poor sleep due to, "my brain feels as though it's buzzing and can't calm down." NSAID medication does not help. Regularly attends local gym and self reports as being competitive. Has attended pain clinics in the past.
CSI: 78 (very highly central sensitisation)
Sensory profile: Much more than most on sensory hypersensitivity and sensation avoiding, and much more than most in some areas on hyposensitivity (extreme ranges of abnormal sensory processing.) On further questioning he has been diagnosed with dyspraxia as an adolescent. Dyspraxia is associated with sensory processing abnormalities and sensorimotor dysfunction (Davies 1999).
Coping style: High Trait Anxiety (and low defensiveness.) Abnormal sensory sensitivity has been correlated with trait anxiety (Engel Yeger and Dunn 2008).
Objective Sensory-motor tests using neurodevelopmental sensory-motor test techniques on the basis of abnormal sensory processing profile:
Midline Crossing -Cross crawl test - after 8 repetitions began to experience his "fizzing" symptoms in his legs with "buzzing in my brain" (similar to "feelings of peculiarity" noted in Daenen et al 2012). These stopped as soon as he terminated the test.
Test was repeated using ipsi-lateral movements instead of contra-lateral - no symptoms produced.
Oculomotor tests - smooth pursuit eye tracking, sitting - after 4 sweeps he experienced increasing left arm pain. Sitting without eye tracking, no arm pain. Eye tracking repeated in supine - minimal symptoms. Symmetric Tonic Neck Reflex test in four-point kneeling - neck flexion and extension reproduced fizzing in the legs and back and buzzing in the brain. These symptoms were cleared after 10 seconds of lying supine with ear muffs on and eyes closed with the aim of reducing sensory input and overload.
All these tests appear to produce symptoms that are a result of sensory processing difficulties. Diagnosis: central pain mechanisms associated with sensory processing abnormalities, augmented by attention to symptoms associated with high anxiety (Eysenck's attentional control theory, 2007) . I suggest sensory-motor training and pain education.
32 year old male, full time worker as a fitness trainer, injured lower back (Lx) and sacroiliac joint (SIJ) region during a dead-lift at the gym 12 months ago. Has tried multiple treatments involving acupuncture, core strengthening exercises, osteopathic manipulation. Pain remains in the Lx spine, SIJ and left quadratus lumborum, sometimes swaps sides at the thoraco-lumbar junction. NSAID medication does partially help but prefers not to use them often. Pain aggravated by walking, running, carrying unilateral loads. Activities - Surfing, but has noticed he always falls off to the same side! Very busy and stressed lifestyle, frustrated at lack of resolution of pain. History includes 3 significant concussions.
CSI - 47 (sensitised)
T-STAI - 41 and MC-5 - normal ranges of high trait anxiety and defensiveness coping style.
Sensory Profile - all within normal range except higher than normal on hypo-sensitivity sensory profile, meaning he needs more stimulus than most people to function normally (according to Brown et al 2001)
Motor control tests: Failure of load transfer tests through the left SIJ (Hungerford et al 1999), poor control of lumbo-pelvic rotation and poor awareness of the local stabiliser muscles of the lumbo-pelvic region i.e. Transversus, psoas and multifidus; high activity in quadratus lumborum.
Diagnosis: chronic pain of mainly nociceptive origin associated with lack of motor control of the SIJ and Lx spine into rotation and in weight bearing. I suggest motor control retraining with increased sensory input and feedback to address his hyposensitivity sensory profile.
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Neblett, R., Cohen, H., Choi, Y., Hartzell, M. M., Williams, M., Mayer, T. G. and Gatchel, R. J. (2013) 'The Central Sensitization Inventory (CSI): Establishing Clinically Significant Values for Identifying Central Sensitivity Syndromes in an Outpatient Chronic Pain Sample. The Journal of Pain, 14(5), 5//, pp. 438-445.
Spielberger, C. D., Gonzalez, H. P., Taylor, C. J., Algaze. B. & Anton, W. D. (1978). Examination stress and text anxiety.In C. D. Speilberger & I. G. Sarason (Eds), Stress and anxiety, Vol. 5. Hillsdale. NJ: Lawrence Erlbaum Associates Ltd.