PAINWHY, AND WHAT TO DO ABOUT

IT…Kenneth N. Schikler, MD, Department of Pediatrics, Division of Pediatric

RheumatologyUniversity of Louisville School of Medicine

CHILDHOOD PAIN SYNDROMES

• 25% of all new patients seen by pediatric rheumatologists

• 75% female

• Average age of onset 12 years

Pediatric Rheumatology Database Group J Rheum 23(11)1968-74, 1996

MUSCULOSKELETAL PAIN

• Population based survey of >6600 children and adolescents in Netherlands

• 82% response rate

• 25% reported chronic pain

• Of that group 57% consulted MD

Ref: Perquin,et al. Clin J Pain,2000

MUSCULOSKELETAL PAIN (MSP)

• 6% of visits to a pediatric primary clinic of children>3 y/o was for MSP¹

• Low back pain 1 month prevalence in UK among 1496 students 11-14 years old was 24% (pain for >1 day), 94 % reported disability via a disability questionairre²

¹ De Inocencio. Pediatrics, 1998

² Watson. Arch Dis Child, 2003

PAIN IS NO FUN, BUT…

PAIN IS

• An unpleasant sensory and/or emotional experience associated with actual or potential tissue damage

• It is a protective early warning system to alert us to adjust what we are doing in order to assess whether harm or damage might occur

PAIN

• Physical recognition of unpleasant stimulus, and…

• The Cerebral/emotional recognition and response to the unpleasant stimulus

DEALING WITH THE CEREBRAL/EMOTIONAL

DEALING WITH THE CEREBRAL/EMOTIONAL SIDE OF PAIN

• Until one is sure that they are safe from harm or damage from an unpleasant stimulus (pain), fear and anxiety complicate and heighten the unpleasant reaction, until someone we trust to have our welfare in mind and is knowledgeable and can reassure us that we are safe, the painful experience and response to it continues at maximal levels

DEALING WITH THE CEREBRAL COMPONENT OF PAIN

• The highly motivated individual even when “unaware” of an unpleasant stimulus may “ignore” it until the motivation diminishes

• Examples: athletes, First Responders, military personnel in action or friends or family members in emergencies

• Often function without conscious recognition of pain until their “need to function” passes

PAIN : TYPES

• Nociceptive

• Neuropathic

• Central Pain Processing (Central Sensitization)

NOCICEPTIVE PAIN

• When nerve endings are stimulated to the point approaching a harmful level

• Thermal: temperature extremes

• Mechanical: crushing, tearing, piercing of non-nerve tissue

• Chemical: salt in a wound

NEUROPATHIC PAIN

• Insult to portions of a nerve typically with a tingling, burning, “pins and needles” sensation, or a “shooting pain”

• Obstructive blood flow to a nerve from pressure (hand falling asleep or dysautonomia)

• Direct trauma (bumping funny bone)• Diseases that affect the nerve

CENTRAL PAIN PROCESSING

• Heightened sensitivity of the areas within the brain that alert us to potential damage at intensity levels that typically would not provoke those pain centers to “activate”

• When activated in addition to arousing recognition of pain, the physiologic responses to pain are triggered, altering the Autonomic Nervous System’s behavior

INFLAMMATORY ARTHRITIS & PAIN

• IL-1

• IL-6

• TNF-

• MMP’s

JIA, CYTOKINES & PAIN

• Cytokines in the joint have a direct effect on nerve endings, and also on the joint lining and cartilage causing inflammation and swelling. This puts mechanical pressure on nerve endings in addition to the direct chemical nerve stimulation and promotes other pain inducing substances

• Within the central nervous system these cytokines and other chemicals make the pain centers more “alert” to pain

PAIN & INFLAMMATORY ARTHRITIS: TREATMENT

• Treatment aimed at minimizing the bradykinin, Substance P, prostaglandins, MMP’s, and pro-inflammatory cytokines

• NSAID’s

• Acetaminophen

• DMARD’s

• Biologics

• Moderate exercise

N-METHYL-D-ASPARTATE (NMDA)

CHRONIC MSK/CENTRAL PAIN PROCESSING & RELATED DISORDERS

• Fibromyalgia

• Chronic Fatigue

• Migraine

• Irritable Bowel Syndrome

• TMJ disorders

• Mood Disorders

• Complex Regional Pain Syndrome (RSD)

• Chronic Pelvic Pain

• Premenstrual Syndrome

• Myosfascial Pain syndromes

• Multiple Chemical Sensitivities

• Chronic cystitis

• Dysautonomia/ POTS

History of widespread pain has been present for at least 3 months

Definition: Pain is considered widespread when all of the following are present:

• Pain in both sides of the body

• Pain above and below the waistIn addition, axial skeletal pain (cervical spine, anterior chest, thoracic spine, or low back pain) must be present. Low back pain is considered lower segment pain.

Pain in 11 of 18 tender point sites on digital palpation

Definition: Pain, on digital palpation, must be present in at least 11 of the following 18 tender point sites

Digital palpation should be performed with an approximate force of 4 kg. A tender point has to be painful at palpation, not just "tender."

The American College of Rheumatology 1990 Criteria for the Classification of FM[13,25]

JUVENILE FIBROMYALGIA (JFS)

• Widespread MSP for at least 3 months

• ≥ 5 well-defined tender points

• 3 of 10 minor criteria

• ≤age 16 at onset

• If 5 minor criteria present only 4 tender points needed

Ref: Yunis & Masi. Arthritis Rheum;28(2):138,1985

JUVENILE FIBROMYALGIA: MINOR CRITERIA

• Fatigue

• Sleep problems

• Anxiety/ tension

• Subjective swelling

• Numbness/tingling

• Lightheadedness/ dizziness

• Chronic headache• Irritable Bowel

syndrome• Pain modulated by

stress• Pain modulated by

weather• Pain modulated by

physical activity

JUVENILE FIBROMYALGIA

• 1756 school-aged (pre-adolescent) Finnish children prospectively studied by questionnaire then PE; 1.3% prevalence

• 338 healthy Israeli 9-15 y/o students studied; 6.2% prevalence

• 1.3% healthy Mexican 9-15 y/o students

• 1 in 6 people with fibromyalgia are less than 18 years old

NEW ACR CRITERIA FOR FIBROMYALGIA (PRELIMINARY)

• Remove tender points from criteria as the central element

• Quantitate widespread pain with widespread pain index (WPI)

• Incorporate key symptoms

• Provide symptom severity scale (SS)

Ref: Arthritis Care Res;62(5):600-10,2010

FIBROMYALGIA & RCBF

• Fibromyalgia patients and controls detect sensory stimuli at the same levels (electric, thermal, mechanical)

• Level at which stimuli become noxious is ~twice as high for controls

• Similar stimuli produce significant differences in regional Cerebral Brain Flow; >2x’s in pts vs controls, particularly in the Anterior Cingulate Cortex

FMS : RCBF

CENTRAL PAIN PROCESSING DISORDERS & CATASTROPHIZING

• Responses that characterize pain as being “awful” “horrible”, “unbearable”

• Found to be independent of Depression• May influence intentional focus on painful

or potentially painful events• Increases pain-related fear leading to

increased attention to stimuli and amplifying perception of pain

• rCBF similar to that found in Fibromyalgia

CATASTROPHIZING & RCBF

MOOD STRESS & THE BRAIN

FIBROMYALGIA & OTHER CENTRAL PAIN SYNDROMES:

TREATMENT

• Validation

• Education

• Pharmacologic

• Aerobic Exercise

• Cognitive Behavior Therapy

• Alternative Therapies

VALIDATION & EDUCATION

• Acknowledge the presence of discomforting symptoms of these conditions (not diseases)

• Provide an explanation for our understanding of how these mechanisms occur

• Prevent “sick mode” identification

SLEEP HYGIENE

• Bed is for sleep only

• No naps

• Regular bedtime

• No vigorous exercise within 2 hrs of bedtime

• No more than 30 minutes of sleeplessness in bed

• Relaxation, self-guided imagery techniques

COGNITIVE BEHAVIORAL THERAPY

• Modules of pain management, psycho-education, sleep hygiene & ADL’s

• Instruction in cognitive restructuring, distraction, relaxation and self-reward

• Minimize catastrophizing style of coping• Focus on regaining function via

developing self-management skills

EXERCISE (I)

• Aerobic nearly universally beneficial; tolerance, compliance, adherence are biggest issues

– To maximize benefits:– Both physician and patient should consider this as a

“drug”– Assure physiologic capability ( eg exclude EIA)

– Review/instruct in how to measure heart rate/pulse

– Review availability of access to aerobic exercise equipment in home

PHARMACOLOGIC TREATMENT OF CENTRAL PAIN

• Antidepressants– Mixed norepinephrine/serotonin reuptake inhibitors

• Anticonvulsants– Alpha-2-delta (α2δ) ligands

• Opioid receptor antagonists• Future

– Central alpha-2-adrenergic agonist– Dopamine receptor agonists– NMDA receptor antagonists– NK-1 receptor antagonist– GABA receptor agonists– Vitamin D (??)