CSB464 Neurology - Pain and Analgesia (Part 1) PDF

CSB464: NEUROLOGY PAIN AND ANALGESIA (PART 1) WHAT IS PAIN? Tony Hall FSHP  COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you by or on behalf of the Queensland...

CSB464: NEUROLOGY PAIN AND ANALGESIA (PART 1) WHAT IS PAIN? Tony Hall FSHP  COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you by or on behalf of the Queensland University of Technology pursuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice 3  What is Pain ? 4  “An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage,”  expanded upon by the addition of six key notes and the etymology of the word pain for further valuable context:  Pain is always a personal experience that is influenced to varying degrees by biological, psychological, and social factors.  Pain and nociception are different phenomena. Pain cannot be inferred solely from activity in sensory neurons.  Through their life experiences, individuals learn the concept of pain.  A person’s report of an experience as pain should be respected.  Although pain usually serves an adaptive role, it may have adverse effects on function and social and psychological well-being.  Verbal description is only one of several behaviours to express pain; inability to communicate does not negate the possibility that a human or a nonhuman animal experiences pain.  Etymology:  Pain =Middle English, from Anglo-French peine (pain, suffering), from Latin poena (penalty, punishment), in turn from Greek poine (payment, penalty, recompense). IASP 2020 Notes:  Experiences which resemble pain but are not unpleasant, e.g., pricking, should not be called pain. Unpleasant abnormal experiences (dysesthesias) may also be pain but are not necessarily so because, subjectively, they may not have the usual sensory qualities of pai n  What is Pain ? 5  Pain is also “what the patient says it is, existing where and when the patient says it does.” attributed to Dame Cicely Saunders  Pain can be an expression of emotional or spiritual suffering as well as a physical symptom  Acute Pain 6  Acute Pain 7  Acute pain serves as a warning system of potential or actual injury  So what happens in Acute pain? 8  Awareness of potential damage through nociceptive pathways  Activation of sympathetic nervous system (“Fight or Flight”)  Escape/removal Followed by  Activation of parasympathetic nervous system (“Rest and Digest”)  Down regulation of nociceptive pathways  Pain reduces over a short period of time and disappears  Retention of memory of painful experience to avoid similar situations in future  Do we need acute pain? 9  Yes!  Individuals learn to avoid tissue damage in the future  Some individuals experience no pain – CIP or congenital insensitivity to pain associated with disorder of the voltage- gated sodium channel SCN9A (Nav1.7)  Others have a genetic deficiency in the enzyme FAAH (fatty- acid amide hydrolase), which breaks down the neurotransmitter anandamide (Sanskrit for ‘bliss’) so such people not only feel less pain, they also feel less anxiety about this pain  Unfortunately, pain insensitivity is associated with an expectation of reduced life duration  Chronic Pain: Definition 10  Pain with a duration of 3 months or greater  Often associated with functional, psychological and social problems that can negatively impact a person’s life.  Chronic Pain 11  Often associated with functional, psychological and social problems that can negatively impact a person’s life. (TORTURE AND SUFFERING)  Acute vs Chronic Pain 12  Acute:  Chronic  “useful” warns of potential  “useless pain” tissue damage  Associated with acute on  Trajectory chronic flares of pain Time -→  Pain Prevalence: Overseas studies 13  Canadian telephone survey of 500 Households: Are you or any member of your family over 18 frequently troubled with pain? Yes 11% (Crook et al. Pain 1984)  Swedish postal survey of 980 individuals: Age range 18-84. 33% No pain problem. 22% continuous obvious pain the majority with > 6months duration... (Brattberg et al. Pain 1989)  Denmark postal survey, 4000 individuals: 30% persistent pain (Anderson et al. Pain 1987)  The Prevalence of Pain Complaints in a General Population: An Australian Study 14 The results of a random telephone survey Brisbane, Australia. 1986. Simon Strauss, Fiona Guthrie and Fred Nicolosi Australian Association of Musculoskeletal Medicine Bulletin Vol 9: 3 December 1993.  Impact of Chronic Pain 15  Pain is a common problem  affecting ~20% of individuals in Australia  more than 50% of elderly persons living in the community  more than 80% of residential aged care patients  Prevalence of Chronic Pain in Qld 2007 16 Figure 2-5: Prevalence of Chronic Pain, QLD, 2007 Age Gp Males Females 40000 15-19 8.0 11.6 35000 Males 20-24 11.7 13.8 30000 Females 25-29 10.7 11.9 25000 30-34 14.0 13.1 20000 15000 35-39 16.6 16.3 10000 40-44 18.2 16.1 5000 45-49 19.6 23.7 0 50-54 19.1 27.6 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85+ 55-59 26.0 29.3 60-64 22.8 28.0 65-69 27.0 29.3 70-74 20.5 27.2 75-79 21.0 26.0 80-84 18.7 31.0 85+ 18.7 20.0 Total 19.5 23.2 Source: Australian Bureau of Statistics 2008 Pain prevalence increases with age  10% of 30 year old  25% of 50 year old  45% of >60 year old  Over the age of 30 the prevalence of pain in females is twice that in males  Why does pain affect these pain groups more than elderly ? Prevalence of Chronic Pain intensity Intensity 0% 20% 40% 60% Mild Discomforting Distressing Horrible Excruciating 45% can be said to be suffering severe pain Chronic Pain - site prevalence 40.00% 30.00% 20.00% 10.00% 0.00% % Arm Other Chest Leg Head & Neck Back Back pain is one of the most common ailments seen by GPs 90 Prevalence (%) of back 79.2 80 70 64.6 60 50 40 30 25.5 20 10 0 Point prevalence 6-month prevalence Life-time prevalence 5% of GP consultations are for low back pain ~10% of GP consultations are related to pain Walker 2002. Jensen S 2004 Back pain is a leading cause of days lost to work and disability 45 42.6 In any 6-month period Proportion of respondents (%) 40 ~10% of Australian 35 adults suffer significant 30 disability from low back 25 pain 20 15 10.9 10.5 10 5 0 Low intensity/low disability High intensity/low disability High intensity/high disability Mean time off from usual activities = 1.6 months Walker, 2002. Socioeconomic Consequences  Inability to work  Inability to carry out ADLs  Loss of ‘worth’  Loss of self esteem  Greatest effect in 45-60 age groups  $ Work Cover claims and payouts (21.4% work related injuries, 18.8% related to an accident, ? NDIS applications)  $ in Medicare support Other impact  Sleep disturbance  Mood  Depression in ~ 50% patients  Suicidal ideation in ~ 20%  Health status reduced  Unable to exercise (3.4% sport related injury)  Deconditioning What are desired outcomes of treatment?  Return to active movement  Persistent pain does not = damage  Maintenance of AODL Intensity  Can’t cure persistent pain  Maintain pain stability and this will lead to reduction in neural sensitisation 0% 20% 40% 60%  Try and maintain pain at a bearable level Mild Discomforting Distressing Horrible Excruciating Pain Scores Mild=1-3, Bearable =4-5, Distressing 5-6, Horrible 7-8, excruciating 9-10