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A Case of Back Pain Note: These notes were written based on last year’s teaching. As such, we cannot guarantee that they are accurate/ representative of the information you will be tested on. Please refer to your pre-reading, in-session work, and post-reading to prepare thoroughly for the exam. Part 1 Pre-reading Causes of back pain • Injury – e.g. pulled muscle/ strain • Medical conditions – e.g. slipped disc, sciatica (trapped nerve) or ankylosing spondylitis • Sign of a serious problem (very rare) – e.g. broken bone, cancer or infection How to relieve back pain • Stay active and continue daily activities • Anti-inflammatory medicine (e.g. ibuprofen) • Ice pack to reduce pain and swelling • Heat pack to relieve joint stiffness or muscle spasms • Doing some exercises and stretches (e.g. walking, swimming, yoga, pilates) • Do NOT stay in bed for long periods (aka immobility) When to consider medical advice • Does not improve after a few weeks • Stops patient from doing day-to-day activities • Pain is severe or getting worse over time • Worried about the pain and struggling to copeWhen to ask for an urgent GP appointment/ call 111 • A high temperature • Unintentional weight loss • Lump or deformity in your back • Pain does not improve after resting or is worse at night • Pain is exacerbated when sneezing, coughing or pooing (aka when intra-abdominal pressure increases) • Pain is coming from the top of your back (between your shoulders), rather than your lower back When to go to the A&E/ call 999 • Pain, tingling, weakness, or numbness in BOTH legs • Numbness or tingling around genitals or buttocks • Difficulty urinating • Loss of bladder or bowel control • Chest pain • Started after a serious accident (eg. car accident) Treatments (prescribed by a GP) • Painkillers or medicine to relax back muscles (NB: paracetamol is not recommended on its own) • Group exercise classes, physiotherapy, manual therapy • Cognitive behavioural therapy – psychological support • Procedure to seal off some nerves in the back to stop them from sending pain signals (only for long-term lower back pain) When to refer to surgery • Back pain is caused by a medical condition (e.g. slipped disc) AND other treatments have not helpedThe Science of Pain 1. Somatotopic Arrangement • Different areas of the somatosensory cortex correspond to different areas of the body • Contralateral arrangement – the LEFT side of somatosensory cortex corresponds to the RIGHT side of the body, and vice versa 2. Affective Neuroscience Brain regions, when stimulated by signals, can initiate a physiological and motivational output Stimulation of the… Part of the brain Output Cingulate cortex Aversion Insula Vasoconstriction, sweating, increase in pulse rate Amygdala Fear Reticular Arousal formation3. Signal Transmission Transduction – process by which a stimulus (mechanical/ thermal/ chemical) is converted to an action potential Touch stimulus: • Touch (fine on wrist) is detected by touch and pressure receptors (e.g. Meissner’s corpuscles, Pacinian corpuscles, Ruffini endings, Merkel’s discs, low-threshold nerve endings) • Action potentials travel via the dorsal column medial lemniscus pathway Pain stimulus: • Nociceptors (pain receptors embedded on cell membranes of high- threshold neurons) • Requires a higher stimulus to initiate the action potential • Pain action potentials occur via the spinothalamic tractPain action potentials Pain action potentials occur via the spinothalamic tract (split into neospinothalamic and paleospinothalamic tracts) Neospinothalamic Paleospinothalamic Tract Tract Speed Fast Slow Type of pain Sharp Dull Carried by… A-delta fibres C fibres **note: neospinothalamic tract is FASTER because the A-delta fibres are MYELINATED 1. Neospinothalamic tract nociceptor à synapse at dorsal horn of spinal cord à decussates à synapse at thalamus à wrist portion of somatosensory cortex à SII region/ secondary somatosensory cortex (for visual integration) à insula (vasoconstriction, sweating, etc.)2. Paleospinothalamic tract nociceptor à synapse at dorsal horn of spinal cord à decussates à travels up spinal cord à reticular formation (arousal)** à thalamus à wrist portion of somatosensory cortex à cingulate cortex (aversion) + amygdala (fear) **note: this is why dull pain keeps you up at night Other types of receptors • Mechanoreceptors – cell surface receptors found on the plasma membrane of high threshold free nerve endings o Undergo a conformational change when a mechanical force is applied o Deformation allows ions to initiate an action potential • Thermal receptors – temperature-sensitive o Undergo a conformational change at certain thermal ranges, leading to an action potential • Chemoreceptors – inflammation-sensitive o Initiate an action potential in response to cytokines release at the site of inflammationMusculoskeletal reflex action • When we sense pain, the musculoskeletal reflex action occurs • This is due to the reflex arc at the spinal cord that directly connects to the appropriate muscles • E.g. When there is a pin prick on the wrist, the forearm muscles are activated, causing the person to flinch Note: Do refer to the consolidation images attached in Part 1 of the case, especially the last slide on types of receptors. Part 2 Identification of action potentials pathways How do you identify which action potential pathway the different types of pain takes? – process of elimination 1. Identify the correct side 2. Correctly identify which tract pain signals travel along – spinothalamic tract 3. Identify the correct character of pain (sharp/ dull) – sharp pain travels via A-delta fibres (does NOT cross the reticular formation), dull pain travels via C fibres (crosses the reticular formation) What pathway would an action potential take when there is a pin prick in the right hip? • Using the concept of contralateral control, when there is a pin prick in the RIGHT hip, the LEFT cortices are activated = eliminate all the right-sided options • Since the pain travels up the spinothalamic tract, the dorsal horn must form part of the pathway = purple pathway can be ruled out • As pin prick pain is sharp, it travels via A-delta fibres = does not cross the reticular formationReferred pain • Referred pain – pain perceived at a location other than the site of the painful stimulus o E.g. for a MI, pain is often felt in the left neck, shoulder, arm, and back instead of in the thorax • Convergence theory – visceral somatosensory neurons converge on the somatic afferent Differentials for back pain 1. Mechanical back pain – does not usually present with too many other neurological features, source of pain may be triggered by movements of the spine 2. Radiculopathy – most commonly due to age-related degeneration, produces a range of symptoms due to the pinching of a nerve root (pain is one-sided) 3. Cauda Equina Syndrome – typically presents bilaterally, and is a central problem due to disc prolapse causing compression of nervesCauda equina syndrome Symptoms • Bilateral neurogenic sciatica • Reduced perineal sensation (aka saddle paraesthesia) • Altered bladder function, leading to painless urinary retention • Loss of anal tone, resulting in faecal incontinence • Sensory dysfunction Spinal cord development • 8 weeks – the spinal cord and the vertebral column are roughly the same length • 24 weeks – lengthening of the vertebrae causes the spinal cord to shift upwards and results in the lengthening of the lower nerve roots, such as S1 • At birth – caudal region is opposite L3 region, and spinal nerve roots are further lengthened, forming the cauda equinaCES – common sites of nerve compression • L4/L5 and L5/S1 are the most common sites of nerve compression • They are the areas involved with the most weight bearing CES – urinary retention • The urinary bladder (detrusor, internal sphincter, etc) is controlled by both sympathetic and parasympathetic innervation o Detrusor muscle [voluntary control] – contracts the bladder to allow urine to empty into the urethra (providing internal urinary sphincter is relaxed) o Internal urinary sphincter [involuntary control] – contracts to stop you from urinating • The ANS (autonomic nerve system) is split into sympathetic and parasympathetic: o Parasympathetic nervous system – craniosacral outflow o Sympathetic nervous system – thoracolumbar outflow L1-L3 (Sympathetic) nerves STOP you peeing. S2-S4 (Parasympathetic) nerves make you PEE.• In CES, nerve compression is commonly at L4/L5, and L5/S1 levels • Any nerve roots BELOW the site of compression are affected • In CES, the L1-L3 region will not be affected as it is ABOVE the site of compression o L1-L3 region is under sympathetic control, therefore the patient can hold in urine • However, the S2-S4 regions (under parasympathetic control) will be affected, making it difficult to urinate • This results in painless urinary retentionCES – red flags For all symptoms, establish when it started (months/ seasons are helpful if patient is unsure), and if the symptoms stayed the same or got better/ worse. • Bilateral sciatica (pain that radiates below BOTH knees) • Severe or progressive bilateral neurological deficit of the legs (i.e. major motor weakness with knee extension, ankle eversion, or foot dorsiflexion) • Difficulty initiating micturition or impaired sensation of urinary flow (aka urinary retention with overflow urinary incontinence) • Loss of sensation of rectal fullness (aka faecal incontinence) • Perianal, perineal or genital sensory loss (saddle anaesthesia or paraesthesia) • Laxity of the anal sphincter (consider assessing anal tone – not required in GP) • Erectile dysfunction CES – early warning signs • Loss of feeling/ pins and needles between inner thighs or genitals • Numbness in or around your back passage or buttocks • Altered feeling when using toilet paper to wipe yourself • Increasing difficulty when you try to urinate • Increasing difficulty when you try to stop or control your flow of urine • Loss of sensation when you pass urine • Leaking urine or recent need to use pads • Not knowing when your bladder is either full or empty • Inability to stop a bowel movement or leaking • Loss of sensation when you pass a bowel motion • Change in ability to achieve an erection or ejaculate • Loss of sensation in genitals during sexual intercourse Part 3 CES is a medical emergency. A REFERRAL needs to be made in time to allow surgical treatment (e.g. surgical decompression) before the syndrome is complete. This is essential to give the patient a chance of salvaging useful function. Cauda Equina Syndrome • Occurs when a patient suffers compression to the spinal nerve roots inside the dura, beyond the termination of the spinal cord • Most common cause – prolapsed intervertebral disc • Rare causes – infection or tumour • Failure to provide timely treatment results in dire consequences (e.g. paralysis, incontinence, impaired mobility) • BUT lower back pain is a common symptom, and CES is difficult to diagnose early CES (legal) claims Criteria for a successful claim: • The care provided by the doctor fell below a reasonable standard • ‘Breach of duty’ • Breach has caused loss or damage – termed ‘causation’ • Both claimants and defendants will instruct independent experts to investigate these two aspects of a claim Value of CES claims • CES claims can be made for a large sum of money • The degree of damage that resulted from the breach of duty will often only be a fraction of the claim, with the care costs and consequential losses forming the bulk of the overall value of the caseStatistics on claims • From Jan 2005 to Aug 2016: 150 claims to MDU, 92% of these against GPs • MDU defended 70% of claims successfully, spending 350,000 GBP • Of the cases that were settled, over £8 million in compensation was paid out by the MDU. Damages payments ranged from £2,250 to £670,000, and of the cases settled, 12% attracted damages payments of over £500,000 • 10% of claims related to out-of-hours consultation or telephone call o Difficult to assess CES over the phone/ out of hours MDU top tips • Conduct a full examination to establish the likely cause of the back pain and record this when finished • Consider any red flags o If red flags are present, the patient needs to be seen in hospital urgently § Call the orthopaedic or neurosurgical specialist for immediate advice, or if this is not available, arrange for ED admission o If no red flags, make a record in the notes to demonstrate you have actively considered the condition • If, after the assessment, the patient is being managed as having simple mechanical back pain: o Give appropriate safety netting advice – advise the patient of the red flag symptoms and the importance of seeking urgent medical attention if red flags are present o Make a record in the notes of the specific safety netting advice givenDocumentation of notes • Documents you make (including clinical records) to formally record your work must be clear, accurate and legible o You should make records at the same time as the events you are recording or as soon as possible afterwards • You must keep records that contain personal information about patients, colleagues or others securely, and in line with any data protection law requirements • Clinical records should include: o Relevant clinical findings o Decisions made and actions agreed, and who is making the decisions and agreeing the actions o The information given to patients o Any drugs prescribed or other investigation or treatment o Who is making the record and when Single Best Answer Questions 1. At which vertebral level does the spinal cord terminate? A. L1-L2 B. L3-L4 C. S4-S5 D. S1-S2 E. L2-L3 2. How is the process of micturition regulated by the autonomic nervous system? A. Sympathetic control – Urethral sphincter contracts, detrusor muscle relaxes B. Sympathetic control – Urethral sphincter relaxes, detrusor muscle contracts C. Parasympathetic control – Urethral sphincter contracts, detrusor muscle relaxes D. Parasympathetic control – Urethral sphincter contracts, detrusor muscle contracts E. Parasympathetic control – Urethral sphincter relaxes, detrusor muscle contracts 3. Lesion to which tract(s) can cause loss of pain and temperature on the contralateral side of the lesion? A. Anterior corticospinal tract B. Lateral corticospinal tract C. Spinothalamic tract D. Dorsal column E. Extrapyramidal tracts4. You experience a dull pain in your right hand. Which pathway would this pain signal follow? A. Green line B. Red line C. Yellow line D. Blue line E. Orange line 4. Which of the following patients does not have red flag symptoms of CES? A. 68 year old male with lower back pain and problems initiating micturition B. 50 year old female with lower back pain and loss of sensation during bowel movements C. 28 year old female with lower back pain and unilateral pain down right knee D. 49 year old male with lower back pain with erectile dysfunction E. 72 yar old male with lower back pain and bilateral numbness in thighs Answers 1. A - The Conus Medullaris is the bundled, tapered end of the spinal cord nerves and is the actual termination site of the spinal cord located at L1-L2. 2. E – Urination is a parasympathetic process (think rest and digest), 3. C – A lesion in the anterior and lateral corticospinal tract would cause paralysis on the ipsilateral side. Meanwhile, a lesion in the dorsal columns would cause loss of proprioception, fine touch and vibration on the ipsilateral side. Finally, a lesion in the extrapyramidal tracts would primarily cause alterations of the involuntary movements such as tremors, and spasms, impairment of voluntary movements as well as a decline in cognitive functions involving mainly memory tasks. 4. D – The pain is on the right hand, therefore is from the contralateral side, the left somatosensory cortex. Pain travels along the spinothalamic tract, and therefore must cross the dorsal horn. Dull pain is carried by C fibres, and hence crosses the reticular formation. 5. C – Red flag symptom of CES is bilateral sciatica, not unilateral.