Low Back Pain

1. Low Back Pain Anca Popescu, MD

2. Trivia • Low Back Pain affects at least 80% of the general population at some point in time • 90% of back pain sufferers recover completely within 6 weeks • For the 10% of patients who do not recover within a few weeks, back pain can be a painful, prolonged, costly and frustrating experience • Most abnormalities seen on MRI scans are painless • Physical and psychological factors contribute to a person’s experience of back pain

3. Sources of Back Pain • Muscles • Ligaments • Tendons • Bones • Facet joints • Discs (the outer rim of the disc, the annulus, can be a source of significant back pain due to its rich nerve supply and tendency towards injury)

4. The Intervertebral Disc • Jelly doughnut acting as shock absorber • Two parts: tough outer core (annulus fibrosus) and soft inner core (nucleus pulposus) • At birth, 80% of the disc is water • Aging  disc dehydration  micromotion instability  inflammatory proteins of nucleus pulposus leak out of the disc space  inflammation of structures next to the disc (e.g. nerve roots)  pain

6. The Facet Joints • Paired joints • Have cartilage on each surface and a capsule around them. Cartilage can degenerate as one ages  degenerative arthritis • The three-joint complex (2 facets and the disc) at each vertebral segment allows for motion in flexion, extension, rotation, and lateral bending (motion segment)

7. The Nerve Roots • In the cervical spine, the nerve root is named for the lower segment that it runs between (e.g. C6 at C5-C6 segment) • In the lumbar spine, the nerve is named for the upper segment that it runs between (e.g. L4 at L4-L5 segment) • The nerve passing to the next level runs over a weak spot in the disc space  discs tend to herniate (extrude) right under the nerve root  leg pain or arm pain (radiculopathy)

8. The Nerve Roots (cont’d) • A herniated disc may cause only leg pain and not low back pain  may initially be thought to be a problem with the leg/arm. • Leg pain from a lumbar disc herniation will usually run below the knee + to the foot, and may be accompanied by numbness

9. Anterior Longitudinal Ligament • Anterior to the vertebral bodies and discs, resists extension • Rupture by hyerextension injuries (esp cervical)

10. Posterior Longitudinal Ligament • Post aspect of vertebral bodies/ discs • Forms anteromedial wall of spinal canal • Hourglass shape in thoracolumbar, narrow over bodies & flaring at disks • Disrupted in hyperflexion injuries

11. Ligamentum Flavum • Bridges intervals between laminae • Laterally-blends with ant capsule of facet joints • Resists spinal flexion • Buckles with disk dessication  could lead to central cord contusion/syndrome

12. The Vertebrae

13. 50% of flexion occurs at the hips, and 50% occurs at the lumbar spine • Motion is divided between the 5 lumbar motion segments, although a disproportionate amount of the motion is at L4-L5 and L3-L4 • Consequently, these two segments are the most likely to break down with degeneration  may become unstable  excess of motion  pain

14. During embryological development there is a great deal of overlap of nerve supply to all of these structures • Therefore, it impossible for the brain to distinguish between injury to one structure versus another  a torn or herniated disc can feel identical to a bruised muscle or ligament injury

15. Muscles that Support the Spine • Extensors (back muscles: erector spinae, cervical, thoracic and lumbar paravertebrals and gluteals) • Flexors (abdominal muscles and iliopsoas) • Obliques / rotators (side muscles)

17. Role of Exercise • Regular exercise stretches back muscles  increase resistance to strain, tear or spasm  less likely to develop back pain from muscle strain • A complete exercise program consists of a combination of stretching, strengthening, and aerobic conditioning • Most muscles do not get adequate exercise from daily activities and tend to weaken with age

19. Muscle Strain • Most common cause of acute low back pain • Causes: lifting heavy objects, sudden movements or falls • Pathogenesis: muscle strain  inflammation  spasm  severe pain  difficulty moving  deconditioning • Prognosis: good (spontaneous healing due good muscle blood supply) • Time course: several hours  few weeks • Pain > 2 weeks  muscle weakness and wasting (disuse atrophy)  muscles are less able to help hold up the spine  more pain

20. Axial Low Back Pain • Description: sharp or dull, constant or intermittent, mild or severe, worse with certain activities and position changes and relieved by rest • Exact diagnosis as to which structure is causing the pain is rarely possible and has little significance to treatment • The presence of a herniated, degenerative disc or bulging disc on MRI may have nothing to do with the pain episode

22. Treatment of Axial Back Pain • Rest • Physical therapy • Medications • Recovery: within 6 weeks (in 90% of cases) • If pain persists > 6 -8 weeks, additional testing and/or injections may be useful in diagnosing and treating the source of pain. • Surgery is rarely recommended (unpredictable effect)

23. Radicular Pain • Description:deep, steady, reproducible with certain activities (eg, sitting or walking) + numbness and tingling, muscle weakness and loss of specific reflexes • Distribution: the affected extremity along the course of a spinal nerve root • Etiology: - Herniated disc with nerve compression - Foraminal stenosis from osteoarthritis / osteophytes - Diabetes - Nerve root injuries - Scarring from previous spinal surgery • Pathogenesis: compression, inflammation and/or injury to a spinal nerve root

24. Lumbar Radiculopathy • L5 runs over the top of the foot and for S1 it runs on the outside of the foot • L5 radiculopathy: weakness of foot dorsiflexion and big toe extension  inability to heel walk • S1 radiculopathy: gastrocnemius weakness  inability to toe walk and loss of ankle jerk

26. Sciatica • Distribution: low back  buttock  back of the leg  + foot / toes • Description: burning/ tingling/ shooting pain down the leg, worse with sitting and standing up • Associated symptoms: weakness, numbness or difficulty moving the leg or foot • Pathogenesis: - herniated disc - lumbar spinal stenosis - degenerative disc disease - spondylolisthesis • Prognosis: good (improvement in two weeks to a few months)

28. Treatment of Sciatica • Physical therapy, osteopathic/ chiropractic procedures (relieve the pressure) • Medical (NSAID’s, oral steroids, epidural steroid injections) for inflammation. • Surgery (microdiscectomy/ laminectomy) relieves both pressure and inflammation

29. Physical Therapy • Strengthening • General stretching • McKenzie method of passive end-range stretching • Conventional physical therapy • hot packs • massage and stretching • flexibility • coordination exercises

30. An Australian study indicated that a television campaign advising people with back pain to stay active and keep working reduced work-injury claims and medical expenses Buchbinder R, Jolley D. Population based intervention to change back pain beliefs: three year follow up population survey BMJ 2004;328:321

31. Muscle Relaxants • Tizanidine (centrally acting alpha2 agonist): analgesia, sedation, myorelaxant • Cyclobenzaprine: ? Central effects (brainstem) used for short term only. Side effects: dizziness, drowsiness, dry mouth. Likelihood of pain relief at 14 days is 5 times higher than with placebo; highest efficacy early (first week) Browning R, Jackson JL, O’Malley PG. Cyclobenzaprine and back pain: a metaanalysis. JAMA 2001; 161:1613-20 • Carisoprodol and methocarbamol (central action). Side effects: drowsiness, tremor, tachycardia, orthostasis • Benzodiazepines (diazepam): increase GABA release (inhibitory)

32. Analgesics • Tramadol: central effects mediated via mu receptors (affinity 6000 times less than the opioids) • Opioids: analgesia at different levels of CNS (spinal cord, basal ganglia, limbic system): morphine, codeine, hydrocodone, oxycodone, fentanyl, hydromorphone, methadone

33. NSAIDs • Central and peripheral mechanisms (reduction of cyclooxygenase and leukotrienes which sensitize nerve fiber endings to bradykinins and leukotrienes) • Efficacy of analgesia is not proportional to a given NSAID antiinflammatory potency. McCormack K, Brune K. Dissociation between the antinociceptive and antiinflammatory effects of the nin-steroidal antiiflammatory drugs: a survey of their analgesic effects. Drugs 1991; 41: 533-47 • NSAIDs have roughly equivalent analgesic efficacy Gotzsche PC. Non-steroidal antiinflammatory drugs. Br Med J 2000; 320:1058-61

34. Anticonvulsants • Decrease pain by decreasing membrane excitability of neurons (raise depolarization potential threshold) • No well designed, prospective, randomized controlled studies in radiculopathy • Gabapentin, pregabalin, lamotrigine, topiramate (newer anticonvulsants) better tolerated than the old ones. Gabapentin enhances the the acute analgesic effect of morphine when administered concomitantly Eckhardt K, Ammon S, Hoffman U et al. Gabapentin enhances the analgesic effect of morphine in healthy volunteers. Reg Anesth Pain Med 2000; 91: 185-91

35. Antidepressants • Tricyclic and tetracyclic drugs: small but consistent benefits in pain reduction in randomized trials in patients with chronic low back pain, without clinical depression (a 20 -40 % greater reduction in pain than with placebo, during 4-8 weeks) Staiger TO, Gaster B, Sullivan MD, Deyo RA. Systematic review of antidepressants in the treatment of chronic low back pain. Spine 2003;28:2540-5 • nortriptyline (25 to 100 mg) • amitriptyline (50 to 150 mg) • maprotiline (50 to 150 mg)

36. Trigger Point Injections • Taut bands of muscle, foci of irritability • When compressed cause referred pain and tenderness (nociceptorscentral and peripheral sensitization). • May be active or latent • Commonly in the multifidus, longissimus, iliocostalis, quadratus lumborum • Injection technique: thin gauge needle inserted rapidly through the skin  twitch response • Injections can be performed with saline, ketorolac, steroids, or dry needling technique

37. When to Operate? • Severe pain that is refractory to manual and medical treatments • If there is significant muscle weakness. • Radicular pain/leg pain gets relieved in 85% to 90% of patients. • Relief of low back pain is much less predictable. • If nerve compression cannot be documented on an MRI or CT myelogram, surgery is unlikely to be successful

38. Spinal Fusion Surgery • Possible efficacy in patients with isolated one- or two-level spondylosis and few or no coexisting factors for chronic pain (e.g., disputed compensation issues, psychological distress, or other types of chronic pain) • No better results in patients with multiple coexisting factors than aggressive nonoperative management Ivar Brox J, Sorensen R, Friis A, et al. Randomized clinical trial of lumbar instrumented fusion and cognitive intervention and exercises in patients with chronic low back pain and disc degeneration. Spine 2003;28:1913-21

39. Types of Lower Back Pain that Indicate a Surgical Emergency • Sudden bowel and/or bladder incontinence (cauda equina syndrome) • Progressive weakness in the legs (cauda equina syndrome) • Severe, continuous abdominal and back pain (e.g. abdominal aortic aneurysm)

40. Cauda Equina Syndrome

41. Patients Requiring an Immediate Evaluation (Worrisome Symptoms) • Fever and chills • History of cancer with recent weight loss • Severe trauma • Significant leg weakness • Pain worse at night (especially if it wakes up from deep sleep)

42. Causes of Low Back Pain for Young Adults (< 60) • Disc herniation buttock/ leg pain radiating down to the foot, worse after a long period of standing or sitting + numbness down the leg • Degenerative disc disease “mechanical” low back pain (pain caused by movement: bending forward, running). May result from a twisting injury that weakens the disc • Stress fracture or spondylolisthesis stress on the disc  low back pain + leg pain worse when standing or walking

45. Low Back Pain for Older Adults (>60) • Facet joint osteoarthritis (degenerative arthritis) low back pain that is worse in the morning and in the evening + stiffness. Caused by a loss of the cartilage between the facet joints in the back • Lumbar spinal stenosis or degenerative spondylolisthesis pain down the legs when walking and standing upright. Caused by pressure on the nerves at the point where they exit the spine

47. Terminology used in Back Pain • Spondylosis: arthritis of the spine • Spondylolisthesis: anterior displacement of a vertebra on the one beneath it • Spondylolysis: a fracture in the pars interarticularis where the vertebral body and the posterior elements, protecting the nerves are joined • Spinal stenosis: local, segmental, or generalized narrowing of the central spinal canal • Radiculopathy: impairment of a nerve root • Sciatica: pain, numbness, tingling in the distribution of the sciatic nerve • Cauda equina syndrome: loss of bowel and bladder control and numbness in the groin and saddle area of the perineum, associated with weakness of the lower extremities • Lordosis, kyphosis, scoliosis • Piriformis syndrome: thought to be a condition in which the piriformis muscle compresses or irritates the sciatic nerve

48. Differential Diagnosis of Low Back Pain • Mechanical low back or leg pain (97%) • Lumbar strain, sprain (70%) • Degenerative processes of disks and facets, usually age-related (10%) • Herniated disk (4%) • Spinal stenosis (3%) • Osteoporotic compression fracture (4%) • Spondylolisthesis (2%) • Traumatic fracture (<1%) • Congenital disease (<1%) • Severe kyphosis, Severe scoliosis, Transitional vertebrae Spondylolysis, Internal disk disruption or diskogenic low back pain

49. Differential Diagnosis of Low Back Pain • Visceral disease (2%) • Disease of pelvic organs (Prostatitis, Endometriosis, Chronic pelvic inflammatory disease) • Renal disease (Nephrolithiasis, Pyelonephritis, Perinephric abscess) • Aortic aneurysm • Gastrointestinal disease (Pancreatitis, Cholecystitis, Penetrating ulcer)

50. Differential Diagnosis of Low Back Pain • Non-mechanical spinal conditions (1%) • Neoplasia (Multiple myeloma, Metastatic carcinoma, Lymphoma and leukemia, Spinal cord tumors, Retroperitoneal tumors, Primary vertebral tumors) • Infection (Osteomyelitis, Septic diskitis, Paraspinous abscess, Epidural abscess, Shingles) • Inflammatory arthritis (Ankylosing spondylitis, Psoriatic spondylitis, Reiter's syndrome Inflammatory bowel disease) • Scheuermann's disease (osteochondrosis) • Paget's disease of bone