Chapter 49- Low back pain and sciatica Flashcards
What are risk factors for low back pain?
repetitive heavy lifting, static working posture (sitting/standing), frequent twisting or bending, vibration, ciagarette smoking
What are potential sources of pain in the spine?
Anterior compartment- vertebral body, discs
Middle compartment- Posterior longitudinal ligament (becomes more narrow in lumbar region–weaker); epidural space, meninges, spinal cord, nerve roots, dorsal root ganglia, ligamentum flavum (connects laminae of adjacent vertebrae)
Posterior compartment- facet joints, laminae, spinous processes
What is the sinovertebral nerve and what does it innerviate?
originates lateral to the neural foramina and is a branch of the somatic ventral nerve root.
AKA nerve of Luschka
Innervates the outer annulus of the disc, PLL, epidural membranes and dural
How does natural wear and tear of the discs cause pain?
Microtrauma induced by natural wear and tear causes release of neuromodulators like prostaglandins, substance P that produce inflammatino of the nerve roots and meninges and sensitize local nociceptors.
Other theory is that since the material within the nucleus pulposis is sheltered from the immune system it acts as a foreign protein and may cause autoimmune reaction. This may lead to high nociceptive input into spinal cord and central sensitization.
What is central sensitization?
increase in spontaneous discharge and an expansion of the neural receptive fields of wide-dynamic-range (WDR) neurons. WDR neurons typically have both pain stimuli input and nonpainful stimuli input. (1st order neurons can synapse on 2nd order or WDR)
What is the anatomy of the intervertebral disc
Centrally located well-hydrated proteoglycan matrix (nucleus pulposus) that takes up 2/3 of the disc.
Surrounding this is a fibrocartilagnous ring made up of type 1 collagen (annulus fibrosis). The annulus is stronger anteriorly and weaker posteriorly.
What happens to discs as they age?
Number of viable cells decrease and water content decreases–less compliant.
Where will a disc tend to herniate?
Posteriolaterally- hits nerve roots.
How is the disc innerviated?
In healthy back- only outer third of the annulus fibrosus is innervated. But if the disc is disrupted, small unmyelinated nerve fiers grown into the inner parts of the disc.
How can discs cause radiculopathy?
Compression injury, chemical irritation and inflammation, immune rection and edema formation.
What is the anatomy of the spinal facets?
2 arthrodial joints superiorly and inferiorly lined with synovium, lubricated by synovial fluid within a joint capsule.
What is the anatomy of the spinal facets?
2 arthrodial joints superiorly and inferiorly lined with synovium, lubricated by synovial fluid within a joint capsule. Remember that the most cephalad bone is actually the inferior portion of the vertebral articular process and the caudad portion of the superior articular process of the lower vertebral segment.
How can facets causes pain?
becomes degenerative over time
can develop hypertrophic facet joints or cysts that encroach on the interverteral foramina and can contribute to central spinal or forminal stenosis.
Patients with disc problems have exacerbation of the pain with this.
spinal flexion- increases intradisc pressure
Patients with spinal stenosis have exacerbation of the pain with this movement.
extension causes radicular pain– spinal flexion releaves pain
