The Lumbar Spine Flashcards
(233 cards)
Describe the impact of low back pain historically and currently.
most common cause of disability and lost work time (other than common cold) in industrialized countries; most common reason to seek physical therapy; overall economic/societal burden has not improved over the last few years, and may actually be worsening
Define prevalence
the amount of people with a condition at any given time
Describe the prevalence of low back pain worldwide.
difficult to estimate acute pain, because it tends to change very rapidly and can have varying definitions; chronic low back pain is likely between 10-30% on any given day.
What percentage of people with low back pain for less than 3 months will recover? How long does this generally take?
80% of people with acute low back pain (<3 mo) will recover within 6-8 weeks
Describe an inception cohort study design.
enroll patients at the time of onset of symptoms and follow them over time
What percentage of people with acute low back pain will return to work within 2 weeks, according to Henschke et al? Within 3 months?
50% will return to work within 2 weeks; 83% within 3 months
What percentage of people with low back pain symptoms will report continued symptoms after 12 months, according to Henschke et al?
23%
Why is it important to advise patients on the nature of acute low back pain and its prognosis?
LBP is probably not an isolated episode, but a condition characterized by flare-ups of symptoms. Patients should be informed that recovery is likely in a short time frame, but recurrences are likely and normal; Flare-ups do not necessarily represent a failure of treatment
What is the prognosis of chronic low back pain?
Highly variable; “refractory to intervention”; though studies show that even patient with low back pain for more than 3 months can recover fully (1/3 of participants reported that they were pain-free and fully functionally recovered within 1 year), so there is always hope
What study design would we need to use in order to determine exactly the factors that cause the development / influence the course of low back pain? What are the ethical issues that this would raise?
Prospective, randomized study design. We’d have to assign a person to perform activities that we believe to be harmful.
What kinds of study designs are ethical for exploring activities that might cause low back pain?
Non-experimental studies such as case-series designs or cohort designs that follow people over time and compare various traits to the outcome
Describe the findings from Bakker, et al on the relationship between specific activities and low back pain recovery.
Bakker et al found no relationship between work-related spinal loading, prolonged sitting, and/or participation in sports activities on the recovery from low back pain
What is the clinical takeaway from the currently literature on activities that cause / contribute to low back pain rehab?
In conflict with previous beliefs, lifting, prolonged sitting, and sports activities are not likely to be harmful to the spine and should not necessarily be limited in those without a clear rationale
Describe the low back pain clinical prediction rule derived by Hancock et al. and their statistical findings
Acute LBP; lower than average initial pain, shorter duration of symptoms, fewer previous episodes = recover more quickly; Hazard Ratio 3.5
What is a hazard ratio?
A measure of how often a particular event happens in one group compared to how often it happens in another group, over time (Hazard Ratio of 1 = no increased risk in the test group, 2 = twice the risk, etc.)
What is a confidence interval?
Probability measurement. A confidence interval is how much certainty/uncertainty there is with any particular statistic. (They can take any number of probability limits, with the most common being a 95% or 99% confidence level.)
Describe the utility of using the current low back pain CPR to predict prognosis of acute LBP
basic guideline, but there are probably more factors than were originally taken into account when the CPR was derived. (Weak-moderate evidence in addition to lack of validation studies)
How long can the average acute low back pain episode last, according to Adam Meakins?
can last up to 6 weeks
What are the 3 primary anatomic regions of the nervous system in which pain modulation occurs
- spinal cord
- brain stem (periaqueductal gray, rostral ventral medulla)
- higher brain centers (anterior cingulate cortex, amygdala, somatosensory cortex)
What is pain modulation?
the way in which nociceptive (danger) signals are amplified or dampened within the nervous system via biochemical activity
Describe pain dampening events at the spinal cord.
non-nociceptive a-beta nerve fibers recruit inhibitory neurons in the substantia gelatinosa of the posterior spinal cord, which chemically blocks nociceptive a-delta and c-fibers before they can send a signal up the spinal cord to the brain
What is a nerve fiber?
axon or dendrite of a single neuron
Describe spinal sensitization (secondary hyperalgesia).
pain is increased (switched on) because dorsal horn neurons have increased excitability and spontaneously discharge ascending nociceptive information; the excitability is due to repeated firing of “pain-sensitive” c-fibers from somatic tissues (like muscles and joints); the excitability is also enhanced by the transcription of rapidly-expressed genes that increase the sensitization of nociceptors; this means that the threshold is lower and the “receptor field” is wider
Describe pain dampening events at the level of the brain stem.
diffuse inhibition of pain (switch off) happens when the periaqueductal gray (PAG) matter and/or rostral ventral medulla (RVM) are stimulated by pathways that descend from high brain centers; PAG system uses endogenous opioids and descends to the dorsal horn