Disorders of the lumbar spine Flashcards
What characterises mechanical back pain?
It is characterised by pain when the spine is loaded,
that worsens with exercise and is relieved by rest. It tends to be intermittent and is often triggered by innocuous activity.
What are the risk factors for mechanical back pain?
Risk factors include obesity, poor
posture, a sedentary lifestyle with deconditioning of the paraspinal (core) muscles, poorly-designed seating and incorrect manual handling (bending and
lifting) techniques.
Describe the degenerative changes in the vertebral column: disc degeneration and marginal
osteophytosis
The nucleus pulposus of the intervertebral discs dehydrates with age. This leads to a decrease in the height of the discs, bulging of the discs and alteration of the load stresses on the joints. Osteophytes (bony spurs) called syndesmophytes
therefore develop adjacent to the end plates of the discs. This is known as marginal osteophytosis. Increased stress is also placed on the facet joints, which also develop osteoarthritic changes. The facet joints are innervated by the meningeal branch of the spinal nerve, so arthritis in these joints is perceived as painful.
As the disc height decreases and arthritis develops in the facet joints and vertebral bodies, the intervertebral foramina decrease in size. This can lead to compression of the spinal nerves and is perceived as radicular or nerve pain.
What are the four stages of disk herniation?
Disc degeneration: chemical changes associated with ageing cause discs to dehydrate and bulge
2. Prolapse: Protrusion of the nucleus pulposus occurs with slight impingement into the spinal canal. The nucleus pulposus is contained within a rim of annulus fibrosus
3. Extrusion: The nucleus pulposus breaks through the annulus fibrosus but is still contained within the disc space
4. Sequestration: The nucleus pulposus separates from the main body of the disc and enters the spinal canal.
What is paracentral prolapse and which nerve root is it more likely to affect?
The nucleus pulposus most commonly herniates posterolaterally (lateral to the posterior longitudinal ligament), causing compression of a spinal nerve
root within the intervertebral foramen. This is known as a paracentral prolapse and occurs in 96% of cases. The nerve root that emerges at the level below is termed the traversing nerve root.
What is far lateral prolapse and which nerve root is it more likely to affect?
The nerve root that emerges from the spinal canal at the same level as the intervertebral disc is termed the exiting nerve root. This is most at risk in a ‘far lateral’ disc herniation
What is sciatica?
Pain caused by irritation or compression of one or
more of the nerve roots that contribute to the sciatic nerve (i.e. L4, L5, S1, S2 and S3)
Where is pain typically experienced in sciatica?
The pain experienced is typically experienced in the back and buttock and radiates to the dermatome supplied by the affected nerve root. Hence it
follows a path ‘from the back to the dermatome’.
What is the typical distribution of pain in sciatica?
Typical distribution of pain:
L4 sciatica: anterior thigh, anterior knee, medial leg
L5 sciatica: lateral thigh, lateral leg, dorsum of foot
S1 sciatica: posterior thigh, posterior leg, heel, sole of foot
Where will the patient experience paraesthesia in sciatica?
If the nerve compression also causes paraesthesia, this will be only experienced in the affected dermatome (rather than the full path from lumbar spine to dermatome).
What is cauda equina syndrome?
Cauda equina syndrome can develop in the context of prolapsed intervertebral disc when there is a ‘canal filling disc’ that compresses the lumbar and sacral nerve roots within the spinal canal.
What are the causes of cauda equina syndrome?
- Disc prolapse
- Tumours (primary or secondary) affecting the vertebral column or meninges
- Spinal infection/abcess
- Spinal stenosis secondary to arthritis
- Vertebral fracture
- Spinal haemorrhage
- Late-stage ankylosis spondylitis
What are the red flag symptoms of cauda equina syndrome?
• Bilateral sciatica
• Perianal numbness (saddle anaesthesia)
• Painless retention of urine
• Urinary / faecal incontinence
• Erectile dysfunction
How is cauda equina syndrome treated?
Cauda equina syndrome needs to be treated by surgical decompression within 48 hours of the onset of sphincter symptoms, otherwise the prognosis is poor.
What are the consequences of missing a cauda equina syndrome diagnosis?
The consequences of missing this diagnosis are serious and life-changing e.g. chronic
neuropathic pain, impotence, having to perform intermittent self-catheterisation to pass urine, faecal incontinence or impaction requiring manual evacuation of faeces, loss of sensation and lower limb weakness requiring a wheelchair. You do
not want to miss a case of cauda equina syndrome!
What is spinal canal stenosis?
Spinal canal stenosis is an abnormal narrowing
of the spinal canal that compresses either the
spinal cord or the nerve roots.
What are the main causes of spinal canal stenosis?
• Disc bulging
• Facet joint osteoarthritis
• Ligamentum flavum hypertrophy
What are other causes of spinal canal stenosis?
• Compression fractures of the vertebral bodies
• Spondylolisthesis (see below)
• Trauma
What are the symptoms of spinal canal stenosis?
The symptoms depend on the region of the cord or nerve roots that are affected. Lumbar stenosis is most common, followed by cervical stenosis.
Symptoms include:
• Discomfort whilst standing (95% of patients)
• Discomfort or pain in the shoulder, arm or hand (for cervical stenosis) or in the lower limb (for lumbar stenosis)
• Bilateral symptoms in approximately 70% of patients
• Numbness at or below the level of the stenosis
• Weakness at or below the level of the stenosis
• Neurogenic claudication (see below)
What is neurogenic claudication?
Neurogenic claudication (or pseudoclaudication) is a symptom rather than a diagnosis. The patient reports pain and/or pins and needles in the legs on prolonged standing and on walking, radiating in a sciatica distribution.
Neurogenic means that the problem originates in the nerve and
claudication is derived from the Latin for limp (claudigo), as the patient feels a cramping pain or weakness in their legs, and therefore tends to limp.
How does neurogenic claudication occur?
It results from compression of the spinal nerves as they emerge from the lumbosacral spinal cord (see spinal canal stenosis above). This leads to venous engorgement of the nerve roots during exercise, leading to reduced arterial inflow and transient arterial ischaemia. The ischaemia of the affected nerve(s) results in the pain and/or paraesthesia.
How is neurogenic claudication relieved?
It is classically
relieved by rest (most effective), a change in position and by flexion of the spine. Movements that involve flexion of the waist are well tolerated such as cycling, pushing a trolley and climbing stairs.
What is spondylolisthesis?
Spondylolisthesis is anterior displacement of the vertebra above relative to the vertebra below
What is spondylosis?
A complete fracture in this location without displacement is referred to as spondylolysis
