8. clinical conditions of the lumbar spine

Question 1

What is mechanical back pain characterised by?

Answer 1

• pain when the spine is loaded,
• that worsens with exercise
• relieved by rest
• It tends to be intermittent
• often triggered by innocuous activity

Question 2

What are the risk factors for mechanical back pain?

Answer 2

Obesity, poor posture, a sedentary lifestyle with deconditioning of the paraspinal (core) muscles, poorly-designed seating and incorrect manual handling (bending and lifting) techniques.

Question 3

What is the epidemiology of mechanical back pain in the UK?

Answer 3

• 50% of the UK population report lumbar back pain for at least 24 hours in any one year; half of those episodes last > 4 weeks.
• 80% of the UK population will experience lumbar back pain lasting >24 hours in their lifetime.

Question 4

What is marginal osteophytosis?

Answer 4

Development of osteophytes (bony spurs) called syndesmophytes adjacent to the end plates of the discs.

Question 5

Why does marginal osteophytosis occur?

Answer 5

dehydration of nucleus pulposus of the intervertebral discs with age leads to:

• decrease in the height of the discs
• bulging of the discs
• alteration of the load stresses on the joints

Question 6

What occurs due to increase stress on the facet joints?

Answer 6

Develop osteoarthritic changes.

Facet joints are innervated by the meningeal branch of the spinal nerve, so arthritis in these joints is perceived as painful.

Question 7

What can development of arthritis in verterbral bodies and facet joints and reduced disc height lead to?

Answer 7

Reduction in the size of the intervertebral foramen, leading to compression of the spinal nerves and is perceived as radicular or nerve pain.

Question 8

How does a herniated disc cause pain?

Answer 8

Pain occurs due to herniated disc material pressing on a spinal nerve

Question 9

Which age group do herniated discs occur most commonly in and how long do they take to resolve?

Answer 9

• most common age group is 30-50 years

- 90% of cases resolve by 3 months

Question 10

What are the 4 stages of disc herniation?

Answer 10

1. 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.

Question 11

What are the most common sites for a slipped disc?

Answer 11

The L4/5 and L5/S1 discs due to the mechanical loading at these joints.

Question 12

At what sites are nerve roots most vulnerable in a disc slippage?

Answer 12

1) Where they cross the intervertebral disc (paracentrally);

2) Where they exit the spinal canal in the neural foramen (laterally).

Question 13

What are the different types of disc herniation?

Answer 13

• Paracentral prolapse (96% of cases)
• far lateral (2%)
• central (2%)

Question 14

Describe paracentral prolapse

Answer 14

The nucleus pulposus most commonly herniates posterolaterally (lateral to the posterior longitudinal ligament), causing compression of a spinal nerve
root within the intervertebral foramen

Question 15

What is the exiting nerve root and which type of disc herniation puts it at the most risk?

Answer 15

Spinal nerve exiting at the level of the disc herniation

- far lateral herniation

Question 16

What is the tranversing nerve root and which type of disc herniation puts it at the most risk?

Answer 16

Nerve root that emerges at the level below the herniated disc
- paracentral herniation

Question 17

What does Central herniation carry a risk of?

Answer 17

cauda equina syndrome

Question 18

In a paracentral herniation of the L4/5 disc, which root is most frequently compressed?

Answer 18

the L5 root (the traversing root) is most frequently compressed because the L4 root (the exiting root) emerges above the level of the L4/5 disc

Question 19

In a paracentral herniation of the L5/S1 disc, which root is most frequently compressed?

Answer 19

the S1 root, not the L5 root.

Question 20

What is sciatica?

Answer 20

Pain caused by irritation or compression of one or

more of the nerve roots that contribute to the sciatic nerve.

Question 21

Which nerve roots contribute to the sciatic nerve?

Answer 21

L4, L5, S1, S2 and S3

Question 22

What can cause sciatica?

Answer 22

Marginal osteophytosis, slipped disc, etc

Question 23

Where is the general experience of pain in sciatica?

Answer 23

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’.

Question 24

What are the typical distributions of pain in sciatica?

Answer 24

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

Question 25

If sciatica causes paraesthesia, where is it felt?

Answer 25

Only experienced in the affected dermatome (rather than the full path from lumbar spine to
dermatome).

Question 26

What is cauda equina syndrome?

Answer 26

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

Question 27

What causes cauda equina syndrome?

Answer 27

Approx. 5% of cases of cauda equina syndrome are due to a disc prolapse (most commonly aged 30 - 50 years)

Other causes include:

• tumours (primary or secondary) affecting the vertebral column or meninges
• spinal infection / abscess
• spinal stenosis secondary to arthritis
• vertebral fracture
• spinal haemorrhage
• late-stage ankylosing spondylitis

Question 28

What are the red flag symptoms of cauda equina?

Answer 28

• Bilateral sciatica
• Perianal numbness (saddle anaesthesia)
• Painless retention of urine
• Urinary / faecal incontinence
• Erectile dysfunction

Question 29

How is cauda equina treated and how quickly?

Answer 29

Needs to be treated by surgical decompression within 48 hours of the onset of sphincter symptoms, otherwise the prognosis is poor.

Question 30

What are the consequences of missing a diagnosis of cauda equina syndrome?

Answer 30

• chronic neuropathic pain
• impotence
• having to perform intermittent self catheterisation to pass urine
• faecal incontinence or impaction requiring manual evacuation of the rectum
• loss of sensation and lower limb weakness requiring a wheelchair.

Question 31

What is spinal canal stenosis?

Answer 31

Spinal canal stenosis is an abnormal narrowing of the spinal canal that compresses either the spinal cord or the nerve roots.

Question 32

Where does spinal canal stenosis occur most commonly and in which age group?

Answer 32

Spinal canal stenosis tends to affect the elderly. Lumbar stenosis is most common, followed by cervical stenosis

Question 33

What causes spinal canal stenosis?

Answer 33

Due to a combination of:

• Disc bulging
• Facet joint osteoarthritis
• Ligamentum flavum hypertrophy

Other causes include:

• Compression fractures of the vertebral bodies
• Spondylolisthesis
• Trauma

Question 34

What are the symptoms of spinal canal stenosis?

Answer 34

Depend on region affected

• 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

Question 35

What is the prognosis of lumbar canal stenosis?

Answer 35

The natural history of lumbar canal stenosis is that 70% of patients’ symptoms stay unchanged, 15% get progressively worse and 15% improve with time.

Question 36

What is neurogenic caludication?

Answer 36

Is a symptom rather than a diagnosis:
Patient reports pain and/or pins and needles in the legs on prolonged standing and on walking, radiating in a sciatica distribution.

• may be uni or bilateral

Question 37

What causes neurogenic claudication?

Answer 37

It results from compression of the spinal nerves as they emerge from the lumbosacral spinal cord. 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.

Question 38

How is neurogenic claudication relieved?

Answer 38

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.

Question 39

What does neurogenic claudication mean?

Answer 39

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

Question 40

What is Spondylolisthesis?

Answer 40

anterior displacement of the vertebra above on the vertebra below.

Question 41

What are the different classifications of Spondylolisthesis?

Answer 41

• Congenital or dysplastic: congenital instability of the facet joints
• Isthmic: A defect in the pars interarticularis
• Degenerative: results from facet joint arthritis and joint remodelling (age >50 years)
• Traumatic: Acute fractures in the neural arch, other than the pars interarticularis
• Pathological: Infection or malignancy
• Iatrogenic: Caused by surgical intervention e.g. if too much lamina and facet joint is excised during a laminectomy operation

Question 42

What are some symptoms of spondylolisthesis?

Answer 42

Some individuals remain asymptomatic
Most complain of some discomfort ranging from:
- occasional lower back pain
- incapacitating mechanical pain
- sciatica from nerve root compression
- neurogenic claudication

Question 43

What is pars interarticularis?

Answer 43

In the isthmic type, a defect (e.g. stress fracture) develops in the pars interarticularis, which is the part of the vertebra between the superior and inferior articular processes.

Question 44

What is the difference between spondylolysis and spondylolisthesis?

Answer 44

A complete fracture in this location without displacement is referred to as spondylolysis. Once anterior displacement of the upper vertebra occurs, this is spondylolisthesis.

Question 45

What is a lumbar puncture and why is it carried out?

Answer 45

Withdrawal of fluid from the subarachnoid space of the lumbar cistern.
It is an important diagnostic test for a variety of central nervous system disorders including meningitis, multiple sclerosis etc.

Question 46

How should the patient be positioned in a lumbar puncture and why?

Answer 46

Patient lying on the side with the back and hips flexed (knee-chest position).

Flexion of the vertebral column facilitates insertion of the needle by spreading apart the vertebral laminae and spinous processes, stretching the ligamenta flava.

Question 47

Where is the lumber puncture needle inserted and how can this area be located?

Answer 47

In the midline between L3-L4 (or L4-L5).

Located by finding the plane transecting the highest points of the iliac crests—the supracristal plane—this usually passes through the L4 spinous
process.

Question 48

Why is a lumbar puncture done at the C3/4 level?

Answer 48

At these levels, there is no danger of damaging the spinal cord.

Question 49

How deep does the lumbar puncture needle need to be inserted and what will it penetrate?

Answer 49

4-6 cm (more in obese)
The needle “pops” through the ligamentum flavum, then punctures the dura and arachnoid, and enters the lumbar cistern. When the stylet is removed, CSF escapes and can be collected.

Question 50

What is the lumbar cistern?

Answer 50

The lumbar cistern refers to the subarachnoid space in the lower lumbar spinal canal.