Prolapsed Disc

Question 1

What are the 3 components of the vertebral disc?

How many discs are there?

Answer 1

Each disc has 3 parts:

i. gelatinous inner portion = central nucleus puplosus
ii. tough outer ring = peripheral annulus fibrosis
iii. 2 vertebral end plates

There are 23 discs in the spine: 6 cervical, 12 thoracic and 5 lumbar

Question 2

What is the functions of

i. Nucleus pulposus
ii. Annulus Fibrosus
iii. Vertebral end-plates?

Answer 2

i. Nucleus pulposus : Gelatinous structure at the centre of the vertebral disc.

It gives spine strength and flexibility.

It is made from 80% water and type 2 collagen.

ii. Annulus fibrosis : lamellae or concentric layers of collagen fibres - aids in resistance to multidirectional movements.

Also contains innervation for the discs.

Only the outer annulus is vascularised

iii. Vertebral endplates : upper and lower cartilaginous endplates which allows diffusion of nutritions for the discs.

Question 3

What is the functions of the discs?

Answer 3

Stability

Resistance to axial, rotational and bending load

Cushioning for the vertebrae

Protection of nerves in the spine and between vertebrae

Question 4

What is a prolapsed disc?

Answer 4

Nucleus pulposus can protrude through the outer annulus due to an injury or weakness.

Herniated disc impinges compression of the spinal nerve associated with the inferior vertebrae i.e. L4/L5 herniation affects L5 nerve roots

Compression of spinal nerve = numbness and parasthesia

This can cause pain & discomfort.

Question 5

What is the most common level for slipped disc and why?

Answer 5

L5/S1 (lower back)=> due to thinning of the posterior longitudinal ligament toward its caudal end.

Question 6

What are the 3 subtypes of disc herniations?

Answer 6

1. Disc protrusion
2. Disc extrusion
   => annular fibrosus is damaged allowing nucleus pulposus to herniate
3. Disc sequestration
   => herniated material breaks off from the body of the nucleus pulposus

Question 7

What are the symptoms of a slipped disc?

Answer 7

=> pain & numbness (most commonly on one side of the body)

=> pain extending to your arms & legs

=> pain that worsens at night or with certain movement

=> pain that worsens on standing or sitting

=> pain when walking short distances

=> unexplained muscle weakness

=> paraesthesia, aching or burning sensation in the affected area

Question 8

What are the risk factors for slipped disc?

Answer 8

=> Age (cervical / lumbar degenerative changes)

=> Lifting heavy weights (occupation)

=> Twisting / turning motions

=> Overweight

=> Weak muscles + sedentary lifestyle

=> Genetics

=> Smoking

Question 9

Who does it affect?

Answer 9

Men > women

Question 10

What are the characteristics of lateral cervical disc protrusion?

Answer 10

=> Pain in arm

=> C7 protrusion is the most common

=> Root pain radiating to C7 myotome i.e. triceps, deep to scapula and extensor aspect of forearm)

=> Sensory disturbance i.e. tingling and numbness in C7 dermatome / loss of sensation in C7 dermatome

=> Weakness / wasting of triceps, wrist, finger extensors

=> Loss of tricep jerk (C7 reflex arc)

*Initial pain very severe but most recover with rest and analgesics

Question 11

What are the characteristics of lateral lumbar disc protrusion?

Answer 11

=> L5 and S1 roots commonly compressed

=> Slipped disc at L4-L5 or L5-S1 common (root number below the disc is affected)

=> Acute onset, spontaneous

=> Low back pain

=> Sciatica i.e. pain radiating from back to buttock and leg

=> Due to lifting, bending or minor injury

=> Ankle reflex loss ± weakness of plantar flexion (S1 root lesion)

=> Weakness of great toe extension (L5)

=> Sensory loss of affected dermatome

*Most sciatica resolves with rest and analgesia

Question 12

What is cervical spondylotic myelopathy?

Answer 12

Cervical spondylotic myelopathy => posterior disc protrusion

=> C4-C5 ; C5-C6 ; C6-C7 most common levels affected

=> Causes spinal cord compression

=> Due to congenital spinal narrowing, osteophytes, ligamentous thickening & ischaemia

=> Progressive difficulty walking

=> Development of spastic paraparesis

*Anterior cervical discectomy if cord compression severe

Question 13

What is the cauda equina syndrome?

Cauda Equina = SURGICAL EMERGENCY

Answer 13

Central lumbosacral disc protrusion which compresses the whole spinal cord

=> Acute onset : acute flaccid paraparesis

=> Bilateral flaccid lower limb weakness

=> Sacral numbness (saddle anaesthesia)

=> Loss of anal tone on PR

=> Retention of urine or bladder/bowel incontinence

=> Erectile dysfunction

=> Areflexia

*Urgent imaging and disc decompression is needed

Question 14

How are slipped discs diagnosed?

Answer 14

Neuro + MSK exam

Detailed history

X-ray

CT / MRI

Question 15

What are the complications of slipped disc?

Answer 15

Worsening symptoms i.e. pain, numbness and weakness

Permanent nerve damage

Cauda equina - incontinence or urine retention

Saddle anaesthesia (loss of sensation in inner thighs, back of legs and area around rectum)

Question 16

How are prolapsed discs treated?

Answer 16

Range from conservative to surgical

Conservative:

=> Immobility can lead to muscle weakness and joint stiffness, therefore try to remain as active as possible through stretching and low impact activities

=> Exercise program / physiotherapy that stretches and strengthens the back muscles.

=> Avoid heavy lifting / painful positions

=> Analgesics i.e. NSAIDs

=> Muscle relaxants

=> Gabapentin or duloxetine for nerve pain

Surgery:

=> Microdiskectomy

If symptoms do not subside in 6 weeks and slipped disc affecting muscle function

=> Laminectomy : disc may be replaced via an artificial one

=> Spinal fusion : disc removed and vertebrae may be fused together

Question 17

How to prevent herniated disc?

Answer 17

Exercise to strengthen trunk muscles which supports and stabilise the spine

Maintain good posture - reduces pressure off spine and discs

Healthy weight

Quit smoking