C. Lumbosacral disc herniation – Explanation
Sudden onset of lower back pain and felt more during forward bending or similar
movement like getting up from bed favours the diagnosis of lumbosacral disc herniation
INTERVERTEBRAL DISC PROLAPSE, SCIATICA
- A herniated disc is most common in those aged below 40 years, whilst degeneration
of discs tends to affect those aged over 40 years. - It most commonly occurs at the L5/S1 level (L5/S1 disc and L4/5 disc prolapse
account for more than 95% of lumbar disc prolapse) - If there is nerve entrapment in the lumbosacral spine, this may lead to symptoms of
sciatica - Large herniations can compress the cauda equina
The term sciatica in UK is used as a substitute for pain radiating to legs relating to
compressive spinal pathology. This is a preferred term as patients and medical staff
tend to use it more frequently than radiculopathy.
Symptoms of sciatica
- Unilateral leg pain which radiates below the knee to the foot/toes
- Symptoms can be acute or gradual
- Leg pain more severe than the back pain
- Associated with numbness and paraesthesia
- Pain usually relieved by lying down
- Pain worsens when walking or prolonged sitting
Always think of the following when dealing with sciatica
- Look out for features of:
o Spondyloarthritis
o Spinal injury
o Metastatic spinal cord compression or cancer
- Look out for cauda equina syndrome symptoms
o Faecal incontinence
o Urinary retention
o Saddle or perianal paraesthesia
What about imaging?
- Imaging such as MRI is usually not necessary unless there are red flags or if it is
likely to change management plan.
Management
- If signs and symptoms are not too severe, it usually resolves spontaneously in about
six weeks but can also last for months - Pain relief such as NSAIDs would be suitable
- For neuropathic pain in sciatica medications include amitryptyline, gabapentin,
pregabalin and duloxetine – Amitriptyline is usually the medication of choice as ifit is
the cheapest and there is no evidence that the others are superior - If there are red flag signs such as the possibility of cauda equina syndrome, refer to
an orthopaedic surgeon or a neurosurgeon URGENTLY
Spinal cord compression or cauda equina syndrome are neurological emergencies that
require immediate referral and intervention!
SCIATICA, SITE OF COMPRESSION
| Site of compression | Features |
|---|---|
| L2 nerve root compression (uncommon) |
Anterior thigh pain Positive femoral stretch test |
| L3 nerve root compression | Sensory loss over anterior thigh Absent or decreased knee jerk Positive femoral stretch test |
| L4 nerve root compression | Sensory loss of anterior aspect of knee Absent or decreased knee jerk Positive femoral stretch test |
| L5 nerve root compression | Sensory loss dorsum of foot Weakness in ankle dorsiflexion Reflexes intact |
| S1 nerve root compression Sensory | Sensory loss posterolateral aspect of leg and lateral
aspect of foot |
Positive femoral stretch test
- Positive if the patient experiences anterior thigh pain when prone with hip extension
with maximal knee flexion - Indicates L2, L3 or L4 root pathology
- See video https://www.youtube.com/watch?v=h5YjDsngTN8
Positive straight leg raise test
- If the patient experiences sciatic pain when the straight leg is at an angle of between
30 and 70 degrees - Indicates herniated disc as cause of pain
- See video https://www.youtube.com/watch?v=uo0vZZdN854
