Back pain Flashcards
Sciatica : Anatomy and supply
- The spinal nerves L4 – S3 come together to form the sciatic nerve.
- The sciatic nerve exits the posterior part of the pelvis through the greater sciatic foramen, in the buttock area on either side.
- It travels down the back of the leg
Supply :
* Sensation: to the lateral lower leg and the foot.
* Motor to the posterior thigh, lower leg and foot.
Sciatic nerve lesion : features and causes
1 . Features of sciatic nerve lesion
* Motor: paralysis of knee flexion and all movements below knee
* Sensory: loss below knee
2 . Causes
* fracture neck of femur
* posterior hip dislocation
* trauma
Sciatica : Clinical features
1 . Unilateral pain from the buttock radiating down to ;
* the back of the thigh to below the knee or feet.
* “Electric” or “shooting” pain.
2 . Paraesthesia (pins and needles), numbness and motor weakness.
Bilateral sciatica is a red flag for cauda equina syndrome
Sciatica : Causes
The main causes of sciatica are lumbosacral nerve root compression by:
* Herniated disc
* Spondylolisthesis (anterior displacement of a vertebra out of line with the one below)
* Spinal stenosis
Sciatica : Diagnosis
-
Sciatic stretch test
* The patient lies on their back with their leg straight.
* The examiner lifts one leg from the ankle with the knee striaight until the limit of hip flexion is reached (usually around 80-90 degrees).
* Then the examiner dorsiflexes the patient’s ankle.
* Sciatica-type pain in the buttock/posterior thigh indicates sciatic nerve root irritation.
* Symptoms improve with flexing the knee.
Sciatica : Management
Neuropathic medication but not gabapentin or pregabalin, leaving at the main choices of:
* Amitriptyline
* Duloxetine
Specialist management options for chronic sciatica include:
* Epidural corticosteroid injections
* Local anaesthetic injections
* Radiofrequency denervation
* Spinal decompression
Chronic lower back pain : Management
STarT Back Screening Tool : stratify the risk of a patient presenting with acute back pain developing chronic back pain.
1 . Low risk of chronic back pain
* Self-management/ Education/ Reassurance
* Analgesia
* Staying active and continuing to mobilise as tolerated
2 . Medium or high risk of developing chronic back pain include:
* Physiotherapy/ Cognitive behavioural therapy
The NICE clinical knowledge summaries advise for analgesia:
1. NSAIDs (e.g., ibuprofen or naproxen) first-line
2. Codeine as an alternative
3. Benzodiazepines (e.g., diazepam) for muscle spasm (short-term only – up to 5 days)
Spinal stenosis : Definition
- Narrowing of part of the spinal canal, resulting in compression of the spinal cord or nerve roots.
This usually affects the lumbar spine - lumbar spinal stenosis,
Spinal stenosis : Clinical features
- Gradual onset
-
Intermittent neurogenic claudication - lumbar spinal stenosis with central stenosis
* Lower back pain
* Buttock and leg pain
* Leg weakness - Intermittent symptoms
* symptoms are absent at rest and when seated but occur with standing and walking.
* Bending forward (flexing the spine) expands the spinal canal and improves symptoms.
* Standing straight (extending the spine) narrows the canal and worsens the symptoms.
Spinal stenosis : Investigation
- MRI is the primary imaging investigation for diagnosing spinal stenosis.
- Investigations to exclude peripheral arterial disease(e.g., ankle-brachial pressure index and CT angiogram) may be appropriate where symptoms of intermittent claudication are present.
Discitis : Definition
iscitis is an infection in the intervertebral disc space. It can lead to serious complications such as sepsis or an epidural abscess.
Discitis pathophysiology
- Discitis is usually due to haematogenous spread to the vertebrae implying that the patient has had a bacteraemia and seeding could have occurred elsewhere
- Potentially secondary to endocarditis
- Bacterial
- Staphylococcus aureus/ is the most common cause of discitis
Discitis : Clinical features
1 .Back pain
2 .General features
* pyrexia,
* rigors
* sepsis
3 . Neurological features
* e.g. changing lower limb neurology
* if an epidural abscess develops
Discitis : Diagnosis
- Imaging: MRI has the highest sensitivity
Discitis - Management
- IV antibiotics : 6 - 8 weeks
- Transoesophageal ECHO to r/o endocarditis
Prolapse disc : Examination
Assess which nerve root is affected
L2-L4 : Femoral nerve
Femoral stretch test
a patient lies prone, the knee is passively flexed to the thigh and the hip is passively extended
L5-S1 Sciatic stretch test
with the person lying supine, flex the hip gradually with the knee extended.
Femoral nerve - anatomy
Femoral nerve
Origin L3-L4 -exits via pelvis
Motor supply : Supplies anterior thigh muscles
* Hip flexion
* Knee extention
Branches;
1. Anteriorly - Anterior cuteneous nerve
2. Posteriorly - Saphenous nerve
Saphenous nerve
- Posterior branch of the femoral nerve
Sensory supply : Skin of medial leg and foot
L3 nerve compression : Clinical presentation
Effects : Femoral nerve and Anterior cutaneous nerve
1. Sensory loss over anterior thigh ( Anterior cutenous nerve)
1. Weak hip flexion, knee extension and hip adduction (Femoral nerve)
1. Reduced knee reflex
1. Positive femoral stretch test
L4 nerve compression : Clinical presentation
Affects;
Femoral nerve
* Weak knee extension and hip adduction
* Reduced knee reflex
* Positive femoral stretch test
Spahenous nerve
* Sensory loss anterior aspect of knee and medial malleolus
Tibial nerve : Anatomy
Posterior branch of sciatic nerve
* Motor : Posterior calf muscles
plantar flexion of the ankle, flexion of the great toe
* Sensory : the posterolateral leg, lateral foot and the sole of the foot.
L5 nerve root compression : Clinical presentation
Affects;
1 . Common fibular nerve
* Sensory loss dorsum of foot
2 . Tibial nerve
* Weakness in foot and big toe dorsiflexion
* Reflexes intact
* Positive sciatic nerve stretch test
