Definition
- disc bulge
- generalized outpouching of peripheral margin of annulus
- disc prolapse
- focal displacement of inner disc material
- protrusion
- disc bulging beyond limits of vertebral body
- extrusion
- disc material thru annulus fibrosus & PLL
- sequestered
- complete displacement with free disc fragment
Aetiology
Epidemiology
Incidence
- 56% of adults have disc bulging
- MRI scans show that between 20% & 35% of working age adults have asymptomatic disc herniation
- There is lifetime incidence of 2% for symptomatic disc herniation
- 80% of general population will experience back pain but only 2-3% will have sciatica
- mean onset = 35 years
- unusual < 20 years & > 60 years
- males = females (females present decade later than males)
Age
- Most lumbar disc herniations occur between 30 & 50
- Far lateral disc herniations occur in older age group (average age 65)
- Lumbar disc herniations before 30 tend to have hereditary aetiology
Site
- commonest site for prolapse is L4/L5 disc, then L5/S1 disc
Risk factors for back pain
- obesity
- smoking
- M:F
- Job: Lifting, vibration, sitting
- Job satisfaction ++
Anatomy
- prolapsed disc impinges on nerve root of second vertebra in motion segment; thus L5/S1 disc prolapse presses on S1 nerve root
- This is true for posterolateral prolapse, but for far lateral prolapse disc presses on nerve root of vertebra above; thus in far lateral L5/S1 disc prolapse L5 nerve root can be affected
Pathology
- Decreased water content & proteoglycan content
- Increased peripheral annular loading
- annular tear
- Decreased of disc space
- Increased stress at facet joints
- degeneration of facets with osteophyte formation
- traction spurs
- recurrent torsional strains
- lumbar spondylosis
- disc dessication
- collapse
- progressive facet arthrosis
- disc bulging
- osteophytosis
- abnormal kinematics
- further degeneration
- LDH occurs as result of annular degeneration leading to weakening of annulus fibrosis, leaving it susceptible to annular fissuring & tearing
- Two types of disc disease:
- 1. Compressive
- will have hard neurological signs
- 2. Chemical
- will not have hard neurological signs
- 1. Compressive
- Chance of resorption of disc fragment depends on its size & its nature
- Smaller disc fragments are less likely to be resorbed
- sequestrated disc fragments are more likely to be resorbed than contained fragments
- Best prognosis for resolution is large sequestrated fragment
Biochemical features of disc disease
- degenerated discs have higher concentrations of inflammatory mediators, such as IL-1, nitric oxide, PGE-2 & MMPs. Phospholipase A2 is found in higher concentrations in degenerate disc material
- discs also manifest stronger response to IL stimulus
- Degenerate discs have denser innervation than normal discs
Classification
Three pathoanatomical types of disc disease
- 1. Contained LDH
- disc fragment is bounded by annulus
- 2. Extruded LDH
- disc fragment escapes through defect in annulus but is in continuity with rest of disc
- 3. Sequestrated LDH
- free fragment
Anatomical position of herniation can be classified as:
- Central
- this can affect traversing nerve roots bilaterally, & cauda equina if large enough
- Posterolateral
- this is commonest site. herniation is to one side of PLL
- impingement of nerve root of lower vertebra
- Foraminal
- impingement of exiting nerve root (vertebra above)
- 10%
- impingement of exiting nerve root (vertebra above)
- Extraforaminal or far lateral
History
- fit adult of 20-45
- When stooping to pick something up patient suddenly experiences severe pain & is unable to straighten up
- Pain
- caused by irritation of annulus & posterior longitudinal ligament, which are both well innervated
- Pain in buttock & lower limb may be immediate or felt day or two later
- Increased with
- Coughing & straining
- sitting
- forward flexion
- sciatica/radiculopathy
- leg pain in dermatomal distribution
- constitutional symptoms
red flags
- young/old patient
- night pain
- rest pain
- bowel/bladder symptoms
- hx of Ca
- tumour, infection, trauma, cauda equina syndrome
Cauda equina syndrome
- rare
- ↑ risk
- stenotic canal
- features
- bilateral leg weakness
- saddle anaesthesia
- urinary retention
E>Examination
L>Look
- sciatic scoliosis
- knee on affected side may be bent to ↓ tension in affected nerve root
- lean towards affected side
- posterolateral disc herniation, where disc lies medial to nerve root, lean is towards painful side, to relieve tension
- lean away from affected side
- far lateral disc herniation lean is away from painful side
Fee>Feel
Mov>Move
- Decreased ROM
- All back movements, & particularly flexion & side bending away from prolapse are restricted
Spe>Special Tests
- Tension signs
- Most important, most predictive physical finding
- SLR (L5 S1)
- Straight leg raising is limited on affected side
- Cross straight leg raise
- major central disc prolapse
- more sensitive than ipsilateral straight leg raising test
- Sciatic stretch test
- refers to lowering leg slightly & dorsiflexing foot & was first described in 1901 by Fajersztajn, who also described crossed straight leg raising test
- bowstringing test
- may be positive, but is much less precise
- Lasègue’s test
- In 1881 his pupil Forst described lifting foot of supine patient with one hand & keeping knee extended with other
- He wrote, “It is only necessary to lift limb few inches for patient to experience acute pain at level of sciatic notch just at emergence of nerve” i.e. in buttock. This is not true sciatica, which should extend below knee
- Femoral stretch test (L3 L4)
Neurologic>Neurological examination
ss="wp-block-list">Waddell’s no>Waddell’s nonorganic tests
="wp-block-list">- extending leg in sitting position is negative but SLR in supine position is markedly positive
InvestigationsInvestigations
-block-heading">Indications>Indications-block-list">X-ray
X-ray-block-list">MRI
- MRIlock-list">
- changes of degenerative disc disease
- sensitive & specific but clinical correlation essential
- End plate changes:
- parallel bands of high or low signal adjacent to vertebral body end-plates
- Abnormal MRI – asymptomatic
- Age 20-40
- 20% HNP
- 30% bulge degeneration
- Age 40-60
- 20% HNP
- 60% bulge / degeneration
- Age 60-70
- 40% HNP
- 20% stenosis
- 90%% bulge / degeneration
- Age 20-40
CT scan
Modic Classificati>Modic Classification
lock-heading">Modic type I- Decreased signal intensity T1
- Increased signal intensity T2
- Found in 4% of cases
- Must be distinguished from disc space infection
- In disc space infection discs have signal intensity on T2 weighted images, & in degeneration discs have ¯ T2 signal intensity
Modic type 2
- Increased signal intensity T1
- Isointense or slightly ↑ intensity on T2
- Found in 16% of cases
- Represents fatty marrow conversion
Modic type 3
- Low signal intensity on both T1 & T2 weighted images representing bony sclerosis seen on plain films
Differential Diagnosis>Differential Diagnosis
-list">- In adolescents
- infection
- benign tumour
- spondylolisthesis
- elderly
- compression fracture
- malignant disease
- Lyme disease
- Diabetic amyotrophy
- Multiple sclerosis
- Idiopathic lumbar plexopathy
- All of these four conditions can present with painful radiculopathy & subtle sensory changes
Treatment
Treatment-heading">Nonoperative managemen>Nonoperative management
-list">- Education
- Lifestyle
- Weight loss
- Quit smoking
- Physical therapy
- Bed rest should be for no more than 2-3 days
- exercise (swimming, biking, walking), abdominal/low back stretching & strengthening
- Orthotic
- nil
- Medications
- Injections
- prospective trial has demonstrated benefits of series of up to 4 epidural nerve root injections, with reduction in need for surgery
- Nonoperative management will fail & require surgery in around 15%
Operative ManagementOperative Management
-heading">Types- Discectomy
- Open vs scope
- Laminotomy
Indications for discec>Indications for discectomy
-heading">Absolute- Cauda equina syndrome.
- within 48 hours of onset
- Rapidly progressive motor deficit
Relative
- Persistent sciatica &/or neurologic deficits despite 6 weeks of conservative therapy
- Recurrent sciatica &/or neurologic deficits
- Significant motor deficit with positive sciatic tension signs
- Disc herniation into stenotic canal
- Unremitting pain – disabling
Surgical candidate
- 1. Sciatica
- 2. Abnormal neuro finding
- often subtle
- 3. Tension sign
- 4. Confirmatory MRI
- 5. failed nonoperative Tx
When considering surgical treatment for patient with relative indications for surgery four factors need to be considered:
- Duration of radicular symptoms
- Quality & severity of symptoms
- Type & size of herniation
- Contained, extruded, sequestered
- Small vs. large
- Presence or absence of spinal stenosis
laminotomy & discect>laminotomy & discectomy
ist">- 95% relief of leg pain
- 15-30% persistent back pain
- neuro recovery
- 50% motor or sensory
- 25% reflex
Procedures
Procedureseading">Posterolateral herniatio>Posterolateral herniation
ist">Far Lateral Disc
>Far Lateral Discist">- popularized by Wiltse (muscle-splitting approach)
- Make incision 5 cm from midline, followed by blunt dissection of paraspinal muscles
- At this point, take radiographs to verify level & clear transverse processes of soft tissues
- Enter intertransverse ligaments & fascia with knife or curet, then remove those structures between transverse processes
- Identify nerve, which is usually 2 to 4 mm anterior to fascia & directed at 45° angle
- Follow nerve medially & identify disc
Management of Durotomy
- Gelfoam & Tisseel
- Water tight closure in layers
Complications
Complicationsading">Intraoperative
Intraoperativest">- essential to check position intraoperatively with XR
- avoidable if ALL is not broached. Treatment of pulsatile bleeding is to close wound immediately, turn patient over & do laparotomy to identify site of bleeding. Mortality can be up to 50%. Complications can include false aneurysm & AV fistula
- Nerve root – higher rate with conjoined nerve roots
- Hypogastric plexus, leading to retrograde ejaculation
- Watertight closure & repair
- Patch
- Subarachnoid drain for 4-5 days
- Recurrent HNP 3-11%
- Vascular catastrophe
Early postoperative
>Early postoperative">Late postoperative
>Late postoperative">- There is no rate in reduction of recurrent disc herniation with aggressive debridement of disc space, so only free fragments should be removed. Revision discectomy may be required in up to 15% of patients; recurrent disc herniation doesn’t respond to nonoperative management as well as primary herniation
- 3-6 weeks posterior op
- severe onset of buttock pain
- MRI with GAD
- ↑ signal in disc space
Prognosis
Prognosis>Natural History
Post>Natural Historyp>
- 60% recover in 1 week
- 90% 1 month
- 95% recovery in 3 months with low back pain
- 75% recovery in 3 months with sciatica
- op vs nonop
- results equal at 4 years
- almost equal at 1 year
- due to prevalence of back pain
- nonop Treatment best usually
- There is favorable response to nonoperative treatment, even in presence of neurological deficit
- Thus, isolated neurological deficit without function impairing pain doesn’t warrant surgical intervention
- Several studies have shown that most herniated discs reabsorb with time, particularly large & herniated or extruded discs
- Conservative measures should be trialled for 6 weeks before surgery
- For patients with persistent pain & neurologic compromise unresponsive to conservative measures surgery should not be delayed beyond 6 months because of risk of chronic disability
Results
- ResultsOptimal treatment for static motor loss without pain (does this exist?) is controversial & there is no evidence that surgical decompression will result in speedier return of function than non-surgical care
- Surgery
- 90% relief of leg pain
- 30% persistent back pain
- Neuro recovery
- 50% motor
- 50% sensory
- 25% reflex