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- 3 sources of pain:
- Discogenic pain as annulus and PLL innervated by sinuvertebral nerve from ventral ramus
- Dorsal Ramus gives rise to medial branch supplying facet joins
- Ventral Ramus gives rise to:
- 1. Sinuvertebral nerve (from ventral ramus) ➔ posterior annulus, Dura, PLL
- 2. Gray ramus Communicans (from sympathetic ganglion)➔ anterior annulus, ALL
- Only the outer third of a healthy annulus is innervted. Inner two-thirds is completely avascular and aneural
- Chemicals causing pain - phospholipase A2, Interleukins 1, 2, TNF alpha
- Radicular pain from nerve compression
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- L4/5 then L5/S1
- (degenerative Spondylolisthesis is also L4/5. Dysplastic is L5/S1)
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- Disc bulge - diffuse symmetrical oupouching of annulus fibrosus
- Protrusion – intact AF - Base > AP dimension
- Extrusion – AF disrupted - AP dimension > base
- Sequestered – not continuous
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- CLFE
- Central stenosis - will hit traversing roots
- Lateral recess aka subarticular = begins at the medial border of the superior articular process and extends to the medial border of the pedicle - will hit traversing roots aka " paracentral" when used to describe disc
- Foraminal recess [Mid-zone] = between medial and lateral border of pedicles - hit exiting roots
- Extra-foraminal/ Far lateral recess [Exit zone] = lateral to lateral border of pedicle - exitting roots
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- It is the process anteriorly
- SAP is on the outside
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- Paracentral aka lateral recess 90-95%!
- PLL is weakest here
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- Cervical spine C6 nerve root travels under C5 pedicle (mismatch)
- Lumbar spine L5 nerve root travels under L5 pedicle (match)
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- Lumbar spine - paracentral disc and foraminal disc will affect traversing root
- C-spine - central and foraminal disc will affect the same nerve root
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- Straight leg raise
- Lesague's - foot dorsiflexion
- Bow string sign = flex knee, then compress popliteal fossa
- Contralateral SLR - central disc herniation
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- Conus Medullaris
- More proximal as end at L1
- More symmetrical
- Presence of UMNL signs - clonus, down going babinski
- Cauda Equina
- Weakness more distal
- Asymmetry
- No UMNL signs
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- Based on the North American Spine Society NASS workgroup systematic review
- 50% recover in 1 month, 80% significant improvement in 3 month
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- Analgesia, PT
- Nerve root block
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- P - prone on wilson frame to open up interlaminar space
- Localise with II
- I - midline incision down to supraspinous ligament
- Paraspinal muscles retracted laterally (preserve joint capsule)
- Ligamentum flavum incised and window created
- Laminotomy on inferior edge of upper lamina
- Locate and protect nerve root
- Look for sequestered disc if present
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- Yes - you can do L5/S1 (widest) discectomy via Fenestration of the ligamentum flavum
- Yes - you can do far lateral disc via wiltse approach and avoid laminectomy
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- Dural tears - get help from Neurosurgery
- nerve root injury
- Epidural bleeding,
- Infection, discitis
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- Micro - shorter hospital stay, lower pain scores
- No difference in post op pain, occupational impact or recurrence
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- Aware of the SPORT Trial and the Maine Lumbar Spine Study
- SPORT trial was a RCT of 501 patients.
- Intention to treat analysis - no difference
- As-treated analysis shows significantly greater improvement in pain, function, satisfaction over 8 years.
- However High cross over rates of up to 60% thus observed effects for Intention-to-treat was small.
- MLSS was a cohort study of 500 patients
- Patients with sciatica found to respond better with surgery at 1 and 4 year follow up but employment outcomes similar
- No difference in back pain
- Revision rates lower at 10 years 23% vs 39%
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- Robert Keller et al. Evaluate effectiveness of surgery for herniated lumbar disc
- Prospective cohort study; not randomized ; 507 patients
- Compared op vs non op; Patients who underwent op [Open discectomy] had worse symptoms based on Sciatic Bothersome Index
- Patients with sciatica reported substantially better outcomes with surgery at 1 year and 4 year follow up BUT employment outcomes similar
- At 10 years, op vs non op similar improvement in low back pain, satisfaction BUT better leg pain and functional scores
- Surgery lower revision rates at 10 years (23% vs 39%)
- Surgery had little advantage for those with little symptoms
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- I will consent by discussing with patient the indications, alternatives, risks and expectations of outcomes
- Indications - prevent OA/ neurology/ paralysis/ halt progression
- Alternatives - non operative but may get worse
- Risks - GA vs Specific; Early vs Late
- Expectations of outcomes - wound healing, bone healing,
THORACIC DISC HERNIATION
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- Transpedicular via posterior approach (Jon tan)
- Remove pedicle and part of the rib
- May need to sacrifice an intercostal nerve root
- Transthoracic (anterior approach) - most preferred. Can be either open or thoracoscopic
- Lateral extracavitary
- Costotransversectomy
