intervertebral discs structure, movement, and herniation mike pichette, casey moran, kristen palmer
TRANSCRIPT
Intervertebral DiscsStructure, Movement,
and Herniation Mike Pichette, Casey Moran, Kristen Palmer
Disc Layers & Tissue Structure
Annulus Fibrosis
• Concentric fibrocartilage rings
• Fibers oblique and at right angles
• Peripheral vascularity
Nucleus Pulposus
• Gelatinous central core
• Mostly water, the rest is collagen
• Avascular
Symphysis Joints
Thickness varies
No disc C1 and C2, L5/S1 most inferior
http://dmm.biologists.org/content/4/1/31/F1.large.jpg, http://www.spinemd.com/cache/images/Medtronic_disctobone_300_274_80.jpg, http://www.chirogeek.com/Anatomy%20Page/Images/Anatomy%20PG/blood-supply.jpg
Age Related Changes
AF thickens and ↑ load bearing
NP dehydrates, cellular changes
• ↓ Elastin and proteoglycans
• ↑ Collagen
Disc replacement
• Plastic and cobalt-chrome
• Viscoelastic polymer and beaded titanium
http://www.biomedcentral.com/content/figures/1746-6148-10-3-1-l.jpg, http://www.sonsa.org/images/ddd2.jpg, http://cdn.trustedpartner.com/images/library/TheSpineCenter2012/Content/ArtificialDisc300.jpg, http://medcitynews.com/wp-content/uploads/freedom-lumbar-disc-509-x-391.jpg
Vertebral Disc HerniationHerniation:
• Nucleus Pulposus moves out of place and breaks open, pressing into nerve root
Lumbar region most common
• Sciatica (pain from lower back into leg)
Symptoms:
• Dull or sharp pain, muscle spasms or cramping, leg weakness, numbness, tingling
Increased risk:
• Aging, lifestyle choices, poor posture, incorrect/repetitive lifting
Image: http://bhpain.com/yahoo_site_admin/assets/images/disc_herniation.138191338_std.gif
Stages of Disc Herniation
1. Disc Degeneration:
Aging causes NP to weaken
2. Prolapse:
Disc changed position leads to impingement
3. Extrusion: Nucleus Pulposus breaks through annulus fibrosus (no herniation)
4. Sequestered Disc:
Nucleus Pulposus breaks through the annulus fibrosus (HNP)
Miyakoshi et al. Case Study53-year-old Japanese male
Symptoms: sudden onset of incomplete paraplegia after lifting a heavy object
• Motor strength: 0/5 R LE and 0-2/5 L LE
• Sensory loss below level of umbilicus
• Urinary incontinence
MRI results: posterior epidural mass compressing the spinal cord at T9-T10 level
Case Study Cont.Surgical procedures: laminectomy at T9-T10,
facetectomy, removal of mass lesion, and posterior instrumented fusion
Intra-operative diagnosis: posteriorly migrated thoracic disc herniation
Prognosis: resumed to walking without a cane by 4 weeks post surgery
Discussion:
• Only 0.15% to 4% of all symptomatic disc herniations occur in thoracic spine
• Only 5 cases (in 2013) of posteriorly migrated thoracic disc herniation had been reported
• Should be considered for differential diagnoses
ReferencesColorado Comprehensive Spine Institute. (n.d.). Retrieved June 6, 2015, from http://www.coloradospineinstitute.com/subject.php?pn=cond-lumbardisc-3
Kim, I. S., et al. (2008). Posterior epidural migration of thoracic disc fragment. Journal of Korean Neurosurgical Society, 43(5): 239-241. doi: 10.3340/jkns.2008.43.5.239.
Marieb, E. N., & Hoehn, K. ( 2013). Human anatomy and physiology (9th ed). Glenview, IL: Pearson Education, Inc.
Miyakoshi, N. et al. (2013). Posteriorly migrated thoracic disc herniation: a case report. Journal of Medical Case Reports, 7: 41. doi: 10.1186/1752-1947-7-41.
Moore, K. L., Agur, A. M. R., & Dalley, A. F. (2011). Essential clinical anatomy (4th ed.). Baltimore, MD: Lippincott Williams & Wilkins.