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What is Myelography?

What is Myelography?. Radiographic examination of: spinal canal, spinal cord, and nerve roots using contrast agent injected through a needle into space around spinal cord. Central nervous system. 2 basic parts Brain Spinal Cord. Spinal Cord. Continuous with medulla oblongata

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What is Myelography?

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  1. What is Myelography? Radiographic examination of: spinal canal, spinal cord, and nerve roots using contrast agent injected through a needle into space around spinal cord

  2. Central nervous system 2 basic parts Brain Spinal Cord

  3. Spinal Cord • Continuous with medulla oblongata • Extends from brain to approximately L2 • Connected to 31 pairs of spinal nerves

  4. Meninges Layered coverings of brain and spinal cord - Protects them from rubbing against bone and skull Pia mater- inner sheath Highly vascular Arachnoid- central sheath Separated from pia mater by subarachnoid space Dura mater- outer sheath Outermost, protective layer

  5. Ventricles 4 cavities within brain Filled with cerebral spinal fluid (CSF) Communicate with each other through interventricular foramina)

  6. Cerebral Spinal Fluid Clear fluid produced in ventricular system Protects brain from striking cranium when head jolted Provides buoyancy -brain can float and be supported against gravity Maintains chemical stability: Excretes waste productsto blood Transports of hormones to other areas of brain

  7. Hydrocephalus “Water on the brain" Abnormal accumulation of CSF in ventricles due to blockage of outflow from ventricles May cause: • Increased intracranial pressure • Progressive enlargement of head of infants and children • Convulsions • Tunnel vision • Mental disability

  8. Hydrocephalus

  9. Shunt to control flow of CSF Valve controlled by magnet applied by Dr. to regulate flow of CSF Tech takes x-ray to check if tiny radiopaque “clock face” of valve has actually been changed and to what degree

  10. Myelography Outpatient radiographic exam of spinal cord performed by radiologist Detects abnormalities of spine, spinal cord, or surrounding structures Contrast material injected into fluid-filled space around spinal cord Fluoroscopy and overhead x-ray’s taken CT and MRI have largely replaced exam (except for pacemakers or metallic spinal fusions)

  11. Myelography Indications Intraspinal abnormalities Nerve root abnormalities Disk prolapse(slipped disk) Spondylosis- degenerative arthritis of spinal vertebra and related tissue Spondylolisthesis Spinal stenosis(spinal canal narrows and compresses spinal cord and nerves) Tumors Metastases

  12. Preliminary Radiographs AP Lateral Both anterior oblique views Lateral L5-S1

  13. Purpose of Preliminary Radiographs To exclude pathologies that wouldn’t need myelography Determine accurate bony anatomy Distinguish congenital abnormalities Compare later with myelogram, MRI and CT images

  14. Contrast Agents Early myelograms used air Injected via lumbar puncture In 1922- iodized poppy seed oil (accidentally discovered - had no apparent side effects) Late 1970’s – nonionic, water-soluble compounds • demonstrated lower neurotoxicity-(ability of drug or other agent to destroy or damage nervous tissue)

  15. Injections Sites Into subarachnoid space (space between arachnoid and pia mater) Cistern(below occipital bone -can be hazardous because the needle is inserted close to brain stem) Cervical spine Thoracic spine Lumbar spine (most common)

  16. Lumbar Myelogram Lumbar puncture: needle inserted under fluoroscopic guidance until fluid appears (CSF may be taken for analysis) Contrast material injected Flow monitored fluoroscopically Pt. tilted trendelenberg and reverse-trendelenberg: to control flow of contrast during spot films & overheads

  17. Radiographs taken during exam: Generally: cross table lateral and PA Why not routine views? 1. Pt has needle in spine 2. Don’t want to change contrast position by rotating pt

  18. Myelography Accuracy Rate Compared with surgical findings: Myelography – 81% CT – 57% CT and Myelography together - 84% MRI (alone) – 96%!

  19. Cervical Myelograms

  20. Cervical Myelography Radiographs Overheads: PA PA Oblique projections Cross-table lateral films (flexion and extension) Maintain head in acute extension -avoid flow of contrast into brain!

  21. Pneumoencephalography MRI and CT make it obsolete Introduced in 1919 Performed extensively throughout late 20th century Small amount Cerebrospinal fluid drained from around brain Then air, helium, or oxygen injected into lumbar subarachnoid space to provide contrast

  22. Pneumoencephalography cont’d Pt turned upside down in special chair that can rotate vertically 360 degrees to get air to fill ventricals Extremely painful, very dangerous Headaches and severe vomiting common side effects Replacement of spinal fluid was by natural generation- took as long as 2-3 months

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