Myelography - Contrast Radiography of the Spinal Cord

Myelography

Indication to identify spinal lesions that are unable to be identified on a plain radiograph

Myelography involves ..

• An injection of a contrast agent into the subarachnoid space to highlight the spinal cord

• General anaesthesia is required

Myelography - Indications for use

• Paresis or paralysis

• Ataxia

• Spinal pain

Myelography may be used to identify compression of the spinal cord, inflammation and CSF obstruction. Also helps to identify whether lesions are extradural, intradural or intramedullary. Potential complications include ..

• Seizures post anaesthesia recovery

• Spinal cord damage if the needle is placed incorrectly

• Septic meningitis

• A worsening of the neurological signs for which the patient initially presented

What type of contrast medica is used for these studies?

A low osmolar, non-ionic, water soluble iodine-based contrast agent

Where can it be injected?

• Site for cisternal puncture

• Site for Lumbar puncture

Site for cisternal puncture

The cisternal magna at the base of the skull

Cisterna Megna Preparation

• Aseptic preparation

• Lateral recumbency

• Flex head to 90° and hold in place

• Elevate nose to medial plane (30 to 45° angle)

Site for lumbar puncture

Lumbar spinal canal, usually at L3-4 or L4-5

Lumbar puncture patient preparation

Position patient in lateral recumbency and flex the spine and hips

Why is it often easier to inject contrast media into the cisternal magna?

CSF flows more readily from this site

Care must be taken when injecting into the cisterns magna as the contrast media is under gravity. Excessive pressure during administration may cause ..

A backflow towards the brain → seizures

This is particularity important if obstructed lesions are suspected

Speed is essential during myelography as the contrast media is ..

Rapidly absorbed into the bloodstream, for this reason, automatic or digital processing should be available

Nursing care post myelography - patients head

Keep the patients head elevated above the body to prevent the contrast medial flowing back towards the brain and causing seizures. This should be continued until the patients has fully recovered.

Nursing care post myelography

• Close monitoring during recovery and record observations

• Inform the Veterinary Surgeons immediately if fitting occurs

• These patients should be under constant supervision and would be within a high-dependency/intensive care setting if in a referral hospital

Why should myelography only be performed if the outcome will influence how the case is managed and benefit the patient?

This imaging technique involves many risks to the patient

Myelography is no longer commonly performed in practice due to ..

CT/MRI

Other contrast studies

• Arthrography

• Angiography

Arthrography - used for ..

• Elevate peripheral joints, in particular, the shoulder

• Osteochondrosis

Arthrography - preferred contrast

Positive contrast arthrogram preferred

Arthrography - Contrast studies

Negative and double contrast studies may cause air bubbles to mix with the synovial fluid in the joint space interpretation difficult

Arthrography

Not a routine procedure → Performed most commonly in orthopaedic referrals. CT and MRI often used instead of this imaging technique

Angiography - used for ..

• To visualise and evaluate blood filled structures

• Congenital defects and cardiac malformations

Angiography - Contrast media used

Positive contrast used (WSIB - Water soluble iodine based)

What blood filled structures does Angiography visualise and evaluate?

• Arteries

• Veins

• Heart chambers

Angiography

Not a routine procedure → Performed most commonly in referral practice