Imaging of the back

Question 1

what are the NICE guidelines R.E. imaging of lower back pain

Answer 1

1. 1.4 Do not routinely offer imaging in a non-specialist setting for people with low back pain with or without sciatica.
2. 1.5 Explain to people with low back pain with or without sciatica that if they are being referred for specialist opinion, they may not need imaging.
3. 1.6 Consider imaging in specialist settings of care (for example, a musculoskeletal interface clinic or hospital) for people with low back pain with or without sciatica only if the result is likely to change management.

1.1 Assessment of low back pain and sciatica
Alternative diagnoses
1.1.1 Think about alternative diagnoses when examining or reviewing people with low back pain, particularly if they develop new or changed symptoms.
Exclude specific causes of low back pain, for example, cancer, infection, trauma or inflammatory disease such as spondyloarthritis. If serious underlying pathology is suspected, refer to relevant NICE guidance for specific conditions.

Question 2

red flags for back pain

Answer 2

Under 20 and over 55
Pain after violent injury
Pain constant or increasing
History of cancer
Steroids
IVDU +/- HIV
Generally unwell / weight loss
Saddle anaesthesia / Sensory level
Sphincter disturbance
Bilateral loss of power
Structural deformity

Question 3

Ix for back pain

Answer 3

X-rays

MRI

CT

Bone scan

Special investigations (myelogram, DEXA, discogram)

Question 4

3 functions of the lumbar spine

Answer 4

Very strong for weight bearing on two legs (vertebral bodies)

Protect the delicate nerves travelling down to the legs (neural arch)

Incredibly flexible to allow movement (combination of discs, ligaments, joints and muscles)

Question 5

what level does the spinal cord terminate at?

Answer 5

L1/2

Question 6

what happens to the nerves at each disc level?

Answer 6

nerve root exiting
nerve root traversing the lateral recess
Remaining nerve roots in the thecal sac

Question 7

what should a normal lumbar spine look like in an x-ray

Answer 7

AP: no side to side curvature, increasing interpedicular distance, spinous processes aligned, well defined endplates

Lateral view: gentle lordosis, equal disc spaces, vertebral bodies aligned

Question 8

what is the signal intensity for each of the following on a T1 weighted MRI?

• fat
• fluid
• cord/nerves
• discs
• bone marrow

Answer 8

fat- high signal
fluid- low signal
cord/nerves- intermediate
discs- intermediate
bone marrow- higher than the disc

Question 9

what is the signal intensity for each of the following on a T2 weighted MRI?

• fat
• fluid
• cord/nerves
• discs
• bone marrow

Answer 9

fat- high
fluid- high
cord/nerves- intermediate
discs- high central, low periphery
bone marrow- less than the disc

Question 10

abnormalities that can be seen on a spinal MRI

Answer 10

Degenerative changes
Trauma
Infection
Tumour
Edge of film- surrounding organs

Question 11

changes seen on an MRI of degenerative disease

Answer 11

Loss of disc height & hydration
Reactive endplate changes 
Disc bulges/protrusions/extrusions
posterior & lateral
Facet joint hypertrophy & effusions
Ligamentous hypertrophy
Combination of the above:
Lateral recess narrowing
Foraminal narrowing 
Vertebral Canal stenosis

Question 12

signs and symptoms of cauda equina

Answer 12

Low back pain / unilateral or bilateral leg pain
Saddle anaesthesia / Incontinence / Impotence
Paralysis / reduced reflexes

Question 13

what does a burst fracture look like on imaging

Answer 13

pedicles get wider apart , vertebral body kinks backwards

Question 14

what can you assess on the edge of film?

Answer 14

Kidneys
Aorta
Lymph nodes
Uterus/Adnexae
Bowel
Lung bases