Diagnostic Tests

Question 0

X ray imaging

Answer 0

Limited in ability to view soft tissue (muscles, discs, nerves) but still used to confirm/exclude tumours, infections, fractures.
Relatively inexpensive
Can sometimes confirm suspicion of herniated disc

Question 1

Lasegues sign

Answer 1

Straight leg raise. Done during physical exam to determine if patient with lower back pain has underlying herniated disc.
With patient lying on floor on their back, the examiner lifts patient leg while knee is straight. If patient experiences sciatic pain when straight leg between 30 and 70 degrees then the test is positive and there is a herniated disc.

Question 2

MRI

Answer 2

Diagnostic test that produces 3D images of body structures using powerful magnets and computers.
Shows spinal cord, nerve roots, surrounding areas and enlargements,tumours etc. Shows soft tissue better that CT.

Question 3

T1 weighted MRI

Answer 3

Water appears dark, fatty tissues bright.
Have appearance of anatomical brain sections, with CSF being grey and white matter being white. Resolution of fine anatomical detail is usually seen better in these.

Question 4

T2 MRI

Answer 4

Water appears bright and lipid dark.
Clearest visualisation for protruded disc material in spinal cord.
So CSF appears very bright, brain oedema, gliosis and gray matter appear bright but less than CSF. Myelinated areas are dark. Makes areas of brain abnormalities easier to see than T1.
However bright CSF may impair viewing of parenchyma adjacent to ventricles or pia.

Question 5

Advantages of MRI

Answer 5

• distinguishes between white and grey matter
• cord and nerve roots images clearly
• MRI has greater resolution than CT
• no radiation
• MR angiography images vessels without contrast
• MR images soft tissues
• tumours, infections, MS plaques, haemorrhage

Question 6

Ankle jerk reflex

Answer 6

When achilles tendon is tapped when foot is dorsi flexed.
Positive result is jerking of foot upward towards plantar
Reflex mediated by S1 spinal segment of sc.
Could be indicative of sciatic nerve pathology. Reflex usually absent in herniations at L5-S1 level

Question 7

Treatment for disc herniations

Answer 7

• otc analgesics
• rehabilitations
• discectomy: surgical removal of central portion of iv disc, nucleus pulposus. Also a laminotomy is involved to permit access to iv disc by removing a small piece of bone (lamina) from affected vertebra, allowing surgeon to see iv disc herniation better.