RD MCQ 2013 August - WA:formatted

Question 1

Myelination

a. Myelination of the optic tracts is complete by 2 months of age
b. Myelinated white matter is brighter than gray matter on T1WI
c. Isointense transition phase is seen between 20-24 months where there is reduced grey-whitedifferentiation

Answer 1

b. Myelinated white matter is brighter than gray matter on T1WI

Question 2

Regarding CNS neoplasms which is true?

a. Ependymoma and hemangioblastoma are the most common in adults
b. Myxopapillary ependymoma in the cervical spine
c. Ependymoma causes increased production of CSF
d. Medulloblastoma Midline vermian mass

Answer 2

*LW:
Regarding CNS neoplasms which is true?

a. Ependymoma and hemangioblastoma are the most common in adults: FALSE
- Most common CNS tumour in adults is Mets.
- Most common primary intra cranial neoplasm is glioblastoma.

b. Myxopapillary ependymoma in the cervical spine: FALSE
- Myxopapillary ependymoma filum terminale / conus medullaris.

c. Ependymoma causes increased production of CSF: False (I think).
- Ependymoma arise from radial glial cells, and with mass affect cause hydrocephalus, thus unlikely to secrete CSF.

d. Medulloblastoma Midline vermian mass: True:
- Radiopedia states: vast majority (94%) of medulloblastomas arise in the cerebellum and the majority of these, from the vermis (75%).

Question 3

60yo M with prostate treated 2 years ago. Now develops acute lower limb weakness, sensation intact in ED, by the time the patient has MRI power 2/5. MRI with contrast structurally normal. Most likely?

a. Spinal cord infarciton
b. Leptomeningeal mets
c. Radiation myelitis

Answer 3

*LW:
Favoured answer is Radiation myelitis, delayed type:

• Delayed radiation myelopathy (progressive radiation myelopathy) is a rare but serious complication of radiotherapy. It usually occurs in 9-18 months after completion of radiotherapy.
• MRI may be normal in radiation myelopathy. Suggested features are:
• intramedullary hyperintensity on T2 sequences
• marginal/heterogeneous enhancement in T1 postcontrast sequences
• spinal cord oedema
• cord expansion
• haemorrhagic changes in severe cases with poor outcome
• Central region of spinal cord is more affected as it contains spinal grey matter with myelinated tracts at the periphery.

[Why else would they go on about prostate treatment, without going into athersclerotic / surgical risk factors for infarct]

Spinal cord infarction: False
- Usually acute onset, Initial symptoms include severe back pain (60-70%), loss of bladder control (60%) and bowel control (40%), and counter-intuitively given that the anterior cord is most commonly involved, the first symptom noticed is more frequently sensory (60%).

**LJS - agree. None of the answers are great. According to statdx radiation myelitis presentation is slower progression of sx that transverse myelitis (which is subacute - over days). Nothing else on the list would give normal MRI though

Previous answer:
a. Spinal cord infarction I think, because of rapid onset. Delayed radiation myelopathy is usually progressive.