Thank you for posting your query.
in lower limbs
(legs) can occur due to a disease in corticospinal tracts, which extends from brain to the spinal cord
In your case, MRI
of the thoracolumbar spine has been done and it is normal. However, we still need to examine the brain and cervical spine
for any disease, as that too could cause spasticity of legs. Hence, your doctor has ordered for MRI of brain and cervical spine. CAT scan is not as sensitive and specific in finding out minor brain diseases or small lesions, hence it can not be relied upon 100%.
I hope it helps. Please get back if you have any more queries.
Dr Sudhir Kumar MD DM (Neurology)
Senior Consultant Neurologist