These findings are typical for multiple sclerosis.
These "plaques" are evidence of damage to the protective sheath around the axons - demyelination. They are usually bright/high signal on T2 and especially evident on FLAIR sequences. Also, active areas of demyelination enhance with contrast - as the right periventricular lesions do in this case (consistent with his presentation of left sided sensory changes).
MRI is the best investigation to chartacterise these lesions. As said, CT does not give enough information and also as the majority of MS patients are young to middle-aged adults, recurrent CTs carry risks.
Thanks to Dr Frank Gaillard for originally contributing the case and the discussion. The original is available here.