Right arm/hand numbness/tingling for 4 days most of the day, had brain mri 8 mo ago that showed demeylination measuring 2mm in the left corona radiata, is this related?

The corona ratiata (CR) radiate to all parts of the cortex. The CR contains decussating motor tracts that could cause symptoms to the opposite side of the body. That does not mean that the ill-defined demyelination you site is the cause... Nor is it anything that should be guessed at. Given the previous finding, this could be serious. You should immediately notify the neurologist of these and any other symptoms that may emerge as soon as possible. It's very important to the course of your treatment.

Today I guess you already got the diagnosis.I answer your post,is not want to give you the diagnosis,just want as reference for people read this post.Base on your complaints and the MRI finding it strongly pointing to the disease call MULTIPLE SCLEROSIS.As MERCK MANUAL SAY;"A SLOWLY PROGRESSIVE cns disease characterizes by disseminal patches of demyelination in brain and spinal cord,resulting in multiple and varied neurologic symptoms and signs,usually with remissions and exacerbations".The etiology is not clear,possible due to autoimmune,slow virus causes.The symptoms could be various from mental change,motor,sensory and autonomic changes.The course,prognosis is highly varied and the treatment also.

This is from August 2010 and the person asking has never been back.