Brief Answer: needs workup, Too early to point etiology Detailed Answer: hello there! Thank you for asking, I read your query and i want you to know that withered left arms need alot of work up like MR scans, neural assessments, EMGs etc with a detailed history and physical exams as many etiologies can be responsible for it. Spinal calamities, cervical vertebral issues, brachial plexus injuries, Some palsies like Erbs etc .some vasculopathy like churg strauss, Age related degenerative arthalgias , geriatric neuropathies, nutriotional neurppathies. So i believe you need work up and a team of neurologist, rheumatologist and a geriatric specialist to sort out the etiology for you. A one sentence of withered arm complaint would not be enough any humanly way. Right now with this much info it is no more than XXXXXXX hardy's storybook " Withered Arm". Consult them all and seek their help and do as they direct you to. I wish you good luck and No worries , if 16 months have been innocuous they wont do any harm in near future but is good to know the reason. if you have any more queries, please feel free to ask , i would be happy to answer. Other wise kindly close the discussion and rate the answer as per your experience. Regards S Khan

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