chronic denervation of the nerve is loss of myelin covering of the nerves which helps in conduction of impulse along the nerves. there are various reasons both acute and chronic. Acute is injury to the nerve and the most common chronic cause is nutritional and destruction of nerve due to pressure over the nerve root
seen in spondylosis
and chronic disease like diabetes
and inflammatory lesions like leprosy
,polio. so we have to find the cause of denervation in your case and treat it accordingly.