hi welcome to healthcaremagic. Degeneration of cerebellum is the main cause of balance detioration so it is not surprising that he is facing difficulty in walking. Degeneration of cerebellum and cerebrum is a slow atrophy or shrinking of the brain, the reason of which is not exactly know but genetic predisposition is seen and is seen in families. Important measure which helps in cerebellar atrophy is physiotherapy which should be done daily for 1hr. You meet a good neurologist who will prescribe some antioxidants which will halt or arrest the progress of the disease along with cerebellar coordination exercises.