Sundowning isn't a disease itself. It is a description of how people with various types of dementia tend to perform worse as the day progresses towards evening.
789.0
Impingement syndrome ICD 9: 726.2
ICD-9 under syndrome, antiphospholipid antibody or anticardiolipin antibody 289.81
724.8
E24.9 - Cushing's syndrome, unspecified
ICD 9 CM Code - 338.29 Other chronic pain.
695.9
202.60
Myofascial pain syndrome (729.1)
Failed back syndrome is also referred to as postlaminectomy syndrome. The correct ICD-9 code for this would be 722.8, but there are also fifth-digit classifications depending on the region of the spine that is affected.
ICD-9 diagnosis code is 995.55
253.6
you can just use 307.5