Differentials
Aromatic L-amino acid decarboxylase deficiency
Autonomic dysreflexia syndrome in spinal injuries.
Dopamine beta-hydroxylase deficiency
Multiple System Atrophy
Parkinson Disease
Parkinson-Plus Syndromes
Progressive Supranuclear Palsy
Pure Autonomic Failure
Surgical sympathectomy
Syphilis (tabes dorsalis)
Vagotomy
http://emedicine.medscape.com/article/1173756-differential