No such blockage is found in patients with Normal Pressure Hydrocephalus. There is no known cause of Normal Pressure Hydrocephalus. Usually patients do not have tremor and cannot be distinguished from patients with PD on the basis of a neurological exam. Patients with Striato-Nigral Degeneration however do not respond to Levadopa. Only after death can this disorder be distnguished from PD because in Striato-Nigral Degeneration most of the damage is in the Striatum and not the Substantia Nigra.
Arteriosclerosis is especially likely to occur in patients with high blood pressure or diabetes.
The two disorders may not be distinguished on the basis of a neurological examination alone. Patients with Pseudobulbar Palsy do not respond to antiparkinsonian drugs. Progressive Supernuclear Palsy - An uncommon disorder in which patients develop Paralysis of theeir eye movements, difficulty in speaking, rigidity, and senility. This disorder causes changes in the brain that are similar to those of PD, but are even more extensive. Patients with this condition do not respond to antiparkinson drugs.