It has been reported that some patients have been misdiagnosed with Essential Tremor, when in fact the correct diagnosis in their specific case was Parkinson's Disease.
Parkinson’s disease is a progressive nervous system disorder that affects movement usually starting with a hand tremor. Symptoms include slowed movement, rigid muscles, impaired posture and balance, loss of automatic movements, and speech and writing changes. It can be misdiagnosed as conditions such as essential tremors, normal pressure hydrocephalus, dementia with Lewy bodies, multiple system atrophy, corticobasal syndrome, and progressive supranuclear palsy.