What causes the symptoms of essential tremor?
The location of the abnormality in the brain that's creating the tremor is not yet well identified. When people have studied a central tremor, one does not find any kind of structural change in the brain. Using functional imaging, things like Positron emission tomography (PET) scans, which don't look at brain structure, but look at how the brain is working. There are certain locations within the brain that seem to be functioning abnormally. These are mostly located in a structure called the cerebellum, and also in the adjacent structure called the brain stem. But exactly how these things or abnormalities create the tremor is not well known. Another structure called the thalamus seems to play a role in essential tremor, because we know that if we injure the thalamus in some way, if we poke an electrode in there and zap it in some fashion, that the tremor will decrease or go away. But its not clear what this process is. There aren't any kind of brain chemistry abnormalities that have been identified with essential tremor as have been in, say, Parkinson's Disease.
