Essential tremor is a very common but complex movement disorder. In most people, essential tremor is mild and can be controlled by medication. For some, however, the tremor is so severe that it causes disability or significantly impacts quality of life and cannot be adequately controlled by drug therapy. Thalamotomy, in which a portion of the thalamus deep within the brain is destroyed, was the neurosurgery of choice for essential tremor until the advent of deep brain stimulation and is still used today under certain circumstances. Most often when a thalamotomy is performed today, however, it will be done using stereotactic radiosurgery (see below). The essential tremor patient electing to have deep brain stimulation surgery usually experiences significant tremor relief. The usual target in the brain for deep brain stimulation for treatment of symptoms of essential tremor is the ventral intermediate nucleus (ViM) of the thalamus.