Deep brain stimulation was approved by the Food and Drug Administration for the treatment of essential tremor in 1997. It was later expanded to treat Parkinson's disease in 2002, and dystonia in 2003. It can be approved on a case by case basis to treat obsessive-compulsive disorder.
Up until the 1950s, the only treatment for Parkinson's disease was using surgery to lesion parts of the corticospinal pathway or the basal ganglia structures in the brain that were affected. By destroying the specific parts of the brain that were being affected by the disease, the symptoms often improved. However, this was not ideal, because the surgery was permanent, and while it treated the positive symptoms of Parkinson's disease (tremor and rigidity), the negative symptoms remained (difficulty with postural fixation and akinesia).
In the 1970's a drug called levodopa was discovered. In Parkinson's disease, the part of the brain called the substantia nigra is not producing the neurotransmitter dopamine. Levodopa can be taken by patients, and it is converted into dopamine in the brain, bringing relief. The drug brought relief to many patients, but it was not without side effects.
In the 1980's it was discovered that by stimulating with electricity the same regions of the brain that used to be lesioned, similar effects could be achieved. The procedure is now used to help patients whose symptoms cannot be treated with medications or patients who have had severe side effects to medication.