Electrical Stimulation of the Brain

Definition

Electrical stimulation of the brain (ESB) is a relatively new technique used to treat chronic pain and tremors associated with Parkinson disease. ESB is administered by passing an electrical current through an electrode implanted in the brain.

Purpose

While the implantation of electrodes in the brain is used to treat or diagnose several disorders, the term ESB is limited here to the treatment of tremors, and as a pain management tool for patients suffering from back problems and other chronic injuries and illnesses.

Precautions

An ESB tremor control device, used in treating Parkinson patients, may interfere with or be affected by cardiac pacemakers and other medical equipment. As a result, patients with other implanted medical equipment may not be good candidates for the therapy.

Description

Electrical stimulation of the brain, or deep brain stimulation, is effective in treating tremor in up to 88% of Parkinson disease patients. An electrode is implanted into the thalamus (part of the brain) of the patient, and attached to an electric pulse generator via an extension wire. The pulse generator is implanted into the patient's pectoral, or chest area, and the extension wire is tunneled under the skin. The pulse generator sends out intermittent electrical stimulation to the electrode in the thalamus, which inhibits or partially relieves the tremor. The generator can be turned on and off with a magnet, and needs to be replaced every three to five years.

Similar methods have been used to treat chronic pain that responded unfavorably to conventional therapies. A remote transmitter allows these patients to trigger electric stimulation to relieve their symptoms on an as-needed basis. Patients with failed back syndrome, trigeminal neuropathy (pertaining to the fifth cranial nerve), and peripheral neuropathy fared well for pain control with this treatment, while patients with spinal cord injury and postherpetic neuralagia (pain along the nerves following herpes) did poorly.

Preparation

The patient should be free of any type of infection before undergoing an ESB procedure. He or she may be advised to discontinue any medication for a prescribed period of time before surgery.

Aftercare

After neurosurgery, patients should undergo regular head dressing changes, minimize exposure to others, and practice good personal hygiene in order to prevent a brain infection. The head may also be kept elevated for a prescribed period of time in order to decrease swelling of the brain.

Risks

The implantation of electrodes into the brain carries risks of hemorrhage, infarction, infection, and cerebral edema. These complications could cause irreversible neurological damage.

Patients with an implanted ESB tremor control device may experience headaches, disequilibrium (a disturbance of the sense of balance), burning or tingling of the skin, or partial paralysis.

Normal results

ESB is effective in pain control for specific conditions. It can provide long-term pain relief with few side effects or complications.

For the control of tremors a deep brain stimulator does provide some relief. It is recommended for patients with tremors severe enough to affect their quality of life.

Resources

OTHER

The Parkinson's Web. 〈http://pdweb.mgh.harvard.edu〉.

University of Southern California. The ANGELN eurosurgical Information Resource. 〈http://www.usc.edu/hsc/neurosurgery/angel.html〉.

KEY TERMS

Infarction— A sudden insuffiency of local blood supply.

Neuralgia— Pain extending along one or more nerves.

Neuropathy— A functional disturbance or change in the nervous system.

Parkinson disease— A chronic neurological illness that causes tremors, stiffness, and difficulty in moving and walking.

Electrical stimulation of the brain (ESB)

A procedure which involves the introduction of a weak electrical current into specific locations in the brain by using multiple microelectrodes to apply short pulses of electrical currents intended to mimic the natural flow of impulses through the neural pathways.

Electrical stimulation of the brain (ESB) is useful in a variety of situations, including neurosurgical operations and experimental research. In neurosurgery, this procedure may be used to assist physicians in determining which brain tissue should be removed. Because the patient must remain awake during the procedure, only a local anesthetic is administered. Focal epilepsy has been surgically treated by using electrical brain stimulation in conscious patients to determine the epileptic focus.

In experimental research, ESB does not control complex behavior patterns such as depression , but it can be employed quite successfully to control individual functions. Therefore, this procedure has proven useful in studying the relationships among various areas and structures of the brain and the activities they control. It has been found, for example, that stimulation of the visual cortex produces visual sensations, such as bursts of light or color (blind people have seen spots of light as a result of ESB). Similarly, stimulation of the auditory cortex results in aural sensation, while stimulating areas associated with motor control produces arm, leg, or other body movements. Stimulation of areas of the brain linked to association can induce memories of scenes or events.

In addition to research and experimental uses, electrical brain stimulation has been successfully used for some therapeutic purposes. Brain stem and cerebellar stimulation have aided in some movement disorders; peroneal nerve stimulation has been used to treat dropfoot in stroke victims; and transcutaneous nerve, dorsalcolumn, and deep-brain stimulation have proven useful in the relief of chronic severe pain .

Electrical brain stimulation has aided in mapping connections between different regions of the brain in animals, and has been used to induce many different types of behavior in animals, including eating, drinking, aggression , hoarding, and both sexual and maternal behavior. While hypothalamic stimulation is associated with such emotional responses as attack and defense, stimulation of the reticular formation in the brain stem can induce sleep . ESB has also confirmed the existence of a "reward center" in animals, whereby animals can be taught to stimulate their own brains mechanically by pressing a lever when such stimulation results in a pleasant sensation.