Administration of ECT
ECT is performed while the patient is unconscious. Unconsciousness is induced by a short-acting barbiturate such as methohexital (Brevital sodium), or another appropriate anesthetic drug. The drug is given intravenously. To prevent the patient from harming themselves during the convulsions or seizures induced by ECT, he or she is given succinylcholine (Anectine) or a similar drug that temporarily paralyzes the muscles. Because the patient’s muscles are relaxed, the seizures will not produce any violent contractions of the limbs and torso. Instead, the patient lies quietly on the operating table. One of the patient’s hands or feet, however, is tied off with a tourniquet before the muscle relaxant is given. The tourniquet prevents the muscles in this limb from being paralyzed like the muscles in other parts of the patient’s body. The hand or foot is used to monitor muscle movement induced by the electrical current applied to the brain.
A breathing tube is then inserted into the unconscious patient’s airway and a rubber mouthpiece is inserted into the mouth to prevent him or her from biting down on teeth or tongue during the electrically induced convulsion. As the current is applied, brain activity is monitored using electroencephalography. These brain wave tracings tell the medical team exactly how long the seizure lasts. The contraction of muscles in the arm or leg not affected by the muscle relaxant also provides an indication of the seizure’s duration.
The electrodes for ECT may be placed on both sides of the head (bilateral) or one side (unilateral). Physicians often use bilateral electrode placement during the first week or so of treatments. An electric current is passed through the brain by means of a machine specifically designed for this purpose. The usual dose of electricity is 70-150 volts for 0.1-0.5 seconds. In the first stage of the seizure (tonic phase), the muscles in the body that have not been paralyzed by medication contract for a period of 5-15 seconds. This is followed by the second stage of the seizure (clonic phase) that is characterized by twitching movements, usually visible only in the toes or in a nonparalyzed arm or leg. These are caused by alternating contraction and relaxation of these same muscles. This stage lasts approximately 10-60 seconds. The physician in charge will try to induce a seizure that lasts between one-half and two minutes. If the first application of electricity fails to produce a seizure lasting at least 25 seconds, another attempt is made 60 seconds later. The session is stopped if the patient has no seizures after three attempts. The entire procedure, from beginning to end, lasts about 30 minutes.
The absence of seizures is most commonly caused either by the patient’s physical condition at the time of treatment or by the individual nature of human responses to drugs and other treatment procedures. Just as there are some patients who do not respond to one type of antidepressant medication but do respond to others, some patients do not respond to ECT.
The total number of ECT treatments that will be given depends on such factors as the patient’s age, diagnosis, the history of illness, family support and response to therapy. Treatments are normally given every other day with a total of two to three per week. The ECT treatments are stopped when the patient’s psychiatric symptoms show significant signs of improvement. Depending on the patient’s condition, this improvement may happen in a few weeks or, rarely, over a six-month period. In most cases, patients with depression require between six and twelve ECT sessions.
Only rarely is ECT treatment extended beyond six months. In such infrequent cases, treatments are decreased from two to four per week after the first month to one treatment every month or so.
No one knows for certain why ECT is effective. Because the treatment involves passing an electric current through the brain, which is electrically excitable tissue, it is not surprising that ECT has been shown to affect many neurotransmitter systems. Neurotransmitters are chemical messengers in the nervous system that carry signals from nerve cell to nerve cell. The neurotransmitters affected by ECT include dopamine, norepinephrine, serotonin and GABA (gamma-aminobutyric acid).
This woman has been prepared to receive electroconvulsive therapy- an effective treatment for depression. This patient has been given a short-acting medication that induces unconsciousness, and another medication was given that relaxes her muscles so that the induced seizures will not produce any violent contractions. Instead, the patient lies quietly on the operating table. The rubber mouthpiece keeps her from biting down on teeth or her tongue during the seizure.