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Micturition syncope is one of several varieties of situational fainting, during which the victim temporarily loses consciousness during or immediately after urination. The condition occurs more frequently in males than females, with a peak age of onset between 30 and 50. Physicians believe that the process of straining to urinate stimulates a circulatory reflex of the vagus nerve, producing a substantial slowing of the heart rhythm and a precipitous drop in blood pressure associated with pooling of blood in the lower extremities. This results in decreased blood flow and oxygenation in the brain, which produces a loss of consciousness. Associated symptoms of micturition syncope include preceding dizziness, clamminess, nausea, stomach pain, and fading of the vision.
Episodes of this type of fainting typically occur when the patient has just arisen from lying down for a prolonged period, such as in the morning or late evening. Drinking too much alcohol, having a fever, or being too hot also increase the frequency of micturition syncope. Other contributing factors of situational fainting include emotional stress or shock, pain, anemia or mild blood loss, poor physical condition, and low blood sugar levels. Micturition syncope accounts for about four to eight percent of all syncope or fainting cases. It is not life threatening and occurs only intermittently.
Some cases of micturition syncope may be accompanied by a few limb jerks, similar to those seen with seizures. There is usually no tongue biting, incontinence, or post-episode confusion, however. The greatest health risks of micturition syncope are lacerations or contusions suffered during a fall, which may include severe head injuries. When discovered, the patient should be allowed to rest on the floor until consciousness returns, and ammonia inhalants and cold water should not be used to revive the patient. Complete recovery occurs within a few seconds to minutes of the micturition syncope, with the patient remembering the events just before the episode.
Urination, defecation, vomiting, swallowing cold beverages, and severe coughing may all cause situational syncope. All of these activities activate mechanisms in the body that lower the blood pressure. Although most cases of situational syncope are harmless and self-limited, medical evaluation for associated diseases is essential, especially in elderly patients. For example, some cases of micturition syncope may be associated with prostate enlargement either from prostatic hypertrophy or prostate cancer. Furthermore, more than one-third of defecation syncope patients die from related, underlying diseases within two years of onset of the syncope.
After evaluation for underlying diseases, most cases of mild micturition syncope do not require treatment. Patients should sit on the side of the bed for several minutes before arising to go into the bathroom, if possible. Additionally, the patient may avoid the fainting attack if he sits down during urination. If the episodes are severe, physicians may treat patients with beta-blocking medications or some forms of antidepressant medication. Furthermore, patients with a pre-existing abnormally slow heart beat, called bradycardia, may benefit from cardiac pacemaker placement.