Syncope (sink oh pee) is defined as a transient loss of consciousness with spontaneous resolution. The terms that are used most often to describe syncope are fainting, blackouts or dizziness. Pre-syncope is the feeling of imminent loss of consciousness. It often precedes loss of consciousness, or may occur on its own without frank syncope.

Blackouts have a host of different causes, which may be anything from cardiovascular causes to neurological causes to psychiatric causes. The vast majority of episodes have cardiovascular causes. The most frequent diagnosis is vasovagal syncope. If you have received a diagnosis of vasovagal syncope from your doctor, please refer to the Vasovagal Syncope section.

A doctor determines the cause of blackouts after a clinical assessment in conjunction with preliminary testing in 50% of patients. An additional 30% of patients will be diagnosed after further testing. In at least 20% of patients, no cause is ever determined because blackouts resolve. Most patients with a single blackout will not have a recurrent blackout. Having said this, many patients are referred to a cardiologist because they have had more than one blackout.

Cardiac testing that is performed in blackout patients often includes an echocardiogram to assess the structure of the heart, as well as various monitoring tests to assess the rhythm of the heart. When vasovagal syncope is considered, a tilt table test may be performed.

The challenge in diagnosing patients with unexplained syncope stems from the fact that the cause has resolved by the time the patient presents for medical attention. For this reason, the heart's rhythm and the blood pressure and the brain's function is often restored to normal by the time these parameters are checked in the emergency room or in the physician's office. This leads to several forms of testing to try to assess the likelihood of recurrence, to set up a long term monitoring strategy to try to "capture" the next episode, or to provoke the symptoms with special testing.

The most frequently performed tests involve monitoring of the heart or brain to see whether ongoing abnormalities explain the syncope. These include a simple 12-lead EKG, a 24 or 48 hour Holter monitor, and an electroencephalogram (EEG). These monitor heart and brain function to look for evidence of heart slowing or racing, or abnormal brain function that could explain an arrhythmia or seizure.

Treatment of blackouts is dependent on the underlying cause. For patients with vasovagal syncope, lifestyle measures including increase in salt and water are often very successful. When an arrhythmia is diagnosed, treatment directed at the underlying cause is usually successful. For patients with heart slowing (bradycardia), a pacemaker is usually implanted. In patients with heart racing, medication is used or consideration of an ablation procedure or implantation of a defibrillator may be recommended. Finally, in patients with less frequent causes, treatment is delivered based on special circumstances. One example of this would be treatment for epilepsy in patients where seizure explains their blackouts.

A small percentage of patients with blackouts may have a life-threatening problem. It is important to be thoroughly evaluated by your doctor if you have had a blackout.

One of the most difficult situations surrounding blackouts is the impact on patients' lifestyles. This is particularly the case when it comes to impact on driving privileges. Driving privileges are governed by provincial or state law. It is important to be aware of the local laws and the impact on driving. In most Canadian jurisdictions, current law states that after an episode of loss of consciousness, driving should be suspended. The duration of the suspension varies from one week to one year, depending on the specific problem, the class of licence, and the likelihood of recurrence. If blackouts are recurrent, then driving restrictions become more stringent. In most Canadian jurisdictions, a physician is obliged by law to provide the Ministry of Transportation with a medical report on any patient who has a medical condition that could make it unsafe to drive. For this reason, many patients are frustrated because they feel betrayed by the medical system for reporting them. Similarly, physicians feel that this law influences the doctor/patient confidentiality relationship in a negative way. Having said that, physicians are obliged to be law abiding in their reporting of patients. Once a diagnosis is obtained, patients can apply for re-instatement of driving privileges. A letter from the family doctor accompanied by any specialist information is often requested by the Ministry of Transport to allow them to review the file and render the decision about resumption of driving privileges.