More commonly known as a prodrome, a prodromal is an early indication that some type of disease or illness is about to occur. Sometimes referred to as a pre-symptom symptom, prodromal signs are often very broad and can be an indicator of many different conditions. Often, these signs begin to manifest days or weeks before the actual onset of the ailment.
One classic example of prodromal symptoms has to do with an upcoming migraine headache. Several days prior to the actual development of the headache, someone may begin to experience an increase in general irritability. Periods of feeling sad may also take place, leading to a lack of interest in eating or any desire to participate in activities that normally provide pleasure.
Other health issues also manifest a prodromal phase. With herpes, an impending outbreak may be foreshadowed by a general sense of itching and burning in the area where the blisters will shortly appear. Some tingling may also take place in the same area. At first, these symptoms are hardly noticeable, but become increasingly obvious as the outbreak approaches.
People suffering with mental disorders such as some form of psychosis or panic disorder often begin to exhibit changes in perception well before an episode takes place. These changes may include a feeling of seeing certain objects in a different way, or reading things into the words uttered by the people around them. The individual may also find that his or her thoughts seem to stray into areas that are rarely of interest and remain mired in those areas for an inordinate amount of time.
People who suffer from epilepsy also experience a prodromal stage or phase. The period often begins with a vague sense of being uneasy or anxious about nothing in particular. There may be some general physical discomfort, such as tingling in the extremities or quick pains that seem to go away as quickly as they appear.
In some cases, these vague early signs disappear completely before the disease or ailment becomes manifest. At other times, they develop into full-blown symptoms that are indicative of a particular disease. The lack of consistency, coupled with the broad nature of the signs themselves, makes it very hard to diagnose an impending condition.
At present, there is no universal agreement on what causes the symptoms of prodromal stages to appear. One theory is that these early warning signs are due to a change in electrical activity in the brain, as the body prepares for the impending crisis. However, attempts to qualify this theory have lead to inconclusive results.