The three main types of loss of consciousness episodes are syncope (i.e. fainting, very frequent and usually benign), epileptic seizures and psychogenic non-epileptic seizures. It is very important to identify the type of consciousness disturbance episodes and, if possible, their etiology, before attempting any treatment. Proper consideration of history, clinical examination, and readily available ancillary tests allows for the correct diagnosis of the type of episodes in the vast majority of cases.Caution is needed for the possibility of different types of episodes coexisting in the same patient.
SYNCOPAL EPISODES (FAINTING)
They are due to reduced blood supply, or less frequently, reduced oxygenation or glucose supply to the brain.
Decreased cerebral blood supply is usually due either to orthostatic hypotension (inadequate activation of the Sympathetic Nervous System), to idiosyncratic vasovagal activation (excessive activation of the Parasympathetic Nervous System), or a combination of both. The most common triggering events, alone or in combination, are: standing up, taking antihypertensive medications (but sometimes other medication types), overheating, overcrowding, physical exhaustion, neck pressure (e.g. narrow collar), sight or even the thought of medical actions or conditions (such as the sight of blood), effort to defecate and emotional stress.
Orthostatic and vasovagal episodes are usually diagnosed by careful medical history by any physician, are benign and do not require extensive diagnostic testing. However, specialized investigations may be required in cases of atypical symptomatology or diagnostic doubts.
Rare but generally dangerous are fainting episodes due to cardiac pathology (heart arrhythmia, coronary heart disease, heart failure). Suspicion of cardiogenic syncope requires a cardiac evaluation.
EPILEPTIC SEIZURES
There are many types of seizures. Some of them manifest with a disturbance of consciousness with or without convulsions. Atypical or subtle seizure symptomatology may cause diagnostic confusion with fainting or psychogenic episodes. Suspicion of epileptic nature of the episodes is an indication for neurological assessment.
PSYCHOGENIC NON-EPILEPTIC SEIZURES (PNES)
Usually a detailed history reveals psychiatric comorbidity and episode phenomenology incompatible with seizures or fainting episodes. However, epileptic seizures and PNES sometimes coexist in the same patient. In fact, patients with epilepsy are more likely to have PNES in addition to epileptic ones.