Consciousness relies on functioning of the brainstem and diffuse connections with the brain cortex. If a person loses this consciousness briefly we need to investigate whether this is an abnormality of blood flow resulting in low oxygen, a faint or syncopal attack, or a seizure.
Syncopal attacks tend to be shorter with less movement and more rapid recovery. In some there may be a simple “vasovagal” attack triggered by an unpleasant experience but if there are concerns I arrange investigations for more serious cardiac causes. These include structural abnormalities on an echocardiogram, abnormal cardiac rhythms or a tilt table test to look for unstable drops in blood pressure.
Seizures are caused by synchronous firing of nerve cells. Epilepsy is a tendency to recurrent seizures.
In some people these are generalised from the onset with tonic-clonic movements. In others there may be firing in particular parts of the brain causing focal motor or sensory dysfunction. In some cases discharges from the temporal lobes in particular can present with clouding of consciousness and unusual stereotyped behaviours.
Investigation relies on a thorough history looking for possible triggers and an accurate witness account. We investigate for brain abnormalities using a detailed MRI scan and for abnormal electrical discharges with an EEG usually done while the patient is asleep as it is more likely to capture abnormal brain activity.