In reality none of the seizures actually cause this
Generalized tonic–clonic seizures have obvious motor manifestations
myoclonic seizures are very short jerks with no detectable LOC
atonic seizures may cause abrupt falls but no prolonged LOC
complex partial seizures or absence seizures cause alterationof awareness butnot limp motionless LOC.
Episodes of LOC with eyes closed for several seconds to minutes are either psychogenic or syncopal
However, confusion arises as syncopal events can appear "convulsive"
they in fact frequently involve brief body jerks.
Motor symptoms associated with syncope are clonic- or myoclonic-like,
tend to last only a few seconds, and terminate once the patient is horizontal, in sharp contrast
to the typical generalized tonic–clonic seizure duration of 30 to 90 seconds
Most common mechanism for syncope (vasovagal response)
typically triggered by clear precipitants (e.g., pain such as inflicted
by medical procedures, emotions, cough, micturition, hot environment,
prolonged standing, exercise)
Other historical features that favor syncope
presyncopal prodromes (malaise, sweating, dizziness, lightheadedness, nausea, chest pain, palpitations), as well
as age and a history of cardiovascular disease.
Historical features that favor seizures
tongue biting, head turning, posturing, urinary incontinence,
cyanosis, prodromal déjà-vu, and postictal confusion
Point based score system [94% sensitivity and 94% specificity]link
EEGs are sensitive to decreased cerebral blood flow -> by the time LOC occurs -> EEG changes are present -> delta slowing and suppression
seizure may present with loss of awareness as the sole reported feature
Typical absences involve arrest of activity, reduced or lost awareness, eyelid blinking or twitching, and sometimes small myoclonic facial or limb jerks, or brief facial automatisms such as lip smacking or chewing. Often occur many times per day. There may also be isolated myoclonic jerks.
Atonic seizures usually give rise to drop attacks but may appear to cause blank spells if the patient is sat or laying down and so cannot fall.
Complex partial seizures may cause loss of awareness with few if any other features.
Chronic daytime sleepiness with episodic sleep attacks; also cataplexy, sleep paralysis, hypnagogic and hypnopompic hallucinations. more
Intense fear with palpitations, diaphoresis, choking sensation, shortness of breath, chest pain, nausea, dizziness, derealization, fear of dying/losing control, parasthesias, chills. Occasionally these preludes may be forgotten, and attacks present with loss of awareness. more
Rare except in patients for treated diabetes mellitus; very rare insulin secreting tumor; history of a missed meal prior to the attack. more
Head injury -> LOC and / or amnesia. Occasionally, structural CNS abnormalities may present with episodes of loss of awareness.more
Isolated episodes of loss of awareness may also be caused by abuse of psychotropic drugs or other substances.