This topic addresses a patient who says they โpassed out,โ or had amnesia for a period of time, usually somewhat recently, but now they feel and look completely fine. Exam is normal. We have possible causes to sort through (see table below). For patients with Memory Loss, see that topic.
For the E.R. diagnostic work-up of a patient actively in coma, seizing, or highly confused, see the mnemonic “Vowel TIPS”.
Causes of Loss of Consciousness (LOC)
| …………..Patient Fell to Floor โข Faint (a.k.a. Syncope) โข Seizure (generalized, “Grand Mal”) โข Transient Ischemic Attack (TIA) โข Concussion (from Head Trauma) โข Conversion Reaction โข Hyperventilation โข Intoxication | ……….Episode of Amnesia (without Fall) โข Complex-Partial Seizure โข Dissociative State โข Transient Global Amnesia โข Intoxication x x |
Brief Definitions of the Diseases (see links for more explanation)
Faint: Sudden momentary drop of blood circulation to the brain. Several kinds:
….. โข Vasovagal (due to emotions, certain body functions, hot room, etc.; may feel nausea / woozy)
….. โข Orthostatic (standing up too fast if dehydrated, on certain meds, have certain diseases)
….. โข Cardiac Arrhythmia
….. โข Other Heart Diseases (Coronary Artery Disease; Obstruction of Blood Flow out of Heart)
.…. โข Occurs with Turning Head (very rare)
Seizure (generalized): Nerve transmission in brain goes haywire; massive short circuits
Transient Ischemic Attack (TIA): Start of a stroke, that resolves quickly on its own
Conversion Reaction: Psychological way for mind to escape intolerable situation
Hyperventilation: Very fast breathing from Anxiety
Complex-Partial Seizure: Unconscious weird behavior; short-circuit in one lobe of brain
Dissociative State: Mind is so distracted (often traumatic memories), acts without awareness
Transient Global Amnesia: Canโt retain new memories, like where they are, what theyโre doing
Intoxication: Alcohol; any substances; poisoning
We make the diagnosis 100% by the medical history. Witnesses give crucial clues; unwitnessed LOC is much harder. Our most likely diagnoses for someone who has passed out or lost consciousness are:
- Fell to Floor: Faint vs. Seizure (Generalized) vs. Conversion Reaction
- If Faint: Is it possibly Dangerous (Heart Diseases) or Not (Vasovagal / Orthostatic)
- No Fall (witnessed): Seizure (Complex-Partial) vs. Transient Global Amnesia
- No Fall (unwitnessed): Seizure (complex partial) vs. Dissociative State
KEY CLUES (we query witnesses if any, or glean as best we can):
Fell to (or Awoke on) the Floor
Duration of LOC on Floor:
- <20 secs: Faint
- >1 min: Seizure
- >5 min: Conversion Reaction
Recovery:
- Rapid: Faint; Conversion Reaction
- Gradual transition from confused to aware (10-30 min): Seizure
Patient Can Recall What Others Around Did During the Episode: Conversion Reaction
Movements of Arms & Legs:
- Stiff & Shaking: Seizure (can occasionally occur briefly with simple Faint)
- Flailing (random): Conversion Reaction
Eyes:
- Rolled back: Seizure; Faint
- Rapidly shake in one direction (aka โnystagmusโ): Seizure
- Glazed: Faint; Seizure
- Clenched Shut: Conversion Reaction
Biting:
- Sides of Tongue: Seizure; maybe Faint
- Tip of Tongue, Lips, hands, etc.: Conversion Reaction
Triggers That Provoked the Event:
- Environmental (ugly sight, smell, etc); Straining; Emotions: Faint
- Exertion: Faint from Heart Disease
- Confrontational or Situational Stress: Conversion Reaction
- Neck Movement (rare): Faint; TIA (very rare)
Atherosclerosis (Heart Risks: old age, smoking, hypertension, diabetes, etc; see link)
- Faint from Arrhythmia or Coronary Artery Disease
- Transient Ischemic Attack (TIA) (basilar artery territory of brain)
- Seizure (always possible anyway)
Symptoms Just Before Collapse:
- Aura (vague sensations like smell, flashing lights, etc.): Seizure
- Vertigo, Double Vision, Slurred Speech, Swallowing difficulty: TIA
Face Turned Blue / Foamed at Mouth / Incontinence: Seizure
No Fall, but Loss of Awareness (Witnessed)
Strange Movements or Actions: Complex-Partial Seizure
- grimace, lip-smack, chew, teeth clench, drool, swallow, blink
- twitch shake, foot stomp, hand wave, tremor
- stare, stiffen up
- randomly walks around / runs / undresses
- utters meaningless sounds
Patient Recall
- Total amnesia of the episode: Complex-Partial Seizure
- Total loss of awareness during the episode: Complex-Partial Seizure
- Knew his/her name during the episode: Transient Global Amnesia
- Retained past memories during the episode: Transient Global Amnesia
No Fall, episode of Amnesia (Unwitnessed):
We do tests to distinguish Complex-Partial Seizure vs. Dissociative State
- Total Global Amnesia possible (if lasted 1-10 hours)
- Intoxication possible
- Can be impossible to distinguish
DIAGNOSTIC WORK-UP
Tests we order depend on the reason we think a person passed out:
1. If we suspect Faint (a.k.a. Syncope):
- History suggests Vasovagal or Orthostatic Syncope โ no tests
- Faint during Exertion โ EKG, Echocardiogram, maybe Stress Tests
- Simply Faints โ EKG
- Recurrent Faints โ Ambulatory / Implantable EKG monitor
- Cardiac Referral if EKG abnormal
- Faints repeatedly when turns head a certain way (very rare)
- Angiogram by MRI or CT; then Refer to Vascular Specialist
- We send to ER if:
- Same-day Faint with exertion
- Same-day Faint + abnormal EKG or risks for Heart Disease
2. If we suspect Seizure (any kind):
- MRI
- Electroencephalogram (EEG), best if done while sleep-deprived
- Refer to Neurology
3. If we suspect basilar artery Transient Ischemic Attack (TIA) [rare)]
- MRI of brain
- MR- / CT-Angiogram of both Head and of Neck
4. If we suspect a Conversion Reaction โ no tests
- We reassure patient it is a common psychological defense mechanism
- If patient / family insist on โtestsโ โ Refer to Neurology to decide
5. If unwitnessed episode of Amnesia without a Fall
- We canโt distinguish Complex-Partial Seizure vs. Dissociative State by history
- We order MRI, EEG, and Refer to Neurology
See Passing Out โ Full Text for more in-depth explanations and discussions.