Syncope, Seizures, and Their Mimics



Syncope, Seizures, and Their Mimics





Syncope


Definition

Transient alteration of consciousness and loss of muscular tone due to acute, reversible global reduction in cerebral blood flow. Most common cause of loss of consciousness.



  • History: precipitating stimulus (heat, psychological stress), nature of fall (limp or swoon without injury); autonomic prodromal symptoms (light-headedness, sweating, palpitation, apprehension, feeling of impending faint).


  • Differences from most seizures: rhythmic movements, urinary incontinence rare; recovery within seconds of lying down; no post-ictal symptoms (headache, confusion, lethargy).

Few clonic jerks of arms and legs may occur (convulsive syncope).

Features: See Table 3.1.








Table 3.1 Syncope VS. Seizure: Useful Distinguishing Features












































































  Syncope Seizure
Before Spell    
Trigger (position, emotion, Valsalva) Common Rare
Sweating & nausea Common Rare
Aura (e.g., déjà vu, smell) or unilateral symptoms Rare Common
During Spell (From Eyewitness)    
Pallor Common Rare
Cyanosis Rare Common
Duration of LOC <20 secs >60 secs
Movements A few clonic or myoclonic jerks; brief tonic posturing (few secs); duration <15 secs; always begin after LOC Prolonged tonic phase, then prolonged rhythmic clonic movements; duration >1 min; may begin at onset of LOC or before; unilateral jerking (partial seizure)
Automatisms Occasional Common (in complex partial and secondarily generalized seizures)
Tongue biting, lateral Rare Occasional
Frothing/hypersalivation Rare Common
After Spell    
Confusion/disorientation Rare; <30 secs Common; several mins or longer
Diffuse myalgias Rare, brief, usually shoulders/chest Common, hours–days
CK elevation Rare Common (especially after 12 to 24 hours)
Features That are Not Helpful for Differentiating Incontinence, prolactin level, dizziness, fear, injury other than lateral tongue biting, eye movements (rolling back), brief automatisms, vocalizations, visual or auditory hallucinations Incontinence, prolactin level, dizziness, fear, injury other than lateral tongue biting, eye movements (rolling back), brief automatisms, vocalizations, visual or auditory hallucinations
CK, creatine kinase; LOC, loss of consciousness; min, minute; sec, second.


Neurocardiogenic Syncope



  • Mechanism: direct cardiac inhibition.


  • Features: adolescents, young adults. Usually seated or standing, not supine. Autonomic symptoms before spell. Bradycardia during spell.

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Jul 27, 2016 | Posted by in NEUROLOGY | Comments Off on Syncope, Seizures, and Their Mimics

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