Positive Symptoms During Spells
In the context of migraine with aura, positive symptoms include scintillations (visual phenomena like flashing lights) and pins-and-needles sensations, which are key diagnostic features that distinguish them from negative symptoms like visual loss or numbness. 1
Understanding Positive vs. Negative Symptoms
The distinction between positive and negative symptoms is clinically important for characterizing spells:
Positive Symptoms (Active Phenomena)
- Scintillations: Flashing lights, zigzag patterns, or other visual phenomena that represent active neurological activity 1
- Pins-and-needles sensations (paresthesias): Tingling or prickling sensations that indicate active sensory nerve firing 1
- Pulsating quality: In headache disorders, the throbbing or pulsating nature represents positive vascular activity 1
Negative Symptoms (Loss of Function)
- Visual field defects or blindness
- Numbness or loss of sensation
- Weakness or paralysis
- Loss of consciousness
Clinical Application in Spell Evaluation
When evaluating patients with spells, identifying positive symptoms helps narrow the differential diagnosis:
For Migraine with Aura
- At least one positive aura symptom is required for diagnosis according to International Classification of Headache Disorders criteria 1
- Positive symptoms typically spread gradually over ≥5 minutes and last 5-60 minutes 1
- The presence of positive symptoms (scintillations, paresthesias) helps distinguish migraine aura from other neurological events like transient ischemic attacks, which typically present with negative symptoms 1
For Syncope/Vasovagal Spells
- Prodromal positive symptoms include palpitations, warmth, nausea, and visual changes before loss of consciousness 1
- These warning symptoms allow patients to employ counter-pressure maneuvers (leg crossing, hand gripping, arm tensing) to abort the spell 1, 2
For Convulsive Syncope
- Myoclonic jerks (brief muscle contractions) represent positive motor phenomena that can occur during syncope 1
- However, these are typically few in number (versus 20-100 in generalized seizures) and lack the synchrony and rhythmicity of epileptic seizures 1
Common Pitfall
Do not assume that the presence of positive motor symptoms (myoclonus, jerking) automatically indicates epileptic seizures. Convulsive syncope commonly presents with myoclonic movements, but these differ in character, number, and synchrony from true epileptic activity 1. The key distinguishing features are the brief duration, lack of rhythmicity, and association with clear precipitating factors for syncope 1.