What is an aura in the context of neurological events?

What is an Aura in Neurological Events?

An aura is a fully reversible focal neurological symptom that develops gradually over at least 5 minutes, typically lasts 5-60 minutes, and usually precedes or accompanies a neurological event such as migraine or seizure. 1

Core Defining Characteristics

Auras are distinguished by four key features that differentiate them from other acute neurological events:

• Gradual onset and spread: Aura symptoms characteristically spread gradually over ≥5 minutes, rather than appearing suddenly and simultaneously 1, 2
• Sequential progression: When multiple aura symptoms occur, they typically follow one another in succession rather than all at once 1
• Time-limited duration: Each individual aura symptom lasts 5-60 minutes (though motor symptoms in hemiplegic migraine may persist up to 72 hours) 1
• Complete reversibility: All aura symptoms are fully reversible with no permanent neurological deficit 1, 3

Types of Aura Symptoms

Visual Aura (Most Common)

Visual aura occurs in over 90% of patients who experience aura, making it by far the most prevalent manifestation: 1, 3

• Positive phenomena: Scintillations (flashing lights), fortification spectra (zigzag lines), bright dots, or shimmering effects described as "looking through heat waves or water" 1, 2, 4
• Negative phenomena: Scotoma (blind spots), "foggy" vision, tunnel vision, or blurred vision 5, 4
• Visual auras typically begin as a slowly expanding spot of light that gradually spreads across the visual field 6

Sensory Aura

Sensory symptoms occur in approximately 31-36% of patients with aura: 1, 3, 7

• Predominantly unilateral paresthesia (pins and needles) and/or numbness that spreads gradually, most commonly affecting the face or arm 1
• The gradual spreading pattern is a critical distinguishing feature from stroke or TIA 1

Speech and Language Aura

Aphasic speech disturbances occur in approximately 14% of patients with aura: 1, 7

• Aphasia is always considered a unilateral symptom, while dysarthria may or may not be unilateral 1
• These symptoms are less common than visual or sensory manifestations 1

Less Common Aura Types

Additional aura manifestations include: 1

• Motor aura: Weakness (seen in hemiplegic migraine), which may last longer than other aura types 1
• Brainstem aura: Dysarthria, vertigo, or other brainstem symptoms 1
• Retinal aura: Repeated monocular visual disturbances 1

Aura in Different Neurological Conditions

Migraine with Aura

Approximately one-third of individuals with migraine experience aura, either with every attack or intermittently: 1, 3

• The aura is typically accompanied by or followed by headache within 60 minutes 1
• Many individuals experience both migraine attacks with aura and attacks without aura, and both diagnoses should be made when this pattern occurs 1
• At least two attacks fulfilling aura criteria are required for diagnosis 1

Epileptic Aura

In epilepsy, aura refers to abnormal sensations occurring in the pre-ictal phase before seizure onset: 1, 2

• Epigastric aura: A rising sensation from the abdomen is common in temporal lobe epilepsy and is relatively rare in other conditions 1, 2
• Experiential aura: Déjà vu or jamais vu experiences associated with temporal lobe epilepsy 2
• Sensory aura: May include unpleasant smells or tastes, auditory hallucinations ranging from buzzing to complex sounds like music 2
• Epileptic auras provide important lateralizing and localizing information for presurgical assessment 2

Paroxysmal Kinesigenic Dyskinesia

In PKD, aura manifests as abnormal sensations prior to involuntary movements: 1

• Approximately 78-82% of PKD patients experience aura, most commonly described as numbness, tingling, or muscle weakness 1
• Some patients can abort dyskinesia attacks by slowing movements when experiencing aura 1
• Aura may occasionally appear in isolation without subsequent dyskinesia 1

Critical Differential Diagnosis

The gradual onset and spreading pattern of aura is the key feature distinguishing it from transient ischemic attacks (TIA): 1

• Aura: Symptoms spread gradually over ≥5 minutes and occur in succession 1
• TIA: Symptoms have sudden, simultaneous onset affecting a vascular territory 1, 3
• When a patient presents with first-time possible aura without visual symptoms, or with simultaneous neurological symptoms corresponding to a cerebral vascular territory, emergency exploration for TIA is necessary 3

Red flags requiring urgent evaluation include: 3

• Aura duration greater than one hour (excluding motor symptoms)
• Late onset of aura (new onset in older adults)
• Dramatic increase in frequency of aura attacks
• Absence of gradual onset or spreading pattern

Clinical Significance and Prognosis

Aura carries important clinical implications beyond symptom recognition: 3

• The relative risk of ischemic stroke is significantly increased in migraine with aura 3
• Combined hormonal contraception with estrogens significantly increases stroke risk in women with migraine with aura and should be avoided 3
• Aura symptoms provide diagnostic and localizing information that guides both acute and preventive treatment strategies 2