What is an aura?

What is an Aura?

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, 2

Core Defining Characteristics

Auras are distinguished by four essential features that separate them from other acute neurological events 2:

• Gradual onset and spread occurring over ≥5 minutes, rather than sudden simultaneous appearance 1, 2
• Sequential progression where symptoms follow one another in succession rather than all at once 1, 2
• Time-limited duration with each individual symptom lasting 5-60 minutes (though motor symptoms may persist up to 72 hours) 1, 2
• Complete reversibility with no permanent neurological deficit 1, 2

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 2, 3, 4. Characteristic features include:

• Positive phenomena such as scintillations (flickering lights), fortification spectra (zig-zag lines), bright dots, or shimmering effects 1, 2, 4
• Typical progression starting as a flickering, uncolored zig-zag line in the center of the visual field, gradually progressing toward the periphery of one hemifield 4
• Often leaves a scotoma (blind spot) in its wake 4

Sensory Aura

Sensory symptoms occur in approximately 31-36% of patients with aura 2, 4. Features include:

• Predominantly unilateral paresthesia and/or numbness that spreads gradually 1, 2
• Typical progression starting in the hand, moving toward the arm, then affecting the face and tongue 4
• Characterized by pins and needles sensations (positive symptoms) 1

Speech and Language Aura

Aphasic disturbances occur in approximately 14-18% of patients with aura 2, 4. Key points:

• Aphasia is always regarded as a unilateral symptom 1
• Dysarthria may or may not be unilateral 1

Motor, Brainstem, and Retinal Aura

These are less common manifestations 1, 2:

• Motor aura occurs in only 6% of patients and is half-sided, typically affecting the hand and arm 4
• Motor symptoms may last up to 72 hours, unlike other aura types 1

Aura in Different Clinical Contexts

Migraine with Aura

Approximately one-third of individuals with migraine experience aura 2, 3. Critical features:

• The aura is typically accompanied by or followed by headache within 60 minutes 1
• At least 2 attacks are required for diagnosis 1
• Headache follows the aura in 93% of cases, occurs simultaneously in 4%, and aura follows headache in 3% 4

Epileptic Aura

In epilepsy, aura refers to abnormal sensations occurring in the pre-ictal phase before seizure onset 5, 2. Distinguishing features:

• Rising sensation from abdomen (epigastric aura) is common in temporal lobe epilepsy 5
• Déjà vu/jamais vu experiences are associated with temporal lobe epilepsy 5
• More rapid time-course compared to migraine aura due to faster transsynaptic propagation of epileptic discharges 6
• Higher degree of differentiation of visual phenomena including color, movement, and complex visual phenomena 6

Critical Differential Diagnosis

The gradual onset and spreading pattern of aura is the key feature distinguishing it from transient ischemic attacks (TIA). 2

Migraine Aura vs. TIA

• Aura symptoms spread gradually over ≥5 minutes and occur in succession 1, 2
• TIA symptoms have sudden, simultaneous onset affecting a vascular territory 2
• If the patient has no visual aura symptoms, or presents simultaneous neurological symptoms corresponding to a cerebral vascular territory, emergency exploration for possible TIA is necessary 3

Migraine Aura vs. Epileptic Aura

• Migraine aura develops more slowly (≥5 minutes) due to cortical spreading depression 2, 4
• Epileptic aura has more rapid onset and progression due to faster neuronal discharge propagation 6
• Epileptic aura shows higher differentiation of visual phenomena and may include complex visual hallucinations 6

Red Flags Requiring Urgent Evaluation

Immediate neuroimaging (MRI brain with diffusion-weighted imaging) is recommended for: 7

• Visual aura symptoms persisting beyond 1 hour (normal maximum is 60 minutes) 7
• Persistent visual aura beyond 72 hours 7
• First-time aura with uncertain onset characteristics 3
• Late onset of aura or dramatic increase in aura attack frequency 3

Common Pitfalls to Avoid

• Do not dismiss persistent visual symptoms as "just migraine" without imaging, as this requires exclusion of structural or vascular pathology 7
• Do not assume acute onset visual aura is not migraine—acute onset aura can occur in migraine, though it is rare (4 out of 163 patients in one population study) 4
• Do not confuse the gradual spread of individual symptoms with the sequential occurrence of different symptom types—both are characteristic of aura 1, 2