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 Aura (Rare)

Motor symptoms are uncommon, occurring in only 6% of patients 4. Important characteristics:

• Typically half-sided, affecting the hand and arm 4
• May last up to 72 hours, unlike other aura types 1
• Duration beyond 60 minutes is acceptable for motor symptoms 1

Other Aura Types

Less common manifestations include 1, 2:

• Brainstem aura with symptoms originating from brainstem structures
• Retinal aura affecting one eye specifically
• Epileptic auras including epigastric sensations (rising feeling from abdomen), déjà vu/jamais vu experiences, and autonomic symptoms 5

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
• When multiple aura symptoms occur, they usually follow the sequence: visual → sensory → aphasic 3, 4

Epileptic Aura

In epilepsy, aura refers to abnormal sensations in the pre-ictal phase before seizure onset 5, 6. Key distinguishing features:

• Higher degree of differentiation of visual phenomena including color, movement, and complex visual phenomena 7
• More rapid time-course due to faster transsynaptic propagation of epileptic discharges compared to migraine's cortical spreading depression 7
• May include epigastric aura (common in temporal lobe epilepsy), experiential aura, or sensory aura 5
• Provides important lateralizing and localizing information for presurgical assessment 5

Critical Differential Diagnosis

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

Migraine Aura vs. TIA

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

Migraine Aura vs. Epileptic Aura

• Epileptic aura: More rapid progression, higher differentiation of visual phenomena, may include complex visual hallucinations 7
• Migraine aura: Slower spread (≥5 minutes), typically simpler visual phenomena like scintillations and fortification spectra 7
• Additional positive motor phenomena or transition to complex partial seizure supports epilepsy diagnosis 7

Red Flags Requiring Urgent Investigation

Immediate neuroimaging (MRI brain with diffusion-weighted imaging) is recommended for: 8

• Visual aura persisting beyond 1 hour (abnormal, as normal duration is 5-60 minutes) 8
• Visual aura lasting beyond 72 hours 8
• First-time aura with uncertain onset characteristics 3
• Late onset of aura 3
• 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 8
• Do not give triptans during ongoing aura, as they are ineffective for aura symptoms and contraindicated in basilar or hemiplegic migraine 8
• Recognize that acute onset aura (without gradual spread) is a real but rare phenomenon that still warrants careful evaluation 4
• Be aware that some epileptic auras may not show clear EEG correlates, particularly viscerosensory and experiential types 5