For roughly one in four migraine sufferers, an attack doesn’t begin with pain. It begins with a warning — a shimmering zigzag creeping across your field of vision, a patch of numbness spreading up an arm, or a strange difficulty finding the right words. This is migraine aura, and for those who experience it, it can be one of the more unsettling parts of living with migraine, precisely because it feels like something is happening to your brain in real time.
Understanding what aura actually is — and what may be setting the stage for it — can make it far less frightening, and can point toward more meaningful long-term solutions than simply waiting for the next one to pass.
What Migraine Aura Is
Aura refers to a set of temporary neurological symptoms that typically occur before or alongside a migraine headache. The most common form is visual aura: shimmering lights, zigzag lines, blind spots, or blurred vision that gradually spreads across part of the visual field, usually over 5 to 20 minutes. Aura can also involve:
- Sensory symptoms — tingling or numbness that migrates slowly, often starting in the fingers and spreading up the arm and into the face
- Language disturbances — difficulty finding words or speaking clearly
- Motor symptoms — temporary weakness on one side of the body (in rarer forms of migraine)
- Brainstem symptoms — dizziness, double vision, or unsteadiness (in migraine with brainstem aura)
Aura typically resolves within an hour and is usually followed by the headache phase, though in some people it overlaps with the headache or occurs without any headache at all.
Why Aura Happens: The Established Mechanism
The accepted explanation for migraine aura is a phenomenon called cortical spreading depression (CSD), first described by João Lelio Leão in 1944. CSD is a slow-moving wave of neuronal and glial depolarization that spreads across the surface of the brain at a rate of a few millimeters per minute — closely matching the speed at which visual aura symptoms are reported to spread across the visual field. As this wave passes through a region of the cortex, it triggers a brief burst of neuronal activity (correlating with the “positive” symptoms of aura, like flashing lights or tingling), followed by a longer period of neuronal silencing (correlating with the “negative” symptoms, like the blind spot or numbness that follows).
CSD is now understood to be accompanied by changes in blood flow in the affected region of cortex — typically an initial phase of increased blood flow, followed by a longer phase of reduced blood flow as the depolarization wave passes. This vascular response appears to be a secondary consequence of the underlying neuronal event rather than the root cause of aura itself, which represents a shift from older theories that treated migraine primarily as a vascular condition. CSD is also believed to activate the trigeminal nerve fibers surrounding the brain’s blood vessels, which is thought to be part of what triggers the headache phase that follows aura.
What Sets the Stage: The Upper Cervical Spine and the Brainstem
While cortical spreading depression describes what happens during aura, it doesn’t fully answer why one person’s brain becomes susceptible to this cascade in the first place, and why it happens again and again in the same individual. This is where the upper cervical spine — specifically the alignment of the atlas (C1) — becomes an important piece of the picture, because of its direct anatomical relationship to the brainstem and the structures that regulate intracranial pressure and blood flow.
The Myodural Bridge
The suboccipital muscles at the base of the skull attach directly to the dura mater, the membrane surrounding the brain and spinal cord, through a well-documented anatomical connection called the myodural bridge. When the atlas is misaligned, these muscles develop uneven tension, and that tension transmits directly through the myodural bridge onto the dura itself — including the dural sheath surrounding the brainstem. Since the dura is densely populated with pain-sensitive and pressure-sensitive nerve fibers, chronic dural tension from a misaligned atlas is a plausible ongoing source of irritation to the very brainstem structures involved in triggering and processing migraine.
Flanagan’s Choke Point Theory: CSF Backup and Increased Intracranial Pressure
Dr. Michael Flanagan has proposed that the craniocervical junction — the crowded anatomical space where the skull meets the top of the spine — can act as a mechanical choke point for the normal flow of cerebrospinal fluid (CSF). According to this theory, misalignment of the atlas can narrow this passage, restricting the normal circulation of CSF out of the skull and into the spinal canal. Over time, this theorized restriction is proposed to contribute to a mild backup of CSF and a subtle rise in intracranial pressure — a change that could plausibly irritate pressure-sensitive structures surrounding the brainstem, including the trigeminal and brainstem nuclei implicated in migraine.
Venous Drainage Restriction
The internal jugular veins, responsible for carrying blood out of the skull, also pass through this same narrow craniocervical space. The choke point theory extends to suggest that atlas misalignment may restrict this venous outflow as well, causing blood to back up within the skull. This venous congestion is theorized to compound the pressure changes described above, further irritating the brainstem and surrounding pain-sensitive structures.
It’s important to be transparent about the evidence behind these ideas: the myodural bridge is well-established anatomy. The broader choke point theory — encompassing CSF backup, increased intracranial pressure, and venous congestion as migraine contributors — is a hypothesis proposed by a single author and represents a theoretical framework used by many upper cervical practitioners to explain a subset of migraine and aura presentations, rather than an outcome confirmed through the same weight of research as more foundational neuroscience like cortical spreading depression itself.
Connecting the Mechanisms to Aura Specifically: A Neurogenic Vasoconstriction Theory
So how might upper cervical dysfunction connect specifically to aura, given that cortical spreading depression is the accepted underlying event? One theoretical explanation offered within upper cervical care is a neurogenic model: if the brainstem is under chronic irritation from myodural bridge tension, CSF backup, and venous congestion at the craniocervical junction, this irritation may abnormally influence the brainstem nuclei that help regulate vascular tone in the brain’s blood vessels.
Under this model, brainstem irritation from a misaligned atlas is theorized to provoke inappropriate vasoconstriction in cortical blood vessels — a narrowing of blood flow that could plausibly help provoke or lower the threshold for the cortical spreading depression wave that produces the aura itself. In other words, rather than aura being a purely spontaneous cortical event, chronic mechanical irritation of the brainstem from above may prime the vascular and neuronal environment in a way that makes an aura-triggering wave of cortical depolarization more likely to occur.
This neurogenic vasoconstriction concept should be understood as a proposed, complementary explanation offered by upper cervical practitioners for why aura recurs in some patients — not a replacement for cortical spreading depression as the established neurophysiological mechanism of aura, and not a claim that has been validated with the same rigor as CSD research itself.
What to Do When Aura Strikes
Regardless of the underlying mechanism, there are practical steps to take when aura begins:
- Get to a safe, calm environment. Aura can affect vision and coordination, so if you’re driving or operating machinery, stop as soon as safely possible.
- Avoid bright lights and screens. Sensory input can compound the discomfort of aura symptoms.
- Track the pattern. Note how your aura typically presents — which symptoms, how long they last, and how they progress. A first-time aura, or one that looks meaningfully different from your usual pattern, deserves medical evaluation to rule out other causes.
- Take migraine-specific treatment early, if your doctor has prescribed one, ideally as soon as aura begins rather than waiting for the headache to fully develop.
- Rest afterward. The postdrome phase following an aura and headache can leave you fatigued; give your body time to recover.
If your aura is new, unusually prolonged (lasting more than an hour), or accompanied by symptoms that feel different from your typical pattern, seek prompt medical evaluation to rule out other neurological causes.
Addressing the Root, Not Just the Aura
Medications and lifestyle strategies can help manage aura and the migraine that follows it, but they don’t address a potential underlying structural driver: chronic dysfunction at the craniocervical junction feeding ongoing irritation into the brainstem. For migraine sufferers whose aura recurs predictably and resists other interventions, an upper cervical evaluation can help determine whether atlas misalignment is contributing to the dural tension, CSF and venous restriction, and brainstem irritation theorized to set the stage for these attacks — and whether correcting that misalignment can reduce how often the body’s aura-triggering cascade gets set off in the first place.
What Upper Cervical Care Actually Involves
If you’re considering an evaluation, it helps to know what the process looks like. Upper cervical care begins with specific testing to determine whether a misalignment of the atlas or axis is present. If misalignment is confirmed, CBCT 3D imaging is used to precisely locate the exact pattern and direction of that misalignment, down to a fraction of a degree. This allows the correction to be tailored to the individual’s unique anatomy rather than applying a generic adjustment.
The correction itself is gentle and precise — there is no popping, twisting, or yanking of the neck involved. The goal isn’t just to shift the bones back into place temporarily, but to help the correction hold, so the surrounding muscles and ligaments stabilize the atlas in its corrected position over time. This is why many upper cervical patients find they need adjustments less and less frequently as their body learns to maintain the correction, rather than requiring ongoing, repeat manipulation session after session.
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a physician or qualified health provider with questions about a medical condition, and seek prompt medical evaluation for any new, prolonged, or unusual neurological symptoms.
Written by Dr. Drew Hall, Upper Cervical Chiropractor