Basilar migraine, now formally termed migraine with brainstem aura (MBA), is a less common subtype of migraine characterized by aura symptoms originating from the brainstem. Because these symptoms closely mimic life-threatening neurological events, diagnosis is challenging and requires a meticulous, multi-step process. A physician must gather clinical evidence and systematically rule out other serious medical conditions to confirm the symptoms are temporary and not caused by structural damage. This process ensures the patient receives the correct diagnosis and management plan.
Recognizing the Distinctive Symptoms
A basilar migraine attack is distinguished by an aura involving two or more fully reversible symptoms pointing to brainstem dysfunction. Patients frequently experience intense vertigo—the overwhelming sensation that the room is spinning—which must be differentiated from simple dizziness. Another common occurrence is dysarthria (slurred speech), which is fully transient.
The aura can also include sensory disturbances like tinnitus (persistent ringing in the ears) or decreased hearing (hypacusis). Visual symptoms often manifest as double vision (diplopia) or simultaneous visual changes in both the temporal and nasal fields of both eyes. Loss of coordination, or ataxia, can impair balance, causing the patient to appear unsteady. Importantly, the symptoms must be fully reversible and must not include any motor weakness, which would suggest a different diagnosis like hemiplegic migraine.
The Role of Neurological Assessment and History
The diagnostic journey begins with a thorough patient history, which is the most informative component. The doctor asks specific questions about the frequency, duration, and complete reversibility of the neurological symptoms, as their transient nature is the hallmark of a migraine aura. Understanding the patient’s family history is also important, as migraine disorders often have a genetic component.
A physical neurological examination is performed, ideally during or immediately following an attack, to assess balance, coordination, speech, and cranial nerve function. The physician evaluates whether the symptoms are a true reflection of brainstem dysfunction, such as true vertigo rather than general lightheadedness. This clinical data gathering is crucial for collecting the evidence needed to satisfy the formal diagnostic criteria.
Establishing the Formal Criteria
A definitive diagnosis of migraine with brainstem aura relies on meeting the operational criteria established by the International Headache Society (ICHD-3). The patient must have experienced at least two attacks that fulfill the set requirements. A key criterion is that the aura must involve at least two of the specific brainstem-related symptoms, such as vertigo or ataxia, which must be completely reversible.
Furthermore, the aura symptoms must last between five and sixty minutes, and the headache phase of the migraine must begin during the aura or within 60 minutes after the aura has ended. The diagnosis is further specified by the absence of motor weakness, which distinguishes it from hemiplegic migraine. Adhering to these strict, internationally recognized guidelines provides a consistent framework for classifying this complex headache disorder.
Differential Diagnosis and Exclusionary Testing
Because the symptoms of migraine with brainstem aura often mimic conditions like stroke or transient ischemic attack (TIA), the diagnosis is one of exclusion. Serious vascular or structural causes must be ruled out before the migraine diagnosis can be confirmed. This ensures patient safety and prevents the misdiagnosis of an acute neurological emergency.
To exclude these serious conditions, a physician typically orders advanced neuroimaging studies. Magnetic Resonance Imaging (MRI) checks for structural abnormalities, tumors, or evidence of a stroke. Computed Tomography (CT) scans may also be utilized in an emergency setting to quickly rule out acute hemorrhage. Magnetic Resonance Angiography (MRA) visualizes the blood vessels, helping to exclude vascular issues like blockages. The final confirmation of migraine with brainstem aura relies on a normal neurological workup in a patient whose clinical presentation precisely matches the ICHD-3 criteria.