Migraine is a complex neurological disorder involving more than a simple, severe headache. Diagnosis is a clinical process, relying heavily on the patient’s description of symptoms rather than a single definitive test or biomarker. This approach is necessary because no specific blood test or imaging study can currently confirm or rule out migraine. A healthcare professional must carefully gather detailed information to match a patient’s experience with recognized medical definitions.
The Foundation: Detailed Medical History and Symptom Tracking
Diagnosis begins with a comprehensive medical history provided directly by the patient. This step focuses on understanding the pattern and character of the recurring head pain. The physician will inquire about the pain’s frequency and duration, which typically lasts between 4 and 72 hours if untreated. They will also ask about the pain’s location (often one-sided) and its quality (often throbbing or pulsating).
Patients should prepare by keeping a headache diary or tracking log. This log should detail the pain’s intensity and record associated symptoms like nausea, vomiting, or heightened sensitivity to light (photophobia) and sound (phonophobia). Tracking potential triggers, such as specific foods, stress, or sleep disturbances, is also helpful.
Clinical Diagnosis Using Established Criteria
Patient history data is analyzed against standardized guidelines to confirm a migraine diagnosis. Healthcare professionals use the International Classification of Headache Disorders, 3rd edition (ICHD-3), which provides specific criteria for various headache types. These criteria ensure consistency and help distinguish migraine from other disorders, such as tension-type or cluster headaches. For example, diagnosing migraine without aura requires the patient to have experienced at least five attacks meeting specific criteria.
The ICHD-3 mandates that the headache must exhibit at least two of the following characteristics: a unilateral location, a pulsating quality, moderate or severe intensity, and aggravation by routine physical activity. Furthermore, during the attack, the patient must experience at least one of the following: nausea and/or vomiting, or simultaneous photophobia and phonophobia.
Physical and Neurological Examination
Following the interview, the physician performs a physical and neurological examination in the office. This involves checking the patient’s reflexes, coordination, balance, and sensation. The doctor also assesses cognitive status and the function of the cranial nerves, which control movements in the face and eyes.
The purpose of this examination is to rule out other possible causes of the symptoms, not to diagnose migraine itself. A normal neurological exam between attacks supports a primary headache diagnosis, such as a migraine. Abnormal findings, however, act as “red flags” that may indicate a more serious underlying condition requiring further investigation.
Ruling Out Secondary Causes Through Diagnostic Tests
Diagnostic tests are generally not used to confirm a migraine, but rather to exclude other serious conditions. Tests like Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans are utilized to rule out secondary headaches. The physician orders these scans only when a structural problem in the brain is suspected, such as a tumor, aneurysm, or bleeding.
These exclusionary tests are ordered if the patient presents with atypical symptoms. Examples include a sudden, severe “thunderclap” headache, a change in the established headache pattern, or an abnormal finding during the neurological exam. An MRI is often preferred for its detailed imaging of soft tissues, while a CT scan is faster and used in emergencies to check for acute bleeding. If meningitis or another infection is suspected, a lumbar puncture (spinal tap) may be performed to analyze the cerebrospinal fluid.