Migraines are a complex neurological condition, classified as a primary headache disorder, meaning the headache is not caused by another underlying health issue. Diagnosis relies almost entirely on a clinical assessment, as no single test (blood test, X-ray, or brain scan) can definitively confirm a migraine. A physician must carefully evaluate the patient’s symptoms and medical history against established diagnostic criteria to differentiate a migraine from other types of headaches. The accuracy of this diagnosis depends heavily on the detailed information a patient provides about their headache experience.
Preparing for the Appointment
A significant part of the migraine diagnosis occurs before the appointment, requiring detailed record-keeping. The most effective tool is a dedicated headache journal, which transforms vague recollections into concrete data points for the physician to analyze. This journal should document the frequency and duration of each attack, noting the exact date and time the headache started and ended.
Patients should rate the pain intensity using a standardized scale, typically from one to ten, and describe the quality of the pain, such as whether it is throbbing, pulsating, or dull. Crucially, the journal must record associated symptoms that help distinguish a migraine, including nausea, vomiting, or heightened sensitivity to light (photophobia) and sound (phonophobia). Identifying potential triggers is also necessary, requiring notes on factors like specific foods, stress levels, weather changes, or sleep patterns in the 24 hours preceding the attack.
The journal should also track the use and effectiveness of both over-the-counter and prescription medications taken during an attack, including the dosage and the time until any relief was felt. This documentation forms the foundation of the diagnostic process, allowing the doctor to see patterns that align with specific headache types and apply the clinical criteria for an accurate diagnosis.
The Clinical Assessment
During the appointment, the physician performs a comprehensive clinical assessment, which begins with a thorough review of the patient’s headache journal and medical history. The doctor uses the documented patterns of frequency, intensity, and associated symptoms to compare the patient’s experience against the International Classification of Headache Disorders, 3rd edition (ICHD-3) criteria. For a diagnosis of migraine without aura, for example, the criteria require at least five attacks lasting 4 to 72 hours, with at least two specific characteristics like unilateral location and pulsating quality, plus an accompanying symptom such as nausea or sensitivity to light and sound.
Following the history review, the physician conducts a physical examination, including a targeted neurological exam. This exam checks for abnormalities in the nervous system that might suggest a more serious underlying condition. The doctor assesses reflexes, coordination, muscle strength, balance, and sensory function, such as the patient’s reaction to light and touch.
A common component of the neurological assessment is fundoscopy, where the doctor examines the back of the eye to check the optic nerve for signs of swelling, which can indicate increased pressure within the skull. If the patient’s history aligns with the ICHD-3 criteria and the neurological examination is entirely normal, the diagnosis of a primary headache disorder like migraine is typically confirmed.
Ruling Out Other Causes
While the diagnosis of migraine is clinical, physicians may order tests like Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans, but these are primarily used for differential diagnosis. The purpose of imaging is not to confirm the presence of a migraine but to actively rule out secondary headaches caused by serious conditions. These conditions include brain tumors, aneurysms, bleeding, or infections, which present with symptoms that can sometimes overlap with migraine.
A doctor is prompted to order neuroimaging when the patient reports specific “red-flag” symptoms that signal a potential emergency. These red flags include the sudden onset of the “worst headache of life,” often described as a thunderclap headache, or a new headache pattern in a patient over 50 years old. Imaging is also indicated if the neurological exam reveals focal deficits, such as weakness on one side of the body or double vision.
Blood work may also be used to exclude systemic causes of head pain, such as infectious or inflammatory disorders. For a patient presenting with a classic, uncomplicated migraine history and a normal neurological exam, imaging is generally not necessary. These diagnostic tools are reserved for atypical presentations or when the physician suspects the headache is a symptom of a different medical problem.
When a Specialist is Necessary
A primary care physician can successfully diagnose and manage most cases of episodic migraine, but certain circumstances necessitate a referral to a neurologist or headache specialist. The first trigger for referral is diagnostic uncertainty, particularly when the headache presentation is complex or involves atypical neurological symptoms like persistent aura or motor weakness. Specialists possess deeper expertise in distinguishing rare headache disorders from typical migraine variants.
Another common reason for escalation is the failure of initial treatment attempts to provide adequate relief. If a patient does not respond to two or three different classes of standard preventive or acute medications, a specialist can offer more advanced and specialized treatment options. A referral is also warranted if the headache pattern becomes chronic, which is defined as experiencing headaches on 15 or more days per month for at least three months.
Specialists can offer more targeted treatment plans, including procedures like nerve blocks or Botox injections for chronic migraine. Their comprehensive evaluation ensures the patient receives the most appropriate and tailored care for a condition that has become difficult to manage in the general practice setting.