Familial Hemiplegic Migraine - Diagnosis

Diagnosis

Diagnosis of FHM is made according to the following criteria:

• Two attacks of each of the following:

• Aura with motor weakness accompanied by either reversible visual symptoms (flickering lights, spots, lines, etc.), reversible sensory symptoms (pins and needles, numbness, etc.) or speech symptoms.
• At least two occurrences of:

• One or more aura symptoms that develop over at least 5 minutes
• These symptoms lasting more than 5 minutes and less than 24 hours
• Headache beginning within 60 minutes of aura onset. These headaches can last 4–72 hours, occur on only one side of the head, pulsate, be of moderate to severe intensity, and may be aggravated by common physical activities such as walking. These headaches must also be accompanied by nausea/vomiting, phonophobia (avoidance of sound due to hypersensitivity) and/or photophobia (avoidance of light due to hypersensitivity).

• At least one close (first or second degree) relative with FHM
• No other likely cause

Sporadic forms follow the same diagnostic criteria, with the exception of family history.

In all cases, family and patient history is used for diagnosis. EEG and brain imaging techniques, such as MRI and CAT scans, are used to rule out epilepsy and to test for cerebellar degeneration, respectively. With the discovery of causative genes, genetic sequencing can also be used to verify diagnosis (though not all genetic loci are known).