Diagnostic Criteria

Consensus clinical diagnostic criteria for familial hemiplegic migraine (FHM) have been published by the (full text).

Suggestive Findings

FHM is a category of migraine with aura. Note: Migraine with aura is a recurring disorder of neurologic symptoms unequivocally localizable to the cerebral cortex or brain stem. The aura usually develops over a period of five to 20 minutes and lasts less than 60 minutes. Headache, nausea, and/or photophobia usually follow neurologic aura symptoms, either immediately or after a symptom-free interval of less than an hour. The headache usually lasts four to 72 hours but may be completely absent (acephalgic migraine).

Management Guidelines

Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with familial hemiplegic migraine (FHM) or simplex hemiplegic migraine (i.e., individuals with an FHM-causing pathogenic variant and an apparently negative family history), the evaluations summarized in this (if not performed as part of the evaluation that led to the diagnosis) are recommended. Table 4. Recommended Evaluations Following Initial Diagnosis in Individuals with Familial Hemiplegic Migraine System/Concern | Evaluation Neurologic | • Quantitative eye movement exam in persons w/nystagmus or complaints of incoordination or imbalance to look for additional clues of cerebellar involvement • EEG neuroimaging studies if seizures are present in order to further characterize seizure disorder • Neuroimaging studies in those w/impaired responsiveness to assess for cerebral edema Assess for movement disorder in those w/PRRT2-FHM Genetic counseling | By genetics professionals1 to obtain a pedigree inform affected persons their families re nature, MOI, implications of FHM in order to facilitate medical personal decision making Family support resources | Assess need for: • Community or such as Parent to Parent; • Social work involvement for parental support; • Home nursing referral. FHM = familial hemiplegic migraine; MOI = mode of inheritance 1. Medical geneticist, certified genetic counselor, certified advanced genetic nurse Treatment of Manifestations Symptomatic support during an episode of hemiplegic migraine is the only therapy available. Table 5. Treatment of Manifestations in Individuals with Familial Hemiplegic Migraine

Surveillance Guidelines

Table 6.

Recommended Surveillance for Individuals with Familial Hemiplegic Migraine

System/Concern | Evaluation | Frequency

Neurologic

| Eval by neurologist to assess change in attack frequency /or seizures, development of movement disorder, developmental delay, /or learning disability | Annually or more frequently for worsening symptoms