| IHS | Diagnosis | ICD-10 |
|---|---|---|
| 1.2.4 | Familial hemiplegic migraine (FHM) | G43.105 |
Description:
Migraine with aura including motor weakness and at least one first- or second-degree relative has migraine aura including motor weakness.
Diagnostic criteria:
- At least 2 attacks fulfilling criteria B and C
- Aura consisting of fully reversible motor weakness and at least one of the following:
- fully reversible visual symptoms including positive features (eg, flickering lights, spots or lines) and/or negative features (ie, loss of vision)
- fully reversible sensory symptoms including positive features (ie, pins and needles) and/or negative features (ie, numbness)
- fully reversible dysphasic speech disturbance
- At least two of the following:
- at least one aura symptom develops gradually over ≥5 minutes and/or different aura symptoms occur in succession over ≥5 minutes
- each aura symptom lasts ≥5 minutes and < 24 hours
- headache fulfilling criteria B-D for 1.1 Migraine without aurabegins during the aura or follows onset of aura within 60 minutes
- At least one first- or second-degree relative has had attacks fulfilling these criteria A-E
- Not attributed to another disorder1
Note:
- History and physical and neurological examinations do not suggest any of the disorders listed in groups 5-12, or history and/or physical and/or neurological examinations do suggest such disorder but it is ruled out by appropriate investigations, or such disorder is present but attacks do not occur for the first time in close temporal relation to the disorder.
Comments:
It may be difficult to distinguish weakness from sensory loss.
New genetic data have allowed a more precise definition of FHM than previously. Specific genetic subtypes of 1.2.4 Familial hemiplegic migraine have been identified: in FHM1 there are mutations in the CACNA1A gene on chromosome 19, and in FHM2 mutations occur in the ATP1A2 gene on chromosome 1. If genetic testing is done, the genetic subtype should be specified parenthetically.
It has been shown that FHM1 very often has basilar-type symptoms in addition to the typical aura symptoms and that headache is virtually always present. During FHM1 attacks, disturbances of consciousness (sometimes including coma), fever, CSF pleocytosis and confusion can occur. FHM1 attacks can be triggered by (mild) head trauma. In approximately 50% of FHM1 families, chronic progressive cerebellar ataxia occurs independently of the migraine attacks.
FHM is very often mistaken for epilepsy, and (unsuccessfully) treated as such.
