Migraine is an inherited neurological disorder which causes a collection of symptoms including headache, brain fog, nausea or vomiting, and sensitivities to light, sound, smells and touch. A more unusual type of migraine, Hemiplegic Migraine, may also cause weakness or paralysis on one side of the face, the arm or leg or all down one side. The weakness is twice as likely to be in the upper arm as in the leg according to one study. This can occur as a part of the aura phase and be quite transient or it can persist as the headache comes on. The weakness can last anything between half an hour to several days. Occasionally the headache comes on first.
There are two main types of hemiplegic migraine.
Familial Hemiplegic Migraine (FHM)
This variant occurs where there is clear evidence of one or more family members suffering one-sided weakness during their migraine attacks. There are currently four genes known to be associated with this type. Four sub-types are described in the IHCD classification of headache. Roughly 50% of children with a parent with hemiplegic migraine will develop this type of migraine.
Sporadic Hemiplegic Migraine (SHM)
This is a variant where only one person in a family is known to get the one-sided weakness with migraine. It is thought to be due to spontaneous mutations of genes but may also affect someone with a family member who has the genes but has not been affected.
Genetic testing is not necessary for either type of Hemiplegic Migraine.
Symptoms of Hemiplegic Migraine
- – Motor weakness or paralysis on one side of the body (Hemiplegia)
- – Headache
- – Trouble speaking
- – Phonophobia (increased sensitivity to sound) and/or photophobia (increased sensitivity to light)
- – Other typical aura symptoms – vision changes (sparkles, shimmers, visual field defects), numbness, tingling
- – Impaired state of consciousness – mild confusion to profound coma
- – Nausea and/or vomiting
- – Ataxia (defective muscle coordination which can cause staggering or walking difficulties)
Diagnosis is based on the presence of having at least 2 attacks with:
- – aura accompanied by fully reversible motor weakness and fully reversible visual, sensory, and/or speech/language symptoms; and
- – at least 2 of the following 4 characteristics:
- – at least one aura symptom that spreads gradually over ≥5 minutes, and/or two or more symptoms that occur in succession
- – each individual non-motor aura symptom lasting 5 to 60 minutes, and motor symptoms lasting <72 hours
- – at least one unilateral (one-sided) aura symptom
- – the aura being accompanied by headache, or followed by headache within one hour 
Attacks often start in childhood and may be alarming. A thorough history and examination with relevant investigations (including appropriate brain scanning) is essential to exclude other causes of weakness. The symptoms may be thought to be caused by a tumour, epilepsy or a stroke when they initially occur and these need to be excluded if there is any doubt.
The hemiplegic symptoms may just last for an hour but in some cases can persists for several hours, days or, in some rare variants, even weeks. In two-thirds of people, the symptoms last less than a day. Usually they will resolve completely in between attacks. The impact can be high especially if attacks are frequent.
Hemiplegic migraine can respond to many of the lifestyle, acute treatments and preventative treatments used for any type of migraine, but it is important to get advice from a headache specialist for this more unusual type of migraine.
This information is provided as a general guide only and is not a comprehensive overview of prescribing information. If you have any queries or concerns about your headaches or medications please discuss them with your GP or the doctor you see at the National Migraine Centre.