Alternating hemiplegia of Childhood is a condition that causes transient weakness of either, or both, sides of the body. The attacks may alternate or sometimes overlap, that is the second side is affected before the first recovers. Attacks start in the first eighteen months of life but the earliest episodes are often unusual irregular eye movements. The attacks last from less than an hour, which is unusual, to several days. When the attacks are prolonged the manifestations are not apparent during sleep or for the first fifteen to twenty minutes on waking when they then return. This is a very characteristic finding and when there are bilateral attacks, this may allow feeding and drinking to occur in that short clear period after waking. The episodes of hemiplegia are not epileptic in nature but epileptic seizures also occur in about half of those affected and require separate anti-epileptic drug treatment.
What causes it?
Scientists discovered in 2012 that, in 75% of those affected, AHC is caused by specific mutations in the gene ATP1A3. (See “Cause of AHC identified” section). Affected children usually have significant learning disabilities and motor organisational problems, including unsteadiness. Although there is a concern that these problems may increase with repeated episodes, the available evidence does not support this.
All children and young adults are different and have different triggers. Some common ones are as follows:-
Water – bathing and swimming.
Changes/extremes of temperature.
Bright lights and loud noises.
Fluorescent lights/Low energy bulbs
Strong odours(Perfumes etc)
Childhood illnesses and infections.
Tiredness and lack of sleep.
What’s the treatement
The treatment most commonly used is flunarizine (a calcium channel blocker). Other drugs have not been found to be consistently helpful. Management is complex because of the multiple impairments and episodic deterioration. Bilateral attacks (those that occur on both sides of the body) may pose hazards for nutrition, hydration and breathing.
As each child is so different with this condition a treatment or medication that works for one will not necessarily work for another.
From a parents point of view other drugs that have been beneficial on individuals include topamax, epanutin, pitzotifin.
Various other anti-convulsant drugs are used and anti-migraine drugs have been tried.