The syndrom of Alternating Hemiplegia of Childhood (AHC) was first discribed in 1971 by Dr Verret and Dr Steele who reported eight cases of children with hemiplegia and migraine of which three indicated particular symptoms. The AHC syndrome was clearly identified and distinguished from other related diseases by a set of well defined criteria and was confirmed by several medical reports. A meeting on this syndrome was held in Rome 1992. Later in 1997 at a symposium in Seattle (USA) several hypotheses on possible causes of the syndrome were discussed and new ways of research methods were proposed (e.g. genetic studies). However the causes have remained unknown. To this day several examinations of children have not clarified the medical cause and mechanism of this syndrome. AHC is considered as a rare disorder. (Presently known cases in Germany: approx. 25-30)
2. General Criteria for Diagnosis
The criteria recognized as essential to carry the diagnosis are:
- Occurrence of the symptoms before the age of eight months. - Hemiplegic attacks affect alternatively both sides of the body - Occurrence of other paroxysmal (crampy/spasmodic) phenomena: - tonic attacks - abnormal ocular movements - paroxysmal (crampy) attacks of dyspnoea (shortness of breath) - autonomic phenomena coming along with / associated with hemiplegia or occurring independantly - Episodes of double hemiplegia or quadriplegia - Remarkably, the hemiplegia disappears, when the child falls asleep. It may reappear 10 to 30 minutes after awakening. - Progressive appearance of non-paroxysmal features: neurological signs (choreo-athetosis = jerky and bizarrely screwed movements), and developmental retardation.
3. Remarks
- The disease affects both boys and girls - Both the hemiplegic episodes and associated symptoms and signs vary with the individual patients. No clear correlation is apparent between the intensity and frequency of attacks and the degree of developmental delay. - The paralytic attacks and developmental delay persist at adolescence and continue into adulthood. Mental delay of various degree is present in most cases.
4. Disease manifestations
4.1. Hemiplegic or unilateral hypertonic attacks
Description:
One side (upper or lower limb) becomes flaccid (hemiplegic) or on the contrary stiff with flexion or hyperextension (hypertonic). Very characteristic eye movements (jerks) are frequent (nystagmus).
Frequency:
All the children have paralytic episodes ofvariable duration, from a few minutes to several days. The intensity of symptoms may fluctuate and they disappear temporarily during sleep. Precipitating/Accelerating factors may be noted. They include emotions (joy or fear), physical efforts or temperature changes. The effect of sleep on attacks is a very important feature of the condition.
4.2. Hemiplegic or bilateral episodes
Description:
Such episodes involve the four limbs, either in succession (shifting hemiplegia) or from the start (quadriplegia) often associated with marked dystonic phenomena. They are often associated with temporary loss of speech, abnormal eye movements, decreased awareness. Marked rigidity, crying (screaming) and apnea are often present.
Frequency and duration:
Such episodes are less frequent than hemiplegic attacks. They often last for hours or days and recur after disappearing during sleep, spontaneously or induced. Some degree of deterioration may follow the most severe episodes.
4.3. Epileptic manifestations
At present in some children only, they rarely occur during a hemiplegic episode. Most often they occur independently and require a specific antiepileptic treatment.
5. Consequences of the disease
The motor development can be variably impaired. Walking is often delayed, hypotonia is usual and imperfect control of movements and/or parasitic movements (choreoathetosis, dystonia) develop in most cases. The cognitive development is usually but not always impaired. School difficulties are inevitable. Today very few children follow a normal schooling with adapted support. The majority of the children needs education in specialized establishments (IMP, EMP, IMPRO type).
6. Behaviour
Affected children may be unstable, aggressive or depressed. They suffer changes of mood, usually of short duration, and are often anxious. Such disturbances do not seem to be related to medical therapy but dependent on the disorders itself. Mood changes may be premonitory of one attack.
7. Management
The medical follow-up and care aims at limiting the severity and intensity of attacks by a continuous treatment. So far sibelium (flunarizine) seems to be the most effective, even though in most children, it does not suppress the attacks and only moderately decreases the frequency of episodes. Other therapies are being currently studied. Careful follow-up and remedial help (physiotherapie, speech therapy, occupational therapy) are very important.
Report from a medical forum Alternating Hemiplegia of Childhood (AHC): a case presentation
S. Willers, D. Haffner, B.-Ch. Westphal, D. Hobusch Pediatric Hospital of University Rostock Alternating Hemiplegia of Childhood is a rare disease with unclear medical causes. It is characterized by spasmodic alternating hemiplegia, psychomotor retardation and neurological failure. The Typical signs of the paralysis mostly appear before the 18th month of life. Early symptoms during babyhood/infancy can be general hypotonia, intermittent abnormal eye movements, dystonia and autonomic dysfunction. The diagnosis is made clinically. We report about a 10 year old girl with typical symptoms of alternating hemiplegia. At the age of six months a left sided hemiplegia was noticed for the first time, which was interpreted as convulsive attacks. In the further process typical alternating hemiplegia appeared. They used to take between 30 minutes and several hours. The correct diagnosis was made then at the age of 28 months. Since that time our patient was treated probatively/probatorily with Flunarizine, Memantine, Primidone, Clobazam, Lamotrigene, Topiramate and Chloral hydrate - without any remarkable success, though. The paretic attacks' duration and severity however can be influenced/affeted advantageously by nacute therapy/treatment with Diazepam or Lorazepam. In January 2005 one could see epileptiform patterns (generalized ssw complexes and a positive photosensitivity). Now, our patient has been administered a therapy with Oxcarbazepine. As a possible cause of AHC we discuss metabolic disorder, a nneurotransmitter defect and migraine liken pathomechanisms. At certain patients we could veryfy/detect a mutation in the ATP1A2 gene.
