In a study of fifteen female and nine male patients with alternating hemiplegia, a mutation in ATP1A3 gene was present. Three patients showed heterozygous de-novo missense mutation. Six patients were found with de-novo missense mutation and one patient was identified with de-novo splice site mutation. De novo mutation is a mutation that occurs in the germ cell of one parent. Neither parent has the mutation, but it is passed to the child through the sperm or egg. Diagnosis
There is no diagnostic test for alternating hemiplegia, which makes it very difficult to diagnose. Also, because alternating hemiplegia is extremely rare, it is frequently missed and the patient is often misdiagnosed. Proper diagnosis, however, is critical for early treatment of the disorder. There are many criteria that can help in the proper general diagnosis of alternating hemiplegia. Criteria for diagnosis
First, the symptoms must be observed before the patient is 18 months of age. Second, there must be frequent episodes of hemiplegia, involving either side of the body. Third, other paroxysmal disorders including tonic attacks, dystonia, nystagmus, strabismus, dyspnoea, and other uncontrollable disorders are noticed to occur. Although common, the paroxysmal disorders involving the eye, nystagmus and strabismus, may not be apparent in older children and may not have been remembered in childhood so a lack of these symptoms does not rule out alternating hemiplegia. Fourth, all symptoms clear up directly after falling asleep and usually come back after waking during an attack.
People with alternating hemiplegia are often underweight and with the help of dietitians, a meal plan should be developed for times of attack when consumption of food may be difficult. : 779–780

See also
Hemiplegia
Alternating hemiplegia of childhood
Webers syndrome
Medial medullary syndrome
Familial hemiplegic migraine
Brain stem stroke syndrome

References
External links

alternatinghemiplegia at NINDS