You are an excellent assistant at finding disabilities in Spanish biomedical abstracts. You will be doing Named Entity Recognition for these disabilties and you must respond with each exact phrase as it appears in the article. If it appears multiple times, respond with each phrase separated by newline character. If there are no disabilities, respond with NA.

A disability is defined as:
a physical or mental condition that limits a person's movements, senses, or activities.


Abstract:

Background and objective Alternating hemiplegia of childhood ( AHC ) is a rare disease of unknown etiology characterized by early onset of recurrent episodes of hemiplegia , tonic or dystonic attacks and abnormal ocular movements with a fatal outcome to severe encephalopathy . Our aim was to describe the clinical manifestations , precipitating factors , complementary studies results , long - term outcome and response to treatment in a series of AHC patients . Patients and method Descriptive , retrospective and multicenter study in 17 Spanish patients aged between 1 - 24 years who fulfilled diagnostic criteria of AHC . Results 12 cases fulfilled criteria of typical AHC and 5 were atypical . Mean age at diagnosis was 26 months . 47% cases had a family history of migraine . Mean age at onset of hemiplegic attacks was 9 .6 months . Symptoms disappeared during sleep and precipitating factors were present in 94% cases . Most patients developed mental retardation with ataxia and dysarthria . Work - up tests ( metabolic , neurophysiologic and radiologic ) were normal or nonspecific . In 3 patients mutations in _CACNA1A , ATP1A2_ were ruled out . Positive responses to flunarizine was observed in 81% . Conclusions The characteristic clinical symptoms are still the clue to make the diagnosis of this mysterious disease , with a lack of genetic , biochemical or radiological specific studies . Early diagnosis avoids invasive tests , repeating procedures , using ineffective and potentially toxic treatments , and allows to start treatment with flunarizine without delay . More genetic studies are needed in broader series of patients .
Alternating hemiplegia of childhood
AHC
hemiplegia
AHC
AHC
typical AHC
mental retardation
ataxia
dysarthria