As of 1993 only approximately 30 people with<unk>  had been described in scientific literature. Due to the rarity and complexity of<unk> , it is not unusual for the initial diagnosis to be incorrect, or for diagnosis to be delayed for several months after the initial symptoms become apparent. The average age of diagnosis is just over 36 months. Diagnosis of<unk>  is not only difficult because of its rarity, but because there is no diagnostic test, making this a diagnosis of exclusion. There are several generally accepted criteria which define this disorder, however other conditions with a similar presentation, such as HSV encephalitis, must first be ruled out. Due to these diagnostic difficulties, it is possible that the commonness of the disease is underestimated. The following descriptions are commonly used in the diagnosis of<unk> . The initial four criteria for classifying<unk>  were that it begins before 18 months of age, includes attacks of both<unk>  on either side of the body, as well as other autonomic problems such as involuntary eye movement (episodic monocular nystagmus), improper eye alignment, choreoathetosis, and sustained muscle contractions (dystonia). Finally, patients suffer from intellectual disabilities, delayed development, and other neurological abnormalities. These diagnostic criteria were updated in 1993 to include the fact that all of these symptoms dissipate immediately upon sleeping. Diagnostic criteria were also expanded to include episodes of bilateral<unk>  which shifted from one side of the body to the other. Recent criteria have been proposed for screening for<unk>  early, in order to improve the diagnostic timeline. These screening criteria include focal or unilateral paroxysmal dystonia in the first 6 months of life, as well as the possibility of flaccid<unk>  either with or separate from these symptoms. Paroxysmal ocular movements should also be considered, and these should include both binocular and monocular symptoms which show in the first 3 months of life.
Alternating hemiplegia of childhood
Chronic paroxysmal hemicrania
Acute cerebellar ataxia of childhood
Ataxic cerebral palsy
Dyskinetic cerebral palsy
Babinski–Nageotte syndrome
Non-progressive congenital ataxia
Infantile progressive bulbar palsy