<unk>  in<unk>  may be classified according to presence or absence of underlying disorder into two subtypes: primary<unk> disorders and secondary<unk> disorders.
Based on the duration of symptoms,<unk>  in<unk>  may be classified as either acute or chronic.
Headaches in children classification
Headache classification
Alcohol withdrawal classification
Amnesia classification
Delirium classification
Biliary dyskinesia diagnostic criteria
Attention-deficit hyperactivity disorder classification
Asperger syndrome classification