Headache attributable to nonvascular intracranial disorders.

Headache attributable to nonvascular intracranial disorder is a basket of multiple, partly complex, and very diverse idiopathic or secondary disorders. By definition, the headache has to occur in a close temporal relationship to the intracranial disorder. Some of these headache disorders are caused by high or low cerebrospinal fluid pressure; noninfectious inflammatory diseases such as neurosarcoidosis, aseptic (noninfectious) meningitis, and lymphocytic hypophysitis; or intracranial neoplasm. Other nonvascular headaches, including hemicrania epileptica and postseizure headache, Chiari malformation type I, and the syndrome of transient headache and neurological deficits with cerebrospinal fluid lymphocytosis, are attributed to hypothalamic or pituitary hyper- or hyposecretion, intrathecal injection, or epileptic seizures. The clinical presentation of all these disorders can be diverse and often mimics the characteristics of primary headaches, which may delay the diagnosis.