[Chronic meningitis: aetiologies, diagnosis and treatment].

PURPOSE: Chronic meningitis are very uncommon and account for less than 10% of all meningitis cases. Their symptoms are uncunth and there outcome is insidious. Therefore, they remain often unknown. There are only a few published reports on this disease, so diagnosis and therapeutic approachs are difficult. CURRENT KNOWLEDGE AND KEY POINTS: Positive chronic meningitis diagnosis is easy. However, determining the cause of chronic meningitis remains dilemma, as many infectious and noninfectious processes (including inflammatory, neoplastic or autoimmune aetiologies or as a result of a chemical exposure) can result in the chronic meningitis syndrome. In order to institute a pertinent treatment, sometimes urgently needed, diagnostic approach must be extremely rigourous and accutely orientated. Nevertheless, although extensive investigations, 30% of the aetiologies remain undetermined. Only two choices are left for the medical physician: an aggressive attitude based on complementary investigations or a contemplated therapy with a close clinical and biological control. On the other hand, when the patient's condition is quickly deterioring without a clear and proved aetiology, it is sometimes necessary to institute an empirical treatment, not always properly determined and sometimes contreversial. Besides, few reports on prognosis and outcome od idiopathic chronic meningitis have been published. FUTURE PROSPECTS AND PROJECTS: After a review of aetiologies and diagnostic investigations chronic meningitis, we propose a practical experience attitude about management and treatment of chronic meningitis. Thus, large-scale studies about the follow up chronic meningitis in long term, in particular those without aetiology, treated or no, should improve the outcome of this chronic syndrome.