**7. Treatment of tuberculous meningitis**

Various guidelines recommend an intensive first phase, with the use of four drugs: rifampicin, isoniazid, pyrazinamide (RHZ) + streptomycin (S) or ethambutol (E) or ethionamide [39–41]. There follows a continuation phase consisting in the administration of two drugs (RH), the total duration of treatment varying in different protocols between 9–12 months. For newly diagnosed TBM cases, intensive phase treatment will consist of 8 weeks of isoniazid, rifampicin, pyrazinamide and ethambutol. According to the recommendations of the Center for Disease Control and Prevention (CDC) and Infectious Diseases Society of America, the ideal duration of antituberculosis treatment should be between 9–12 months [39]. The British Infection Society recommends 12 months of treatment, and the WHO considers that 9–12 months of antituberculosis medication would be sufficient to reduce complications and sequelae [40, 41]. Clinical and biological monitoring should be performed at least once a month to observe any adverse reaction to the antituberculosis treatment. However, the optimal treatment of TBM has not yet been established in clinical trials. The same drug can have different pharmacokinetics in the blood and in the CSF.

#### **7.1 Isoniazid**

