Italian multicentre study on intrathecal fluorescein for craniosinusal fistulae

Cerebrospinal fluid leak (CSF), clinical sign of a dural lesion of the skull base, is a relatively rare event that can present with a variety of symptoms. Every craniosinus fistula should be considered a serious, potentially life-threatening situation (even those cases with hidden CSF leak). Reports of experience concerning diagnosis and treatment of craniosinus fistulae have appeared in the Literature. In the last few years, the endoscopic nasal approach is proving effective as it makes diagnosis much easier and is the least invasive surgical approach, with the greatest percentage of success. Various classifications are being proposed to improve clinical evaluation of CSF leaks and to simplify the diagnostic and therapeutic approach. The most common parameters of classification are: aetiology (traumatic, iatrogenic, non-traumatic, etc.) site, type of flow (high or low pressure) and, as far as concerns treatment, the type of graft used, all of which have contributed to various diagnostic and therapeutic algorithms being proposed. Therefore, the subject seems to be widely schematized and the therapeutic attitude widely agreed. However, one of the diagnostic and therapeutic approaches is now being questioned. For some, it is the heart of the clinical approach, while for others, it is a useful tool yet too dangerous to be used on account of potential side effects: namely, the fluorescein test. This procedure, consisting of intrathecal injection of a colorant (fluorescein), is well known by the Food and Drug Administration (FDA) which neither explicitly prohibits it, nor allows it, intrathecal administration is, therefore, an off label use. As far as the Authors know, authorization of this procedure has not been forthcoming anywhere in the world although the procedure itself is widely employed. As far as concerns the use of intrathecal fluorescein, many scientific papers have been written, clearly supporting its clinical usefulness. One limit to the use of fluorescein derives from frequent reports of complications, often related to the intrathecal administration; such complications are, however, always due to an incorrect dosage. In order to perform correct monitoring of any complication related to the use of intrathecal fluorescein and to investigate in a strictly scientific fashion, the legal problem related to the off label use (intrathecal administration) of an authorised substance, the Authors coordinated an Italian multicentre study aimed at establishig the tolerability of the lumbar intrathecal administration of fluorescein. Aim of the study was to review the literature focusing on CSF leaks, to set up to date diagnostic and therapeutic indications of fluorescein and to report the preliminary results of the Italian multicentre study.