As the conclusions of the ARUBA Study are strongly oriented towards therapeutic abstention, we think it is appropriate to express the concern of the Italian Society of Neurosurgery for the impact that this study might have on the health of patients, if not properly evaluated. The vast majority of patients (76-81%) included in the study was treated with endovascular or radiotherapy treatments, alone or in combination. Only 18 patients (19%) had surgery. It is well known that a partial treatment of arteriovenous malformations (AVMs), as is often the case with endovascular therapy, may increase the risk of bleeding. The primary endpoint (death or symptomatic stroke) in the treated group was reached in 30.7%, i.e. almost one-third of the subjects. This has no comparison in the current surgical literature. Considering permanent and transient neurological deficits along with headaches and seizures all together in the same outcome evaluation parameter may be inappropriate and misleading. The graph with all results from the ARUBA Study, which claims to be the demonstration that natural history is better that treatment, clearly shows that what is assumed to be treated has not actually been treated. If death or stroke occur a few years from treatment, it only means that the disease was not cured and patients received a partial - therefore ineffective, if not dangerous - treatment. An effective treatment, as surgery is, must have a flat follow-up curve. The ARUBA Study shows that incomplete treatment leads to negative outcome, confirming that an integrated multidisciplinary strategy has to be plotted out before starting any treatment and that a complete exclusion of the AVM must be achieved.