Tamoxifen treatment and occurrence of dural arteriovenous fistulas: An observational study on a series of patients presenting tamoxifen history and diagnosis of DAVf

Background Tamoxifen is an estrogen-receptor modulator frequently used in the treatment of non-metastatic breast cancer. Side effects of this treatment are well evaluated but unproven side effects are suspected by case reports. Only one case report evokes a possible association between tamoxifen and dural arteriovenous fistula (dAVF). Authors report in this study their experience on dAVF in women exposed to tamoxifen. Methods From 2005 to 2015, 294 patients with a dural arteriovenous fistula were referred to our department. Among these cases, 10 women who harbored 12 dAVFs were under a treatment of tamoxifen at the time of the diagnosis of the dAVF or had a treatment of tamoxifen in the past. There is no exclusion criterion for this observational study. Results Ten women were included in this series (mean age: 64). Seven women were under treatment when the first symptom occurred and the three others had already finished their treatment. The mean delay between the initiation of tamoxifen and the occurrence of symptom was 32 months. The most frequent clinical symptom was a tinnitus (8 patients, 80%) followed by headache (3 cases, 30%), chemosis (2 cases, 20%), oculomotor palsy (2 patients, 20%), and ocular hypertension (1 case, 10%). One patient presented a cerebellar hemorrhage and arrived in a comatose state. The fistulous point was located in the transverse sinus (TS) in 9 cases (75%) and in the cavernous sinus in 3 cases (25%). Conclusions Our observational study suggests that the occurrence of cranial dAVF could be influenced by tamoxifen. It will be very difficult to establish a causal link between them but a larger comparative study could help.