1.1 Introduction
Sigmoid sinus thrombosis (SST) is a rare but dangerous intracranial complication that usually comes from middle ear infections. It may cause infectious or neurological complications, such as meningitis or hydrocephalus, respectively. [1, 2, 3]
Although these are quite rare complications, the literature provides no definitive consensus in their management, especially in terms of surgery and the use of anticoagulants. Surgical management includes myringotomy with or without mastoidectomy. There is no consensus regarding the use of anticoagulation treatments in otogenic SST. Some ENT surgeons favor its use as it reduces the risk of embolization and enhances the neurological prognosis, while others think that the risks of hemorrhagic complications outweigh this, and that using anticoagulants does not improve the clinical or the radiological outcome. [1, 2, 3, 4, 5, 6, 7, 8]
Therefore, this study aims to provide a systematic review on the use of additional anticoagulation in the management of the otogenic SST. Based on the data from the review of literature, a descriptive comparative analysis was carried out to see if the outcomes were better in the anticoagulation group when compared with the cohort not receiving anticoagulant medication.
1.2 Material and methods
This study is a systematic review of the literature on otogenic SST. Keywords 'Otogenic, sigmoid, sinus, thrombosis and anticoagulant' were used in PubMed and Embase, in order to search for all relevant literature up to 2020. The articles found were firstly screened with the help of titles and abstracts, after this they were either selected for full reading or disregarded, as were the references from these articles. Selective criteria were then applied to the review, in order to constitute a database with the articles. The data were then rearranged into different tables so we could continue with our descriptive study.
1.3 Results
The initial search results identified 251 articles. After an overview based from the abstracts of the different studies, 40 publications were identified as useful and fully analysed and all their references were reviewed. After applying the inclusion and exclusion criteria, only 16 articles were finally selected to constitute the data for the analysis, consisting of 113 patients. Complications appeared in 26 patients, whereas 78 patients achieved recanalization.
The group who received anticoagulation medication had more complications (23,33%) compared with the group who were not anticoagulated (21,74%), whereas the recanalization was far more successful in the anticoagulated group, 76,67%, compared with 39,13% in the patients not anticoagulated. However, a selection bias may be considered as 90 patients were present in the anticoagulated group, whereas only 23 were considered in the comparative group. The patients were then divided into three groups based on the types of treatments they received. The first subgroup with 74 patients received anticoagulation along with mastoidectomy. The recanalization was achieved in 72,97% of them, whereas nineteen patients showed complications (25,68%). The second group with 16 patients also received anticoagulation but conservative surgery (myringotomy and antibiotics or antibiotics alone). The recanalization and the complication rates were 93,75% and 12,50% respectively. In the 90 patients anticoagulated, only 2 had haemorrhagic complications (2,22% of the patients), and only 1,11% if we exclude nose bleeds. The third group with 23 patients were treated with mastoidectomy and antibiotics but not anticoagulated. The recanalization were reported in only 39,13% with a reported complication rate of 21,74%. There was no mortality in the whole series of patients.
In addition, the subjects were evaluated following the recanalization of the sinus by radiology, with at least partial blood flow compared against no blood flow. The difference with the results presented in the previous paragraph is that the purpose was only to see the impact of the treatment on the recanalization and on the clinical complications, whereas here, the aim is to highlight the impact of the recanalization on the clinical outcome. Thus, the results are not only based on the treatments used, but also on the recanalization state of the patients’ sigmoid sinuses for each treatment modality. Due to the lack of details reported in some studies, the number of patients differs from the previous paragraphs. For example, if the complications were given for the patients with a type of treatment but without giving the radiological outcome for each complication, the data was used in Table 1.2 and 1.3 but could not be used in Table 1.4 or 1.5. For those patients who underwent mastoidectomy with concurrent anticoagulation, 44 showed recanalization, and 12 of them showed neurological complications (27,27%). In sixteen patients that received the same treatment, no recanalization was achieved, and 3 (18,75%) had neurological complications. In the second group (who received anticoagulation and myringotomy), 12 patients showed recanalization, and only one had a neurological complication (8,33%). The only patient not recanalized developed a neurological complication (100 %). Finally, for the patients without anticoagulation, five patients achieved recanalization and developed no complications, and only one presented with a neurological complication out of 7 of the patients that did not become recanalized (14,29%).
Afterwards, based on the findings from the radiological images, the patients were independently reorganized into 2 clusters of treatment modality, to see the association between the recanalization and the clinical outcome. Sixty patients showed recanalization, and 13 of them presented with complications (21,67%). On the other hand, 24 did not show recanalization, and 5 of them had complications (20,83%). The overall number of patients is not equal to 113 for the same reasons mentioned in the previous paragraph; a lack of availability of data.
1.4 Conclusion
From this review, it seems as though the anticoagulation medication was helpful for the radiological recanalization. However, it did not seem to influence the clinical outcome.
Only 1 major haemorrhagic complication occurred in the review, for a total of 90 patients that benefited from the anticoagulant, thus, it may be relatively safe to use.
Regarding the recanalization, it is not possible to confirm an improvement in the clinical outcome, as more complications appeared in the overall number of patients recanalized.
As this study is purely descriptive, only hypothetical conclusions can be made. Therefore, to improve the quality of this study, and in order to prove our hypothesis, a statistical meta- analysis of the data presented should be completed, along with a prospective study.
In addition, it is highly important to recognize that the major limitation of this review is the lack of standardization in the published studies, which results in a lack of relevant data, and therefore a lack of patients that can be used, which automatically generates a selection bias and affects the quality of the results.