Tehran University Medical Journal

Before the recent outbreaks of Zika virus, few people have ever heard of its name. Even virologists had paid little attention to this member of the Flaviviridae family. Hence, up to January 2016, only 269 articles about Zika virus had been indexed in PubMed compared to the 9187 articles related to dengue virus. However, declaration of the World health organization (WHO) about the global Zika virus spreading, which has been associated with birth defects and some neurological problems, diverted more attention to this forgotten virus. Afterwards, the virus hit the headlines and became a research interest. Since then, up to 9 August 2017, the number of Zika related articles indexed in PubMed reached to 3214. Zika virus is a re-emerging arbovirus. The First detection of Zika virus was in Uganda in 1947. It belongs to the Flavivirus genus in the Flaviviridae family. Zika can typically cause a mild and self-limiting disease in a healthy person. However, in pregnant women, it might cause birth defects and occasionally it can be associated with peripheral neuropathy such as Guillain-Barre syndrome. Although many research have been conducted to find out the casual link between this virus and these disorders but this relationship is still dim and controversial. Considering its recent epidemics in 2015 and 2016 the geographical distribution of Zika virus seems to expand all over the world progressively. Interaction between virus and vector is dynamic. Variety of competent vectors and adaptability of virus to new arthropod vectors are the two major factors for this process. According to the last report published by WHO, 84 countries/territories in five continents have reported the circulation of Zika virus in their area. In the recent outbreak, WHO regional office in our region (EMRO) have reported no case of Zika virus transmission from this region. Nonetheless, because specific and competent vectors exist in some countries, this region has a potential of epidemic risk. Until now we have neither autochthonous nor imported case of Zika virus in our country but we should prepare for any unexpected situation. In this review, we will discuss new findings about the history, virological features, vectors, transmission routes and epidemiological aspects as well as laboratory diagnosis of Zika virus. In addition, the epidemiology of this virus in Iran will be discussed.

Background: Guillain-Barré syndrome is an autoimmune inflammatory disease, which manifests itself as an acute motor weakness of the organs, diagnosed as affecting the motor spinal nerve roots generally and causing muscle and motor weakness, the cause of this disease is the presence of active antibodies against the myelin sheath around the spinal nerve roots. Guillain-Barré syndrome is the most common and most severe unpleasant neuropathy that affects about 100,000 people worldwide annually.
Methods: This is a descriptive analytical study, the data of 354 admitted patients were reviewed and 262 cases, which matched the criteria for entering the study, was included. The criterion for entering the study was clinical diagnosis.Required information were included age, sex, complaints of disease, and visitation period. Data was analyzed by using Microsoft Excel 2013 (Microsoft Corp., Redmond, WA, USA) and study was performed on Imam Reza and Farabi Hospitals of Kermanshah in Iran, from March 1993 to February 2013.
Results: 59.5% were male and 40.5% female, and the mean age of the patients was 44.6±22.9. The most affected individuals were at the age of 30-50 and the highest prevalence was observed in spring. Acute inflammatory demyelinating poly-radiculoneuropathy with 53.4% was the most common backward disorder in patients and 5.7% among deaths among patients.
Conclusion: The results of the present study showed that Acute inflammatory demyelinating poly-radiculoneuropathy had the highest prevalence in patients and decreased with increasing age, and this syndrome was more prevalent in the spring.

The vagus nerve (VN), the longest cranial nerve and an essential part of the parasympathetic system, connects the central nervous system to respiratory, cardiovascular, immune, gastrointestinal, and endocrine systems and is involved in the maintenance of homeostasis by controlling these systems. Vagus nerve stimulation (VNS) is related to any method that would stimulate the vagal nerve via electrical stimulation. VNS is a Food and Drug Administration (FDA)-approved treatment for medication-resistant depression, drug-resistant epilepsy, and migraine. However, VNS has also been studied for various other conditions, such as Alzheimer's disease and tinnitus, by targeting the VN in the neck and ear. Currently, there are two methods for VNS: a) invasive-VNS (iVNS), which requires surgical implantation of a pulse generator under the anterior chest wall, that is linked through a wire to an electrode cuff that wraps around a cervical vagus nerve, b) non-invasive transcutaneous VNS which is separated into cervical transcutaneous vagal nerve stimulation (ctVNS) and auricular transcutaneous vagal nerve stimulation (atVNS). The non-invasive transcutaneous VNS techniques are well tolerated and have no significant side effects, making them effective in clinical research for brain diseases. Because with these newer methods, the electrical stimulation is carried out through the skin.
The results of this study were collected using the advanced search in Scientific Information Database (SID), Google Scholar, PubMed, and Scopus between 2011 to 2021. Out of 671 articles surveyed, we used 53 articles in the study after the evaluation. Medical Subject Headings (MeSH) and Keyword Searching was carried out through the MeSH database. VNS has been shown to alter neural activity in multiple areas of the brain related to the regulation of the affective states. However, the precise mechanism of VNS action on the clinical consequences is still unknown. This study aimed to review the therapeutic effect of both methods of VNS in neuropsychiatric and neurological disorders such as depression, migraine, seizure, tinnitus and Alzheimer's disease and discuss several hypotheses on the mechanism of VNS, as a new approach, in the treatment of such disorders. It considers that a brain-mapping approach is needed to discover the therapeutic mechanisms of VNS in brain diseases.