Other less common symptoms include nausea, vomiting, pancreatitis, diabetes or recurrent venous thrombosis. Tonsillectomy is mainly undertaken for sleep apnea and recurrent or chronic tonsillitis. Epilepsy is a group of neurological disorders characterized by recurrent epileptic seizures. There is no evidence of chronic or recurrent infection with "Variola virus". A discontinuation syndrome can occur after stopping any antidepressant which resembles recurrent depression. Brittle asthma is a kind of asthma distinguishable by recurrent, severe attacks. In cases of recurrent or persistent fever, an antifungal agent should be added. Epilepsy is characterized by a long-term risk of recurrent seizures. Bilateral injury to the recurrent laryngeal nerve would cause this condition. Ixabepilone is being researched as a possible chemotherapy for advanced or recurrent endometrial cancer. The diagnosis hinges on the presence of single or recurrent major depressive episodes. The frequency and severity of recurrent outbreaks vary greatly between people. Combretastatin and pazopanib are being researched in combination for recurrent ovarian cancer. The antibiotic rifaximin may be recommended in addition to lactulose for those with recurrent disease. The occurrence of recurrent pregnancy loss is 1%.