Surgical treatment of patients with idiopathic obstruction of the foramen of Monro

Abstract

Introduction. Idiopathic obstruction of the foramen of Monroe is an extremely rare pathology in adults and accounts for 1 % of all forms of occlusive hydrocephalus. The largest described series of patients with such pathology includes 4 adult patients. Four types of the foramen of Monro obstruction have been distinguished: type A – atresia, or stenosis, type B – morphological obstruction (membrane), type C – functional obstruction, type D – patent foramen. These patients usually undergo endoscopic or shunting surgery. Currently no algorithm exists for the treatment of such patients.Materials and methods. From 2004 to 2019 year 251 adult patients with idiopathic hydrocephalus were treated at the N. N. Burdenko National Medical Research Center of Neurosurgery. Of these, 11 people (4.4 %) had signs of obstruction at the level of the foramen of Monro. The average age of the patients was 41.9 years (25–67 years). The condition was more prevalent among women (8 female, 3 male patients). The most common symptoms were headaches and nausea. None of the patients showed signs of intracranial hypertension upon examination of the fundus. Magnetic resonance imaging of the brain demonstrated expansion of one or both of the lateral ventricles, stenosis of foramina of Monro, or their occlusion by membranes.Results. Patients were divided into 3 groups depending on the type of foramen of Monro obstruction. Type A obstruction was observed in 8 patients: in patients with unilateral obstruction (3 patients), only septostomy was performed, while among the patients with bilateral obstruction, 3 patients underwent septostomy followed by reconstruction and stenting of the right foramen of Monro (1 of these patients later required a shunting procedure), and in 2 patients, a shunting procedure was performed at initial presentation. Type B obstruction was observed in 2 patients: a patient with unilateral obstruction underwent septostomy and dissection of the membrane, and 1 patient with bilateral obstruction underwent septostomy, dissection of the membrane, and foraminal stenting. In a patient with type C obstruction, a septostomy and stenting of the right foramen of Monro were performed. Based on postoperative MRI data, the dimensions of the ventricles of the brain decreased or did not change. Most patients showed a complete regression of symptoms or their significant reduction, while one patient’s condition stabilized after surgery. There were no fatal outcomes or persistent complications. The follow-up period ranged from 4 to 60 months (29.4 months on average).Conclusion. In cases of idiopathic obstruction of the foramen of Monro, endoscopic surgery can be used as the treatment of choice.