en Gamma Knife Radiosurgery Case report <p style="text-align: justify;"><strong>Background & Importance</strong>: Idiopathic stenosis of the foramina of Magendie and Luschka is a rare cause of obstructive&nbsp;hydrocephalus involving the fourth ventricle.</p> <p style="text-align: justify;"><strong>Case Presentation:</strong> We reported the case of a 40-year-old woman who developed headaches and vertigo for several months&nbsp;and more recently gait disturbance. The CT scan showed quadri-ventricular hydrocephalus involving mainly the fourth&nbsp;ventricle with dilated lateral recesses. Craniocervical MRI confirmed hydrocephalus and also showed the brainstem and&nbsp;cerebellar tonsil herniation through the foramen magnum with hydromyelia and a hyperintense signal on T2 weighted&nbsp;MRI of cervical spinal cord. Biological analyses were normal. She underwent endoscopic third ventriculostomy (ETV).&nbsp;No complication was observed. The patient became asymptomatic during the weeks following the surgical procedure&nbsp;and remained stable at a mean follow-up interval of 20 months. Postoperative MR images demonstrated regression of the&nbsp;hydrocephalus; complete disappearance of brainstem and cerebellar tonsil herniation, hydromylia and the hyperintense signal on T2 weighted MRI of cervical spinal cord.</p> <p style="text-align: justify;"><strong>Conclusion:</strong> This case confirms the existence of hydrocephalus caused by idiopathic fourth ventricle outflows obstruction&nbsp;in adult and the efficacy of ETV for this rare indication.</p> Hydrocephalus, V4 foramina stenosis, ETV 26 29 http://irjns.org/browse.php?a_code=A-10-100-31&slc_lang=en&sid=1 Ibrahima Tine ابراهیما تاین 10031947532846003038 10031947532846003038 Yes Unit of Neurosurgery, Principal Hospital of Dakar, Dakar, Senegal, West Africa Abdou A. Diop عبدو ای. دیوپ 10031947532846003039 10031947532846003039 No Unit of Neurosurgery, Principal Hospital of Dakar, Dakar, Senegal, West Africa Ababacar Mbengue اباباکار امبنگو 10031947532846003040 10031947532846003040 No Department of Imaging, Principal Hospital of Dakar, Dakar, Senegal, West Africa Abdou K. Wimenga عبدو کی.ویمنگا 10031947532846003041 10031947532846003041 No Department of Neurosurgery, University Hospital Center of Fann, Dakar, Senegal, West Africa Paterne S. Mudekereza پاترن اس.مودکرزا 10031947532846003042 10031947532846003042 No Department of Neurosurgery, University Hospital Center of Fann, Dakar, Senegal, West Africa Seydou B. Badiane سیدو بی.بادیان 10031947532846003043 10031947532846003043 No Department of Neurosurgery, University Hospital Center of Fann, Dakar, Senegal, West Africa