Mystery Case: Idiopathic bilateral stenosis of the foramina

A 42-year-old man presented with chronic, continu-ous, bifrontal pressure headaches, slightly worse in the morning, forgetfulness, and confusion. There was no history of prior CNS hemorrhage or infec-tion. The neurologic examination was unremarkable. No papilledema was present. Neuroimaging demon-strated symmetric enlargement of the lateral ventricles, a slit-like third ventricle, and downwards transtentorial herniation (figure 1). No mass lesion or abnormal enhancement was seen. A diagnosis of idiopathic bilateral stenosis of the foramina of Monro was considered. The patient underwent endoscopic Figure 1 MRI of the brain Axial T2-weighted images demonstrate dilated lateral ventricles. The third ventricle is slit-like. There is downwards tran-stentorial herniation of the midbrain. Figure 2 Intraoperative endoscopic photographs (A) Intraoperative endoscopic photograph shows a thin, translucent membrane covering the left foramen of Monro (aster-isk). There is no evidence of tumor. (B) A Fogarty catheter was inserted through this web and inflated. (C) After removal of the catheter, a patent foramen of Monro is seen. A septostomy was subsequently performed to allow CSF flow from the right lateral ventricle into the now patent left foramen of Monro. Correspondence & reprint requests to Dr. Raz