[A case of the development of cavum vergae after head trauma].

We report a case of the development of cavum septi pellucidi and cavum Vergae after head trauma in a 29-year-old female patient. After the accident, cavum septi pellucidi and cavum Vergae gradually expanded. Using magnetic resonance imaging, we followed up the patient for 33 months after the head trauma. Preoperatively, metrizamide CT cisternography was performed in order to investigate CSF flow between the cavum septi pellucidi/cavum Vergae and the subarachnoid space. Using neuroendoscopy, we succeeded in opening the wall of the cavum septi pellucidi via anterior horn of the right lateral ventricle. Cystography was performed during the operation. The volume of the cavum septi pellucidi/cavum Vergae decreased remarkably. In this case, our CSF flow studies revealed that CSF flowed into the posterior part of the cavum Vergae from the third ventricle and did not flow backward to the third ventricle. Therefore, we considered that the development of cavum septi pellucidi/cavum Vergae was related to a one-way valve mechanism between the posterior part of the cavum Vergae and the third ventricle.