- Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, Japan
Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, Japan
DOI:10.4103/2152-7806.102334Copyright: © 2012 Funaki T. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Funaki T, Makino Y, Arakawa Y, Hojo M, Kunieda T, Takagi Y, Takahashi JC, Miyamoto S. Arachnoid cyst of the velum interpositum originating from tela choroidea. Surg Neurol Int 13-Oct-2012;3:120
How to cite this URL: Funaki T, Makino Y, Arakawa Y, Hojo M, Kunieda T, Takagi Y, Takahashi JC, Miyamoto S. Arachnoid cyst of the velum interpositum originating from tela choroidea. Surg Neurol Int 13-Oct-2012;3:120. Available from: http://sni.wpengine.com/surgicalint_articles/arachnoid-cyst-of-the-velum-interpositum-originating-from-tela-choroidea/
Background:Arachnoid cysts originating from the velum interpositum are very rare, and their existence as a clinicopathologic entity remains controversial. We report a case of a patient with an arachnoid cyst of the velum interpositum presenting with memory disturbance, focusing on the anatomical origin of the lesion and the physiological mechanisms causing memory disturbance.
Case Description:A 65-year-old man with a large cystic lesion in the velum interpositum experienced progressive memory disturbance and enlargement of the lesion 6 months before referral to our institution. Neuropsychological evaluation on admission demonstrated severe memory disturbance. Radiological examination did not reveal hydrocephalus, but the bilateral fornices and thalami were compressed by the cyst. The patient underwent endoscopic cystoventriculostomy via the frontal horn of the right lateral ventricle through a frontal burr hole. Histopathology of the sample was consistent with that of an arachnoid cyst, and the endoscopic findings suggested that the cyst originated from the tela choroidea, which covers the velum interpositum. The symptoms resolved after surgery with significant improvement in neuropsychological test scores.
Conclusion:Arachnoid cysts of the velum interpositum are rare but distinct clinicopathologic entities that originate from the tela choroidea. The lesions can cause memory disturbance without hydrocephalus due to compression of the fornices and thalami, but this can be reversed by surgery.
Keywords: Arachnoid cyst, neuroendoscopy, velum interpositum
Velum interpositum is the space between the two layers of the tela choroidea in the roof of the third ventricle.[
We report a case of a patient with a cyst of the velum interpositum successfully treated by neuroendoscopy. We discuss the anatomical origin of the lesion, which was identified from both endoscopic findings and histopathology, as well as physiological mechanisms causing memory disturbance.
A 65-year-old male visited a medical clinic for memory disturbance. Magnetic resonance imaging (MRI) of the head revealed a cystic lesion around the velum interpositum. The symptoms worsened with enlargement of the lesion, and the patient was referred to our hospital for further examination and treatment. A neurological examination on admission revealed mild cognitive impairment with a Mini-Mental State Examination score of 22. There was no papilledema or focal neurological deficit. Further neuropsychological evaluation of memory using the Wechsler Memory Scale-Revised test[
(a) Fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) before surgery revealing reduction in glucose metabolism of the medial aspects of the cerebrum (arrows) and bilateral thalami (arrowheads). (b) FDG-PET after surgery demonstrating improvement in glucose metabolism at the regions indicated on the preoperative image
The patient underwent an endoscopic cystoventriculostomy via the lateral ventricle [
Endoscopic views. (a) View from the frontal horn of the right lateral ventricle showing a round protuberance on the septum pellucidum. The foramen of Monro, anterior septal, and thalamostriate vein are intact. (b) Small fenestration on the protuberance. (c) Semi-transparent true cyst wall under a thin ependymal membrane; the true cyst wall is held up with microforceps. (d) View of the interior of the cyst. The internal cerebral veins inferior to the cyst are seen through the semi-transparent cyst wall (arrows). Ant., anterior; For., foramen; Sept., septal; Str., striate; V., vein
The symptoms resolved immediately after surgery. MRI after surgery confirmed a significant decrease in the size of the cyst [
The velum interpositum is the space situated on the medial side of the body portion of the choroidal fissure in the roof of the third ventricle below the body of the fornix and between the superomedial surfaces of the thalami.[
Schematic illustrations showing a coronal plane of the cerebrum. Orange lines indicate the ependymal layer, while green lines indicate the embryonic pial layer. Illustration presenting the anatomic layers around the velum interpositum. (a) The velum interpositum is the space between the two layers of the tela choroidea. A small cyst originates from the upper layer of the tela choroidea. Enlargement of the cyst. (b) The cyst wall is covered with the ependymal layer, and the internal cerebral veins are shifted inferiorly due to compression by the cyst. Chor., choroid; Interposit., interpositum; Lat., lateral; Plex., plexus; Vent., ventricle
In the present case, neuroendoscopic examination revealed that the cyst wall was covered with ependymal tissue and involved the internal cerebral veins at its inferior margin, which indicates the cyst was located in the velum interpositum. Furthermore, the locational relationship between the cyst and the internal cerebral veins suggests that the cyst originated from the upper layer of the tela choroidea [
Arachnoid cysts in the ventricular system, where no arachnoid tissue exists, are a relatively well-known pathologic entity.[
Two entities are sometimes confused with arachnoid cysts of the velum interpositum. One is the cavum veli interpositi, a physiological dilatation of the velum interpositum cistern. It is a normal variant observed in premature and newborn infants, similar to the cavum septi pellucidi and cavum vergae.[
Although memory deficit is a representative cognitive symptom caused by intracranial arachnoid cysts,[
Histologic and endoscopic findings of the present case suggest that arachnoid cysts of the velum interpositum are rare but distinct clinicopathologic entities that originate from the tela choroidea covering the velum interpositum. The lesions can cause memory disturbance without hydrocephalus due to compression of the fornices and thalami, but this can be reversed by surgery.
We are grateful to Dr. Yusuke Takei for helpful advice on the histopathology.
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