PMC4771866_01
(A) The patient was previously treated under the diagnosis of arachnoid cyst by partial membranectomy and cyst-subarachnoid shunt. (B) The tube previously inserted is indicated by the white arrow. (C) The patient was referred to our hospital because of the increased size of the arachnoid cyst with chronic hemorrhage. (D) Right MCA branch was adherent to the cyst wall on 3D-CTA. (E, F) Repeated intracystic hemorrhage was observed even after the large area of membranectomy on CT and MRI.
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One year after diagnosis, cyst wall fenestration and a cyst-subarachnoid shunt were performed (Fig. 1A and B). After subsequent repeated hemorrhage, shunt obstruction had led to increased intracranial pressure, and the patient was referred to our hospital (Fig. 1C). The cyst wall was adjacent to the middle cerebral artery branch in the Sylvian fissure (Fig. 1D). However, even after the surgical intervention, fresh hemorrhage continued within the cyst, and progressively increased intracranial pressure (Fig. 1E and F).
Photograph shows the organized arachnoid membrane. The membrane was hard, but bled easily. The white arrow indicates the previously placed shunt tube, and the black arrow indicates the arachnoid membrane beneath the organized membrane.
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Cyst wall resection was performed after extending the previous craniotomy (Fig. 2).
Arteriography revealed a distinct blush to the arachnoid membrane from branches of MMA. Intra-arterial embolization was performed using n-butyl cyanoacrylate against one of the feeding arteries.
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Therefore, after embolization of the middle meningeal artery with n-butyl cyanoacrylate, endoscopic irrigation was performed through the burr hole (Fig. 3).
(A) Endoscopic appearance of the second operation revealed that the fenestration of arachnoid cyst membrane was still patent, and irrigation was performed through the burr hole. (B) Coagulated blood was observed endoscopically.
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Communicating fenestration within the fresh coagulated blood was confirmed endoscopically (Fig. 4).
CT image obtained 6 weeks after the surgery demonstrated a good clinical course and no recurrent hemorrhage.
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Six weeks after the surgical intervention, regrowth of the arachnoid cyst has not been observed (Fig. 5).
Microscopically, the membrane was formed with a thin arachnoid membrane as an outer layer. Under the arachnoid membrane, a thick hyalinized and organized membrane is seen, and distinct neovascularization is observed within the layer of the organized membrane.
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The differences may have originated from the anatomical and histological differences between the arachnoid membrane and dura matter (Fig. 6).