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Song-tao Qi, Jun Fan, Xi-an Zhang and Jun Pan

Object

A precise understanding of the ambient cistern and its associated arachnoid membranes is helpful for accessing perimesencephalic lesions. However, few studies of the arachnoid membranes related to the ambient cistern have been published, and, additionally, some aspects of the ambient cistern also require further examination. The goal of this study was to reinvestigate and expound on the anatomical features of the cistern and membranes.

Methods

The ambient cisterns and its associated arachnoid membranes were examined in 20 adult cadaveric brains using an operative microscope.

Results

The perimesencephalic membrane is a set of inner arachnoid membranes surrounding the midbrain at the level of the tentorial incisura. It arises from the outer arachnoidal membranes covering the tentorial edge and the dorsum sellae and can be subdivided into anterior and posterior portions. The anterior membrane is actually the mesencephalic leaf of Liliequist membrane, which is divided into medial and lateral parts by the oculomotor nerve. The posterior membrane can be divided into horizontal and ascending parts. The ambient cistern is located above the perimesencephalic membrane and contains the anterior choroidal arteries, the posterior cerebral arteries, the basal vein, and sometimes the segments of the superior cerebellar arteries. It communicates with the carotid cistern, the interpeduncular cistern, the oculomotor cistern, the cerebellopontine and cerebellomesencephalic cistern, and the quadrigeminal cistern.

Conclusions

This study updates some information about the ambient cistern and its arachnoid membranes. The perimesencephalic membrane was identified and described in detail. The ambient cistern was verified to be a supratentorial cistern above the perimesencephalic membrane. The borders and contents of this cistern, as well as its relationship with adjacent cisterns, were also redefined.

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Jun Fan, Songtao Qi, Yuping Peng, Xi-an Zhang, Binghui Qiu and Jun Pan

Rathke's cleft cysts (RCCs) are benign cysts typically located in the sellar or suprasellar region; ectopic isolated lesions are extremely rare. The authors describe the case of a 25-year-old man with a giant symptomatic RCC arising primarily at the cerebellopontine angle (CPA), only the second case reported thus far. The patient presented with a 2-year history of right hearing impairment and tinnitus accompanied by vertigo and headache and a 2-week history of right facial numbness. Subsequently, he underwent total cyst removal via retrosigmoid craniotomy with a good recovery. He experienced no recurrence during a 64-month follow-up period. The possible pathogenesis, differential diagnosis, and surgical treatment of such cysts are discussed in this article. Isolated ectopic RCCs can arise from the ectopic migration of Rathke's pouch cells during the embryonic period. It is still difficult to distinguish ectopic RCCs from other cystic lesions of the CPA given the lack of specific imaging features. Aggressive resection of the cyst wall is not recommended, except when lesions do not closely adhere to adjacent structures.

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Xi-an Zhang, Song-tao Qi, Jun Fan, Guang-long Huang and Jun-xiang Peng

Object

The aim of this study was to describe the similarity of configuration between the arachnoid complex in the posterior half of the incisural space and the Liliequist membrane.

Methods

Microsurgical dissection and anatomical observation were performed in 20 formalin-fixed adult cadaver heads. The origin, distribution, and configuration of the arachnoid membranes and their relationships with the vascular structures in the posterior half of the incisural space were examined.

Results

The posterior perimesencephalic membrane and the cerebellar precentral membrane have a common origin at the tentorial edge and form an arachnoid complex strikingly resembling an inverted Liliequist membrane. Asymmetry between sides is not uncommon. If the cerebellar precentral membrane is hypoplastic on one side or both, the well-developed quadrigeminal membrane plays a prominent part in partitioning the subarachnoid space in the posterior half of the incisural space.

Conclusions

The arachnoid complex in the posterior half of the incisural space can be regarded as an inverted Liliequist membrane. This concept can help neurosurgeons to gain better understanding of the surgical anatomy at the level of the tentorial incisura.

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Jun Fan, Yuping Peng, Songtao Qi, Xi-an Zhang, Binghui Qiu and Jun Pan

Object

An assessment regarding both surgical approaches and the extent of resection for Rathke cleft cysts (RCCs) based on their locations has not been reported. The aim of this study was to report the results of a large series of surgically treated patients with RCCs and to evaluate the feasibility of individualized surgical strategies for different RCCs.

Methods

We retrospectively reviewed 87 cases involving patients with RCCs (16 intrasellar, 50 intra- and suprasellar, and 21 purely suprasellar lesions). Forty-nine patients were treated via a transsphenoidal (TS) approach, and 38 were treated via a transcranial (TC) approach (traditional craniotomy in 21 cases and supraorbital keyhole craniotomy in 17). The extent of resection was classified as gross-total resection (GTR) or subtotal resection (STR) of the cyst wall. Patients were thus divided into 3 groups according to the approach selected and the extent of resection: TS/STR (n = 49), TC/STR (n = 23), and TC/GTR (n = 15).

Results

Preoperative headaches, visual dysfunction, hypopituitarism, and diabetes insipidus (DI) resolved in 85%, 95%, 55%, and 65% of patients, respectively. These rates did not differ significantly among the 3 groups. Overall, complications occurred in 8% of patients in TS/STR group, 9% in TC/STR group, and 47% in TC/GTR group, respectively (p = 0.002). Cerebrospinal fluid (CSF) leakage (3%), new hypopituitarism (9%), and DI (6%) were observed after surgery. All CSF leaks occurred in the endonasal group, while the TC/GTR group showed a higher rate of postoperative hypopituitarism (p = 0.7 and p < 0.001, respectively). It should be particularly noted that preoperative hypopituitarism and DI returned to normal, respectively, in 100% and 83% of patients who underwent supraorbital surgery, and with the exception of 1 patient who had transient postoperative DI, there were no complications in patients treated with supraorbital surgery. Kaplan-Meier 3-year recurrence-free rates were 84%, 87%, and 86% in the TS/STR, TC/STR, and TC/GTR groups, respectively (p = 0.9).

Conclusions

It is reasonable to adopt individualized surgical strategies for RCCs based on cyst location. Gross-total resection does not appear to reduce the recurrence rate but increase the risk of postoperative complications. The endonasal approach seems more appropriate for primarily intrasellar RCCs, while the craniotomy is recommended for purely or mainly suprasellar cysts. The supraorbital route appears to be preferred over traditional craniotomy for its minimal invasiveness and favorable outcomes. The endoscopic technique is helpful for either endonasal or supraorbital surgery.

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Chao-hu Wang, Song-Tao Qi, Jun Fan, Jun Pan, Jun-Xiang Peng, Jing Nie, Yun Bao, Ya-Wei Liu, Xi’an Zhang and Yi Liu

OBJECTIVE

Nuclear β-catenin, a hallmark of active canonical Wnt signaling, can be histologically detected in a subset of cells and cell clusters in up to 94% of adamantinomatous craniopharyngioma (ACP) samples. However, it is unclear whether nuclear β-catenin–containing cells within human ACPs possess the characteristics of tumor stem cells, and it is unknown what role these cells have in ACP.

METHODS

Primary ACP cells were cultured from 12 human ACP samples. Adamantinomatous CP stem cell–like cells (CSLCs) showing CD44 positivity were isolated from the cultured primary ACP cells by performing magnetic-activated cell sorting. The tumor sphere formation, cell cycle distribution, stemness marker expression, and multidifferentiation potential of the CD44− cells and the CSLCs were analyzed.

RESULTS

Compared with the CD44− cells, the cultured human CSLCs formed tumor spheres and expressed CD44 and CD133; moreover, these cells demonstrated nuclear translocation of β-catenin. In addition, the CSLCs demonstrated osteogenic and adipogenic differentiation capacities compared with the CD44− cells. The CSLCs also displayed the capacity for tumor initiation in human–mouse xenografts.

CONCLUSIONS

These results indicate that CSLCs play an important role in ACP development, calcification, and cystic degeneration.