Xi-an Zhang

Growth patterns of craniopharyngiomas: clinical analysis of 226 patients

OBJECT Craniopharyngiomas (CPs) are rare epithelial tumors that are often associated with an enigmatic and unpredictable growth pattern. Understanding the growth patterns of these tumors has a direct impact on surgical planning and may enhance the safety of radical tumor removal. The aim of this study was to analyze the growth patterns and surgical treatment of CPs with a focus on the involvement of the hypothalamopituitary axis and the relationship of the tumor to the arachnoid membrane and surrounding structures. METHODS Clinical data from 226 consecutive patients with primary CP were retrospectively reviewed. Tumor location and the relationship of the tumor to the third ventricle floor and the pituitary stalk were evaluated using preoperative MRI and intraoperative findings. A topographic classification scheme was proposed based on the site of tumor origin and tumor development. The clinical relevance of this classification on patient presentation and outcomes was also analyzed. RESULTS The growth of CPs can be broadly divided into 3 groups based on the site of tumor origin and on tumor-meningeal relationships: Group I, infrasellar/infradiaphragmatic CPs (Id-CPs), which mainly occurred in children; Group II, suprasellar subarachnoid extraventricular CPs (Sa-CPs), which were mainly observed in adults and rarely occurred in children; and Group III, suprasellar subpial ventricular CPs (Sp-CPs), which commonly occurred in both adults and children. Tumors in each group may develop complex growth patterns during vertical expansion along the pituitary stalk. Tumor growth patterns were closely related to both clinical presentation and outcomes. Patients with Sp-CPs had more prevalent weight gain than patients with Id-CPs or Sa-CPs; the rates of significant weight gain were 41.7% for children and 16.7% for adults with Sp-CPs, 2.2% and 7.1% for those with Id-CPs, and 12.5% and 2.6% for those with Sa-CPs (p < 0.001). Moreover, patients with Sp-CPs had increased hypothalamic dysfunction after radical removal; 39% of patients with Sp-CPs, 14.5% with Id-CPs, and 17.4% with Sa-CPs had high-grade hypothalamic dysfunction in the first 2 postoperative years (p < 0.001). CONCLUSIONS The classification of CPs based on growth pattern may elucidate the best course of treatment for this formidable tumor. More tailored, individualized surgical strategies based on tumor growth patterns are mandatory to provide long-term tumor control and to minimize damage to hypothalamic structures. Differences in the distribution of growth patterns between children and adults imply that hierarchical comparison is necessary when investigating outcomes and survival across treatment paradigms in patients with CP.

Reinvestigation of the ambient cistern and its related arachnoid membranes: an anatomical study

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.

Individualized surgical strategies for Rathke cleft cyst based on cyst location.

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.

Anatomical and histological study of Liliequist's membrane: with emphasis on its nature and lateral attachments.

PurposeIn previous studies, some disagreements regarding the nature (inner or outer arachnoid membrane) and lateral boundaries (temporal uncus or tentorial edge) of Liliequist’s membrane remain. The aim was to clarify whether Liliequist’s membrane is an inner or outer arachnoid membrane, and the distribution of Liliequist’s membrane with emphasis on its lateral attachments.MethodsLiliequist’s membrane was investigated by microsurgical dissection in 24 formalin-fixed adult cadaver heads and by histological sections of sellar–suprasellar specimens from another four formalin-fixed adult cadaver heads.ResultsThe results obtained in the present study indicated that 1) Liliequist’s membrane arises from the basal arachnoid membrane and has two components: a basal part comprising a folding inner layer of the arachnoid mater and an attaching part consisting of accumulated arachnoid trabeculae; 2) similar histological features are also present in other inner arachnoid membranes with attachments on basal arachnoid membrane, demonstrating Liliequist’s membrane is an inner arachnoid membrane; 3) laterally, Liliequist’s membrane attaches to the anterior tentorial edge constantly and to the mesial temporal uncus in more than half; 4) the oculomotor nerve courses above Liliequist’s membrane and is fixed on Liliequist’s membrane by the oculomotor membrane, which can also attach on temporal uncus and should be differentiated from the true temporal attachments of Liliequist’s membrane.ConclusionLiliequist’s membrane is an inner rather than outer arachnoid membrane. Understanding of its individual variation and topographic relationships with surrounding neurovascular and arachnoid structures is important for neurosurgical practice.

The distribution of arachnoid membrane within the velum interpositum

BackgroundThere is as yet little knowledge as to the arachnoid architecture within the velum interpositum. The aim of this study was to clarify the distribution of the arachnoid membrane within the velum interpositum and its relationship with the arachnoid envelope over the pineal region.MethodsIn seven adult cadaver heads, histological sections of the third ventricle roof, stained with Masson’s trichrome stains, were studied under light microscopy.ResultsWithin the velum interpositum, there are two arachnoid layers. The dorsal layer of arachnoid membrane envelops the internal cerebral veins and fixes them to the surrounding tela choroidea as well as the ventral arachnoid layer. The ventral layer of arachnoid membrane is a direct anterior extension of the arachnoid envelope over the pineal region and covers the midline inferior layer of tela choroidea. Both arachnoid layers end near the foramen of Monro.ConclusionsThe membranous roof of the third ventricle comprises two layers of the tela choroidea and two arachnoid layers. These two arachnoid layers are derived from the arachnoid envelope over the pineal region.

Arachnoid membranes in the posterior half of the incisural space: an inverted Liliequist membrane-like arachnoid complex.

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.

An isolated primary Rathke's cleft cyst in the cerebellopontine angle

Rathkes 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 Rathkes 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.

Risk score for the prediction of severe obesity in pediatric craniopharyngiomas: relative to tumor origin

BackgroundWe aimed to develop a risk score to improve the prediction of severe obesity in pediatric craniopharyngiomas (PCs).MethodsOverall, 612 consecutive PCs were prospectively enrolled from six hospitals. Data from 404 participants were analyzed. Participants from three of the six hospitals (n=290) were used to develop a risk score. External validation of the developed risk score was conducted using the participants from the other three hospitals (n=114). Sequential logistic regression was used to develop and validate the risk score. The c statistic and a calibration plot were used to assess the discrimination and calibration of the proposed risk score.ResultsThe overall frequency of severe obesity was 16.1% (65/404). The risk score employed a scale of 0–16 and demonstrated good discriminative power, with an optimism-corrected c statistic of 0.820. Similar results were obtained from external validation, with a c statistic of 0.821. The risk score showed good calibration, with no apparent over- or under-prediction observed in the calibration plots.ConclusionsThis novel risk score is a simple tool that can help clinicians assess the risk of severe obesity in PCs, thereby helping to plan and initiate the most appropriate disease management for these patients in time.