Sphenoid Sinus Mucosal Flap after Transsphenoidal Surgery-A Systematic Review

Background and Objectives: Skull base reconstruction is a crucial step during transsphenoidal surgery. Sphenoid mucosa is a mucosal membrane located in the sphenoid sinus. Preservation and lateral shifting of sphenoid mucosa as sphenoid mucosal flap (SMF) during the transsphenoidal exposure of the sella may be important for later closure. This is the first systematic review to evaluate the utility of sphenoid mucosal flap for sellar reconstruction after transsphenoidal surgery. Materials and Methods: A systematic literature search was performed in January 2023: Cochrane, EMBASE, PubMed, Scopus, and Web of Science. The following keywords and their combinations were used: "sphenoid mucosa", "sphenoid sinus mucosa", "sphenoid mucosal flap", "sphenoid sinus mucosal flap". From a total number of 749 records, 10 articles involving 1671 patients were included in our systematic review. Results: Sphenoid sinus mucosa used to be applied for sellar reconstruction as either a vascularized pedicled flap or as a free flap. Three different types of mucosal flaps, an intersinus septal flap, a superiorly based flap and an inferiorly based flap, were described in the literature. Total SMF covering compared to partial or no SMF covering in sellar floor reconstruction resulted in fewer postoperative CSF leaks (p = 0.008) and a shorter duration of the postoperative lumbar drain (p = 0.003), if applied. Total or partial SMF resulted in fewer local complications (p = 0.012), such as fat graft necrosis, bone graft necrosis, sinusitis or fungal infection, in contrast to no SMF implementation. Conclusions: SMF seems to be an effective technique for skull base reconstruction after transsphenoidal surgery, as it can reduce the usage of avascular grafts such as fat along with the incidence of local complications, such as fat graft necrosis, bone graft necrosis, sinusitis and fungal infection, or it may improve the sinonasal quality of life by maintaining favorable wound healing through vascular flap and promote the normalization of the sphenoid sinus posterior wall. Further clinical studies evaluating sphenoid mucosal flap preservation and application in combination with other techniques, particularly for higher-grade CSF leaks, are required.

External validation of the Chicago Chiari Outcome Scale in adults with Chiari malformation type I

OBJECTIVE

The Chicago Chiari Outcome Scale (CCOS) serves as a standardized clinical outcome evaluation tool among patients with Chiari malformation type I (CM-I). While the reliability of this scale has been proven for pediatric patients, the literature lacks CCOS validation when used solely in adults. Therefore, this study aimed to determine the validity of the CCOS in an external cohort of adult patients.

METHODS

The authors retrospectively analyzed the medical records of symptomatic patients with CM-I who underwent posterior fossa decompression between 2010 and 2018 in six neurosurgical departments. Each patient was clinically assessed at the latest available follow-up. Gestalt outcome was determined as improved, unchanged, or worsened compared with the preoperative clinical state. Additionally, the CCOS score was calculated for each patient based on the detailed clinical data. To verify the ability of the CCOS to determine clinical improvement, the area under the receiver operating characteristic (AUROC) curve was evaluated. A logistic regression analysis using all four components of the CCOS (pain symptoms, nonpain symptoms, functionality, and complications) was performed to establish predictors of the improved outcome.

RESULTS

Seventy-five individuals with a mean age of 42 ± 15.32 years were included in the study. The mean follow-up duration was 52 ± 33.83 months. Considering gestalt outcome evaluation, 41 patients (54.7%) were classified as improved, 24 (32%) as unchanged, and 10 (13.3%) as worsened. All patients with a CCOS score of 14 or higher improved, while all those with a CCOS score of 8 or lower worsened. The AUROC was 0.986, suggesting almost perfect accuracy of the CCOS in delineating clinical improvement. A CCOS score of 13 showed high sensitivity (0.93) and specificity (0.97) for identifying patients with clinical improvement. Additionally, a meaningful correlation was found between higher CCOS scores in each component and better outcomes. Patient stratification by total CCOS score showed that those categorized as improved, unchanged, and worsened scored prevalently between 13 and 16 points, 10 and 12 points, and 4 and 9 points, respectively.

CONCLUSIONS

In this adult cohort, the CCOS was found to be almost perfectly accurate in reflecting postoperative clinical improvement. Moreover, all four CCOS components (pain symptoms, nonpain symptoms, functionality, and complications) significantly correlated with patient clinical outcomes.

Cystic versus non-cystic silent corticotrophic adenomas: clinical and histological analysis of 62 cases after microscopic transsphenoidal surgery-a retrospective, single-center study

Silent corticotrophic adenomas (SCAs) represent a rare group of non-functioning adenomas with a potentially aggressive clinical course. Cystic component is a very common finding among SCAs, but its clinical relevance has not yet been investigated. The aim of this study was to analyze clinical features of cystic and non-cystic SCAs, perioperative complications after microscopic transsphenoidal surgery, clinical outcome after first and repeat surgery along with risk factors for recurrence. We conducted a retrospective analysis of 62 silent corticotrophic adenomas treated at our university medical center via microscopic transsphenoidal surgery between January 2008 and July 2019. Parameters investigated included histology, invasiveness, intratumoral haemorrhage or cystic component on MRI, perioperative alteration of visual field, tumor size, pre- and postoperative ACTH, FSH, GH, LH, TSH, prolactin, cortisol, free T4, free T3, IGF-1, estrogen and testosterone levels, perioperative complications, neoadjuvant and adjuvant therapy along with clinical outcomes. A total of 62 patients were analyzed. The mean follow up was 28.3 months. Tumors with a cystic component occur statistically significant more often among male than non-cystic (80.6% vs. 44.4%, p = 0.02) and display lower rates of cavernous sinus invasion and sphenoid sinus invasion were significantly lower for cystic lesions comparing to non-cystic tumors (42.3% vs. 69.4%, p = 0.04 and 3.8% vs. 47.2%, p < 0.001). GTR after MTS was not statistically significant higher by cystic SCAs (80% vs. 57.1%, p = 0.09). Cystic lesions were also associated with higher risk of hyperprolactinemia (19.4% vs. 2.8%, p = 0.02) and only densely granulated cystic SCAs presented with preoperative intratumoral hemorrhage (19.2% vs. 0%, p = 0.01). Mean duration of first surgery was significantly shorter for cystic SCAs (71.6(± 18.7) vs. 94.8(± 31.1) minutes, p = 0.01). Preoperative pituitary insufficiency (25% vs. 16.7%, p = 0.49), intraoperative CSF space opening (21.1% vs. 37.5%, p = 0.32), along with postoperative new pituitary insufficiency (15% vs. 10%, p = 0.67) or diabetes insipidus/SIADH (10% vs. 13.3%, p > 0.99) with histological markers such as Ki67 (21.1% vs. 13.8%, p = 0.70) and p53 expression (6.3% vs. 0%, p = 0.39) as well as mitotic rate (5.3% vs. 10.3%, p > 0.99) were comparable between both groups. The presence of cystic component did not affect the tumor recurrence (10% vs. 16%, p = 0.68). Mean duration of surgery was first surgeries was not statistically shorter than repeat surgeries (85.4 ± 29.1 vs. 93.8 ± 28 min, p = 0.15). Patients undergoing first surgery had a higher probability of gross total resection (74.4% vs. 30%, p = 0.01) and lower probability of intraoperative CSF space opening (26% vs. 58.3%, p = 0.04) as well as a lower rate of preoperative anterior pituitary insufficiency (20% vs. 58.3%, p = 0.01). The incidence of new postoperative anterior pituitary insufficiency (10% vs. 0%, p = 0.57) and transient diabetes insipidus/SIADH (12% vs. 8.3%, p > 0.99) between those groups were comparable. No statistical difference was observed between patients with remission and with recurrent tumor regarding cortisol and ACTH levels, incidence of different histological subgroups, invasively growing tumors and lesions with cystic components as well as the percentage of cases with increased Ki67 proliferation index, p53 expression and mitotic indices. Our study presents one of the largest available cohorts of SCAs after microscopic transsphenoidal surgery and first clinical analysis of cystic versus non-cystic SCAs so far. We also performed the first comparison of index and repeat surgeries for this tumor entity. Cystic tumors presented with characteristic clinical aspects like male predominance, higher risk of hyperprolactinemia as well as lower rates of cavernous sinus and sphenoid sinus invasion comparing to non-cystic lesions. Mean duration of first surgery was significantly shorter for cystic SCAs. Moreover preoperative intratumoral hemorrhage had 100% specificity and 60% sensitivity for densely granulated cystic SCAs. All these clinical hallmarks may suggest a novel subgroup of SCAs with distinct clinical and biological features, however further clinical and molecular investigations are required. Second surgeries are associated with a higher incidence of preoperative pituitary insufficiency, and a higher risk of subtotal resection, and a higher probability of CSF space opening intraoperatively compared to first surgeries. On the other hand, the risk of new postoperative pituitary insufficiency was higher after first surgeries. In our cohort of patients, no prognostic factor for recurrence among histological diagnosis, Ki67-proliferation index, p53 expression, number of mitoses, invasive growth or cystic lesions for SCAs could be detected.

ETMR-02. Overexpression of Lin28A in neural progenitor cells in vivo does not lead to brain tumor formation but results in reduced spine density

The RNA binding protein LIN28A is a stem- and progenitor marker and one of the factors necessary to induce pluripotent stem cells. An overexpression of LIN28A has been identified in malignant brain tumors called embryonal tumors with multilayered rosettes (ETMR) but its specific role during brain development remains largely unknown. Radial glia cells of the ventricular zone (VZ) are proposed as a cell of origin for ETMR. We asked whether an overexpression of LIN28A in such cells might affect brain development or result in the formation of brain tumors. Constitutive overexpression of LIN28A in hGFAP-cre::lsl-Lin28A (GL) mice led to a transient increase of proliferation in the cortical VZ at embryonic stages but no postnatal brain tumor formation. Postnatally, GL mice displayed a pyramidal cell layer dispersion of the hippocampus and altered spine and dendrite morphology, including reduced dendritic spine densities in the hippocampus and cortex. GL mice displayed hyperkinetic activity and differential quantitative MS-based proteomics revealed altered time dependent molecular functions regarding mRNA processing and spine morphogenesis. Phosphoproteomic analyses indicated a downregulation of mTOR pathway modulated proteins such as Map1b being involved in microtubule dynamics within a crosstalk of Gsk3b/Rho-Rac/Map1b signaling. In conclusion, we show that Lin28A overexpression transiently increases proliferation of neural precursor cells but it is not sufficient to drive brain tumors in vivo. In contrast, Lin28A impacts on protein abundancy patterns related to spine morphogenesis and phosphorylation levels of proteins involved in microtubule dynamics, resulting in decreased spine densities of neurons in the hippocampus and cortex as well as in altered behavior. Our work provides new insights into the role of LIN28A for neuronal morphogenesis and development and may reveal future targets for treatment of ETMR patients.

OTHR-19. Disordered cell migration in the cerebral cortex caused by Lin28A overexpression and Wnt pathway activation in neural precursor cells

LIN28A overexpression and mutations of the Wnt pathway gene CTNNB1 have been described in rare malignant brain tumors of early childhood. In order to investigate the interplay of the oncogenic proteins Lin28A and Ctnnb1 during embryonal brain development, we overexpressed these components in neural progenitor cells in vivo. The sole overexpression of either Lin28A, stabilized Ctnnb1 (Ctnnb1Δex3) or the combination of both in hGFAP-positive forebrain precursor cells did not lead to brain tumor formation but resulted in distinct phenotypes in the cerebral cortex during embryonal development. The hGFAP-cre::IsI-Lin28A (GL) mouse model showed transiently increased proliferation in the cerebral ventricular zone and proper isocortical layering. hGFAP-cre::Ctnnb1Δex3fl/+ (GB) and hGFAP-cre::Ctnnb1Δex3fl/+::IsI-Lin28A (GBL) mice developed a hydrocephalus and showed disturbed cortical layering. GB mice displayed cerebral hypoplasia with a thinned cortex, while the GBL cortices showed variable thickness. Immunostainings with the pial marker Laminin and dendritic marker Map2c revealed a porous pia mater and aggregations of neurons above the pial border in the GBL model at embryonal day 14 (E14.5). At later embryonal stage (E18.5), the GBL model showed also large blood vessels located in deeper cortical layers. Proteome analyses of GB and GBL cortices revealed decreased abundance of the Lissencephaly associated component Reelin-receptor Lrp8 compared to hGFAP-cre control mice. Additionally, we found 92 proteins, which were altered specifically in the GBL mouse model. These results indicate that the co-expression of Lin28A and Ctnnb1Δex3 in neural precursor cells does not lead to brain tumor formation but results in neuronal migration disturbances with ectopic neurons in the subarachnoid area. Whereas the GB phenotype is reminiscent of human lissencephaly type I, GBL brain morphology showed similarities to neuronal overmigration observed in the migration disorder of human Cobblestone (Type II) Lissencephaly.

Internal carotid artery false aneurysm as a fatal complication of transsphenoidal surgery

False aneurysm of internal carotid artery (ICA) is a rare but serious vascular complication observed after transsphenoidal pituitary surgery. Here, we present a 41-year-old woman with a pseudoaneurysm in the ophthalmic¹ segment of the left ICA after exoscopic transsphenoidal pituitary surgery. The initially uneventful procedure was complicated by a subarachnoidal hemorrhage 10 days after the surgery, which was confirmed by cranial computed tomography scan. The emergency angiography revealed a pseudoaneurysm of the ophthalmic¹ part of the left ICA. Despite repeated endovascular treatments with a flow diverter and coiling, the patient experienced a re-bleeding with consecutive vasospasms, occlusion hydrocephalus and finally bifrontal intracerebral hemorrhage with fatal outcome. As a conclusion in irregular post-operative courses with for example headache, a post-operative magnetic resonance imaging with vessel presentation using TOF sequence and contrast-enhanced MRA might be recommended in order to detect a possible pseudoaneurysm in an early stage.