Endoscopic endonasal odontoid resection with real-time intraoperative image-guided computed tomography: report of 4 cases.

The authors present 4 cases in which they used intraoperative CT (iCT) scanning to provide real-time image guidance during endonasal odontoid resection. While intraoperative CT has previously been used as a confirmatory test after resection, to the authors' knowledge this is the first time it has been used to provide real-time image guidance during endonasal odontoid resection. The operating room setup, as well as the advantages and pitfalls of this approach, are discussed. A mobile intraoperative CT scanner was used in conjunction with real-time craniospinal neuronavigation in 4 patients who underwent endoscopic endonasal odontoidectomy for basilar invagination. All patients underwent a successful decompression. In 3 of the 4 patients, real-time intraoperative CT image guidance was instrumental in achieving a comprehensive decompression. In 3 (75%) cases in which the right nostril was the predominant working channel, there was a tendency for asymmetrical decompression toward the right side, meaning that residual bone was seen on the left, which was subsequently removed prior to completion of the surgery. Endoscopic endonasal odontoid resection with real-time intraoperative image-guided CT scanning is feasible and provides accurate intraoperative localization of pathology, thereby increasing the chance of a complete odontoidectomy. For right-handed surgeons operating predominantly through the right nostril, special attention should be paid to the contralateral side of the resection, where there is often a tendency for residual pathology.

Contralateral supraorbital keyhole approach to medial optic nerve lesions: an anatomoclinical study.

OBJECTIVE The authors describe the supraorbital keyhole approach to the contralateral medial optic nerve and tract, both in a series of cadaveric dissections and in 2 patients. They also discuss the indications and contraindications for this procedure. METHODS In 3 cadaver heads, bilateral supraorbital keyhole minicraniotomies were performed to expose the ipsilateral and contralateral optic nerves. The extent of exposure of the medial optic nerve was assessed. In 2 patients, a contralateral supraorbital keyhole approach was used to remove pathology of the contralateral medial optic nerve and tract. RESULTS The supraorbital keyhole craniotomy provided better exposure of the contralateral superomedial nerve than it did of the same portion of the ipsilateral nerve. In both patients gross-total resections of the pathology was achieved. CONCLUSIONS The authors demonstrate the suitability of the contralateral supraorbital keyhole approach for lesions involving the superomedial optic nerve.

Hedgehog signaling pathway is active in GBM with GLI1 mRNA expression showing a single continuous distribution rather than discrete high/low clusters.

Hedgehog (Hh) signaling pathway is a valid therapeutic target in a wide range of malignancies. We focus here on glioblastoma multiforme (GBM), a lethal malignancy of the central nervous system (CNS). By analyzing RNA-sequencing based transcriptomics data on 149 clinical cases of TCGA-GBM database we show here a strong correlation (r = 0.7) between GLI1 and PTCH1 mRNA expression--as a hallmark of the canonical Hh-pathway activity in this malignancy. GLI1 mRNA expression varied in 3 orders of magnitude among the GBM patients of the same cohort showing a single continuous distribution-unlike the discrete high/low-GLI1 mRNA expressing clusters of medulloblastoma (MB). When compared with MB as a reference, the median GLI1 mRNA expression in GBM appeared 14.8 fold lower than that of the "high-Hh" cluster of MB but 5.6 fold higher than that of the "low-Hh" cluster of MB. Next, we demonstrated statistically significant up- and down-regulation of GLI1 mRNA expressions in GBM patient-derived low-passage neurospheres in vitro by sonic hedgehog ligand-enriched conditioned media (shh-CM) and by Hh-inhibitor drug vismodegib respectively. We also showed clinically achievable dose (50 µM) of vismodegib alone to be sufficient to induce apoptosis and cell cycle arrest in these low-passage GBM neurospheres in vitro. Vismodegib showed an effect on the neurospheres, both by down-regulating GLI1 mRNA expression and by inducing apoptosis/cell cycle arrest, irrespective of their relative endogenous levels of GLI1 mRNA expression. We conclude from our study that this single continuous distribution pattern of GLI1 mRNA expression technically puts almost all GBM patients in a single group rather than discrete high- or low-clusters in terms of Hh-pathway activity. That is suggestive of therapies with Hh-pathway inhibitor drugs in this malignancy without a need for further stratification of patients on the basis of relative levels of Hh-pathway activity among them.