Robot-assisted transcerebellar stereotactic approach to the posterior fossa in pediatric patients: a technical note

PURPOSE

During the last decade, there has been renewed interest in stereotactic approaches to diffuse intrinsic pontine gliomas (DIPGs) in children, due to the development of new concepts in molecular biology and management, and subsequent need for tissue sampling. Stereotactic frame-based and robot-assisted techniques are associated with reduced target error and have been incorporated into standard practice at our institution.

METHODS

Four children (age 2-7 years) underwent a robot-assisted frame-based transcerebellar approach using the Leksell G frame coupled with Renishaw's neuromate® stereotactic robot. The procedures included 3 biopsies (two brainstem tumors and one cerebellar hemispheric lesion) and 1 depth electrode implantation into a low-grade tumor remnant (ganglioglioma) of the middle cerebellar peduncle causing drug-resistant epilepsy in a young girl. Targeting was based on MRI, and in one case, 18F-FET-PET was coregistered to MRI to improve sampling accuracy. The frame was applied 180° rotated compared to standard orientation, and patients were positioned prone during surgery and stereotactic preoperative CT scan. Postoperative CT scan ruled out complications and was coregistered to preoperative MRI to check the target accuracy.

RESULTS

No complications occurred, and targeting was accurate in all cases. All tissue samplings provided proper histology; depth electrode EEG exploration was diagnostic and led subsequent resective surgery.

CONCLUSIONS

According to our experience, the transcerebellar frame-based robotic stereotactic approach to the cerebellum and the brainstem is feasible, safe, and effective even in young children.

Determination of simple carbohydrates in beer using SPME, on fiber derivatization and gas chromatography mass spectrometry

Fermentable sugars directly contribute to the sweetness of beer, whereas carbohydrates with more than four glycosyl units can be beneficial to the perception of beer in that they contribute to body or mouthfeel. GC/MS has not been widely used for the analysis of carbohydrate contents in beer. The analysis of beer by using L-SPME, on fiber derivatization with bis(trimethylsilyl) trifluoroacetamide (BSTFA) and GC-MS showed the presence of some carbohydrates (D-arabinose, -D-arabinopyranose, D-galactose, Dxylose, and D-mannose) never detected in beer. The analysis of three different types of beer showed that the presence of these carbohydrates can represent a significant part of the total amount of carbohydrates present in the beer.