Rapid intraoperative molecular genetic classification of gliomas using Raman spectroscopy.

BACKGROUND: The molecular genetic classification of gliomas, particularly the identification of isocitrate dehydrogenase (IDH) mutations, is critical for clinical and surgical decision-making. Raman spectroscopy probes the unique molecular vibrations of a sample to accurately characterize its molecular composition. No sample processing is required allowing for rapid analysis of tissue. The aim of this study was to evaluate the ability of Raman spectroscopy to rapidly identify the common molecular genetic subtypes of diffuse glioma in the neurosurgical setting using fresh biopsy tissue. In addition, classification models were built using cryosections, formalin-fixed paraffin-embedded (FFPE) sections and LN-18 (IDH-mutated and wild-type parental cell) glioma cell lines. METHODS: Fresh tissue, straight from neurosurgical theatres, underwent Raman analysis and classification into astrocytoma, IDH-wild-type; astrocytoma, IDH-mutant; or oligodendroglioma. The genetic subtype was confirmed on a parallel section using immunohistochemistry and targeted genetic sequencing. RESULTS: Fresh tissue samples from 62 patients were collected (36 astrocytoma, IDH-wild-type; 21 astrocytoma, IDH-mutated; 5 oligodendroglioma). A principal component analysis fed linear discriminant analysis classification model demonstrated 79%-94% sensitivity and 90%-100% specificity for predicting the 3 glioma genetic subtypes. For the prediction of IDH mutation alone, the model gave 91% sensitivity and 95% specificity. Seventy-nine cryosections, 120 FFPE samples, and LN18 cells were also successfully classified. Meantime for Raman data collection was 9.5 min in the fresh tissue samples, with the process from intraoperative biopsy to genetic classification taking under 15 min. CONCLUSION: These data demonstrate that Raman spectroscopy can be used for the rapid, intraoperative, classification of gliomas into common genetic subtypes.

Subclinical meningoventriculitis as a cause of obstructive hydrocephalus.

Communicating hydrocephalus may complicate infantile bacterial meningitis, typically presenting with systemic features of infection. We report a rare case of 'subclinical meningoventriculitis' causing obstructive hydrocephalus and its challenging management. A healthy 10-week-old immunocompetent male patient presented with failure to thrive and vomiting, secondary to presumed gastro-oesophageal reflux. The child was neurologically alert, afebrile with normal inflammatory markers. Progressive macrocephaly prompted an MRI confirming triventricular hydrocephalus secondary to aqueductal stenosis. An endoscopic third ventriculostomy was performed however abandoned intraoperatively due to the unexpected finding of intraventricular purulent cerebrospinal fluid. A 6-week course of intravenous ceftriaxone was commenced for Escherichia coli meningoventriculitis. However, the child was readmitted 18 days postoperatively with acute hydrocephalus requiring a ventricular washout and staged ventriculoperitoneal shunt insertion at 4 weeks. Serial head circumference measurements are paramount in the assessment of a paediatric patient. In an immunocompetent child, a subclinical fibropurulent meningoventriculitis can result in several management challenges.