High-resolution LC-MS/MS tandem mass spectra-based machine learning models are constructed to address the analytical challenge of identifying unknown controlled substances and new psychoactive substances (NPS’s). Using a training set comprised of 770 LC-MS/MS barcode spectra (with binary entries 0 or 1) obtained generally by high-resolution mass spectrometers, three classification machine learning models were generated and evaluated. The three models are artificial neural network (ANN), support vector machine (SVM), and k-nearest neighbor (k-NN) models. In these models, controlled substances and NPS’s were classified into 13 subgroups (benzylpiperazine, opiate, benzodiazepine, amphetamine, cocaine, methcathinone, classical cannabinoid, fentanyl, 2C series, indazole carbonyl compound, indole carbonyl compound, phencyclidine, and others). Using 193 LC-MS/MS barcode spectra as an external test set, accuracy of the ANN, SVM, and k-NN models were evaluated as 72.5%, 90.0%, and 94.3%, respectively. Also, the hybrid similarity search (HSS) algorithm was evaluated to examine whether this algorithm can successfully identify unknown controlled substances and NPS’s whose data are unavailable in the database. When only 24 representative LC-MS/MS spectra of controlled substances and NPS’s were selectively included in the database, it was found that HSS can successfully identify compounds with high reliability. The machine learning models and HSS algorithms are incorporated into our home-coded AI-SNPS (artificial intelligence screener for narcotic drugs and psychotropic substances) standalone software that is equipped with a graphic user interface. The use of this software allows unknown controlled substances and NPS’s to be identified in a convenient manner.

Background and ObjectivesZZThis study reviewed our experience and outcomes of surgery via transcrusal approach to the skull base lesions. Subjects and MethodZZWe performed transcrusal approach technique on five patients with skull base lesions (Cavernous malformation, Petroclival meningioma, Craniopharyngioma, Anaplastic astrocytoma, and Trigerminal epidermoid cyst) aiming at preserving hearing. Preand post-operative pure tone audiometry (PTA) and caloric test were performed in all patients. The transcrusal approach technique was performed as reported in the previous references. The approach included trephination of the superior and posterior semicircular canals from the ampullae to the common crus. The main outcome of this study was preserving hearing and the vestibular function after surgery, which was determined by PTA and caloric test. ResultsZZThe average diameter of skull base lesion of the five patients was 3.68 cm. The mean follow up period was 114.2 days. The pre-operative mean PTA of five patients was 11 dB. The mean PTA of five patients within seven days after surgery was 28 dB. The last measured mean PTA was 29.8 dB. The pre and post-operative caloric results measured revealed vestibular function deficit in all of the patients after surgery (mean decreased value: 64%). All patients were stable during the surgery. Complications included two cerebrospinal fluid leak (40%) and one cranial VI nerve deficit (20%). ConclusionZZTranscrusal approach is a method that can simultaneously preserve hearing and afford enough exposure of the skull base lesion if appropriately combined with other transcranial approach. We performed transcrusal approach targeting skull base lesion with hearing preservation, and we found excellent hearing result with this technique.