Spectral characteristics of subthalamic nucleus local field potentials in Parkinson's disease: Phenotype and movement matter.

Parkinson's disease (PD) is clinically heterogeneous across patients and may be classified in three motor phenotypes: tremor dominant (TD), postural instability and gait disorder (PIGD), and undetermined. Despite the significant clinical characterization of motor phenotypes, little is known about how electrophysiological data, particularly subthalamic nucleus local field potentials (STN-LFP), differ between TD and PIGD patients. This is relevant since increased STN-LFP bandpower at α-ß range (8-35 Hz) is considered a potential PD biomarker and, therefore, a critical setpoint to drive adaptive deep brain stimulation. Acknowledging STN-LFP differences between phenotypes, mainly in rest and movement states, would better fit DBS to clinical and motor demands. We studied this issue through spectral analyses on 35 STN-LFP in TD and PIGD patients during rest and movement. We demonstrated that higher ß2 activity (22-35 Hz) was observed in PIGD only during rest. Additionally, bandpower differences between rest and movement occurred at the α-ß range, but with different patterns as per phenotypes: movement-induced desynchronization concerned lower frequencies in TD (10-20 Hz) and higher frequencies in PIGD patients (21-28 Hz). Finally, when supervised learning algorithms were employed aiming to discriminate PD phenotypes based on STN-LFP bandpower features, movement information had improved the classification accuracy, achieving peak performances when TD and PIGD movement-induced desynchronization ranges were considered. These results suggest that STN-LFP ß-band encodes phenotype-movement dependent information in PD patients.

A hybrid simulation model for pre-operative planning of transsphenoidal encephalocele.

Congenital transsphenoidal encephalocele (CTE) surgical correction is a challenging procedure. Although rare, this anomaly, characterized with neural herniation elements, including the pituitary gland or optic pathway through the sphenoid bone with anatomical alteration, can be presented in many different ways and should be individually analyzed. Significant advances in medical technology and the 3D models may simulate the complex anatomical relations of the human body. Nowadays, medical education relies on the availability of standardized materials that can reliably emulate human anatomy. Therefore, realistic anatomical models have become an alternative for cadavers or animal specimens. In this technical note, the authors present a new technique to create personalized models that combine 3D printing, molding, and casting to create an anatomically and tactilely realistic model based on magnetic resonance and computerized tomography images. Produced from different silicon types, the model recreated the anatomic alterations precisely, allowing a multidisciplinary team to determine the adequate surgical approach for this patient. We describe a case of congenital transsphenoidal encephalocele of a 3-year-old boy, whose surgical correction was planned using a hybrid model. The technical description of the model is given in detail. This new hybrid model allowed a detailed discussion of the surgical approach aspects by having tissues of different consistencies and resistances and a very high prediction rate. This approach may allow a reduction in surgery time and possible complications after operative procedures.