A multielectrode probe in combination with an optimized stimulation protocol could provide sufficient sensitivity and specificity to act as an effective safety mechanism for preservation of the facial nerve in case of an unsafe drill distance during image-guided cochlear implantation. A minimally invasive cochlear implantation is enabled by image-guided and robotic-assisted drilling of an access tunnel to the middle ear cavity. The approach requires the drill to pass at distances below 1 mm from the facial nerve and thus safety mechanisms for protecting this critical structure are required. Neuromonitoring is currently used to determine facial nerve proximity in mastoidectomy but lacks sensitivity and specificity necessaries to effectively distinguish the close distance ranges experienced in the minimally invasive approach, possibly because of current shunting of uninsulated stimulating drilling tools in the drill tunnel and because of nonoptimized stimulation parameters. To this end, we propose an advanced neuromonitoring approach using varying levels of stimulation parameters together with an integrated bipolar and monopolar stimulating probe. An in vivo study (sheep model) was conducted in which measurements at specifically planned and navigated lateral distances from the facial nerve were performed to determine if specific sets of stimulation parameters in combination with the proposed neuromonitoring system could reliably detect an imminent collision with the facial nerve. For the accurate positioning of the neuromonitoring probe, a dedicated robotic system for image-guided cochlear implantation was used and drilling accuracy was corrected on postoperative microcomputed tomographic images. From 29 trajectories analyzed in five different subjects, a correlation between stimulus threshold and drill-to-facial nerve distance was found in trajectories colliding with the facial nerve (distance 95%) at distances to the facial nerve below 0.5 mm. However, reduction in stimulus threshold to 0.3 mA or lower resulted in a decrease of facial nerve distance detection range below 0.1 mm (>95% sensitivity). Subsequent histopathology follow-up of three representative cases where the neuromonitoring system could reliably detect a collision with the facial nerve (distance <0.1 mm) revealed either mild or inexistent damage to the nerve fascicles. Our findings suggest that although no general correlation between facial nerve distance and stimulation threshold existed, possibly because of variances in patient-specific anatomy, correlations at very close distances to the facial nerve and high levels of specificity would enable a binary response warning system to be developed using the proposed probe at low stimulation currents.

Diffusion combined with relaxation time differences were used to eliminate lipid contributions from HR-MAS spectra of biopsies impeding metabolite analysis.

Objectives The main aim of this study was to evaluate the feasibility of minimally invasive stabilization with polyaxial screws-rod using neuronavigation and to assess accuracy and safety of percutaneous drilling of screw corridors using neuronavigation in thoracolumbar spine and compare it between an experienced and a novice surgeon. Study Design Feasibility of minimally invasive polyaxial screws-rod fixation using neuronavigation was first performed in the thoracolumbar spine of two dogs. Accuracy and safety of drilling screw corridors percutaneously by two surgeons from T8 to L7 in a large breed dog using neuronavigation were established by comparing entry and exit points coordinates deviations on multiplanar reconstructions between preoperative and postoperative datasets and using a vertebral cortical breach grading scheme. Results Feasibility of minimally invasive stabilization was demonstrated. For the experienced surgeon, safety was 100% and mean (standard deviation) entry point deviations were 0.3 mm (0.8 mm) lateral, 1.3 mm (0.8 mm) ventral and 0.7 mm (1.8 mm) caudal. The exit points deviations were 0.8 mm (1.9 mm) lateral, 0.02 mm (0.9 mm) dorsal and 0.7 mm (2.0 mm) caudal. Significant difference in accuracy between surgeons was found in the thoracic region but not in the lumbar region. Accuracy and safety improvement are noted for the thoracic region when procedures were repeated by the novice. Conclusion This proof of concept demonstrates that using neuronavigation, minimally invasive stabilization with polyaxial screws-rod is feasible and safe in a large breed dog model.

Objective: To determine cutoff values for the diagnosis of atlantoaxial instability (AAI) based on cross‐sectional imaging in small‐breed dogs.Study design: Retrospective multicenter study.Sample population: Client‐owned dogs (n = 123) and 28 cadavers.Methods: Dogs were assigned to three groups: a control group, a “potentially unstable” group, and an AAI‐affected group, according to imaging findings and clinical signs. The ventral compression index (VCI), cranial translation ratio (CTR), C1‐C2 overlap, C1‐C2 angle, atlantoaxial distance, basion‐dens interval, dens‐to‐axis length ratio (DALR), power ratio, and clivus canal angles were measured on CT or T2‐weighted magnetic resonance (MR) images. Receiver operating characteristic (ROC) analysis was performed to define cutoff values in flexed (≥25°) and extended (<25°) head positions.Results: Cutoff values for the VCI of ≥0.16 in extended and ≥0.2 in flexed head positions were diagnostic for AAI (sensitivity of 100% and 100%, specificity of 94.54% and 96.67%, respectively). Cutoff values for the other measurements were defined with a lower sensitivity (75%‐96%) and specificity (70%‐97%). A combination of the measurements did not increase the sensitivity and specificity compared with the VCI as single measurement.Conclusion: Cutoff values for several imaging measurements were established with good sensitivity and specificity. The VCI, defined as the ratio between the ventral and dorsal atlantodental interval, had the highest sensitivity and specificity in both head positions.Clinical significance: The use of defined cutoff values allows an objective diagnosis of AAI in small‐breed dogs. The decision for surgical intervention, however, should remain based on a combination of clinical and imaging findings.

This report describes a case of a bronchiolar adenocarcinoma in a 6-year old alpaca mare. For the first time in an alpaca, neoplasia was classified by histopathology as a lepidic-predominant bronchiolar adenocarcinoma. The mare was referred to the Clinic for Ruminants after a 6-week period of forced breathing and weight loss. The clinical examination included complete blood count, blood chemistry, ultrasound, radiographs and a CT-scan of the thorax. A bilateral pneumothorax and several, structures within the lung parenchyma were diagnosed. Differential diagnosis included neoplasia, tuberculosis and fungal granulomas. The owner requested euthanasia due to the mare’s ongoing deterioration. At postmortem examination, the granulomatous changes in the lungs were histopathologically classified as lepidic dominant bronchiolar adenocarcinoma. Neoplastic diseases are more often seen in South American camelids compared to other farm animal species. The use of a CT scan was helpful in classifying the lung lesions and give a clear prognosis.