Infratemporal Fossa Vascular Anatomy Pertinent to Percutaneous Access to the Foramen Ovale for Treatment of Trigeminal Neuralgia: A Comparison of Cadaveric Dissection and Computed Tomography Analysis.

BACKGROUND: Trigeminal neuralgia may be treated via percutaneous access to the foramen ovale (FO). Vascular complications associated with the needle trajectory can result in serious morbidity and mortality. This study aimed to correlate the vascular relationships of the FO at the skull base via cadaveric dissections and computed tomography (CT). METHODS: Two fresh cadaver heads were injected with red and blue latex to delineate arteries and veins. Neck and infratemporal fossa dissections were carried out to delineate the vascular relationships of the FO. High-resolution head CT images of adult patients undergoing neurosurgical evaluations or procedures were analyzed for distances and sizes of skull base foramina in the infratemporal fossa. RESULTS: Three infratemporal fossa dissections (2 cadaveric specimens) were performed. Mean distance of FO to internal carotid artery was 2.4 ± 0.12 cm, and mean distance of FO to middle meningeal artery was 0.8 ± 0.16 cm. Head CT images of 52 patients (104 sides) with 1-mm axial slice thickness were analyzed. Area of the FO was 31.1 ± 9.6 mm2. Distance of FO to internal carotid artery was 1.70 ± 0.31 cm, and distance of FO to middle meningeal artery was 0.73 ± 0.61 cm. CONCLUSIONS: Cadaveric delineation of vascular structures in the infratemporal fossa correlates with head CT imaging and may be used to accurately plan percutaneous access to the FO. Inadvertent puncture of the extracranial internal carotid artery is nearly impossible with good technique. The most likely source of percutaneous vascular injury is the middle meningeal artery and distal branches of the maxillary artery.

Robotic-Navigated Percutaneous Pedicle Screw Placement Has Less Facet Joint Violation Than Fluoroscopy-Guided Percutaneous Screws.

OBJECTIVE: To directly compare robotic-versus fluoroscopy-guided percutaneous pedicle screw (PPS) placement in thoracolumbar spine trauma with a focus on clinically acceptable pedicle screw accuracy and facet joint violation (FJV). METHODS: A retrospective chart review assessed 37 trauma patients undergoing percutaneous thoracic and/or lumbar fixation. Postoperative computed tomography images were reviewed by authors blinded to surgical technique who assessed pedicle screw trajectory accuracy and FJV frequency. RESULTS: Seventeen patients underwent placement of 143 PPS with robotic assistance (robot group), compared with 20 patients receiving 149 PPS using fluoroscopy assistance (control group). Overall, the robot cohort demonstrated decreased FJV frequency of 2.8% versus 14.8% in controls (P = 0.0003). When further stratified by level of surgery (i.e., upper thoracic, lower thoracic, lumbar spine), the robot group had FJV frequencies of 0%, 3.2%, and 3.7%, respectively, compared with 17.7% (P = 0.0209), 14.3% (P = 0.0455), and 11.9% (P = 0.2340) in controls. The robot group had 84.6% clinically acceptable screw trajectories compared with 81.9% in controls (P = 0.6388). Within the upper thoracic, lower thoracic, and lumbar regions, the robot group had acceptable screw trajectories of 66.7%, 87.1%, and 90.7%, respectively, compared with 58.8% (P = 0.6261), 91.1% (P = 0.5655), and 97.6% (P = 0.2263) in controls. CONCLUSIONS: There was no significant difference in clinically acceptable screw trajectory accuracy between robotic versus fluoroscopy-guided PPS placement. However, the robot cohort demonstrated a statistically significantly decreased FJV overall and specifically within the thoracic spine region. Use of robotic technology may improve radiographic outcomes for a subset of patients or spine surgeries.

Burr-Hole Evacuation of an Acute Epidural Hematoma using the Artemis Neuroevacuation Device With Flexible Endoscopic Visualization: 2-Dimensional Operative Video.

Minimally invasive (MIS) endoscopic burr-hole evacuation of both acute and subacute subdural hematomas (SDHs) has been demonstrated as a way to avoid large craniotomies and additional morbidity, particularly for patients who are poor surgical candidates.1,2 Although generally safe and effective, there are risks of complications including SDH recurrence or new hemorrhage including epidural hematoma (EDH).3,4 Acute intraparenchymal hemorrhage has also been successfully treated using MIS endoscopic techniques with the assistance of aspiration devices; however, acute EDHs generally still necessitate a craniotomy for evacuation, nullifying many of the advantages of burr-hole craniostomy.5,6 In this surgical video, we demonstrate-to our knowledge-the first case of endoscopic burr-hole evacuation of an acute EDH using an Artemis Neuro Evacuation device (Penumbra, Alameda, CA). We present the case of a 40 year-old man with a left anterior middle cranial fossa arachnoid cyst who developed a traumatic left subacute SDH and hemorrhage into the cyst. He underwent burr-hole craniostomy for endoscopic evacuation of subacute SDH, evacuation of hemorrhage within the cyst, and fenestration of arachnoid cyst. On postoperative day 2, he developed an acute left EDH with midline shift. An Artemis device was inserted into 1 of the pre-existing burr-holes and used to evacuate the acute EDH with direct visualization from a flexible endoscope inserted into the second burr-hole. The patient did well, was discharged 2 days later, and demonstrated complete resolution of hemorrhage 5 weeks post-procedure. The video also provides a brief background on arachnoid cysts, their association with hemorrhage, and MIS techniques for hemorrhage evacuation.7-12 There is no identifying information in the video. The patient provided informed consent for both procedures (Video 1).

Retrospective Assessment of the Use of Liposomal Bupivacaine in Lumbar Fusions in Immediate Postoperative Hospital Care.

BACKGROUND: Liposomal bupivacaine (LB) is approved by the U.S. Food and Drug Administration for administration into surgical sites for postsurgical analgesia. The liposomal formulation allows for sustained effects up to 72 hours. METHODS: A retrospective study assessed patients undergoing lumbar interbody surgery. Visual analog scale pain scores and amount of opioids consumed were recorded at 12-hour intervals for 72 hours postoperatively, as were patterns of discharge and hospital length of stay (LOS). RESULTS: A total of 122 patients (97 LB vs. 25 control group) were reviewed. Median LOS was shorter in the LB cohort compared with controls (1.94 vs. 3.08 days, respectively; P = 0.0043). When assessing the percentage of discharges between groups at 12-hour intervals, there were significantly more discharges in the LB cohort at 36-48 hours (P = 0.0226), and no differences elsewhere. There was a decrease in intravenous opioids consumed at 48-60 hours in the LB cohort compared with controls (P = 0.0494), a difference not detected at other time points or with oral or total opioids. Mean visual analog scale scores were significantly higher in the LB cohort compared with controls at 0-12 hours (5.2 vs. 3.9, respectively; P = 0.0079), but insignificantly different subsequently up to 72 hours. The LB cohort and controls were not significantly different in total amount of opioids consumed, overall pain scores, or regarding how the opioid amount consumed or pain scores changed over time. CONCLUSIONS: The use of LB in lumbar interbody fusion decreases patients' LOS but has little effect on reducing overall pain scores or opioid use in the 72-hour postoperative hospital period.

Low-temperature control of nanoscale morphology for high performance polymer photovoltaics.

Understanding and controlling nanoscale morphology is crucial to the performance of polymer bulk heterojunction solar cells, as well as other optoelectronic devices such as polymer light-emitting diodes, field-effect transistors, and sensors. In photovoltaic devices, optimum blend morphologies must be commensurate with the nanometer length scales of exciton diffusion and charge separation. We report on a generally applicable method of optimizing the phase segregation in polymer-polymer bulk heterojunctions based on tuning mixtures of low and high boiling point solvents. We have characterized the resulting blend morphologies with nanometer resolution using a transient absorption technique that probes the distribution of paths traveled by the excitons themselves prior to generating charges at an interface. Photovoltaic efficiencies are accounted for in terms of exciton diffusion, geminate pair separation, and polymer ordering, all of which are sensitive to the nanoscale morphology determined by the composition of the solvent mixture.

Auditory responses in the cochlear nucleus of awake mustached bats: precursors to spectral integration in the auditory midbrain.

In the cochlear nucleus (CN) of awake mustached bats, single- and two-tone stimuli were used to examine how responses in major CN subdivisions contribute to spectrotemporal integrative features in the inferior colliculus (IC). Across CN subdivisions, the proportional representation of frequencies differed. A striking result was the substantial number of units tuned to frequencies <23 kHz. Across frequency bands, temporal response patterns, latency, and spontaneous discharge differed. For example, the 23- to 30-kHz representation, which comprises the fundamental of the sonar call, had an unusually high proportion of units with onset responses (39%) and low spontaneous rates (53%). Units tuned to 58-59 kHz, corresponding to the sharply tuned cochlear resonance, had slightly but significantly longer latencies than other bands. In units tuned to frequencies >30 kHz, 31% displayed a secondary excitatory peak, usually between 10 and 22 kHz. The secondary peak may originate in cochlear mechanisms for some units, but in others it may result from convergent input onto CN neurons. In 20% of units tested with two-tone stimuli, suppression of best frequency (BF) responses was tuned at least an octave below BF. These properties may underlie similar IC responses. However, other forms of spectral interaction present in IC were absent in CN: we found no facilitatory combination-sensitive interactions and very few combination-sensitive inhibitory interactions of the dominant IC type in which inhibition was tuned to 23-30 kHz. Such interactions arise above CN. Distinct forms of spectral integration thus originate at different levels of the ascending auditory pathway.

Projection to the inferior colliculus from the basal nucleus of the amygdala.

This report describes a projection from the amygdala, a forebrain center mediating emotional expression, to the inferior colliculus (IC), the midbrain integration center of the ascending auditory system. In the IC of mustached bats (Pteronotus parnellii) and pallid bats (Antrozous pallidus), we placed deposits of retrograde tracers at physiologically defined sites and then searched for retrogradely labeled somata in the forebrain. Labeling was most sensitive in experiments using cholera toxin B-subunit as tracer. We consistently observed retrograde labeling in a single amygdalar subdivision, the magnocellular subdivision of the basal nucleus (Bmg). The Bmg is distinctive across mammals, containing the largest cells in the amygdala and the most intense acetylcholinesterase staining. Labeled amygdalar cells occurred ipsilateral and contralateral to IC deposits, but ipsilateral labeling was greater, averaging 72%. Amygdalar labeling was observed after tracer deposits throughout the IC, including its central nucleus (ICC). In comparison, labeling in the auditory cortex (layer V) was heavily ipsilateral (averaging 92%). Cortical labeling depended on the location of IC deposits: dorsomedial deposits resulted in the most labeled cells, whereas ventrolateral deposits labeled few or no cortical cells. Cortical labeling occurred after several deposits in the ICC. Across experiments, the average number of labeled cells in the amygdala was similar to that in the auditory cortex, indicating that the amygdalocollicular projection is significant. The results demonstrate a direct, widespread projection from the basal amygdala to the IC. They also suggest the presence of a rapid thalamoamygdalocollicular feedback circuit that may impose emotional content onto processing of sensory stimuli at a relatively low level of an ascending sensory pathway.