The use of a fluorine mass balance to demonstrate the mineralization of PFAS by high frequency and high power ultrasound.

High-frequency ultrasound (sonolysis) has been shown as a practical approach for mineralizing PFAS in highly concentrated PFAS waste. However, a fluorine mass balance approach showing complete mineralization for ultrasound treatment has not been elucidated. The impact of ultrasonic power density (W/L) and the presence of co-occurring PFAS on the degradation of individual PFAS are not well understood. In this research, the performance of a 10L sonochemical reactor was assessed for treating synthetic high-concentration PFAS waste with carboxylic and sulfonic perfluoroalkyl surfactants ranging in chain length from four to eight carbons at three different initial concentrations: 6, 55, 183 µM. The mass balance for fluorine was performed using three analytical techniques: triple quadrupole liquid chromatography-mass spectrometry, a fluoride ion selective electrode, and 19F nuclear magnetic resonance. The test results showed near complete mineralization of PFAS in the waste without the formation of intermediate fluorinated by-products. The PFAS mineralization efficiency of the sonolysis treatment at two different power densities for similar initial concentrations were almost identical; the G value at 145 W/L was 9.7*10-3 g/kWh, whereas the G value at 90 W/L was 9.3*10-3 g/kWh. The results of this study highlight the implications for the scalability of the sonolytic process to treat high-concentration PFAS waste.

Implications of intracranial hemorrhage associated with stereo-EEG.

OBJECTIVE: Intracranial hemorrhage (ICH) is a known complication during stereo-electroencephalography (sEEG) however true rates remain unknown. We provide a comprehensive review of ICH during sEEG regardless of clinical symptoms. Secondly, we analyzed sEEG recordings to identify electrographic correlates of ICH. METHODS: This is a retrospective study of patients undergoing sEEG between January 2016 and April 2022 at the Mayo Clinic in Rochester. We reviewed medical records and imaging studies to identify ICH. We analyzed ICH by type, electrode trajectories, timing, sEEG findings and outcomes. RESULTS: There were a total of 201 sEEG implants, of which 23 (11%) cases or 0.9% electrodes implanted had evidence of ICH. The majority of affected patients (82%) were either asymptomatic or had mild clinical neurological manifestations. In 90% of patients who proceeded with surgical treatments, outcomes were favorable. The most common sEEG finding in contacts in proximity of ICH was either focal slowing with interictal discharges or focal electrographic seizures. CONCLUSIONS: ICH associated with sEEG is likely under-reported in literature. We present electroencephalographic correlates of ICH that may aid identification of ICH in the course of performing sEEG monitoring. SIGNIFICANCE: Our data provides clinically relevant information on potential risks and outcomes of ICH. Furthermore, our findings aid identification of ICH during sEEG.

Contributions of reactor geometry and ultrasound frequency on the efficiency of sonochemical reactor.

An intermediate-scale reactor with 10L capacity and two transducers operating at 700 and 950 kHz frequencies was developed to study the scalability of the sonolytic destruction of Per and Polyfluoroalkyl substance (PFAS). The impact of frequency, height of liquid or power density, and transducer position on reactor performance was evaluated with the potassium iodide (KI) oxidation and calorimetric power. The dual frequency mode of operation has a synergistic effect based on the triiodide concentration, and calorimetric power. The triiodide concentration, and calorimetric power were higher in this mode compared to the combination of both frequencies operating individually. The sonochemical efficiency for an intermediate-scale reactor (10L) was similar that obtained from a bench-scale reactor (2L), showing the scalability of the sonolytic technology. The placement of the transducer at the bottom or side wall of the reactor had no significant impact on the sonochemical reactivity. The superposition of the ultrasonic field from the dual transducer mode (side and bottom) did not produce a synergistic effect compared to the single transducer mode (bottom or side). This can be attributed to a disturbance due to the interaction of ultrasonic fields of two frequencies from each transducer. With the encouraging results scaling up is in progress for site implementation.

Coupled high and low-frequency ultrasound remediation of PFAS-contaminated soils.

Solids such as soils and sediments contaminated with per- and polyfluorinated alkyl substances (PFAS) from exposure to impacted media, e.g., landfill leachate or biosolids, direct contaminated discharge, and contaminant transport from atmospheric deposition, have caused significant environmental pollution. Such solids can act as secondary sources of PFAS for groundwater and surface water contamination. There are currently no proven technologies that can degrade PFAS in soil and sediments in a cost-effective, environmentally-friendly, and energy-efficient manner. This study examines the use of coupled high and low-frequency ultrasound in desorbing and degrading PFAS in soil, thereby achieving concurrent treatment and destruction of PFAS in soil. Two common PFAS, namely perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), were used to evaluate treatment performance in soils with both low and high organic matter contents. The test results showed that the ultrasound treatment could significantly reduce PFAS concentrations in artificially contaminated soil; however, no significant degradation was achieved. Ultrasound treatment did improve desorption of PFAS from solid particles, particularly from the highly absorbent organic soil; 68.8 ± 1.8% of PFOA and 45.4 ± 4.1% of PFOS were leached from the soil after ultrasound treatment compared to only 28 ± 0.2% of PFOA and 1 ± 3.1% of PFOSafter desorption in water. This work shows that sonication treatment is an effective technology for the removal of PFAS from solids, however, the presence of solids in the solid-liquid slurry can negatively impact ultrasonic cavitation, inhibiting the sonolytic degradation of desorbed PFAS.

A Review of the Applications, Environmental Release, and Remediation Technologies of Per- and Polyfluoroalkyl Substances.

Per- and polyfluoroalkyl substances (PFAS) are pollutants that have demonstrated a high level of environmental persistence and are very difficult to remediate. As the body of literature on their environmental effects has increased, so has regulatory and research scrutiny. The widespread usage of PFAS in industrial applications and consumer products, complicated by their environmental release, mobility, fate, and transport, have resulted in multiple exposure routes for humans. Furthermore, low screening levels and stringent regulatory standards that vary by state introduce considerable uncertainty and potential costs in the environmental management of PFAS. The recalcitrant nature of PFAS render their removal difficult, but existing and emerging technologies can be leveraged to destroy or sequester PFAS in a variety of environmental matrices. Additionally, new research on PFAS remediation technologies has emerged to address the efficiency, costs, and other shortcomings of existing remediation methods. Further research on the impact of field parameters such as secondary water quality effects, the presence of co-contaminants and emerging PFAS, reaction mechanisms, defluorination yields, and the decomposition products of treatment technologies is needed to fully evaluate these emerging technologies, and industry attention should focus on treatment train approaches to improve efficiency and reduce the cost of treatment.

Reassessing the impact of intraoperative electrocorticography on postoperative outcome of patients undergoing standard temporal lobectomy for MRI-negative temporal lobe epilepsy.

OBJECTIVE: Almost 30% of the patients with suspected temporal lobe epilepsy (TLE) have normal results on MRI. Success rates for resection of MRI-negative TLE are less favorable, ranging from 36% to 76%. Herein the authors describe the impact of intraoperative electrocorticography (ECoG) augmented by opioid activation and its effect on postoperative seizure outcome. METHODS: Adult and pediatric patients with medically resistant MRI-negative TLE who underwent standardized ECoG at the time of their elective anterior temporal lobectomy (ATL) with amygdalohippocampectomy between 1990 and 2016 were included in this study. Seizure recurrence comprised the primary outcome of interest and was assessed using Kaplan-Meier and multivariable Cox regression analysis plots based on distribution of interictal epileptiform discharges (IEDs) recorded on scalp electroencephalography, baseline and opioid-induced IEDs on ECoG, and extent of resection. RESULTS: Of the 1144 ATLs performed at the authors' institution between 1990 and 2016, 127 (11.1%) patients (81 females) with MRI-negative TLE were eligible for this study. Patients with complete resection of tissue generating IED recorded on intraoperative ECoG were less likely to have seizure recurrence compared to those with incomplete resection on univariate analysis (p < 0.05). No difference was found in seizure recurrence between patients with bilateral independent IEDs and unilateral IEDs (p = 0.15), presence or absence of opioid-induced epileptiform activation (p = 0.61), or completeness of resection of tissue with opioid-induced IEDs on intraoperative ECoG (p = 0.41). CONCLUSIONS: The authors found that incomplete resection of IED-generating tissue on intraoperative ECoG was associated with an increased chance of seizure recurrence. However, they found that induction of epileptiform activity with intraoperative opioid activation did not provide useful intraoperative data predictive of improving operative results for temporal lobectomy in MRI-negative epilepsy.

Specific pattern of gadolinium enhancement in spondylotic myelopathy.

OBJECTIVE: To highlight a specific under-recognized radiological feature of spondylotic myelopathy often resulting in misdiagnosis. METHODS: Patients evaluated between January 1, 1996 and December 31, 2012 who met the following criteria were included: (1) spondylotic myelopathy was suspected, (2) gadolinium enhancement was detected, and (3) spinal surgery was performed. RESULTS: Fifty-six patients (70% men) whose median age was 53.5 years (range = 24-80) were included. Spinal cord magnetic resonance imaging (cervical in 52; thoracic in 4) revealed longitudinal spindle-shaped T2-signal hyperintensity (100%) and cord enlargement (79%) accompanied by a characteristic pancakelike transverse band of gadolinium enhancement in 41 (73%), typically immediately caudal to the site of maximal spinal stenosis. Forty (71%) patients were initially diagnosed with neoplastic or inflammatory myelopathies, and decompressive surgery was delayed by a median of 11 months (range = 1-64). Spinal cord biopsy in 6 did not reveal any alternative diagnosis. Ninety-five percent were stable or improved. Gadolinium enhancement persisted in 75% at 12 months, raising concern about the accuracy of the initial diagnosis. Twenty patients required a gait aid (36%) at last follow-up (median = 60 months, range = 10-172). The need for a gait aid preoperatively (p = 0.005), but not delay of surgery, predicted the need for gait aid at final follow-up. INTERPRETATION: Transverse pancakelike gadolinium enhancement associated with and just caudal to the site of maximal stenosis and at the rostrocaudal midpoint of a spindle-shaped T2 hyperintensity suggests that spondylosis is the cause of the myelopathy. Persistent enhancement for months to years following decompressive surgery is common. Recognition is important to prevent inappropriate interventions or delay in consideration of a potentially beneficial decompressive surgery.

Treatment of a thoracic dural-pleural fistula with a vascularized omental flap: a case report.

STUDY DESIGN: Case report. OBJECTIVE: To report an unusual case of pseudomeningocele with dural-pleural fistula formation and spinal cord herniation after anterior thoracic decompression, as well as a unique surgical method for treating this complication. SUMMARY OF BACKGROUND DATA: Thoracic pseudomeningocele with fistula formation is a rare but serious complication of spinal surgery. The negative pressure environment created in the pleural space can complicate management and result in dural-plural fistula formation. We report on the use of a vascularized omental flap to treat this complication after failure of more traditional techniques. METHODS: A 76-year-old man presented with complaints of myeloradiculopathy, including weakness of lower extremities, with gait and bowel and bladder dysfunction after 2 previous decompressions at the T6-T7 level. Revision surgery was complicated by a dural-plural fistula and spinal cord herniation with neurological deterioration requiring reoperation. RESULTS: Treatment with vascularized omental flap successfully treated the fistula, and the patient had resolution of all symptoms with the exception of some lower extremity neuropathic pain. Postoperative imaging showed excellent decompression of the spinal canal and a small, stable pseudomeningocele without evidence of cerebrospinal fluid hypotension or active dural-pleural fistula. CONCLUSION: Treatment of thoracic psuedomeningoceles and fistulas can be difficult due to the unique negative intrathoracic pressure environment that complicates closure using traditional methods. Alternative treatment options may be necessary when more traditional techniques fail. Our report highlights one such option, a vascularized omental flap, which was used to successfully treat the patient.

Multiple-channel scaffolds to promote spinal cord axon regeneration.

As molecular, cellular, and tissue-level treatments for spinal cord injury are discovered, it is likely that combinations of such treatments will be necessary to elicit functional recovery in animal models or patients. We describe multiple-channel, biodegradable scaffolds that serve as the basis for a model to investigate simultaneously the effects on axon regeneration of scaffold architecture, transplanted cells, and locally delivered molecular agents. Poly(lactic-co-glycolic acid) (PLGA) with copolymer ratio 85:15 was used for these initial experiments. Injection molding with rapid solvent evaporation resulted in scaffolds with a plurality of distinct channels running parallel along the length of the scaffolds. The feasibility of creating scaffolds with various channel sizes and geometries was demonstrated. Walls separating open channels were found to possess void fractions as high as 89%, with accessible void fractions as high as 90% through connections 220 microm or larger. Scaffolds degraded in vitro over a period of 30 weeks, over which time-sustained delivery of a surrogate drug was observed for 12 weeks. Primary neonatal Schwann cells were distributed in the channels of the scaffold and remained viable in tissue culture for at least 48 h. Schwann-cell containing scaffolds implanted into transected adult rat spinal cords contained regenerating axons at one month post-operation. Axon regeneration was demonstrated by three-dimensional reconstruction of serial histological sections.

Intrinsic spinal cord catheter placement: implications of new intractable pain in a patient with a spinal cord injury.

We present a case of new intractable flank pain after intrathecal infusion system placement in a 45-yr-old man with a history of a T12 spinal cord injury with dysesthetic leg pain. Pain after intrathecal infusion system placement was evaluated by magnetic resonance imaging and the catheter was found to be intraparenchymal. The patient was treated by cessation of infusion and surgical removal of the system. Before surgical removal, the pump was turned off and the patient's flank pain resolved. Increased vigilance is warranted when caring for paraplegic patients. When new pain persists, intrathecal medication tapering should be considered.