Yoshor, Daniel

Abstract Brain responses to sensory stimuli depend on the specific task performed by the observer. Previously, fMRI measurements in ventral temporal cortex (VTC) showed that BOLD responses to visual input scale with task demands. This scaling of BOLD responses is thought to be driven by the engagement of cognitive functions required for the task. To better understand how these cognitive task demands influence neural activity in VTC, we measured electrocorticography (ECoG) responses to images of varying contrast in two human participants during either a fixation or image categorization task. ECoG high frequency broadband activity (>70 Hz) showed that local neuronal responses increased with image contrast as expected for sensory encoding, and were scaled by task demands approximately 200 ms after stimulus onset. In contrast, ECoG low frequency activity in the alpha/beta range (8-28 Hz) was insensitive to image contrast and showed larger decreases with increasing task demands. These results indicate that high frequencies in VTC reflect both the encoding of sensory inputs and task demands, similar to prior BOLD response measurements, whereas low frequency oscillations represent task demands, not sensory inputs per se. In line with the interpretation that low frequency oscillations reflect pulsed inhibition, we speculate that a power decrease in low frequency oscillations amplifies neural activity in VTC in support of visual task demands.

Abstract Objective Pituitary apoplexy (PA) is a rare condition caused by hemorrhage or infarction of the pituitary gland with associated risk of cranial neuropathies, endocrinopathies, and even death. Human immunodeficiency virus (HIV) has been shown to have some association with pituitary apoplexy, however, large‐scale studies have not been performed. Methods A retrospective cohort study of subjects greater than 18 years of age was performed using the national TriNetX database. The general population was first compared with those undergoing treatment for PA to compare general demographics and incidence of HIV. The PA cohort was then substratified by HIV status and propensity matched by age and sex to evaluate differences in visual outcomes and endocrine metrics. Using the diagnosis of pituitary apoplexy as an index event, the rate of HIV diagnosis at the time of presentation or in the three months following treatment was calculated. Two‐tailed, unpaired t ‐tests were performed. Results A total 2066 patients were identified (902 HIV, 1158 controls). Those with HIV showed an increased rate of pituitary apoplexy (odds ratio [OR]: 19.8) versus healthy adults and were more likely to be younger and male. Among patients treated for pituitary apoplexy, patients with HIV were more likely to have increased thyroid stimulating hormone, reduced T 4 , and increased prolactin compared with healthy controls. There were no significant differences in visual outcomes between HIV positive and control patients. Importantly, 74% of patients did not carry a diagnosis of HIV on presentation but were diagnosed at the time of or in the three months following treatment for pituitary apoplexy. Conclusions Diagnosis and treatment of pituitary apoplexy shows a high rate of concurrent or subsequent diagnosis of HIV. Screening for HIV should be considered in patients undergoing treatment for pituitary apoplexy.

Abstract Objective Sellar repair techniques with varying complexity and effectiveness have been employed to reduce the incidence of postoperative cerebrospinal fluid (CSF) leaks following endoscopic transsphenoidal pituitary surgery. This study describes our institutional experience with a minimalistic, highly effective approach to sellar repair. Methods The authors performed a retrospective review of consecutive cases of transsphenoidal pituitary surgery performed at our institution. All included subjects underwent sellar repair with an epidural interlay graft. Relationships between patient and tumor characteristics, incidence of CSF leak, adjunct repair techniques, and endocrine outcomes were examined. Results Three hundred and thirty-four (334) cases were included. Intraoperative CSF leak was encountered in 116 cases (34.7%), and postoperative CSF leak occurred only once (0.3%) early in the series. Seventy intraoperative CSF leaks were successfully repaired with an epidural interlay alone, including 13 high-flow leaks. Our rate of fat graft use (1.2%), nasoseptal flap (3.0%), and lumbar drain placement (6.6%) in the second half of the series showed a significant decline compared with the first half, indicating increased reliance on the interlay graft over time. Our 65% functional macroadenoma remission rate compares favorably with large historical series. Conclusion Simple sellar repair using an epidural interlay graft is highly effective in preventing postoperative CSF leaks, including cases of high-flow intraoperative leaks. More complex repair techniques are reserved for select high-risk cases or those with inadequate sellar bony ledges. With this technique, there has been no postoperative CSF leak at our institution in over 300 consecutive transsphenoidal pituitary surgeries.

SummaryObjectiveEvaluate the seizure‐reduction response and safety of mesial temporal lobe (MTL) brain‐responsive stimulation in adults with medically intractable partial‐onset seizures of mesial temporal lobe origin.MethodsSubjects with mesial temporal lobe epilepsy (MTLE) were identified from prospective clinical trials of a brain‐responsive neurostimulator (RNS System, NeuroPace). The seizure reduction over years 2–6 postimplantation was calculated by assessing the seizure frequency compared to a preimplantation baseline. Safety was assessed based on reported adverse events.ResultsThere were 111 subjects with MTLE; 72% of subjects had bilateral MTL onsets and 28% had unilateral onsets. Subjects had one to four leads placed; only two leads could be connected to the device. Seventy‐six subjects had depth leads only, 29 had both depth and strip leads, and 6 had only strip leads. The mean follow‐up was 6.1 ± (standard deviation) 2.2 years. The median percent seizure reduction was 70% (last observation carried forward). Twenty‐nine percent of subjects experienced at least one seizure‐free period of 6 months or longer, and 15% experienced at least one seizure‐free period of 1 year or longer. There was no difference in seizure reduction in subjects with and without mesial temporal sclerosis (MTS), bilateral MTL onsets, prior resection, prior intracranial monitoring, and prior vagus nerve stimulation. In addition, seizure reduction was not dependent on the location of depth leads relative to the hippocampus. The most frequent serious device‐related adverse event was soft tissue implant‐site infection (overall rate, including events categorized as device‐related, uncertain, or not device‐related: 0.03 per implant year, which is not greater than with other neurostimulation devices).SignificanceBrain‐responsive stimulation represents a safe and effective treatment option for patients with medically intractable epilepsy, including patients with unilateral or bilateral MTLE who are not candidates for temporal lobectomy or who have failed a prior MTL resection.

SummaryObjectiveEvaluate the seizure‐reduction response and safety of brain‐responsive stimulation in adults with medically intractable partial‐onset seizures of neocortical origin.MethodsPatients with partial seizures of neocortical origin were identified from prospective clinical trials of a brain‐responsive neurostimulator (RNS System, NeuroPace). The seizure reduction over years 2–6 postimplantation was calculated by assessing the seizure frequency compared to a preimplantation baseline. Safety was assessed based on reported adverse events. Additional analyses considered safety and seizure reduction according to lobe and functional area (e.g., eloquent cortex) of seizure onset.ResultsThere were 126 patients with seizures of neocortical onset. The average follow‐up was 6.1 implant years. The median percent seizure reduction was 70% in patients with frontal and parietal seizure onsets, 58% in those with temporal neocortical onsets, and 51% in those with multilobar onsets (last observation carried forward [LOCF] analysis). Twenty‐six percent of patients experienced at least one seizure‐free period of 6 months or longer and 14% experienced at least one seizure‐free period of 1 year or longer. Patients with lesions on magnetic resonance imaging (MRI; 77% reduction, LOCF) and those with normal MRI findings (45% reduction, LOCF) benefitted, although the treatment response was more robust in patients with an MRI lesion (p = 0.02, generalized estimating equation [GEE]). There were no differences in the seizure reduction in patients with and without prior epilepsy surgery or vagus nerve stimulation. Stimulation parameters used for treatment did not cause acute or chronic neurologic deficits, even in eloquent cortical areas. The rates of infection (0.017 per patient implant year) and perioperative hemorrhage (0.8%) were not greater than with other neurostimulation devices.SignificanceBrain‐responsive stimulation represents a safe and effective treatment option for patients with medically intractable epilepsy, including adults with seizures of neocortical onset, and those with onsets from eloquent cortex.