Dynamic Stimulation of Visual Cortex Produces Form Vision in Sighted and Blind Humans.

A visual cortical prosthesis (VCP) has long been proposed as a strategy for restoring useful vision to the blind, under the assumption that visual percepts of small spots of light produced with electrical stimulation of visual cortex (phosphenes) will combine into coherent percepts of visual forms, like pixels on a video screen. We tested an alternative strategy in which shapes were traced on the surface of visual cortex by stimulating electrodes in dynamic sequence. In both sighted and blind participants, dynamic stimulation enabled accurate recognition of letter shapes predicted by the brain's spatial map of the visual world. Forms were presented and recognized rapidly by blind participants, up to 86 forms per minute. These findings demonstrate that a brain prosthetic can produce coherent percepts of visual forms.

Perception and Memory Reinstatement Engage Overlapping Face-Selective Regions within Human Ventral Temporal Cortex.

Humans have the remarkable ability to vividly retrieve sensory details of past events. According to the theory of sensory reinstatement, during remembering, brain regions specialized for processing specific sensory stimuli are reactivated to support content-specific retrieval. Recently, several studies have emphasized transformations in the spatial organization of these reinstated activity patterns. Specifically, studies of scene stimuli suggest a clear anterior shift in the location of retrieval activations compared with the activity observed during perception. However, it is not clear that such transformations occur universally, with inconsistent evidence for other important stimulus categories, particularly faces. One challenge in addressing this question is the careful delineation of face-selective cortices, which are interdigitated with other selective regions, in configurations that spatially differ across individuals. Therefore, we conducted a multisession neuroimaging study to first carefully map individual participants' (nine males and seven females) face-selective regions within ventral temporal cortex (VTC), followed by a second session to examine the activity patterns within these regions during face memory encoding and retrieval. While face-selective regions were expectedly engaged during face perception at encoding, memory retrieval engagement exhibited a more selective and constricted reinstatement pattern within these regions, but did not show any consistent direction of spatial transformation (e.g., anteriorization). We also report on unique human intracranial recordings from VTC under the same experimental conditions. These findings highlight the importance of considering the complex configuration of category-selective cortex in elucidating principles shaping the neural transformations that occur from perception to memory.

Biased Orientation and Color Tuning of the Human Visual Gamma Rhythm.

Narrowband γ oscillations (NBG: ∼20-60 Hz) in visual cortex reflect rhythmic fluctuations in population activity generated by underlying circuits tuned for stimulus location, orientation, and color. A variety of theories posit a specific role for NBG in encoding and communicating this information within visual cortex. However, recent findings suggest a more nuanced role for NBG, given its dependence on certain stimulus feature configurations, such as coherent-oriented edges and specific hues. Motivated by these factors, we sought to quantify the independent and joint tuning properties of NBG to oriented and color stimuli using intracranial recordings from the human visual cortex (male and female). NBG was shown to display a cardinal orientation bias (horizontal) and also an end- and mid-spectral color bias (red/blue and green). When jointly probed, the cardinal bias for orientation was attenuated and an end-spectral preference for red and blue predominated. This loss of mid-spectral tuning occurred even for recording sites showing large responses to uniform green stimuli. Our results demonstrate the close, yet complex, link between the population dynamics driving NBG oscillations and known feature selectivity biases for orientation and color within visual cortex. Such a bias in stimulus tuning imposes new constraints on the functional significance of the visual γ rhythm. More generally, these biases in population electrophysiology will need to be considered in experiments using orientation or color features to examine the role of visual cortex in other domains, such as working memory and decision-making.SIGNIFICANCE STATEMENT Oscillations in electrophysiological activity occur in visual cortex in response to stimuli that strongly drive the orientation or color selectivity of visual neurons. The significance of this induced "γ rhythm" to brain function remains unclear. Answering this question requires understanding how and why some stimuli can reliably generate oscillatory γ activity while others do not. We examined how different orientations and colors independently and jointly modulate γ oscillations in the human brain. Our data show that γ oscillations are greatest for certain orientations and colors that reflect known response biases in visual cortex. Such findings complicate the functional significance of γ oscillations but open new avenues for linking circuits to population dynamics in visual cortex.

Optimizing Perioperative Care in Transsphenoidal Pituitary Surgery: Considerations for Enhanced Recovery After Surgery.

OBJECTIVE: To identify key recommendations for maximizing the efficiency and efficacy of perioperative care in transsphenoidal pituitary surgery. METHODS: The authors performed a comprehensive literature search of Enhanced Recovery After Surgery protocols implemented for patients undergoing transsphenoidal adenomectomy (TSA); individual recommendations were abstracted, and the evidence base thoroughly reviewed. RESULTS: The authors identified 19 individual recommendations pertinent to the care of patients undergoing TSA, which were subdivided into preoperative (n=6), intraoperative (n=6), and postoperative (n=7) interventions. Key factors recommended for minimizing length of stay, preventing readmission, and improving patient outcomes included comprehensive patient education, multidisciplinary evaluation, avoidance of routine lumbar drain placement and nasal packing, and rigorous postoperative monitoring of pituitary function and salt-water imbalances. The overall level of evidence for 7/19 (37%) implemented recommendations was found to be low, suggesting a need for continued research in this patient population. CONCLUSION: Several key interventions should be considered in the development of Enhanced Recovery After Surgery protocols for TSA, which may aid in further decreasing length of stay and promoting positive patient outcomes.

Molecular profiling predicts meningioma recurrence and reveals loss of DREAM complex repression in aggressive tumors.

Meningiomas account for one-third of all primary brain tumors. Although typically benign, about 20% of meningiomas are aggressive, and despite the rigor of the current histopathological classification system there remains considerable uncertainty in predicting tumor behavior. Here, we analyzed 160 tumors from all 3 World Health Organization (WHO) grades (I through III) using clinical, gene expression, and sequencing data. Unsupervised clustering analysis identified 3 molecular types (A, B, and C) that reliably predicted recurrence. These groups did not directly correlate with the WHO grading system, which classifies more than half of the tumors in the most aggressive molecular type as benign. Transcriptional and biochemical analyses revealed that aggressive meningiomas involve loss of the repressor function of the DREAM complex, which results in cell-cycle activation; only tumors in this category tend to recur after full resection. These findings should improve our ability to predict recurrence and develop targeted treatments for these clinically challenging tumors.

Responses to Visual Speech in Human Posterior Superior Temporal Gyrus Examined with iEEG Deconvolution.

Experimentalists studying multisensory integration compare neural responses to multisensory stimuli with responses to the component modalities presented in isolation. This procedure is problematic for multisensory speech perception since audiovisual speech and auditory-only speech are easily intelligible but visual-only speech is not. To overcome this confound, we developed intracranial encephalography (iEEG) deconvolution. Individual stimuli always contained both auditory and visual speech, but jittering the onset asynchrony between modalities allowed for the time course of the unisensory responses and the interaction between them to be independently estimated. We applied this procedure to electrodes implanted in human epilepsy patients (both male and female) over the posterior superior temporal gyrus (pSTG), a brain area known to be important for speech perception. iEEG deconvolution revealed sustained positive responses to visual-only speech and larger, phasic responses to auditory-only speech. Confirming results from scalp EEG, responses to audiovisual speech were weaker than responses to auditory-only speech, demonstrating a subadditive multisensory neural computation. Leveraging the spatial resolution of iEEG, we extended these results to show that subadditivity is most pronounced in more posterior aspects of the pSTG. Across electrodes, subadditivity correlated with visual responsiveness, supporting a model in which visual speech enhances the efficiency of auditory speech processing in pSTG. The ability to separate neural processes may make iEEG deconvolution useful for studying a variety of complex cognitive and perceptual tasks.SIGNIFICANCE STATEMENT Understanding speech is one of the most important human abilities. Speech perception uses information from both the auditory and visual modalities. It has been difficult to study neural responses to visual speech because visual-only speech is difficult or impossible to comprehend, unlike auditory-only and audiovisual speech. We used intracranial encephalography deconvolution to overcome this obstacle. We found that visual speech evokes a positive response in the human posterior superior temporal gyrus, enhancing the efficiency of auditory speech processing.

Electrocorticography reveals continuous auditory and visual speech tracking in temporal and occipital cortex.

During natural speech perception, humans must parse temporally continuous auditory and visual speech signals into sequences of words. However, most studies of speech perception present only single words or syllables. We used electrocorticography (subdural electrodes implanted on the brains of epileptic patients) to investigate the neural mechanisms for processing continuous audiovisual speech signals consisting of individual sentences. Using partial correlation analysis, we found that posterior superior temporal gyrus (pSTG) and medial occipital cortex tracked both the auditory and the visual speech envelopes. These same regions, as well as inferior temporal cortex, responded more strongly to a dynamic video of a talking face compared to auditory speech paired with a static face. Occipital cortex and pSTG carry temporal information about both auditory and visual speech dynamics. Visual speech tracking in pSTG may be a mechanism for enhancing perception of degraded auditory speech.

Ambulatory neurosurgery in the COVID-19 era: patient and provider satisfaction with telemedicine.

OBJECTIVE: Telemedicine has rapidly expanded in the recent years as technologies have afforded healthcare practitioners the ability to diagnose and treat patients remotely. Due to the COVID-19 pandemic, nonessential clinical visits were greatly limited, and much of the outpatient neurosurgical practice at the authors' institution was shifted quickly to telehealth. Although there are prior data suggesting that the use of telemedicine is satisfactory in other surgical fields, data in neurosurgery are limited. This study aimed to investigate both patient and provider satisfaction with telemedicine and its strengths and limitations in outpatient neurosurgery visits. METHODS: This quality improvement study was designed to analyze provider and patient satisfaction with telemedicine consultations in an outpatient neurosurgery clinic setting at a tertiary care, large-volume, academic center. The authors designed an 11-question survey for neurosurgical providers and a 13-question survey for patients using both closed 5-point Likert scale responses and multiple choice responses. The questionnaires were administered to patients and providers during the period when the clinic restricted in-person visits. At the conclusion of the study, the overall data were analyzed qualitatively and quantitatively. RESULTS: During the study period, 607 surveys were sent out to patients seen by telehealth at the authors' academic center, and 122 responses were received. For the provider survey, 85 surveys were sent out to providers at the authors' center and other academic centers, and 40 surveys were received. Ninety-two percent of patients agreed or strongly agreed that they were satisfied with that particular telehealth visit. Eighty-eight percent of patients agreed that their telehealth visit was more convenient for them than an in-person visit, but only 36% of patients stated they would like their future visits to be telehealth. Sixty-three percent of providers agreed that telehealth visits were more convenient for them than in-person visits, and 85% of responding providers stated that they wished to incorporate telehealth into their future practice. CONCLUSIONS: Although the authors' transition to telehealth was both rapid and unexpected, most providers and patients reported positive experiences with their telemedicine visits and found telemedicine to be an effective form of ambulatory neurosurgical care. Not all patients preferred telemedicine visits over in-person visits, but the high satisfaction with telemedicine by both providers and patients is promising to the future expansion of telehealth in ambulatory neurosurgery.

A somatic mutation in MEN1 gene detected in periventricular nodular heterotopia tissue obtained from depth electrodes.

Periventricular nodular heterotopia (PNH) is a common structural malformation of cortical development. Mutations in the filamin A gene are frequent in familial cases with X-linked PNH. However, many cases with sporadic PNH remain genetically unexplained. Although medically refractory epilepsy often brings attention to the underlying PNH, patients are often not candidates for surgical resection. This limits access to neuronal tissue harboring causal mutations. We evaluated a patient with PNH and medically refractory focal epilepsy who underwent a presurgical evaluation with stereotactically placed electroencephalographic (SEEG) depth electrodes. Following SEEG explantation, we collected trace tissue adherent to the electrodes and extracted the DNA. Whole-exome sequencing performed in a Clinical Laboratory Improvement Amendments-approved genetic diagnostic laboratory uncovered a de novo heterozygous pathogenic variant in novel candidate PNH gene MEN1 (multiple endocrine neoplasia type 1; c.1546dupC, p.R516PfsX15). The variant was absent in an earlier exome profiling of the venous blood-derived DNA. The MEN1 gene encodes the ubiquitously expressed, nuclear scaffold protein menin, a known tumor suppressor gene with an established role in the regulation of transcription, proliferation, differentiation, and genomic integrity. Our study contributes a novel candidate gene in PNH generation and a novel practical approach that integrates electrophysiological and genetic explorations of epilepsy.

Saturation in Phosphene Size with Increasing Current Levels Delivered to Human Visual Cortex.

Electrically stimulating early visual cortex results in a visual percept known as a phosphene. Although phosphenes can be evoked by a wide range of electrode sizes and current amplitudes, they are invariably described as small. To better understand this observation, we electrically stimulated 93 electrodes implanted in the visual cortex of 13 human subjects who reported phosphene size while stimulation current was varied. Phosphene size increased as the stimulation current was initially raised above threshold, but then rapidly reached saturation. Phosphene size also depended on the location of the stimulated site, with size increasing with distance from the foveal representation. We developed a model relating phosphene size to the amount of activated cortex and its location within the retinotopic map. First, a sigmoidal curve was used to predict the amount of activated cortex at a given current. Second, the amount of active cortex was converted to degrees of visual angle by multiplying by the inverse cortical magnification factor for that retinotopic location. This simple model accurately predicted phosphene size for a broad range of stimulation currents and cortical locations. The unexpected saturation in phosphene sizes suggests that the functional architecture of cerebral cortex may impose fundamental restrictions on the spread of artificially evoked activity and this may be an important consideration in the design of cortical prosthetic devices.SIGNIFICANCE STATEMENT Understanding the neural basis for phosphenes, the visual percepts created by electrical stimulation of visual cortex, is fundamental to the development of a visual cortical prosthetic. Our experiments in human subjects implanted with electrodes over visual cortex show that it is the activity of a large population of cells spread out across several millimeters of tissue that supports the perception of a phosphene. In addition, we describe an important feature of the production of phosphenes by electrical stimulation: phosphene size saturates at a relatively low current level. This finding implies that, with current methods, visual prosthetics will have a limited dynamic range available to control the production of spatial forms and that more advanced stimulation methods may be required.

A Double Dissociation between Anterior and Posterior Superior Temporal Gyrus for Processing Audiovisual Speech Demonstrated by Electrocorticography.

Human speech can be comprehended using only auditory information from the talker's voice. However, comprehension is improved if the talker's face is visible, especially if the auditory information is degraded as occurs in noisy environments or with hearing loss. We explored the neural substrates of audiovisual speech perception using electrocorticography, direct recording of neural activity using electrodes implanted on the cortical surface. We observed a double dissociation in the responses to audiovisual speech with clear and noisy auditory component within the superior temporal gyrus (STG), a region long known to be important for speech perception. Anterior STG showed greater neural activity to audiovisual speech with clear auditory component, whereas posterior STG showed similar or greater neural activity to audiovisual speech in which the speech was replaced with speech-like noise. A distinct border between the two response patterns was observed, demarcated by a landmark corresponding to the posterior margin of Heschl's gyrus. To further investigate the computational roles of both regions, we considered Bayesian models of multisensory integration, which predict that combining the independent sources of information available from different modalities should reduce variability in the neural responses. We tested this prediction by measuring the variability of the neural responses to single audiovisual words. Posterior STG showed smaller variability than anterior STG during presentation of audiovisual speech with noisy auditory component. Taken together, these results suggest that posterior STG but not anterior STG is important for multisensory integration of noisy auditory and visual speech.

Brain-responsive neurostimulation in patients with medically intractable mesial temporal lobe epilepsy.

OBJECTIVE: Evaluate 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. METHODS: Subjects 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. RESULTS: There 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). SIGNIFICANCE: Brain-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.

Brain-responsive neurostimulation in patients with medically intractable seizures arising from eloquent and other neocortical areas.

OBJECTIVE: Evaluate the seizure-reduction response and safety of brain-responsive stimulation in adults with medically intractable partial-onset seizures of neocortical origin. METHODS: Patients 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. RESULTS: There 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. SIGNIFICANCE: Brain-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.

Electrocorticography Reveals Enhanced Visual Cortex Responses to Visual Speech.

Human speech contains both auditory and visual components, processed by their respective sensory cortices. We test a simple model in which task-relevant speech information is enhanced during cortical processing. Visual speech is most important when the auditory component is uninformative. Therefore, the model predicts that visual cortex responses should be enhanced to visual-only (V) speech compared with audiovisual (AV) speech. We recorded neuronal activity as patients perceived auditory-only (A), V, and AV speech. Visual cortex showed strong increases in high-gamma band power and strong decreases in alpha-band power to V and AV speech. Consistent with the model prediction, gamma-band increases and alpha-band decreases were stronger for V speech. The model predicts that the uninformative nature of the auditory component (not simply its absence) is the critical factor, a prediction we tested in a second experiment in which visual speech was paired with auditory white noise. As predicted, visual speech with auditory noise showed enhanced visual cortex responses relative to AV speech. An examination of the anatomical locus of the effects showed that all visual areas, including primary visual cortex, showed enhanced responses. Visual cortex responses to speech are enhanced under circumstances when visual information is most important for comprehension.

Activation of extracellular regulated kinase and mechanistic target of rapamycin pathway in focal cortical dysplasia.

Neuropathology of resected brain tissue has revealed an association of focal cortical dysplasia (FCD) with drug-resistant epilepsy (DRE). Recent studies have shown that the mechanistic target of rapamycin (mTOR) pathway is hyperactivated in FCD as evidenced by increased phosphorylation of the ribosomal protein S6 (S6) at serine 240/244 (S(240/244) ), a downstream target of mTOR. Moreover, extracellular regulated kinase (ERK) has been shown to phosphorylate S6 at serine 235/236 (S(235/236) ) and tuberous sclerosis complex 2 (TSC2) at serine 664 (S(664) ) leading to hyperactive mTOR signaling. We evaluated ERK phosphorylation of S6 and TSC2 in two types of FCD (FCD I and FCD II) as a candidate mechanism contributing to mTOR pathway dysregulation. Tissue samples from patients with tuberous sclerosis (TS) served as a positive control. Immunostaining for phospho-S6 (pS6(240/244) and pS6(235/236) ), phospho-ERK (pERK), and phospho-TSC2 (pTSC2) was performed on resected brain tissue with FCD and TS. We found increased pS6(240/244) and pS6(235/236) staining in FCD I, FCD II and TS compared to normal-appearing tissue, while pERK and pTSC2 staining was increased only in FCD IIb and TS tissue. Our results suggest that both the ERK and mTOR pathways are dysregulated in FCD and TS; however, the signaling alterations are different for FCD I as compared to FCD II and TS.

Visual recovery after surgical decompression of an occipital intraventricular cyst.

: A 62-year-old woman presented with a chronic left homonymous visual field defect because of a right occipital cyst. Serial visual field examination documented stable visual fields for 12 months, after which there was worsening of visual fields associated with enlargement of the cyst. Surgical decompression of the occipital cyst resulted in marked improvement of the visual field defect over 9 months. This case demonstrates that surgical decompression of cystic lesions adjacent to posterior visual pathways can result in recovery of chronic visual field loss.

Hypophysitis Secondary to Small Vessel ANCA Vasculitis Treated With Rituximab.

Background/Objective: Antineutrophil cytoplasmic antibody (ANCA) associated vasculitis is a rare small vessel vasculitis that can cause pituitary hypophysitis. Hypophysitis is difficult to treat, often requiring high doses of glucocorticoids with frequent flaring as glucocorticoids are tapered. We present a case of ANCA vasculitis involving the pituitary gland successfully treated with rituximab. Case Report: Fifty-one-year-old woman developed progressive frontal headaches, congestion, and epistaxis. Sinus computed tomography scan showed pituitary enlargement and chronic mucosal disease. Pituitary magnetic resonance imaging (MRI) confirmed a diffusely enlarged pituitary with a thickened pituitary stalk. Serologic evaluation revealed elevated inflammatory markers, positive perinuclear ANCA (p-ANCA), and an elevated serum anti-proteinase 3 (anti-PR3) antibody. The patient underwent pituitary biopsy, which showed adenohypophysitis with dense lymphoplasmacytic infiltration, some arranged perivascularly, compatible with involvement of the pituitary gland by ANCA vasculitis. The patient began rituximab and reported resolution of daily headaches, congestion, and epistaxis. Pituitary MRI scan 6 months after rituximab showed reduction in pituitary gland size and stalk thickening. Discussion: ANCA vasculitis is a rare etiology of pituitary hypophysitis, which can present a diagnostic and therapeutic challenge. Pituitary involvement of ANCA vasculitis can be identified through p-ANCA or cytoplasmic ANCA (c-ANCA) and biopsy of the involved tissue. Rituximab, a monoclonal antibody against CD20, has been successfully used to treat ANCA vasculitis and in this case, led to clinical improvements and reduction in the size of the pituitary gland. Conclusion: Pituitary biopsy enabled confirmation of ANCA hypophysitis and facilitated treatment with a steroid-sparing agent.

Multi-institutional Analysis of Endoscopic Sellar Surgical Volumes During the COVID-19 Pandemic.

OBJECTIVE: We sought to quantify trends in operative volumes and complications of endoscopic sellar surgery before and after the COVID-19 pandemic onset. STUDY DESIGN: We performed a retrospective analysis. SETTING: TriNetX database analysis. METHODS: All adults undergoing neuroendoscopy for resection of pituitary tumor (Current Procedural Terminology code 62165) with diagnosis of benign/malignant neoplasm of pituitary gland (D35.2/C75.1) or benign/malignant neoplasm of craniopharyngeal duct (D35.3/C75.2) were included using the TriNetX database for 2 years before (pre-COVID group) and 2 years after (post-COVID group) February 17, 2020. RESULTS: A total of 1238 patients in the pre-COVID group and 1186 patients in the post-COVID group were compared. Age, gender, and race were statistically similar between the groups (P > .05). Surgical volume decreased by 6% in the post-COVID group. In 2020 Q2, operative volume decreased by 19%, and in 2021 Q4 (peak COVID-19 caseload in the United States), operative volumes decreased by 29% compared to 2 years prior. Postoperative complications including meningitis (P = .49), cerebrospinal fluid leak (P = .36), visual field deficits (P = .07), postoperative pneumonia or respiratory failure (P = .42), and 30-day readmission rates (P = .89) were similar between the 2 groups. CONCLUSION: Overall, endoscopic sellar surgery may continue to fluctuate with increased COVID-19 outbreaks. Patient outcomes do not appear to be worsened by decreased operative volumes or delays in nonurgent surgeries.

Epidural Interlay Graft for Pituitary Surgery: A 4-Year Institutional Experience.

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.