What is the Accuracy of PEEK Implants for Cranioplasty in Comparison to Their Patient Specific Surgical Plan?

PURPOSE: Patient specific virtual surgical planning is a useful tool in craniofacial reconstruction. The aim of this paper is to quantify the surgical accuracy of polyetheretherketone (PEEK) cranial implant placement by comparing a computer tomography (CT)-based plan with the measured postoperative position. MATERIALS AND METHODS: This is a retrospective case series. All patients who presented for evaluation and management of cranial defects at the University Health Sciences Center at San Antonio from June 2018 to July 2021 were eligible for the study. For each patient, we assessed accuracy by comparing the planned PEEK implant position, defined by a 3-dimensional mesh, to the measured postoperative position at multiple mesh vertices. The primary outcome variable in our study is the root mean square error (RMSE) between the planned position and the actual position of the implant. RESULTS: Twelve patients (7 men, 5 women, mean age: 25.6, median age: 30.5, range 6-74) were identified who underwent cranioplasty procedures with custom-made PEEK implants to reconstruct cranial defects. The RMSE of the vertex positions ranged between 0.66 and 3.1 millimeters (mm). Eleven of the twelve patients had an RMSE less than 2 mm. The Spearman rank-order correlation between the average error and the length and area of the implant were 0.59 (P = .04, significant) and 0.42 (P = .17, nonsignificant), respectively. The Pearson correlation between age and RMSE was -0.18 (P = .57), and not significant. CONCLUSION: Patient specific implant planning can design and guide the implant placement with a typical accuracy within 2 mm. This level of accuracy suggests that we can place implants accurately enough to achieve good patient aesthetics. The quantitative analysis suggests that the key to accurate placement is understanding the number and spatial distribution of plates and fixation.

Supratentorial ependymoma, zinc finger translocation-associated fusion positive, with extensive synaptophysin immunoreactivity arising from malignant transformation of clear cell ependymoma: A case report.

Background: We describe a case of a supratentorial ependymoma, zinc finger translocation-associated (ZFTA) fusion positive with extensive synaptophysin immunoreactivity arising from malignant transformation of an ependymoma with clear cell features in a patient with long-term follow-up. Case Description: A 55-year-old woman presented with seizures and ataxia 15 years after an initial resection of a clear cell ependymoma, Grade 2. Imaging demonstrated an enhancing right paracentral mass and the patient underwent biopsy and resection. Microscopic analysis showed regions of the tumor with morphological and immunohistochemical features typical of ependymoma, including perivascular pseudorosettes and focal dot- like epithelial membrane antigen positivity, as well as high-grade features. In addition, the neoplasm contained large nodular regions of clear cells exhibiting extensive synaptophysin immunoreactivity, suggestive of neural differentiation, and only focally positive immunoreactivity for glial markers. Electron microscopy showed poorly formed and ill-defined junctional complexes, but no cilia, microvilli, or dense granules were seen. Molecular profiling revealed the presence of a fusion between ZFTA (previously known as C11orf95) and RELA fusion. Conclusion: We report a case of extensive synaptophysin immunoreactivity in a ZFTA-RELA fusion-positive ependymoma that had undergone malignant transformation from a clear cell ependymoma and has long-term follow-up, contributing to the assessment of prognostic significance of synaptophysin immunoreactivity in supratentorial ependymoma, ZFTA fusion positive.

Cerebral blood flow differences between high- vs low-frequency VNS therapy in the epileptic baboon.

PURPOSE: Cerebral blood flow (CBF) tracks physiological effects of ictal or interictal epileptic discharges (IEDs) and neurostimulation. This study compared CBF changes between high-frequency (HF; 300 Hz) microburst, and standard, low-frequency (LF; 30 Hz) vagal nerve stimulation (VNS) Therapy in 2 baboons with genetic generalized epilepsy (GGE), including one with photosensitivity. METHODS: The baboons were selected based on video recordings and scalp EEG studies. They were both implanted with Sentiva™ 1000 devices capable of stimulating at standard and microburst frequencies. Nine H215O (10-20 mCi) positron emission tomographic (PET) scans were performed each session (two PET sessions acquired for each animal). The baboons were sedated with ketamine, paralyzed, and monitored with scalp EEG. CBF changes were compared between the two modes of stimulation and resting scans in the first study, while in the second, VNS Therapy trials were combined with intermittent light stimulation (ILS) at 25 Hz and compared to CBF changes induced by ILS alone. RESULTS: ILS-associated IED rates were slightly reduced by HF- and LF-VNS Therapies in B1, while spontaneous IEDs were completely suppressed by HF-VNS Therapy in B2. Regional CBF changes were consistent between the two modes of therapy in each baboon, in particular with respect to the activation of the superior colliculus and cerebellum. Neither VNS mode suppressed the photoepileptic response in B1. In B2, IED suppression was associated with bilateral deactivations of the frontal and temporal cortices, cingulate and anterior striatum, as well as bilateral cerebellar activations. CONCLUSIONS: This pilot study reveals similar activation/deactivation patterns between LF- and HF-VNS Therapies, but the most pronounced CBF differences between the two baboons and the two modes of stimulation may have been driven by the suppression of the epileptic network by HF-VNS Therapy in B2. Some therapeutic targets appear to be subcortical, including the putamen, superior colliculus, brainstem nuclei, as well as the cerebellum, all of which modulate corticothalamic networks, which is particularly reflected by CBF changes associated with HF-VNS Therapy. These findings need to be replicated in larger samples and correlated with long-term clinical outcomes.

Cortical responsive neurostimulation in a baboon with genetic generalized epilepsy.

OBJECTIVE: To evaluate the efficacy of cortical responsive neurostimulation (CRN) in a male baboon with epilepsy and with genetic generalized epilepsy (GGE), as well as the alteration of seizure patterns and their circadian rhythms due to treatment. METHODS: The baboon was implanted with two subdural frontoparietal strips, bridging the medial central sulci bilaterally. Electrocorticography (ECoG) data were downloaded daily during a three-month baseline, then every 2-3 days over a five-month treatment period. Long episodes, reflecting ictal or interictal epileptic discharges, were also quantified. RESULTS: Twenty-three generalized tonic-clonic seizures (GTCS) and 2 episodes of nonconvulsive status epilepticus (NCSE) were recorded at baseline (median 8 events/month), whereas 26 GTCS were recorded under treatment (median 5/month). Similarly, daily indices of long episodes decreased from 0.46 at baseline to 0.29 with treatment. Ictal ECoG patterns and the circadian distribution of GTCS were also altered by RNS therapy. SIGNIFICANCE: This case study provides the proof-of-concept for RNS therapy in the baboon model of GGE. Cortical responsive neurostimulation (CRN) demonstrated a 38% median reduction in GTCS. Distinct ictal patterns were identified, which changed over the treatment period; the circadian pattern of his GTCS also shifted gradually from night to daytime with treatment. Future studies targeting the thalamic nuclei, or combining cortical and subcortical sites, may further improve detection and control of GTCS as well as other generalized seizure types. More broadly, this study demonstrates opportunities for evaluating seizure detection as well as chronic therapeutic interventions over long term in the baboon.

Assessment of burnout prevention and wellness programs for US-based neurosurgical faculty and residents: a systematic review of the literature.

OBJECTIVE: Neurosurgeon burnout is a serious and prevalent issue that has been shown to impact professionalism, physician health, and patient outcomes. Interventions targeting physician burnout primarily focus on improving physician wellness. Many academic neurosurgery programs have established wellness curricula to combat burnout and improve wellness. No official recommendations exist for establishing a wellness program that effectively targets sources of burnout. The aim of this review was to examine measures of burnout and report objective results of wellness interventions for neurosurgical faculty and residents. METHODS: Two systematic literature reviews were performed in parallel, in accordance with PRISMA 2009 guidelines. Following removal of duplicates, a query of PubMed/MEDLINE, Scopus, Ovid, Cochrane, and EMBASE databases yielded 134 resident-related articles and 208 faculty-related articles for abstract screening. After abstract screening, 17 articles with a primary focus of resident wellness and 10 with a focus on faculty wellness met criteria for full-text screening. Of the total 27 screened articles, 9 (6 resident, 2 faculty, 1 both resident and faculty) met criteria and were included in the final analysis. Article quality was assessed using the Joanna Briggs Institute critical appraisal tools for cohort studies. RESULTS: Included studies reported burnout rates for neurosurgery residents of 30%-67%. Work-life imbalance, imbalance of duties, inadequate operative exposure, and hostile faculty were contributors to burnout. The 2 included studies reported burnout rates for neurosurgery faculty members of 27% and 56.7%. Psychosocial stressors, relational stressors, and financial uncertainty were generally associated with increased feelings of burnout. Of the 4 studies reporting on outcomes of wellness initiatives included in this review, 3 reported a positive impact of the wellness interventions and 1 study reported no significant improvement after implementing a wellness initiative. CONCLUSIONS: Burnout among neurosurgical faculty and residents is prevalent and permeates the daily lives of neurosurgeons, negatively affecting patient outcomes, career satisfaction, and quality of life. Many neurosurgery programs have instituted wellness programs to combat burnout, but few have published evidence of improvement after implementation. While studies have shown that residents and faculty recognize the importance of wellness and look favorably on such initiatives, very few studies have reported objective outcomes.

Bilateral amygdala stimulation reduces avoidance behavior in a predator scent posttraumatic stress disorder model.

OBJECTIVE The predator scent model of posttraumatic stress disorder (PTSD) produces prolonged abnormal anxiety and avoidance-like behaviors. Increased basolateral amygdala activity has been shown to correlate with severity of PTSD symptoms in human studies. Modulation of this increased amygdala activity by deep brain stimulation led to improved symptoms in prior studies that used a foot shock model of inducing PTSD. The predator scent model is a different technique that induces long-lasting avoidance behavioral responses by exposing the animal to an inescapable scent of one of its predators. The authors hypothesize that high-frequency stimulation of the bilateral basolateral amygdala will decrease avoidance and anxiety-like behaviors in a predator scent rodent model of PTSD. METHODS Rodents underwent cat urine exposure in a place preference protocol. Avoidance in the place preference paradigm and anxiety-like behavior in the elevated plus maze were measured before and after high-frequency stimulation. RESULTS Predator scent exposure resulted in long-term significant avoidance behavior in rodents. Bilateral stimulation significantly decreased avoidance behavior in rodents compared to no stimulation following predator scent exposure. There were no significant differences in anxiety behaviors on the elevated plus maze between stimulated and unstimulated cohorts. CONCLUSIONS Bilateral stimulation of the basolateral amygdala leads to decreased avoidance behavior compared to controls in a predator scent model of PTSD.

Case of Lumbar Schwannoma Presenting with Isolated Signs and Symptoms of Intracranial Hypertension.

BACKGROUND: Hydrocephalus and intracranial hypertension are rare signs of spinal tumors when presenting in isolation, particularly with benign tumors. CASE DESCRIPTION: Herein reported is a case of a 53-year-old woman who presented with headache, blurry vision, communicating hydrocephalus, and intracranial hypertension. No primary intracranial pathology was identified, and there were no clinical signs or symptoms of intraspinal pathology. Lumbar puncture revealed elevated opening pressure, cerebrospinal fluid protein, and suspected tumor cells in the cerebrospinal fluid, thus prompting spinal imaging. A primary lumbar schwannoma was subsequently determined to underlie her symptoms, which resolved with tumor resection. CONCLUSIONS: Clinical suspicion of spinal pathology should be maintained in patients with unexplained intracranial hypertension, even in the absence of localizing signs of spinal pathology.

A Unique Case for Spinal Cord Stimulation: Successful Treatment of Small Fiber Neuropathy Pain Using Multiple Spinal Cord Stimulators.

Spinal cord stimulators have commonly been used to treat multiple pain conditions. This case report represents a unique case of using multiple spinal cord stimulators for widespread small fiber neuropathy pain. This case report concerns patient JJ who first presented with generalized neuropathic pain. His pain was an intermittent burning, stinging quality that originally focused in both of his feet and progressed to include his legs and arms and eventually involved his entire body. The pain would last moments to hours at least daily. He reported a poor quality of life. He was diagnosed with small fiber neuropathy with anhydrosis, suggestive of idiopathic erythromelalgia. He had a spinal cord stimulator trial involving both cervical and lower thoracic percutaneous leads. After two spinal cord stimulators were implanted, the patient began to report an improvement in pain. The patient continues to report excellent pain relief. The patient uses the stimulator intermittently as needed, in an abortive fashion for pain flares. The patient is very pleased and has increased his activity. He now attends graduate school full time. This case report hopes to illustrate a unique use of multiple spinal cord stimulators in treating widespread neuropathic pain caused by small fiber neuropathy.

Temporopolar bridging veins during anteromedial temporal strip placement: a case report on complication avoidance†.

INTRODUCTION: Surgery for temporal lobe epilepsy is proven to be beneficial in the treatment of medically refractory temporal lobe epilepsy. Subdural electrode strips are commonly passed in a blind fashion, allowing additional EEG coverage without requiring larger exposure. However, this increases risk of complication, specifically through vascular injury. CASE REPORT: We present a case of a 22-year-old male with medically refractory epilepsy. During passage of an anterior medial temporal strip electrode, resistance was encountered despite multiple attempts and redirection. This strip was abandoned. During the subsequent resection operation, a large temporopolar bridging vein complex was noted and photographed precisely where we encountered resistance. CONCLUSION: Although much frequently less encountered than paramedian subdural strips, anterior medial temporal strip subdural electrodes may indeed injure large bridging veins. As subdural strips are passed where bony exposure is minimal, potential disastrous complications may arise if extreme caution is not used.

Functional Hemispherectomy for Refractory Status Epilepticus in 2 Adults.

BACKGROUND: Status epilepticus (SE) is a medical emergency, as deleterious long-term effects are well known. Medically induced burst suppression is often required if first-line and second-line treatments fail. Surgical intervention can be considered in some patients after prolonged treatment failure of medically induced coma. Multiple surgical options for terminating SE have been demonstrated in the literature, with only 2 reports including hemispherectomy in adults. CASE DESCRIPTION: We present 2 cases of adults with refractory SE who failed more conservative medical/surgical treatment but responded to functional hemispherectomy. Pertinent electroencephalography and imaging findings are discussed. In addition, all previously published pediatric and adult cases are briefly reviewed. CONCLUSIONS: Functional hemispherectomy can be considered in patients, including adults, with super-refractory SE and diffuse hemispheric onset. We report acceptable outcomes and quality of life in our 2 patients.

Influence of Intracranial Electrode Density and Spatial Configuration on Interictal Spike Localization: A Case Study.

PURPOSE: Poor seizure outcomes after epilepsy surgery often reflect an incorrect localization of the epileptic sources by standard intracranial EEG interpretation because of limited electrode coverage of the epileptogenic zone. This study investigates whether, in such conditions, source modeling is able to provide more accurate source localization than the standard clinical method that can be used prospectively to improve surgical resection planning. METHODS: Suboptimal epileptogenic zone sampling is simulated by subsets of the electrode configuration used to record intracranial EEG in a patient rendered seizure free after surgery. sLORETA and the clinical method solutions are applied to interictal spikes sampled with these electrode subsets and are compared for colocalization with the resection volume and displacement due to electrode downsampling. RESULTS: sLORETA provides often congruent and at times more accurate source localization when compared with the standard clinical method. However, with electrode downsampling, individual sLORETA solution locations can vary considerably and shift consistently toward the remaining electrodes. CONCLUSIONS: sLORETA application can improve source localization based on the clinical method but does not reliably compensate for suboptimal electrode placement. Incorporating sLORETA solutions based on intracranial EEG in surgical planning should proceed cautiously in cases where electrode repositioning is planned on clinical grounds.

Robust selectivity to two-object images in human visual cortex.

We can recognize objects in complex images in a fraction of a second. Neuronal responses in macaque areas V4 and inferior temporal cortex to preferred stimuli are typically suppressed by the addition of other objects within the receptive field (see, however, [16, 17]). How can this suppression be reconciled with rapid visual recognition in complex scenes? Certain "special categories" could be unaffected by other objects, but this leaves the problem unsolved for other categories. Another possibility is that serial attentional shifts help ameliorate the problem of distractor objects. Yet, psychophysical studies, scalp recordings, and neurophysiological recordings suggest that the initial sweep of visual processing contains a significant amount of information. We recorded intracranial field potentials in human visual cortex during presentation of flashes of two-object images. Visual selectivity from temporal cortex during the initial approximately 200 ms was largely robust to the presence of other objects. We could train linear decoders on the responses to isolated objects and decode information in two-object images. These observations are compatible with parallel, hierarchical, and feed-forward theories of rapid visual recognition and may provide a neural substrate to begin to unravel rapid recognition in natural scenes.

Chiari I malformation as a cause of trigeminal neuralgia: case report.

OBJECTIVE: Trigeminal neuralgia (TN) is usually associated with vascular compression of the trigeminal nerve, but some cases are associated with central lesions such as tumors, aneurysms, or arteriovenous malformations. In this article, we report the 19th case of TN associated with Chiari I malformation and review clinical outcomes and pathophysiology. CLINICAL PRESENTATION: A 63-year-old right-handed man initially presented in 1993 with left-sided lancinating facial pain in the V2 distribution of the trigeminal nerve; the pain was triggered by certain movements, tactile stimulation, or a hot shower. Magnetic resonance imaging revealed a Chiari I malformation associated with a syrinx from C1 to C3. INTERVENTION: The patient underwent uncomplicated suboccipital craniectomy, C1 laminectomy, and duraplasty for Chiari decompression. Postoperatively, his pain resolved over a period of 1 year. CONCLUSION: Chiari I malformation has been found to be associated with TN in 19 cases in the English-language literature. In patients refractory to medical treatment, suboccipital decompression leads to resolution of pain in about two-thirds of patients. Potential mechanisms for the pathogenesis of TN in the setting of Chiari I malformation are discussed. Chiari I malformation is important to consider as a rare cause of TN that responds to surgical therapy.

High-resolution three-dimensional microelectrode brain mapping using stereo microfocal X-ray imaging.

Much of our knowledge of brain function has been gleaned from studies using microelectrodes to characterize the response properties of individual neurons in vivo. However, because it is difficult to accurately determine the location of a microelectrode tip within the brain, it is impossible to systematically map the fine three-dimensional spatial organization of many brain areas, especially in deep structures. Here, we present a practical method based on digital stereo microfocal X-ray imaging that makes it possible to estimate the three-dimensional position of each and every microelectrode recording site in "real time" during experimental sessions. We determined the system's ex vivo localization accuracy to be better than 50 microm, and we show how we have used this method to coregister hundreds of deep-brain microelectrode recordings in monkeys to a common frame of reference with median error of <150 microm. We further show how we can coregister those sites with magnetic resonance images (MRIs), allowing for comparison with anatomy, and laying the groundwork for more detailed electrophysiology/functional MRI comparison. Minimally, this method allows one to marry the single-cell specificity of microelectrode recording with the spatial mapping abilities of imaging techniques; furthermore, it has the potential of yielding fundamentally new kinds of high-resolution maps of brain function.

Multiple pilocytic astrocytomas of the cerebellum in a 17-year-old patient with neurofibromatosis type I.

OBJECTIVE: Approximately 10% of patients with neurofibromatosis I (NFI) patients will have central nervous system (CNS) tumors. The most common of these are hypothalamic-optic gliomas, followed by brainstem and cerebellar pilocytic astrocytomas. While isolated pilocytic astrocytomas in NFI are well described, the appearance of multiple pilocytic astrocytomas in an individual patient is less common. The most frequent combination in NFI patients with more than one pilocytic astrocytoma is optic tract/hypothalamic and brainstem. Other combinations are exceedingly rare; multiple pilocytic astrocytomas have only been reported once in the cerebral hemispheres in a patient with NFI. This report presents the first documented case, to our knowledge, of multiple pilocytic astrocytomas in the cerebellum of a patient with NF1. METHODS: Case report. CONCLUSION: The finding of multiple cerebellar pilocytic astrocytomas in a patient with NF1 is important because it expands the spectrum of presentations for patients with NF1 and also highlights specific diagnostic and therapeutic challenges faced by the treating physicians. The genetic and molecular basis of NF1 is reviewed. Strategies of diagnosis and treatment outlined here are relevant to both patients with NF1 and all patients with multiple posterior fossa tumors.

The diagnostic utility of brain biopsy procedures in patients with rapidly deteriorating neurological conditions or dementia.

OBJECT: Obtaining brain biopsy specimens is often the diagnostic test of last resort for patients with unexplained neurological conditions, particularly those with a rapidly deteriorating neurological course. The goals of this analysis were to determine the diagnostic sensitivity of brain biopsy specimens in these types of patients and retrospectively identify features of these disorders that may have enabled an earlier diagnosis, which may prevent the need for diagnostic brain biopsy procedures in the future. METHODS: The authors reviewed the case records of all brain biopsy procedures that had been performed at a single tertiary care institution between January 1993 and April 2002 in 171 patients. Patients with HIV or nonlymphomatous brain tumors were excluded from this analysis because the utility of brain biopsy specimens for these conditions has been determined front previous studies. A subgroup analysis of this cohort was performed in the 64 patients who had comprehensive medical records and a clinical syndrome involving a progressively deteriorating neurological condition of less than 1 year in duration. The overall sensitivity of brain biopsy procedures for diagnostic purposes in the cohort was 65% (111 of 171 patients). The two most common diagnoses in the subgroup with rapidly deteriorating neurological conditions were primary central nervous system (CNS) B-cell lymphoma in 20.3% (13 patients) and Creutzfeldt-Jakob disease in 15.6% (10 patients), followed by viral encephalitis in 14.1% (nine patients) and CNS vasculitis in 9.4% (six patients). Clinical symptoms and laboratory data were compared among the diagnostic groups. CONCLUSIONS: These results will help guide the evaluation of patients with neurological conditions that are difficult to diagnose and will provide a foundation for further prospective studies.