Continuous Intrathecal Medication Delivery With the IRRA flow Catheter: Pearls and Early Experience.

BACKGROUND AND OBJECTIVES: Intrathecal (IT) medications are routinely introduced through catheterization of the intraventricular space or subarachnoid space. There has been sporadic use of IT medications delivered directly to the ventricle either by intermittent injection through an external ventricular drain (EVD) or by an Ommaya reservoir with a ventricular catheter. IT medication delivery through EVD has many drawbacks, including the necessary opening of a sterile system, delivery of medication in a bolus form, and requirements to clamp the EVD after medication delivery. Despite these setbacks, IT medications delivered through EVD have been used across a wide range of applications, including antibiotic delivery treatment of vasospasm with nicardipine and delivery of tissue plasminogen activator. METHODS: We used a newly developed active fluid exchange device to treat various severe conditions involved in the cerebral ventricles. Here, we present our treatment protocols and advice on the techniques related to successful active fluid exchange therapy. RESULTS: Seventy patients have been treated with our system with various conditions, including subarachnoid hemorrhage, intraventricular hemorrhage, ventriculitis, and cerebral abscess. Total complication rate was 14% with only 1 catheter occlusion and low rates of hemorrhage, infection, and spinal fluid leak. CONCLUSION: Current continuous IT medication dosages and protocols are based on reports and consensus statements evaluating intermittent instillation of medication boluses. The pharmacokinetics of continuous dosing and the therapeutic and safety profiles of the medications need to be studied in a prospective manner to evaluate the true optimal dosing standards. Furthermore, the ability to deliver continuous, sterile medications directly through an IT route will open new avenues of pharmacotherapy that were previously closed. This report serves as a basic guide for the safe and effective use of the IRRA flow active fluid exchange catheter to deliver IT medications.

Neural mechanisms of face familiarity and learning in the human amygdala and hippocampus.

Recognizing familiar faces and learning new faces play an important role in social cognition. However, the underlying neural computational mechanisms remain unclear. Here, we record from single neurons in the human amygdala and hippocampus and find a greater neuronal representational distance between pairs of familiar faces than unfamiliar faces, suggesting that neural representations for familiar faces are more distinct. Representational distance increases with exposures to the same identity, suggesting that neural face representations are sharpened with learning and familiarization. Furthermore, representational distance is positively correlated with visual dissimilarity between faces, and exposure to visually similar faces increases representational distance, thus sharpening neural representations. Finally, we construct a computational model that demonstrates an increase in the representational distance of artificial units with training. Together, our results suggest that the neuronal population geometry, quantified by the representational distance, encodes face familiarity, similarity, and learning, forming the basis of face recognition and memory.

Traumatic brain injury in college students and the influence of alcohol consumption: A retrospective review from a rural state.

Objectives: There is a strong association between alcohol consumption and traumatic brain injury (TBI). Students are known to consume alcohol at a high rate. Despite the connection between alcohol and TBI, this is one of few studies to examine the connection between students, alcohol, and TBI. The objective of this study was to explore the relationship between students, alcohol, and TBI. Materials and Methods: A retrospective chart review utilizing the institutional trauma data back was performed for patients 18-26 years of age, admitted to the emergency department with a diagnosis of a TBI and positive blood alcohol. Patient diagnosis, injury mechanism, alcohol level on admission, urine drug screen, mortality, injury severity score, and discharge disposition were recorded. The data were analyzed using Wilcoxon rank-sum tests and Chi-square tests to identify differences between students and non-student groups. Results: Six hundred and thirty-six charts were reviewed for patients aged 18-26 with a positive blood alcohol level and TBI. The sample included 186 students, 209 non-students, and 241 uncertain of status. The student group had significantly higher levels of alcohol than the non-student group (P < 0.0001). P < 0.0001 showed that overall alcohol levels for males are significantly higher than levels of alcohol for females in the student group. Conclusion: Alcohol consumption contributes to significant injuries such as TBI in college students. Male students had a higher prevalence of TBI, and higher alcohol levels than female students. These results can be used to inform and better target harm reduction and alcohol awareness programs.

Single neurons in the human medial temporal lobe flexibly shift representations across spatial and memory tasks.

Investigations into how individual neurons encode behavioral variables of interest have revealed specific representations in single neurons, such as place and object cells, as well as a wide range of cells with conjunctive encodings or mixed selectivity. However, as most experiments examine neural activity within individual tasks, it is currently unclear if and how neural representations change across different task contexts. Within this discussion, the medial temporal lobe is particularly salient, as it is known to be important for multiple behaviors including spatial navigation and memory, however the relationship between these functions is currently unclear. Here, to investigate how representations in single neurons vary across different task contexts in the medial temporal lobe, we collected and analyzed single-neuron activity from human participants as they completed a paired-task session consisting of a passive-viewing visual working memory and a spatial navigation and memory task. Five patients contributed 22 paired-task sessions, which were spike sorted together to allow for the same putative single neurons to be compared between the different tasks. Within each task, we replicated concept-related activations in the working memory task, as well as target-location and serial-position responsive cells in the navigation task. When comparing neuronal activity between tasks, we first established that a significant number of neurons maintained the same kind of representation, responding to stimuli presentations across tasks. Further, we found cells that changed the nature of their representation across tasks, including a significant number of cells that were stimulus responsive in the working memory task that responded to serial position in the spatial task. Overall, our results support a flexible encoding of multiple, distinct aspects of different tasks by single neurons in the human medial temporal lobe, whereby some individual neurons change the nature of their feature coding between task contexts.

Single neurons in the human medial temporal lobe flexibly shift representations across spatial and memory tasks.

Investigations into how individual neurons encode behavioral variables of interest have revealed specific representations in single neurons, such as place and object cells, as well as a wide range of cells with conjunctive encodings or mixed selectivity. However, as most experiments examine neural activity within individual tasks, it is currently unclear if and how neural representations change across different task contexts. Within this discussion, the medial temporal lobe is particularly salient, as it is known to be important for multiple behaviors including spatial navigation and memory, however the relationship between these functions is currently unclear. Here, to investigate how representations in single neurons vary across different task contexts in the MTL, we collected and analyzed single-neuron activity from human participants as they completed a paired-task session consisting of a passive-viewing visual working memory and a spatial navigation and memory task. Five patients contributed 22 paired-task sessions, which were spike sorted together to allow for the same putative single neurons to be compared between the different tasks. Within each task, we replicated concept-related activations in the working memory task, as well as target-location and serial-position responsive cells in the navigation task. When comparing neuronal activity between tasks, we first established that a significant number of neurons maintained the same kind of representation, responding to stimuli presentations across tasks. Further, we found cells that changed the nature of their representation across tasks, including a significant number of cells that were stimulus responsive in the working memory task that responded to serial position in the spatial task. Overall, our results support a flexible encoding of multiple, distinct aspects of different tasks by single neurons in the human MTL, whereby some individual neurons change the nature of their feature coding between task contexts.

Magnetic resonance imaging-guided stereotactic laser ablation therapy for the treatment of pediatric epilepsy: a retrospective multiinstitutional study.

OBJECTIVE: The authors of this study evaluated the safety and efficacy of stereotactic laser ablation (SLA) for the treatment of drug-resistant epilepsy (DRE) in children. METHODS: Seventeen North American centers were enrolled in the study. Data for pediatric patients with DRE who had been treated with SLA between 2008 and 2018 were retrospectively reviewed. RESULTS: A total of 225 patients, mean age 12.8 ± 5.8 years, were identified. Target-of-interest (TOI) locations included extratemporal (44.4%), temporal neocortical (8.4%), mesiotemporal (23.1%), hypothalamic (14.2%), and callosal (9.8%). Visualase and NeuroBlate SLA systems were used in 199 and 26 cases, respectively. Procedure goals included ablation (149 cases), disconnection (63), or both (13). The mean follow-up was 27 ± 20.4 months. Improvement in targeted seizure type (TST) was seen in 179 (84.0%) patients. Engel classification was reported for 167 (74.2%) patients; excluding the palliative cases, 74 (49.7%), 35 (23.5%), 10 (6.7%), and 30 (20.1%) patients had Engel class I, II, III, and IV outcomes, respectively. For patients with a follow-up ≥ 12 months, 25 (51.0%), 18 (36.7%), 3 (6.1%), and 3 (6.1%) had Engel class I, II, III, and IV outcomes, respectively. Patients with a history of pre-SLA surgery related to the TOI, a pathology of malformation of cortical development, and 2+ trajectories per TOI were more likely to experience no improvement in seizure frequency and/or to have an unfavorable outcome. A greater number of smaller thermal lesions was associated with greater improvement in TST. Thirty (13.3%) patients experienced 51 short-term complications including malpositioned catheter (3 cases), intracranial hemorrhage (2), transient neurological deficit (19), permanent neurological deficit (3), symptomatic perilesional edema (6), hydrocephalus (1), CSF leakage (1), wound infection (2), unplanned ICU stay (5), and unplanned 30-day readmission (9). The relative incidence of complications was higher in the hypothalamic target location. Target volume, number of laser trajectories, number or size of thermal lesions, or use of perioperative steroids did not have a significant effect on short-term complications. CONCLUSIONS: SLA appears to be an effective and well-tolerated treatment option for children with DRE. Large-volume prospective studies are needed to better understand the indications for treatment and demonstrate the long-term efficacy of SLA in this population.

Outpatient Deep Brain Stimulation Surgery Is a Safe Alternative to Inpatient Admission.

BACKGROUND: Deep brain stimulation (DBS) is usually performed as an inpatient procedure. The COVID-19 pandemic effected a practice change at our institution with outpatient DBS performed because of limited inpatient and surgical resources. Although this alleviated use of hospital resources, the comparative safety of outpatient DBS surgery is unclear. OBJECTIVE: To compare the safety and incidence of early postoperative complications in patients undergoing DBS procedures in the outpatient vs inpatient setting. METHODS: We retrospectively reviewed all outpatient and inpatient DBS procedures performed by a single surgeon between January 2018 and November 2022. The main outcome measures used for comparison between the 2 groups were total complications, length of stay, rate of postoperative infection, postoperative hemorrhage rate, 30-day emergency department (ED) visits and readmissions, and IV antihypertensive requirement. RESULTS: A total of 44 outpatient DBS surgeries were compared with 70 inpatient DBS surgeries. The outpatient DBS cohort had a shorter mean postoperative stay (4.19 vs 39.59 hours, P = .0015), lower total complication rate (2.3% vs 12.8%, P = .1457), and lower wound infection rate (0% vs 2.9%, P = .52) compared with the inpatient cohort, but the difference in complications was not statistically significant. In the 30-day follow-up period, ED visits were similar between the cohorts (6.8% vs 7.1%, P = .735), but no outpatient DBS patient required readmission, whereas all inpatient DBS patients visiting the ED were readmitted ( P = .155). CONCLUSION: Our study demonstrates that DBS can be safely performed on an outpatient basis with same-day hospital discharge and close continuous monitoring.

A human single-neuron dataset for face perception.

The human amygdala and hippocampus have long been associated with face perception. Here, we present a dataset of single-neuron activity in the human amygdala and hippocampus during face perception. We recorded 2082 neurons from the human amygdala and hippocampus when neurosurgical patients with intractable epilepsy performed a one-back task using natural face stimuli, which mimics natural face perception. Specifically, our data include (1) single-neuron activity from the amygdala (996 neurons) and hippocampus (1086 neurons), (2) eye movements (gaze position and pupil), (3) psychological assessment of the patients, and (4) social trait judgment ratings from a subset of patients and a large sample of participants from the general population. Together, our comprehensive dataset with a large population of neurons can facilitate multifaceted investigation of face perception with the highest spatial and temporal resolution currently available in humans.

A neuronal social trait space for first impressions in the human amygdala and hippocampus.

People instantaneously evaluate faces with significant agreement on evaluations of social traits. However, the neural basis for such rapid spontaneous face evaluation remains largely unknown. Here, we recorded from 490 neurons in the human amygdala and hippocampus and found that the neuronal activity was associated with the geometry of a social trait space. We further investigated the temporal evolution and modulation on the social trait representation, and we employed encoding and decoding models to reveal the critical social traits for the trait space. We also recorded from another 938 neurons and replicated our findings using different social traits. Together, our results suggest that there exists a neuronal population code for a comprehensive social trait space in the human amygdala and hippocampus that underlies spontaneous first impressions. Changes in such neuronal social trait space may have implications for the abnormal processing of social information observed in some neurological and psychiatric disorders.

Face identity coding in the deep neural network and primate brain.

A central challenge in face perception research is to understand how neurons encode face identities. This challenge has not been met largely due to the lack of simultaneous access to the entire face processing neural network and the lack of a comprehensive multifaceted model capable of characterizing a large number of facial features. Here, we addressed this challenge by conducting in silico experiments using a pre-trained face recognition deep neural network (DNN) with a diverse array of stimuli. We identified a subset of DNN units selective to face identities, and these identity-selective units demonstrated generalized discriminability to novel faces. Visualization and manipulation of the network revealed the importance of identity-selective units in face recognition. Importantly, using our monkey and human single-neuron recordings, we directly compared the response of artificial units with real primate neurons to the same stimuli and found that artificial units shared a similar representation of facial features as primate neurons. We also observed a region-based feature coding mechanism in DNN units as in human neurons. Together, by directly linking between artificial and primate neural systems, our results shed light on how the primate brain performs face recognition tasks.

Awake Deep Brain Stimulation Surgery Without Intraoperative Imaging Is Accurate and Effective: A Case Series.

BACKGROUND: The success of deep brain stimulation (DBS) surgery depends on the accuracy of electrode placement. Several factors can affect this such as brain shift, the quality of preoperative planning, and technical factors. It is crucial to determine whether techniques yield accurate lead placement and effective symptom relief. Many of the studies establishing the accuracy of frameless techniques used intraoperative imaging to further refine lead placement. OBJECTIVE: To determine whether awake lead placement without intraoperative imaging can achieve similar minimal targeting error while preserving clinical results. METHODS: Eighty-two trajectories in 47 patients who underwent awake, frameless DBS lead placement with the Fred Haer Corporation STarFix system for essential tremor or Parkinson's disease were analyzed. Neurological testing during lead placement was used to determine appropriate lead locations, and no intraoperative imaging was performed. Accuracy data were compared with previously performed studies. RESULTS: The Euclidean error for the patient cohort was 1.79 ± 1.02 mm, and the Pythagorean error was 1.40 ± 0.95 mm. The percentage symptom improvement evaluated by the Unified Parkinson's Disease Rating Scale for Parkinson's disease or the Fahn-Tolosa-Marin scale for essential tremor was similar to reported values at 58% ± 17.2% and 67.4% ± 24.7%, respectively. The operative time was 95.0 ± 30.3 minutes for all study patients. CONCLUSION: Awake, frameless DBS surgery with the Fred Haer Corporation STarFix system does not require intraoperative imaging for stereotactic accuracy or clinical effectiveness.

Complications of Spine Surgery in "Super Obese" Patients.

STUDY DESIGN: Retrospective chart review with matched control. OBJECTIVE: To evaluate the indications and complications of spine surgery on super obese patients. METHODS: A retrospective review assessed super obese patients undergoing spine surgery at a level-1 trauma and spine referral center from 2012 to 2016. Outcomes were compared to age-matched controls with body mass index (BMI) <50 kg/m2. The control group was further subdivided into patients with BMI <30 kg/m2 (normal) and BMI between 30 and 50 kg/m2 (obese). RESULTS: Sixty-three super obese patients undergoing 86 surgeries were identified. Sixty patients (78 surgeries) were in the control group. Age and number of elective versus nonelective cases were not significantly different. Mean BMI of the super obese group was 55 kg/m2 (range 50-77 kg/m2) versus 29 kg/m2 in the controls (range 20-49 kg/m2). Fifty-two percent of surgeries were elective, and the most common indication was degenerative disease (39%). Compared with controls, super obese patients had a higher complication rate (30% [n = 19] vs 10% [N = 6], P = .0055) but similar 30-day mortality rate (5% vs 5%), a finding that was upheld when comparing super obese with each of the control group stratifications (BMI 30-50 and BMI <30 kg/m2). The most common complication among super obese patients was wound dehiscence/infection (n = 8, 13%); 2 patients' surgeries were aborted. Complication rates for elective surgery were 21% (n = 7) for super obese patients and 4% (n = 1) for controls (P = .121); complication rates for nonelective procedures were 40% (n = 12) and 14% (n = 5), respectively (P = .023). CONCLUSION: The complication rate of spine surgery in super obese patients (BMI ≥ 50 kg/m2) is significantly higher than other patients, particularly for nonelective cases.

Task Modulation of Single-Neuron Activity in the Human Amygdala and Hippocampus.

The human amygdala and hippocampus are critically involved in various processes in face perception. However, it remains unclear how task demands or evaluative contexts modulate processes underlying face perception. In this study, we employed two task instructions when participants viewed the same faces and recorded single-neuron activity from the human amygdala and hippocampus. We comprehensively analyzed task modulation for three key aspects of face processing and we found that neurons in the amygdala and hippocampus (1) encoded high-level social traits such as perceived facial trustworthiness and dominance and this response was modulated by task instructions; (2) encoded low-level facial features and demonstrated region-based feature coding, which was not modulated by task instructions; and (3) encoded fixations on salient face parts such as the eyes and mouth, which was not modulated by task instructions. Together, our results provide a comprehensive survey of task modulation of neural processes underlying face perception at the single-neuron level in the human amygdala and hippocampus.

Encoding of facial features by single neurons in the human amygdala and hippocampus.

Faces are salient social stimuli that attract a stereotypical pattern of eye movement. The human amygdala and hippocampus are involved in various aspects of face processing; however, it remains unclear how they encode the content of fixations when viewing faces. To answer this question, we employed single-neuron recordings with simultaneous eye tracking when participants viewed natural face stimuli. We found a class of neurons in the human amygdala and hippocampus that encoded salient facial features such as the eyes and mouth. With a control experiment using non-face stimuli, we further showed that feature selectivity was specific to faces. We also found another population of neurons that differentiated saccades to the eyes vs. the mouth. Population decoding confirmed our results and further revealed the temporal dynamics of face feature coding. Interestingly, we found that the amygdala and hippocampus played different roles in encoding facial features. Lastly, we revealed two functional roles of feature-selective neurons: 1) they encoded the salient region for face recognition, and 2) they were related to perceived social trait judgments. Together, our results link eye movement with neural face processing and provide important mechanistic insights for human face perception.

Deep brain stimulation of the nucleus accumbens/ventral capsule for severe and intractable opioid and benzodiazepine use disorder.

Given high relapse rates and the prevalence of overdose deaths, novel treatments for substance use disorder (SUD) are desperately needed for those who are treatment refractory. The objective of this study was to evaluate the safety of deep brain stimulation (DBS) for SUD and the effects of DBS on substance use, substance craving, emotional symptoms, and frontal/executive functions. DBS electrodes were implanted bilaterally within the Nucleus Accumbens/Ventral anterior internal capsule (NAc/VC) of a man in his early 30s with >10-year history of severe treatment refractory opioid and benzodiazepine use disorders. DBS of the NAc/VC was found to be safe with no serious adverse events noted and the participant remained abstinent and engaged in comprehensive treatment at the 12-week endpoint (and 12-month extended follow-up). Using a 0-100 visual analog scale, substance cravings decreased post-DBS implantation; most substantially in benzodiazepine craving following the final DBS titration (1.0 ± 2.2) compared to baseline (53.4 ± 29.5; p < .001). A trend toward improvement in frontal/executive function was observed on the balloon analog risk task performance following the final titration (217.7 ± 76.2) compared to baseline (131.3 ± 28.1, p = .066). FDG PET demonstrated an increase in glucose metabolism in the dorsolateral prefrontal and medial premotor cortices at the 12-week endpoint compared to post-surgery/pre-DBS titration. Heart Rate Variability (HRV) improved following the final titration (rMSSD = 56.0 ± 11.7) compared to baseline (19.2 ± 8.2; p < .001). In a participant with severe, treatment refractory opioid and benzodiazepine use disorder, DBS of the NAc/VC was safe, reduced substance use and craving, and improved frontal and executive functions. Confirmation of these findings with future studies is needed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Trepanation of the Outer Table as a Treatment for Scalping Injuries: Historical Perspective and Modern Applications.

Complex cranial wounds represent complex surgical problems. In modern times, these are mostly due to accidental trauma. During the period of the American Frontier, violent scalping was a common practice. Innovative techniques were utilized to improve outcomes for this condition that still have relevance in today's practice. We provide a historical perspective with vignettes that identify survivors of violent scalping from the American Frontier as well as the surgical techniques used to treat them. The techniques identified were then modified for modern practice and applied to a complex cranial wound. A review of primary and secondary historical sources was carried out. Nine separate incidences of violent scalping were identified from this period. Successful treatment relied on exposure of the diploe leading to granulation tissue formation and eventual scalp coverage. This was accomplished as a byproduct of the violence of the scalping or as an application of the technique first described by Augustin Belloste in 1696. Application of this technique in a modern setting may allow for improved wound healing. Trepanation of the outer table to aid in healing and closure of complex cranial wounds has a long history of successful practice and can be successfully applied to modern practice.

Surgical Technique and Patient Selection for Spinal Cord Stimulation for Chronic Pain.

Spinal cord stimulation (SCS) is a neuromodulation surgical technique that allows the treatment of various causes of chronic pain. SCS is effective in the treatment of chronic low back pain, neuropathic pain, chronic regional pain syndrome, and failed back surgery syndrome, among others. The mechanisms underlying the efficacy are still under investigation and different mechanisms are likely responsible for the effects of different waveforms used in the therapy. Successful application of SCS to individual patients depends on patient selection and meticulous surgical technique. Important factors in patient selection depend on preoperative imaging, maximizing noninvasive therapy, and neuropsychological evaluation. Percutaneous and open techniques exist for placing both paddle-shaped epidural leads as well as typical cylindrical leads. Benefits and risks exist for both techniques and the exact technique that is optimal depends on surgeon experience and surgeon and patient preference. Complications are rare and can be minimized and managed with appropriate preoperative mitigation.

Neuromodulation Therapies for Spasticity Control: Now and Beyond.

Spasticity is a major cause of disability following upper motor neuron (UMN) injury. The diagnosis and treatment of spasticity has been a focus of clinicians and researchers alike. In recent years, there have been significant advances both in strategies for spasticity assessment and in the development of novel treatments. Currently, several well-established spasticity management techniques fall into the major categories of physiotherapy, pharmacotherapy, and surgical management. The majority of recent developments in all of these broad categories have focused more on methods of neuromodulation instead of simple symptomatic treatment, attempting to address the underlying cause of spasticity more directly. The following narrative review briefly discusses the causes and clinical assessment of spasticity and also details the wide variety of current and developing treatment approaches for this often-debilitating condition.

Patient Acceptability of the Use of Advanced Practice Providers in an Outpatient Neurosurgery Clinic.

Introduction Increasing demands for healthcare manpower has necessitated the utilization of advanced practice providers (APPs). The effect of APPs in primary care has been well-characterized but is less studied in surgical subspecialties. The objective of this study is to assess the patient acceptability of APPs in an outpatient neurosurgery setting. Methods We conducted a prospective, survey-based study among 78 adult patients in the neurosurgical outpatient clinic. The survey consisted of 10 questions assessing the hypothetical acceptability of care provided by neurosurgeons and APPs. These were compared as pre-specified dyads, with patients blinded to dyad composition. The data were analyzed with Chi-square tests. Results Patients preferred to see their neurosurgeon for their first clinic visit even with a longer lag time (29% acceptability difference, p = 0.012). Patients also preferred to see the neurosurgeon for their first postoperative visit (20% difference, p = 0.009). For all visits, patients preferred to see an APP if the clinic visit would be on time, rather than see the surgeon with a significant delay (30% difference, p = 0.0002). If their visit was scheduled with an APP, patients preferred that the neurosurgeon review their treatment plan before they left the clinic (15% difference, p = 0.04). Overall, seeing an APP was acceptable if patients were informed ahead of time (37% difference, p < 0.0001). Conclusions Team-based care utilizing APPs is acceptable to patients. Patients had strong preferences for seeing their surgeon for the first neurosurgical clinic visit and first post-operative visit. Patients were satisfied with seeing an APP if they could be seen more expeditiously. Patients also preferred to know ahead of time if they were going to see an APP.