Definition of Implanted Neurological Device Abandonment: A Systematic Review and Consensus Statement.

Importance: Establishing a formal definition for neurological device abandonment has the potential to reduce or to prevent the occurrence of this abandonment. Objective: To perform a systematic review of the literature and develop an expert consensus definition for neurological device abandonment. Evidence Review: After a Royal Society Summit on Neural Interfaces (September 13-14, 2023), a systematic English language review using PubMed was undertaken to investigate extant definitions of neurological device abandonment. Articles were reviewed for relevance to neurological device abandonment in the setting of deep brain, vagal nerve, and spinal cord stimulation. This review was followed by the convening of an expert consensus group of physicians, scientists, ethicists, and stakeholders. The group summarized findings, added subject matter experience, and applied relevant ethics concepts to propose a current operational definition of neurological device abandonment. Data collection, study, and consensus development were done between September 13, 2023, and February 1, 2024. Findings: The PubMed search revealed 734 total articles, and after review, 7 articles were found to address neurological device abandonment. The expert consensus group addressed findings as germane to neurological device abandonment and added personal experience and additional relevant peer-reviewed articles, addressed stakeholders' respective responsibilities, and operationally defined abandonment in the context of implantable neurotechnological devices. The group further addressed whether clinical trial failure or shelving of devices would constitute or be associated with abandonment as defined. Referential to these domains and dimensions, the group proposed a standardized definition for abandonment of active implantable neurotechnological devices. Conclusions and Relevance: This study's consensus statement suggests that the definition for neurological device abandonment should entail failure to provide fundamental aspects of patient consent; fulfill reasonable responsibility for medical, technical, or financial support prior to the end of the device's labeled lifetime; and address any or all immediate needs that may result in safety concerns or device ineffectiveness and that the definition of abandonment associated with the failure of a research trial should be contingent on specific circumstances.

Towards Real-time Multiplexed Bioimpedance Tumour-Tissue Margin Analysis.

Bioimpedance varies with physical tissue characteristics. As such it can be used for real-time tissue discrimination. This has led to its application as a surgical mapping tool to differentiate between healthy and abnormal tissue intraoperatively during tumour resection. Here, we build on previous work implementing a probe-based tetrapolar bioimpedance systems demonstrator, now extracting additional information for margin analysis with imperfect bioimpedance visibility. Through finite element analysis, we show preliminary findings using a single measurement with a multiplexed tetrapolar bioimpedance probe for identifying tissue boundaries, applied to porcine tissue as a surrogate for a tumour-tissue interface.

Volitional Control of Brain Motor Activity and Its Therapeutic Potential.

BACKGROUND: Neurofeedback training is a closed-loop neuromodulatory technique in which real-time feedback of brain activity and connectivity is provided to the participant for the purpose of volitional neural control. Through practice and reinforcement, such learning has been shown to facilitate measurable changes in brain function and behavior. OBJECTIVES: In this review, we examine how neurofeedback, coupled with motor imagery training, has the potential to improve or normalize motor function in neurological diseases such as Parkinson disease and chronic stroke. We will also explore neurofeedback in the context of brain-machine interfaces (BMIs), discussing both noninvasive and invasive methods which have been used to power external devices (eg, robot hand orthosis or exoskeleton) in the context of motor neurorehabilitation. CONCLUSIONS: The published literature provides mounting high-quality evidence that neurofeedback and BMI control may lead to clinically relevant changes in brain function and behavior.

Olfactory outcomes after transsphenoidal endonasal surgery.

Background: The endonasal approach is the gold standard for the resection of pituitary tumours, with either microscopic endonasal transsphenoidal (MET) or endoscopic endonasal transsphenoidal (EET) technique. Advantages and disadvantages of both techniques have been widely described in the literature, although limited attention has been paid to its impact on the sense of smell.Objective: The present study aims to quantify the effect of transnasal surgery on pituitary patients and examine olfactory outcomes.Methods: A prospective cohort study assessing the sense of smell of 20 patients (10 MET and 10 EET) pre-operatively. Olfactory function was re-assessed 6 months after surgery, using the University of Pennsylvania Smell Identification Test (Sensonics Inc., Haddon Heights, NJ).Results: The UPSIT (Sensonics Inc.) results showed a median pre-operative score of 33 (IQR 31-37.5) (normosmia). The median post-operative result was 25 (IQR 19.5-32), consistent with moderate microsmia. Twenty percent of the patients had normal olfactory function post-operatively, all of whom were from the EET group. Twenty percent had mild microsmia, equally divided in MET and EET subgroups. Seven patients had severe microsmia. Four patients were completely anosmic at 6 months follow-up.Conclusions: Patients undergoing a transsphenoidal procedure are at risk of olfactory disturbance post-operatively, which may include loss of the sense of smell. This information is relevant to the patients' perioperative experience, and should be incorporated into counselling with regards to outcomes and expectations. Although the study size is small, the study results suggest the ETS technique may be less traumatic for the olfactory function. A larger study powered to fully examine potential differences in olfactory outcomes following ETS and MTS is warranted.

Volitional modulation of higher-order visual cortex alters human perception.

Can we change our perception by controlling our brain activation? Awareness during binocular rivalry is shaped by the alternating perception of different stimuli presented separately to each monocular view. We tested the possibility of causally influencing the likelihood of a stimulus entering awareness. To do this, participants were trained with neurofeedback, using realtime functional magnetic resonance imaging (rt-fMRI), to differentially modulate activation in stimulus-selective visual cortex representing each of the monocular images. Neurofeedback training led to altered bistable perception associated with activity changes in the trained regions. The degree to which training influenced perception predicted changes in grey and white matter volumes of these regions. Short-term intensive neurofeedback training therefore sculpted the dynamics of visual awareness, with associated plasticity in the human brain.

Real-time decoding of covert attention in higher-order visual areas.

Brain-computer-interfaces (BCI) provide a means of using human brain activations to control devices for communication. Until now this has only been demonstrated in primary motor and sensory brain regions, using surgical implants or non-invasive neuroimaging techniques. Here, we provide proof-of-principle for the use of higher-order brain regions involved in complex cognitive processes such as attention. Using realtime fMRI, we implemented an online 'winner-takes-all approach' with quadrant-specific parameter estimates, to achieve single-block classification of brain activations. These were linked to the covert allocation of attention to real-world images presented at 4-quadrant locations. Accuracies in three target regions were significantly above chance, with individual decoding accuracies reaching upto 70%. By utilising higher order mental processes, 'cognitive BCIs' access varied and therefore more versatile information, potentially providing a platform for communication in patients who are unable to speak or move due to brain injury.

The conversational position in endoscopic pituitary surgery.

We describe a novel patient position for endoscopic transphenoidal surgery - the 'conversational position'. This position is a safe and effective alternative to the standard supine position, incorporating a semi-sitting position with the additional innovation of achieving a 'conversational position' by flexing the neck and turning the patient's head turned to face the surgeon. The 'conversational' position offers improvements in the surgical approach to sellar region, addressing specific intraoperative challenges such as maintaining a bloodless operative field, and enabling more intuitive and ergonomic surgical workflow.

Preoperative particle and glue embolization of meningiomas: indications, results, and lessons learned from 117 consecutive patients.

BACKGROUND: Preoperative embolization of meningiomas remains contentious, with persisting uncertainty over the safety and efficacy of this adjunctive technique. OBJECTIVE: To evaluate the safety of presurgical embolization of meningiomas and its impact on subsequent transfusion requirement with respect to the extent of embolization and technique used. METHODS: One hundred seventeen consecutive patients between 2001 and 2010 were referred for embolization of presumed intracranial meningioma before surgical resection. Glue and/or particles were used to devascularize the tumor in 107 patients, all of whom went on to operative resection. The extent and nature of embolization-related complications, degree of angiographic devascularization, and the intraoperative blood transfusion requirements were analyzed. RESULTS: Mean blood transfusion requirement during surgery was 0.8 units per case (range, 1-14 units). Blood transfusion was significantly lower in patients whose meningiomas were completely, angiographically devascularized (P = .035). Four patients had complications as a direct result of the embolization procedure. These included intratumoral hemorrhage in 2, sixth cranial nerve palsy in 1, and scalp necrosis requiring reconstructive surgery in 1 patient. CONCLUSION: The complication rate was 3.7%. No relationship between the embolic agent and the degree of devascularization was observed. Achieving a complete devascularization resulted in a lower blood transfusion requirement, considered an indirect measure of operative blood loss. This series demonstrates that preoperative meningioma embolization is safe and may reduce operative blood loss. We present distal intratumoral injection of liquid embolic as a safe and effective alternative to more established particle embolization techniques.

Use of the novel ANSPACH bone collector for bone autograft in anterior cervical discectomy and cage fusion.

BACKGROUND: The use of interbody cages with bone autograft following anterior cervical discectomy is well documented. The use of high-speed drills in the drilling of the posterior osteophyte results in the production of bone dust with viable osteophytes. We report the use of the ANSPACH bone collector device, which can be connected to standard suction circuitry and used to collect this bone dust. METHOD/RESULTS: A group of six patients undergoing anterior cervical discectomies at one (4) or two levels (2). The bone collector was attached to the suction system. Following collection of the desired bone dust from the devices' collection chambers, it was fitted into the previously sized interbody cages and impacted into the disc spaces. The bone collector is a single-use, disposable device, delivered sterile, designed to connect to standard 6-mm suction tubing. The use of the bone collector provided sufficient bone material for complete filling of the interbody cages in all of the patients. DISCUSSION: The use of autogenous cancellous bone material is the gold standard with regards to bone graft. The collection of bone dust during the use of high-speed drills has a number of applications and could provide a useful source of viable osteogenic material in spinal, cranial and craniofacial procedures. CONCLUSION: The use of the ANSPACH bone collector incorporated into a standard suction system provides an efficient method of autograft collection, removing the need for an adjunctive procedure with associated donor-site morbidity.