Biomedical Engineering - Research Publications

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    The Effects of Cathodal Transcranial Direct Current Stimulation in a Patient with Drug-Resistant Temporal Lobe Epilepsy (Case Study)
    Zoghi, M ; O'Brien, TJ ; Kwan, P ; Cook, MJ ; Galea, M ; Jaberzadeh, S (ELSEVIER SCIENCE INC, 2016)
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    P015 The effects of cathodal transcranial direct current stimulation in patienst with focal epilepsy (a pilot study)‘
    Zoghi, M ; Cook, M ; O’Brien, T ; Kwan, P ; Jaberzadeh, S ; Galea, M (Elsevier, 2017-03)
    Introduction: Over 65 million people live with epilepsy worldwide. Unfortunately, seizures can not be adequately controlled in a third of the affected individuals. Therefore, there is a definite need for adjunctive or alternative therapeutic approaches in this group of patients to control the recurrence of seizure attacks. Modulation of dysfunctional electrical brain activity by transcranial direct current stimulation (tDCS) seems to be a potentially valuable non-invasive alternative for epilepsy treatment in this population. Objectives: This pilot study aimed to assess the effects of a novel protocol called within-session repeated c-tDCS (9 min treatment - 20 min rest - 9 min treatment) on patients with focal epilepsy. Method: We conducted a small pilot study in patients admitted to the Video-EEG Monitoring Unit at the Royal Melbourne Hospital and as out patients at this hospital or St Vincent Hospital. Thirty patients have participated in this study to date. Twenty patients with focal epilepsy received one session of c-tDCS (9–20-9 protocol) over the temporal lobe in the affected hemisphere. One participant received c-tDCS on two consecutive days. The other nine patients received one session of sham tDCS with the same electrode montage and protocol. Short interval intracortical inhibition or SICI was measured with paired-pulse transcranial magnetic stimulation (TMS) before and after the tDCS intervention in 18 participants. Motor evoked potentials were recorded from first dorsal interosseous muscle in these participants. Participants were asked to record the time and the number of their seizures post tDCS treatment for 4 weeks in a seizure diary. Twenty-four participants returned their diaries. Results: All patients tolerated the c-tDCS protocol very well. One-way ANOVA showed that SICI was increased significantly in the experimental group compared to the sham group (F = 10.3, p = 0.005) (Fig. 1). The mean response ratio was −48.4 (SD = 54) for the experimental group vs. −8.3 (SD = 16.7) for sham group
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    Electrical probing of cortical excitability in patients with epilepsy
    Freestone, DR ; Kuhlmann, L ; Grayden, DB ; Burkitt, AN ; Lai, A ; Nelson, TS ; Vogrin, S ; Murphy, M ; D'Souza, W ; Badawy, R ; Nesic, D ; Cook, MJ (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2011-12)
    Standard methods for seizure prediction involve passive monitoring of intracranial electroencephalography (iEEG) in order to track the 'state' of the brain. This paper introduces a new method for measuring cortical excitability using an electrical probing stimulus. Electrical probing enables feature extraction in a more robust and controlled manner compared to passively tracking features of iEEG signals. The probing stimuli consist of 100 bi-phasic pulses, delivered every 10 min. Features representing neural excitability are estimated from the iEEG responses to the stimuli. These features include the amplitude of the electrically evoked potential, the mean phase variance (univariate), and the phase-locking value (bivariate). In one patient, it is shown how the features vary over time in relation to the sleep-wake cycle and an epileptic seizure. For a second patient, it is demonstrated how the features vary with the rate of interictal discharges. In addition, the spatial pattern of increases and decreases in phase synchrony is explored when comparing periods of low and high interictal discharge rates, or sleep and awake states. The results demonstrate a proof-of-principle for the method to be applied in a seizure anticipation framework. This article is part of a Supplemental Special Issue entitled The Future of Automated Seizure Detection and Prediction.
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    Three-dimensional neural cultures produce networks that mimic native brain activity
    Bourke, JL ; Quigley, AF ; Duchi, S ; O'Connell, CD ; Crook, JM ; Wallace, GG ; Cook, MJ ; Kapsa, RMI (WILEY, 2018-02)
    Development of brain function is critically dependent on neuronal networks organized through three dimensions. Culture of central nervous system neurons has traditionally been limited to two dimensions, restricting growth patterns and network formation to a single plane. Here, with the use of multichannel extracellular microelectrode arrays, we demonstrate that neurons cultured in a true three-dimensional environment recapitulate native neuronal network formation and produce functional outcomes more akin to in vivo neuronal network activity.
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    Deep brain stimulation for drug-resistant epilepsy
    Li, MCH ; Cook, MJ (WILEY, 2018-02)
    OBJECTIVES: To review clinical evidence on the antiepileptic effects of deep brain stimulation (DBS) for drug-resistant epilepsy, its safety, and the factors influencing individual outcomes. METHODS: A comprehensive search of the medical literature (PubMed, Medline) was conducted to identify relevant articles investigating DBS therapy for drug-resistant epilepsy. Reference lists of these articles were used to source further articles. RESULTS: Stimulation of the anterior nucleus of the thalamus (ANT) and hippocampus (HC) has been shown to decrease the frequency of refractory seizures. Half of all patients from clinical studies experienced a 46%-90% seizure reduction with ANT-DBS, and a 48%-95% seizure reduction with HC-DBS. The efficacy of stimulating other targets remains inconclusive due to lack of evidence. Approximately three-fourths of patients receiving ANT, HC, or centromedian nucleus of the thalamus (CMT) stimulation are responders-experiencing a seizure reduction of at least 50%. The time course of clinical benefit varies dramatically, with both an initial lesional effect and ongoing stimulation effect at play. Improved quality of life and changes to cognition or mood may also occur. Side effects are similar in nature to those reported from DBS therapy for movement disorders. Several factors are potentially associated with stimulation efficacy, including an absence of structural abnormality on imaging for ANT and HC stimulation, and electrode position relative to the target. Certain seizure types or syndromes may respond more favorably to specific targets, including ANT stimulation for deep temporal or limbic seizures, and CMT stimulation for generalized seizures and Lennox-Gastaut syndrome. SIGNIFICANCE: We have identified several patient, disease, and stimulation factors that potentially predict seizure outcome following DBS. More large-scale clinical trials are needed to explore different stimulation parameters, reevaluate the indications for DBS, and identify robust predictors of patient response.
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    When can we trust responders? Serious concerns when using 50% response rate to assess clinical trials
    Karoly, PJ ; Romero, J ; Cook, MJ ; Freestone, DR ; Goldenholz, DM (Wiley, 2019-09-01)
    Individual seizure rates are highly volatile, with large fluctuations from month‐to‐month. Nevertheless, changes in individual mean seizure rates are used to measure whether or not trial participants successfully respond to treatment. This study aims to quantify the challenges in identifying individual treatment responders in epilepsy. A power calculation was performed to determine the trial duration required to detect a significant 50% decrease in seizure rates (P < .05) for individuals. Seizure rate simulations were also performed to determine the number of people who would appear to be 50% responders by chance. Seizure rate statistics were derived from long‐term seizure counts recorded during a previous clinical trial for an implantable seizure monitoring device. We showed that individual variance in monthly seizure rates can lead to an unacceptably high false‐positive rate in the detection of individual treatment responders. This error rate cannot be reduced by increasing the trial population; however, it can be reduced by increasing the duration of clinical trials. This finding suggests that some drugs may be incorrectly evaluated as effective; or, conversely, that helpful drugs could be rejected based on 50% response rates. It is important to pursue more nuanced approaches to measuring individual treatment response, which consider the patient‐specific distributions of seizure rates.
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    A decision tree to determine fitness to drive in epilepsy: Results of a pilot in two Australian states
    Somerville, ER ; Somerville, E ; Black, A ; Lander, C ; Jones, D ; Beran, R ; Gordon, J ; Burrow, J ; Archer, J ; Dunne, J ; Cook, M ; Berkovic, S ; Harvey, S (WILEY, 2019-07)
    OBJECTIVE: Certification by treating physicians of fitness to drive in people with epilepsy creates a conflict of interest that may result in unsafe decisions, damage the doctor-patient relationship, expose the physician to legal liability and prevent optimal treatment. Ideally, the treating physician should provide objective clinical information to the driver licensing authority (DLA), which then determines fitness or otherwise. However, DLAs in Australia do not employ medical staff and the national standards are complex. Fitness is determined by the treating physician, according to published national standards. The purpose of this study was to determine the feasibility of using a decision tree to determine fitness, according to the Australian standards. METHODS: A decision tree was constructed to use clinical data to determine whether a patient met the national standard to drive a private motorcar, failed to meet it or required further assessment. A form was designed to collect the necessary clinical data from the treating physician. A computerized version of the decision tree was then used in a pilot in two Australian states in parallel with the existing certification system. Four hundred thirty-nine drivers with declared epilepsy and their treating physicians were invited to participate when their annual driver licence review was due. RESULTS: Two hundred fifty-three (58%) forms were returned. All patients were considered fit to drive by their physician. Seventy-six percent had not had a seizure for over two years. In 88.1%, there was agreement between the decision tree and treating physician, with 3.6% identified by the decision tree as requiring review. Although considered fit by their physician, 6.3% did not meet the national standard to drive. SIGNIFICANCE: The decision tree model is a practical alternative to fitness certification by treating physicians. This Australian pilot can serve as a model for applying objective standards to driving assessments in other jurisdictions, using local driving standards. It has the potential to improve road safety by avoiding the negative effects of certification by treating physicians and can cope with complex standards. It is now in use in two states of Australia.
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    Etiologies and characteristics of refractory status epilepticus cases in different areas of the world: Results from a global audit
    Ferlisi, M ; Hocker, S ; Trinka, E ; Shorvon, S (WILEY, 2018-10)
    To describe the demographics, etiologies, types of status epilepticus (SE), and outcomes in people with refractory and super-refractory SE from around the world, we prospectively collected cases of refractory SE (RSE) treated with continuous intravenous anesthetic drugs in an intensive care unit setting through online questionnaires using "active surveillance." We collected information about 776 cases of RSE in 50 countries over 4 years. Control of SE was achieved in 74% of the cases. Neurologic outcomes were poor in 41% of patients, and 24% died. Good outcome was associated with younger age and a history of epilepsy. Etiology strongly influenced the outcome. Patients from Asia were younger, more frequently presented with convulsive SE, and were more frequently affected by infectious etiologies when compared with patients from Europe and the Americas. Despite these differences, outcomes were similar in all countries. Demographics of patients with RSE in a global audit are similar to those in prior single center series, providing evidence of generalizability of those studies. Important differences exist among patients with RSE from different regions of the world, but these do not seem to significantly influence patient outcomes.
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    Single-fiber F waves compared with conventional surface F waves, and their utility in detecting early diabetic neuropathy
    Kamel, J ; Knight-Sadler, R ; Cook, M ; Roberts, L (WILEY, 2018-11)
    INTRODUCTION: The single-fiber F-wave (SFF-wave) technique assesses the entire length of single motor fibers using a concentric needle. Herein we investigated the utility of this approach in the detection of early diabetes-related neuropathy, and compared it with the use of conventional surface F waves (CF waves). METHODS: Sixteen patients with diabetes and either no neuropathy or mild neuropathy were assessed and compared with 16 age- and height-matched control participants. RESULTS: Both CF and SFF waves were abnormal in all 5 patients who had mild neuropathy. However, SFF waves demonstrated subclinical abnormalities in 7 of 11 patients (64%) with no neuropathy, whereas only 2 of these patients (18%) had prolonged CF waves. Minimum F-wave latency was comparable between techniques, but maximum SFF-wave latency was more frequently prolonged, as these delayed motor units were better isolated, rather than buried among summated CF-wave responses. DISCUSSION: SFF waves highlight the segmental involvement in diabetic neuropathy, and use of the SFF-wave technique detects more abnormalities than with CF waves. Muscle Nerve 58: 665-670, 2018.
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