Clinical Utility of Sleep Recordings During Presurgical Epilepsy Evaluation With Stereo-Electroencephalography: A Systematic Review.

Although the role of sleep in modulating epileptic activity is well established, many epileptologists overlook the significance of considering sleep during presurgical epilepsy evaluations in cases of drug-resistant epilepsy. Here, we conducted a comprehensive literature review from January 2000 to May 2023 using the PubMed electronic database and compiled evidence to highlight the need to revise the current clinical approach. All articles were assessed for eligibility by two independent reviewers.

Intracerebral Dynamics of Sleep Arousals: A Combined Scalp-Intracranial EEG Study.

As an intrinsic component of sleep architecture, sleep arousals represent an intermediate state between sleep and wakefulness and are important for sleep-wake regulation. They are defined in an all-or-none manner, whereas they actually present a wide range of scalp-electroencephalography (EEG) activity patterns. It is poorly understood how these arousals differ in their mechanisms.

Rapid eye movement sleep affects interictal epileptic activity differently in mesiotemporal and neocortical areas.

Objective: Rapid eye movement (REM) sleep reduces the rate and extent of interictal epileptiform discharges (IEDs). Breakthrough epileptic activity during REM sleep is therefore thought to best localize the seizure onset zone (SOZ). We utilized polysomnography combined with direct cortical recordings to investigate the influences of anatomical locations and the time of night on the suppressive effect of REM sleep on IEDs.

The Differing Effects of Sleep on Ictal and Interictal Network Dynamics in Drug-Resistant Epilepsy.

Objective: Sleep has important influences on focal interictal epileptiform discharges (IEDs), and the rates and spatial extent of IEDs are increased in non-rapid eye movement (NREM) sleep. In contrast, the influence of sleep on seizures is less clear, and its effects on seizure topography are poorly documented. We evaluated the influences of NREM sleep on ictal spatiotemporal dynamics and contrasted these with interictal network dynamics.

Primary headache types in adult epilepsy patients.

Background: Headache is among the most common comorbidities in epilepsy. This study examined the distribution of different primary headache disorders in a large cohort of patients with diagnosed epilepsy. Headache types were analysed with regard to gender, type of epilepsy and antiepileptic drugs (AEDs).

Imaging slow brain activity during neocortical and hippocampal epileptiform events with electrical impedance tomography.

Objective: Electrical impedance tomography (EIT) is an imaging technique that produces tomographic images of internal impedance changes within an object using surface electrodes. It can be used to image the slow increase in cerebral tissue impedance that occurs over seconds during epileptic seizures, which is attributed to cell swelling due to disturbances in ion homeostasis following hypersynchronous neuronal firing and its associated metabolic demands. In this study, we characterised and imaged this slow impedance response during neocortical and hippocampal epileptiform events in the rat brain and evaluated its relationship to the underlying neural activity.

Optimised induction of on-demand focal hippocampal and neocortical seizures by electrical stimulation.

Background: Epilepsy is a common neurological disorder affecting over 60 million people globally, approximately a third of whom are refractory to pharmacotherapy. Surgical resection of the epileptogenic zone is frequently unsuitable or ineffective, particularly for individuals with focal neocortical or mesial temporal lobe epilepsy. Therefore, there is a need to develop animal models for elucidating the mechanisms of focal epilepsies and evaluating novel treatment strategies.

In vivo imaging of deep neural activity from the cortical surface during hippocampal epileptiform events in the rat brain using electrical impedance tomography.

Electrical impedance tomography (EIT) is a medical imaging technique which reconstructs images of the internal impedance changes within an object using non-penetrating surface electrodes. To date, EIT has been used to image fast neural impedance changes during somatosensory evoked potentials and epileptiform discharges through the rat cerebral cortex with a resolution of 2 ​ms and <300 ​μm. However, imaging of neural activity in subcortical structures has never been achieved with this technique.

Comparison of Xpert MTB/RIF with AFB smear and AFB culture in suspected cases of paediatric tuberculosis in a tertiary care hospital, Karachi.

Objective: To evaluate the sensitivity, specificity, positive predictive and negative predictive values of Xpert mycobacterium tuberculosis and resistance to rifampicin by comparing it with acid-fast bacilli smear and culture in suspected tuberculosis patients.

Methods: The retrospective study was conducted at the Aga Khan University Hospital, Karachi, and comprised patient data from January 2013 to December 2016. Data related to children with clinical suspicion of pulmonary and extra-pulmonary tuberculosis based on Modified Kenneth Jones criteria, aged 1 month to 18 years whose samples (respiratory or non-respiratory) were sent for Xpert mycobacterium tuberculosis and resistance to rifampicin and acid-fast bacilli smear and culture con currently.

Investigating the safety of fast neural electrical impedance tomography in the rat brain.

Objective: Electrical impedance tomography (EIT) can be used to image impedance changes which arise due to fast electrical activity during neuronal depolarisation and so holds therapeutic potential for improving the localisation of epileptic seizure foci in patients with treatment-resistant epilepsy to aid surgical resection of epileptogenic tissue. Prolonged cortical stimulation may, however, induce neural injury through excitotoxicity and electrochemical reactions at the tissue-electrode interface. The purpose of this work was to assess whether current levels used in fast neural EIT studies induce histologically detectable tissue damage when applied continuously to the rat cerebral cortex.

Imaging fast electrical activity in the brain during ictal epileptiform discharges with electrical impedance tomography.

Electrical Impedance Tomography (EIT) is an emerging medical imaging technique which can produce tomographic images of internal impedance changes within an object using non-penetrating surface electrodes. It has previously been used to image impedance changes due to neuronal depolarisation during evoked potentials in the rat somatosensory cortex with a resolution of 2 ms and <200 μm, using an epicortical electrode array. The purpose of this work was to use this technique to elucidate the intracortical spatiotemporal trajectory of ictal spike-and-wave discharges (SWDs), induced by electrical stimulation in an acute rat model of epilepsy, throughout the cerebral cortex.

Imaging fast neural traffic at fascicular level with electrical impedance tomography: proof of principle in rat sciatic nerve.

Objective: Understanding the coding of neural activity in nerve fascicles is a high priority in computational neuroscience, electroceutical autonomic nerve stimulation and functional electrical stimulation for treatment of paraplegia. Unfortunately, it has been little studied as no technique has yet been available to permit imaging of neuronal depolarization within fascicles in peripheral nerve.

Approach: We report a novel method for achieving this, using a flexible cylindrical multi-electrode cuff placed around nerve and the new medical imaging technique of fast neural electrical impedance tomography (EIT).

Frequency-dependent characterisation of impedance changes during epileptiform activity in a rat model of epilepsy.

Objective: Electrical impedance tomography (EIT) can be used to image impedance changes associated with epileptiform activity and so holds therapeutic potential for improving presurgical localisation of the ictal onset zone in patients with treatment-resistant epilepsy. There are two principal impedance changes which occur during seizures that may be imaged with EIT: (a) a fast, transient impedance decrease over milliseconds due to hypersynchronous neuronal depolarisation in individual ictal discharges; and (b) a larger, slow impedance increase caused by cell swelling over the course of the seizure. The magnitude of these signals is highly dependent on the carrier frequency of applied current used for obtaining impedance measurements.

Feasibility of imaging evoked activity throughout the rat brain using electrical impedance tomography.

Electrical Impedance Tomography (EIT) is an emerging technique which has been used to image evoked activity during whisker displacement in the cortex of an anaesthetised rat with a spatiotemporal resolution of 200 μm and 2 ms. The aim of this work was to extend EIT to image not only from the cortex but also from deeper structures active in somatosensory processing, specifically the ventral posterolateral (VPL) nucleus of the thalamus. The direct response in the cortex and VPL following 2 Hz forepaw stimulation were quantified using a 57-channel epicortical electrode array and a 16-channel depth electrode.

Characterising the frequency response of impedance changes during evoked physiological activity in the rat brain.

Objective: Electrical impedance tomography (EIT) can image impedance changes associated with evoked physiological activity in the cerebral cortex using an array of epicortical electrodes. An impedance change is observed as the externally applied current, normally confined to the extracellular space is admitted into the conducting intracellular space during neuronal depolarisation. The response is largest at DC and decreases at higher frequencies due to capacitative transfer of current across the membrane.

Thalassemia and premarital screening: potential for implementation of a screening program among young people in Pakistan.

Pakistan has a high prevalence of β-thalassemia (β-thal) but lacks a screening program for its prevention. This questionnaire-based cross-sectional study was conducted in six randomly chosen non medical universities to assess the students' knowledge of β-thal and premarital screening, and their attitude towards such a program. Comparison was made between the respondents' attitude towards premarital screening before and after providing them some information regarding the disease.