A longitudinal clinical and spect scan study on HIV-infected patients with new onset seizures and no identifiable cause

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, in fulfillment of the requirements for the degree of Doctor of Philosophy Johannesburg 2015New onset seizures associated with HIV infection have been studied. The data investigating new onset seizures in HIV infected individuals have predominantly originated from developed countries and prior to the availability of anti-retroviral therapy. No longitudinal studies have been conducted. The HIV pandemic has its roots in Africa and South Africa currently bears the brunt of the burden. This study sought to evaluate the current profile of HIV infected individuals presenting with new onset seizures in the South African setting, and to follow up patients in whom no cause is identifiable at baseline. Two hundred Black African patients were recruited from the three major teaching hospitals affiliated to the University of the Witwatersrand, Johannesburg. They had clinical assessments and were extensively investigated to determine a cause for the seizure. In the present study the majority of HIV infected patients with new onset seizures had an underlying cause, the most common of which were meningitis and focal brain lesions. Infectious aetiologies predominated; specifically in patients with advanced disease i.e. HIV stages 2 and 3. Tuberculosis and cryptococcal infections were the most frequent. This is consistent with the prevalent infections in our region. Our patients had advanced immune-suppression as evidenced by the mean CD4 count of 167 μμL. HAART coverage was sub-optimal with the majority of HAART-eligible patients not accessing therapy. The predominant seizure type was generalized tonic-clonic. Neuroimaging abnormalities were present in most patients. Fifteen patients with no identifiable cause were enlisted in the long-term study. These patients had repeated clinical assessments; laboratory investigations; MRI and brain SPECT scans. All patients presented with generalized tonic-clonic seizures. Non-specific white matter lesions on MRI; temporal lobe abnormalities on visual SPECT scans and regional cerebral hypo-perfusion on quantitative SPECT scan analysis were common findings. The patients who initiated HAART during the study period improved on laboratory monitoring and on quantitative SPECT analysis. One patient developed HIV associated dementia during follow up. vi New Onset Seizures in HIV infected individuals in whom no cause is identifiable may possibly represent: Early stages of the spectrum of neurocognitive dysfunction seen in HIV infection A precursor for dementia These patients are likely to benefit from the initiation of anti-retroviral therapy.MT201

Patient-specific detection of cerebral blood flow alterations as assessed by arterial spin labeling in drug-resistant epileptic patients

Electrophysiological and hemodynamic data can be integrated to accurately and precisely identify the generators of abnormal electrical activity in drug-resistant focal epilepsy. Arterial Spin Labeling (ASL), a magnetic resonance imaging (MRI) technique for quantitative noninvasive measurement of cerebral blood flow (CBF), can provide a direct measure of variations in cerebral perfusion associated with the epileptic focus. In this study, we aimed to confirm the ASL diagnostic value in the identification of the epileptogenic zone, as compared to electrical source imaging (ESI) results, and to apply a template-based approach to depict statistically significant CBF alterations. Standard video-electroencephalography (EEG), high-density EEG, and ASL were performed to identify clinical seizure semiology and noninvasively localize the epileptic focus in 12 drug-resistant focal epilepsy patients. The same ASL protocol was applied to a control group of 17 healthy volunteers from which a normal perfusion template was constructed using a mixed-effect approach. CBF maps of each patient were then statistically compared to the reference template to identify perfusion alterations. Significant hypo- and hyperperfused areas were identified in all cases, showing good agreement between ASL and ESI results. Interictal hypoperfusion was observed at the site of the seizure in 10/12 patients and early postictal hyperperfusion in 2/12. The epileptic focus was correctly identified within the surgical resection margins in the 5 patients who underwent lobectomy, all of which had good postsurgical outcomes. The combined use of ESI and ASL can aid in the noninvasive evaluation of drug-resistant epileptic patients

Imaging in neurological and vascular brain diseases (SPECT and SPECT/CT)

Since the first in vivo studies of cerebral function with radionuclides by Ingvar and Lassen, nuclear medicine (NM) brain applications have evolved dramatically, with marked improvements in both methods and tracers. Consequently it is now possible to assess not only cerebral blood flow and energy metabolism but also neurotransmission. Planar functional imaging was soon substituted by single-photon emission computed tomography (SPECT) and positron emission tomography (PET); it now has limited application in brain imaging, being reserved for the assessment of brain death

Narrative review of epilepsy: getting the most out of your neuroimaging

Neuroimaging represents an important step in the evaluation of pediatric epilepsy. The crucial role of brain imaging in the diagnosis, follow-up and presurgical assessment of patients with epilepsy is noted and has to be familiar to all neuroradiologists and trainees approaching pediatric brain imaging. Morphological qualitative imaging shows the majority of cerebral lesions/alterations underlying focal epilepsy and can highlight some features which are useful in the differential diagnosis of the different types of epilepsy. Recent advances in MRI acquisitions including diffusion-weighted imaging (DWI), post-acquisition image processing techniques, and quantification of imaging data are increasing the accuracy of lesion detection during the last decades. Functional MRI (fMRI) can be really useful and helps to identify cortical eloquent areas that are essential for language, motor function, and memory, and diffusion tensor imaging (DTI) can reveal white matter tracts that are vital for these functions, thus reducing the risk of epilepsy surgery causing new morbidities. Also positron emission tomography (PET), single photon emission computed tomography (SPECT), simultaneous electroencephalogram (EEG) and fMRI, and electrical and magnetic source imaging can be used to assess the exact localization of epileptic foci and help in the design of intracranial EEG recording strategies. The main role of these “hybrid” techniques is to obtain quantitative and qualitative informations, a necessary step to evaluate and demonstrate the complex relationship between abnormal structural and functional data and to manage a “patient-tailored” surgical approach in epileptic patients

Visual hypo and hypergnosia as exemplars of poles of psychic tonus in the occipital lobes: Multiple case analyses

Abstract. The "psychic tonus" model or PT