Use of ultrasonic aspirator for CNS tumour resection

Ultrasonic aspirator (UA), or the Cavitron Ultrasonic Aspirator (CUSA) as it is commonly referred to, utilizes ultrasonic waves of variable range of frequencies to disintegrate and excise tumours. It is developed as a substitute of bipolar diathermy; a tool commonly employed for coagulation that uses focussed electric current and may damage tissues by virtue of contact, or by the heat that it produces. Over the last 30 years, CUSA has become increasingly popular in several soft tissue surgeries, especially brain and spine tumour resection, as it allows reduction in the use of bipolar diathermy. It is assumed that CUSA improves both surgical safety and clinical outcomes, and also reduces surgical time. Herein the authors have reviewed the available literature on the advantages of CUSA

Management of Intracranial Haemangiopericytomas

Haemangiopericytomas are rare tumours, commonly mistaken as meningiomas on radiology. These tumours are considered malignant and treatment involves aggressive surgery, followed by adjuvant radiation therapy, and close radiological and clinical follow ups. Herein the authors have reviewed the recent literature on the management of these tumours

The transcriptional landscape of age in human peripheral blood

Disease incidences increase with age, but the molecular characteristics of ageing that lead to increased disease susceptibility remain inadequately understood. Here we perform a whole-blood gene expression meta-analysis in 14,983 individuals of European ancestry (including replication) and identify 1,497 genes that are differentially expressed with chronological age. The age-associated genes do not harbor more age-associated CpG-methylation sites than other genes, but are instead enriched for the presence of potentially functional CpG-methylation sites in enhancer and insulator regions that associate with both chronological age and gene expression levels. We further used the gene expression profiles to calculate the 'transcriptomic age' of an individual, and show that differences between transcriptomic age and chronological age are associated with biological features linked to ageing, such as blood pressure, cholesterol levels, fasting glucose, and body mass index. The transcriptomic prediction model adds biological relevance and complements existing epigenetic prediction models, and can be used by others to calculate transcriptomic age in external cohorts.Peer reviewe

Structural changes to the papez memory circuit in neurodegenerative diseases

The Papez circuit is a brain network involved in episodic memory. It is comprised of the cingulate cortices, anterior thalamus, hippocampus, and mammillary bodies. Memory impairment is a core feature in Alzheimer’s disease (AD) and has also been identified in some patients with behavioral variant frontotemporal dementia (bvFTD), amyotrophic lateral sclerosis (ALS) and bvFTD with amyotrophic lateral sclerosis (bvFTD-ALS). Importantly, few studies have assessed the integrity of the Papez circuit in these neurodegenerative diseases. This thesis sets out to do this with the purpose of determining whether degeneration in the Papez circuit is found only in neurodegenerative disorders characterized by episodic memory impairment. Specifically, this thesis examines the integrity of the Papez circuit in postmortem tissue from patients with AD, bvFTD and ALS as well as normal controls without dementia or significant neuropathological abnormalities. We hypothesize that significant atrophy in the relay nodes of the Papez memory circuit will be observed only in AD and bvFTD cases with memory impairment. A total of 7 clinicopathological cohorts comprising 85 cases were studied across two cohort analyses in this thesis. Specifically, the first cohort analysis involved 15 patients with pathologically confirmed clinical AD, 11 patients with clinical AD that were found to have pathological Frontotemporal lobar degeneration (FTLD) at autopsy, 10 patients with clinical bvFTD that were found to have pathological AD at autopsy and 13 controls. The second cohort analysis involved 11 patients with pathologically-confirmed bvFTD, 11 patients with pathologically-confirmed ALS, 14 patients with pathologically-confirmed bvFTD-ALS and 13 controls. The volumes of the regions of interest were determined using established point-counting volumetric methods. As expected, clinical AD and bvFTD cases demonstrated severe atrophy across most Papez circuit regions. With the exception of the hippocampus, no significant atrophy was observed in the Papez circuit in bvFTD-ALS cases. Degeneration in the Papez circuit was also not observed in ALS cases. This study confirms that degeneration in the Papez circuit is found in AD and bvFTD cases without ALS. Future studies in larger cohorts are needed to compare the type and extent of memory degeneration in bvFTD cases with and without ALS

Intraoperative mapping and preservation of executive functions in awake craniotomy: A systematic review

Awake craniotomy (AC) allows intraoperative brain mapping (ioBM) for maximum lesion resection while monitoring and preserving neurological function. Conventionally, language, visuospatial assessment, and motor functions are mapped, while the assessment of executive functions (EF) is uncommon. Impaired EF may lead to occupational, personal, and social limitations, thus, a compromised quality of life. A comprehensive literature search was conducted through Scopus, Medline, and Cochrane Library using a pre-defined search strategy. Articles were selected after duplicate removal, initial screening, and full-text assessment. The demographic details, ioBM techniques, intraoperative tasks, and their assessments, the extent of resection (EOR), post-op EF and neurocognitive status, and feasibility and potential adverse effects of the procedure were reviewed. The correlations of tumor locations with intraoperative EF deficits were also assessed. A total of 13 studies with intraoperative EF assessment of 351 patients were reviewed. Awake-asleep-awake protocol was most commonly used. Most studies performed ioBM using bipolar stimulation, with a frequency of 60 Hz, pulse durations ranging 1-2 ms, and intensity ranging 2-6 mA. Cognitive function was monitored with the Stroop task, spatial-2-back test, line-bisection test, trail-making-task, and digit-span tests. All studies reported similar or better EOR in patients with ioBM for EF. When comparing the neuropsychological outcomes of patients with ioBM of EF to those without it, all studies reported significantly better EF preservation in ioBM groups. Most authors reported EF mapping as a feasible tool to obtain satisfactory outcomes. Adverse effects included intraoperative seizures which were easily controlled. AC with ioBM of EF is a safe, effective, and feasible technique that allows satisfactory EOR and improved neurocognitive outcomes with minimal adverse effects