Keyoumars Ashkan

Keyoumars Ashkan
King's College Hospital NHS Foundation Trust · Department of Neurosurgery

Professor

About

457
Publications
62,797
Reads
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9,078
Citations
Citations since 2017
247 Research Items
5833 Citations
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201720182019202020212022202302004006008001,0001,200
201720182019202020212022202302004006008001,0001,200

Publications

Publications (457)
Article
Full-text available
Subependymal Giant Cell Astrocytoma (SEGA) is a common diagnosis in patients with Tuberous Sclerosis. Although surgical treatment is often required, resection may entail a significant risk for cognitive function given the anatomical relation with critical structures such as the fornices and subgenual area. Therefore, target subtotal resections usin...
Article
Full-text available
Parkinson’s disease (PD) is a complex neurodegenerative disorder, leading to impairment of various neurological faculties, including motor, planning, cognitivity, and executive functions. Motor- and non-motor symptoms of the disease may intensify a patient’s restrictions to performing usual tasks of daily living, including driving. Deep Brain Stimu...
Preprint
Full-text available
Subthalamic nucleus (STN) beta-triggered adaptive deep brain stimulation (ADBS) has been shown to provide clinical improvement comparable to conventional continuous DBS (CDBS) in people with Parkinson's disease (PD) with less energy delivered to the brain and less stimulation induced side-effects. However, several questions remain unanswered. First...
Article
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To optimally adjust our behavior to changing environments we need to both adjust the speed of our decisions and movements. Yet little is known about the extent to which these processes are controlled by common or separate mechanisms. Furthermore, while previous evidence from computational models and empirical studies suggests that the basal ganglia...
Article
Full-text available
Unlike sleep-walkers, patients with rapid-eye-movement-behaviour disorder (RBD) rarely leave the bed during the re-enactment of their dreams. RBD movements may be independent of spatial co-ordinates of the ‘outside-world’, and instead rely on (allocentric) brain-generated virtual space-maps, as evident by patients’ limited truncal/axial movements....
Article
Objectives The study aims to review therapeutic strategies in the management of craniospinal tumours in pregnant patients and the factors that may influence the management along with their influence on maternal & foetal outcomes. Materials and Methods A retrospective single-centre cohort study was performed at a tertiary neurosurgical referral c...
Article
Full-text available
BACKGROUND: Awake craniotomy (AC) enables real-time monitoring of cortical and subcortical functions when lesions are in eloquent brain areas. AC patients are exposed to various preoperative, intraoperative, and postoperative stressors, which might affect their mental health. OBJECTIVE: To conduct a systematic review to better understand stress, a...
Article
Importance Glioblastoma is the most lethal primary brain cancer. Clinical outcomes for glioblastoma remain poor, and new treatments are needed. Objective To investigate whether adding autologous tumor lysate-loaded dendritic cell vaccine (DCVax-L) to standard of care (SOC) extends survival among patients with glioblastoma. Design, Setting, and Pa...
Article
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Introduction Surgery remains the mainstay for treatment of primary glioblastoma, followed by radiotherapy and chemotherapy. Current standard of care during surgery involves the intraoperative use of image-guidance and 5-aminolevulinic acid (5-ALA). There are multiple other surgical adjuncts available to the neuro-oncology surgeon. However, access t...
Article
BACKGROUND Standard of care (SOC) and patient survival in glioblastoma have changed little in the past 17 years. We evaluated in a phase 3 trial whether adding an autologous tumor lysate-loaded dendritic cell vaccine (murcidencel) to SOC extends survival. Patients and METHODS Newly diagnosed glioblastoma patients were randomized 2:1 to either murc...
Article
Objectives In adults with dystonia Probabilistic Stimulation Mapping (PSM) has identified putative “sweet spots” for stimulation. We aimed to apply PSM to a cohort of Children and Young People (CYP) following DBS surgery. Methods Pre-operative MRI and post-operative CT images were co-registered for 52 CYP undergoing bilateral pallidal DBS (n = 31...
Article
Introduction Colloid cysts, although benign, may occasionally cause obstructive hydrocephalus and sudden death. Reliable prognostic factors for symptomatic progression have been sought with heterogenous results. Methods We conducted a retrospective review of all cases of colloid cysts of the third ventricle managed at our centre between 2009 and 2...
Article
AIMS To describe the methods used to assess and monitor motor function during awake craniotomy surgery for tumour resection. METHOD A service review was carried out over 10 months. Patients with highly motor eloquent lesions – invasion of primary motor cortex or fronto-parietal connections involved in motor cognition – were included. Clinical note...
Article
AIMS 5-ALA (Gliolan©) is a valuable surgical tool used predominantly in high grade tumours, which utilises tissue fluorescence to improve the visualisation of the brain-tumour interface. This ensures safe maximal resection, while preserving healthy brain. While Gliolan© use in low grade tumours has previously been reported with variable results, re...
Article
AIMS There is a gap in supporting patients with sexual relationships and intimacy. The aim of this study is to establish if patients with a brain tumour feel they are able to ask questions and concerns about sex, relationships and intimacy following diagnosis; is there an unmet need and how can this be addressed. METHOD An anonymous survey was sen...
Article
AIMS Assess the impact of tubular retractor-assisted transsulcal minimal invasive parafascicular approaches(tsMIPS) in the cortical vascularization using indocianin green angiography(ICGA) during removal of deep-seated cerebral tumours. METHOD Single-centre prospective cohort study of patients with deep-seated lesions – distance to nearest sulcus...
Article
AIMS Butterfly glioblastomas (bGBM) are a rare subset of WHO grade IV tumours, that carry a poor prognosis with a median survival ranging between 3 to 6 months. Our study aims to add to the literature on how these tumours should be best managed when presenting to a neurosurgical unit. METHOD We performed a retrospective analysis from January 2009...
Article
Full-text available
Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a dual-...
Article
Background: Transsulcal minimally invasive parafasicular (TsMIP) approaches to brain tumor resection use tubular retractors to minimize iatrogenic brain injury. Dynamic cortical and subcortical continuous neurophysiological mapping facilitates safer resection of motor-eloquent tumors. Objective: To describe a new technique to address the challen...
Preprint
Full-text available
A bstract Periodic features of neural time series data, such as local field potentials (LFP), are often quantified using power spectra. While the aperiodic exponent of spectra is typically disregarded, it is nevertheless modulated in a physiologically-relevant manner and was recently hypothesised to reflect excitation/inhibition (E/I) balance in ne...
Preprint
Full-text available
Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a du...
Article
Full-text available
Objectives: We aim to demonstrate intraoperative recording of cerebellar to cortical pathways that have not been previously recorded in humans, though imaged. Methods: We report two cases with intraoperative neurophysiological mapping of cerebello-cortical tracts. Direct electrical stimulation of subcortical cerebellum along with recordings of c...
Poster
Full-text available
Description of methods and outcomes for awake craniotomy for motor eloquent intrinsic tumours in our practice.
Article
Objective To report imaging protocol and scheduling variance in routine care of glioblastoma patients in order to demonstrate challenges of integrating deep learning models in glioblastoma care pathways. Additionally, to understand the most common imaging studies and image contrasts to inform the development of potentially robust deep learning mode...
Article
Full-text available
Identifying white matter (WM) tracts to locate eloquent areas for preoperative surgical planning is a challenging task. Manual WM tract annotations are often used but they are time-consuming, suffer from inter- and intra-rater variability, and noise intrinsic to diffusion MRI may make manual interpretation difficult. As a result, in clinical practi...
Article
Background: Intraoperative neuromonitoring of motor functions experienced a dramatical revolution in the last years thanks to significant advances in anesthesiology procedures and both preoperative and intraoperative mapping techniques. Asleep, awake, and combined intraoperative mapping techniques were responsible for an improvement in the functio...
Article
Full-text available
Previous studies have shown less access to deep brain stimulation (DBS) for Parkinson's disease (PD) in women compared to men raising concerns about a potential gender gap resulting from nonclinical factors or gender differences in clinical efficacy for postoperative quality of life (QoL), motor, and nonmotor symptoms (NMS) outcomes. This was a cro...
Poster
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Aim • To assess the possibility of a dual strip method to obtain direct cortical stimulation for continuous real-time cortical monitoring and subcortical mapping of motor and visual pathways simultaneously Methods • Prospective single-centre study • Parietal lobe lesions resected with dual subdural strip electrodes for cortical subcortical mapping...
Poster
Full-text available
Does processed EEG (Entropy) correlate with IOM measures: scalp corkscrew EEG and direct cortical electrode ECoG in awake craniotomy for intrinsic tumour?
Article
Background: The benefits of using 5-aminolevulinic acid (5-ALA) in resection of grade IV tumors have been extensively researched. However, few studies have investigated the use of 5-ALA in grade III gliomas. Objective: To discover whether 5-ALA provides significant benefit in assisting resection of grade III gliomas. Methods: A single-center,...
Article
Full-text available
Over the last two decades deep brain stimulation (DBS) has become a widely used therapeutic alternative for a variety of neurological and psychiatric diseases. The extensive experience in the field of movement disorders has provided valuable knowledge and has led the path to its application to other hard-to-treat conditions. Despite the recognised...
Article
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Objective Monitoring biomarkers using machine learning (ML) may determine glioblastoma treatment response. We systematically reviewed quality and performance accuracy of recently published studies. Methods Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis: Diagnostic Test Accuracy, we extracted articles from MEDLINE, EMB...
Article
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Deep-seated brain tumours represent a unique neurosurgical challenge as they are often surrounded by eloquent structures. We describe a minimally invasive technique using tubular retractors and intraoperative neurophysiology monitoring for open biopsy of a deep-seated lesion surrounded by the corticospinal tract. We used preoperative functional map...
Chapter
Full-text available
Neurosurgery has provided an alternative option for patients with refractory psychiatric indications. Lesion procedures were the initial techniques used, but deep brain stimulation (DBS) has the advantage of relative reversibility and adjustability. This chapter sets out to delineate the current evidence for DBS use in paediatric psychiatric condit...
Article
Sneezing is a poorly understood, protective reflex response. It’s characterized by the following sequence: eye closure, inspiration, glottic closure, forced expiration with sudden glottic opening, and release of an elevated intrathoracic pressure creating a flow of explosive air through the nose.¹ Studies have indicated an anatomic sneezing area of...
Article
Full-text available
To the Editor: We read with great enthusiasm the article published by Khalafallah et al.1 The authors address an utmost point of importance in contemporary glioma surgery: an operational definition for supratotal resection (SpTR) in glioblastoma (GBM). We believe this is a potential landmark article on this subject because it paves the way toward...
Preprint
Full-text available
Objectives: The study aims to evaluate therapeutic strategies in the management of craniospinal tumours in pregnant patients and the factors that influence the management along with their influence on maternal & foetal outcomes. Materials and Methods: A retrospective single-centre cohort study was performed at a tertiary neurosurgical referral ce...
Article
Full-text available
To identify predictors of 36-month follow-up quality of life (QoL) outcome after bilateral subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson’s disease (PD). In this ongoing, prospective, multicenter international study (Cologne, Manchester, London) including 73 patients undergoing STN-DBS, we assessed the following scales preoperati...
Article
Background: The satisfaction with life and, in particular, with treatment in Parkinson's disease (PD) is understudied. Objective: To explore a new 7-item rating tool assessing satisfaction with life and treatment (SLTS-7) in PD. Methods: In this cross-sectional, multi-center study, including patients screened for advanced therapies, psychometr...
Preprint
Full-text available
Intraoperative neuromonitoring of motor functions experienced a dramatical revolution in the last years due to significant advances in anaesthesiology procedures and both preoperative and intraoperative mapping techniques. Asleep, awake and combined intraoperative mapping techniques were responsible for an improvement in the functional outcomes in...
Article
Full-text available
Background Central itch syndrome has been previously described in conditions such as stroke. The neurophysiology of central itch syndrome has been investigated in non-human primates but remains incompletely understood. Methods We report an observational study of a rare case of severe central itch following thalamic deep brain stimulation and postu...
Article
Aims Primary central nervous system lymphoma (PCNSL) is a rare form of non–Hodgkin lymphoma with exclusive manifestations in the central nervous system, leptomeninges and eyes. It forms around 5% of all primary brain tumours. It is an aggressive tumour which has a poor prognosis if left untreated. It is imperative that diagnosis is made timely so t...
Conference Paper
Aims Extent of resection is associated with better survival in patients with glioblastoma. Numerous surgical adjuncts can be used to achieve maximal safe resection - including fluorescence-guidance with 5-aminolevulinic acid (5-ALA), neuronavigation, intraoperative ultrasound (IoUS), intra-operative MRI (iMRI), tractography, electrophysiological mo...
Article
Aims Signs and symptoms that develop in people with brain tumours are often attributed to their tumour. The prevalence and management of functional neurological symptoms in brain tumour patients have received little attention. This is surprising because functional neurological symptoms complicate management greatly and misdiagnosis can lead to inap...
Article
Full-text available
Surgery for meningiomas involving dural venous sinuses is challenging. We describe a case of a peritorcular meningioma involving major venous sinuses, which was removed using a venous sparing approach with the aid of intraoperative ultrasound. We found ultrasound to be a useful adjunct as it enabled us to get real-time information about the locatio...
Article
BACKGROUND The aim of the systematic review was to assess recently published studies on diagnostic test accuracy of glioblastoma treatment response monitoring biomarkers in adults, developed through machine learning (ML). MATERIAL AND METHODS PRISMA methodology was followed. Articles published 09/2018-01/2021 (since previous reviews) were searched...
Article
Full-text available
Device-aided therapies, including levodopa-carbidopa intestinal gel infusion, apomorphine subcutaneous infusion, and deep brain stimulation, are available in many countries for the management of the advanced stage of Parkinson’s disease (PD). Currently, selection of device-aided therapies is mainly focused on patients’ motor profile while non-motor...
Article
Full-text available
Background Fatigue is a common and disabling non-motor symptom (NMS) in Parkinson’s disease (PD) patients. However, the effect of subthalamic nucleus (STN) deep brain stimulation (DBS) on fatigue has not been widely studied. Objective To determine the effect of STN DBS on fatigue in PD patients, measured by the Non-motor symptoms scale (NMSS). Me...
Article
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Local fiber orientation distributions (FODs) can be computed from diffusion magnetic resonance imaging (dMRI). The accuracy and ability of FODs to resolve complex fiber configurations benefits from acquisition protocols that sample a high number of gradient directions, a high maximum b-value, and multiple b-values. However, acquisition time and sca...
Article
Full-text available
Ki67 is a marker for proliferation of a given cell population. Low expression of Ki67 may be associated with a favourable outcome. We investigate how the proliferation index correlates with the location, morphology and behaviour of WHO grade II ependymomas with a single-centre cohort study of adult patients admitted for surgery of WHO grade II epen...
Article
Functional neurosurgery involves the surgical management of a wide range of neurological diseases with the aim of treating conditions such as movement disorders, spasticity, epilepsy and intractable pain. Functional neurosurgery began with ablative surgical techniques involving destruction of neural structures responsible for the aberrant neural pa...
Article
Background and importance Insertion of ventricular catheters into small ventricles may require image guidance. Several options exist, including ultrasound guidance, frameless, and frame-based stereotactic approaches. There is no literature on management options when conventional image guidance fails to cannulate the ventricle. The accuracy of the r...
Article
Full-text available
Background Glioblastoma (GBM) is the commonest primary malignant brain tumour in adults and effective treatment options are limited. Combining local chemotherapy with enhanced surgical resection using 5-aminolevulinic acid (5-ALA) could improve outcomes. Here we assess the safety and feasibility of combining BCNU wafers with 5-ALA-guided surgery. M...
Article
Full-text available
Introduction: DBS is a widely used therapy for PD. There is now a choice between fixed-life implantable pulse generators (IPGs) and rechargeable IPGs, each having advantages and disadvantages. This study aimed to evaluate the preference and satisfaction of Chinese patients with Parkinson's disease (PD) who were treated with deep brain stimulation (...
Article
Full-text available
Penfield's motor homunculus describes a caricaturised yet useful representation of the map of various body parts on the pre-central cortex. We propose a supplemental map of the clinically represented areas of human body in pre-central cortex and a novel subcortical corticospinal tract map. We believe this knowledge is essential for safe surgery in...
Article
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IntroductionDystonic opisthotonus is defined as a backward arching of the neck and trunk, which ranges in severity from mild backward jerks to life-threatening prolonged severe muscular spasms. It can be associated with generalized dystonic syndromes or, rarely, present as a form of axial truncal dystonia. The etiologies vary from idiopathic, genet...
Article
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To the Editor: Keeble et al from our institution recently reported on the reliability and feasibility of combining electromagnetic (EM) neuronavigation systems and intraoperative neuromonitoring (IONM). Strategies to minimize the electrical interference from the EM navigation system to allow accurate recording of intra- operative somatosensory evok...
Article
Full-text available
Background: Deep brain stimulation (DBS) is an established treatment for hyperkinetic movement disorders. Patients undergoing DBS can choose between the use of a rechargeable or non-rechargeable battery for implanted pulse generators (IPG). Objectives: In this study, we aimed to evaluate patient preferences and satisfaction with rechargeable and no...
Conference Paper
Full-text available
Objective: The study analyzes the monitoring and subcortical mapping techniques for intra-axial visual eloquent tumors and their impact in the visual outcome. Design: It is a single-center prospective study from 2018- 2020. Subjects: Patients with intra-axial visual eloquent tumors(n=34) were included in the study. Methods: Single-center prospec...
Poster
Full-text available
Objectives: The study aims to evaluate craniospinal tumours in pregnant patients and the therapeutic strategies that influence maternal and foetal outcomes along with the challenges faced in management Design: A retrospective single-centre cohort study was performed at a tertiary neurosurgical referral centre. Subjects: Pregnant patients referre...
Poster
Full-text available
Abstract Objective: We summarise our experience and challenges faced with the non-navigated intraoperative ultrasound in cranial neuro-oncological surgery at a tertiary neurosurgical centre in UK. Design: It is a retrospective single-centre cohort study for a period of 2 years between Dec 2017-Dec 2019. Subjects: Adult patients(n=90) referred t...
Poster
Full-text available
Abstract Objective: The study aims to propose a supplemental map of the clinically represented areas of human body in pre-central cortex and a novel subcortical corticospinal tract map that are accurate and essential for safe surgery in patients with eloquent brain lesions. Design: It is a 5-year single-centre retrospective cohort study between 2...
Preprint
Full-text available
The aim of the systematic review was to assess recently published studies on diagnostic test accuracy of glioblastoma treatment response monitoring biomarkers in adults, developed through machine learning (ML). Articles were searched for using MEDLINE, EMBASE, and the Cochrane Register. Included study participants were adult patients with high grad...
Poster
Full-text available
We have recently introduced a full sized operative table beanbag surgical positioner (Vacuform 2.0©) to our operating theatres. • The operative beanbag is able to be positioned while soft, mould to the patients position and then solidify with vacuum suction. • Benefits include: speed, avoiding pressure complications, achieving maximal surgical acce...
Article
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Introduction Europe was the epicentre of the COVID-19 pandemic in March 2020, with the highest number of cases and deaths between March and April. In May, the infection numbers registered a fall followed by a second new rise, not proportionally reflected by an increase in the number of deaths. We aimed to investigate the relationship between diseas...