Publications by authors named "Ahilan Kailaya-Vasan"

10 Publications

  • Page 1 of 1

Middle Frontal Gyrus and Area 55b: Perioperative Mapping and Language Outcomes.

Front Neurol 2021 10;12:646075. Epub 2021 Mar 10.

Department of Neurosurgery, King's College Hospital National Health Service Foundation Trust, London, United Kingdom.

The simplistic approaches to language circuits are continuously challenged by new findings in brain structure and connectivity. The posterior middle frontal gyrus and area 55b (pFMG/area55b), in particular, has gained a renewed interest in the overall language network. This is a retrospective single-center cohort study of patients who have undergone awake craniotomy for tumor resection. Navigated transcranial magnetic simulation (nTMS), tractography, and intraoperative findings were correlated with language outcomes. Sixty-five awake craniotomies were performed between 2012 and 2020, and 24 patients were included. nTMS elicited 42 positive responses, 76.2% in the inferior frontal gyrus (IFG), and hesitation was the most common error (71.4%). In the pMFG/area55b, there were seven positive errors (five hesitations and two phonemic errors). This area had the highest positive predictive value (43.0%), negative predictive value (98.3%), sensitivity (50.0%), and specificity (99.0%) among all the frontal gyri. Intraoperatively, there were 33 cortical positive responses-two (6.0%) in the superior frontal gyrus (SFG), 15 (45.5%) in the MFG, and 16 (48.5%) in the IFG. A total of 29 subcortical positive responses were elicited-21 in the deep IFG-MFG gyri and eight in the deep SFG-MFG gyri. The most common errors identified were speech arrest at the cortical level (20 responses-13 in the IFG and seven in the MFG) and anomia at the subcortical level (nine patients-eight in the deep IFG-MFG and one in the deep MFG-SFG). Moreover, 83.3% of patients had a transitory deterioration of language after surgery, mainly in the expressive component ( = 0.03). An increased number of gyri with intraoperative positive responses were related with better preoperative ( = 0.037) and worse postoperative ( = 0.029) outcomes. The involvement of the SFG-MFG subcortical area was related with worse language outcomes ( = 0.037). Positive nTMS mapping in the IFG was associated with a better preoperative language outcome ( = 0.017), relating to a better performance in the expressive component, while positive mapping in the MFG was related to a worse preoperative receptive component of language ( = 0.031). This case series suggests that the posterior middle frontal gyrus, including area 55b, is an important integration cortical hub for both dorsal and ventral streams of language.
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March 2021

Neurosurgery and coronavirus: impact and challenges-lessons learnt from the first wave of a global pandemic.

Acta Neurochir (Wien) 2021 02 21;163(2):317-329. Epub 2020 Nov 21.

Department of Neurosurgery, King's College Hospital, Denmark Hill, London, SE5 9RS, UK.

Introduction And Objectives: The novel severe acute respiratory syndrome coronavirus 2 (COVID-19) pandemic has had drastic effects on global healthcare with the UK amongst the countries most severely impacted. The aim of this study was to examine how COVID-19 challenged the neurosurgical delivery of care in a busy tertiary unit serving a socio-economically diverse population.

Methods: A prospective single-centre cohort study including all patients referred to the acute neurosurgical service or the subspecialty multidisciplinary teams (MDT) as well as all emergency and elective admissions during COVID-19 (18th March 2020-15th May 2020) compared to pre-COVID-19 (18th of January 2020-17th March 2020). Data on demographics, diagnosis, operation, and treatment recommendation/outcome were collected and analysed.

Results: Overall, there was a reduction in neurosurgical emergency referrals by 33.6% and operations by 55.6% during the course of COVID-19. There was a significant increase in the proportion of emergency operations performed during COVID-19 (75.2% of total, n=155) when compared to pre-COVID-19 (n = 198, 43.7% of total, p < 0.00001). In contrast to other published series, the 30-day perioperative mortality remained low (2.0%) with the majority of post-operative COVID-19-infected patients (n = 13) having underlying medical co-morbidities and/or suffering from post-operative complications.

Conclusion: The capacity to safely treat patients requiring urgent or emergency neurosurgical care was maintained at all times. Strategies adopted to enable this included proactively approaching the referrers to maintain lines of communications, incorporating modern technology to run clinics and MDTs, restructuring patient pathways/facilities, and initiating the delivery of NHS care within private sector hospitals. Through this multi-modal approach we were able to minimize service disruptions, the complications, and mortality.
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February 2021

White-matter commissures: a clinically focused anatomical review.

Surg Radiol Anat 2019 Jun 22;41(6):613-624. Epub 2019 May 22.

Anatomy Department, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.

Purpose: The objective of this review is to provide a structured approach to the main white matter commissures, their anatomic and radiological definition and disease implications.

Methods: The Pubmed database and The JAMA Network were used for the literature review and the following terms were searched using Sort by: Best Match and Sort by: Most Recent: telencephalic commissure, forebrain commissure anatomy, fornix anatomy, commissure of fornix, posterior commissure, corpus callosum, commissural agenesis, Probst bundle, corpus callosum disorders review, corpus callosum diseases review, Marchiafava-Bignami, Alzheimer's disease and Forel commissure; 36 papers were selected, one excluded due to the language barrier.

Results: The interhemispheric communication in the brain is achieved via the brain commissures, bundles of white matter linking the two cerebral hemispheres. Anterior white commissure (AWC)-related with olfactory and non-visual communication, hippocampal commissure-main efferent pathway of the hippocampus, connecting the hippocampal formation to structures beyond the temporal lobe, crucial in declarative memory formation and consolidation-and the corpus callosum (CC)-from the anterior commissure to the hippocampal commissure-are the main telencephalic commissures. Supramammilary commissure, posterior commissure, supraoptic commissure and habenular commissure are diencephalic commissures-unknown function, probably related to involuntary eye movements. Commissural agenesis (AWC is absent or impossible to recognize), Alzheimer's Disease (hippocampal commissure may contribute for disease dissemination) and agenesis of corpus callosum are some of the disturbances that involve the telenchephalic commissures.

Conclusions: A comprehensive understanding of the clinic-anatomic correlation is pivotal to understand the pathology and therefore improve our diagnostic accuracy and treatment options, in the background of all patient management.
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June 2019

Severe adverse radiation effects complicating radiosurgical treatment of brain arteriovenous malformations and the potential benefit of early surgical treatment.

J Clin Neurosci 2018 Sep 18;55:25-31. Epub 2018 Jul 18.

Department of Neurosurgery, King's College Hospital NHS Foundation Trust, London, UK; Institute of Psychiatry, King's College London, DeCrespigny Park, London, UK.

Treatment of brain arteriovenous malformations (AVM) with stereotactic radiosurgery is rarely complicated by severe adverse radiation effects (ARE). The treatment of these sequelae is varied and often ineffectual. We present three cases of brain AVMs treated with SRS, all complicated by severe AREs. All three cases failed to respond to what is currently considered the standard treatment - corticosteroids - and indeed one patient died as a result of the side effects of their extended use. Two cases were successfully treated with surgical excision of the necrotic lesion resulting in immediate clinical improvement. Having considered the experience described in this paper and reviewed the published literature to date we suggest that surgical treatment of AREs should be considered early in the management of this condition should steroid therapy not result in early improvement.
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September 2018

Clipping aneurysms improves outcomes for patients undergoing coiling.

J Neurosurg 2018 Jun 8:1-7. Epub 2018 Jun 8.

1Department of Neurosurgery, King's College Hospital NHS Foundation Trust, London, United Kingdom.

OBJECTIVEMost intracranial aneurysms are now treated by endovascular rather than by microsurgical procedures. There is evidence to demonstrate superior outcomes for patients with aneurysmal subarachnoid hemorrhage (aSAH) treated by endovascular techniques. However, some cases continue to require microsurgery. The authors have examined the relationship between the number of aneurysms treated by microsurgery and outcome for patients undergoing treatment for aSAH at neurosurgical centers in England.METHODSThe Neurosurgical National Audit Programme (NNAP) database was used to identify aSAH cases and to provide associated 30-day mortality rates for each of the 24 neurosurgical centers in England. Data were compared for association by regression analysis using the Pearson product-moment correlation coefficient and any associations were tested for statistical significance using the one-way ANOVA test. The NNAP data were validated utilizing a second, independent registry: the British Neurovascular Group's (BNVG) National Subarachnoid Haemorrhage Database.RESULTSIncreasing numbers of microsurgical cases in a center are associated with lower 30-day mortality rates for all patients treated for aSAH, irrespective of treatment modality (Pearson r = 0.42, p = 0.04), and for patients treated for aSAH by endovascular procedures (Pearson r = 0.42, p = 0.04). The correlations are stronger if all (elective and acute) microsurgical cases are compared with outcome. The BNVG data validated the NNAP data set for patients with aSAH.CONCLUSIONSThere is a statistically significant association between local microsurgical activity and center outcomes for patients with aSAH, even for patients treated endovascularly. The authors postulate that the number of microsurgical cases performed may be a surrogate indicator of closer neurosurgical involvement in the overall management of neurovascular patients and of optimal case selection.
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June 2018

Conus Medullaris Arteriovenous Malformation Presenting with Acute Dysphagia and Intractable Hiccups.

World Neurosurg 2018 Mar 2;111:261-263. Epub 2018 Jan 2.

Department of Neurosurgery, King's College Hospital, London, UK; Department of Neurosurgery, Clinical Hospital Dubrava, Zagreb, Croatia.

Background: Conus medullaris arteriovenous malformations (AVMs) are rare spinal vascular malformations presenting most frequently with features of myelopathy (Foix-Alajounine syndrome), radiculopathy, bowel/bladder dysfunction, or acute spinal hemorrhage (Coup de poignard of Michon) causing profound neurological deficit. Here we present the case of a young patient with progressive dysphagia and intractable hiccups as a rare first presentation symptom of later verified conus medullaris AVM.

Case Description: A 21-year-old male patient presented with acute onset of dysphagia and persistent hiccups. His magnetic resonance imaging of the spine demonstrated a lesion at the T11 and T12 levels with an associated holocord syrinx and syringobulbia to the level of the medulla. The patient underwent a decompressive suboccipital craniectomy and C1 (atlas) laminectomy with wide myelotomy of the medulla followed by T11 and T12 laminectomy and AVM reduction. Two days after partial AVM occlusion the patient developed transient worsening of his symptoms. Repeat magnetic resonance imaging showed recurrence of dilatation of the central canal. A syringo-subarachnoid shunt was sited at the level of the previous myelotomy of the medulla, after which his neurological symptoms resolved completely.

Conclusions: This is the first case report in the English literature to date of a conus AVM presenting with intractable hiccups. These are extremely rare sporadic vascular malformations, and although their natural history is poorly understood, symptomatic patients generally deteriorate, culminating in severe disability. Management requires a multimodality approach including combined endovascular and microsurgical treatment. The patient in our case made a full recovery confirmed at 2-year follow-up.
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March 2018

Intracerebral Masson's Tumor-Slow-Filling Vascular Lesion Demonstrated by Indocyanine Green Video Angiography.

World Neurosurg 2017 May 25;101:812.e15-812.e19. Epub 2017 Mar 25.

Department of Neurosurgery, Royal Hallamshire Hospital, Sheffield, United Kingdom.

Background: Intravascular papillary endothelial hyperplasia, or Masson's tumors, are benign vascular lesions that are rarely seen intracranially. The vascular characteristics of these lesions are also unknown.

Case Description: We report the case of a 24-year-old male patient with a 3-year history of headache and dizziness. Neuroradiologic imaging showed a slow-growing lesion consistent with a low-grade glioma. Intraoperative appearance was of a vascular lesion that was slow filling as demonstrated with indocyanine green video angiography. Histologic analysis following resection revealed intravascular papillary endothelial hyperplasia (Masson's tumor).

Conclusion: Masson's tumors are slow-filling vascular lesions. The preoperative diagnosis of this lesion is difficult as it can mimic a neoplastic lesion. Conservative and surgical treatment options should therefore be carefully considered. Patients with subtotal resection must undergo long-term follow-up surveillance imaging as recurrence is a possibility.
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May 2017

Proposal for a prospective multi-centre audit of chronic subdural haematoma management in the United Kingdom and Ireland.

Br J Neurosurg 2014 Apr 23;28(2):199-203. Epub 2013 Sep 23.

Department of Neurosurgery, James Cook University Hospital , Middlesbrough , UK.

BACKGROUND. Chronic subdural haematoma (CSDH) is a common condition that increases in incidence with rising age. Evacuation of a CSDH is one of the commonest neurosurgical procedures; however the optimal peri-operative management, surgical technique, post-operative care and the role of adjuvant therapies remain controversial. AIM. We propose a prospective multi-centre audit in order to establish current practices, outcomes and national benchmarks for future studies. METHODS. Neurosurgical units (NSU) in the United Kingdom and Ireland will be invited to enrol patients to this audit. All adult patients aged 16 years and over with a primary or recurrent CSDH will be eligible for inclusion. OUTCOME MEASURES AND ANALYSIS. The proposed outcome measures are (1) clinical recurrence requiring re-operation within 60 days; (2) modified Rankin scale (mRS) score at discharge from NSU; (3) morbidity and mortality in the NSU; (4) destination at discharge from NSU and (5) length of stay in the NSU. Audit standards have been derived from published systematic reviews and a recent randomised trial. The proposed standards are clinical recurrence rate < 20%; unfavourable mRS (4-6) at discharge from NSU < 30%; mortality rate in NSU < 5%; morbidity rate in NSU < 10%. Data will be submitted directly into a secure online database and analysed by the study's management group. CONCLUSIONS. The audit will determine the contemporary management and outcomes of patients with CSDH in the United Kingdom and Ireland. It will inform national guidelines, clinical practice and future studies in order to improve the outcome of patients with CSDH.
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April 2014

Functional and clinical outcomes following surgical treatment in patients with cervical spondylotic myelopathy: a prospective study of 81 cases.

J Neurosurg Spine 2011 Mar 14;14(3):348-55. Epub 2011 Jan 14.

Division of Genetics and Development, Toronto Western Research Institute, Ontario, Canada.

Object: Cervical spondylotic myelopathy (CSM) is the most common cause of spinal dysfunction in the elderly. Operative management is beneficial for most patients with moderate/severe myelopathy. This study examines the potential confounding effects of age, sex, duration of symptoms, and comorbidities on the functional outcomes and postoperative complications in patients who underwent cervical decompressive surgery.

Methods: We included consecutive patients who underwent surgery from December 2005 to October 2007. Functional outcomes were assessed using the Nurick grading system and the modified Japanese Orthopaedic Association and Berg Balance scales. Comorbidity indices included the Charlson Comorbidity Index and the number of ICD-9 codes.

Results: There were 57 men and 24 women with a mean age of 57 years (range 32-88 years). The mean duration of symptoms was 25.2 months (range 1-120 months). There was a significant functional recovery from baseline to 6 months after surgery (p < 0.01). Postoperative complications occurred in 18.5% of cases. Although the occurrence of complications was not significantly associated with sex (p = 0.188), number of ICD-9 codes (p = 0.113), duration of symptoms (p = 0.309), surgical approach (p = 0.248), or number of spine levels treated (p = 0.454), logistic regression analysis showed that patients who developed complications were significantly older than patients who had no complications (p = 0.018). Only older age (p < 0.002) and greater number of ICD-9 codes (p < 0.01) were significantly associated with poorer functional recovery after surgical treatment. However, none of the studied factors were significantly associated with clinically relevant functional recovery after surgical treatment for CSM (p > 0.05).

Conclusions: Our results indicate that surgery for CSM is associated with significant functional recovery, which appears to reach a plateau at 6 months after surgery. Age is a potential predictor of complications after decompressive surgery for CSM. Whereas older patients with a greater number of preexisting medical comorbidities had less favorable functional outcomes after surgery for CSM in the multivariate regression analysis, none of the studied factors were associated with clinically relevant functional recovery after surgery in the logistic regression analysis. Therefore, age-matched protocols based on preexisting medical comorbidities may reduce the risk for postoperative complications and improve functional outcomes after surgical treatment for CSM.
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March 2011

A novel approach to quantitatively assess posttraumatic cervical spinal canal compromise and spinal cord compression: a multicenter responsiveness study.

Spine (Phila Pa 1976) 2011 May;36(10):784-93

Division of Genetics and Development, Toronto Western Research Institute, University Health Network, Toronto, Canada.

Study Design: Multicenter retrospective study.

Objective: To examine whether posttraumatic cervical spinal canal compromise and spinal cord compression are responsive to changes in motor and sensory functions.

Summary Of Background Data: The maximum canal compromise (MCC) and maximum spinal cord compression (MSCC) were developed to quantitatively assess canal stenosis and spinal cord compression using computed tomographic (CT) scan and magnetic resonance imaging (MRI) in the setting of acute spine trauma.

Methods: We included 100 consecutive patients with acute spine trauma. Patients were classified into three groups as follows: patients with acute spine trauma without spinal cord injury (group 1), patients with incomplete spinal cord injury (group 2), and patients with complete spinal cord injury (group 3). We studied three quantitative imaging parameters given as follows: MCC using CT-based measurements, MCC using T1-MRI based measurements, and MSCC using T2-MRI based measurements.

Results: There were 78 male patients and 22 female patients with ages from 17 to 82 years (mean age = 45 years). In group 1, there were no significant differences regarding the mean MRI-MCC and MSCC among the spine levels. Although most spine levels were statistically comparable regarding the CT-MCC in patients of group 1, the C7 level significantly differed from the C3 level. Comparisons among all three patient groups showed significant differences regarding the mean MRI-MCC and MSCC, but no significant differences were observed in the mean CT-MCC between groups 1 and 2, and between groups 1 and 3. Data analyses using operating characteristics of each radiologic parameter indicated that only the MRI parameters had consistently optimal cutoff points to distinguish between groups 1 and 2, and between groups 2 and 3.

Conclusion: Our results suggest that the MRI-based measurements of canal compromise and spinal cord compression are responsive to changes in motor and sensory functions. However, the MCC using CT-based measurements provides inconsistent results that can result in misdiagnosis in the clinical setting.
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May 2011