Publications by authors named "Aristotelis Kalyvas"

Brain metastases (BMs) are the most common intracranial tumors in adults. Their heterogeneity, potential multifocality, and complex biomolecular behavior pose significant diagnostic and therapeutic challenges. Artificial intelligence (AI) has the potential to revolutionize BM diagnosis by facilitating early lesion detection, precise imaging segmentation, and non-invasive molecular characterization.

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This study investigated Theory of Mind (ToM) deficits in patients with suspected idiopathic normal pressure hydrocephalus (iNPH), a condition affecting motor, cognitive and autonomic functions. Given the overlap between ToM-related neural networks and those affected in iNPH, we examined whether ToM impairments are a feature of the disease. Thirty-eight patients with possible/probable iNPH and 25 healthy controls completed the Reading the Mind in the Eyes Test (RMET) along with typically administered neuropsychological tests in this population.

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Background: Brain metastases (BrM) from prostate cancer (PC) are rare. This study sought to evaluate their prevalence, clinical features, treatment modalities, and survival outcomes.

Methods: From a database of BrM patients, we analyzed 28 cases of prostate cancer treated at our center between 2008 and 2023.

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Glioblastomas (GBMs) constitute the most common malignant tumors of the Central Nervous System (CNS) with a complex molecular, genetic and histological profile and extensive heterogenicity. GBMs are notoriously difficult to treat, with morbidity and mortality rate that remain high and practically unchanged, despite the aggressive and multimodal treatment strategies. Keeping up with current research and emerging scientific data is of primary importance for the detection of new molecular targets, enabling the design of novel therapeutic strategies.

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Background And Objectives: Previous reports have suggested that neoadjuvant stereotactic radiosurgery (SRS) for brain metastases (BrMets) mitigates the elevated risks of radiation necrosis (RN) and meningeal recurrence associated with adjuvant SRS. We report treatment outcomes from a multicenter phase II trial (NCT03368625) of single-fraction neoadjuvant SRS for large BrMets.

Methods: Patients with 1 index BrMet requiring resection and up to 9 nonindex BrMets not requiring resection were recruited across 3 centers and treated with single-fraction SRS (14-21 Gy) targeting the index lesion with a 2-mm margin, followed by surgical resection.

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The somato-cognitive action network (SCAN) consists of three nodes interspersed within Penfield's motor effector regions. The configuration of the somato-cognitive action network nodes resembles the one of the 'plis de passage' of the central sulcus: small gyri bridging the precentral and postcentral gyri. Thus, we hypothesize that these may provide a structural substrate of the somato-cognitive action network.

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Objectives: The primary objective of this prospective review was to compare quality of life between patients undergoing endoscopic and open skull base approaches.

Study Type And Design: Prospective Review.

Methods: Five centers recruited consecutive patients treated surgically for skull base neoplasms between 2012 to 2018.

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Background/aim: Brain arteriovenous malformations (AVMs) are vascular malformations characterized by dysmorphic, aberrant vasculature. During previous surgeries of compact nidus brain AVMs (representing the majority of cases), we have observed a "shiny" plane between nidal and perinidal AVM vessels and the surrounding grey and white matter and hypothesized that preoperative neuroimaging of brain AVMs may show a neuroradiological correlate of these intraoperative observations.

Patients And Methods: We retrospectively reviewed and analyzed multiplanar and multisequence 3-Tesla magnetic resonance (3T MR) imaging in five consecutive brain AVMs with special attention on imaging characteristics of the brain-AVM interface, i.

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Background/objectives: Around 20% of cancer patients will develop brain metastases (BrMs), with 15-25% occurring in the posterior fossa (PF). Although the effectiveness of systemic therapies is increasing, surgery followed by stereotactic radiosurgery (S+SRS) versus definitive SRS remains the mainstay of treatment. Given the space restrictions within the PF, patients with BrMs in this location are at higher risk of brainstem compression, hydrocephalus, herniation, coma, and death.

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Purpose: Pituitary neuroendocrine tumors (pitNETs) are benign tumors that may recur after surgical resection or persist following medical management. The objective of this study was to evaluate outcomes and toxicities of patients with pitNETs treated with stereotactic radiosurgery (SRS) at a single institution.

Methods: We completed a retrospective, single-institution study of patients with pitNETs treated with frame-based, single-fraction, cobalt-60 SRS between September 2005 and June 2023.

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Article Synopsis
  • The study explores how the volume of cerebrospinal fluid (CSF) removed during the Lumbar Tap Test (LTT) affects gait improvement in patients with idiopathic normal pressure hydrocephalus (iNPH).
  • Seventy-six iNPH patients were analyzed, with results showing that larger volumes of CSF removed (greater than 40 ml) correlate with significantly better improvements in walking ability.
  • Additionally, patients with more severe initial gait issues showed greater improvement regardless of the CSF volume removed, emphasizing the impact of initial condition on recovery.
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Article Synopsis
  • * This study utilized advanced techniques on samples from 1065 humans and 41 rhesus macaques to explore these connections, revealing a link between the posterior precuneus (POS2) and the temporal pole areas through the cingulum.
  • * Findings enhance our understanding of brain connectivity and could help integrate anatomical knowledge with functional roles in both healthy and diseased brains.
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Article Synopsis
  • Deep Brain Stimulation (DBS) effectively improves symptoms of Parkinson's disease, including tremor, bradykinesia, rigidity, and axial symptoms, by stimulating specific white matter tracts.
  • A study involving 237 patients identified distinct brain tracts linked to improvements in each symptom, with tremor associated with the primary motor cortex and cerebellum, and axial symptoms linked to the supplementary motor cortex and brainstem.
  • An introduced algorithm utilizes these symptom-tract connections to tailor DBS settings for individual patients, aiming to enhance treatment effectiveness based on the most impactful symptoms for each person.
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Comprehensive understanding of the neural circuits involving the ventral tegmental area is essential for elucidating the anatomofunctional mechanisms governing human behaviour, in addition to the therapeutic and adverse effects of deep brain stimulation for neuropsychiatric diseases. Although the ventral tegmental area has been targeted successfully with deep brain stimulation for different neuropsychiatric diseases, the axonal connectivity of the region is not fully understood. Here, using fibre microdissections in human cadaveric hemispheres, population-based high-definition fibre tractography and previously reported deep brain stimulation hotspots, we find that the ventral tegmental area participates in an intricate network involving the serotonergic pontine nuclei, basal ganglia, limbic system, basal forebrain and prefrontal cortex, which is implicated in the treatment of obsessive-compulsive disorder, major depressive disorder, Alzheimer's disease, cluster headaches and aggressive behaviours.

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Background: With modern treatment paradigms, olfactory neuroblastoma (ONB) has favorable overall survival (OS); however, the incidence of recurrence remains high. The primary aims of this study were to delineate the prognosis of recurrence of ONB and explore how recurrence subsites are associated with OS, disease-specific survival (DSS), and further recurrence.

Methods: A retrospective chart review of ONB cases from nine academic centers between 2005 and 2021 was completed.

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Objective: The lateral retrocanthal transorbital endoscopic approach (LRCTEA) facilitates trajectory to the middle fossa, preserving the lateral canthal tendon and thus avoiding postoperative complications such as eyelid malposition. Here, the authors sought to define the surgical anatomy and technique of LRCTEA using a stepwise approach in cadaveric heads and offer an in-depth examination of existing quantitative data from cadaveric studies.

Methods: The authors performed LRCTEA to the middle cranial fossa under neuronavigation in 7 cadaveric head specimens that underwent high-resolution (1-mm) CT scans preceding the dissections.

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Introduction: The connectivity of the temporoparietal (TP) region has been the subject of multiple anatomical and functional studies. Its role in high cognitive functions has been primarily correlated with long association fiber connections. As a major sensory integration hub, coactivation of areas within the TP requires a stream of short association fibers running between its subregions.

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Background: Stereotactic radiosurgery (SRS) has supplanted whole brain radiotherapy (WBRT) as standard-of-care adjuvant treatment following surgery for brain metastasis (BrM). Concomitant with the adoption of adjuvant SRS, a new pattern of failure termed "Pachymeningeal failure" (PMF) has emerged.

Methods: We reviewed a prospective registry of 264 BrM patients; 145 and 119 were treated adjuvantly with WBRT and SRS, respectively.

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Background: Aim of the present study is to investigate whether preoperative neurocognitive status is prognostically associated with overall survival (OS) in newly diagnosed glioblastoma (GBM) patients.

Methods: Ninety patients with dominant-hemisphere IDH-wild-type GBM were assessed by Mini Mental Status Exam (MMSE), Trail Making Test (TMT) A and B parts, and Control Word Association Test (COWAT) phonemic and semantic subtests. Demographics, Karnofsky Performance Scale, tumor parameters, type of surgery, and adjuvant therapy data were available for patients.

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The model of the four streams of the prefrontal cortex proposes 4 streams of information: motor through Brodmann area (BA) 8, emotion through BA 9, memory through BA 10, and emotional-related sensory through BA 11. Although there is a surge of functional data supporting these 4 streams within the PFC, the structural connectivity underlying these neural networks has not been fully clarified. Here we perform population-based high-definition tractography using an averaged template generated from data of 1,065 human healthy subjects acquired from the Human Connectome Project to further elucidate the structural organization of these regions.

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Only a limited number of studies have focused on the results of the Endoscopic Endonasal Approach (EEA) for treatment of prolactinomas. We sought to assess the effectiveness of EEA for prolactinoma surgery, identify factors for disease remission, and present our approach for the management of persistent disease. Forty-seven prolactinomas operated over 10 years, with a mean follow-up of 59.

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Background: Pachymeningeal disease (PMD) is a newly recognized pattern of brain metastasis (BrM) failure that specifically occurs following surgery with adjuvant stereotactic radiosurgery (SRS) and has unique prognostic implications relative to leptomeningeal disease (LMD). Here, we report its prevalence, prognostic implications, and associated risk factors.

Methods: A literature search was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses on PUBMED and Cochrane from January 2000 to June 2023.

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Background And Objectives: Anterior temporal lobectomy and amygdalohippocampectomy is a challenging procedure because of the deep surgical trajectory and complex regional neurovascular anatomy. A thorough knowledge of the involved anatomic structures is crucial for a safe and effective procedure. Our objective is to explore the white matter pathways in or around the operative corridor and to illuminate the 3-dimensional relationships of the pertinent operative parenchymal and skull base anatomy, aiming to inform and simplify surgical practice.

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