Transient effects of tumor location on the functional architecture at rest in glioblastoma patients: three longitudinal case studies

Abstract

BackgroundThe cognitive function of brain tumor patients is affected during the treatment. There is evidence that gliomas and surgery alter the functional brain connectivity but studies on the longitudinal effects are lacking.MethodsWe acquired longitudinal (pre- and post-radiotherapy) resting-state functional magnetic resonance imaging on three selected glioblastoma patients. These cases were selected to study three models: a lesion involving a functional hub within a central system, a lesion involving a peripheral node within a central system and a lesion involving a peripheral node of a non-central system.ResultsWe found that, as expected, the tumor lesion affects connections in close vicinity, but when the lesion relates to a functional hub, these changes involve long-range connections leading to diverse connectivity profiles pre- and post-radiotherapy. In particular, a global but temporary improvement in the post-radiotherapy connectivity was obtained when treating a lesion close to a network hub, such as the posterior Cingulate Cortex.ConclusionsThis suggests that this node re-establishes communication to nodes further away in the network. Eventually, these observed effects seem to be transient and on the long-term the tumor burden leads to an overall decline of connectivity following the course of the pathology. Furthermore, we obtained that the link between hubs, such as the Supplementary Motor Area and posterior Cingulate Cortex represents an important backbone by means of which within and across network communication is handled: the disruption of this connection seems to imply a strong decrease in the overall connectivity.

Distributed changes of the functional connectome in patients with glioblastoma

“…So far, only few studies have investigated the impact of neurosurgery on the brain’s functional network structure. Together they suggest a transient decrease in spontaneous neuronal activity in the cerebellum and reduced connectivity among default mode regions or interhemispheric connections of motor areas, all of which typically resolve within 3 months 30 , 36 , 37 . Our findings corroborate previous results and first demonstrate near total or supra-total recovery of functional network activity upon GBM surgery.…”

Role of Functional Imaging Techniques to Assess Motor and Language Cortical Plasticity in Glioma Patients: A Systematic Review

“…Small tumor volume as well as sharp radiologically defined tumor borders was found in patients with a high level of plastic rearrangements, during repeated awake surgeries [50, 51]. Apart from tumor-related characteristics, other factors that may interfere with the functional cerebral activity, and consequently on plasticity process, comprise anticonvulsants and adjuvant therapy (chemotherapy and radiotherapy), frequency of seizures [74, 75], and subjects' related characteristics (i.e., age), as showed in stroke patients [76].…”

Connectomic profile and clinical phenotype in newly diagnosed glioma patients

“…The DMN, which encompasses the posterior cingulate cortex (PCC), precuneus, medial prefrontal and lateral parietal regions is most active and connected during rest, but also plays a major role in distribution of information processing during active tasks ( Anticevic et al, 2012 , Buckner and Vincent, 2007 , Raichle et al, 2001 ). In glioma, the DMN seems to show either reduced or increased connectivity strength depending on the specific study, which may or may not correlate with clinical status and/or tumor grade ( Esposito et al, 2012 , Ghumman et al, 2016 , Harris et al, 2014 , Tuovinen et al, 2016 , Xu et al, 2013 , Zhang et al, 2016 ). However, these studies did not assess the fundamental alterations in patients' full connectomic profiles at diagnosis.…”