Abstract
ObjectivesNewly diagnosed focal epilepsy (NDfE) is rarely studied, particularly using advanced neuroimaging techniques. Many patients with NDfE experience cognitive impairments, particularly with respect to memory, sustained attention, mental flexibility, and executive functioning. Cognitive impairments have been related to alterations in resting‐state functional brain networks in patients with neurological disorders. In the present study, we investigated whether patients with NDfE had altered connectivity in large‐scale functional networks using resting‐state functional MRI.MethodsWe recruited 27 adults with NDfE and 36 age‐ and sex‐matched healthy controls. Resting‐state functional MRI was analyzed using the Functional Connectivity Toolbox (CONN). We investigate reproducibly determined large‐scale functional networks, including the default mode, salience, fronto‐parietal attention, sensorimotor, and language networks using a seed‐based approach. Network comparisons between patients and controls were thresholded using a FDR cluster‐level correction approach.ResultsWe found no significant differences in functional connectivity between seeds within the default mode, salience, sensorimotor, and language networks and other regions of the brain between patients and controls. However, patients with NDfE had significantly reduced connectivity between intraparietal seeds within the fronto‐parietal attention network and predominantly frontal and temporal cortical regions relative to controls; this finding was demonstrated including and excluding the patients with brain lesions. No common alteration in brain structure was observed in patients using voxel‐based morphometry. Findings were not influenced by treatment outcome at 1 year.ConclusionsPatients with focal epilepsy have brain functional connectivity alterations at diagnosis. Functional brain abnormalities are not necessarily a consequence of the chronicity of epilepsy and are present when seizures first emerge.
Highlights
Neuroimaging approaches have provided important insights into long‐standing, typically treatment‐refractory epilepsy
We observed significantly reduced connectivity between intrapa‐ rietal seeds within the fronto‐parietal attention network and distal brain regions in patients; this hypoconnectivity was demonstrated when all patients were compared with controls and when analyses were restricted to nonlesional patients
We reported focal cortical dysplasia in 7% and subtle signs of unilateral hippocampal sclerosis in 7% of patients. Previous reports of these abnormalities have ranged from 1.5% to 11% of adults with Newly diagnosed focal epilepsy (NDfE) (Liu et al, 2002; Van Paesschen et al, 1997, 1998); 63% of our patients were seizure free after a 1‐year follow‐up, which is in keeping with large clinical studies
Summary
Neuroimaging approaches have provided important insights into long‐standing, typically treatment‐refractory epilepsy. Three of the most in‐ vestigated networks include the default mode network (key role in internally directed or self‐generated thought; Andrews‐Hanna, Smallwood, & Spreng, 2014; Greicius, Krasnow, Reiss, & Menon, 2003; Raichle et al, 2001) has dynamic roles in cognitive processing (Ichesco et al, 2012) and is compromised in patients with loss of consciousness (Vanhaudenhuyse et al, 2010), the salience network (key roles in communication, social behaviour, self‐awareness, and multiple facets of cognition; Menon, 2015), and the fronto‐parietal attention network (key roles in attention, cognitive control, and ex‐ ecutive functioning; Markett et al, 2014; Schmidt, Burge, Visscher, & Ross, 2016) Alterations in these three functional networks have been reported in patients with chronic temporal lobe epilepsy and idiopathic generalized epilepsy (de Campos, Coan, Lin Yasuda, Casseb, & Cendes, 2016; Kay et al, 2013; Wei et al, 2015), and such alterations have been inferred to underlie cognitive impairment in. In order to determine whether functional net‐ work alterations existed in patients in the absence of gross struc‐ tural abnormalities, we performed voxel‐based morphometry (VBM) comparisons of regional grey matter volume between patients and controls (Keller & Roberts, 2008; Keller et al, 2015)
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