Impaired consciousness in epilepsy

Blumenfeld, Hal

doi:10.1016/s1474-4422(12)70188-6

“…27 The posterior default mode network and related subcortical structures have been associated with the loss of consciousness during seizures. 31 The increased default mode network-pulvinar FCS in the current study is in accord with findings that default mode network activity increases several seconds before seizure onset. 32 Given that the default mode network-pulvinar network is associated with the default state of the human brain, 31 increased synchrony with thalamic nuclei in the interictal or preictal state may facilitate seizures.…”

Section: -24supporting

confidence: 91%

“…31 The increased default mode network-pulvinar FCS in the current study is in accord with findings that default mode network activity increases several seconds before seizure onset. 32 Given that the default mode network-pulvinar network is associated with the default state of the human brain, 31 increased synchrony with thalamic nuclei in the interictal or preictal state may facilitate seizures. 33 In the temporal-thalamic network, the morphometric features of the posterior part of the middle temporal gyrus showed stronger correlation with those of the thalamus in patients with IGE than in controls.…”

Section: -24supporting

confidence: 91%

Identifying Corticothalamic Network Epicenters in Patients with Idiopathic Generalized Epilepsy

Ji

¹

,

Zhang²,

Xu³

et al. 2015

AJNR Am J Neuroradiol

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“…Similar results have been observed in slow wave sleep and general anesthesia [(for review see 21)]. Interestingly, these findings were also confirmed in transient dissociative states of unresponsive wakefulness such as absence seizures, complex partial seizures or sleepwalking -all characterized by preserved automatic reflex motor behavior in the absence of response to commands and showing transient impaired activity in the fronto-temporo-parietal associative cortical network [2,22].…”

Section: Tracking the Recovery Of Consciousness Networksupporting

confidence: 77%

Consciousness supporting networks

Demertzi¹,

Soddu²,

Laureys³

2013

Current Opinion in Neurobiology

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. Author's personal copy In most cases authors Consciousness supporting networksAthena Demertzi, Andrea Soddu and Steven LaureysFunctional neuroimaging shows that patients with disorders of consciousness exhibit disrupted system-level functional connectivity. Unresponsive/''vegetative state'' patients preserve wakefulness networks of brainstem and basal forebrain but the cerebral networks accounting for external perceptual awareness and internal self-related mentation are disrupted. Specifically, the 'external awareness' network encompassing lateral fronto-temporo-parietal cortices bilaterally, and the 'internal awareness' network including midline anterior cingulate/mesiofrontal and posterior cingulate/ precuneal cortices, are functionally disconnected. By contrast, patients in minimally conscious state 'minus', who show nonreflex behaviors, are characterized by right-lateralized recovery of the external awareness network. Similarly, patients who evolve to minimally conscious state 'plus' and respond to commands recover the dominant left-lateralized language network. Now, the use of active experimental paradigms targeting at detecting motor-independent signs of awareness or even establishing communication with these patients, challenge these two clinical boundaries. Such advances are naturally accompanied by legitimate neuroscientific and ethical queries demanding our attention on the medical implementations of this new knowledge. What is 'minimally conscious'?At present there is no generally accepted definition of consciousness [1]. As clinicians, we will reduce the complexity of this term and define consciousness operationally, separating two main components: wakefulness and awareness [2]. Wakefulness has been shown to critically depend upon the functional integrity of subcortical arousal systems over 50 years ago [(e.g., see 3)]. The level of wakefulness can be estimated by simple behavioral criteria based on eye opening ranging from absent, over stimulus-induced to spontaneous sustained eye opening.For instance, every night when falling asleep, we experience a decrease of the level of wakefulness up to the point we lose awareness of our environment. Awareness is more difficult to define and more challenging to assess behaviorally [4]. We have recently proposed to reduce the phenomenological complexity of awareness into two further components: external awareness, namely everything we perceive through our senses (what we see, hear, feel, smell and taste), and internal awareness or stimulusindependent thoughts. Interestingly, the switch between the external and internal milieu was found not only to characterize overt...

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“…Conventional brain structural imaging studies have shown heterogeneous lesion patterns in DOC, suggesting that no specific brain region can be unequivocally related to awareness [16]. This is supported by observations in transient unconscious states, such as during epileptic seizures, where the core pathology is related to the abnormality of brain function rather than macroscopic structure [17]. Nonetheless, widespread diffuse axonal injury and thalamic damage have been observed in patients with VS/UWS following traumatic brain injury [18,19], supporting the role of the thalamus and cerebral cortex in the genesis of awareness.…”

Section: Disorders Of Consciousness and Neural Correlates Of Awarenessmentioning

confidence: 87%

Functional neuroanatomy of disorders of consciousness

Perri

¹

,

Stender

²

,

Laureys

³

et al. 2014

Epilepsy & Behavior

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. Our understanding of the mechanisms of loss and recovery of consciousness, following severe brain injury or during anesthesia, is changing rapidly. Recent neuroimaging studies have shown that patients with chronic disorders of consciousness and subjects undergoing general anesthesia present a complex dysfunctionality in the architecture of brain connectivity. At present, the global hallmark of impaired consciousness appears to be a multifaceted dysfunctional connectivity pattern with both within-network loss of connectivity in a widespread frontoparietal network and between-network hyperconnectivity involving other regions such as the insula and ventral tegmental area. Despite ongoing efforts, the mechanisms underlying the emergence of consciousness after severe brain injury are not thoroughly understood. Important questions remain unanswered: What triggers the connectivity impairment leading to disorders of consciousness? Why do some patients recover from coma, while others with apparently similar brain injuries do not? Understanding these mechanisms could lead to a better comprehension of brain function and, hopefully, lead to new therapeutic strategies in this challenging patient population.This article is part of a Special Issue entitled Epilepsy and Consciousness.

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Impaired consciousness in epilepsy

Cited by 303 publications

References 135 publications

Identifying Corticothalamic Network Epicenters in Patients with Idiopathic Generalized Epilepsy

Identifying Corticothalamic Network Epicenters in Patients with Idiopathic Generalized Epilepsy

Consciousness supporting networks

Functional neuroanatomy of disorders of consciousness

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