Assessing level of consciousness and cognitive changes from vegetative state to full recovery

Abstract

Although investigations addressing cognitive recovery from the vegetative state have been reported, to date there have been no detailed studies of these patients combining both neuropsychology and functional imaging to monitor and record the recovery of consciousness. This paper describes the recovery of a specific vegetative state (VS) case. The patient (OG) remained in the vegetative state for approximately two months, increasing her level of awareness to a minimally conscious state, where she continued for approximately 70 days. In the course of the ensuing 18 months, she was able to reach an acceptable level of cognitive functioning, with partial levels of independence. Throughout this two year period, she received continuous cognitive evaluation, for which several different tools were applied including coma and low functioning scales, full cognitive batteries, and structural and functional magnetic resonance imaging (MRI). We present here preliminary data on fMRI using a word presentation paradigm before and after recovery; we also discuss the difficulty of how to determine level of consciousness using the tools currently available, and the subsequent improvement in different cognitive domains. We confirm that accurate diagnosis and proper cognitive assessment are critical for the rehabilitation of patients with disorders of consciousness.

Neuroimaging activation studies in the vegetative state: predictors of recovery?

“…The fMRI study performed after recovery showed more widespread activation encompassing the language networks. 17 Using a hierarchical auditory stimulation paradigm in fMRI, Coleman et al 13 reported seven VS patients, three of whom (one traumatic and two non-traumatic) showed temporal activation in the low-level auditory contrast (all sounds versus silence) and mid-level speech perception contrast (meaningful speech versus signal-correlated noise). 18,19 The remaining four patients showed no activation in response to sound compared with silence.…”

“…All in all, eight PET studies including 32 patients [6][7][8][9][10][11]16,18,23 and six fMRI studies including 17 patients 12,13,15,[17][18][19][20][21] (one patient was studied by both PET and fMRI) have been reviewed (Table 1). Among these 48 patients (16 of whom were traumatic), 25 patients (52%; 8 traumatic) showed typical activation patterns, five patients (10%; 1 traumatic) showed no activation and 18 patients (38%; 7 traumatic) showed atypical activation patterns.…”

“…Noxious somatosensory stimuli activated midbrain, contralateral thalamus, and primary somatosensory cortex in each and every patient with VS, even in the absence of detectable cortical evoked potentials. The activated primary 17 2 months superior temporal gyri and striate cortex Staffen et al (2006) 21 NT-Hypoxic fMRI SON vs another name Bilateral MPFC left Remained VS Atypical (n=1) 10 months temporoparietal and superior frontal cortex continued somatosensory cortex was functionally disconnected from 'higher order' associative cortical areas, encompassing anterior cingulate, insular, prefrontal and posterior parietal cortices. In healthy controls, such stimuli activated primary and secondary somatosensory cortices, bilateral insular, posterior parietal and anterior cingulate cortices.…”

Electroencephalography (EEG) and Unconsciousness

“…Some MCS patients may retain widely distributed cortical systems with potential for cognitive and sensory function, despite their inability to follow simple instructions or communicate reliably (Schiff et al , 2005). PET and fMRI case reports incorporating complex auditory stimuli have shown large-scale network activation in the minimally conscious state that is not observed in unconscious vegetative patients (Bekinschtein et al , 2005, Laureys et al , 2004b.…”

“…In some fMRI or/and PET studies, patients with higher-level associative cortical activation in VS progressed to MCS or recovered consciousness (Bekinschtein, Tiberti, 2005, Coleman et al , 2007, Di et al , 2007, which seem to show that atypical 'higher order' associative cortical activation in VS heralds recovery of some level of consciousness some months later. Other VS patients with 'higher level' associative cortical activation failed to subsequently recover (Staffen et al , 2006), which was in line with the viewpoint that VS patients with atypical behavioral fragments can show residual isolated brain processing in the absence of clinical recovery (Schiff et al , 2002) .…”