The difficulties of behavioral evaluation of prolonged disorders of consciousness (DOC) motivate the development of brain-based diagnostic approaches. The perturbational complexity index (PCI), which measures the complexity of electroencephalographic (EEG) responses to transcranial magnetic stimulation (TMS), showed a remarkable sensitivity in detecting minimal signs of consciousness in previous studies. Here, we tested the reliability of PCI in an independently collected sample of 24 severely brain-injured patients, including 11 unresponsive wakefulness syndrome (UWS), 12 minimally conscious state (MCS) patients, and 1 emergence from MCS patient. We found that the individual maximum PCI value across stimulation sites fell within the consciousness range (i.e., was higher than PCI*, which is an empirical cutoff previously validated on a benchmark population) in 11 MCS patients, yielding a sensitivity of 92% that surpassed qualitative evaluation of resting EEG. Most UWS patients (n = 7, 64%) showed a slow and stereotypical TMS-EEG response, associated with low-complexity PCI values (i.e., ≤PCI*). Four UWS patients (36%) provided high-complexity PCI values, which might suggest a covert capacity for consciousness. In conclusion, this study successfully replicated the performance of PCI in discriminating between UWS and MCS patients, further motivating the application of TMS-EEG in the workflow of DOC evaluation.

Background: Navigated repetitive transcranial magnetic stimulation (rTMS) is a promising tool for neuromodulation. In previous studies it has been shown that the activity of the default mode network (DMN) areas, particularly of its key region—the angular gyrus—is positively correlated with the level of consciousness. Our study aimed to explore the effect of rTMS of the angular gyrus as a new approach for disorders of consciousness (DOC) treatment; Methods: A 10-session 2-week high-frequency rTMS protocol was delivered over the left angular gyrus in 38 DOC patients with repeated neurobehavioral assessments obtained at baseline and in 2 days after the stimulation course was complete; Results: 20 Hz-rTMS over left angular gyrus improved the coma recovery scale revised (CRS-R) total score in minimally conscious state (MCS) patients. We observed no effects in vegetative state (VS) patients; and Conclusions: The left angular gyrus is likely to be effective target for rTMS in patients with present signs of consciousness.

Introduction: The aim of the study was to develop and validate a Russian adaptation of the Coma Recovery Scale–Revised (CRS-R). Subjects and methods: We evaluated 58 patients with chronic disorders of consciousness (> 4 weeks post-injury, DOC) of various etiology and two patients in a locked-in state at different stages after coma. We tested sensitivity for changes over 1 week, reliability, criterion validity and diagnostic sensitivity of the Russian adaptation of the CRS-R in comparison with the Russian adaptations of Full Outline of UnResponsiveness Score (FOUR), and Glasgow Coma Scale (GCS). Results: We obtained good sensitivity for changes in neurological status over week (p < 0.0001) and good test-retest reliability (r = 0.997, p < 0.0001) of the CRS-R. Inter-rater reliability was good (κ = 0.99, p < 0.001). We showed high internal consistency (α = 0.87) of the scale and good criterion validity between other scales (r = 0.597 for GCS, and r = 0.900 for FOUR). CRS-R also demonstrated a higher sensitivity in differential diagnosis of DOC, as compared to GCS, and FOUR Score (p < 0.001). Conclusion: The results show that the Russian version of the CRS-R is a valid and sensitive tool for the evaluation of patients with chronic DOC, which can be used for differential diagnosis and for recovery assessment.

Differential diagnosis of unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS) is one of the most challenging problems for specialists who deal with chronic disorders of consciousness (DOC). The aim of the current study was to develop a conventional MRI-based scale and to evaluate its role in distinguishing chronic disorders of consciousness (Disorders of Consciousness MRI-based Distinguishing Scale, DOC-MRIDS). Data were acquired from 30 patients with clinically diagnosed chronic disorders of consciousness. All patients underwent conventional MRI using a Siemens Verio 3.0 T scanner, which included T2 and T1 sequences for patient assessment. Diffuse cortical atrophy, ventricular enlargement, sulcal widening, leukoaraiosis, brainstem and/or thalamus degeneration, corpus callosum degeneration, and corpus callosum lesions were assessed according to DOC-MRIDS criteria, with a total score calculation. The ROC-analysis showed that a reasonable threshold DOC-MRIDS total score was 5.5, that is, patients with DOC-MRIDS total score of 6 and above were classified as UWS and 5 and below as MCS, with sensitivity of 82.4% and specificity of 92.3%. The novel structural MRI-based scale for the assessment of typical brain lesions in patients with chronic DOC is relatively easy to apply, and provides good specificity and sensitivity values for discrimination between UWS and MCS.

Chronic disorders of consciousness (DOC) represent severe central nervous system damage resulting in long-term disability and a significant burden to healthcare institutions and patientsʼ families. DOC develop in patients after coma and are characterized by the presence of wakefulness with complete or almost complete absence of signs of awareness. DOC include vegetative state (VS) and minimally conscious state (MCS). The term prolonged disorders of consciousness (pDOC) is also used in the Russian literature to describe the initial stages of chronic DOC. Another clinical entity, exit from MCS, is used to characterize the stage of recovery of cognitive functions. Diagnosis of DOC is based on repeated structured clinical examination using specific scales, provided that reversible causes of impaired consciousness are excluded. Treatment of DOC patients includes maintenance of vital functions and optimal nutrition and control of typical complications and concomitant conditions (pressure sores, spasticity, pain, paroxysmal sympathetic hyperactivity, etc.). Rehabilitation of DOC patients should involve a multidisciplinary rehabilitation team, the extent of which is determined by the individual problems and capabilities of the patient. Rehabilitation is most effective if started early. To date, there is no robust evidence on the effectiveness of specific methods for restoring consciousness, while a number of pharmacological and non-pharmacological interventions are being studied; however, they should be applied provided that the maximum possible level of correction of the patientʼs somatic problems is achieved. The family plays a key role in rehabilitation. They need practical information about their loved oneʼs condition, guidance in rehabilitation, and psychological support. Хронические нарушения сознания (ХНС) представляют собой синдромы тяжелого поражения центральной нервной системы, приводящие к длительной грубой инвалидизации и требующие значительных усилий по лечению и реабилитации, которые ложатся на медицинские учреждения и на плечи близких пациентов. ХНС развиваются у пациентов после комы и характеризуются наличием бодрствования при полном или практически полном отсутствии признаков осознанного поведения. К ХНС относятся вегетативное состояние (ВС) и состояние минимального сознания (СМС). Также для описания начальных стадий этих состояний используется термин «продленное нарушение сознания» (ПНС). Отдельно выделяют выход из СМС — состояние, которое формируется по мере восстановления когнитивных функций. Диагностика ХНС основывается на многократном структурированном клиническом осмотре с применением специализированных шкал при условии исключения обратимых причин нарушения сознания. Лечение пациентов с ХНС включает в себя поддержание жизненно важных функций, обеспечение оптимального питания и борьбу с типичными осложнениями и сопутствующими состояниями (пролежни, спастичность, боль, пароксизмальная симпатическая гиперактивность и др.). У пациентов с ХНС должна проводиться реабилитация с участием мультидисциплинарной реабилитационной команды в объеме, который определяется проблемами и возможностями конкретного пациента. Наиболее эффективной реабилитация является при условии ее раннего начала. На данный момент однозначных доказательств эффективности каких-либо специфических методов, направленных на восстановление сознания, не получено; изучается ряд соответствующих фармакологических и нефармакологических вмешательств, обязательным условием применения которых является максимально возможная коррекция соматических проблем пациента. Важную роль в ведении пациентов с ХНС играет вовлечение близких пациента, которые, в свою очередь, нуждаются в получении объективной практической информации о состоянии своего родственника и о направлениях реабилитации, а также в психологической помощи.

Diagnostic accuracy of different chronic disorders of consciousness (DOC) can be affected by the false negative errors in up to 40% cases. In the present study, we aimed to investigate the feasibility of a non-Gaussian diffusion approach in chronic DOC and to estimate a sensitivity of diffusion kurtosis imaging (DKI) metrics for the differentiation of vegetative state/unresponsive wakefulness syndrome (VS/UWS) and minimally conscious state (MCS) from a healthy brain state. We acquired diffusion MRI data from 18 patients in chronic DOC (11 VS/UWS, 7 MCS) and 14 healthy controls. A quantitative comparison of the diffusion metrics for grey (GM) and white (WM) matter between the controls and patient group showed a significant (p < 0.05) difference in supratentorial WM and GM for all evaluated diffusion metrics, as well as for brainstem, corpus callosum, and thalamus. An intra-subject VS/UWS and MCS group comparison showed only kurtosis metrics and fractional anisotropy differences using tract-based spatial statistics, owing mainly to macrostructural differences on most severely lesioned hemispheres. As a result, we demonstrated an ability of DKI metrics to localise and detect changes in both WM and GM and showed their capability in order to distinguish patients with a different level of consciousness.