Unconsciousness as the main nonfocal symptom of anterior circulation transient ischemic attack: A case report.

RATIONALE: Unconsciousness is a nonfocal symptom of transient ischemic attack (TIA) that is frequently observed in patients with vertebrobasilar artery stenosis or occlusion. Conversely, loss of consciousness due to anterior circulation involvement (e.g., middle cerebral artery [MCA]) is a rare occurrence in TIA. PATIENT CONCERNS: This report describes a rare case in a 59-year-old woman who experienced recurrent episodes of altered consciousness because of the occlusion or stenosis of her MCAs. DIAGNOSES: The diagnosis of the case was updated from TIA to acute cerebral infarction, finally. Following initial loss of consciousness, cranial magnetic resonance imaging (MRI) did not reveal any evidence of acute cerebral infarction. However, following the second and third episodes of unconsciousness, the MRI revealed multiple new acute cerebral infarcts affecting both the cerebral hemispheres. Further evaluation through digital subtraction angiography disclosed complete occlusion of the left MCA and severe stenosis of the right MCA. INTERVENTIONS: Early in her illness, the patient was treated with vasodilators, aspirin and atorvastatin. Finally, 2 stents in her right and left MCAs were placed respectively, followed by treatment with aspirin, clopidogrel, and double-dosed atorvastatin calcium. Meanwhile, the patient focused on avoiding conditions which may lead to dehydration in her daily life routine. OUTCOMES: The episodes of unconsciousness of this patient were completely resolved. During the 1-year postoperative follow-up, the patient remained clinically stable without any symptoms of unconsciousness, limb numbness or weakness, or dizziness. LESSONS: These findings suggested that hypoperfusion in the bilateral cerebral hemispheres played a pivotal role in precipitating the patient episodes of unconsciousness. This case underscores the possibility that occlusion or severe stenosis in both MCAs can contribute to recurrent episodes of unconsciousness due to hypoperfusion. Moreover, it emphasizes the association between these episodes of unconsciousness and an increased risk of subsequent ischemic stroke.

G-Induced Loss of Consciousness Prediction Using a Support Vector Machine.

INTRODUCTION: Gravity-induced loss of consciousness (G-LOC) is a major threat to fighter pilots and may result in fatal accidents. The brain has a period of 5-6 s from the onset of high +Gz exposure, called the functional buffer period, during which transient ischemia is tolerated without loss of consciousness. We tried to establish a method for predicting G-LOC within the functional buffer period by using machine learning. We used a support vector machine (SVM), which is a popular classification algorithm in machine learning.METHODS: The subjects were 124 flight course students. We used a linear soft-margin SVM, a nonlinear SVM Gaussian kernel function (GSVM), and a polynomial kernel function, for each of which 10 classifiers were built every 0.5 s from the onset of high +Gz exposure (Classifiers 0.5-5.0) to predict G-LOC. Explanatory variables used for each SVM were age, height, weight, with/without anti-G suit, +Gz level, cerebral oxyhemoglobin concentration, and deoxyhemoglobin concentration.RESULTS: The performance of GSVM was better than that of other SVMs. The accuracy of each classifier of GSVM was as follows: Classifier 0.5, 58.1%; 1.0, 54.8%; 1.5, 57.3%; 2.0, 58.1%; 2.5, 64.5%; 3.0, 63.7%; 3.5, 65.3%; 4.0, 64.5%; 4.5, 64.5%; and 5.0, 64.5%.CONCLUSION: We could predict G-LOC with an accuracy rate of approximately 65% from 2.5 s after the onset of high +Gz exposure by using GSVM. Analysis of a larger number of cases and factors to enhance accuracy may be needed to apply those classifiers in centrifuge training and actual flight.Ohrui N, Iino Y, Kuramoto K, Kikukawa A, Okano K, Takada K, Tsujimoto T. G-induced loss of consciousness prediction using a support vector machine. Aerosp Med Hum Perform. 2024; 95(1):29-36.

Hypoxic loss of consciousness in air diving: two cases of mixtures made hypoxic by oxidation of the scuba diving cylinder.

Without an adequate supply of oxygen from the scuba apparatus, humans would not be able to dive. The air normally contained in a scuba tank is dry and free of toxic gases. The presence of liquid in the tank can cause corrosion and change the composition of the gas mixture. Various chemical reactions consume oxygen, making the mixture hypoxic. We report two cases of internal corrosion of a scuba cylinder rendering the respired gas profoundly hypoxic and causing immediate hypoxic loss of consciousness in divers.

A framework to simplify paediatric syncope diagnosis.

This paper aims to improve the diagnosis of syncope and transient loss of consciousness (TLOC) in children. Diagnostic problems stem, first, from some causes spanning various disciplines, e.g. cardiology, neurology and psychiatry, while the most common cause, vasovagal syncope, is not embraced by any specialty. Second, clinical variability is huge with overlapping signs and symptoms. Third, the approach to TLOC/syncope of the European Society of Cardiology (ESC) is underused in childcare. We explain the ESC guidelines using an additional paediatric literature review. Classification of TLOC and syncope is hierarchic and based on history taking. Loss of consciousness (LOC) is defined using three features: abnormal motor control including falling, reduced responsiveness and amnesia. Adding a < 5 min duration and spontaneous recovery defines TLOC. TLOC simplifies diagnosis by excluding long LOC (e.g. some trauma, intoxications and hypoglycaemia) and focussing on syncope, tonic-clonic seizures and functional TLOC. Syncope, i.e. TLOC due to cerebral hypoperfusion, is divided into reflex syncope (mostly vasovagal), orthostatic hypotension (mostly initial orthostatic hypotension in adolescents) and cardiac syncope (arrhythmias and structural cardiac disorders). The initial investigation comprises history taking, physical examination and ECG; the value of orthostatic blood pressure measurement is unproven in children but probably low. When this fails to yield a diagnosis, cardiac risk factors are assessed; important clues are supine syncope, syncope during exercise, early death in relatives and ECG abnormalities.  Conclusions: In adults, the application of the ESC guidelines reduced the number of absent diagnoses and costs; we hope this also holds for children. What is Known: • Syncope and its mimics are very common in childhood, as they are at other ages. • Syncope and its mimics provide considerable diagnostic challenges. What is New: • Application of the hierarchic framework of transient loss of consciousness (TLOC) simplifies diagnosis. • The framework stresses history-taking to diagnose common conditions while keeping an eye on cardiac danger signs.

Unconsciousness and amnesia after cross-body electric shocks not involving the head-A prospective cohort study.

INTRODUCTION: Little is known about how electrical current passes through the human body except that it follows the physical rule of least resistance. Whether organs remote from the shortest route of the current can be affected is unknown, as different types of tissue vary in resistance. This may explain why some people exposed to electrical injury report symptoms from the central nervous system (CNS). In this study, we examined the association between exposure to cross-body electrical current and immediate CNS symptoms. MATERIAL AND METHODS: In a prospective cohort study, we followed 6960 members of the Danish Union of Electricians for 26 weeks using weekly questionnaires. We identified 2356 electrical shocks, and for each shock we asked whether the exposure was cross-body or same-side. We excluded those who reported exposure to the head as well as those who could not report the entry and exit points of the current. We examined two outcomes: becoming unconscious or having amnesia of the event. We use percentages to describe the data and logistic regression to analyze the results. RESULTS: We found that unconsciousness and amnesia following electric shocks were rare events (0.6% and 2.2%, respectively). We found an increased risk of reporting unconsciousness and amnesia in those exposed to cross-body electrical shock exposure compared to those with same-side exposure (Odds Ratio 2.60[0.62 to 10.96] and Odds Ratio 2.18[0.87 to 5.48]). CONCLUSION: Although the outcomes investigated are rare, we cannot rule out a possible effect on the CNS when persons are exposed to cross-body electrical current even though it does not pass through the head.

[Giant Mature Cystic Teratoma Causing Loss of Consciousness before Surgery].

A 30-year-old woman who presented loss of consciousness was diagnosed as having large anterior mediastinal tumor. Computed tomography (CT) showed a 17.0×13.0×7.3 cm cystic mass with internal calcification in the anterior mediastinum that was markedly compressing the heart, great vessels, trachea and bronchi. A mature cystic teratoma was suspected, and the mediastinal tumor was resected through a median sternotomy. At the induction of anesthesia to prevent the development of the respiratory and circulatory collapse, the patient was consciously intubated under the right lateral decubitus position while preparing for percutaneous cardiopulmonary support by cardiac surgeons, and the surgery was safely performed. The tumor was pathologically diagnosed as a mature cystic teratoma, and symptoms such as loss of consciousness have disappeared.

Examining Whether Loss of Consciousness Is Associated With Worse Performance on the SCAT5 and Slower Clinical Recovery After Concussion in Professional Athletes.

Video surveillance has almost universally been employed by professional sports to identify signs of concussion during competition. This study examined associations between video-identified possible loss of consciousness (LOC), acute concussion evaluation findings, and recovery time in concussed professional rugby league players. Medical personnel and sideline video operators identified head impact events sustained during three seasons of National Rugby League (NRL) matches to determine the need for further medical evaluation. If a concussion was suspected, players were removed from play and underwent a Head Injury Assessment, including the Sports Concussion Assessment Tool, Fifth Edition (SCAT5). Video footage was later examined to identify signs of possible LOC (i.e., observed LOC, no protective action in the fall, and unresponsiveness or lying motionless). Possible LOC was identified in 99 of the 1706 head impact events (5.8%). The median duration of apparent unresponsiveness was 4.2 sec (M = 7.4, standard deviation [SD] = 12.8, interquartile range [IQR] = 2.5-6.6). In the 661 athletes for whom SCAT5 data were available, those with possible LOC endorsed more SCAT5 symptoms and performed worse on Maddocks questions, Standardized Assessment of Concussion (SAC) total scores, orientation, immediate recall, concentration, and delayed recall. For the 255 players with medically diagnosed concussions, SCAT5 data were available for 245. Concussed players with possible LOC performed significantly worse on Maddocks questions. However, there were no group differences in SCAT5 symptom endorsement, SAC total scores, orientation, immediate recall, concentration, delayed recall, or the modified version of the Balance Error Scoring System (mBESS) total errors. Further, the presence or absence of possible LOC was not associated with number of games missed or time to medical clearance for match play. The duration of possible LOC was not associated with the number of games missed or time to medical clearance for match play. According to video review in NRL players, brief LOC might be more common than previously thought. The present study reveals possible LOC is not predictive of missed games or time to recover following concussion.

Temporary or Permanent? A Clinical Challenge in the Evaluation of Traumatic Brain Injury Patients with Unconsciousness and Normal Initial Head CT.

BACKGROUND: Traumatic brain injury (TBI) patients with unconsciousness and normal initial head computed tomography (CT) present a clinical dilemma for physicians and neurosurgeons in the emergency department (ED). We recorded how long it took for patients to regain consciousness and evaluated the patients' characteristics. METHODS: From 2018 to 2020, TBI patients with unconsciousness and normal initial head CT [Glasgow coma scale (GCS) score < 13, negative CT scan and normal laboratory test results] were evaluated. Patients who regained consciousness were analyzed. Multivariate logistic regression (MLR) analyses were used to evaluate independent factors for regaining consciousness. RESULTS: A total of 77 patients were included in this study. Fifty-eight (75.3%) patients regained consciousness, most within one day (43.1%). Nineteen (24.7%) patients never regained consciousness. MLR analysis showed that initial GCS score (odds 1.85, p = 0.017), early airway protection in ED (odds 25.02, p = 0.018) and 72-h GCS score improvement by two points (odds 0.02, p = 0.001) were independent factors for regaining consciousness. Overall, 94.1% of patients who received early airway protection and improved 2 points in 72-h GCS score regained consciousness. The association between days to M5 status and days to M6 status (consciousness) was highly significant. Fewer days to M5 status were highly associated with needing fewer days to regain consciousness. CONCLUSIONS: For TBI patients with unconsciousness and normal initial head CT, a higher probability of regaining consciousness was observed in those who underwent early airway protection and who improved 2 points in 72-h GCS score. Regaining consciousness within a short period could be expected in patients with M5 status.

Associations among civilian mild traumatic brain injury with loss of consciousness, posttraumatic stress disorder symptom trajectories, and structural brain volumetric data.

Posttraumatic stress disorder (PTSD) is prevalent and associated with significant morbidity. Mild traumatic brain injury (mTBI) concurrent with psychiatric trauma may be associated with PTSD. Prior studies of PTSD-related structural brain alterations have focused on military populations. The current study examined correlations between PTSD, acute mTBI, and structural brain alterations longitudinally in civilian patients (N = 504) who experienced a recent Criterion A traumatic event. Participants who reported loss of consciousness (LOC) were characterized as having mTBI; all others were included in the control group. PTSD symptoms were assessed at enrollment and over the following year; a subset of participants (n = 89) underwent volumetric brain MRI (M = 53 days posttrauma). Classes of PTSD symptom trajectories were modeled using latent growth mixture modeling. Associations between PTSD symptom trajectories and cortical thicknesses or subcortical volumes were assessed using a moderator-based regression. mTBI with LOC during trauma was positively correlated with the likelihood of developing a chronic PTSD symptom trajectory. mTBI showed significant interactions with cortical thickness in the rostral anterior cingulate cortex (rACC) in predicting PTSD symptoms, r = .461-.463. Bilateral rACC thickness positively predicted PTSD symptoms but only among participants who endorsed LOC, p < .001. The results demonstrate positive correlations between mTBI with LOC and PTSD symptom trajectories, and findings related to mTBI with LOC and rACC thickness interactions in predicting subsequent chronic PTSD symptoms suggest the importance of further understanding the role of mTBI in the context of PTSD to inform intervention and risk stratification.

[Transient loss of consciousness]. / Wegrakingen.

Although transient loss of consciousness (TLOC) is a common problem, hospital care for patients with TLOC is characterised by high rates of no diagnosis and misdiagnosis, accompanied by unnecessary hospital admissions and tests. We attribute these problems to increasing specialisation as well as to a blind spot for vasovagal syncope, a condition not claimed by any specialty. We suggest that all doctors seeing patients with TLOC, both in primary and secondary care, should be familiar with the presentations of the relatively harmless vasovagal syncope and the alarm symptoms of potentially life-threatening cardiac syncope. In this article we present some practical pointers to recognise these conditions and answer some frequently-asked questions regarding the diagnosis and treatment of TLOC.

Loss of Consciousness and Cardiac Arrest as an Atypical Presentation of Tubercular Meningitis: A Case Report.

Tubercular meningitis is a devastating presentation of extra pulmonary tuberculosis, with fatality in each case without treatment. A 39 years male, a regular consumer of alcohol and a known case of major depressive disorder, presented with the alleged history of using an electric heater in a closed room, and presented to emergency with unconsciousness and cardiac arrest. As his neurological status didn't improve over 72 hrs, a magnetic resonance imaging brain was done which was non-conclusive. Electroencephalogram revealed diffuse right fronto-parietal seizure activity ceasing with midazolam injection, hence levetiracetam was started. Lumbar puncture revealed increased adenosine deaminase and nil white blood cells. Repeat lumbar puncture showed lymphocytic-predominant pleocytosis, elevated protein and low glucose. The patient was started on anti-tubercular therapy and an injection of dexamethasone was added. Repeat electroencephalogram didn't show any seizure-like activity. It is important to be aware of variety of presentations of tubercular meningitis. Delay in treatment leads to irreversible neurological damage and even death. Keywords: cardiac arrest; case report; tubercular meningitis; unconsciousness.

Proton magnetic resonance spectroscopy changes in the brainstem in patients after mild traumatic brain injury with loss of consciousness.

INTRODUCTION: Loss of consciousness (LOC) is used as a diagnostic feature of mild traumatic brain injury (MTBI). However, only 10% of concussions result in LOC. There are only a limited number of in-vivo studies dealing with unconsciousness and structural and functional integrity of the brainstem in patients with MTBI. The aim of our pilot study was to assess the sensitivity of proton magnetic resonance spectroscopy (1H-MRS) to detect metabolic changes in the brainstem in patients after MTBI with unconscioussness. METHODS: Twenty-four patients (12 with LOC, and 12 without LOC) within 3 days of MTBI and 19 healthy controls were examined. All subjects underwent single-voxel 1H-MRS examination of the upper brainstem. Spectra were evaluated using LCModel software. Ratios of total N-acetylaspartate (tNAA), total choline-containing compounds (tCho) and glutamate plus glutamine (Glx) to total creatine (tCre) were used for calculations. RESULTS: We found a significant decrease in tNAA/tCre and tCho/tCre ratios in the patient group with LOC when compared with the control group of healthy volunteers (P=0.002 and P=0.041, respectively), and a significant decrease in the tNAA/tCre ratio in the LOC group when compared with patients without LOC (P=0.04). Other metabolite ratios in the brainstem did not show any significant group differences. CONCLUSION: Our findings indicate that decrease of tNAA/tCre ratio in the upper brainstem using single-voxel 1H-MRS may provide a potential biomarker for MTBI associated with LOC.

Nurse triage accuracy in the evaluation of syncope according to European Society of Cardiology guidelines.

AIMS: The role of triage for patients admitted to the emergency department (ED) for a syncopal transitory loss of consciousness (TLOC) has not been debated, and no comparisons with the recent European Society of Cardiology (ESC) guidelines are currently available. To verify the ability of triage to correctly prioritize patients with syncopal TLOC. METHODS AND RESULTS: All patients who received a triage assessment at the ED of the Merano Hospital (Italy) between 1 January 2017 and 30 June 2019 for a syncope were considered. All syncope were reclassified according to the aetiology reported in the ESC guidelines. The baseline characteristics of the patients were recorded and divided according to the severity code provided during triage into two study groups: high priority (red/orange) and low priority (yellow/green/blue). The outcome of the study was the presence of a diagnosed cardiac cause within 30 days after the admission. A total of 2066 patients were enrolled (14.3% high priority vs. 85.7% low priority). Cardiac syncope was present in 7.5% of patients. Nurse triage showed a sensitivity for cardiac syncope of 44.8%, a specificity of 88.1%, and an accuracy of 84.9%. The observed discriminatory ability presented an area under the receiver operating characteristic curve of 0.685 (95% confidence interval 0.638-0.732). The possible identification of the aetiology of the syncopal TLOC by the nurse showed good agreement with the medical diagnosis (Cohen's kappa 0.857, P < 0.001). CONCLUSIONS: In cases of syncopal TLOC, nurse triage had a fair specificity but suboptimal sensitivity for cardiac causes. Specific nursing assessments following triage (e.g. precise scores or electrocardiogram) could improve the triage performance.