Reversible post-traumatic bilateral extensive restricted diffusion of the brain. A case study and review of the literature

Traumatic brain injury and disorders of consciousness

Trauma is one of the most common causes of disorders of consciousness (DOC) worldwide. Traumatic brain injury (TBI) leads to heterogeneous, multifocal injury via focal brain damage and diffuse axonal injury, causing an acquired network disorder. Recovery occurs through reemergence of dynamic cortical and subcortical networks. Accurate diagnostic evaluation is essential toward promoting recovery and may be more challenging in traumatic than non-traumatic brain injuries. Standardized neurobehavioral assessment is the cornerstone for assessments in the acute, prolonged, and chronic phases of traumatic DOC, while structural and functional neuroimaging, tractography, nuclear medicine studies, and electrophysiologic techniques assist with differentiation of DOC states and prognostication. Prognosis for recovery is better for patients with TBI than those with non-traumatic brain injuries, and the timeline for recovery is longer. The majority of patients experience improvement in their DOC within the first year post-injury, but recovery can continue for five and even ten years after TBI. Pharmacologic therapy and device-related neuromodulation represent important areas for future research.

Recovery of consciousness after acute brain injury: a narrative review

BACKGROUND

Disorders of consciousness (DoC) are frequently encountered in both, acute and chronic brain injuries. In many countries, early withdrawal of life-sustaining treatments is common practice for these patients even though the accuracy of predicting recovery is debated and delayed recovery can be seen. In this review, we will discuss theoretical concepts of consciousness and pathophysiology, explore effective strategies for management, and discuss the accurate prediction of long-term clinical outcomes. We will also address research challenges.

MAIN TEXT

DoC are characterized by alterations in arousal and/or content, being classified as coma, unresponsive wakefulness syndrome/vegetative state, minimally conscious state, and confusional state. Patients with willful modulation of brain activity detectable by functional MRI or EEG but not by behavioral examination is a state also known as covert consciousness or cognitive motor dissociation. This state may be as common as every 4th or 5th patient without behavioral evidence of verbal command following and has been identified as an independent predictor of long-term functional recovery. Underlying mechanisms are uncertain but intact arousal and thalamocortical projections maybe be essential. Insights into the mechanisms underlying DoC will be of major importance as these will provide a framework to conceptualize treatment approaches, including medical, mechanical, or electoral brain stimulation.

CONCLUSIONS

We are beginning to gain insights into the underlying mechanisms of DoC, identifying novel advanced prognostication tools to improve the accuracy of recovery predictions, and are starting to conceptualize targeted treatments to support the recovery of DoC patients. It is essential to determine how these advancements can be implemented and benefit DoC patients across a range of clinical settings and global societal systems. The Curing Coma Campaign has highlighted major gaps knowledge and provides a roadmap to advance the field of coma science with the goal to support the recovery of patients with DoC.

Intramyelinic edema manifesting as central white matter diffusion restriction associated with brain contusion in pediatric patients

In traumatic brain injury, white matter diffusion restriction can be an imaging manifestation of non-hemorrhagic axonal injury. In this article, a different pattern of widespread white matter diffusion restriction associated with ipsilateral cortical damage, all noted in pediatric and young adult TBI patients, is presented. Its atypical pattern of distribution and extensive scope on imaging suggest excitotoxicity and intramyelinic edema as possible underlying mechanisms.

Electrophysiological characteristics of CM-pf in diagnosis and outcome of patients with disorders of consciousness

BACKGROUND

Deep brain stimulation (DBS) in the centromedian-parafascicular complex (CM-pf) has been reported as a potential therapeutic option for disorders of consciousness (DoC). However, the lack of understanding of its electrophysiological characteristics limits the improvement of therapeutic effect.

OBJECTIVE

To investigate the CM-pf electrophysiological characteristics underlying disorders of consciousness (DoC) and its recovery.

METHODS

We collected the CM-pf electrophysiological signals from 23 DoC patients who underwent central thalamus DBS (CT-DBS) surgery. Five typical electrophysiological features were extracted, including neuronal firing properties, multiunit activity (MUA) properties, signal stability, spike-MUA synchronization strength (syncMUA), and the background noise level. Their correlations with the consciousness level, the outcome, and the primary clinical factors of DoC were analyzed.

RESULTS

11 out of 23 patients (0/2 chronic coma, 5/13 unresponsive wakefulness syndrome/vegetative state (UWS/VS), 6/8 minimally conscious state minus (MCS-)) exhibited an improvement in the level of consciousness after CT-DBS. In CM-pf, significantly stronger gamma band syncMUA strength and alpha band normalized MUA power were found in MCS- patients. In addition, higher firing rates, stronger high-gamma band MUA power and alpha band normalized power, and more stable theta oscillation were correlated with better outcomes. Besides, we also identified electrophysiological properties that are correlated with clinical factors, including etiologies, age, and duration of DoC.

CONCLUSION

We provide comprehensive analyses of the electrophysiological characteristics of CM-pf in DoC patients. Our results support the 'mesocircuit' hypothesis, one proposed mechanism of DoC recovery, and reveal CM-pf electrophysiological features that are crucial for understanding the pathogenesis of DoC, predicting its recovery, and explaining the effect of clinical factors on DoC.

Prognosis of consciousness disorders in the intensive care unit

Assessments of consciousness are a critical part of prognostic algorithms for critically ill patients suffering from severe brain injuries. There have been significant advances in the field of coma science over the past two decades, providing clinicians with more advanced and precise tools for diagnosing and prognosticating disorders of consciousness (DoC). Advanced neuroimaging and electrophysiological techniques have vastly expanded our understanding of the biological mechanisms underlying consciousness, and have helped identify new states of consciousness. One of these, termed cognitive motor dissociation, can predict functional recovery at 1 year post brain injury, and is present in up to 15-20% of patients with DoC. In this chapter, we review several tools that are used to predict DoC, describing their strengths and limitations, from the neurological examination to advanced imaging and electrophysiologic techniques. We also describe multimodal assessment paradigms that can be used to identify covert consciousness and thus help recognize patients with the potential for future recovery and improve our prognostication practices.

Diffuse subcortical white matter restriction: An uncommon finding on metronidazole toxicity

Metronidazole is a common and widely used antibiotic to treat a wide range of infectious diseases and has been associated with serious neurologic disturbances which in some cases were irreversible. We present a metronidazole-induced encephalopathy in a 19-year-old girl after 7 days of metronidazole treatment, with diffusion restricted subcortical white matter lesions along with the corpus callosum involvements. Diverse clinical presentation of a serious neurologic disturbance caused by a common widely used antibiotic should be carefully addressed in the setting of both short- and long-term treatment.

Unusual Magnetic Resonance Imaging Findings Contrast-induced Encephalopathy following Cerebral Angiography

<p>Contrast-induced encephalopathy (CIE) following cerebral angiography has similar clinical presentations to ischemic complications of cerebral angiography. Neurologic deficits in CIE are mostly transient, but those caused by acute cerebral infarction (ACI) as ischemic complications of cerebral angiography may be permanent. Therefore, distinguishing CIE from ACI is important. Diffusion restriction on magnetic resonance imaging (MRI) implies ACI, while hyperintensity on diffusion weighted imaging (DWI) without correlation on the apparent diffusion coefficient (ADC) map implies CIE. We reported a rare case of CIE with diffusion restriction on MRI following cerebral angiography that mimicked MRI findings of ACI. The mechanism of this phenomenon remains unknown and requires further investigation.

Recovery from disorders of consciousness: mechanisms, prognosis and emerging therapies

Substantial progress has been made over the past two decades in detecting, predicting and promoting recovery of consciousness in patients with disorders of consciousness (DoC) caused by severe brain injuries. Advanced neuroimaging and electrophysiological techniques have revealed new insights into the biological mechanisms underlying recovery of consciousness and have enabled the identification of preserved brain networks in patients who seem unresponsive, thus raising hope for more accurate diagnosis and prognosis. Emerging evidence suggests that covert consciousness, or cognitive motor dissociation (CMD), is present in up to 15-20% of patients with DoC and that detection of CMD in the intensive care unit can predict functional recovery at 1 year post injury. Although fundamental questions remain about which patients with DoC have the potential for recovery, novel pharmacological and electrophysiological therapies have shown the potential to reactivate injured neural networks and promote re-emergence of consciousness. In this Review, we focus on mechanisms of recovery from DoC in the acute and subacute-to-chronic stages, and we discuss recent progress in detecting and predicting recovery of consciousness. We also describe the developments in pharmacological and electrophysiological therapies that are creating new opportunities to improve the lives of patients with DoC.

Clinical trials in traumatic brain injury: cellular therapy and outcome measures

Clinical trials for traumatic brain injury (TBI) have not successfully produced a new therapeutic for neuroprotection or neurorestoration, despite multiple attempts. Stem cell-based therapies and/or cellular therapies have been developed over the past 20 years such that clinical trials are now in Phase II and III stages for neurologic diseases such as TBI and stroke. Many of the vexing issues from past clinical failures still exist today, namely, preclinical data that may not translate to clinical trial because of design and injury heterogeneity that poorly stratifies enrolled patients. Recognition of these problems has led us to advocate for outcome measures that are clinically meaningful, but do not represent a global functional "score." Specifically, we seek to measure those early physiologically relevant outcomes (intracranial pressure, edema, and therapeutic intensity) and later structural outcomes in regions of interest that are linked to putative mechanisms of action of cell based therapies. Early approval of therapeutics that are successful by these metrics would then allow further access to treatments that could be further tested via patient registries and other surveillance for ultimate adoption. Continuing to do the same thing with each iterative trial will assure the same results.

Reversible restricted-diffusion lesion representing transient intramyelinic cytotoxic edema in a patient with traumatic brain injury

We report this case to increase the awareness of magnetic resonance imaging (MRI) features of reversible white matter abnormalities in diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps in a patient with traumatic brain injury (TBI). An eight-year-old girl, who was hit by a truck, was brought to the emergency department by the emergency medical service (EMS). Eleven days later, she experienced cognitive impairment requiring MRI evaluation. DWI and ADC maps showed restricted diffusion in the white matter of the corpus callosum, peri-atrial white matter, and in the right centrum semiovale. There were no significant hemorrhagic foci in these regions, which showed complete resolution on follow up DWI MRI 13 days later. This reported case revealed TBI-related transient reversible intramyelinic cytotoxic edema.

Assessment of neural alterations in obstructive sleep apnoea syndrome: can apparent diffusion coefficient measurements be useful?

BACKGROUND AND AIMS

Our aim was to investigate whether neurological alteration in patients with obstructive sleep apnoea syndrome (OSAS) with apparently normal cerebral and cerebellar structures can be assessed by means of apparent diffusion coefficient (ADC) measurement and to investigate the association between OSAS severity and ADC values.

METHODS

Following the acquisition of diffusion-weighted cranial magnetic resonance imaging, ADC measurements were performed in 24 different apparently normal cerebral and cerebellar structures, including the bilateral frontal and parietal cortices, insulae, cingulate gyri, hippocampi, frontal and parieto-occipital periventricular white matter (PWM), caudate nuclei, putamen, thalami, cerebellar hemispheres, pons and mesencephalon in 47 OSAS patients and 20 control subjects. The ADC values of the patients and the control group were compared. The association between the apnoea-hypopnoea index (AHI) and the ADC values of the patients were investigated.

RESULTS

The ADC values in the bilateral frontal PWM were lower in the patient group than those in the control subjects (P < 0.05). The measurements in the right cingulate gyri of the OSAS patients exhibited significantly higher ADC values than those of the control group (P = 0.002). Bilateral thalamic ADC values in severe OSAS patients were significantly higher than those in mild and moderate OSAS patients (P < 0.05).

CONCLUSION

The ADC measurement is a simple and effective technique to evaluate neural alteration of the brain in patients with OSAS. ADC measurements can also be useful in the evaluation of the association between the AHI and the degree of neural alteration in the central nervous system.

Unexpected recovery of function after severe traumatic brain injury: the limits of early neuroimaging-based outcome prediction

BACKGROUND

Prognostication in the early stage of traumatic coma is a common challenge in the neuro-intensive care unit. We report the unexpected recovery of functional milestones (i.e., consciousness, communication, and community reintegration) in a 19-year-old man who sustained a severe traumatic brain injury. The early magnetic resonance imaging (MRI) findings, at the time, suggested a poor prognosis.

METHODS

During the first year of the patient's recovery, MRI with diffusion tensor imaging and T2*-weighted imaging was performed on day 8 (coma), day 44 (minimally conscious state), day 198 (post-traumatic confusional state), and day 366 (community reintegration). Mean apparent diffusion coefficient (ADC) and fractional anisotropy values in the corpus callosum, cerebral hemispheric white matter, and thalamus were compared with clinical assessments using the Disability Rating Scale (DRS).

RESULTS

Extensive diffusion restriction in the corpus callosum and bihemispheric white matter was observed on day 8, with ADC values in a range typically associated with neurotoxic injury (230-400 × 10(-6 )mm(2)/s). T2*-weighted MRI revealed widespread hemorrhagic axonal injury in the cerebral hemispheres, corpus callosum, and brainstem. Despite the presence of severe axonal injury on early MRI, the patient regained the ability to communicate and perform activities of daily living independently at 1 year post-injury (DRS = 8).

CONCLUSIONS

MRI data should be interpreted with caution when prognosticating for patients in traumatic coma. Recovery of consciousness and community reintegration are possible even when extensive traumatic axonal injury is demonstrated by early MRI.

Formononetin protects TBI rats against neurological lesions and the underlying mechanism

Traumatic brain injury (TBI) is a major cause of disability or death worldwide, especially in the young. Thus, effective medication with few side effects needs to be developed. This work aimed to explore the potential benefits of formononetin (FN) on TBI rodent model and to discuss the regarding mechanism. These findings showed that FN effectively increased the activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in brain tissue of TBI rats (P<0.01), while it reduced intracephalic malonaldehyde (MDA), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) concentrations (P<0.01). Meanwhile, the hydrocephalus in the TBI rat was alleviated, and the injured nerve cell of the lesioned brain was reduced as showed in hematoxylin-eosin (HE) staining assay. In addition, the endogenous mRNA level of cyclooxygenase-2 (COX-2) in the brain of the TBI rat was significantly down-regulated (P<0.01). Furthermore, the protein expression of nuclear factor E2-related factor 2 (Nrf2) was effectively up-regulated (P<0.01). Taken together, we conclude that formononetin mediates the promising anti-TBI effects against neurocyte damage, which the underlying mechanisms are associated with inhibiting intracephalic inflammatory response and oxidative stress for neuroprotection.

Corpus callosum hematoma secondary to cerebral venous malformation presenting as alien hand syndrome

A 26-year-old right-handed female presented with alien hand syndrome (AHS) secondary to corpus callosum (CC) hematoma. The patient had abnormal feelings in the left upper limb and exhibited intermanual conflict. Imaging studies demonstrated acute hemorrhage in the genu and body of the CC secondary to cerebral venous malformation. Callosal hemorrhage is usually caused by head trauma or a ruptured arteriovenous that extends beyond the CC. We report what may be the first case of AHS caused by callosal hemorrhage due to venous malformation.

Advanced neuroimaging in traumatic brain injury

Advances in structural and functional neuroimaging have occurred at a rapid pace over the past two decades. Novel techniques for measuring cerebral blood flow, metabolism, white matter connectivity, and neural network activation have great potential to improve the accuracy of diagnosis and prognosis for patients with traumatic brain injury (TBI), while also providing biomarkers to guide the development of new therapies. Several of these advanced imaging modalities are currently being implemented into clinical practice, whereas others require further development and validation. Ultimately, for advanced neuroimaging techniques to reach their full potential and improve clinical care for the many civilians and military personnel affected by TBI, it is critical for clinicians to understand the applications and methodological limitations of each technique. In this review, we examine recent advances in structural and functional neuroimaging and the potential applications of these techniques to the clinical care of patients with TBI. We also discuss pitfalls and confounders that should be considered when interpreting data from each technique. Finally, given the vast amounts of advanced imaging data that will soon be available to clinicians, we discuss strategies for optimizing data integration, visualization, and interpretation.

Methadone-induced toxic leukoencephalopathy: diagnosis and follow-up by magnetic resonance imaging including diffusion-weighted imaging and apparent diffusion coefficient maps

BACKGROUND AND PURPOSE

Effects of methadone misuse have been rarely described. The purpose of this case report is to increase the knowledge of methadone-related leukoencephalopathy.

METHODS

We report the long-term follow-up by brain magnetic resonance imaging including isotropic diffusion-weighted imaging and mean apparent diffusion coefficient values of a 49-year-old patient who attempted suicide by intravenous methadone.

RESULTS AND CONCLUSIONS

Lesion pattern included subtle cerebellar involvement, mainly reversible extensive bilateral and symmetric brain involvement, cystic degeneration in the periventricular regions, sparing of corpus callosum and subcortical U-fibers, development of diffuse brain atrophy, and clear-cut clinical improvement.