Imaging and neurochemical markers for diagnosis and disease progression in ALS

Enteral tube feeding for amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Maintaining adequate nutrition is critical for people with amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND). Enteral tube feeding is offered to people experiencing difficulty swallowing (dysphagia) to prevent weight loss and aspiration pneumonia. Among the types of enteral tube feeding, percutaneous endoscopic gastrostomy (PEG) is the typical procedure offered to people with ALS and will be mainly discussed here.

OBJECTIVES

To examine the effectiveness of percutaneous endoscopic gastrostomy or other enteral tube feeding in people with ALS, compared to oral feeds without enteral tube feeding on: 1. survival; 2. nutritional status; 3. quality of life. To examine the incidence of minor and major complications of percutaneous endoscopic gastrostomy (PEG) and other enteral tube feeding procedures in people with ALS.

SEARCH METHODS

On 3 January 2020 and 6 February 2021, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE. Embase, ClinicalTrials.gov and WHO ICTRP. We screened the results to identify randomized controlled studies on enteral tube feeding in ALS. We reviewed all references from the search in published articles to identify any additional references.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), quasi-RCTs, and cross-over trials evaluating the effectiveness and complications of PEG or other enteral tube feeding placement in ALS.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We found no RCTs or quasi-RCTs comparing the effectiveness of enteral tube feeding versus oral feeds without enteral tube feeding.

AUTHORS' CONCLUSIONS

There are no RCTs or quasi-RCTs to indicate whether enteral tube feeding is effective compared to continuation of oral feeding for any of the outcome measures. Such RCTs are very unlikely to be performed for ethical reasons. RCTs evaluating the effect of different enteral tube insertion techniques and timings of tube placement on survival and quality of life of people with ALS dysphagia are feasible and warranted.

Neurodegenerative Disorders of Alzheimer, Parkinsonism, Amyotrophic Lateral Sclerosis and Multiple Sclerosis: An Early Diagnostic Approach for Precision Treatment

Neurodegenerative diseases (NDs) are characterised by progressive dysfunction of synapses, neurons, glial cells and their networks. Neurodegenerative diseases can be classified according to primary clinical features (e.g., dementia, parkinsonism, or motor neuron disease), anatomic distribution of neurodegeneration (e.g., frontotemporal degenerations, extrapyramidal disorders, or spinocerebellar degenerations), or principal molecular abnormalities. The most common neurodegenerative disorders are amyloidosis, tauopathies, a-synucleinopathy, and TAR DNA-binding protein 43 (TDP-43) proteopathy. The protein abnormalities in these disorders have abnormal conformational properties along with altered cellular mechanisms, and they exhibit motor deficit, mitochondrial malfunction, dysfunctions in autophagic-lysosomal pathways, synaptic toxicity, and more emerging mechanisms such as the roles of stress granule pathways and liquid-phase transitions. Finally, for each ND, microglial cells have been reported to be implicated in neurodegeneration, in particular, because the microglial responses can shift from neuroprotective to a deleterious role. Growing experimental evidence suggests that abnormal protein conformers act as seed material for oligomerization, spreading from cell to cell through anatomically connected neuronal pathways, which may in part explain the specific anatomical patterns observed in brain autopsy sample. In this review, we mention the human pathology of select neurodegenerative disorders, focusing on how neurodegenerative disorders (i.e., Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis) represent a great healthcare problem worldwide and are becoming prevalent because of the increasing aged population. Despite many studies have focused on their etiopathology, the exact cause of these diseases is still largely unknown and until now with the only available option of symptomatic treatments. In this review, we aim to report the systematic and clinically correlated potential biomarker candidates. Although future studies are necessary for their use in early detection and progression in humans affected by NDs, the promising results obtained by several groups leads us to this idea that biomarkers could be used to design a potential therapeutic approach and preclinical clinical trials for the treatments of NDs.

Functions of p38 MAP Kinases in the Central Nervous System

Mitogen-activated protein (MAP) kinases are a central component in signaling networks in a multitude of mammalian cell types. This review covers recent advances on specific functions of p38 MAP kinases in cells of the central nervous system. Unique and specific functions of the four mammalian p38 kinases are found in all major cell types in the brain. Mechanisms of p38 activation and downstream phosphorylation substrates in these different contexts are outlined and how they contribute to functions of p38 in physiological and under disease conditions. Results in different model organisms demonstrated that p38 kinases are involved in cognitive functions, including functions related to anxiety, addiction behavior, neurotoxicity, neurodegeneration, and decision making. Finally, the role of p38 kinases in psychiatric and neurological conditions and the current progress on therapeutic inhibitors targeting p38 kinases are covered and implicate p38 kinases in a multitude of CNS-related physiological and disease states.

[A prognostic biomarker in amyotrophic lateral sclerosis]

Although we currently have two, approved, disease-modifying drugs for the treatment of amyotrophic lateral sclerosis (ALS), we are in disperate need for more efficacious treatment. To aggressively test for newer therapies, we must develop reliable objective biomarkers to supplement clinical outcome measures. Many biomarker candidates have been actively and vigorously investigated. Among neurophysiological biomarkers, transcranial magnetic stimulation (TMS)-based biomarkers show potential in exploring disease mechanisms. Neuroimaging biomarkers have high specificity in diagnosing ALS but are an expensive endeavor and are not sensitive enough to detect changes over time of the disease. Among fluid-based biochemical biomarkers, creatinine (Crn) and uric acids (UA), which have been known for decades, may prove to be highly promising biomarkers that can predict disease progression. They can be easily tested in any clinical trials because the costs are minimal. Although known for some time, neurofilaments (NF), either phosphorylated-NF heavy subunit (pNFH) or NF light subunit (NFL), have emerged as "new" biomarkers using specific antibodies. They appear to be highly specific and sensitive in diagnosing ALS, yet they may be insensitive to assess changes in disease over time. These two NF biomarkers along with Crn and UA should be explored extensively in future clinical trials and any other clinical studies in ALS. Yet, we still need newer, more innovative, and reliable biomarkers for future ALS research. Fortunatley, aggressive investigations appear to be currently underway.

Non-invasive assessment of disease progression and neuroprotective effects of dietary coconut oil supplementation in the ALS SOD1G93A mouse model: A 1H-magnetic resonance spectroscopic study

Amyotrophic Lateral Sclerosis (ALS) is an incurable neurodegenerative disease primarily characterized by progressive degeneration of motor neurons in the motor cortex, brainstem and spinal cord. Due to relatively fast progression of ALS, early diagnosis is essential for possible therapeutic intervention and disease management. To identify potential diagnostic markers, we investigated age-dependent effects of disease onset and progression on regional neurochemistry in the SOD1^G93A ALS mouse model using localized in vivo magnetic resonance spectroscopy (MRS). We focused mainly on the brainstem region since brainstem motor nuclei are the primarily affected regions in SOD1^G93A mice and ALS patients. In addition, metabolite profiles of the motor cortex were also assessed. In the brainstem, a gradual decrease in creatine levels were detected starting from the pre-symptomatic age of 70 days postpartum. During the early symptomatic phase (day 90), a significant increase in the levels of the inhibitory neurotransmitter γ- aminobutyric acid (GABA) was measured. At later time points, alterations in the form of decreased NAA, glutamate, glutamine and increased myo-inositol were observed. Also, decreased glutamate, NAA and increased taurine levels were seen at late stages in the motor cortex. A proof-of-concept (PoC) study was conducted to assess the effects of coconut oil supplementation in SOD^G93A mice. The PoC revealed that the coconut oil supplementation together with the regular diet delayed disease symptoms, enhanced motor performance, and prolonged survival in the SOD1^G93A mouse model. Furthermore, MRS data showed stable metabolic profile at day 120 in the coconut oil diet group compared to the group receiving a standard diet without coconut oil supplementation. In addition, a positive correlation between survival and the neuronal marker NAA was found. To the best of our knowledge, this is the first study that reports metabolic changes in the brainstem using in vivo MRS and effects of coconut oil supplementation as a prophylactic treatment in SOD1^G93A mice.

Hyperintensity of the corticospinal tract on FLAIR: A simple and sensitive objective upper motor neuron degeneration marker in clinically verified amyotrophic lateral sclerosis

OBJECTIVE

The involvement of upper motor neuron (UMN) degeneration is crucial to the diagnosis of amyotrophic lateral sclerosis (ALS). However, it is difficult to detect in the early stages, and particularly with predominantly lower motor neuron (LMN) dysfunction. Thus, objective and sensitive UMN degeneration markers are needed for an accurate and early diagnosis. Several studies have investigated the abnormal signal changes in brain MRI for patients with ALS, so we hope to develop a neuroimaging diagnosis method in brain MRI that can evaluate UMN degeneration.

MATERIALS AND METHODS

We investigated corticospinal tract (CST) hyperintensity on MRI-fluid attenuated inversion recovery (FLAIR) images for 82 clinically verified ALS patients and 38 age-and gender-matched control subjects. Visual evaluation of the FLAIR images was analyzed independently by 3 observers. The clinical examination was implemented by an experienced neurological physician.

RESULTS

The three observers' views were identical regarding CST hyperintensity on FLAIR images in subcortical precentral gyrus, centrum emiovale, internal capsule, and cerebral peduncles levels (p>0.05). The frequency of CST hyperintensity is significantly higher for the ALS group than the control group in subcortical precentral gyrus, centrum semiovale, posterior limbs of internal capsule and cerebral peduncles levels. (p<0.01). The mean areas under the receiver operating characteristic curves (AUC) values were not different among clinical examinations, CST hyperintensity and mixed-examination (CST hyperintensity and clinical examination groups) in subcortical precentral gyrus, centrum semiovale, internal capsule, and cerebral peduncles levels (p>0.05), although AUC values of CST hyperintensity was slightly higher than clinical examination in centrum semiovale level. There was no statistically significant correlation between CST hyperintensity and age of onset, gender, disease duration, region of onset, and clinical UMN manifestation. (p>0.05).

CONCLUSION

CST hyperintensity was found more frequently in patients with ALS compared to the matched control group. It can be used to evaluate UMN degeneration effectively in subcortical precentral gyrus, centrum semiovale and cerebral peduncles levels. Combining CST hyperintensity and clinical examination can improve the sensitivity of diagnostic performance for UMN degeneration in ALS.

Lessons of ALS imaging: Pitfalls and future directions - A critical review

Background

While neuroimaging in ALS has gained unprecedented momentum in recent years, little progress has been made in the development of viable diagnostic, prognostic and monitoring markers.

Objectives

To identify and discuss the common pitfalls in ALS imaging studies and to reflect on optimal study designs based on pioneering studies.

Methods

A “PubMed”-based literature search on ALS was performed based on neuroimaging-related keywords. Study limitations were systematically reviewed and classified so that stereotypical trends could be identified.

Results

Common shortcomings, such as relatively small sample sizes, statistically underpowered study designs, lack of disease controls, poorly characterised patient cohorts and a large number of conflicting studies, remain a significant challenge to the field. Imaging data of ALS continue to be interpreted at a group-level, as opposed to meaningful individual-patient inferences.

Conclusions

A systematic, critical review of ALS imaging has identified stereotypical shortcomings, the lessons of which should be considered in the design of future prospective MRI studies. At a time when large multicentre studies are underway a candid discussion of these factors is particularly timely.

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Stereotypical shortcomings can be identified in ALS neuroimaging studies.

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A systematic discussion of ALS study limitations is particularly timely.

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Individual patient data meta-analyses and multicentre studies are urgently required.

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The gaps identified in ALS imaging indicate exciting research opportunities.

The utility of independent component analysis and machine learning in the identification of the amyotrophic lateral sclerosis diseased brain

Amyotrophic lateral sclerosis (ALS) is a devastating disease with a lifetime risk of ∼1 in 2000. Presently, diagnosis of ALS relies on clinical assessments for upper motor neuron and lower motor neuron deficits in multiple body segments together with a history of progression of symptoms. In addition, it is common to evaluate lower motor neuron pathology in ALS by electromyography. However, upper motor neuron pathology is solely assessed on clinical grounds, thus hindering diagnosis. In the past decade magnetic resonance methods have been shown to be sensitive to the ALS disease process, namely: resting-state connectivity measured with functional MRI, cortical thickness measured by high-resolution imaging, diffusion tensor imaging (DTI) metrics such as fractional anisotropy and radial diffusivity, and more recently magnetic resonance spectroscopy (MRS) measures of gamma-aminobutyric acid concentration. In this present work we utilize independent component analysis to derive brain networks based on resting-state functional magnetic resonance imaging and use those derived networks to build a disease state classifier using machine learning (support-vector machine). We show that it is possible to achieve over 71% accuracy for disease state classification. These results are promising for the development of a clinically relevant disease state classifier. Future inclusion of other MR modalities such as high-resolution structural imaging, DTI and MRS should improve this overall accuracy.

A primer on brain-machine interfaces, concepts, and technology: a key element in the future of functional neurorestoration

Conventionally, the practice of neurosurgery has been characterized by the removal of pathology, congenital or acquired. The emerging complement to the removal of pathology is surgery for the specific purpose of restoration of function. Advents in neuroscience, technology, and the understanding of neural circuitry are creating opportunities to intervene in disease processes in a reparative manner, thereby advancing toward the long-sought-after concept of neurorestoration. Approaching the issue of neurorestoration from a biomedical engineering perspective is the rapidly growing arena of implantable devices. Implantable devices are becoming more common in medicine and are making significant advancements to improve a patient's functional outcome. Devices such as deep brain stimulators, vagus nerve stimulators, and spinal cord stimulators are now becoming more commonplace in neurosurgery as we utilize our understanding of the nervous system to interpret neural activity and restore function. One of the most exciting prospects in neurosurgery is the technologically driven field of brain-machine interface, also known as brain-computer interface, or neuroprosthetics. The successful development of this technology will have far-reaching implications for patients suffering from a great number of diseases, including but not limited to spinal cord injury, paralysis, stroke, or loss of limb. This article provides an overview of the issues related to neurorestoration using implantable devices with a specific focus on brain-machine interface technology.

Diagnostic accuracy using diffusion tensor imaging in the diagnosis of ALS: a meta-analysis

RATIONALE AND OBJECTIVES

A number of studies have reported decreases in fractional anistropy (FA) in amyotrophic lateral sclerosis using diffusion tensor imaging (DTI). The purpose of this study was to perform a meta-analysis in order to estimate the diagnostic test accuracy measures of DTI for the diagnosis of amyotrophic lateral sclerosis (ALS).

MATERIALS AND METHODS

We searched MEDLINE (1966-April 2011), EMBASE (1999-April 2011), CINAHL (1999-April 2011), and Cochrane (2005-April 2011) databases to identify studies that measured FA in ALS subjects. Human, single-center studies using a DTI region of interest (ROI) or tractography techniques were used to compare FA values along the brain corticospinal tracts between ALS subjects and healthy controls. There were no language restrictions. Independent extraction of articles by 2 authors using predefined data fields including study quality indicators. We identified 30 case-control studies that used region of interest or tractography DTI techniques. We applied binormal receiver operative characteristic (ROC) curve analysis to assign specificity and sensitivity for each study. We applied the bivariate mixed-effects regression model using the Markov Chain Monte Carlo Simulation to calculate summary estimates for the sensitivity and specificity. We used the metan module in Stata, version 11.0, to calculate the area under the ROC curve, diagnostic odds ratio and the test effectiveness summary estimates.

RESULTS

The pooled sensitivity was 0.65 (95% CI 0.61-0.69); the pooled specificity, 0.67 (95% CI 0.63-0.72); the pooled diagnostic odds ratio, 1.88 (95% CI 1.46-2.30); the pooled test effectiveness, 1.04 (95% CI 0.81-1.27); and the pooled area under the ROC curve, 0.76 (95% CI 0.71-0.81). Subanalyses comparing magnetic resonance imaging (MRI) field strength (1.5T vs. 3.0T) and brain location (corticospinal tract average vs. internal capsule) revealed no significant differences in the test accuracy measures. Reference standard used for the diagnosis of ALS was the El Escorial criteria. There was at least moderate heterogeneity between the studies. True study quality is uncertain.

CONCLUSION

The discriminatory capability of DTI to make a diagnosis of ALS is only modest. There were no significant differences in the diagnostic test accuracy summary estimates with respect to MRI field strength or brain location.

Spinal cord markers in ALS: diagnostic and biomarker considerations

Despite considerable involvement of the spinal cord in amyotrophic lateral sclerosis (ALS), current biomarker research is primarily centred on brain imaging and CSF proteomics. In clinical practice, spinal cord imaging in ALS is performed primarily to rule out alternative conditions in the diagnostic phase of the disease. Quantitative spinal cord imaging has traditionally been regarded as challenging, as it requires high spatial resolution while minimizing partial volume effects, physiological motion and susceptibility distortions. In recent years however, as acquisition and post-processing methods have been perfected, a number of exciting and promising quantitative spinal imaging and electrophysiology techniques have been developed. We performed a systematic review of the trends, methodologies, limitations and conclusions of recent spinal cord studies in ALS to explore the diagnostic and prognostic potential of spinal markers. Novel corrective techniques for quantitative spinal cord imaging are systematically reviewed. Recent findings demonstrate that imaging techniques previously used in brain imaging, such as diffusion tensor, functional and metabolic imaging can now be successfully applied to the human spinal cord. Optimized electrophysiological approaches make the non-invasive assessment of corticospinal pathways possible, and multimodal spinal techniques are likely to increase the specificity and sensitivity of proposed spinal markers. In conclusion, spinal cord imaging is an emerging area of ALS biomarker research. Novel quantitative spinal modalities have already been successfully used in ALS animal models and have the potential for development into sensitive ALS biomarkers in humans.

Enteral tube feeding for amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Enteral feeding (tube feeding) is offered to many people with amyotrophic lateral sclerosis/motor neuron disease experiencing difficulty swallowing (dysphagia) and maintaining adequate nutritional intake leading to weight loss.

OBJECTIVES

To examine the efficacy of percutaneous endoscopic gastrostomy placement or other tube feeding placement on: (1) survival;(2) nutritional status; (3) quality of life;(4) minor and major complications of percutaneous endoscopic gastrostomy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register (24 November 2009), MEDLINE (from January 1966 to September 2009), and EMBASE (from January 1980 to September 2009) for all papers on enteral tube feeding in amyotrophic lateral sclerosis/motor neuron disease. The results were screened to identify randomised controlled trials and to identify non-randomized studies that might be worthy of review and discussion. We checked references in published articles and enlisted personal communications to identify any additional references. 

SELECTION CRITERIA

A priori selection criteria included randomised and quasi-randomized controlled trials evaluating the efficacy of percutaneous endoscopic gastrostomy or other feeding tube placement. Since no such trials were discovered, all prospective and retrospective controlled studies were reviewed in the 'Background' or 'Discussion' sections of the review.

DATA COLLECTION AND ANALYSIS

We independently assessed study design and extracted data. We considered the following outcomes: (1) survival rate in months (of primary interest), (2) nutritional status measured by weight change, change in body mass index, or other quantitative index of nutritional status, (3) self-perceived quality of life and (4) safety of the procedure as indicated by minor and major complications of surgical or radiological guided PEG tube insertion. 

MAIN RESULTS

We found no randomised controlled trials comparing the efficacy of enteral tube feeding with those people who continued to eat orally, without enteral feeding. We summarized the results of retrospective and prospective studies in the 'Discussion' section.

AUTHORS' CONCLUSIONS

There are no randomised controlled trials to indicate whether enteral tube feeding is beneficial compared to continuation of oral feeding for any of the outcome measures. The 'best' evidence to date suggests a survival advantage for some people with amyotrophic lateral sclerosis/motor neuron disease, but these conclusions are tentative. Evidence for improved nutrition is also incomplete but tentatively favorable.  Quality of life has been addressed in studies and needs more attention. Based on a number of recent non-randomized studies comparing surgical and radiographic approaches to feeding tube insertion these two procedures for PEG tube insertion appear to be equivalent.

Diagnostic problems and delay of diagnosis in amyotrophic lateral sclerosis

OBJECTIVE

Initial symptoms of amyotrophic lateral sclerosis (ALS) mimic several neurological syndromes that may decelerate a correct diagnosis. The aim of our study was to investigate if diagnostic and therapeutic parameters have influence on the time of diagnosis.

METHODS

We retrospectively reviewed the medical records of 100 consecutive ALS patients focusing on clinical and diagnostic data, the timing of diagnosis and treatments attributed to the onset of symptoms of ALS.

RESULTS

Among 100 consecutive patients with ALS, 12% underwent surgery due to symptoms retrospectively attributable to ALS. The comparison of duration from first symptoms to correct diagnosis showed a significant difference between operated and non-operated patients. 35% of all ALS patients had bulbar onset symptoms. The mean time from first symptoms to diagnosis was 9 months in this group. In patients without bulbar onset it was 16.4 months which also represents a significant difference. In 44% of patients other diagnoses were considered and medically treated previous to correct diagnosis, but there was no significant delay of diagnosis.

CONCLUSION

Our study confirms that diagnosis of ALS is still a common clinical problem and shows the need of sensitive and specific diagnostic tests.

A P300-based brain-computer interface for people with amyotrophic lateral sclerosis

OBJECTIVE

The current study evaluates the efficacy of a P300-based brain-computer interface (BCI) communication device for individuals with advanced ALS.

METHODS

Participants attended to one cell of a N x N matrix while the N rows and N columns flashed randomly. Each cell of the matrix contained one character. Every flash of an attended character served as a rare event in an oddball sequence and elicited a P300 response. Classification coefficients derived using a stepwise linear discriminant function were applied to the data after each set of flashes. The character receiving the highest discriminant score was presented as feedback.

RESULTS

In Phase I, six participants used a 6 x 6 matrix on 12 separate days with a mean rate of 1.2 selections/min and mean online and offline accuracies of 62% and 82%, respectively. In Phase II, four participants used either a 6 x 6 or a 7 x 7 matrix to produce novel and spontaneous statements with a mean online rate of 2.1 selections/min and online accuracy of 79%. The amplitude and latency of the P300 remained stable over 40 weeks.

CONCLUSIONS

Participants could communicate with the P300-based BCI and performance was stable over many months.

SIGNIFICANCE

BCIs could provide an alternative communication and control technology in the daily lives of people severely disabled by ALS.

Brain metabolites in definite amyotrophic lateral sclerosis

Biomarkers beyond clinical assessment are needed in patients who suffer from amyotrophic lateral sclerosis (ALS). Here, single-voxel proton magnetic resonance spectroscopy ((1)H MRS) of the gray matter of the motor cortex and the white matter including the pyramidal tracts was used to investigate concentrations of N-acetylaspartate (NAA), creatine (Cr), choline (Cho), myoinositol, glutamate, and glutamine in patients with definite ALS in a longitudinal design (three measurements at study inclusion, after 3 and 6 months). A volume-corrected analysis of gray and white matter fractions within the volumes of interest (VOI) was performed for the identification of the absolute metabolite concentrations. The patient group showed a significant decline of the compound NAA over time in the motor cortex areas both of the clinically more and less affected hemisphere between first measurement and month 6 and for the less affected side additionally between first measurement and month 3. For the NAA/(Cr + Cho) ratio, significant decline in the less affected hemisphere was observed from the first measurement to month 3 and to month 6 as well as from month 3 to month 6. In contrast, neither NAA nor the NAA/(Cr + Cho) ratios in the white matter areas showed any significant alterations. All other compounds showed no significant changes over time. In summary, the longitudinal changes of cortical metabolite concentrations in the course of ALS could be assessed by optimized (1)H MRS techniques at group level, so that (1)H MRS parameters, in particular volume-corrected values of NAA in the clinically less affected hemisphere, seem to have the potential to serve as a surrogate marker for monitoring ALS disease progression.

Metabolic progression markers of neurodegeneration in the transgenic G93A-SOD1 mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by a progressive loss of motor neurons. Visualizing corresponding metabolic changes in the brain of patients with ALS with proton magnetic resonance spectroscopy ((1)H-MRS) may provide surrogate markers for an early disease detection, for monitoring the progression and for evaluating a treatment response. The primary objective of our study was to evaluate whether modifications in MR metabolite levels occur before clinical disease onset, and whether these changes are directly linked to a distinct spatial progression pattern in the CNS. Therefore, age-dependent alterations in the cerebral and spinal metabolic profile in the mouse model of ALS overexpressing the mutated human G93A-superoxide dismutase 1 (G93A-SOD1) were determined by high-resolution MRS of tissue extracts at 14.1 Tesla. Both non-transgenic mice (control mice) and transgenic mice overexpressing the non-mutated human SOD1 (tg-SOD1) served as controls. In the spinal cord of G93A-SOD1 mice significantly decreased levels of N-acetyl aspartate were already detected 34 days postpartum, i.e. about 60 days before the average disease onset caused by motor neuron decline. In addition, glutamine and gamma-aminobutyric acid concentrations were significantly diminished at Day 75, which is still in the presymptomatic phase of the disease. These metabolic changes were further progressive in the course of the disease and started to involve the brainstem at Day 75. Overall, high-resolution (1)H-MRS allows a sensitive spatial and temporal metabolite profiling in the presymptomatic phase of ALS even before significant neuronal cell loss occurs.

Enteral tube feeding for amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Enteral feeding (tube feeding) is offered to many people with amyotrophic lateral sclerosis/motor neuron disease experiencing difficulty swallowing (dysphagia) and maintaining adequate nutritional intake leading to weight loss.

OBJECTIVES

The aim of this review is to examine the efficacy of percutaneous endoscopic gastrostomy placement or other tube feeding placement on: (1) survival; (2) nutritional status; (3) quality of life. Another aim is to examine the minor and major complications of percutaneous endoscopic gastrostomy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register (June 2005), MEDLINE (from January 1966 to June 2005), and EMBASE (from January 1980 to June 2005) for randomized controlled trials. In addition we searched MEDLINE (January 1966 to June 2005) and EMBASE (January 1980 to June 2005) to identify non-randomized studies that might be worthy of review and discussion. We checked references in published articles, proceedings of scientific meetings, and enlisted personal communications to identify any additional references.

SELECTION CRITERIA

All randomized and quasi-randomized controlled trials were to have been selected. Since no such trials were discovered, all prospective and retrospective controlled studies were reviewed in the 'Background' or 'Discussion' sections of the review.

DATA COLLECTION AND ANALYSIS

We independently assessed study methodological design and extracted data. We considered the following outcomes: (1) survival rate in months (of primary interest), (2) nutritional status measured by weight change, change in body mass index, or other quantitative index of nutritional status, and (3) self-perceived quality of life We were also interested in reports of safety of the procedure as indicated by (4) minor and major complications of percutaneous endoscopic gastrostomy or other feeding tube placement.

MAIN RESULTS

We found no randomized controlled trials comparing the efficacy of enteral tube feeding with those people who continued to eat orally, without enteral feeding. We summarized the results of retrospective and prospective case controlled studies in the 'Discussion' section of this review.

AUTHORS' CONCLUSIONS

There are no randomized controlled trials to indicate whether enteral tube feeding is beneficial compared to continuation of oral feeding for survival. The 'best' evidence to date, based on controlled prospective cohort studies, suggests an advantage for survival in all people with amyotrophic lateral sclerosis/motor neuron disease, but these conclusions are tentative. Evidence for improved nutrition is also incomplete but tentatively favorable. Quality of life has only been addressed by a few researchers and needs more serious attention.

Evaluation of treatment effects in Alzheimer's and other neurodegenerative diseases by MRI and MRS

Neurodegeneration refers to a large clinically and pathologically heterogeneous disease entity associated with slowly progressive neuronal loss in different anatomical and functional systems of the brain. Neurodegenerative diseases often affect cognition, e.g. Alzheimer's disease (AD), dementia with Lewy bodies and vascular dementia, or different aspects of the motor system, e.g., amyotrophic lateral sclerosis, Parkinson's disease and ataxic disorders. Owing to increasing knowledge about the mechanisms leading to neurodegeneration, the development of treatments able to modify the neurodegenerative process becomes possible for the first time. Currently, clinical outcome measures are used to assess the efficacy of such treatments. However, most clinical outcome measures have a low test-retest reliability and thus considerable measurement variance. Therefore, large patient populations and long observation times are needed to detect treatment effects. Furthermore, clinical outcome measures cannot distinguish between symptomatic and disease-modifying treatment effects. Therefore, alternative biomarkers including neuroimaging may take on a more important role in this process. Because MR scanners are widely available and allow for non-invasive detection and quantification of changes in brain structure and metabolism, there is increasing interest in the use of MRI/MRS to monitor objectively treatment effects in clinical trials of neurodegenerative diseases. Particularly volumetric MRI has been used to measure atrophy rates in treatment trials of AD because the relationship between atrophic changes and neuron loss is well established and correlates well with clinical measures. More research is needed to determine the value of other MR modalities, i.e. diffusion, perfusion and functional MRI and MR spectroscopy, for clinical trials with neuroprotective drugs.

BCI Meeting 2005--workshop on clinical issues and applications

This paper describes the outcome of discussions held during the Third International BCI Meeting at a workshop charged with reviewing and evaluating the current state of and issues relevant to brain-computer interface (BCI) clinical applications. These include potential BCI users, applications, validation, getting BCIs to users, role of government and industry, plasticity, and ethics.

Global brain atrophy and corticospinal tract alterations in ALS, as investigated by voxel-based morphometry of 3-D MRI

In ALS, advanced magnetic resonance imaging (MRI) techniques are increasingly used to investigate the underlying pathology. In this study, the technique of voxel-based morphometry (VBM) was applied to 3-D MRI data in ALS patients to localize regional grey and white matter changes. Twenty-two ALS patients (mean age 58+/-9 years) with clinically definite ALS by revised El Escorial criteria were studied. None of the patients had any signs of associated frontotemporal dementia. High-resolution 3-D MRI data sets of the whole brain, collected on a 1.5 T scanner, were analysed by statistical parametric mapping (SPM) and VBM in comparison to an age-matched normal data base consisting of 22 healthy volunteers (mean age 59+/-11 years), for grey matter and white matter segments separately. Global brain atrophy was assessed by calculation of brain parenchymal fractions (BPF). In ALS patients, BPF were significantly reduced compared to controls (p = 0.0003), indicating global brain atrophy. Regional decreases of grey matter density were found in the ALS patients at corrected p<0.01 in the right-hemispheric primary motor cortex (area of the highest Z-score) and in the left medial frontal gyrus. Furthermore, regional white matter alterations were observed along the corticospinal tracts bilaterally and in multiple smaller areas including corpus callosum, cerebellum, frontal and occipital subcortical regions. Besides considerable global atrophy in ALS, the topography of ALS-associated cerebral morphological changes could be mapped using VBM, in particular white matter signal changes along the bilateral corticospinal tracts, but also in extra-motor areas. VBM might be a potential tool to visualize disease progression in future longitudinal studies.

Biomarkers of neurodegenerative disorders: how good are they?

Biomarkers are very important indicators of normal and abnormal biological processes. Specific changes in pathologies, biochemistries and genetics can give us comprehensive information regarding the nature of any particular disease. A good biomarker should be precise and reliable, distinguishable between normal and interested disease, and differential between different diseases. It is believed that biomarkers have great potential in predicting chances for diseases, aiding in early diagnosis, and setting standards for the development of new remedies to treat diseases. New technologies have enabled scientists to identify biomarkers of several different neurodegenerative diseases. The followings, for instance, are only a few of the many new biomarkers that have been recently identified: the phosphorylated tau protein and aggregated Beta-amyloid peptide for Alzheimer's disease (AD), Alpha-synuclein contained Lewy bodies and altered dopamine transporter (DAT) imaging for Parkinson's disease (PD), SOD mutations for familial amyotrophic lateral sclerosis (ALS), and CAG repeats resulted from Huntington's gene mutations in Huntington's disease (HD). This article will focus on the most-recent findings of biomarkers belonging to the four mentioned neurodegenerative diseases.

Brain-computer interfaces--the key for the conscious brain locked into a paralyzed body

Brain-computer interfaces (BCIs) are systems that allow us to translate in real-time the electrical activity of the brain in commands to control devices. They do not rely on muscular activity and can therefore provide communication and control for those who are severely paralyzed (locked-in) due to injury or disease. It has been shown that locked-in patients are able to achieve EEG-controlled cursor or limb movement and patients have successfully communicated by means of a BCI. Current BCIs differ in how the neural activity of the brain is recorded, how subjects (humans and animals) are trained to produce a specific EEG response, how the signals are translated into device commands, and which application is provided to the user. The present review focuses on approaches to BCIs that process the EEG on-line and provide EEG feedback or feedback of results to the user. We regard online processing and feedback cornerstones for routine application of BCIs in the field. Because training patients in their home environment is effortful and personal and financial resources are limited, only few studies on BCI long-term use for communication with paralyzed patients are available. The need for multidisciplinary research, comprising computer science, engineering, neuroscience, and psychology is now being acknowledged by the BCI community. A standard BCI platform, referred to as BCI2000, has been developed, which allows us to better combine and compare the different BCI approaches of different laboratories. As BCI laboratories now also join to unify their expertise and collaborations are funded, we consider it realistic that within few years we will be able to offer a BCI, which will be easy to operate for patients and caregivers.

Interrupting apoptosis in neurodegenerative disease: potential for effective therapy?

Current treatment options for neurodegenerative diseases are limited and mainly affect only the symptoms of disease. Because of the unknown and probably multiple causes of these diseases, they cannot be readily targeted. However, it has been established that apoptosis contributes to neuronal loss in most neurodegenerative diseases. A possible treatment option is to interrupt the signaling networks that link neuronal damage to apoptotic degradation in neurodegeneration. The viability of this option depends upon the extent to which apoptosis accounts for neuron loss, whether or not interruption of apoptosis signaling results in recovery of neurological function and whether or not there are significant downsides to targeting apoptosis. Several compounds acting at different sites in known apoptotic signaling networks are currently in development and a few are in clinical trial. If an apoptosis-targeted compound succeeds in slowing or halting neurological dysfunction in one or more neurodegenerative diseases, a new era in the treatment of neurodegenerative diseases will begin.

MRI detects early hindlimb muscle atrophy in Gly93Ala superoxide dismutase-1 (G93A SOD1) transgenic mice, an animal model of familial amyotrophic lateral sclerosis

MRI has been used to measure hindlimb muscle volume in female and male transgenic mice overexpressing the Gly93Ala (G93A) mutant human superoxide dismutase 1 (SOD1), a widely used model of familial amyotrophic lateral sclerosis (FALS), over the first 4 months of life. Significant decreases in the hindlimb muscle volume of the female G93A SOD1 mice were evident from 11 weeks of age, before other overt pathology appeared. By 15 weeks volume had decreased by 37% compared with 7 weeks, from 0.84+/-0.04 cm(3) (mean+/-standard deviation, n = 6) to 0.54+/-0.07 cm(3), (p < 0.05), despite an increase in body weight of ca. 12% (from 16.2 +/- 1.4 to 18.1 +/- 0.7 g). Female wild-type volume increased by ca. 30% whilst the body weight increased by 15%. Muscle wasteage was less (0.82+/-0.1 to 0.65+/-0.02 cm(3), p < 0.05, n = 6) in male G93A SOD1 mice between 8 and 16 weeks of age, against a body weight increase trend from 20.7 +/- 0.4 to 21.6 +/- 0.5 g, (p > 0.05). Wild-type male muscle volume did not change significantly over this period, with an increase in body weight of 20%. Longitudinal MRI hindlimb muscle volume measurements may provide a straightforward, rapid, non-invasive and sensitive, way of monitoring outcome of experimental ALS treatments.

Amyotrophic lateral sclerosis and primary lateral sclerosis: evidence-based diagnostic evaluation of the upper motor neuron

Magnetic resonance imaging and MR spectroscopy are important tools in the diagnostic evaluation of patients with suspected motor neuron disease. Further investigation is needed to determine and to compare the utility of various neuroimaging markers for diagnosis and disease progression [112]. Newer MR tools, such as diffusion tensor imaging, magnetization transfer imaging, and functional MR imaging, have substantial promise as scientific and clinical tools in this ongoing endeavor.

The diagnostic utility of FLAIR imaging in clinically verified amyotrophic lateral sclerosis

PURPOSE

To explore the overall diagnostic ability of magnetic resonance (MR) fluid-attenuated inversion recovery (FLAIR) imaging for clinically verified amyotrophic lateral sclerosis (ALS).

MATERIALS AND METHODS

Abnormal signal intensity in FLAIR images of 18 patients with ALS and 18 age-matched normal controls were scored and compared. Six patients had serial MR imaging scans within 97 days. Mann Whitney U statistics and ANOVA were used for statistical analysis.

RESULTS

Hyperintensity in the subcortical white matter (SWM) and the dark line along the posterior rim of the precentral gyri were found more frequently in patients with ALS. The scores for these two signs were significantly different from those of normal controls. Hyperintensity in the corticospinal tract (CST) was found in both ALS and normal controls, but the difference was not statistically significant. ANOVA on the serial FLAIR studies revealed no significant difference in the scores among the series. The hyperintensity in SWM had a sensitivity of 56% and specificity of 94%, while the dark line in the motor cortex had a 74% sensitivity and 67% specificity.

CONCLUSION

Hyperintensity in SWM and the dark line along the posterior rim of the precentral gyri appeared more frequently in the patients with ALS. SWM hyperintensity has a better specificity in association with clinically verified ALS, while the motor dark line has a better sensitivity. No correlation was found between the FLAIR findings and progression of the disease.

Amyotrophic lateral sclerosis: progress and prospects for treatment

Fifteen years ago, a role for excitotoxic damage in the pathology of amyotrophic lateral sclerosis (ALS) was postulated. This stimulated the development of riluzole, the only available treatment for the disease. Since then, the identification of abnormal forms of superoxide dismutase as the genetic basis of certain familial forms of ALS has provided a huge impetus to the search for new effective treatments for this devastating disease. Transgenic mouse models have been developed expressing these aberrant mutants that develop a form of motor neurone disease the progress of which can be slowed by riluzole. Studies in these mice have provided evidence for a role for excitotoxic, apoptotic and oxidative processes in the development of pathology. The mice can be used for testing molecules targeting these processes as potential therapies, to allow the most promising to be evaluated in humans. Several such agents are currently in clinical trials. Many previous clinical trials in ALS were insufficiently powered to demonstrate any relevant effect on disease progression. This situation has been to some extent remedied in the more recent trials, which have recruited many hundreds of patients. However, with the exception of studies with riluzole, the results of these have been disappointing. In particular, a number of large trials with neurotrophic agents have revealed no evidence for efficacy. Nonetheless, the need for large multinational trials of long duration limits the number that can be carried out and makes important demands on investment. For this reason, surrogate markers that can be used for rapid screening in patients of potential treatments identified in the transgenic mice are urgently needed.