Diagnosis and treatment of bulbar symptoms in amyotrophic lateral sclerosis

Validation of Clinical Observations of Mastication in Persons with ALS

Amyotrophic lateral sclerosis (ALS) is a progressive neurological disease that can result in difficulties with mastication leading to malnutrition, choking or aspiration, and reduced quality of life. When evaluating mastication, clinicians primarily observe spatial and temporal aspects of jaw motion. The reliability and validity of clinical observations for detecting jaw movement abnormalities is unknown. The purpose of this study is to determine the reliability and validity of clinician-based ratings of chewing performance in neuro-typical controls and persons with varying degrees of chewing impairments due to ALS. Adults chewed a solid food consistency while full-face video were recorded along with jaw kinematic data using a 3D optical motion capture system. Five experienced speech-language pathologists watched the videos and rated the spatial and temporal aspects of chewing performance. The jaw kinematic data served as the gold-standard for validating the clinicians' ratings. Results showed that the clinician-based rating of temporal aspects of chewing performance had strong inter-rater reliability and correlated well with comparable kinematic measures. In contrast, the reliability of rating the spatial and spatiotemporal aspects of chewing (i.e., range of motion of the jaw, consistency of the chewing pattern) was mixed. Specifically, ratings of range of motion were at best only moderately reliable. Ratings of chewing movement consistency were reliable but only weakly correlated with comparable measures of jaw kinematics. These findings suggest that clinician ratings of temporal aspects of chewing are appropriate for clinical use, whereas ratings of the spatial and spatiotemporal aspects of chewing may not be reliable or valid.

Voluntary Cough Airflow Differentiates Safe Versus Unsafe Swallowing in Amyotrophic Lateral Sclerosis

Dysphagia and aspiration are prevalent in amyotrophic lateral sclerosis (ALS) and contribute to malnutrition, aspiration pneumonia, and death. Early detection of at risk individuals is critical to ensure maintenance of safe oral intake and optimal pulmonary function. We therefore aimed to determine the discriminant ability of voluntary cough airflow measures in detecting penetration/aspiration status in ALS patients. Seventy individuals with ALS (El-Escorial criteria) completed voluntary cough spirometry testing and underwent a standardized videofluoroscopic swallowing evaluation (VFSE). A rater blinded to aspiration status derived six objective measures of voluntary cough airflow and evaluated airway safety using the penetration-aspiration scale (PAS). A between groups ANOVA (safe vs. unsafe swallowers) was conducted and sensitivity, specificity, area under the curve (AUC) and likelihood ratios were calculated. VFSE analysis revealed 24 penetrator/aspirators (PAS ≥3) and 46 non-penetrator/aspirators (PAS ≤2). Cough volume acceleration (CVA), peak expiratory flow rise time (PEFRT), and peak expiratory flow rate (PEFR) were significantly different between airway safety groups (p < 0.05) and demonstrated significant discriminant ability to detect the presence of penetration/aspiration with AUC values of: 0.85, 0.81, and 0.78, respectively. CVA <45.28 L/s/s, PEFR <3.97 L/s, and PEFRT >76 ms had sensitivities of 91.3, 82.6, and 73.9 %, respectively, and specificities of 82.2, 73.9, and 78.3 % for identifying ALS penetrator/aspirators. Voluntary cough airflow measures identified ALS patients at risk for penetration/aspiration and may be a valuable screening tool with high clinical utility.

Discriminant ability of the Eating Assessment Tool-10 to detect aspiration in individuals with amyotrophic lateral sclerosis

BACKGROUND

Oropharyngeal dysphagia is prevalent in individuals with amyotrophic lateral sclerosis (ALS) leading to malnutrition, aspiration pneumonia, and death. These factors necessitate early detection of at-risk patients to prolong maintenance of safe oral intake and pulmonary function. This study aimed to evaluate the discriminant ability of the Eating Assessment Tool (EAT-10) to identify ALS patients with unsafe airway protection during swallowing.

METHODS

Seventy ALS patients completed the EAT-10 survey and underwent a standardized videofluoroscopic evaluation of swallowing. Two blinded raters determined airway safety using the Penetration Aspiration Scale (PAS). A between groups anova (safe vs penetrators vs aspirators) was conducted and sensitivity, specificity, area under the curve (AUC), and likelihood ratios calculated.

KEY RESULTS

Mean EAT-10 scores for safe swallowers, penetrators, and aspirators (SEM) were: 4.28 (0.79) vs 7.10 (1.79) vs 20.50 (3.19), respectively, with significant differences noted for aspirators vs safe swallowers and aspirators vs penetrators (p < 0.001). The EAT-10 demonstrated good discriminant ability to accurately identify ALS penetrator/aspirators (PAS ≥3) with a cut off score of 3 (AUC: 0.77, sensitivity: 88%, specificity: 57%). The EAT-10 demonstrated excellent accuracy at identifying aspirators (PAS ≥6) utilizing a cut off score of 8 (AUC: 0.88, sensitivity: 86%, specificity: 72%, likelihood ratio: 3.1, negative predictive value: 95.5%).

CONCLUSIONS & INFERENCES

The EAT-10 differentiated safe vs unsafe swallowing in ALS patients. This patient self-report scale could represent a quick and meaningful aide to dysphagia screening in busy ALS clinics for the identification and referral of dysphagic patients for further instrumental evaluation.

[Age-related changes in swallowing. Physiology and pathophysiology]

The term presbyphagia refers to all changes of swallowing physiology that are manifested with increasing age. Alterations in the pattern of deglutition that are part of healthy aging are called primary presbyphagia. Primary presbyphagia is not an illness in itself but contributes to a more pervasive naturally diminished functional reserve, making older adults more susceptible to dysphagia. If disorders in swallowing occur in the elderly as a comorbidity of a specific disease, for example stroke or neurodegenerative disorders, this is called secondary presbyphagia. Increasing age has an impact on each stage of deglutition. In the oral preparatory phase a diminished input for smell and taste as well as a usually multifactorial cause of dry mouth are the most important influencing factors. Sarcopenia, the degenerative loss of skeletal muscle mass, strength and quality associated with aging, interferes in particular with the oropharyngeal phase. A decreased sensory feedback from the oropharyngeal mucosa leads to a delayed triggering of the swallowing reflex. Finally, a reduction in connective tissue elasticity and changes of the axial skeleton lead to various modifications of the swallowing pattern with advanced age.

A comprehensive review of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a late-onset fatal neurodegenerative disease affecting motor neurons with an incidence of about 1/100,000. Most ALS cases are sporadic, but 5–10% of the cases are familial ALS. Both sporadic and familial ALS (FALS) are associated with degeneration of cortical and spinal motor neurons. The etiology of ALS remains unknown. However, mutations of superoxide dismutase 1 have been known as the most common cause of FALS. In this study, we provide a comprehensive review of ALS. We cover all aspects of the disease including epidemiology, comorbidities, environmental risk factor, molecular mechanism, genetic factors, symptoms, diagnostic, treatment, and even the available supplement and management of ALS. This will provide the reader with an advantage of receiving a broad range of information about the disease.

Symptom Management and End-of-Life Care in Amyotrophic Lateral Sclerosis

The number of available symptomatic treatments has markedly enhanced the care of patients with amyotrophic lateral sclerosis (ALS). Once thought to be untreatable, patients with ALS today clearly benefit from multidisciplinary care. The impact of such care on the disease course, including rate of progression and mortality, has surpassed the treatment effects commonly sought in clinical drug trials. Unfortunately, there are few randomized controlled trials of medications or interventions addressing symptom management. In this review, the authors provide the level of evidence, when available, for each intervention that is currently considered standard of care by consensus opinion.

Discriminant ability of the Eating Assessment Tool-10 to detect aspiration in individuals with amyotrophic lateral sclerosis

BACKGROUND

Oropharyngeal dysphagia is prevalent in individuals with amyotrophic lateral sclerosis (ALS) leading to malnutrition, aspiration pneumonia, and death. These factors necessitate early detection of at-risk patients to prolong maintenance of safe oral intake and pulmonary function. This study aimed to evaluate the discriminant ability of the Eating Assessment Tool (EAT-10) to identify ALS patients with unsafe airway protection during swallowing.

METHODS

Seventy ALS patients completed the EAT-10 survey and underwent a standardized videofluoroscopic evaluation of swallowing. Two blinded raters determined airway safety using the Penetration Aspiration Scale (PAS). A between groups anova (safe vs penetrators vs aspirators) was conducted and sensitivity, specificity, area under the curve (AUC), and likelihood ratios calculated.

KEY RESULTS

Mean EAT-10 scores for safe swallowers, penetrators, and aspirators (SEM) were: 4.28 (0.79) vs 7.10 (1.79) vs 20.50 (3.19), respectively, with significant differences noted for aspirators vs safe swallowers and aspirators vs penetrators (p < 0.001). The EAT-10 demonstrated good discriminant ability to accurately identify ALS penetrator/aspirators (PAS ≥3) with a cut off score of 3 (AUC: 0.77, sensitivity: 88%, specificity: 57%). The EAT-10 demonstrated excellent accuracy at identifying aspirators (PAS ≥6) utilizing a cut off score of 8 (AUC: 0.88, sensitivity: 86%, specificity: 72%, likelihood ratio: 3.1, negative predictive value: 95.5%).

CONCLUSIONS & INFERENCES

The EAT-10 differentiated safe vs unsafe swallowing in ALS patients. This patient self-report scale could represent a quick and meaningful aide to dysphagia screening in busy ALS clinics for the identification and referral of dysphagic patients for further instrumental evaluation.

Is There a Role for Exercise in the Management of Bulbar Dysfunction in Amyotrophic Lateral Sclerosis?

PURPOSE

The role of exercise in the management of people with amyotrophic lateral sclerosis (PALS) is controversial and currently unclear. The purpose of this review article is to review literature examining the impact of limb, respiratory, and oral motor exercise on function, disease progression, and survival in PALS and the transgenic ALS animal model.

METHOD

A literature review was conducted to examine relevant studies published in peer-reviewed journals between 1960 and 2014. All studies were appraised for quality of research and were assigned a level of evidence, and treatment outcomes were classified as either positive, negative, or neutral.

RESULTS

A total of 18 exercise-based intervention studies on limb (13), respiratory (3), or speech (2) function were identified. Of the human clinical trials, 6 were experimental and 4 were exploratory. No experimental studies were identified examining the impact of targeted exercise on speech or swallowing function. Mild to moderate intensity limb or respiratory exercise, applied early in the disease, was noted to have a beneficial impact on motor function and survival.

CONCLUSION

Insufficient data exist to support or refute the role of exercise in the management of bulbar dysfunction in PALS. This represents a critical area of future investigation.

Louis EK. Neuromuscular disorders and sleep in critically ill patients

Sleep-disordered breathing (SDB) is a frequent presenting manifestation of neuromuscular disorders and can lead to significant morbidity and mortality. If not recognized and addressed early in the clinical course, SDB can lead to clinical deterioration with respiratory failure. The pathophysiologic basis of SDB in neuromuscular disorders, clinical features encountered in specific neuromuscular diseases, and diagnostic and management strategies for SDB in neuromuscular patients in the critical care setting are reviewed. Noninvasive positive pressure ventilation has been a crucial advance in critical care management, improving sleep quality and often preventing or delaying mechanical ventilation and improving survival in neuromuscular patients.

Predicting Early Bulbar Decline in Amyotrophic Lateral Sclerosis: A Speech Subsystem Approach

Purpose. To develop a predictive model of speech loss in persons with amyotrophic lateral sclerosis (ALS) based on measures of respiratory, phonatory, articulatory, and resonatory functions that were selected using a data-mining approach. Method. Physiologic speech subsystem (respiratory, phonatory, articulatory, and resonatory) functions were evaluated longitudinally in 66 individuals with ALS using multiple instrumentation approaches including acoustic, aerodynamic, nasometeric, and kinematic. The instrumental measures of the subsystem functions were subjected to a principal component analysis and linear mixed effects models to derive a set of comprehensive predictors of bulbar dysfunction. These subsystem predictors were subjected to a Kaplan-Meier analysis to estimate the time until speech loss. Results. For a majority of participants, speech subsystem decline was detectible prior to declines in speech intelligibility and speaking rate. Among all subsystems, the articulatory and phonatory predictors were most responsive to early bulbar deterioration; and the resonatory and respiratory predictors were as responsive to bulbar decline as was speaking rate. Conclusions. The articulatory and phonatory predictors are sensitive indicators of early bulbar decline due to ALS, which has implications for predicting disease onset and progression and clinical management of ALS.

Supporting communication for patients with neurodegenerative disease

BACKGROUND

Communication supports, referred to as augmentative and alternative communication (AAC), are an integral part of medical speech-language pathology practice, yet many providers remain unfamiliar with assessment and intervention principles. For patients with complex communication impairments secondary to neurodegenerative disease, AAC services differ depending on whether their condition primarily affects speech and motor skills (ALS), language (primary progressive aphasia) or cognition (Alzheimer's disease). This review discusses symptom management for these three conditions, identifying behavioral strategies, low- and high-tech solutions for implementation during the natural course of disease. These AAC principles apply to all neurodegenerative diseases in which common symptoms appear.

OBJECTIVES

To present AAC interventions for patients with neurodegenerative diseases affecting speech, motor, language and cognitive domains. Three themes emerge: (1) timing of intervention: early referral, regular re-evaluations and continual treatment are essential; (2) communication partners must be included from the onset to establish AAC acceptance and use; and (3) strategies will change over time and use multiple modalities to capitalize on patients' strengths.

CONCLUSIONS

AAC should be standard practice for adults with neurodegenerative disease. Patients can maintain effective, functional communication with AAC supports. Individualized communication systems can be implemented ensuring patients remain active participants in daily activities.

Oxidative stress and autophagic alteration in brainstem of SOD1-G93A mouse model of ALS

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurodegenerative disease involving both upper and lower motor neurons. The mechanism of motor neuron degeneration is still unknown. Although many studies have been performed on spinal motor neurons, few have been reported on brainstem and its motor nuclei. The aim of this study was to investigate oxidative stress and autophagic changes in the brainstem and representative motor nuclei of superoxide dismutase 1 (SOD1)-G93A mouse model of ALS. The expression levels of cluster of differentiation molecule 11b (CD11b), glial fibrillary acidic protein, glutamate-cysteine ligase catalytic subunit, heme oxygenase-1, NAD(P)H: quinone oxidoreductase 1, voltage-dependent anion-selective channel protein 1, Sequestosome 1/p62 (p62), microtubule-associated protein 1 light chain 3B (LC3), and SOD1 proteins in brainstem were examined by Western blot analysis. Immunohistochemistry and immunofluorescence were performed to identify the cellular localization of SOD1, p62, and LC3B, respectively. The results showed that there were progressive asctrocytic proliferation and microglial activation, induction of antioxidant proteins, and increased p62 and LC3II expression in brainstem of SOD1-G93A mice. Additionally, SOD1 and p62 accumulated in hypoglossal, facial, and red nuclei, but not in oculomotor nucleus. Furthermore, electron microscope showed increased autophagic vacuoles in affected brainstem motor nuclei. Our results indicate that brainstem share similar gliosis, oxidative stress, and autophagic changes as the spinal cord in SOD1-G93A mice. Thus, SOD1 accumulation in astrocytes and neurons, oxidative stress, and altered autophagy are involved in motor neuron degeneration in the brainstem, similar to the motor neurons in spinal cord. Therefore, therapeutic trials in the SOD1G93A mice need to target the brainstem in addition to the spinal cord.

Dysphagia in amyotrophic lateral sclerosis: prevalence and clinical findings

OBJECTIVES

To characterize swallowing deficits in amyotrophic lateral sclerosis (ALS); investigate the delay in dysphagia onset; estimate correlations between dysphagia severity and patients' functional status; identify the symptom(s) most likely to predict dysphagia.

MATERIALS AND METHODS

A group of 49 consecutive patients with ALS, 14 with bulbar onset and 35 with spinal onset, underwent swallowing evaluation including bedside and fiberoptic endoscopic examination to detect dysphagia.

RESULTS

Patients with dysphagia were more likely than those without to have bulbar onset ALS (P = 0.02); more severely impaired chewing (P = 0.01); and tongue muscle deficits (P = 0.001). The only variable measured at first examination significantly associated with dysphagia was a more than mild tongue muscle deficit. The only variable useful in predicting dysphagia was a chewing deficit. In 10 of the 49 patients studied, swallowing evaluation disclosed an impaired cough reflex.

CONCLUSIONS

Dysphagia in patients with ALS correlates significantly with bulbar onset and with oral swallowing impairment. Fiberoptic swallowing evaluation is a useful tool for detecting swallowing deficits and laryngeal sensitivity in patients with ALS. An impaired cough reflex is an unexpected finding in many patients with ALS.

Acute stimulation of transplanted neurons improves motoneuron survival, axon growth, and muscle reinnervation

Few options exist for treatment of pervasive motoneuron death after spinal cord injury or in neurodegenerative diseases such as amyotrophic lateral sclerosis. Local transplantation of embryonic motoneurons into an axotomized peripheral nerve is a promising approach to arrest the atrophy of denervated muscles; however, muscle reinnervation is limited by poor motoneuron survival. The aim of the present study was to test whether acute electrical stimulation of transplanted embryonic neurons promotes motoneuron survival, axon growth, and muscle reinnervation. The sciatic nerve of adult Fischer rats was transected to mimic the widespread denervation seen after disease or injury. Acutely dissociated rat embryonic ventral spinal cord cells were transplanted into the distal tibial nerve stump as a neuron source for muscle reinnervation. Immediately post-transplantation, the cells were stimulated at 20 Hz for 1 h. Other groups were used to control for the cell transplantation and stimulation. When neurons were stimulated acutely, there were significantly more neurons, including cholinergic neurons, 10 weeks after transplantation. This led to enhanced numbers of myelinated axons, reinnervation of more muscle fibers, and more medial and lateral gastrocnemius muscles were functionally connected to the transplant. Reinnervation reduced muscle atrophy significantly. These data support the concept that electrical stimulation rescues transplanted motoneurons and facilitates muscle reinnervation.

Pre- and postsynaptic mechanisms underlying inhibition of hypoglossal motor neuron excitability by riluzole

Riluzole is the sole treatment for amyotrophic lateral sclerosis (ALS), but its therapeutically relevant actions on motor neurons are not well defined. Whole cell patch-clamp recordings were made from hypoglossal motor neurons (HMs, n = 25) in brain stem slices from 10- to 23-day-old rats anesthetized with pentobarbital sodium to investigate the hypothesis that riluzole inhibits HMs by multiple mechanisms. Riluzole (20 μM) hyperpolarized HMs by decreasing an inward current, inhibited voltage-gated persistent Na(+) and Ca(2+) currents activated by slow voltage ramps, and negatively shifted activation of the hyperpolarization-activated cationic current (IH). Repetitive firing of HMs was strongly inhibited by riluzole, which also increased action potential threshold voltage and rheobase and decreased amplitude and maximum rise slope but did not alter the maximal afterhyperpolarization amplitude or decay time constant. HM rheobase was inversely correlated with persistent Na(+) current density. Glutamatergic synaptic transmission was inhibited by riluzole by both pre- and postsynaptic effects. Riluzole decreased activity-dependent glutamate release, as shown by decreased amplitude of evoked and spontaneous excitatory postsynaptic currents (EPSCs), decreased paired-pulse ratio, and decreased spontaneous, but not miniature, EPSC frequency. However, riluzole also decreased miniature EPSC amplitude and the inward current evoked by local application of glutamate onto HMs, suggesting a reduction of postsynaptic glutamate receptor sensitivity. Riluzole thus has a marked inhibitory effect on HM activity by membrane hyperpolarization, decreasing firing and inhibiting glutamatergic excitation by both pre- and postsynaptic mechanisms. These results broaden the range of mechanisms controlling motor neuron inhibition by riluzole and are relevant to researchers and clinicians interested in understanding ALS pathogenesis and treatment.

Ventilatory control in ALS

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to "fight back" via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients.

Assessment of swallowing in motor neuron disease and Asidan/SCA36 patients with new methods

BACKGROUND

We report on a unique complication of cerebellar ataxia and motor neuron disease named Asidan/SCA36 with a high frequency of tongue atrophy. We aimed to elucidate dysphagia in amyotrophic lateral sclerosis (ALS) and spinal, bulbar muscular atrophy (SBMA), and Asidan/SCA36 patients with new methods.

METHODS

Patients diagnosed with ALS (n=20), SBMA (n=6), and Asidan (n=12) were included. A videofluoroscopic swallow study (VFS), an assessment of maximal tongue pressure (MTP), and impedance pharyngography (IPG) were applied.

RESULTS

The frequencies of VFS abnormalities were 70%, 50%, and 33% in ALS, SBMA, and Asidan/SCA36, respectively. Compared with control subjects (31.6 ± 6.3 kPa, mean ± SD), MTP was significantly decreased in ALS patients and SBMA patients, but was relatively preserved in Asidan patients. ALS patients performed more swallowing actions (Ns) detected by IPG than did control subjects, but SBMA and Asidan/SCA36 patients performed similar Ns to control subjects.

CONCLUSIONS

VFS showed a higher frequency of swallowing abnormalities in ALS patients. MTP and IPG measurements showed the most severe involvement in ALS patients and a relatively preserved swallowing function in SBMA and Asidan/SCA36 patients.

Riluzole

Amyotrophic lateral sclerosis (Lou Gehrig’s disease) is a devastating neurodegenerative disorder for which the only licensed treatment is riluzole. Although riluzole clinical efficacy is rather limited, its use has important implications for identifying those parameters that might improve its clinical benefits (dose, timing, disease stage) and for its off-label administration in other neurodegenerative diseases, such as spinal cord injury. Studies of riluzole also have an intrinsically heuristic value to unveil mechanisms regulating the excitability of brain and spinal neurons because this drug is a pharmacological tool to probe the function of certain ion channels, or to study neurotransmitter release processes, and intracellular neuroprotective pathways. The present review focuses on how riluzole acts on brain and spinal neurons within motor networks, what mechanisms can be deduced from its effects, and what conditions may favor its use to contrast neurodegeneration or to ameliorate late symptoms like spasticity. Taking as an example the experimental neurodegeneration caused by overactivation of glutamatergic synapses (excitotoxicity), it seems likely that protection of motor networks by riluzole involves selected administration timing and dosing to target processes for releasing glutamate from very active synapses or for dampening repetitive firing by hyperfunctional motor cells.

Search for compensation postures with videofluoromanometric investigation in dysphagic patients affected by amyotrophic lateral sclerosis

PURPOSE

This study was undertaken to verify the effectiveness of compensatory postures, suggested on the basis of the type of dysphagia identified at videofluoromanometric (VFM) investigation to ensure safe oropharyngeal transit.

MATERIALS AND METHODS

Eighty-one patients with amyotrophic lateral sclerosis (ALS) underwent speech therapy assessment and VFM investigation of the swallowing process. In the event of altered transit, penetration or aspiration of contrast material into the airways, compensation postures for correction of the swallowing disorder were suggested and verified during VFM examination.

RESULTS

In 37 patients, contrast agent transport was preserved and safe; in 19, we observed penetration of the contrast agent into the laryngeal inlet without aspiration; in 24, there was aspiration (four preswallowing, eight intraswallowing, nine postswallowing, three mixed), whereas in one patient no transit was seen. Penetration without aspiration was resolved by coughing or throat clearing; aspiration was resolved in 13 patients by assuming the chin-tuck posture and in six by rotating the head; in five patients, it was not resolved. A hyperextended head posture proved to be effective to resolve lack of transit.

CONCLUSIONS

By correlating morphological with functional data, VFM enables one not only to precisely characterise the dysphagic disorder but also to identify the most appropriate compensation posture for each patient and verify its effectiveness.

Respiratory motoneurons and pathological conditions: lessons from hypoglossal motoneurons challenged by excitotoxic or oxidative stress

Hypoglossal motoneurons (HMs) are respiration-related brainstem neurons that command rhythmic contraction of the tongue muscles in concert with the respiratory drive. In experimental conditions, HMs can exhibit a range of rhythmic patterns that may subserve different motor outputs and functions. Neurodegenerative diseases like amyotrophic lateral sclerosis (ALS; Lou-Gehrig disease) often damage HMs with distressing symptoms like dysarthria, dysphagia and breathing difficulty related to degeneration of respiratory motoneurons. While the cause of ALS remains unclear, early diagnosis remains an important goal for potential treatment because fully blown clinical symptoms appear with degeneration of about 30% motoneurons. Using a simple in vitro model of the rat brainstem to study the consequences of excitotoxicity or oxidative stress (believed to occur during the onset of ALS) on HMs, it is possible to observe distinct electrophysiological effects associated with HM experimental pathology. In fact, excitotoxicity caused by glutamate uptake block triggers sustained bursting and enhanced synaptic transmission, whereas oxidative stress generates slow depolarization, augmented repeated firing, and decreased synaptic transmission. In either case, only a subpopulation of HMs shows abnormal functional changes. Although these two insults induce separate functional signatures, the consequences on HMs after a few hours are similar and are preceded by activation of the stress transcription factor ATF-3. The deleterious action of excitotoxicity is inhibited by early administration of riluzole, a drug currently employed for the symptomatic treatment of ALS, demonstrating that this in vitro model can be useful for testing potential neuroprotective agents.

Energy metabolism in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is characterised by the progressive degeneration of upper and lower motor neurons. Besides motor neuron degeneration, ALS is associated with several defects in energy metabolism, including weight loss, hypermetabolism, and hyperlipidaemia. Most of these abnormalities correlate with duration of survival, and available clinical evidence supports a negative contribution of defective energy metabolism to the overall pathogenic process. Findings from animal models of ALS support this view and provide insights into the underlying mechanisms. Altogether, these results have clinical consequences for the management of defective energy metabolism in patients with ALS and pave the way for future therapeutic interventions.

A case of amyotrophic lateral sclerosis presented as oropharyngeal Dysphagia

Amyotrophic lateral sclerosis is a rare disease. It is a fatal neurodegenerative disease characterized by progressive muscular paralysis reflecting degeneration of motor neurons which leads to muscle weakness and muscle wasting. Respiratory failure limits survival to 2-5 years after disease onset. Several clinical manifestations including dysphagia can result in reductions in both the quality of life and life expectancy. Dysphagia occurs at onset in about one third of case, although generally it occurs in later stage of the disease. Evaluation of dysphagia includes video-fluoroscopic swallow study, radiological esophagogram, flexible endoscopic examination, ultrasound examination, conventional manometry and electromyography. We report a case of amyotrophic lateral sclerosis in a 54-year-old man presenting oropharyngeal dysphagia which was diagnosed by high resolution esophageal manometry presenting abnormality of the upper esophageal sphincter.

Transient oxidative stress evokes early changes in the functional properties of neonatal rat hypoglossal motoneurons in vitro

Oxidative stress of motoneurons is believed to be an important contributor to neurodegeneration underlying the familial (and perhaps even the sporadic) form of amyotrophic lateral sclerosis (ALS). This concept has generated numerous rodent genetic models with inborn oxidative stress to mimic the clinical condition. ALS is, however, a predominantly sporadic disorder probably triggered by environmental causes. Thus, it is interesting to understand how wild-type motoneurons react to strong oxidative stress as this response might cast light on the presymptomatic disease stage. The present study used, as a model, hypoglossal motoneurons from the rat brainstem slice to investigate how hydrogen peroxide could affect synaptic transmission and intrinsic motoneuron excitability in relation to their survival. Hydrogen peroxide (1 mm; 30 min) induced inward current or membrane depolarization accompanied by an increase in input resistance, enhanced firing and depressed spontaneous synaptic events. Despite enhanced intracellular oxidative processes, there was no death of motoneurons, although most cells were immunopositive for activating transcription factor 3, a stress-related transcription factor. Voltage-clamp experiments indicated increased frequency of excitatory or inhibitory miniature events, and reduced voltage-gated persistent currents of motoneurons. The global effect of this transient oxidative challenge was to depress the input flow from the premotor interneurons to motoneurons that became more excitable due to a combination of enhanced input resistance and impaired spike afterhyperpolarization. Our data show previously unreported changes in motoneuron activity associated with cell distress caused by a transient oxidative insult.

Amyotrophic lateral sclerosis: sonographic evaluation of dysphagia

PURPOSE

The authors sought to determine the role of video ultrasonography (VUS) in the diagnostic assessment of dysphagia in patients with amyotrophic lateral sclerosis (ALS).

MATERIALS AND METHODS

Nine patients underwent simultaneous static and dynamic VUS examination and videofluoroscopy (VFS) of swallowing.

RESULTS

At the static phase, VUS showed 5/9 patients had lingual atrophy. Abnormal bolus position was observed in 6/9 patients at VUS and 3/9 at VFS. Both techniques identified an inability to keep the bolus in the oral cavity in 4/9 patients. At the dynamic phase, reduced lingual movement was observed in 5/9 patients at VUS and 2/9 at VFS. Disorganised tongue movement was seen in 3/9 patients at VUS and in 2/9 at VFS. Fragmented swallowing was only visualised at VUS. Stagnation of ingested material was never visualised at VUS, whereas it was clearly depicted in 2/9 patients at VFS.

CONCLUSIONS

VUS can be integrated into the diagnostic protocol for evaluating swallowing in patients with ALS, as it has higher sensitivity than VFS in assessing the dynamic factors that represent the early signs of dysphagia.

A systematic study of brainstem motor nuclei in a mouse model of ALS, the effects of lithium

Transgenic mice expressing the human superoxide dismutase 1 (SOD-1) mutant at position 93 (G93A) develop a phenotype resembling amyotrophic lateral sclerosis (ALS). In fact, G93A mice develop progressive motor deficits which finally lead to motor palsy and death. This is due to the progressive degeneration of motor neurons in the ventral horn of the spinal cord. Although a similar loss is reported for specific cranial motor nuclei, only a few studies so far investigated degeneration in a few brainstem nuclei. We recently reported that chronic lithium administration delays onset and duration of the disease, while reducing degeneration of spinal motor neuron. In the present study, we extended this investigation to all somatic motor nuclei of the brain stem in the G93A mice and we evaluated whether analogous protective effects induced by lithium in the spinal cord were present at the brain stem level. We found that all motor but the oculomotor nuclei were markedly degenerated in G93A mice, and chronic treatment with lithium significantly attenuated neurodegeneration in the trigeminal, facial, ambiguus, and hypoglossal nuclei. Moreover, in the hypoglossal nucleus, we found that recurrent collaterals were markedly lost in G93A mice while they were rescued by chronic lithium administration.