Laryngeal Sensitivity in Patients with Amyotrophic Lateral Sclerosis

Identification of corneal and intra-epidermal axonal swellings in amyotrophic lateral sclerosis

INTRODUCTION/AIMS

In patients with amyotrophic lateral sclerosis (ALS), axonal spheroids in motor axons have been identified in post-mortem studies. In this study, axonal spheroids and swellings on C-fibers of ALS patients were investigated using corneal confocal microscopy (CCM) and skin biopsy, respectively.

METHODS

Thirty-one ALS patients and 20 healthy subjects were evaluated with CCM to assess corneal nerve-fiber length (CNFL), -fiber density (CNFD), -branch density (CNBD), dendritic cell (DC) density, and axonal spheroids originating from C-fibers (>100 μm2 ). In addition, intraepidermal nerve fiber density (IENFD) and axonal swellings (>1.5 μm) were assessed in skin biopsies obtained from the arms and legs of 22 patients and 17 controls.

RESULTS

In ALS patients, IENFD, CNFD, CNFL, and CNBD were not different from controls. The density of DCs and the number of patients with increased DC density were higher in ALS patients than controls (p = .0005 and p = .008). The number of patients with axonal spheroids was higher than controls (p = .03).

DISCUSSION

Evaluation of DCs and axonal bulbs in C-fibers of ALS patients could provide insights into pathophysiology or potentially serve as biomarkers in ALS.

Assessment of the Sensitivity of the Vocal Tract in Parkinson Disease by Nasal Video Endoscopy

Introduction  Sensory deficits of the upper airways are common in people with Parkinson disease. Compounded by considerable deterioration of the swallowing function, these deficits may contribute to the elevated rates of morbidity and mortality among this population. Objective  To examine the sensitivity of the vocal tracts of people with Parkinson disease using nasal videoendoscopy and to compare the results with paired controls. Methods  The present was a prospective, observational, case-control study. Sensitivity assessments were conducted in a sample of 24 people divided into 2 groups: one group of 12 patients with Parkinson's disease, and a control group with 12 healthy subjects. The study group also underwent a fiberoptic endoscopic evaluation of swallowing and answered the Swallowing Disturbance Questionnaire (SQD) to detect dysphagia. Results  There was a significant difference ( p  < 0.05) in the region of the arytenoid cartilages, showing that sensitivity was better preserved among the control group, and that sensitivity deficits were present in the study group. The qualitative results showed sensorial impairment in the study group than in the control group regarding the base of the tongue, the vestibular folds, and the vocal folds. The study group showed self-awareness regarding the deficits in the swallowing function, but there was no statistically significant association between swallowing function deficits and deterioration of sensorial function among them. Conclusions  Sensorial deficits were present in the study group when compared to the healthy subjects, mainly in the qualitative evaluation.

Sensitivity and specificity of the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised to detect dysarthria in individuals with amyotrophic lateral sclerosis

INTRODUCTION/AIMS

Given the widespread use of the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) to measure disease progression in ALS and recent reports demonstrating its poor sensitivity, we aimed to determine the sensitivity and specificity of the ALSFRS-R bulbar subscale and speech item to detect validated clinical ratings of dysarthria in individuals with ALS.

METHODS

Paired ALSFRS-R and validated Speech Intelligibility Test (SIT) data from individuals with ALS were analyzed. Trained raters completed duplicate, independent, and blinded ratings of audio recordings to obtain speech intelligibility (%) and speaking rate (words per minute, WPM). Binary dysarthria profiles were derived (dysarthria ≤96% intelligible and/or <150 WPM). Data were obtained using the Kruskal-Wallis test, receiver-operating characteristic (ROC) curve, area under the curve (AUC), sensitivity and specificity percentages, and positive/negative predictive values (PPV/NPV).

RESULTS

A total of 250 paired SIT and ALSFRS-R data points were analyzed. Dysarthria was confirmed in 72.4% (n = 181). Dysarthric speakers demonstrated lower ALSFRS-R bulbar subscale (8.9 vs. 11.2) and speech item (2.7 vs. 3.7) scores (P < .0001). The ALSFRS-R bulbar subscale score had an AUC of 0.81 (95% confidence interval [CI] 0.75 to 0.86). A subscale score of ≤11 yielded a sensitivity of 86%, specificity of 57%, PPV of 84%, and NPV of 60% to correctly identify dysarthria status. The ALSFRS-R speech item score demonstrated an AUC of 0.81 to detect dysarthria (95% CI 0.76 to 0.85), with sensitivity of 79%, specificity of 75%, PPV of 89%, and NPV of 58% for a speech item cutpoint of ≤3.

DISCUSSION

The ALSFRS-R bulbar and speech item subscale scores may be useful, inexpensive, and quick tools for monitoring dysarthria status in ALS.

Healthy Human Laryngopharyngeal Sensory Innervation Density Correlates with Age

OBJECTIVE

Somatosensory feedback from upper airway structures is essential for swallowing and airway defense but little is known about the identities and distributions of human upper airway neurons. Furthermore, whether sensory innervation modifies with aging is unknown. In this study, we quantify neuronal and chemosensory cell density in upper airway structures and correlate with age.

METHODS

Participants underwent biopsies from base of tongue, lateral and midline pharyngeal wall, epiglottis, and arytenoids (N = 25 13 female/12 male; 20-80 years, mean 51.4 years without clinical diagnosis of dysphagia or clinical indication for biopsy). Tissue sections were labeled with antibodies for all neurons, myelinated neurons, and chemosensory cells. Densities of lamina propria innervation, epithelial innervation, solitary chemosensory cells, and taste buds were calculated and correlated with age.

RESULTS

Arytenoid had the highest density of innervation and chemosensory cells across all measures compared to other sites. Taste buds were frequently observed in arytenoid and epiglottis. Base of tongue, lateral pharynx, and midline posterior pharynx had minimal innervation and few chemosensory cells. Epithelial innervation was present primarily in close proximity to chemosensory cells and taste buds. Overall innervation and myelinated fibers in the arytenoid lamina propria decline with aging.

CONCLUSION

Findings establish the architecture of healthy adult sensory innervation and demonstrate the varied distribution of laryngopharyngeal innervation, necessary steps toward understanding the sensory basis for swallowing and airway defense. We also document age-related decline in arytenoid innervation density. These findings suggest that sensory afferent denervation of the upper airway may be a contributing factor to presbyphagia.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:773-784, 2023.

Ultrasonographic and manometric study of the tongue as biomarkers of dysphagia in patients with amyotrophic lateral sclerosis

BACKGROUND

The possibility of having methods to assess dysphagia in amyotrophic lateral sclerosis (ALS) patients in a minimally invasive manner could facilitate follow-up and allow performing of therapeutic interventions at earlier stages of the disease. The aim of the study was to analyze the role of tongue strength and thickness in ALS patients and their correlation with dysphagia and bulbar function.

METHODS

A sample of outpatients with ALS was evaluated for demographic and clinical features. Tongue thickness and strength have been measured for each patient, and quantitative and qualitative data of the videofluoroscopy swallow study have been analyzed.

RESULTS

Of the 38 ALS patients studied, 47.4% were women, and 26.3% had bulbar onset. The median time between symptom onset and the study was 24 months (IQR 11.5-48), and 55.3% of the patients were carriers of non-invasive mechanical ventilation. Tongue strength identified patients with impaired oral and pharyngeal transit and those with bolus residue scale (BRS) > 1 or penetration-aspiration scale (PAS) ≥ 3. In contrast, tongue thickness is only associated with impaired oral transit. Finally, anterior tongue strength ≤ 34 kPa and posterior tongue strength ≤ 34.5 kPa detected ALS penetrators/aspirators (PAS ≥ 3) and patients with ALS with post-swallow residue (BRS > 1).

CONCLUSIONS

Our results suggest that measures that assess the functionality (strength) of the tongue are more valuable than morphological measurements (thickness) for the follow-up of patients with ALS. Alterations of the anterior and posterior lingual strength correlate with the presence of bronchoaspiration and post-swallowing residue (BRS > 1).

Safety and Clinical Benefits of Laryngeal Closure in Patients with Amyotrophic Lateral Sclerosis

This study evaluated the safety of laryngeal closure and post-surgical changes in swallowing function of patients with amyotrophic lateral sclerosis (ALS) and proposed an appropriate surgical strategy for patients with ALS. Clinical and surgical data of 26 consecutive patients with ALS who underwent laryngeal closure at Nagoya University Hospital in Japan between 2003 and 2020 were retrospectively analyzed. Changes in swallowing functions were evaluated before and approximately 1 month post-surgery using Neuromuscular Disease Swallowing Status Scale (NdSSS), and Functional Oral Intake Scale (FOIS). The median operation time was 126 min (range, 51-163 min), and the median intraoperative blood loss was 20 mL (range, 0-88 mL). Among the 26 ALS patients who underwent laryngeal closure, grade 1 (mild) complications occurred in three patients (12%); however, no severe complications were observed. After surgery, 25 patients (96%) maintained the swallowing function and only one patient (4%) had deteriorating NdSSS and FOIS scores. No patients were referred to our hospital due to severe aspiration pneumonia after the surgery. Two patients did not require a feeding tube after the surgery and returned to oral intake. Laryngeal closure may be a safe surgical procedure for preventing chronic aspiration and may also maintain swallowing function of patients with ALS. Further multicenter prospective studies using the gold standard videofluoroscopic swallowing examination are required to support our findings.

Profiles of Dysarthria and Dysphagia in Individuals With Amyotrophic Lateral Sclerosis

PURPOSE

While dysarthria and dysphagia are known bulbar manifestations of amyotrophic lateral sclerosis (ALS), the relative prevalence of speech and swallowing impairments and whether these bulbar symptoms emerge at the same time point or progress at similar rates is not yet clear. We, therefore, sought to determine the relative prevalence of speech and swallowing impairments in a cohort of individuals with ALS and to determine the impact of disease duration, severity, and onset type on bulbar impairments.

METHOD

Eighty-eight individuals with a confirmed diagnosis of ALS completed the ALS Functional Rating Scale-Revised (ALSFRS-R), underwent videofluoroscopy (VF), and completed the Sentence Intelligibility Test (SIT) during a single visit. Demographic variables including disease duration and onset type were also obtained from participants. Duplicate, independent, and blinded ratings were completed using the Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) scale and SIT to index dysphagia (DIGEST ≥ 1) and dysarthria (< 96% intelligible and/or < 150 words per minute) status. Descriptive statistics, Pearson chi-squared tests, independent-samples t tests, and odds ratios were performed.

RESULTS

Dysphagia and dysarthria were instrumentally confirmed in 68% and 78% of individuals with ALS, respectively. Dysarthria and dysphagia were associated (p = .01), and bulbar impairment profile distributions in rank order included (a) dysphagia - dysarthria (59%, n = 52), (b) no dysphagia - dysarthria (19%, n = 17), (c) no dysphagia - no dysarthria (13%, n = 11), and (d) dysphagia - no dysarthria (9%, n = 8). Participants with dysphagia or dysarthria demonstrated 4.2 higher odds of exhibiting a bulbar impairment in the other domain than participants with normal speech and swallowing (95% CI [1.5, 12.2]). There were no differences in ALSFRS-R total scores or disease duration across bulbar impairment profiles (p > .05). ALSFRS-R bulbar subscale scores were significantly lower in individuals with dysphagia versus no dysphagia (8.4 vs. 10.4, p < .0001) and dysarthria versus no dysarthria (8.5 vs. 10.9, p < .0001). Dysphagia and onset type (p = .003) and dysarthria and onset type were associated (p < .0001).

CONCLUSIONS

Over half of the individuals with ALS in this study demonstrated both dysphagia and dysarthria. Of those with only one bulbar impairment, speech was twice as likely to be the first bulbar symptom to degrade. Future studies are needed to confirm these findings and determine the longitudinal progression of bulbar impairments in this patient population.

Sensory Involvement in Amyotrophic Lateral Sclerosis

Although amyotrophic lateral sclerosis (ALS) is pre-eminently a motor disease, the existence of non-motor manifestations, including sensory involvement, has been described in the last few years. Although from a clinical perspective, sensory symptoms are overshadowed by their motor manifestations, this does not mean that their pathological significance is not relevant. In this review, we have made an extensive description of the involvement of sensory and autonomic systems described to date in ALS, from clinical, neurophysiological, neuroimaging, neuropathological, functional, and molecular perspectives.

Discriminant Ability of the Eating Assessment Tool-10 to Detect Swallowing Safety and Efficiency Impairments

OBJECTIVES/HYPOTHESIS

Quick, sensitive dysphagia screening tools are necessary to identify high-risk patients for further evaluation in busy multidisciplinary amyotrophic lateral sclerosis (ALS) clinics. We examined the relationship between self-perceived dysphagia using the validated Eating Assessment Tool-10 (EAT-10) and videofluoroscopic analysis of swallowing safety and efficiency.

STUDY DESIGN

Prospective, observational, longitudinal study.

METHODS

Individuals with ALS completed the EAT-10 and a videofluoroscopic swallowing study. Duplicate, independent, blinded analyses of the validated Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) scale were performed to index swallowing safety and efficiency (mild dysphagia: DIGEST ≥ 1, moderate dysphagia: DIGEST ≥ 2). A between-groups analysis of variance with Games-Howell test for post-hoc pairwise comparisons was performed to examine EAT-10 scores across dysphagia severity levels. Receiver operator characteristic curve analysis, area under the curve (AUC), sensitivity, specificity, positive-negative predictive values (PPV, NPV), and odds ratios (OR) were derived.

RESULTS

Four hundred and thirty five paired EAT-10 and DIGEST scores were analyzed. Mean EAT-10 score was 8.48 (95% confidence interval [CI]: 7.63-9.33). Individuals with dysphagia demonstrated higher EAT-10 scores (mild: 4.1 vs. 11.3, moderate: 6.0 vs. 17.5, P < .001). Mean EAT-10 scores increased across DIGEST levels (D0: 4.1, D1: 7.9, D2: 15.1, D3: 20.4, D4: 39.0). For mild dysphagia, an EAT-10 cut score of 3 was optimal: AUC 0.74 (95% CI: 0.69-0.78; sensitivity: 77%; specificity: 53%; PPV: 71%; NPV: 60%; OR: 3.5). An EAT-10 cut score of 7 optimized detection of moderate dysphagia: AUC 0.83 (95% CI: 0.78-0.87; sensitivity: 81%; specificity: 66%; PPV: 39%; NPV: 93%; OR: 8.1).

CONCLUSION

The EAT-10 is an easy-to-administer dysphagia screening tool with good discriminant ability for use in ALS clinics.

LEVEL OF EVIDENCE

2 Laryngoscope, 132:2319-2326, 2022.

Pilot Study of Respiratory-Swallow Coordination in Amyotrophic Lateral Sclerosis

PURPOSE

Amyotrophic lateral sclerosis (ALS) impacts bulbar and respiratory musculature, which may contribute to impaired swallow function (dysphagia) and respiratory-swallow coordination. The purpose of this pilot study was to examine if respiratory-swallow coordination in individuals with ALS was perturbed compared to healthy controls. We further explored relationships between measures of respiratory function and self-reported swallowing outcomes on respiratory-swallow coordination.

METHOD

We employed a cross-sectional design with eight participants with ALS and eight age- and sex-matched healthy participants. Respiratory inductance plethysmography and a nasal cannula were used to capture respiratory-swallow phase patterns during a standardized clinical swallow examination. The advantageous respiratory-swallow phase pattern was defined if exhalation surrounded the swallow (E-E). Spirometry was used to capture indices of respiratory function (forced vital capacity % predicted, peak cough flow [PCF]). Validated questionnaires were used to collect information regarding ALS-related bulbar functional status and swallowing-related concerns.

RESULTS

Compared to the matched healthy cohort, individuals with ALS demonstrated higher rates of non-E-E respiratory-swallow phase patterning and worse bulbar/swallow dysfunction. Group (ALS), swallow tasks, and PCF were significantly associated with respiratory-swallow phase pattern.

CONCLUSIONS

These preliminary findings support altered respiratory-swallow phase patterning in ALS. Future work should employ an instrumental assessment to quantify swallowing physiology and elucidate the relationship between perturbed respiratory-swallow coordination and swallowing function.

Discriminant ability of the 3-ounce water swallow test to detect aspiration in amyotrophic lateral sclerosis

BACKGROUND

Given the need for quick and accurate dysphagia screening tools to optimize referral workflows and resource utilization in fast-paced multidisciplinary amyotrophic lateral sclerosis (ALS) clinics, we evaluated the discriminant ability of the 3 oz. water swallow test (WST) to detect aspiration in individuals with ALS.

METHODS

A total of 212 paired 3 oz. WST (index test) and standardized videofluoroscopic swallow studies (reference test) were completed in individuals with a confirmed diagnosis of ALS. Blinded raters analyzed swallowing safety using the validated penetration-aspiration scale (PAS; non-aspirator: PAS < 6; aspirator: PAS ≥ 6). Receiver operating characteristic curve analysis, area under the curve (AUC), sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were calculated.

KEY RESULTS

Index test: 78 (36.8%) WSTs were scored as a fail and 134 (63.2%) as a pass.

REFERENCE TEST

Aspiration was confirmed in 67 (31.6%) reference tests with 145 (68.4%) reference tests verified as having no aspiration. Sensitivity and specificity of the 3 oz. WST to detect radiographically confirmed aspiration was 55.2% and 71.7%, respectively (AUC: 0.635, PPV: 47.4%, NPV: 77.6%).

CONCLUSIONS & INFERENCES

In this dataset, the 3 oz. WST did not demonstrate adequate sensitivity or specificity to detect aspiration in people with ALS as a stand-alone dysphagia screening tool.

Effects of Skin Stimulation on Sensory-Motor Networks Excitability: Possible Implications for Physical Training in Amyotrophic Lateral Sclerosis

Background

Many different trials were assessed for rehabilitation of patients with amyotrophic lateral sclerosis (ALS), with non-unique results. Beside the effects on muscle trophism, some of the encouraging results of physical training could be ascribed to the modulation of cortical excitability, which was found hyperexcited in ALS.

Objective

The effects of tactile skin stimulation in the modulation of the sensory-motor integrative networks in healthy subjects were assayed through the paired associative stimulation (PAS) protocol.

Methods

In total, 15 healthy subjects were enrolled. In the standard PAS session, the average amplitude of the motor evoked potential (MEP) after 10 stimuli of transcranial magnetic stimulation (TMS) was measured at the baseline and after the PAS protocol (0, 10, 20, 30, and 60 min). In the skin stimulation session, the average amplitude of the MEP was measured before and after 10 min of skin stimulation over the hand. Subsequently, each subject underwent the PAS stimulation and the measure of the average amplitude of the MEP (0, 10, 20, 30, and 60 min).

Results

The tactile skin stimulation on healthy subjects increases the PAS-induced sensory-motor network hyperexcitability in healthy subjects.

Conclusion

Skin stimulation should be avoided in the physiotherapeutic approaches for patients with ALS, given the possible hyperexciting effects on the already upmodulated sensory-motor networks. They can be taken into account for diseases characterized by downregulation of cortical and transcortical networks.

Validation of the DYALS (dysphagia in amyotrophic lateral sclerosis) questionnaire for the evaluation of dysphagia in ALS patients

BACKGROUND

Dysphagia is a common symptom during the trajectory of ALS, and it can significantly impact on the quality of life and prognosis of patients. Nowadays, no specific tool for the screening of dysphagia in ALS is validated, and the approach is heterogeneous across the Italian centres.

OBJECTIVE

To validate the DYALS (dysphagia in amyotrophic lateral sclerosis) questionnaire, adapting the DYMUS (dysphagia in multiple sclerosis) questionnaire, for the assessment of dysphagia in ALS patients, in order to uniform the evaluations across the Italian ALS network.

METHODS

We included 197 patients diagnosed with ALS following the El Escorial criteria, in sixteen Italian ALS centres between 1st December 2019 and 1st July 2020. For each patient, we collected clinical and demographic data and obtained ALSFRS-r score, ALSAQ-5 score, DYMUS score, and EAT-10 score.

RESULTS

Across the 197 patients, the ratio M/F was 113/84, and the median age was 64 years (IQR 56-72.5). Bulbar patients were 20%, and spinal patients 80%. The median ALSFRSr total score of patients was 35 (IQR 28-39). DYALS score was statistically higher in bulbar ALS than in spinal ALS (median = 6, IQR 4.5-9 vs median = 1, IQR 0-5, z = 6.253, p < 0.0001). DYALS questionnaire showed a high internal consistency (Cronbach's alpha = 0.88). There was a statistically significant correlation between DYALS and EAT-10 (rho = 0.90, p < 0.0001).

CONCLUSIONS

DYALS scale is reliable, manageable, and easily usable for the screening of dysphagia in ALS. It can be shared with all the Italian ALS centres in order to collect uniform data for therapeutic strategies and clinical trials.

Progression of Oropharyngeal Dysphagia in Amyotrophic Lateral Sclerosis: A Retrospective Cohort Study

Little is known regarding the optimal timing of dysphagia assessment and PEG indication in amyotrophic lateral sclerosis (ALS). The study aims to investigate the progression of dysphagia in a cohort of ALS patients and to analyse whether there are variables linked to a faster progression of dysphagia and faster indication of PEG placement. A retrospective cohort study in 108 individuals with ALS. Fiberoptic endoscopic evaluation of swallowing was performed 6 monthly until PEG indication or death. Dysphagia severity and PEG indication were assessed using Penetration Aspiration Scale. Progression Index (PI) analysed the risk of disease progression (fast/slow) in relation to dysphagia onset and PEG indication. Patients were grouped based on ALS onset and PI. Person-time incidence rates were computed considering dysphagia onset and PEG indication from ALS symptoms during the entire observation period and have been reported as monthly and 6-month rates. Cox regression survival analysis assessed dysphagia and PEG risk factors depending on onset. Person-time incidence rates of dysphagia progression and PEG risk were increased based on type of ALS onset and PI. Patients with a fast progressing disease and with bulbar onset (BO) show statistically significant increased risk of dysphagia (BO 178.10% hazard ratio (HR) = 2.781 P < 0.01; fast 181.10% HR 2.811 P < 0.01). Regarding PEG risk, fast patients and patients with BO had a statistically significant increased risk (fast 147.40% HR 2.474 P < 0.01, BO 165.40% HR 2.654 P < 0.01). Fast PI predicts the likelihood of faster progression of dysphagia and PEG indication and should be included in multidisciplinary assessments and considered in the design of future guidelines regarding dysphagia management in ALS patients.

Level of Evidence Level IV.

Upper Airway Assessment and Responses During Mechanically Assisted Cough

When the ability to cough is impaired, secretion clearance may be assisted and augmented with mechanical insufflation-exsufflation (MI-E). In some individuals, the efficacy of MI-E may be hampered by counterproductive upper airway reactions, where the airways close in response to positive pressures. To fully utilize the therapeutic potential inherent in the MI-E technology, we need a better understanding of the pathophysiology behind these untoward reactions. There is increasing interest in monitoring and measuring upper airway responses to MI-E and how such information can be used to optimize MI-E settings. The purpose of this narrative review is to increase the theoretical understanding of the larynx as a respiratory organ, summarize the current literature in the area, and provide insight into how this knowledge can affect current clinical practice.

A novel hypothesis on metal dyshomeostasis and mitochondrial dysfunction in amyotrophic lateral sclerosis: Potential pathogenetic mechanism and therapeutic implications

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by motor dysfunctions resulting from the loss of upper (UMNs) and lower (LMNs) motor neurons. While ALS symptoms are coincidental with pathological changes in LMNs and UMNs, the causal relationship between the two is unclear. For example, research on the extra-motor symptoms associated with this condition suggests that an imbalance of metals, including copper, zinc, iron, and manganese, is initially induced in the sensory ganglia due to a malfunction of metal binding proteins and transporters. It is proposed that the resultant metal dyshomeostasis may promote mitochondrial dysfunction in the satellite glial cells of these sensory ganglia, causing sensory neuron disturbances and sensory symptoms. Sensory neuron hyperactivation can result in LMN impairments, while metal dyshomeostasis in spinal cord and brain stem parenchyma induces mitochondrial dysfunction in LMNs and UMNs. These events could prompt intracellular calcium dyshomeostasis, pathological TDP-43 formation, and reactive microglia with neuroinflammation, which in turn activate the apoptosis signaling pathways within the LMNs and UMNs. Our model suggests that the degeneration of LMNs and UMNs is incidental to the metal-induced changes in the spinal cord and brain stem. Over time psychiatric symptoms may appear as the metal dyshomeostasis and mitochondrial dysfunction affect other brain regions, including the reticular formation, hippocampus, and prefrontal cortex. It is proposed that metal dyshomeostasis in combination with mitochondrial dysfunction could be the underlying mechanism responsible for the initiation and progression of the pathological changes associated with both the motor and extra-motor symptoms of ALS.

Riluzole Oral Suspension: Bioavailability Following Percutaneous Gastrostomy Tube-modeled Administration Versus Direct Oral Administration

PURPOSE

During amyotrophic lateral sclerosis progression, up to 85% of patients develop dysphagia. Riluzole oral suspension 50 mg/10 mL is bioequivalent to riluzole 50-mg film-coated tablets administered orally under fasting conditions. Here, we compare the bioavailability of a single 50-mg dose of riluzole oral suspension via intragastric tube, a proxy for percutaneous endoscopic gastrostomy administration, with that of oral administration in healthy volunteers under fasting conditions. Secondary objectives included the plasma pharmacokinetic and safety profiles of each administration route.

METHODS

This was a single-center, single-dose, open-label, randomized, 2-period, 2-sequence, crossover bioequivalence/bioavailability study. Healthy volunteers were randomized to riluzole oral suspension 50 mg/10 mL either via nasogastric tube or orally, with a 5-day washout before crossover.

FINDINGS

A total of 32 subjects were randomized (safety population); 30 were eligible for pharmacokinetic analysis. The ratios (nasogastric tube/oral) of the geometric least squares means and the geometric 90% CIs of AUC_0-t, AUC_0-inf, and C_max were calculated to be 90.60% (85.66%-95.82%), 90.43% (85.47%-95.67%), and 96.99% (89.40%-105.23%), respectively, indicating bioequivalence. No significant differences in C_max, T_max, K_el, and t_1/2el between treatments were found. Overall, riluzole oral suspension was well tolerated. No deaths or other serious adverse events were reported.

IMPLICATIONS

In this study, riluzole oral suspension was bioequivalent when administered intragastrically and orally in healthy subjects under fasting conditions. Both administration methods were well tolerated. These results show that intragastric administration of riluzole oral suspension may provide an important formulation option in people with amyotrophic lateral sclerosis who have a percutaneous endoscopic gastrostomy tube.