Amyotrophic Lateral Sclerosis: A Cross-sectional Survey on Sialorrhoea

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterised by the degeneration of both upper motor neurons in the primary motor cortex and lower motor neurons in the brainstem and spinal cord. Even though there is worldwide variation, the global prevalence of ALS is estimated to be 6/1,00,000 population.^[1] The profile of ALS is different in India when compared to the Western population.^[2] It is a relatively uncommon disease in India with a prevalence of about 3–5/100,000 population.^[3] When compared to the Western population, where the average age of onset is between 55 and 65 years, Indians have an average age of onset of one or two decades earlier.^[4]

ALS is primarily characterised by motor symptoms, including muscular weakness and spasticity. Progressive muscle involvement and increasing disabilities are the hallmark of ALS. Even though ALS can have a spinal or bulbar onset, both symptoms usually become apparent as the disease progresses. In spinal onset ALS, the symptoms primarily include muscle weakness of the limbs and spasticity; whereas in bulbar onset ALS, the marked symptoms are dysphagia and speech impairment. ALS is also characterised by non-motor symptoms, including neuropsychiatric, autonomic, gastrointestinal and vascular manifestations.^[5] Sialorrhoea in ALS can be considered a motor or non-motor symptom.^[5] Sialorrhoea in ALS is primarily attributed to tongue spasticity, orofacial muscle weakness and palatolingual muscle dysfunction. Impaired coordination of these muscle groups leads to pooling of saliva in the anterior portion of the mouth. Ultimately, this neuromuscular incoordination hampers the initiation of the swallowing reflex, further obstructing the normal transit of saliva from the oral cavity to the oropharynx.^[6]

Autonomic impairment is also involved in the pathophysiology of sialorrhoea in ALS.^[7] Increased saliva flow rates are observed in patients with ALS.^[8] However, it is thought to be of very low significance in the causation of sialorrhoea when compared to the bulbar weakness.

Regardless of its underlying cause, drooling presents significant challenges, resulting in clinical and functional complications such as social impairment, including embarrassment and isolation, as well as increased risks of aspiration, skin breakdown, malodour and infection.^[9] Such complications can severely diminish the quality of life in individuals living with ALS.^[8] In ALS patients who require non-invasive ventilation (NIV), the time taken to achieve a satisfactory NIV adaptation is significantly affected by sialorrhoea.^[10] Currently, several effective treatment options are available for problematic drooling in ALS, including external beam radiation therapy.^[11] Determining the extent of the problem related to drooling among ALS patients is crucial for determining the need and urgency of targeted management strategies.

While several studies have examined the prevalence of sialorrhoea in ALS, the results have varied considerably across reports.^[12] This may be attributable to differences in methodologies, estimation approaches, and populations studied. An earlier report from India involved very few patients.^[13] Hence, a cross-sectional survey was undertaken to estimate the prevalence and severity of sialorrhoea in a larger cohort of ALS patients. We also intended to study the current management choices of problematic salivation issues, which can help in future studies.

MATERIALS AND METHODS

RESULTS

During the 4-month study period, a total of 76 ALS patients were included in the neuro-palliative registry. Follow-up was attempted for all participants; however, six could not be contacted via telephone. Hence, a consecutive sample of 70 patients who consented to the study was included. The mean age of the cohort was 51.8 (SD 12.8) years, and it ranged from 25 to 84 years. The majority of them (74.3%) were male. Most of the patients (71.4%) were living in South Indian states. The demographic profile is presented in Table 1.

The duration of illness ranged from 4 to 72 months, with a mean of 21.6 (SD 15.7). The duration since confirmatory diagnosis of ALS ranged from 1 month to 55 months, with a mean of 12.2 (SD 12.3). The clinical profile of the patients is presented in Table 2.

A total of 28 patients (40%) reported some degree of drooling or saliva-related impairment. Of these, 15 patients (21.4%) experienced mild drooling, 9 (12.9%) had moderate symptoms, while 2 patients each (2.9%) reported severe and profuse drooling, respectively. None of the patients were using any home remedies to reduce salivation.

On exploring the impact of sialorrhoea on patients, caregivers and visitors, the respondents mentioned that they had gotten used to the drooling. None of the respondents mentioned that drooling was an issue, which made the family or the visitors feel uncomfortable. They mentioned that even though the symptom is bothersome, they were used to dealing with it. The prevalence of sialorrhoea among the patients is presented in Figure 1.

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Figure 1:

Prevalence of sialorrhoea among amyotrophic lateral sclerosis patients.

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The association of demographic and clinical variables with the severity of sialorrhoea is presented in Table 3. Compared to patients with limb-onset presentation, patients with bulbar-onset ALS experienced a significantly higher degree of sialorrhoea (P = 0.008). Sialorrhoea among ALS patients by onset type is presented in Figure 2.

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Figure 2:

Sialorrhoea among amyotrophic lateral sclerosis patients by onset type.

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Pearson correlation analysis revealed a positive association between duration of illness and severity of sialorrhoea (r = 0.30, P = 0. 012).

DISCUSSION

ALS is characterised by a range of debilitating motor and non-motor symptoms. In addition to prominent motor impairments such as muscle weakness, frequent falls and spasticity, extra-motor symptoms such as drooling can also contribute significantly to patient distress. As symptomatic management remains the cornerstone of ALS care, understanding the burden of sialorrhoea is essential. This study was therefore undertaken to examine the extent of drooling-related problems among patients with ALS in India. The profile of ALS patients observed in this survey is very similar to the previous reports. The cohort consisted mostly of younger patients, with the majority of them between 40 and 60 years of age. A quarter of them were aged <40 years. A study by Sondhi et al., describing the profile of patients with ALS from Western states of India, reported the mean age to be 53 years.^[2] In comparison to the global picture, Indian patients are considered to be younger at the age of onset of illness.^[18]

With regard to the site of onset, most of the patients (80%) had limb onset disease. In studies from various countries, there is an overall predominance of limb onset ALS when compared to bulbar onset ALS, with reports ranging from 58 to 82%.^[19]

The mean duration of illness among the patients in this study was 21.6 months. The majority of the patients were in the 1^st year after the disease onset. Other studies from India also report a mean duration of illness as 17.7^[4] and 19.2 months,^[2] which are higher than Western reports.

In this study, the problem of salivation was found in 40% of the patients. Studies from various countries have reported varying prevalence of sialorrhoea in patients with ALS, ranging from 20% to 44.2%.^[12] A pooled prevalence of 30.8% was observed in a meta-analysis that involved 17 studies across the globe.^[12] A clinic-based study in India found that 52% of the ALS patients had sialorrhoea.^[20] The study also reported that 40% of the patients had severe or profuse drooling. On the contrary, in the current study, we found that only a quarter of the patients had moderate-to-severe symptoms. Correspondingly, a meta-analysis also reported that 21.7% of the patients had moderate-to-severe symptoms.^[12]

A higher proportion of patients with bulbar-onset ALS exhibited sialorrhoea in this study, with greater severity observed in this group as well. Bulbar onset has also been identified as a significant predictor of sialorrhoea in previous research.^[20,21] The disease pathology involving the bulbar muscles and the resultant weakness explains this. Age and gender were not found to be factors associated with sialorrhoea. This finding was concurrent with other studies.^[21] In the present study, we observed that the longer the duration of the illness, the more severe the symptoms of salivation. This corresponds with the natural progression of the illness and can be explained by the increasing weakness related to it.

It is worth noting that, on exploration during the telephone interviews, none of the caregivers mentioned drooling as a cause of major distress for them or the visitors of the patient. While this study did not employ a formal qualitative methodology, the researchers incorporated informal observations and spontaneous discussions with patients and caregivers during interactions. These insights, though not systematically collected, are reflected in the narrative description. Even though they mentioned drooling to be bothersome, the weakness and disability predominated the conversations. Drooling was another symptom among the multiple other problems that the family caregivers were battling. This highlights the need for awareness among treating teams about the distressing symptoms that need to be screened among patients who need palliative care. It also points to the fact that patients or caregivers may not always bring up their symptoms for discussion unless they are very highly concerned about them. However, given the availability of choices in treatment for these symptoms, clinicians may need to address them as part of the routine evaluation of these patients. It is acknowledged that issues such as aspiration risks, hygiene challenges and the overall discomfort associated with sialorrhoea warrant deeper exploration. Future research using structured qualitative methods^[22] could provide a more comprehensive understanding of caregiver and patient experiences.

In the present study, only a quarter of patients who had problems related to salivation were on anticholinergic drugs. A study conducted in the UK showed that 52.7% of the patients who had complaints related to excess salivation received pharmacological management.^[21] The low rates of treatment observed in this study could be due to several factors, such as overshadowing of the issue of salivation by more severe complaints, clinician hesitancy, side effects of drugs and lack of awareness among patients and caregivers that excessive salivation is potentially treatable. This needs further exploration. The most common drugs used for excess salivation among the patients included glycopyrrolate and amitriptyline. In the UK, the most commonly used medications were hyoscine, amitriptyline, carbocisteine, glycopyrrolate and atropine.^[21]

This study brings attention to sialorrhoea, an often underrecognised yet distressing symptom in patients with ALS. Our findings highlight the differing prevalence based on onset type, suggesting the need for heightened clinical vigilance, particularly in those with bulbar onset. In addition, while our study emphasises prevalence, we recognise that integration of routine screening and management strategies into standard palliative care protocols remains an important, yet currently underdeveloped area.^[23,24] Addressing this gap could significantly improve symptom control and overall patient comfort. Future studies should assess the effectiveness of medications, botulinum toxin and non-pharmacological approaches for sialorrhoea.

CONCLUSION

Sialorrhoea is a common and often distressing symptom for patients living with ALS and their caregivers. Therefore, palliative care services must incorporate effective management of drooling into their care models. Both pharmacological and non-pharmacological interventions should be implemented for patients experiencing significant symptoms. Current practices in managing sialorrhoea can be enhanced by regular reassessment of patients over time, allowing for the timely initiation of evidence-based treatment options. Further follow-up of patients regarding the effectiveness of treatment is essential to ensure effective solutions. This approach will help in alleviating the multifaceted challenges faced by families, ensuring a better quality of life for those affected by this debilitating disease.