Swallowing characteristics in Amyotrophic Lateral Sclerosis

1 Introduction

Motor Neuron Disease (MND) is a term used for a set of disease caused as a result of degeneration of motor neurons, which are responsible for the somatic motor functions of the body. The commonest form of motor neuron disease is Amyotrophic Lateral Sclerosis (ALS), which affect the upper and lower motor neurons of limbs, head and neck. ALS is a rapidly progressive degenerative disease that involves the motor neurons of brain and the spinal cord. Signs of the disease depend on the areas affected: bulbar signs (which involves the motor neuron of the speech and swallowing functions) and spinal signs (which involves the motor neuron of upper and lower extremities).

One of the most detrimental effects of ALS is seen on the swallowing function. Swallowing is a complex function, which requires co - ordination between various phases. It consists of four phases: oral preparatory, oral, pharyngeal and oesophageal phases. A dysfunction in any of the phases of swallowing would lead to dysphagia or disordered swallowing. Dysphagia is a common sign observed and reported in patients with ALS. In a study done by Jani and Gore (2014), dysphagia was observed in all the patients with motor neuron disease. One or more phases of swallowing are affected in motor neuron disease as a result of various physiological changes. Dworkin and Hartman (1979) reported reduction in lingual motility and difficulty in chewing in patients with dysphagia.

Individuals with ALS usually require dietary modifications and enteral feeding tube (nasogastric tube or percutaneous endoscopic gastrostomy) to maintain nutrition. This may lead to compromise in the quality of life. Most of the studies focus on instrumental assessment of swallowing. However, clinical swallow examination gives important information on a patients swallowing status. Hence, a need was felt to study clinical signs of dysphagia in these individuals. Also, this information will be useful to the clinicians in determining the nature of dysphagia in the preliminary stages and assist them to make necessary referrals for swallowing assessments using instrumental measures.

2 Objectives

To study characteristics of dysphagia phasewise.

3 Methodology

The current study is observational in nature. Five patients with amyotrophic lateral sclerosis participated in the current study. The neurologist on the basis of electromyography, nerve conduction velocity studies and clinical examination made the diagnosis. Among the five patients 3 were males and 2 were females. The average age ranged between 50–60 years.

A detailed case history was taken for all the cases. Clinical Swallowing examination was done using the following protocol:

Detailed oral peripheral mechanism examination.

A checklist, which highlights phase wise dysfunction in swallowing, was considered for the swallowing assessment. The checklist was prepared by the researcher with reference to signs and symptoms of dysphagia as described by Logemann (1983).

Data was analyzed using percentage analysis for each symptom in oral preparatory, oral and pharyngeal phase.

The following Table 1 summarizes the phase wise symptoms of swallowing deficits seen in patients with ALS

4 Results

The current study aimed at profiling swallowing characteristics of patients with amyotrophic lateral sclerosis. It was observed that all the five patients who participated in the study presented with dysphagia and compromised nutrition. Among the five patients, four were fed though PEG while restricted dietary modifications like pureed food was given to one patient.

On dry swallow, it was noted that the time taken to elicit swallow reflex was elevated in all the patients. Detailed clinical swallowing assessment revealed that all five patients with ALS presented with difficulties in the oral and pharyngeal phase of swallowing. All the patients showed difficulty in holding the bolus and dribbling/drooling. 80% (4/5) of the patients revealed difficulty in mastication and formation of bolus. Bolus residue in the oral cavity was seen in all the patients. When a liquid bolus was given, cough before swallow was seen.

During the pharyngeal phase, delay in swallow reflex was noted in all the patients for all the consistencies. 80% (4/5) of the patients reported that there was nasal penetration during swallowing especially for liquids. Cough before and during the swallow was noted in all the patients. Change in voice quality was observed in all the patients. All the patients exhibited poor cough efficiency. Multiple swallow for a single bolus was noted in 60% (3/5) patients and throat clearing after swallow was seen in all the patients.

5 Discussions

ALS is a rare degenerative disease, which presents with bulbar signs like dysarthria and dysphagia. Literature reveals high incidence of dysphagia in patients diagnosed with ALS. The present study aimed at profiling the clinical characteristics of swallowing functions at oropharyngeal stages in patients with ALS.

All the patients that participated in the current study exhibited swallowing problems. Ruoppolo et al. (2013) reported chewing difficulties in 55% of their patients with ALS. Another study done by D’Ottaviano (2013) reported difficulties in oral preparatory phase in 73% of the patients. In the current study, four out of five patient (80%) patients revealed difficulty in chewing, hence forming the bolus. This can be attributed to the spasticity and weakness in the muscles of mastication.

In the present study, all the patients with ALS showed deficits in oral stage of swallowing due to poor bolus control in the oral cavity and poor oral transit. Residue in the lateral and anterior sulcus was also noted in almost all the patients. Kawai et al. (2003) reported similar findings early stage of dysphagia was mainly caused by dysfunction in the oral phase. Lingual weakness and wasting in motor neuron disease leads to reduction in the range of motion (lateral and elevation) of the tongue resulting in lingual dysfunction which is necessary for bolus control and bolus clearance in the oral cavity. This also affects the bolus transport anterior to posterior in the oral cavity. Ruoppolo et al. (2013) reported that the major factor causing dysphagia in ALS patients was impaired tongue muscles. D’Ottaviano (2013) reported difficulties in oral transit in all the patients with ALS due to impaired tongue muscles.

Four out of five patients (80%) in the current study presented with nasal regurgitation. Weakness in the palatal muscle leads to incompetent elevation of the soft palate and incomplete velopharyngeal closure, which leads to nasal regurgitation of the bolus. In the current study, delay in swallow reflex was noted in all the patients. The time taken to elicit a swallow was 3.5 seconds on average (<1 second being normal). Cough before and during swallow was noted in all the patients in the present study. This was caused due to poor lingual hold leading to premature spillage of bolus and incomplete laryngeal elevation and closure during swallow. Ertekin et al. (2000) observed similar findings where they found delay in swallow reflex trigger in patients with ALS. They attributed this delay to poor tongue control and sub mental muscle strength which results into premature spillage of the bolus into the airway. Kawai et al. (2003) observed deficits in ability to hold bolus at the posterior part of the tongue. Leder, Novella and Patwa (2004) studied 17 patients with diagnosis of ALS where they observed presence of pre swallow bolus flow to valleculae, pyriform sinuses and laryngeal vestibule.

Throat clearing and Gurgly voice quality was seen in all the five patients. This is one of the initial signs of laryngeal penetration of the bolus that may occur due to incomplete laryngeal elevation and closure. D’Ottaviano (2013) observed tracheal aspiration due to impaired pharyngeal phase in all the cases of ALS.

Four out of five patients (80%) needed multiple swallows to complete single bolus. This is caused due to poor pharyngeal clearance as a result of poor pharyngeal peristalsis. Briani et al. (1998) studied 23 MND patients and found that pharyngo - oesophageal motility and upper oesophageal sphincteric relaxation was impaired in these patients. Poor cough efficiency was seen in all the patients with motor neuron disease in the current study. Hadjikoutis, Wiles and Eccles (1999) contribute these changes to decreased inspiratory capacity, poor expiratory muscle strength, poor vocal glottis closure and poor voluntary cough capacity as a result of the disease.

6 Conclusions

Dysphagia is multistage in individuals with ALS. A detailed clinical swallowing examination is vital while assessing these patients. These results not only aid the clinicians in providing useful information about swallowing functions but also help in understanding the mechanism behind the deficits. Instrumental assessment is gold standard for diagnosis of dysphagia; however, clinical swallowing examination can prove to be important tool in absence of the instrumental assessment procedures.

It has been observed from the current study and review of literature that dysphagia in motor neuron disease involves more than one phase of swallowing. It is important to note these changes carefully and plan intervention by dietary modifications, swallowing therapy or suggesting enteral feeding mode depending on the severity of dysphagia and patient condition. Speech language pathologists play a key role as swallowing pathologists in diagnosing these problems and helping the patient maintain nutrition and improving the quality of life.

Conflict of interest

The authors of the article declare no conflict of interest.