1.Learning objectives are
1) To understand the differences in the incidence pattern of dysphagia associated with neuromuscular disease
2) To understand the characteristics and management of dysphagia in the following major neuromuscular diseases:
･Amyotrophic lateral sclerosis
･Parkinson's disease
･Muscular dystrophy
･Myasthenia gravis
2.Classification of neuromuscular diseases based on the development patternof dysphagia
1) Rapid progressive dysphagia:
Amyotrophic lateral sclerosis (ALS), etc
2) Slow progressive dysphagia:
Parkinson's disease (PD)-related diseases (eg, PD, progressive supranuclear palsy [PSP])
Multiple system atrophy (MSA), spinocerebellar degeneration (SCD)
Muscular dystrophy
Duchenne muscular dystrophy, myotonic dystrophy
(note that management vary depending on disease type)
3) Fluctuating dysphagia
PD with fluctuating symptoms, myasthenia gravis (MG), multiple sclerosis (MS), etc
In this module, representative diseases are explained.
3.Dysphagia in Amyotrophic Lateral Sclerosis (ALS)
1) Anticipatory stage disorders
Muscle weakness of the upper limbs and neck, drooping head, impaired coordination of breathing and swallowing
Difficulty or inability to protect the airway, depressive symptoms, cognitive impairment
2) Oral stage disorders
Weakness of the masticatory muscles, weakness of mouth closure, perioral muscle weakness, difficulty in retaining saliva, salivation, tongue atrophy and musclular fasciculation, reduced masticatory force, velopharyngeal insufficiency
3) Pharyngeal stage disorders
Weakness of the palatal and/or pharyngeal muscles, incomplete cricopharyngeal muscle relaxation, vocal cord dysfunction, delayed swallowing reflex, aspiration, impaired elevation of the hyoid, residue (pooling) in the vallecula and/or piriform sinus
4) Esophageal stage disorders
Usually this stage is not affected by any disorders
5) Other disorders
Reduced force of expectoration, rapid changes in time course, malnutrition
4.Changes over time of dysphagia in ALS
1) Either pharyngeal stage disorders or oral stage disorders may precedingly be dominant. Advanced disease may significantly affect both stages.
2) Some patients empirically or unconsciously acquire compensatory techniques, such as head/neck flexion when swallowing. Assessing the appropriateness of such techniques is important and also leads to a better relationship with patients.
3) Respiratory failure and dysphagia can progress in parallel. The onset of respiratory failure indicates the presence of dysphagia.
Figure: Respiratory failure (%FVC) and dysphagia (FRSsw) progress in parallel.
5.Nutrional management for ALS
･Malnutrition affects the survival outcome of patients, so it is important to initiate nutritional management from an early stage of disease.
･Malnutrition may coexist with early stage dysphagia and patients may not know this.
･Periodic nutritional assessment is needed to minimize weight loss.
･In the advanced stage of ALS, when respiratory management is required and energy consumption is increasingly reduced, energy intake should be adjusted accordingly to avoid excessive calorie intake.
･Insufficient oral intake will lead to early introduction of tube feeding.
･Gastrostomy may worsen respiratory failure, so it should be performed in patients with %FVC ≥ 50%. The benefits and risks of gastrostomy should be fully explained to the patient and family and if consent is obtained, the procedure should be done before respiration failure progresses.
6.Management of dysphagia in ALS
･Early diagnosis of dysphagia and intervention: Patients may not be aware of or may not want to admit that they have dysphagia. Assess whether their dietary habits are suited to their eating and swallowing function.
･Rehabilitation should keep remaining function: This is effective for disuse syndrome.
･Periodic assessment: Starting periodic assessment of swallowing and nutritional and respiratory status immediately after ALS diagnosis leads to early diagnosis of dysphagia.
･Prevention of aspiration for patients with recurrent aspiration: suggesting the surgical prevention of aspiration.
･Help with acceptance: Help patients to understand and accept their illness because dysphagia can progress too fast for patients to accept it.
･Respect the joy of taste: Propose alternative approaches such as only tasting food (without swallowing it). Providing mental care is important.
･Predicting upcoming disorders: Help patients to understand and accept their illness by advance planning of nutritional supplementation, PEG, concurrent respiratory management, surgical prevention of aspiration, and other measures.
･Management of respiratory failure and dysphagia: Pay attention to providing coordinated management of respiratory failure and dysphagia, because respiratory failure may affect swallowing function. Patients' wishes to not receive respiratory management should be respected, if applicable.
7.Characteristics of dysphagia in patients with Parkinson's disease
･Affects more than 50% of PD patients
･May coexist with early stage PD (including Hoehn-Yahr stage I cases)
･Not correlated with PD severity
･Patients tend to be unaware of dysphagia and often experience silent aspiration
･Various disorders affect various stages of swallowing
･Influenced by the pharmacological and adverse effects of antiparkinson drugs
･Patients can sometimes pass out due to postprandial hypotension (blood pressure decrease of ≥20 mmHg while eating or within 2 hours after meal due to autonomic nervous system disorder) and can suffocate from food particles blocking the airway
･Surgical treatment for PD (ex: deep brain stimulation) may lead to improved motor symptoms, but with no change or even worsening of dysphagia
･Patients have reduced expiratory acceleration (coughing), and its severity correlates with the incidence of aspiration
8.Various disorders in PD (including those induced by anti-parkinson drugs)
1) Anticipatory stage: depressive symptoms, cognitive impairment, rigidity and/or tremor of the upper liUmbs and/or jaws, postural abnormality of the head and/or neck (Pisa syndrome)
2) Oral stage disorders: bradykinesia, tremor, or dyskinesia of the tongue and masticatory muscles, dry mouth, salivation, rigidity of the tongue and perioral muscles
3) Pharyngeal stage disorders: delayed swallowing reflex, reduced pharyngeal contraction, reduced laryngeal elevation, residue (pooling) in the vallecula and/or piriform sinus, aspiration
4) Esophageal stage disorders: upper esophageal sphincter dysfunction, reduced esophageal peristalsis, gastroesophageal reflux
Postprandial hypotension, worsening of dysphagia during off periods
9.Management of dysphagia in PD
･Manage PD-related motor dysfunction with medication and rehabilitation.
･Patients with suspected PD, even without any complaints, should be screened for PD for early diagnosis of dysphagia.
･Patients diagnosed with dysphagia should be prescribed a dysphagia diet suited to their swallowing function and advised on appropriate positioning.
･If patients show "wearing off", change the timing of antiparkinson drug administration from after meals to before meals and direct the patient to take the drug after entering the "on" phase.
･Make efforts to prolong the "on" time and have the patient eat during the "on" phase.
･Carefully monitor patients with postprandial hypotension during meals and advise them to try to rest for about 2 hours after eating by avoiding standing, walking, and even sitting if necessary.
･Patients with dysphagia due to neuroleptic malignant syndrome may experience aspiration pneumonia when they are directed without due care to eat orally during the acute phase. For these patients, it is recommended that tube feeding be introduced palliatively and after recovery, and that swallowing function be reassessed and oral feeding resumed.
･For disuse syndrome, interventions and a continuous rehabilitation plan are needed.
･Support for caregiver is needed for long-term adherence to a dysphagia diet, such as developing appropriate menus and providing cooking instructions.
･Complication measures are needed for complications of prolonged PD, such as pneumonia and malnutrition, and complications of enteral nutrition.
10.Patients with wearing-off should take L-dopa before each meal to have diets during their 'on' time
･Patients should have meals during "off-time" when medication is no longer working well (and thus dysphagia is severe).
･Patients can have meals during "on-time" when medication is working (and thus swallowing is at its best)
11.Dysphagia in Duchenne muscular dystrophy (DMD)
Anticipatory stage: weakness of the upper limb muscles, spinal deformity, respiratory failure
Oral stage: occlusal insufficiency, incomplete lip closure, macroglossia, impaired tongue movement, impaired masticatory movement
Pharyngeal stage: weakness of the pharyngeal muscles, residue (pooling) in the vallecula and/or piriform sinus, delayed swallowing reflex, aspiration, reduced laryngeal elevation
Esophageal stage: upper esophageal sphincter dysfunction, gastroesophageal reflux
12.Key points in the management of dysphagia in DMD
1) Oral stage disorders, such as occlusal interference and macroglossia, occur around the mid-teens and pharyngeal stage disorders due to weakness of the pharyngeal muscles occur around age 20. So, patients with early to mid-stage disease are able to swallow liquid almost normally and can be nutritionally managed by enteral nutrition.
2) Monitor patients carefully as patients tend to be unaware of dysphagia because DMD progresses slowly.
3) Patients may have an eating disorder due to spinal deformity and/or weakness of the upper limb muscles. Monitor patients with tachycardia or significant body movement for signs of fatigue.
4) Respiratory failure affects swallowing. Patients with early stage respiratory failure are usually on and off mechanical ventilation during the nighttime and daytime, respectively. If SpO2 is reduced during eating due to increased burden on breathing, put the patient on mechanical ventilation while eating.
13.Dysphagia in myotonic dystrophy (MD)
1) Patients tend to have aspiration without knowing it.
2) Aspiration and choking appear to affect the prognosis.
3) Liquid dysphagia is more serious. (Note that this is not the case in DMD.)
4) MD affects all stages of swallowing, including anticipatory stage disorders (eg, abnormal eating behavior), preparatory stage disorders (eg, malocclusion), oral stage disorders (eg, velopharyngeal insufficiency), pharyngeal stage disorders (eg, pharyngeal residue, aspiration), and esophageal stage disorders (eg, esophageal dilatation).
Anticipatory stage: cognitive impairment, abnormal eating behavior (patients tend to be unaware of the problem and continually overfill their mouth with food), high risk of choking during eating, influence of respiratory failure
Oral stage: occlusal insufficiency, incomplete lip closure, impaired tongue movement, velopharyngeal insufficiency, impaired masticatory movement
Pharyngeal stage: weakness of the pharyngeal muscles, reduced laryngeal elevation, residue (pooling) in the vallecula and/or piriform sinus, delayed swallowing reflex, aspiration (usually not accompanied by a clearing cough)
Esophageal stage: abnormal or delayed esophageal peristalsis
14.Key points in the management of dysphagia in MD
･Patients tend to have aspiration without awareness and can experience sudden aspiration and choking requiring emergency admission to hospital. Routinely provide patient education.
･Provide education for home care to patients with abnormal eating behavior, such as overfilling their mouth with food, because they are at increased risk of choking.
･It should be important to remember that liquid dysphagia is more serious, unlike the case for DMD.
･Periodically assess oral care, which may appear to be independently done, because it tends to become insufficient with progressing muscle weakness.
･Be careful not to overlook any effects of respiratory failure.
15.Characteristics of dysphagia in Myasthenia Gravis (MG)
･Caused by weakness of the swallowing muscles
Impaired soft palate elevation, impaired elevation of the hyoid
･Fatigue may be manifested due to eating in some cases. Masticatory movement improves during the latter half of the meal in some cases
･Symptoms show remission and exacerbation
･Dysphagia may become very serious after thymectomy or due to crisis
･May initially manifest as bulbar symptoms in some disease subtypes (eg, anti-Musk antibody-positive disease)
･The tensilon test is useful for the diagnosis of MG and the development of a treatment strategy
･Aspiration further worsens MG symptoms
16.Management of dysphagia in MG
･Manage varying symptoms in a timely manner and provide patient education
･Detect fatigue of the masticatory and swallowing muscles early
･Discontinue oral food intake during exacerbation or crisis
Instrcut patients not to force themselves to eat because the swallowing condition may ameliorate.
It should be remembered that aspiration can worsen overall MG symptoms.
･Monitor patients for signs that the dysphagia is worsening (e.g. difficulty speaking, nasal voice, discomfort in throat, nasal reflux of liquids)
