Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a progressive neurodegenerative disorder that affects motor neurons, or nerve cells controlling muscle movement.
The symptoms of ALS can occur at any age but usually begin around ages 55 to 75 and progress gradually. Muscles involved in speech and swallowing are generally affected first, followed by muscles in hands and legs, although the sequence of the emergence of symptoms can vary from person to person.
Depending on the stage of disease progression, ALS symptoms may range from mild to severe.
The muscular system is affected in the early and mid stages of the disease.
Muscle weakness is a common sign, and it gradually worsens in the disease’s mid-stages. This symptom affects the patient’s ability to walk, speak, and chew food. Patients also may experience poor balance or tripping while walking as a result of muscle weakness. Difficulty grasping objects with a tight grip is another common manifestation of this symptom.
Some patients may experience tremor-like symptoms, which are the result of muscle failure when muscles are pushed to their limit.
Some of these muscular symptoms might occur before diagnosis or could be due to other neurological complications.
In the mid-stages of the disease, paralysis also may be observed. Infrequently used muscles tend to get shortened (contractures), and joints may not fully straighten. Difficulties swallowing, breathing, and speaking all may be observed due to the weakening of the mouth, throat, and chest muscles.
In some cases, breathing difficulties are among the first symptoms of ALS, as the chest muscles and diaphragm that control breathing become affected. In other patients, breathing difficulties may only appear as the disease progresses, when almost all muscles of the body become paralyzed.
In either event, breathing will become increasingly difficult, and patients usually will require a ventilator by the later stages.
In addition to increased breathlessness, other breathing problems are reported among ALS patients. These include shallow breathing at night, which may cause sleep interruptions. Patients may also feel breathing discomfort while eating, speaking, sitting, or doing other activities.
Despite having a weak cough, patients often have difficulty clearing mucus from the lungs and throat, which in turn causes buildup and recurrent infections. Respiratory failure also may occur and can be life-threatening.
In some ALS patients, digestive symptoms are seen and may contribute to disease progression. These include constipation, cramping, bladder urgency, and a condition called delayed gastric emptying, in which the stomach doesn’t empty food as fast as it should.
Since these symptoms are mild, they often are not immediately noticed or attributed to ALS.
ALS also may change the composition of the harmless microorganisms that inhabit the digestive system and assist with food digestion — the so-called gut microbiome. Changes in the gut microbiome have been linked to a number of health conditions.
Around 85% of people with ALS experience dysphagia, or difficulties in swallowing. These problems usually occur in the later stages of the disease.
Swallowing requires the combined action of many different muscles of the lips, tongue, and throat. Any of these muscles can be affected in ALS, which impairs the swallowing process.
Difficulties in swallowing may not always be apparent, but there are several signs that can indicate that a problem exists. These include frequent coughing or choking on food while swallowing, and the spillage of food or liquid through the mouth or the nose. In these cases, a feeding tube usually becomes necessary.
Other signs of trouble may include a gurgling-sounding voice after swallowing and the pooling of saliva in the mouth; this may look like drooling.
The patient’s health and nutrient status also can be impacted by swallowing difficulties, due to reduced calorie intake. As such, these patients often experience unintentional weight loss.
Additionally, difficulty swallowing increases the risk of food or liquid going into the windpipe, which is called aspiration. Aspiration can cause infections and other complications.
Speech problems, or dysarthria, are common and among the first symptoms of ALS, occurring in about 80% of cases. They occur during the early stages and usually worsen as the disease progresses.
The speaking process involves many different nerves that control the movement of the lips, jaw, tongue, and vocal cords. ALS causes a reduction in the stimulation of these muscles by motor neurons such that their proper use becomes difficult. Some muscles that are involved in the speaking process also become weak over time because they are not used.
As a result, patients may have difficulties in managing the tone, pitch, and rhythm of the voice, and therefore their speech may become slow, slurred, and hard to understand.
Patients also may find it challenging to pronounce certain consonants and may have a nasal-sounding voice and hoarseness.
Anxiety and Depression
As with any serious illness, ALS has a huge impact on the day-to-day lives of patients, as well as those of their family members and caregivers.
As the condition progresses, patients usually retain their mental reasoning, thinking, and sensory abilities, and are aware of their progressive loss of motor function. This makes them prone to anxiety and depression, leading to changes in appetite and sleep, or even suicidal tendencies.
These symptoms are common in patients with ALS, particularly immediately following a diagnosis.
About 50% of patients with ALS experience some cognitive issues and behavioral changes. The symptoms may include childish behavior, loss of manners, lack of attention, and aggressiveness. Some patients even may develop a form of dementia.
PBA is thought to result from disruptions in the brain’s neural circuits that control the expression of emotions. However, the exact cause of PBA is still not clear.
These episodes often seem inappropriate, can be quite severe, and can occur several times a day. Embarrassment or anxiety caused by PBA may lead to isolation, which may affect patients’ employment or relationships.
Other symptoms can include abnormal fatigue of the arms and/or legs, which can either be experienced initially or in later stages.
At late-stage disease, severe symptoms such as pulmonary embolism, or a blood clot in a lung artery, and heart arrhythmias — irregular heartbeat — also may be observed. Patients at this stage also are more prone to have pneumonia.
Last updated: August 10, 2021
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