What is Polymyositis?

Polymyositis is an autoimmune disease that generally causes muscle weakness, progressing within weeks to months. It is rare, affecting 1 in 100000, and will present mostly in persons in their 20s.¹ It is usually classified as one of the inflammatory myopathies; others which include dermatomyositis, necrotising autoimmune myositis, overlapping myositis, and inclusion body myositis.

Although the effect of inflammatory myopathy is mostly muscular, it can also cause problems with the gastrointestinal system.² These complications will be reviewed in this article, and their effects on the overall body system.

The cause for polymyositis has not been clearly defined. However, most research says it is associated with a viral illness that triggers the autoimmune nature of the condition.²

Structure of the gastrointestinal system

The gastrointestinal system or tract includes all the organs and processes involved in the breakdown of food for digestion, absorption, and excretion. The organs involved include the mouth, esophagus, stomach, small and large intestines, rectum, liver, biliary tract, and pancreas.³ 

The food that enters the mouth moves through the GI tract by a process called peristalsis. The muscles of the GI tract will contract to push the food down into the system for the digestive process to continue. It also, prevents a backwards flow of the food and stomach acids.³ 

Polymyositis and the gastrointestinal system

When a person has polymyositis (PM), the muscles of these gastrointestinal organs are weakened, leading to dysfunction in propelling the food; and this affects the way in which the overall GI tract works. Persons diagnosed with polymyositis will also complain of reflex and will find some good relief with anti-reflux meds and clinical management of the myositis².

The GI Manifestations

1. Dysphagia

Dysphagia is when there are problems affecting swallowing. It is recognised in the diagnostic criteria for myositis by the American College of Rheumatology/European League Against Rheumatism. The upper part of the gut and the oropharynx (middle part of the throat) are usually affected due to the inflammation and weakness associated with PM.

It can be an early or only symptomatic presentation in PM. Patients with dysphagia have poor throat movement and they will often have residue in their mouths as a result of their difficulty swallowing. Since the pharynx is also a pathway for air travelling into the lungs, aspiration can occur.⁴

Aspiration is when residue (solid or liquid) in the mouth enters the lungs instead of air. During breathing, air travels through the mouth into the throat (pharynx) through the airways (trachea) and into the lungs.⁵ There is a covering over the trachea that prevents food or drinks from passing into the lungs. However, in dysphagia, food or drink can escape into the airways, causing one to aspirate.

Aspiration is commonly reported by patients with PM. A simple way to screen for this is to check for the following:⁶ 

• Any problem keeping liquids in your mouth
• Do you start to cough after drinking?
• Do you get shortness of breath while drinking?
• Does your voice change after you have been drinking?
• Do you cough after you have eaten?
• Do you get any shortness of breath after eating?
• Do you get a feeling or sensation of food stuck in your mouth or throat after eating?
• Increased saliva production

Other symptoms as a result of dysphagia include 

• nasal speech
• a hoarse voice
• difficulty swallowing food while lying
• heartburn

2. Gastric emptying

Polymyositis can also cause delayed emptying by the gastric muscles after a meal.⁷ The factors influencing the rate of emptying also include the composition of the meal, whether solid, liquid, or semi-liquid. Other conditions such as diabetes mellitus and GORD can also cause delayed gastric emptying.⁸ However, polymyositis, it causes an abnormality of the smooth muscles of the gastrointestinal system.²

Normal gastric emptying involves the stomach storing the ingested food, and it being mixed with secretions from the gastric system and grounded into smaller particles before transportation to the small intestine for further digestion and absorption.

 Features of delayed gastric emptying

1. Gastrointestinal symptoms: The symptoms associated with delayed gastric emptying include nausea, feeling of fullness early causing poor diet and nutritional deficiencies. Some people will start to vomit in large quantities, some hours after eating
2. Slow absorption of drugs: It can also affect the rate at which drugs are absorbed into the system. Thus, persons with polymyositis will need to take this into consideration when taking medication where the desired effect is a rapid onset

Other conditions that can result from polymyositis include:

3. Gastroparesis
4. Reflux disease
5. Gut infections
6. Gastritis
7. Peptic ulcers

Diagnosis

If you are presenting with these gastrointestinal symptoms, the doctor will listen to your history, and carry out a physical exam, and some tests. They will also want to know if there is a family history of the condition and if your previous medical history will lead to other differentials.

A physical exam will also be done. Since polymyositis affects the muscles, they will assess if your muscles are well preserved and that there is no loss. A strength assessment of your muscles will also be carried out.⁹ The doctor may ask you to perform certain movements with your arms, legs, neck. They may resist those movements to check if they are weak or strong enough to complete the instructed movements.

Diagnostic tests

The diagnostic tests carried out include:

1. Blood tests: With blood tests the doctor will be checking for certain enzymes. There is an elevation of creatine kinase (Ck) and lactate dehydrogenase (LDH), consistent with damage to the muscles in polymyositis.¹⁰ In acute cases, test results might also indicate liver injuries with elevated ASK and ALT levels. Inflammatory indicators like the ESR and C-reactive protein may also be raised
2. Electromyography: This is done with a needle inserted into the muscles that are being tested for polymyositis.¹¹ The machine gives some readings that are indicative of the muscle activity, during contraction and relaxation
3. Nerve conduction testing: A nerve conduction test can also be done at the time of an electromyography, to test how fast nerve impulses are transmitted¹ 
4. Muscle biopsy: This is the process by which a small sample of the muscle is removed and tested under laboratory conditions. It is commonly done by the use of a special needle inserted into the muscle.¹² It is common for the affected area to be bruised, but follow the care instructions of your doctor

The selected muscle tissue considered will usually be the weakest from the physical testing, or from an MRI. An MRI can show the normal morphology of a muscle and those with damage.

For persons presenting specifically with dysphagia, as discussed earlier, there are other specific tests that can be ordered. They include:

1. Barium swallow test: This test will involve the swallowing of barium. The barium could be in different forms - solid, liquid, semi-liquid. After swallowing, the oesophagus is x-rayed immediately, showing the activity of the organ and revealing any abnormalities with swallowing¹⁵
2. An endoscopy can also be carried out of the upper gastrointestinal tract to visualize any abnormalities

Treatment

When treating polymyositis, the main goals are to reduce inflammation and improve muscle performance.¹³ The main choice of treatment are corticosteroids.² This helps to manage the inflammation and overactive nature of the immune system in polymyositis. Steroids are known to have other side-effects and it’s important to discuss this with your healthcare provider to prevent other organ damage.

Other drugs that will be considered by your doctor are drugs that work to suppress the immune system function like: methotrexate, azathioprine, cyclophosphamide, and cyclosporin A.² These drugs reduce an overdependence on steroids, but also come with their own side-effects.

In managing specific gastrointestinal manifestations with polymyositis, treatment and advice will include the following:¹⁴

1. Modification of diet to more softer solids or liquids for easier digestion
2. You might need to change your eating style or position. Generally, you will want to eat slower and chew well before swallowing. You will also want to eat at least two to three hours before going to bed. Older persons might elevate their bed to an angle
3. The doctor may prescribe proton pump inhibitors to suppress or inhibit gastric acid secretions
4. Understanding and avoiding any known triggers like spicy, acidic, and fatty foods
5. Some persons with PM will also be told by their doctors to avoid non-steroidal anti-inflammatory drugs like ibuprofen
6. Depending on the severity of your symptoms, you might be referred to a speech pathologist
7. You can liaise with your doctor on medications that can improve your gut motility. Some patients are injected with botulinum-toxin for more symptomatic relief⁴

Summary

Polymyositis will commonly present with gastrointestinal manifestations. This means that it will primarily affect the muscles you use to digest food. The symptoms include problems with swallowing (dysphagia), delayed gastric emptying, reflux disease, gastric infections, and peptic ulcers. Following diagnosis by the doctor, treatment will mainly consist of corticosteroids and dietary modifications.