Muscle weakness can be frightening, and the cause isn’t always clear. Two conditions that can affect the face are myasthenia gravis (MG) and Bell’s palsy. Both disorders affect muscle control, which can make them hard to tell apart. MG is sometimes called “the great imitator” because it shares symptoms with other neurological conditions, including Bell’s palsy. While it’s rare for these two conditions to look exactly alike, they do have some similarities. A doctor can help figure out what’s causing your symptoms and find the right treatment for you.

What Is Myasthenia Gravis and Bell’s Palsy?

MG is an autoimmune disease, meaning the body’s immune system attacks itself. As a result, the body produces antibodies that attack the neuromuscular junction, the connection between nerves and muscles. Think of the nerves as messengers and the muscles as workers. In MG, this handoff is disrupted, preventing signals from reaching the muscles and causing weakness. Because MG results from the immune system attacking the body, it isn’t passed down in families or spread from person to person. However, in rare cases, some people may have a genetic risk for developing it.

Bell’s palsy is a condition in which the facial nerves become inflamed. The swelling compresses the nerve, reducing the signals sent to the muscles. This means the muscles on that side of the face will be weak. The exact cause of Bell’s palsy isn’t known, but some associated diseases might contribute to the condition:

• Viral infections, such as herpes simplex virus or Epstein-Barr virus
• Diseases such as Lyme disease, Guillain-Barré syndrome, or sarcoidosis
• Diabetes
• Increased blood pressure

Pregnancy and exposure to toxins or infections can also increase the risk of developing Bell’s palsy.

Similarities Between Myasthenia Gravis and Bell’s Palsy

While MG and Bell’s palsy differ in many aspects, there are slight similarities between the two. Both conditions affect the nerves and muscles, leading to problems with movement and control. Though their causes are different, they can sometimes appear similar, especially when facial muscles are involved.

Symptoms

The main similarity between MG and Bell’s palsy is that both can cause muscle weakness. When MG affects the facial muscles, it can look similar to Bell’s palsy. Here are the symptoms that can occur in both conditions:

• Weakness of the eye muscles
• Drooping of one or both eyelids (ptosis)
• Trouble controlling facial expressions (such as smiling or squinting)
• Problems with eating or swallowing
• Difficulty speaking (dysarthria)
• Visual changes, such as blurred vision
• Drooling

In addition to their similar appearance, the groups of people affected by these conditions also overlap. Both MG and Bell’s palsy can occur at any age. According to the National Institute of Neurological Disorders and Stroke (NINDS), they can affect anyone, regardless of gender or race.

Diagnosis

The diagnostic workup for these conditions can look slightly similar. First, the doctor will assess your medical history and do a neurological and physical exam. For Bell’s palsy, they may take a close look at your facial muscles. For MG, the provider may evaluate overall muscle strength and coordination, including eye movement. A provider may do a nerve test with an electromyogram (EMG) for either condition. EMG uses small needles to check how well the nerves and muscles are “talking to” each other and if there’s any nerve damage.

There isn’t a specific test that can diagnose Bell’s palsy, so blood tests or imaging studies can help eliminate other conditions, but they may not be needed. Blood tests for MG, however, can help confirm the diagnosis by seeing if certain antibody levels are elevated.

Differences Between Myasthenia Gravis and Bell’s Palsy

Despite their similarities, there are differences between the conditions as well. These differences help healthcare providers determine a diagnosis and treatment options.

Who Is Affected

Although both conditions can occur at any age and in any race, they tend to appear in different age groups. NINDS reports that MG typically shows up in women under the age of 40 and men over the age of 60. Bell’s palsy is more common between the ages of 15 and 60. While there is some overlap, Bell’s palsy tends to occur in a broader age range than MG.

Other Symptoms

While both conditions cause muscle weakness, they affect different parts of the body. MG can weaken muscles throughout the body, while Bell’s palsy is limited to the face. Unlike Bell’s palsy, MG symptoms may come and go, sometimes getting worse with activity and improving with rest.

In addition to affecting the muscles in the face, MG can affect all muscles, unlike Bell’s palsy. The muscles of the arms and legs are commonly affected, which leads to weakness. MG can also affect the muscles you use to breathe, causing shortness of breath. In severe cases, a myasthenic crisis can occur. This is a medical emergency because it makes it hard to breathe, sometimes to the point of needing a ventilator.

Bell’s palsy has a few other specific symptoms as well. Since it’s just one cranial nerve that’s affected, the symptoms usually just show up on one side of the face. Along with muscle weakness, you may experience a loss of taste on the front part of the tongue or increased sensitivity to sound on one side.

Treatments

The treatment choices for each condition are different. MG has a few treatment options:

• Anticholinesterase medications — These medications can help keep acetylcholine (a chemical that sends signals from nerves to muscles) in the neuromuscular junction for longer, which can improve communication between the nerves and muscles. This helps to improve muscle strength.
• Immunosuppressive drugs — These drugs aim to decrease the body’s overactive immune system.
• Plasmapheresis and intravenous immunoglobulin — These are short-term therapies that target the antibodies of the overactive immune system. They’re only used when symptoms are severe.
• Surgery — The thymus gland, which helps control the immune system, is believed to play a big role in MG symptoms. The thymus can be removed in a procedure called a thymectomy.

Your doctor will talk you through all of the treatment options and help determine which ones might be best for you.

Bell’s palsy is closely linked to inflammation, so the main treatment is a dose of steroid medications to help reduce the swelling. If your doctors are able to determine a specific cause for your Bell’s palsy, such as an infection, they’ll likely also give you a medication to target that disease (such as an antibiotic or antiviral medication — e.g., valacyclovir). Since a common symptom of Bell’s palsy is the inability to close one eye, eye care is an important part of treatment as well. This might include eye drops, ointments, or the use of an eye covering, such as an eye patch.

Prognosis

Most people with MG have a lifespan similar to those without the condition. While the overall life expectancy is generally normal with good management, some might continue to have significant symptoms. For the best prognosis, managing your symptoms is key.

Most people with Bell’s palsy will recover completely without treatment. Full recovery can take up to six months. Others may have permanent facial weakness. People who have more severe facial paralysis or other health conditions may experience worse outcomes than those who recover completely.

Although MG and Bell’s palsy share some similarities, they are different conditions with their own treatment approaches. Working with a healthcare provider can help you manage symptoms and find the best treatment for your needs.

Talk With Others Who Understand

MGteam is the social network for people with myasthenia gravis and their loved ones. On MGteam, more than 2,800 people come together to ask questions, give advice, and share their stories with others who understand life with MG.

Have you had symptoms of either Bell’s palsy or MG? What challenges did you face in getting a diagnosis or treatment? Share your experience in the comments below, or start a conversation by posting on your Activities page.