Myasthenia Gravis

Myasthenia gravis (MG) is a rare neuromuscular disease.^1,2 The most common cause of MG is the presence of autoantibodies against functional and structural neuromuscular junction proteins: the acetylcholine receptor (AChR), low-density lipoprotein receptor-related protein 4 (LRP4), and receptor-associated protein muscle-specific tyrosine kinase (MuSK-Ab).^1,3,4 Despite being an autoimmune disease, MG may also develop from abnormalities at the neuromuscular junction.^1,2 About 10% to 15% of patients with MG present with a tumor in the thymus gland, which can contribute to MG development.³

Patients with MG experience muscle weakness of the ocular, bulbar, respiratory, axial, and limb muscles.² This weakness may lead to partial paralysis of eye movements and double vision, as well as to weakness and fatigue of the neck and jaw with consequent difficulties in holding the head, chewing, swallowing, coughing, and breathing.^3,5 About 10% of patients with MG may experience a life-threatening myasthenic crisis characterized by impairment of the respiratory muscles.¹ Treatment of MG relies on the use of cholinesterase inhibitors to tackle symptoms, immunosuppressants, or surgery for thymus removal.¹

Managing Nutrition in Myasthenia Gravis

Fatigue and difficulties chewing and swallowing can compromise nutrition in patients with MG. Difficulty chewing results from jaw fatigue as the meal progresses.^2,5 Swallowing is affected due to weakness in the pharyngeal and/or tongue muscles. Dysphagia is more common with liquids than solids.²

A healthy diet that is adapted to the patient’s condition is important to help patients achieve a good nutritional status. The consistency of the food, softer for solids and thicker for liquids, can help reduce difficulties and safety concerns while chewing and swallowing. Meals can be planned for times when the patient shows optimal strength, such as after a period of rest or around the peak time of medication. Increasing the number of meals per day, reducing the portions ingested in each meal, and eating slowly are also important.⁶

Certain medications prescribed to control MG symptoms, such as cholinesterase inhibitors, may cause gastrointestinal issues. In this case, dairy products, raw vegetables, coffee, and spicy and greasy foods should be avoided.⁶

Managing Speech and Vision Difficulties in Myasthenia Gravis

Patients with MG may experience vocal fatigue and slurred speech as the disease impacts the vocal tract. Managing the time spent talking and performing muscle-strengthening exercises can help reduce fatigue. Taking rest breaks and using other forms of communication, such as written communication, are strategies that patients can consider while working.⁶

Ocular symptoms deriving from MG are commonly observed at the onset of the disease.⁴ As the muscles controlling the eyes fatigue, ptosis and diplopia occur.¹ Using large-print materials or magnifiers while working can help reduce difficulties in vision. Installing adequate lighting and periodically resting are also important. Patients with double vision may benefit from covering one eye with a patch.The patient can alternate the eye patch from one eye to the other to avoid eye strain.⁶

Exercise in Myasthenia Gravis

Exercise can improve muscle strength and daily function and positively influence muscle weakness in patients with MG.⁷ It is important that patients follow an exercise routine that includes rest periods, breathing exercises, and adequate sleep time.⁶ A minimum of 150 minutes of weekly exercise has been recommended for patients with MG presenting with mild to moderate disease.⁷

Living With Myasthenia Gravis

Although there is no cure for MG, there are many tips that can help patients navigate the disease in their daily lives and activities. Managing the time spent standing or doing other activities such as cleaning or exercising can be important to allow patients to conserve their energy.⁶ If traveling, patients with MG will benefit from planning the trip and discussing this plan with their MG care team. Planning for time to rest and avoiding heat, as this may exacerbate symptoms, should be part of this plan.⁵ Patients should be aware that there are many prescribed drugs that can cause worsening of symptoms in MG. These include aminoglycoside and quinolone antibiotics, beta blockers, local anesthetics, opioids, and anticonvulsants.⁸ Carrying a medical alert ID as a bracelet or a card may be helpful in the event of an emergency.^6,8 

Patients with MG can also follow a few suggestions to reduce the risk of injury when at home. These include scheduling annual eye exams, avoiding overheating the rooms, using a walker or cane when there is difficulty walking, and ensuring bright lightning in all rooms including at the top and bottom of the stairs.⁹

Living with a chronic disease can bring a toll of emotional burden and stress to patients and caregivers. There are many sources with informative and educational materials that can help patients understand the disease and better adapt to daily changes. The Myasthenia Gravis Foundation of America (MGFA) provides information and support to patients with MG and their families.¹⁰ The foundation website includes information and helpful tips on home injury prevention, how to adapt when performing daily activities, and wellness strategies for patients and caregivers.^5,6,9 Patients can download the myMG app, which allows them to register information to help track their MG and promote a more interactive dialogue with the MG care team.¹¹ The MGFA also promotes online support group meetings for patients and their caregivers.^12,13

Other organizations that provide information and support in MG include the Muscular Dystrophy Association,³ the National Organization for Rare Disorders (NORD),¹ and Myaware.¹⁴

References

1. Myasthenia gravis. National Organization for Rare Disorders (NORD). Accessed February 1, 2022.

2. Hehir MK, Silvestri NJ. Generalized myasthenia gravis: classification, clinical presentation, natural history, and epidemiology. Neurol Clin. 2018;36(2):253-260. doi:10.1016/j.ncl.2018.01.002

3. Myasthenia gravis (MG). Muscular Dystrophy Association. Accessed February 1, 2022.

4. Mantegazza R, Cavalcante P. Diagnosis and treatment of myasthenia gravis. Curr Opin Rheumatol. 2019;31(6):623-633. doi:10.1097/BOR.0000000000000647

5. Managing your MG. Myasthenia Gravis Foundation of America. Accessed February 1, 2022.

6. Wellness strategies. Myasthenia Gravis Foundation of America. Accessed February 1, 2022.

7. Gilhus NE. Physical training and exercise in myasthenia gravis. Neuromuscul Disord. 2021;31(3):169-173. doi:10.1016/j.nmd.2020.12.004

8. Myasthenia gravis (MG): medical management. Muscular Dystrophy Association. Accessed February 1, 2022.

9. Home injury prevention. Myasthenia Gravis Foundation of America. Accessed February 1, 2022.

10. About us. Myasthenia Gravis Foundation of America. Accessed February 1, 2022.

11. Welcome to myMG. Myasthenia Gravis Foundation of America. Accessed February 1, 2022.

12. MG community. Myasthenia Gravis Foundation of America. Accessed February 1, 2022.

13. Find MG support groups. Myasthenia Gravis Foundation of America. Accessed February 1, 2022.

14. Our mission. Myaware. Accessed February 1, 2022.

Reviewed by Harshi Dhingra, MD, on 2/4/2022.

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Diana Diez Gaspar, PharmD, PhD

Diana earned her PhD and PharmD with distinction in the field of Medicinal and Pharmaceutical Chemistry at the Universidade do Porto. She is an accomplished oncology scientist with 10+ years of experience in developing and managing R&D projects and research staff directed to the development of small proteins fit for medical use.