Myasthenia gravis (MG) is an autoimmune disease that produces fatigue and voluntary muscle weakness, both of which become worse with exercise and improve with rest. The muscles that are frequently involved include those for eye and eyelid movement, chewing and swallowing, breathing, and movement of the distal muscles of the extremities. This weakness progressively worsens during the day or at times of stress, so the greatest fatigue is likely to occur at the end of the day. MG frequently accompanies disorders of the immune system or the thyroid gland.
Rapid acute exacerbations result in a 5% mortality rate and are classified as either myasthenic or cholinergic crises. Both crises lead to extreme respiratory distress, difficulty in swallowing and speaking, great anxiety, and generalized weakness, thus making differentiation challenging but crucial for selection of appropriate intensive therapy. Myasthenic crisis is caused by undermedication, whereas a cholinergic crisis results from excessive anticholinesterase medication and is thus likely to occur within 45 to 60 minutes of the last drug dosage. The major complications of MG are respiratory distress or insufficiency, aspiration pneumonia, and the poor nutrition that is linked to eating difficulties.
Myasthenia gravis, thought to be an autoimmune disorder, is caused by a loss of acetylcholine (ACh) receptors in the postsynaptic neurons at the neuromuscular junction. About 80% of all MG patients have elevated titers for ACh receptor antibodies, which can prevent the ACh molecule from binding to these receptor sites or can cause damage to them. MG is often associated with thymic tumors.
Nursing care plan assessment and physical examination
Elicit a careful history of the patient’s symptoms and pay particular attention to changes that involve the eyes, which are often the earliest signs of MG. These changes include ptosis (eyelid drooping), diplopia (double vision), reduced eye closure, and blurred vision. Ask if the patient has to tilt the head back to see properly. Question the patient about weight loss because of problems with chewing and swallowing. Determine the patient’s ability to perform sustained or repetitive movements of the extremities, such as brushing the hair or carrying groceries. Determine if the symptoms are milder in the morning, worsen as the day progresses, and subside after short rest periods. Ask the patient if the head bobs when she or he is tired or if the jaw hangs open.
You may note a “masklike” or “snarling” appearance because of the involvement of the facial muscles. Note if the patient has weak neck muscles that cause difficulty in maintaining head position. Assess the patient’s posture and body alignment because the patient may slouch or walk with a slow gait. The patient’s voice may fade during conversation. Determine the symmetry of muscle strength and movement. Perform an eye examination to determine visual acuity and eye movement, which are often abnormal. When you auscultate the patient’s lungs, you may hear decreased breath sounds resulting from hypoventilation. The patient who has confirmed MG may develop acute exacerbations, which can occur in two forms: myasthenic or cholinergic crisis. Myasthenic crisis is caused by undermedication and is also characterized by hypoxia (associated with tachycardia and possible elevated blood pressure), absence of the cough and gag reflexes, ptosis, diplopia and mydriasis (large pupils), and a positive response to the medication edrophonium (Tensilon). In comparison, a cholinergic crisis results from excessive anticholinesterase medication and is likely to occur within 45 to 60 minutes after the last drug dose. Side effects of overmedication include diarrhea and abdominal cramping, bradycardia and possible hypotension, a flushed diaphoretic appearance, miosis (small pupils), and increased secretions (saliva, tears, and bronchial secretions). Response to Tensilon is negative, and twitching and “thick tongue” dysphagia may occur.
The course of MG is unpredictable because of its exacerbations and remissions. Patients live in fear of not being able to breathe adequately. Depression may occur in patients who experience exacerbations and functional limitations in their lifestyles and role responsibilities. Assess the family’s support system and ability to deal with chronic disease and any emergency situation that may occur.
Nursing care plan primary nursing diagnosis: Ineffective airway clearance related to difficulty in swallowing and aspiration.
Nursing care plan intervention and treatment plan
There is no cure for MG; treatment is predominantly pharmacologic. Plasmapheresis is reserved for patients who are refractory to conventional therapy, during myasthenic or cholinergic crisis, for prethymectomy stabilization and possible reduction in post-thymectomy ventilator therapy, or if unacceptable drug side effects develop. Plasmapheresis separates and removes circulating ACh receptor antibodies from the patient’s blood. A thymectomy is indicated for patients with a thymoma and for other selected patients with generalized MG. Thymectomy increases the chance of remission, increases long-term survival, decreases the chance of relapse after stopping immunosuppressant therapy, and allows better control of the disease. Thymectomy is most effective if it is performed early in the disease course. Improvement is recognized in 60% to 70% of thymectomy patients and coincides with complete remission in 20% to 40% of cases (although this remission may require several years to occur).
The primary nursing concerns focus on the adequacy of the patient’s airway and breathing. Keep suction equipment and intubation supplies at the patient’s bedside. For meals, place the patient in a completely upright position. Instruct the patient to swallow only when the chin is tipped downward and never to speak with food in his or her mouth. To prevent pulmonary complications, encourage the patient to perform deep breathing and coughing to enhance ventilation. If the patient requires surgery, instruct him or her on chest splinting during deep-breathing and coughing exercises. Keep the patient’s pain under control before all breathing exercises.
Ensure adequate nutritional intake and observe for sings and symptoms of dehydration or malnutrition. Work with the patient and family to plan for foods that are easy to chew and swallow but are still appealing to the patient. Plan mealtime to make the most of the patient’s energy peaks. Assist the patient in developing a method for reliable communication. Fear of sudden respiratory distress and the inability to call for help or to reach a call light is very real. If the patient requires hospitalization, locate the patient near the nurses’ station, keep a call light nearby at all times, and provide a secondary “call” system (such as a different-toned bell) for use during times of distress. Emphasize clear, honest communication about the realistic expectations of therapy because the time between initiation of the intervention and when the patient experiences improvement can be quite prolonged. Because treatment and improvement revolve around receiving the optimal dosages of medication, teach patients to recognize their disease status and the indications for self-determined dosage alterations to achieve an optimally effective drug benefit. Also teach the patients how to recognize the early signs of an overdose in order to prevent cholinergic crisis and when to selfmedicate with atropine for relief of side effects. Involve the patient in decision making and recognize the patient’s ability to manage her or his disease. Because these patients are frequently responsible for determining drug alterations at home, denying their judgment in determining drug dosages can cause them to feel very vulnerable and insecure. Delays in receiving their medications can cause distrust and may result in significant physical difficulty in swallowing the delayed medication. Incorporate the patient’s input on plans for scheduling physical activities around rest periods.
Assist the patient in working through any feelings of depression that can occur because of MG’s profound effect on lifestyle, roles, and responsibilities. Depression can also result from the disbelief by others of the MG diagnosis because the patient may appear to have suspiciously fluctuating symptoms. Provide encouragement to these patients to live full, productive lives. Educate the family and significant others on the fluctuation of MG, and place them in contact with support groups and the Myasthenia Gravis Foundation.
Nursing care plan discharge and home health care guidelines
Instruct the patient and family on the importance of rest and avoiding fatigue. Be alert to factors that can cause exacerbations, such as infection (an annual flu shot is suggested), surgery, pregnancy, exposure to extreme temperatures, and tonic and alcoholic drinks. Instruct the patient and family about drug actions and side effects, the indications for dosage alteration, and the selective use of atropine for any overdose. Stress the importance of taking the medication in a timely manner. It is advisable to time the dose 1 hour before meals for best chewing and swallowing. Explain the potential drug interactions (especially aminoglycosides and neuromuscular blocking agents, which include many pesticides). Encourage the patient to inform the dentist, ophthalmologist, and pharmacist of the myasthenic condition.
Instruct patients about the symptoms that require emergency treatment, and encourage them to locate a neurologist familiar with MG management for any follow-up needs. Suggest that they collect a packet of literature to take to the emergency department in case the available physician is unfamiliar with this disease. (The Physician’s Handbook is available on request from the MG Foundation.)
Instruct patients to wear MG identification jewelry. Suggest having an “emergency code” to alert family if they are too weak to speak (such as ringing the phone twice and hanging up). Instruct the family about cardiopulmonary resuscitation techniques, how to perform the Heimlich maneuver, how to contact the rescue squad, and how to explain the route to the hospital. Make a referral to a vocational rehabilitation center if guidance for modifying the home or work environment, such as a raised seat and handrail for the toilet, would be beneficial.