an autoimmune neurologic disorder myasthenia gravis by lexi gray & mary kacic
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An autoimmune neurologic disorder Myasthenia GravisBy Lexi Gray & Mary Kacic
BackgroundMyasthenia gravis means grave muscle weaknessIt is an autoimmune disease affecting the myoneural junctionAbout 60,000 people in the U.S. have this diseaseWomen affected more frequently than men, at around 20-40 years of age. Men develop it later, at around 60-70 years of age.
SymptomsCauses varying degrees of skeletal muscle weaknessHallmark of the disease: muscle weakness increases during periods of activity and improves during rest. Areas that MAY be affected: eyes/eyelid movement, facial expression, chewing, talking, swallowing
PathophysiologyNormal communication between the nerve and muscle is interrupted at the neuromuscular junction (where nerve cells meet with the muscles they control) Normally, nerve endings release acetylcholine which travels through the NMJ and binds to receptors, causing muscle contraction. In myasthenia gravis, these receptors are blocked or destroyed
Autoimmune disease: the antibodies that attack or block the acetylcholine receptors are produced by the bodys own immune systemThymic hyperplasia or a thymic tumor is present in 80% of people with myasthenia gravisPathophysiology
AssessmentOnset of the disorder may be suddenMany times, symptoms are not immediately recognized as being related to myasthenia gravisIn most cases, weakness of the eye muscles is noticed first.
Assessment - Severe SymptomsPtosis drooping of one or both eyelidsDiplopia blurred or double visionBulbar symptoms weakness of muscles of the face & throatBland facial expressionDifficulty swallowing increased risk of choking & aspirationDysarthia impaired speechDysphonia voice impairmentWeakness In arms, hands, legs, neckGeneralized weakness also effects intercostal muscles, resulting in decreasing vital capacity and respiratory failure.
Confirming the DiagnosisAcetylcholinesterase Inhibitor TestConfirms the diagnosis of myasthenia gravis. During this test, the breakdown of acetylcholine is stopped. As a result, acetylcholine is able to accumulate at the receptor sites. For this test, edrophoniumchloride is administered IV. Facial muscle weakness and ptosis will resolve about 30 second after the drug is administered, if the patient is positive for a myasthenia gravis diagnosis. This relief lasts only 5 minutes, so it is not considered a treatment. After the drug is administered, the patient's serum is then tested for acetylcholine receptor antibodies, which would also be consistent with the diagnosis. In some cases, patients with myasthenia gravis may have an enlarged thymus gland.
Nursing Diagnosis #1Risk for aspiration R/T difficulty swallowing, weakness of bulbar musclesOverall goal: No aspiration will occurInterventionsGive meals with anticholinesterase meds to inhibit breakdown of acetylcholine and increase its concentration at the NMJRaise the HOB to semi-fowlers position, which will ensure upper airway patency. Give food with a pudding-like consistency, which can be more easily swallowed.
Nursing Diagnosis #2Deficient knowledge R/T drug therapy, potential for crisis (myasthenic or cholinergic), and self-care managementOverall goal: Patient will demonstrate knowledge of medication management, importance of rest, coping strategies, and prevention/management of complicationsInterventionsTeach patient about the actions of meds, and importance of regimen. The patient will verbalize the consequences delaying med intake, including S&S of myasthenic and cholinergic crisis.Teach strategies for patient to conserve their energy. The patient will develop coping strategies to avoid overexertion. If eyes cannot close properly, instruct patient to patch/tape eyes closed for short intervals to avoid corneal damage.
Treatment of myasthenia gravisPharmacologic TreatmentFirst-line med is pyridostrigmine bromide (Mestinon), an anticholinesterase that inhibits the breakdown, thus improving skeletal muscle contraction. Side effects can include fasciculations, abdominal pain, diarrhea. Immunosuppressive Therapy: Corticosteroids decrease the amount of antibody production. Cytotoxic meds (Azathioprine) inhibits production of T-and B-cells, and effects may not be seen for 3-12 months. Hepatotoxicity is a risk of using cytotoxic meds.Some common medications exacerbate the symptoms of myasthenia gravis, including: antibiotics, beta-blockers, antiseizure meds, Novocain, morphine and quinine.
Possible Side Effects of Anticholinesterase Meds
Central Nervous SystemRespiratory/CardiovascularSkeletal MusclesIrritabilityBronchial relaxationFasciculationsAnxietyIncreased bronchial secretionsSpasmsInsomniaTachycardiaWeaknessHeadacheHypotension GenitourinaryDysarthiaGastrointestinal FrequencySyncopeAbdominal crampsUrgencySeizuresNausea, vomiting and diarrheaIntegumentaryComaAnorexiaRashDiaphoresisIncreased SalivationFlushing
TreatmentsPlasmatheresisThis procedure removes the patients plasma and plasma components through a centrally placed catheter. Blood cells are separated from antibody-containing plasma. The blood cells are then mixed with plasma substitute and reinfused. Provides temporary treatment for severe symptoms. Intravenous immune globulinTreats exacerbations of myasthenia gravis temporarily. This procedure does not work as quickly as plasmatheresis. These are treatments for myasthenia gravis, not cures.
TreatmentsSurgical TreatmentsThymectomy: Surgical removal of the thymus gland, which may result in the production of antigen-specific immunosuppression, which results in clinical improvement. Results vary; patient may have partial or complete remission, or no remission at all. Nursing considerations for the patient who received a thymectomy include monitoring respiratory function and mechanical ventilation.
Myasthenia (or cholinergic) CrisisExacerbation of the disease process. Signs & symptoms include muscle/bulbar weakness. Causes for myasthenia crisis may include a respiratory infection, pregnancy, or medications. Primary management is focused on maintaining the airway. The nurse assesses respiratory rate, depth, breath sounds, and pulmonary function. Endotracheal intubation and mechanical ventilation may be necessary. Assess arterial blood gases, I&O, daily weight.Avoid sedatives and tranquilizers. Bradycardia and respiratory distress (emergency situations) are treated with atropine.
References Doenges, M., Moorhouse, M., Murr, A. (2010). Nurses Pocket Guide: Diagnoses, Prioritized Interventions, and Rationales (12th ed.). Philadelphia: F.A. Davis. ISBN: 0803622341.Smeltzer, S. C., Bare, B. G., Hinkle, J. L. & Cheever, K. H. (eds.) (2008). Brunner & Suddarth's textbook of medical-surgical nursing (11th ed.). Philadelphia: Lippincott Williams & Wilkins.