CONCEPTUAL PRESENTATION IN PATHOPHYSIOLOGYI. DEFINITION (Introduction)Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized byvarying degrees of weakness of the skeletal (voluntary) muscles of the body. The namemyasthenia gravis, which is Latin and Greek in origin, literally means "grave muscleweakness." With current therapies, however, most cases of myasthenia gravis are notas "grave" as the name implies. In fact, for the majority of individuals with myastheniagravis, life expectancy is not lessened by the disorder.The hallmark of myasthenia gravis is muscle weakness that increases during periods ofactivity and improves after periods of rest. Certain muscles such as those that controleye and eyelid movement, facial expression, chewing, talking, and swallowing are often,but not always, involved in the disorder. The muscles that control breathing and neckand limb movements may also be affected.II. PREVALENCE AND POPULATION AT RISKMyasthenia gravis affects approximately 2 out of every 100,000 people and can occur at anyage. It is most common in women between the ages of 18 and 25. In men, the condition usuallydevelops between 60 and 80 years of age.III. RISK FACTORS: ENVIRONMENTAL, PERSONAL AND DEVELOPMENTAL FACTORSMyasthenia Gravis is an autoimmune disease. For reasons that are notunderstood, the bodys immune system, which normally fights infectionsor cancers, attacks the nerve-muscle communication point. In about onein ten Myasthenia Gravis patients, the disease is caused by a tumor calleda thymoma that stimulates the immune system to attack the nerve-muscle junction. It is thought that what causes the disease in otherpatients is a combination of genetic factors and one or moreenvironmental problems. The best guesses of environmental causes areviruses or bacteria (germs) that stimulate the immune system at the"wrong" time in a patient with genetic background that puts them at riskfor this autoimmune disease. An example might be that some types ofthyroid disease are caused by problems with the immune system and asimilar autoimmune condition can cause MG.IV. MECHANISMS (Pathophysioloy/disease process)
V. PATHOLOGICAL CONSEQUENCES (Complications)omplications in MG arise late in the disease when larger muscle groups become involved.Dysphagia and dyspnea should raise red flags as these two symptoms may lead to respiratorycompromise and ultimately death.Myasthenic crises are exacerbation of symptoms cause be an aggravating factor. Myastheniccrises can be life-threatening. Aggravating factors include pregnancy, emotional stress,infections, excessive alcohol, UV light, extreme temperatures, thyroid disease and certainmedications. Medications such as chloroquine, quinidine, procainamide, prednisone, lithium,phenytoin, cisplatin, magnesium, statins, beta-blocker, calcium channel blockers, Botox,polymyxin, and aminoglycosides have been known to precipitate dormant MG and to triggermyasthenic crises.VI. DIFFERENTIAL DIAGNOSIS (Diagnostic evaluation)the differential diagnosis for MG is vast. Due to its variability in presenting symptoms, MG canmimick many diseases. It is important to remember that the presence of pupillary abnormalitesexcludes the diagnosis of MG.Lambert-Eaton Myasthenic Syndrome (LEMS) can be thought of as the opposite of MG.The clinical features in LEMS include proximal muscle weakness and hyporeflexia withimprovement of symptoms with repeated muscle stimulation. LEMS is caused by antibodiesdirected against presynaptic calcium channels. It is associated with small cell lung carcinoma.Since ptosis is the most common presenting symptom in MG, it is important to go through itsdifferential diagnosis. Ptosis is defined as margin to reflex diameter 1 (MRD 1) of less than 2mmor an asymmetry of more than 2mm between eyes. Normal palpebral fissure (PF) verticallength is about 9mm, a ptotic lid has a PF < 9mm. Myasthenia gravis with ptosis has anextensive differential diagnosis. This includes: an intracranial lesion, tumor, pituitary adenoma,aneurysm, fascicular lesion of CN 3, evolving CN 3 palsy, post-viral neuropathy, thyroiddisorders*, migraines, meningitis, Horners syndrome, levator aponeurosis, chronic progressiveexternal ophthalmoplegia (CPEO), and developmental myopathy of the levator palpebraesuperioris muscle.Diplopia is another common symptom. A variable pattern of diplopia without pupillaryinvolvement should bring MG to the top of your differential list.
* Thyroid eye disease occurs in conjunction with MG in up to 5% of patients.VII. MANIFESTATIONS AND SURVEILLANCEVIII. CLINICAL MANAGEMENTa. NursingEducational topics for outpatient self-care include medication management.Understanding the actions of the medications and taking them on schedule isemphasized, as are the consequences of delaying medication and signs andsymptoms of myasthenic and cholinergic crisis.• Myasthenic Crisis causes: undermedication, stress, infection• Signs and symptoms: negative seeing, swallowing, speaking, breathing• Treatment: administration of cholinergic agents as ordered• Cholinergic Crisis cause overmedication• Signs and symptoms: PNS, increased salivation risked for aspiration• Treatment: anticholinergic agents, atropine sulfate• Health teachings for energy conservation. To do this, the nurse can suggest thatfrequently used items (i.e. hygiene products, cleaning products, snacks) be kep oneach floor to minimize travel between floors.• Prevention and management of complications such as aspiration. To minimize therisk of aspiration, mealtimes should coincide with the peak effects ofanticholinesterase medication. Rest before meals is encouraged to reduce musclefatigue. Sit upright during meals, soft foods in gravy or sauces can be swallowedmore easily.• Health education for strategies to help with ocular manifestations. To preventcorneal damage when the eyelids do not close completely, the patient is instructedto tape the eyes closed for short intervals and to regularly instill artificial tears.b. Medical & SurgicalManagement of myasthenia gravis is directed at improving function and reducingand removing circulating antibodies. Therapeutic modalities include:• Administration of anticholinesterase• Medications and immunosuppressive therapy
• Plasmapheresis• ThymectomyIX. CONCEPTUAL MODELS/FRAMEWORK (Theories Applied)OREM’S GENERAL THEORY OF NURSINGOrem’s general theory of nursing in three related parts:- Theory of self care Theory of self care deficit Theory of nursing systemA. Theory of Self CareThis theory Includes: Self care – practice of activities that individual initiates and perform on their own behalf in maintaining life ,health and well being Self care agency – is a human ability which is "the ability for engaging in self care" -conditioned by age developmental state, life experience sociocultural orientation health and available resources Therapeutic self care demand – "totality of self care actions to be performed for some duration in order to meet self care requisites by using valid methods and related sets of operations and actions" Self care requisites - action directed towards provision of self care. 3 categories of self care requisites are- o Universal self care requisites o Developmental self care requisites o Health deviation self care requisitesX. CASE STUDIES – Case Analysisa. Case Title
Impending respiratoty failure Type 1 secodary to probable HAP impendingMyasthenia Gravis Crisis.b. Brief Intro of the CaseMyasthenia gravis (MG) is an autoimmune disorder resulting from the production of antibodiesagainst acetylcholine receptors leading to the destruction of the postsynaptic membrane at theneuromuscular junction. In the US there are about 18,000 people with MG. Myasthenia graviscrisis (MGC) is defined as any MG exacerbation necessitating mechanical ventilation. Mostpatients presenting with MGC have an identifiable risk factor. The diagnosis of MGC should besuspected in all patients with respiratory failure, particularly those with unclear etiology. Acutemanagement of MGC requires supportive general and ventilatory therapy and institution ofmeasures to improve the neuromuscular blockade. The latter includes plasma exchange or i.v.immunoglobulin, and removal of the offending trigger. The outcome of patients with MGC hasimproved significantly and the current mortality rate is about 4 to 8%.c. Patient’s ProfilePatient name Uy, E 59 y/o female from Caloocan City, single. Patient admitted lastaApril 25, 2012 andwascleard CV was pricate internist outside.Patient underwentsternotomy with thymomectomy the next day 4/26/2012.d. Patient’s HistoryPatient hadbaseline PFT’s prior to |Orwhich showed normal results.Cefuroximewasuse as prophylacticantibiotic. Patient was received on FM rebreather at 5-6 lpmvery comfortable no ptosis and stable vital signs. Patient wasplacedon DATon 24/7and tolerated feeding.Post-op days- patient still has CBS andno DOB.IV neostigminand hydrocortisone shifted back tooral. Patient was well post-op until yesterdaypatient noticedesay fatigability with occasional shortness ofbreath. On PE there wasa decreasedbreath sounds in the right lung field and CXR done which showedpoorrespiratory effort minimal pleural effusion night no infiltrates.CBC repeatedandshowed inc WBC 15-1 segmenters of 96-5 plt 425. Patient wasrefferedto Pulmoandincentive spirometry was advised.Today day 4 postop patient still complainedofsame shotness of breath and PE still decrease breath sounds patient was deckedto ICU for closemonitoring and observation.e. Assessment – Patient- centered
patient was diagnose with MG last February 2012 presenting ptosis oLeft eyelid andeasy fatigability and weakness of upper extrimities right morethan left (assymertic)upon continuos/ repetitive use( example writing) RNS done consistentwith MG conjuactional area). Mainly affectedor bicularis oculi and nasalis.f. Diagnostic exam – Results Onlyfinding were enlarged thymus 4x larger than normal size thymus. Left thymusattached to phrenic nerve.g. Pathophysiology – Patient – centeredh. Nursing Management – diagnosis,interventions,rationalei. Medical & Surgical ManagementXI. SELECTED RESEARCH – Literature MatrixXII. QUESTIONS FOR FUTURE STUDIESWhat is the best treatment algorithm and safest long-term management ofmyasthenia gravis? What patients are likely to benefit from thymectomy?How long should myasthenia gravis patients be treated? Is it possible to discontinueimmunotherapy once remission has been achieved? What are the risks associatedwith long-term immunosuppression? In this article, we review current therapeuticstrategies and these unresolved questions about myasthenia gravis treatment.