Myasthenia Gravis NEUROLOGICAL DISORDER

Compiled By: Mr. Ashish Roy

1. MYASTHENIA GRAVIS Compiled By- Mr. Ashish Roy (Nursing Tutor)

2. Introduction of mg Myasthenia Gravis is a neuromuscular disease characterized by considerable weakness and abnormal fatigue of the voluntary muscles. A defect in the transmission of nerve impulses at the myoneural junction occurs. Causes include insufficient secretion of acetylcholine, excessive secretion of cholinesterase, and unresponsiveness of the muscle fibers to acetylcholine.

3. MYASTHENIA GRAVIS Myasthenia gravis is a chronic autoimmune disorder affecting the neuromuscular transmission of impulses in the voluntary muscles of the body. It is due to an antibody-mediated attack against acetylcholine receptors at the neuromuscular junction. OR MG, is 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 causes damage to them. MG is often associated with thymic tumors.

4. Etiological Factors/Causes Exact cause is un-known Sex & age: Women tend to develop the disease at an earlier age (20 to 40 years of age) compared to men (60 to 70 years of age), and women are affected more frequently. Thymus gland abnormalities are associated with 80% of MG patient Found to be associated with auto immune disorders like Thyroid disease, rheumatoid arthritis

5. PATHOPHYSIOLOGY Due to etiological factors thymus tumor etc.( thymus gland is the site of antibody production) autoantibodies directed at the acetylcholine receptor sites damage the receptors Fewer receptors are available for stimulation Impaired transmission of impulse across myoneuronal junction Voluntary muscle weakness increase with activity

6. Clinical Manifestations / Clinical Features / Signs & Symptoms Extreme muscular weakness and easy fatigability. Vision disturbances: diplopia and ptosis ( drooping eyelid, blepharoptosis ) from ocular weakness Facial muscle weakness causes a masklike facial expression. Dysarthria and Dysphagia from weakness of laryngeal and pharyngeal muscles Proximal limb weakness, with specific weakness in the small muscles of the hands. Respiratory muscle weakness can be life-threatening. Assessment Weakness and fatigue Difficulty chewing Dysphagia Ptosisptosis Diplopia Weak, hoarse voice Difficulty breathing Diminished breath sounds Respiratory paralysis and failure

7. Diagnostic Evaluation Serum test for acetylcholine receptor ( AChR ) antibodies : positive in up to 90% of patients. Edrophonium ( Tensilon ) test : I.V. injection relieves symptoms temporarily. After injection, a marked but temporary improvement in muscle strength suggests myasthenia gravis. It also differentiates myasthenic crisis from cholinergic crisis. Thirty seconds after injection, facial muscle weakness and ptosis should resolve for about 5 minutes. This immediate improvement in muscle strength after administration of this agent represents a positive test and usually confirms the diagnosis. Electrophysiologic (EMG) testing : reveals decremental response to repetitive nerve stimulation. CT (Computed tomography) scan to assess enlargement of thymus gland.

8. Injection of edrophonium ( Tensilon ) is used to confirm the diagnosis (have atropine available for side effects). Improvement in muscle strength represents a positive test and usually confirms the diagnosis. MRI may demonstrate an enlarged thymus gland. Test includes serum analysis for acetylcholine receptor and electromyography (EMG) to measure electrical potential of muscle cells.

9. COMPLICATIONS Aspiration Respiratory failure Complications of decreased physical mobility Brittle crisis occurs when the receptors at the neuromuscular junction become insensitive to anticholinesterase medication( Acetylcholinesterase is the enzyme that is the primary member of the cholinesterase enzyme family. An acetylcholinesterase inhibitor is the inhibitor that inhibits acetylcholinesterase from breaking down acetylcholine into choline and acetate, thereby increasing both the level and duration of action of the neurotransmitter acetylcholine in the central nervous system, autonomic ganglia and neuromuscular junctions, which are rich in acetylcholine receptors. Acetylcholinesterase inhibitors are one of two types of cholinesterase inhibitors ). EXAMPLE- Reminyl ( galantamine ), Aricept ( donepezil), Neostigmine ( neostigmine), Mestinon ( pyridostigmine ), Elexon ( rivastigmine ). Myasthenic crisis Cholinergic crisis

10. MYASTHENIC CRISIS It is the exacerbation of the disease process charactarized by severe generalized weakness, respiratory failure and dysphagia. Sudden respiratory distress. Signs of dysphagia , dysarthria , ptosis , and diplopia . Tachycardia, anxiety. Rapidly increasing weakness of extremities and trunk.

11. CHOLINERGIC CRISIS It due to anticholinesterase overmedication may mimic the symptoms of exacerbation. The signs of cholinergic crisis are Nausea, vomiting and diarrhea Muscular cramps and fasciculation Increased salivation profuse sweating and pallor Small pupils Increased bronchial secretion Muscle and respiratory paralysis

12. MANAGEMENT Oral anticholinesterase drugs, such as neostigmine and pyridostigmine are first-line treatment for mild myasthenia gravis, enhancing neuromuscular transmission. Immunosuppressive drugs, such as prednislone Azathioprine ( Imuran ) may be added as a steroid-sparing agent. Immunosuppressant treatment is often permanent. Plasmapheresis removes antibodies from the blood and is used for patients in myasthenic crisis. Thymectomy for those people with tumor or hyperplasia of the thymus

13. INTERVENTIONS FOR MYASTHENIC CRISIS Immediate hospitalization and may require intensive care Edrophonium ( Tensilon ) to differentiate crisis and treat myasthenic crisis. represents a positive test and usually confirms the diagnosis. Atropine 0.4 mg should be available to control the side effects of edrophonium , which include bradycardia, sweating, and cramping Airway management mechanical ventilation Neostigmine ( Prostigmin ) I.V. for myasthenic crisis

14. NURSING MANAGEMENT

15. Nursing Diagnoses Fatigue related to disease process Risk for Aspiration related to muscle weakness of face and tongue Impaired physical mobility related to muscle weakness Self care deficit related to muscle weakness Social Isolation related to diminished speech capabilities and increased secretions

16. NURSING INTERVENTIONS Monitor respiratory status and ability to cough and deep breathe adequately. Monitor for respiratory failure. Maintain suctioning and emergency equipment at the bedside. Monitor vital signs. Monitor speech and swallowing abilities to prevent aspiration. Encourage the client to sit up when eating. Assess muscle status. Instruct the client to conserve strength. Plan short activities that coincide with times of maximal muscle strength. Monitor for myasthenic and cholinergic crises. Administer anticholinesterase medications as prescribed. Instruct the client to avoid stress, infection, fatigue, and over-the counter medications. Instruct the client to wear a Medic-Alert bracelet. Inform the client about services from the Myasthenia Gravis Foundation.

17. Documentation Guidelines Respiratory status: Rate, quality, depth, ease, breath sounds, arterial hemoglobin saturation with oxygen Ability to chew, swallow, and speak (swallowing can be subjectively rated by the patient in anticipating ability to swallow food [0 =unable to swallow liquids to 5 = able to swallow regular diet]), food intake, daily weights Muscle weakness and strength, speed and degree of fatigue, ability to perform activities of daily living, response to rest, and plans for modification of activity Ptosis (can be rated by the nurse [0 = unable to open lid to 5 =uppermost edge of iris visible])

18. Discharge and Home Healthcare 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.

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