Most of these patients come to an otolaryngologist for their nasal or pharyngeal symptoms.
Clinical presentation is as follows:
- Occular Symptoms: Ptosis, diplopia or both.
- Oropharyngeal, symptoms: Dysphagia, dysarthria, dyspnoea.
- Weakness of muscles of mastication and facial muscles.
- Nasal twang (nasal speech), nasal regurgitation and marked fatigue in articulation.
- Pharyngeal musculature weakness may cause dysphagia for liquids and solids.
- Laryngeal muscle weakness may cause dyspnea, dysphonia and hoarseness of voice and weak cough reflex.
- Involvement of respiratory muscle may cause respiratory striders.
It is based on a detailed history of the clinical course of the disease, clinical examination and laboratory investigation. The positive finding like ptosis, diplopia, facial weakness and progressive fatigue in chewing, swallowing and speaking. The diagnosis is confirmed by a positive neostigmine test.
The hysteria, disseminated sclerosis, bulbar lesions, and polymyositis do mimic the picture of myasthenia gravis and should be excluded by appropriate tests and laboratory investigations. It is also stressed that malignancy of oropharyngeal, nasopharyngeal spaces should be kept in mind in evaluating the diagnosis. The importance of positive neostigmine test is the main stay in the diagnosis of the myasthenia gravis.
- Most of these patients are well maintained on a regime of medical drugs.
- Neostigmine bromide 15 mg orally four times/day and may be increased upto 180 mg/day.
- Edrophonium chloride (Tensilon) 10 mg 1/v may relieve myasthenic weakness in 20 to 30 seconds. 25–30 mg 1/m daily gives relief for several hours.
- Ephenrine sulphate: 12 mg/day. The side effects of these drugs like abdominal cramps, nausea, vomiting may be prevented by adding an atropine like drug.
- Corticosteroids and corticotropine: Encouraging results have been reported. Taking alternative day steroids orally is the recommended therapy.
Myasthenia gravis with Thymus tumor can be subjected for Thymectomy in females under 40 years, where medical treatment has failed. Complete remission may occur in 1/3rd of patients. The surgical result in man is uncertain.
Deep X–ray therapy
Those patients whose medical treatment has failed and those who have refused surgery, may be subjected for deep X–ray therapy (3000 R) to thymus in 10 to 12 divided doses. Partial remission may occur in half the patients.
The Myasthenic crisis is an emergency and should be attended to immediately. Sudden inability to breath or swallow may occur any time. These patients should carry two ampules of 0.5 mg. of Neostigmine methysulphate to be given immediately S/c or 1/m if severe symptoms develop.
Progressive and potentially dangerous respiratory stridor may take place and will require immediate emergency tracheostomy. Therefore both, a tracheostomy oxygen and suction unit should be kept near the patient. If these facilities are not available, then the patient should be transferred to an intensive care unit for management where respirator facilities will be available. During this emergency treatment body fluids and electrolytes should be maintained.
As regards the prognosis of this condition, it is always guarded. The spontaneous remission occurs frequently but a relapse is the rule. Myasthenic crisis and sudden death may also occur. The most critical period following the onset is two years.
- Brumner N. G. (1972). ‘Corticosteroids in Myasthenia Gravis’. Neurology 22, COC.
- Cape C. A., Utterback R. A. (1973). ‘Maintenance of ARTH in Myasthenia Gravis’. New England Journal Med. 27,288.
- Kreal et al. (1967). ‘Role of Thymectomy in the management of Myasthenia Gravis’. Ann Surgery 165,111.
- Warmolts J. R., Engel W. K. (1972). ‘Benefit from alternate prednisone in Myasthenia Gravis’. New England J Med. 17,286.