The cause of the myasthenia gravis is not known, but it is said to be a metabolic disorder. Thymus gland abnormalities have been described in some patients. It has also been said that myasthenia gravis is an auto immune disease, since multiple auto antibodies have been found in the sera of patients of this disorder. The women are more often affected than men and the disease appears between 20 and 40 years of age.
About 20 cases of proved myasthenia gravis were being treated at a hospital in Pune since 1970. Out of this, three patients required thymectomy, two patients went into respiratory failure and had to be subjected for tracheotomy and were subsequently put on the respirator. They died ultimately. Fourteen cases were managed on medical therapy e.g. neostigmine, alternate day steroids and supportive therapy.
Three interesting cases which were presented to our department are given below. The patients were diagnosed for oropharyngeal complaints like dysphagia, dyspnoea, dysphonia, hoarseness, diplopia and ptosis, mimicking the presentation of bulbar palsy, cricopharyngeal and nasopharyngeal malignancies, with neurological involvements.
A 40 year old man complaining of difficulty in swallowing, heaviness of speech and inability to open his eye, was referred by his practitioner to ENT OPD as the symptoms were rapidly progressing. The detailed examination of his nose, pharynx, nasopharynx and larynx did not reveal any abnormality except weak movements of palate (soft), pharyngeal wall and vocal cords. There was no evidence of any malignancy either.
Routine blood, urine, X–ray chest, ECG and lipid profiles were within normal limits. The only positive findings were ptosis, diplopia and marked fatigue. The nasal regurgitation was dysarthric and the patient had difficulty in swallowing even liquids. A provisional diagnosis of Myasthenia gravis was made and confirmed by a positive neostigmine test.
A 40 year old female was admitted for difficulty in breathing, hoarseness of voice and difficulty in swallowing. A routine ENT examination was done. Her nose, nasopharynx and larynx looked normal except for weakness in palatal movements, pharyngeal musculature and sluggish mobility of the cords. She had ptosis though diplopia and fundi were normal. Routine blood, urine and serum electrolyte studies did not reveal any abnormality. An X–ray of the chest revealed huge shadows in the mediastinum suggestive of thymoma. Provisional diagnosis of myasthenia gravis was confirmed by positive neostigmine test.
A 35 year old female was attending an ENT clinic for slurring of speech, nasal regurgitation and change of voice for six weeks. She would feel fine in the mornings, but as the day advanced, the symptoms would progress and at the end of the day, she would become dyspneic and dysphonic with marked fatigue in articulation.
A routine ENT examination did not reveal any marked abnormality except weakness in palatal movements, nasal twang, and weak movements of vocal cords. Even routine hemogram, urine and chest X–ray did not reveal any abnormality. A provisional diagnosis of myasthenia gravis was made and confirmed by a positive neostigmine test.