|Year : 2014 | Volume
| Issue : 2 | Page : 68-69
Thyrotoxic bulbar myopathy: An unusual presentation of Grave's disease
P Baburaj, BV Shankara
Department of Medicine, Jubilee Mission Medical College and Research Institue, Thrissur, Kerala, India
|Date of Web Publication||31-Mar-2014|
XXVIII/524/3, Parameswara Nilayalm, West Palace Road, Thrissur - 680 020, Kerala (State)
Source of Support: None, Conflict of Interest: None
The most common manifestations of thyrotoxic neurological disease are in the form of myopathy. The muscles usually involved are proximal skeletal muscles. Bulbar myopathy is an uncommon presentation of Grave's disease. We are reporting a case of thyrotoxic bulbar myopathy.
Keywords: Grave′s disease, thyrotoxic bulbar myopathy, thyrotoxic neurological disease
|How to cite this article:|
Baburaj P, Shankara B V. Thyrotoxic bulbar myopathy: An unusual presentation of Grave's disease. Thyroid Res Pract 2014;11:68-9
| Introduction|| |
Neurological manifestations in thyrotoxicosis most commonly are in the form of myopathy. The muscles usually involved are proximal skeletal muscles. Recent studies performed show that as many as 67% patients complain of weakness and 80% patients have objective weakness in at least one muscle group. Bulbar myopathy is an uncommon presentation of thyrotoxicosis. Here, we are reporting one such uncommon presentation of thyrotoxicoxis.
| Case Report|| |
A 70-year-old male was admitted to our hospital with non-exertional palpitations, dysphagia, dysarthria and nasal tone of voice starting 4 weeks ago and now progressive dyspnea starting 2 weeks ago.
On examination, the patient was conscious and oriented. Clubbing was present. Periorbital edema noted, exophthalmos seen and lid lag present. Pretibial myxedema noted in both legs, more in right leg than left leg. The patient had pulse rate of 110/min, irregularly irregular and a blood pressure of 136/70 mm of mercury in the right upper limb in supine position; diffuse enlargement thyroid of with systolic bruit was present. Cardiovascular system examination showed: elevated jugular venous pressure by 10 cm, 'a' waves absent and irregular 'v' waves, mild cardiomegaly, varying intensity of heart sounds and ejection systolic murmur in third left sternal border. The respiratory system revealed bilateral basal crepitations. The central nervous system examination showed higher mental functions normal, proptosis present (axial length in Hertel's meter showed 21.5 mm in right eye and 22 mm in left eye), optic fundi normal and pupil normal. Patient had diminished eye movements in all directions. Bilateral palatal weakness was present and gag reflex was absent. Tongue flabby on palpation, bulk was normal, no wasting and no fasciculation. Tongue protrusion, side to side and all other tongue movements reduced.
Investigations on admission
Normocytic normochromic anemia; total count- 5230 cells/mm 3 , polymorphs-70%, lymphocytes-23%, eosinophils-4%, monocytes-3%; erythrocyte sedimentation rate - 62 mm/hr; blood urea - 32 mg/dl; serum creatinine- 1.1 mg/dl; serum calcium - 8.8 mg/dl; thyroid function test showed triiodothyronine (T 3 ) - 3.72 ng/ml (reference range, 0.80 - 2.0), thyroxine (T4) - 18.34 μg/ml (5.1-14.1), thyroid stimulating hormone (TSH)- <0.005 μIU/ml (0.27- 4.2); thyroid peroxidase antibody (TPO Ab) - 11.97 IU/ml (reference range < 35 IU/ml); urine routine -within normal limits (WNL); single fiber electronmyography (EMG) - WNL; magnetic resonance imaging (MRI) brain - WNL; technetium thyroid scan - thyroid enlarged, increased perfusion and trapping s/o Graves disease: MRI orbit - showed fatty infiltration and string like appearance of extraoccular muscles, sparing tendinous attachment at the ring of Zinn suggestive of Grave's ophthalmopathy
Considering the presentation of non-exertional palpitation, dyspahgia, dysarthia and nasal tone of voice, dyspnea, atrial fibrillation with congestive heart failure and diffuse goiter with ophthalmopathy, dermopathy, bulbar myopathy, elevated T3, T4 and very low TSH he was diagnosed to have Grave's disease with bulbar myopathy.
The patient was treated with carbimazole 40 mg, propronolol 50 mg, frusemide 40 mg and supportive measures. His cardiac failure improved, ventricular response to atrial fibrillation also improved. On follow-up bulbar myopathy is better.
| Discussion|| |
Grave's disease is associated with a variety of neurological symptoms and signs. , These are: Thyrotoxic myopathy, ,, neuropsychiatric manifestations - cognitive abnormalities and psychosis, persistent fine tremors of hands,  thyrotoxic hypokalemic periodic paralysis, ,, myasthenia gravis ,, and rare presentation thyrotoxic bulbar myopathy  as in our case.
The most common manifestation of thyrotoxic neurological disease is in the form of myopathy. ,, The muscles usually involved are proximal skeletal muscles. ,,, Recent studies performed show that as many as 67% patients complain of weakness and 80% patients have objective weakness in at least one muscle group. 
Myopathic symptoms occur after the onset of more typical thyrotoxic features. Males are affected to a greater degree than females.  The degree of weakness correlates with the duration of the thyrotoxicosis rather than the severity. Bulbar myopathy is an uncommon presentation of thyrotoxicosis. , There are several case reports describing bulbar myopthy as a presenting feature in thyrotoxicosis. However, acute bulbar myopathy also has been described in thyrotoxicosis. ,
The pathophysiology of myopathy in thyrotoxicosis is multifactorial: (1) Catabolic effect of thyroxin on muscle.  (2) Effect on transcription of genes controlling calcium regulatory proteins and myosin heavy chains. (3) Beta-2 adrenergic stimulation and cyclic adenosine monophhophate (cAMP) activation. (4) Increased substrate uptake but inefficient utilization leading to reduced adenosine triphophate (ATP) production and decreased muscle contractility.
Investigations in a case of thyrotoxic myopathy reveal: (1) Normal serum creatine kinase and serum myoglobin.  (2) Normal nerve conduction study.  (3) EMG - short duration motor unit potentials and increased frequency of polyphasic potentials.  (4) Light microscopy - normal or fiber atrophy [both type 1 and type 2], varying degrees of fatty infiltration, occasional fiber necrosis, glycogen depletion and lymphocytic infiltration. (5) Electron microscopy - elongated mitochondria,  decrease in the number of mitochondria, swelling of transverse tubules,  sacrolemmal glycogen deposition and papillary projections from the sarcolemma.
Treatment consists of treatment for thyrotoxicosis. ,, There is no specific treatment for thyrotoxic proximal myopathy and bulbar myopathy itself other than supportive management. ,, However most of the patients with thyrotoxicosis have complete resolution of myopathy in 3-6 months,  which was observed in our patient also.
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