FRI474 Panhypopituitarism And Central Hypothyroidism Presenting As Myoclonus And Hyperreflexia, An Unusual Presentation Likely Related To Thyrotropin-releasing Hormone

Abstract

Abstract Disclosure: I. Nadeem: None. W.J. Khan: None. S. Thapa: None. Introduction: Panhypopituitarism may present with symptoms of predominantly one or more hormonal deficiencies. The thyrotropin-releasing hormone has been described as causing neuromuscular hyperexcitability via its modifying role in synaptic functions in addition to its effect on the pituitary. We present a panhypopituitarism due to macroadenoma presenting with weakness, tongue fasciculation, hyperreflexia, and myoclonic jerks. Case Presentation: A 78-year-old woman with a medical history of essential hypertension came to ER with generalized weakness, twitching of her tongue, and involuntary jerking movements of her lower limbs for the past month. On admission, vital signs were normal. Neurological examination revealed tongue fasciculation and bilateral lower extremity myoclonus. Her visual field testing was normal. CT scan of the head showed an apparent seller mass but ruled out any acute pathology. Further neurologic, infectious, and rheumatologic work-up revealed negative results. In addition, an MRI of the cervical, thoracic, and lumbar spine was negative for any mass effect. The pituitary showed a 2.0 x 1.5 x 2.3 cm sellar mass, deforming the optic chiasm and deviating the infundibular stalk to the right side. Laboratory work-up revealed secondary adrenal insufficiency, central hypothyroidism, hypogonadotropic hypogonadism, and hyperprolactinemia. The patient was diagnosed with non-functioning pituitary macro adenoma. Myoclonus significantly improved after initiating the hormone replacement with levothyroxine and a stress hydrocortisone dose, gradually tapered to a physiological dose, and cabergoline. Repeat MRI after three months showed a stable 1.5 x 2.0 x 2.3 cm sellar mass. Surgery was not recommended due to no visual compromise. Instead, she will be followed in the clinic with a 6-month head imaging and hormone testing. Discussion: Usual clinical manifestations of hypothyroidism are the same regardless of etiology. However, there may be additional findings related to hypothalamic or pituitary dysfunction in the case of secondary or tertiary hypothyroidism due to non-thyroidal illness. Muscle fasciculations are common with hypothyroidism. But myoclonus and hyperreflexia are the findings in hyperthyroidism except for one hypothyroid state, i.e., Hashimoto encephalopathy (HE). TRH plays an important role in the pathophysiology of myoclonus and hyperreflexia in patients with HE and without HE. Our patient had tertiary hypothyroidism with likely elevated TRH in the presence of low FT4 and TSH. Therefore, we propose a high level of TRH in central hypothyroidism as the reason for her hyperreflexia and myoclonus. Presentation: Friday, June 16, 2023