Keywords:
Basal ganglia calcification, Graves’ disease, Hyperthyroidism, thyroid disease.
Abstract :
Basal ganglia calcifications have been linked to a wide range of causes. Mostly it is an idiopathic finding, especially in elderly. Endocrinological and neurological disorders are major causatives. Hyperthyroidism was not related to this finding. We present a case of incidental basal ganglia calcification in man with Grave’s disease.
Introduction :
Basal ganglia calcifications (BGCs) have been linked to a variety of endocrinological and neurological conditions, it is also a frequent incidental finding in imaging studies with again (1). Bilateral BGCs might also reflect calcium metabolism disorders, intoxication, and autoimmune and genetic diseases (2). It can be categorized into primary and secondary brain calcifications. Among secondary calcifications, parathyroid disorders are the most common. Infections are another reason for intracerebral calcifications (1).
Graves’ disease, an autoimmune thyroid gland disorder is considered the most common cause of hyperthyroidism and thyrotoxicosis, it includes goiter, exophthalmos, and pretibial myxedema if fully expressed. (3)
The occurrence of Graves’ disease with bilateral BGCs has never been reported in the literature. Here we present a case of a young patient who presented with lower limb weakness and thyrotoxicosis to be diagnosed later as Graves’ disease with thyrotoxic periodic paralysis and a CT scan showing bilateral BGCs. Our case suggests a pathological correlation.
Case presentation :
A 27-year-old Filipino man with no known chronic illnesses presented to the Emergency Department (ED) complaining of acute bilateral leg weakness that started 2 hours prior to coming to ED. He also had some weakness in his arms but was less in severity. The patient denied any pain or numbness. He mentioned a history of weight loss of 5kg during the past month.
Vital signs were normal apart from tachycardia 117/minute. Physical examination revealed muscle power 4/5 in both upper limbs, 3/5 in both lower limbs, and diffuse goiter. ECG demonstrated sinus tachycardia. Given the acute onset of the weakness, head computed tomography was done to rule out stroke, however, it showed Bilateral basal ganglia and dentate nuclei calcifications Figure (1). Blood tests were remarkable for high FT4 >100 mIU/L (11.0- 23.3), low TSH< 0.01 mIU/L (0.30-4.20), low potassium level =3 mmol/L (3.5-5.3), and high TSH receptor antibodies (TRAP).
The patient was diagnosed with Thyrotoxic periodic paralysis with Graves’ disease. He improved dramatically after intravenous potassium replacement. He has been started on Carbimazole 20 mg twice per day and propranolol 40 mg twice per day.
Further workup showed normal levels of calcium, phosphorus, and basal metabolic panel. The patient had no remarkable central nervous system infections in the past, no exposure to lead or other heavy metals, and his family history was irrelevant. All in all, the suspicion of a potential association between Graves’ disease and basal ganglia calcification was raised.
Discussion :
Basal ganglia calcification has been reported in 15-20% of the population, mainly in patients over 65 years. (4) This radiological finding is also known as Fahr’s disease, a rare inherited or sporadic neurological disorder, with an age of onset around the fourth to the fifth decade presented with a movement disorder or/and neuropsychiatric manifestations. However, differential diagnosis is wide in the case of basal ganglia calcifications which include primary and secondary categories. (5) Primary or idiopathic refers to the presence of radiological findings in the absence of clinical symptoms or metabolic and electrolyte panel disturbances (6). Secondary basal ganglia calcification has been reported in relation to endocrinological and neurological disorders. Parathyroid abnormalities were the most common underlying pathology due to abnormality in calcium/phosphor balance which leads to generalized calcification and basal ganglia were reported as one of the possible locations. In 1980 an article published by Chad R. Cohen et al categorized secondary causes into four main categories; endocrine causes that include hypoparathyroidism, pseudohypoparathyroidism, pseudo-pseudohypoparathyroidism, Congenital/ Developmental, inflammatory, and toxic, they concluded that any calcification in the basal ganglia, dentate nucleus, multiple areas in the cortex in a patient of any age should be considered as pathological, while calcification in globus pallidus is considered pathological in patients under 40 years, it is physiological findings in patients more than 40 years (7). MG Harrington et al included hypothyroidism among the possible reasons for this radiological finding (8). Another article reported bilateral striocerebellar calcification associated with Hashimoto’s disease, although the mechanism is not clear, the deposits included mucopolysaccharide colloid material which might raise suspicion for a relation between both entities (9). In our case, the patient came with muscle weakness with low potassium levels and laboratory tests revealed the presence of thyrotoxicosis with later positive TSH receptor antibodies (TRAB) which confirmed the diagnosis of Graves’ disease. No abnormalities in calcium, phosphorus, or parathyroid hormone (PTH) were found. We could not find any reports suggesting a correlation between basal ganglia calcification and hyperthyroidism in general and Graves’ disease in specific. We report the first case that suggests this correlation. The early age of our patient and absence of any family history of a neuropsychiatric disorder or similar findings, the absence of any infections, travel history, or toxic exposure support the correlation in our patient.
Conclusion :
Although many disorders were related to intracranial calcifications. Basal Ganglia calcifications are most associated with endocrinological causes. Parathyroid disorders were a well-reported entity in the context of this radiological finding however thyroid disorder especially hyperthyroidism was not reported before. We suggest that Graves’ disease might be associated with bilateral basal ganglia calcification.