Abstract
We report three cases of thyrotoxicosis who presented acutely with headache to our neurology service in a 1-year period. In two of these patients there was a pre-existing or subsequent history of migraine. With hindsight, there were other clinical features of thyrotoxicosis but this diagnosis had been missed in primary care. Severe headache can be a striking presenting feature of thyrotoxicosis, but these cases provide reassurance to the clinician that when this does occur, other clinical features of hyperthyroidism are usually present.
Keywords
Introduction
Although both hyperthyroidism and hypothyroidism are recorded by the International Headache Society as causes of headache, there is little information about this clinical relationship. We report three adults, seen in a 1-year period, who presented acutely to our neurology service with headache as the presenting symptom of thyrotoxicosis.
Case reports
Case 1
A 34-year-old woman was referred urgently by her primary care physician with a 3-week history of severe generalized headache associated with nausea. This headache was a constant pain without throbbing, photophobia, phonophobia or osmophobia and unaffected by posture. She had a history of migraine without aura 10 years previously but no family history of migraine. Computed tomography of the brain and lumbar puncture were normal. She was given a discharge diagnosis of migraine but her symptoms failed to resolve. On further questioning, she reported insomnia, palpitations, dyspnoea and was feeling hot and shaky. She had a sinus tachycardia, rate 120 beats/min, bilateral fine hand tremor, a smooth diffuse goitre and brisk reflexes. Free thyroxine (T4) was 133 pmol/l [reference range (RR) 9–24], thyroid-stimulating hormone (TSH) <0.05 mU/l and the thyroid receptor antibody (TRAB) level was 21.1 IU/l (RR 0–1.5) confirming Graves' disease. After taking propanolol 40 mg tds and carbimazole 60 mg daily, her headache settled within 24 h, although her intermittent mild migraine without aura recurred.
Case 2
A 51-year-old woman was referred urgently with a 10-day history of transient right-sided facial numbness and visual disturbance and 2 months of unremitting occipital headache. The headache was a constant pain without throbbing, photophobia, phonophobia or osmophobia and unaffected by posture. There was no personal or family history of migraine. On direct questioning, she described nausea, diarrhoea and dizziness. She had developed thyrotoxicosis at the age of 38 years and had been treated twice with carbimazole, most recently stopped 6 months previously, with normal thyroid function measured 2 months previously. She was anxious and sweaty with a fine hand tremor. Neurological examination was normal. Her free T4 was 134 pmol/l, TSH < 0.05 mU/l and the TRAB level was 10.2 IU/l, confirming the diagnosis of Graves' disease. She restarted carbimazole and became headache free within weeks.
Case 3
A 20-year-old woman was referred urgently with a 10-week history of severe generalized headache, unrelieved by oral analgesia accompanied by nausea, vomiting, diarrhoea, weight loss, a constant feeling of ‘shakiness’ and intermittent dyspnoea, panic and sweating. The headache was a constant pain without throbbing, worse at night and lying down and not associated with photophobia, phonophobia or osmophobia. She had had amenorrhoea for 8 months. There was no prior personal or family history of migraine. She was tachycardic (120 beats/min) with marked tremor and a diffuse goitre. Neurological examination was normal. Free T4 was 61 pmol/l, TSH < 0.05 mU/l and the TRAB level was 4.4 IU/l. Following treatment with carbimazole for 12 months, her daily headache settled, but she continued to have frequent migraine without aura. She was also intermittently thyrotoxic, probably because of reduced compliance. Following thyroid surgery her migraines have remitted completely.
Discussion
We have described three patients referred urgently to neurology by their general practitioners because of new-onset headache due to thyrotoxicosis caused by Graves' disease. In none of the cases had the possibility of thyrotoxicosis been raised by the referring doctor, although, with hindsight, there were features other than headache to suggest this diagnosis. In all cases the headache had an unremitting quality and was not associated with sensory sensitivity. The headache improved in each case following treatment of the thyrotoxicosis, although in case 1 it could be argued that this was aided by treatment with propanolol.
Although headache appears on lists of symptoms reported in thyroid dysfunction, there are only sporadic reports of it as the presenting feature of hypothyroidism (1) or hyperthyroidism (2). In the International Headache Society Classification, headache due to hypothyroidism (but not hyperthyroidism) has its own category (3). Whilst some studies have suggested that thyroid abnormalities are common enough in chronic daily headache to warrant screening (4), other studies have failed to support this idea (5, 6). The notion that hyperthyroidism may exacerbate migraine seems logical and may be relevant in cases 1 and 3 (7). The fact that all three of these cases had Graves' disease may have been a coincidence, but is perhaps worthy of note. Further studies are needed to clarify whether there is any need to test thyroid function routinely in patients with new-onset headache, but clinicians should be aware of the association and have a low threshold for checking thyroid function.