6.5%甲狀腺毒症會有頭暈,但深入研究的文獻卻很有限。一50歲女性,罹患無預兆偏頭痛已經2年,因突發頭暈、手顫抖、畏光及畏聲求診於他院,診斷為甲狀腺毒症、高血壓及心搏過速,經保守治療1個月後,頭暈依然持續,遂求診於本院。理學檢查、前庭功能檢查及純音聽力檢查並無異常發現,但眼振電圖、溫差測試及前庭誘發肌性電位呈現異常。血管磁振造影顯示後方威利氏環不完整及後顱窩循環變異,擴散加權顯影與表面擴散係數分布圖呈現上腦幹後方之異常。可能是甲狀腺毒症刺激腦血管易發收縮,加上中樞神經之血管變異,造成暫時性的後顱窩循環血流不穩,引起上腦幹病變引發頭暈。接著,腦幹受傷後的電生理變化向上傳播引起畏光及畏聲等偏頭痛的症狀。建議停止抗眩暈劑及抗焦慮劑,鼓勵運動,減少臥床休息。爾後1個月,頭暈逐漸緩解。經過4個月的追蹤,情況依然穩定,病症未復發。
Overall, 6.5% of thyrotoxicosis patients seem to suffer from dizziness, but investigation in this area is limited in the literature. A 50-year-old female had been bothered with migraine without aura for two years. She suddenly presented with dizziness, hand tremor, photophobia and phonophobia. At this point, thyrotoxicosis with hypertension and tachycardia were diagnosed at a regional hospital. After one month of conservative treatment, the dizziness was still present. At our hospital, her physical examination, vestibular function test and pure tone audiometry were normal. However, an electronystagmogram, a caloric test and her vestibular evoked myogenic potential were abnormal. Magnetic resonance angiogram showed a defect of the posterior circle of Willis, and variation in the posterior circulation. Diffusion weighted imaging and an apparent diffusion coefficient map revealed a posterior abnormality of the superior brainstem. Thyrotoxicosis might predispose the central vascular system to easily constrict. Due to such a central vascular anomaly, dizziness will occur as a result of the pathological changes to the upper brainstem and are secondary to the transient posterior circulation insufficiency. After the brainstem was injured, the electrophysiological changes spread upward and induced the migrainous symptoms including photophobia and phonophobia. Based on these results, anti-vertigo and anti-anxiety treatments were ceased and, in addition, more outside exercise and less bed rest were recommended. Over the following one month, the dizziness subsided gradually and the next four months were uneventful and there has been no recurrence.