Resistance to thyroid hormone (RTH) describes a rare syndrome in which serum levels of thyroid hormones are elevated but serum levels of thyroid stimulating hormone (TSH) are unsuppressed. The importance of thyroid hormones for the normal function of the adult brain is corroborated by the frequent association of thyroid dysfunctions with neurological and psychiatric symptoms. In this study we investigated whether adult thyroid hormone resistance affects cortical excitability and modulates inhibitory and excitatory intracortical circuitries by using transcranial magnetic stimulation. Cortical excitability was probed with transcranial magnetic stimulation in 4 patients with thyroid hormone resistance, 10 patients affected by overt hypothyroidism (OH) and 10 age-matched healthy controls. We tested motor thresholds, motor evoked potential recruitment curve, cortical silent period (CSP), short interval intracortical inhibition (SICI) and intracortical facilitation. In both OH and RTH patients, the inhibitory cortical circuits were affected compared with euthyroid controls, but in opposite ways. In OH patients, CSP was prolonged and SICI was decreased. On the contrary, in RTH patients CSP was shortened and SICI was increased. Thyroid hormones may influence cortical excitability and cortical inhibitory circuits.

中文翻译：

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与甲状腺功能减退和甲状腺功能正常的患者相比，对甲状腺激素具有抗性的患者的皮质兴奋性：一项经颅磁刺激研究。

对甲状腺激素（RTH）的耐药性描述了一种罕见的综合征，其中甲状腺激素的血清水平升高，但甲状腺刺激激素（TSH）的血清水平未受到抑制。甲状腺功能障碍与神经和精神病症状的频繁关联证实了甲状腺激素对成人大脑正常功能的重要性。在这项研究中，我们研究了成年甲状腺激素抵抗是否会通过经颅磁刺激来影响皮层兴奋性并调节抑制性和兴奋性皮层内回路。经颅磁刺激探测了4名甲状腺激素抵抗患者，10名受到明显甲状腺功能减退症（OH）影响的患者和10名年龄匹配的健康对照者的皮层兴奋性。我们测试了马达阈值，运动诱发电位潜伏曲线，皮质沉默期（CSP），短时皮质内抑制（SICI）和皮质内促进。在OH和RTH患者中，与正常甲状腺对照组相比，抑制性皮质回路受到影响，但方式相反。在OH患者中，CSP延长而SICI降低。相反，在RTH患者中，CSP缩短而SICI增加。甲状腺激素可能会影响皮层兴奋性和皮层抑制回路。在RTH患者中，CSP缩短，SICI增加。甲状腺激素可能会影响皮层兴奋性和皮层抑制回路。在RTH患者中，CSP缩短，SICI增加。甲状腺激素可能会影响皮层兴奋性和皮层抑制回路。