title: Cortical excitability in patients with resistance to thyroid hormone compared to patients with hypothyroidism and euthyroid controls: a transcranial magnetic stimulation study.
abstract: 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.
authors.forename: C
authors.initials: C
authors.lastname: Terranova
authors.forename: V
authors.initials: V
authors.lastname: Rizzo
authors.forename: A
authors.initials: A
authors.lastname: Calamuneri
authors.forename: L
authors.initials: L
authors.lastname: Bartolone
authors.forename: F
authors.initials: F
authors.lastname: Morgante
authors.forename: D
authors.initials: D
authors.lastname: Bruschetta
authors.forename: V
authors.initials: V
authors.lastname: Roberto
authors.forename: P
authors.initials: P
authors.lastname: Girlanda
authors.forename: S
authors.initials: S
authors.lastname: Benvenga
authors.affiliation: Department of Biomedical Science and Morphological and Functional Images, University of Messina, Italy - Email: aquartar65@gmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Quartarone
mesh_terms: D000071080:Cortical Excitability; D004576:Electromyography; D019054:Evoked Potentials, Motor; D006801:Humans; D007037:Hypothyroidism; D009044:Motor Cortex; D009433:Neural Inhibition; D013963:Thyroid Hormones; D050781:Transcranial Magnetic Stimulation
chemical_list: D013963:Thyroid Hormones