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Excitability of the motor cortex during ovulatory and anovulatory cycles: a transcranial magnetic stimulation study
Author(s) -
Hattemer Katja,
Knake Susanne,
Reis Janine,
Rochon Justine,
Oertel Wolfgang H.,
Rosenow Felix,
Hamer Hajo M.
Publication year - 2007
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.2007.02744.x
Subject(s) - transcranial magnetic stimulation , medicine , silent period , analysis of variance , anovulation , endocrinology , motor cortex , repeated measures design , stimulation , insulin resistance , statistics , mathematics , polycystic ovary , insulin
Summary Objective The pathophysiology of catamenial diseases such as epilepsy is unclear. Therefore, we investigated changes in cortical excitability during anovulatory and ovulatory cycles. Patients and methods Using transcranial magnetic stimulation (TMS), eight healthy women were investigated during anovulatory and 12 during ovulatory cycles. On days 8, −14, −7 and 2 of the cycle, resting motor threshold (RMT), cortical silent period (CSP), intracortical inhibition (ICI) and intracortical facilitation (ICF) were investigated. Repeated‐measures analysis of variance ( anova ) and nonparametric methods were used for statistical analysis. Results A trend was seen for group by phase interaction regarding ICI ( F = 2·5, P = 0·10). ICI varied during anovulatory cycles (median: 51·0% on day 8; 45·3% on day −14, 51·0% on day −7, and 28·6% on day 2; P = 0·040), mainly because of an increased inhibition on day 2. ICI was more pronounced in anovulatory cycles on day −14 ( P = 0·021), −7 ( P = 0·048) and 2 ( P = 0·018) compared to ovulatory women who did not show intraindividual changes ( P = 0·56). RMT, CSP and ICF showed no significant changes during anovulatory or ovulatory cycles. Conclusions The results suggest fluctuations in cortical excitability during anovulatory cycles, possibly due to the withdrawal of ‘excitatory’ oestrogens that initiate menses in anovulatory cycles.