Excitability of the motor cortex during ovulatory and anovulatory cycles: a transcranial magnetic stimulation study.
OBJECTIVE
The pathophysiology of catamenial diseases such as epilepsy is unclear. Therefore, we investigated changes in cortical excitability during anovulatory and ovulatory cycles.


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.
Hattemer
Katja
K
Department of Neurology, University of Marburg, Germany. hattemer@med.uni-marburg.de
Knake
Susanne
S
Reis
Janine
J
Rochon
Justine
J
Oertel
Wolfgang H
WH
Rosenow
Felix
F
Hamer
Hajo M
HM
D000328:Adult; D000704:Analysis of Variance; D000858:Anovulation / Q000097:blood / Q000503:physiopathology*; D001927:Brain Diseases / Q000097:blood / Q000503:physiopathology; D016022:Case-Control Studies; D004958:Estradiol / Q000097:blood; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008597:Menstrual Cycle / Q000502:physiology; D009044:Motor Cortex / Q000503:physiopathology*; D011374:Progesterone / Q000097:blood; D018709:Statistics, Nonparametric; D050781:Transcranial Magnetic Stimulation
D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone