Menstrual cycle dependent right-to-left shunting: a single-blinded transcranial Doppler sonography study.
OBJECTIVE
Menstruation has been described as risk factor for neurological decompression sickness in divers. In considering this for paradoxical gas embolism, we hypothesized that there may be a link between cycle-dependent hormonal changes and the manifestation of a right-to-left shunt (RLS).


METHODS
40 women with a regular cycle of 28 days underwent transcranial Doppler sonography examinations (TCD) on day 1 and on day 15 of the menstrual cycle. Cerebral high intensity transient signs (HITS) proved a RLS.


RESULTS
We found a 25% RLS incidence consistent with the literature. In 7 of 10 shunt-positive women it was detected mainly or exclusively on day 15. This difference in PFO detection rate is statistically significant (p = 0.031), indicating more RLS during the peri-ovulatory period.


CONCLUSIONS
Our results do not support menstruation as a risk factor for neurological decompression sickness. The peri-ovulatory estrogen peak, which leads to systemic vasodilation, may explain our data. Factors that increase the risk for developing a RLS and thereby paradoxical embolism should be avoided, perhaps including diving during the peri-ovulatory period of the menstrual cycle. Furthermore, contrast PFO testing in fertile females may be most sensitive if conducted mid-cycle.
Klien
S
S
Department of Neurology, University Hospital Innsbruck, Austria.
Spiegel
M
M
Engelhardt
K
K
Schmidauer
C
C
Ulmer
H
H
Diepers
M
M
Schmutzhard
E
E
Mutzbauer
T
T
D000293:Adolescent; D000328:Adult; D018592:Cross-Over Studies; D004242:Diving / Q000009:adverse effects / Q000502:physiology; D019320:Embolism, Paradoxical / Q000209:etiology; D004967:Estrogens / Q000097:blood; D005260:Female; D006344:Heart Septal Defects, Atrial / Q000097:blood / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008597:Menstrual Cycle / Q000097:blood / Q000502:physiology*; D008598:Menstruation / Q000097:blood / Q000502:physiology; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology; D010060:Ovulation / Q000097:blood; D011446:Prospective Studies; D012039:Regional Blood Flow; D012307:Risk Factors; D016037:Single-Blind Method; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods; D014636:Valsalva Maneuver
D004967:Estrogens