title: Menstrual cycle dependent right-to-left shunting: a single-blinded transcranial Doppler sonography study.
abstract: 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.
authors.affiliation: Department of Neurology, University Hospital Innsbruck, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Klien
authors.forename: M
authors.initials: M
authors.lastname: Spiegel
authors.forename: K
authors.initials: K
authors.lastname: Engelhardt
authors.forename: C
authors.initials: C
authors.lastname: Schmidauer
authors.forename: H
authors.initials: H
authors.lastname: Ulmer
authors.forename: M
authors.initials: M
authors.lastname: Diepers
authors.forename: E
authors.initials: E
authors.lastname: Schmutzhard
authors.forename: T
authors.initials: T
authors.lastname: Mutzbauer
mesh_terms: 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
chemical_list: D004967:Estrogens