title: Brain motion in patients with skull defects: B-mode ultrasound observations on respiration-induced movements.
abstract: BACKGROUND
  Since ancient times, brain motion has captured the attention of human beings. However, there are no reports about morphological changes that occur below the cortex or skin flap when a patient, with an open skull breathes, coughs, or engages effort. Thus, the aim of this study was to characterize brain motion caused by breathing movements in adults with an open skull.
  
  
  METHODS
  Twenty-five craniectomized patients were studied using B-mode ultrasonography during early and late postoperative periods. Twelve patients were analysed during surgery. Brain movements induced by breathing activity were assessed in this prospective observational study.
  
  
  RESULTS
  Taking as a reference the cranial base, an increase in intrathoracic pressure was accompanied by a rise of the brain due to the expansion of the basal cisterns. Greater increases in intrathoracic pressure (resulting from the Valsalva manoeuvre and coughing) propelled the brain in a block from the foramen magnum towards the craniectomy, mainly in structures near the tentorial incisure. Prolonging the Valsalva manoeuvre also resulted in thickening of the cortical mantle attributable to vascular congestion. The magnitude of these movements was directly related to breathing effort.
  
  
  CONCLUSIONS
  The increase in intrathoracic pressure was immediately transmitted to the brain by the rise of cerebrospinal fluid, while brain swelling attributable to vascular congestion showed a brief delay. The Valsalva manoeuvre and coughing caused abrupt morphological changes in the tentorial hiatus neighbouring structures because of the distension of the basal cisterns. These movements could play a role in the pathophysiology of the syndrome of trephined.
authors.affiliation: Neurosurgery Unit, "Dr. Abraham Piñeyro" Hospital, Arenales 361, 6000, Junin, Argentina, napicard@yahoo.com.
authors.forename: Nelson A
authors.initials: NA
authors.lastname: Picard
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Zanardi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D004453:Echoencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D011446:Prospective Studies; D012119:Respiration; D012886:Skull / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014636:Valsalva Maneuver / Q000502:physiology; D055815:Young Adult