Subject(s)
Decompressive Craniectomy , Hydrocephalus/surgery , Lymphangioma, Cystic , Brain , Drainage , Humans , HydrodynamicsABSTRACT
Human brain undergoes two different kinds of movements: subtle pulsatile ones associated with the cardiac cycle and others of a greater magnitude related to breathing activity. These motions constitute a pumping force for the circulation of cerebrospinal fluid (CSF). Moreover, brain motion (BM) plays a fundamental role as a driving force for the interstitial and CSF flow of tracers. We hypothesize that BM is more than a mere consequence of cardiac and respiratory activities; that it would be part of a fundamental physiological mechanism by propelling the interstitial flow of messengers, a mechanism also known as 'non-synaptic transmission' or 'volume transmission' (VT). Intracranial hypertension (ICH), a frequent complication of severe head trauma, is related to brain stiffness. Under this circumstance, not only brain perfusion could be at risk, but BM could be engaged as well. Decompressive craniectomy, presently indicated to reduce ICH refractory to medical treatment, could play a role in helping BM and VT. Once brain swelling is overcome, the closure of the cranial bone defect would ensure the recovery of the spatial and temporal patterns of BM. We discuss evidence supportive of the necessary role of a minimal and sequential BM for an adequate VT.
Subject(s)
Brain/physiology , HumansABSTRACT
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.
Subject(s)
Echoencephalography , Movement/physiology , Respiration , Skull/diagnostic imaging , Adolescent , Adult , Aged , Blood Pressure/physiology , Female , Humans , Male , Middle Aged , Prospective Studies , Skull/physiopathology , Valsalva Maneuver/physiology , Young AdultABSTRACT
Objetivo: evaluar los movimientos del parénquima encefálico durante la maniobra de Valsalva y la tos en pacientes craniectomizados y discutir sus implicancias fisiopatológicas y terapéuticas. Material y método. Catorce pacientes adultos con craniectomías mayores de 30 cm2 y colgajos pulsátiles fueron estudiados ecográficamente. La atención se focalizó en los cambios morfológicos intracraneanos inducidos por la maniobra de Valsalva y la tos.Resultados: durante la maniobra de Valsalva y la tos el cerebro fue propulsado en bloque hacia la craniectomía. Movimientos notorios se observaron a nivel centroencefálico y este fenómeno se atribuyó fundamentalmente al ascenso de LCR desde la columna y la distensión de las cisternas de la base. La magnitud de los cambios morfológicos fue proporcional al esfuerzo respiratorio y la presión intracraneana. Conclusiones: la maniobra de Valsalva y la tos provocaron cambios morfológicos bruscos e importantes a nivel centroencefálico, A la luz de teorías recientes se discuten las eventuales consecuencias de esta movilidad patológica sobre las estructuras témporomesiales y las funciones cognitivas. Estas observaciones constituyen un firme argumento en favor de la craneoplastia precoz.
