[Relationship between cerebral circulatory arrest and loss of brain functions--analysis of patients in a state of impending brain death].

To clarify the temporal discrepancies between cerebral circulatory arrest and loss of brain functions in relation to neuroradiological differences of brain damage, we analyzed 100 cases of impending brain death evaluated by neurological findings and continuous, simultaneous neuromonitoring of somatosensory and brainstem auditory evoked potentials (SEP, BAEP), compressed spectral arrays (CSA), and transcranial Doppler sonography (TCD). A) Cases of supratentorial lesions: 1) Loss of brain functions after supratentorial circulatory arrest (TCD) were advanced rostrocaudally -(SEP N20 > CSA) > (BAEP III-V > SEP P13/14). 2) All patients demonstrated supratentorial circulatory arrest (TCD) after both neurological and cerebral (CSA) functions had been lost for more than 6 hours or after loss of neurological, cerebral (CSA), and brainstem (BAEP, SEP) functions. B) Cases of diffuse or infratentorial lesions: Supratentorial circulation persisted in a few cases after loss of all brain functions. C) The interval from supratentorial circulatory arrest to brainstem function loss was longer than that to cerebral function loss. Both intervals were less than 24 hours in almost all cases. In applying ancillary studies to the diagnosis of brain death, consideration should be given to the time lag between cerebral circulatory arrest and loss of brain functions caused by pathophysiological differences in brain damage.