Cerebral autoregulation following minor head injury

Abstract

<jats:p>The purpose of this study was to determine whether patients with minor head injury experience impairments in cerebral autoregulation. Twenty-nine patients with minor head injuries defined by Glasgow Coma Scale (GCS) scores of 13 to 15 underwent testing of dynamic cerebral autoregulation within 48 hours of their injury using continuous transcranial Doppler velocity recordings and blood pressure recordings. Twenty-nine age-matched normal volunteers underwent autoregulation testing in the same manner to establish comparison values. The function of the autoregulatory response was assessed by the cerebral blood flow velocity response to induced rapid brief changes in arterial blood pressure and measured as the autoregulation index (ARI).</jats:p><jats:p>Eight (28%) of the 29 patients with minor head injury demonstrated poorly functioning or absent cerebral autoregulation versus none of the controls, and this difference was highly significant (p = 0.008). A significant correlation between lower blood pressure and worse autoregulation was found by regression analysis in head-injured patients (r = 0.6, p &lt; 0.001); however, lower blood pressure did not account for the autoregulatory impairment in all patients. Within this group of head-injured patients there was no correlation between ARI and initial GCS or 1-month Glasgow Outcome Scale scores. This study indicates that a significant number of patients with minor head injury may have impaired cerebral autoregulation and may be at increased risk for secondary ischemic neuronal damage.</jats:p>

Dynamic Autoregulatory Response After Aneurysmal Subarachnoid Hemorrhage and Its Relation to Angiographic Vasospasm and Clinical Outcome

“…Following exclusion of ARI-values calculated with a RRdecrease B20 mmHg or random values caused by motion artifacts, correlation analysis of median ARI-values has been done with quantitative pVS-, graded pVS-, and graded gVS-values. ARI-scores around five are considered as physiological [21,22].…”

Neural network modelling of dynamic cerebral autoregulation: assessment and comparison with established methods

“…Previous studies of dynamic cerebral autoregulation that used thigh cuff manoeuvres to induce a sudden change in mean ABP addressed the variability of the autoregulation index (ARI), obtained from Aaslid's model [18,19], and its distribution in pathological conditions such as stroke [10], carotid artery disease [27], and severe head injury [28]. To our knowledge, this is one of the first investigations into the predictive power of Aaslid's model and other system identification methods, using multiple thigh cuff manoeuvres to create separate training and validation sets of data.…”

The Pathophysiology of Concussion

“…When this mechanism is disturbed, symptoms may occur in response to changes in cerebral blood flow (CBF) such as migraine headaches. Acutely after mild TBI, there is a decrease in cerebral autoregulation capacity [34]. A diffuse reduction of cerebral blood flow occurs immediately after moderate LFP injury, with focal recovery occurring more slowly at the site of injury [35].…”