Health & body · 2022
What changes in brain blood-flow regulation accompany after a ?
In this retrospective study, delayed cerebral ischemia was associated with loss of cerebral autoregulation and vasoparalysis. Among the 19 patients who developed it, vasospasm was accompanied by a rise in the autoregulation index Mxa and a fall in critical closing pressure measured by the Aaslid method on the side of the spasm.
Details
In patients with subarachnoid hemorrhage (SAH), delayed cerebral ischemia (DCI) is partly associated with vasospasm (VS) and impaired cerebral autoregulation—the regulation of brain blood flow. The researchers investigated changes in transcranial Doppler (TCD)–derived indices of cerebrovascular dynamics during vasospasm, comparing patients according to whether they developed DCI.
This was a retrospective analysis of recordings from 32 SAH patients whose vasospasm was diagnosed through bilateral TCD measurements. Patients were divided into two groups according to whether DCI developed.
Cerebral autoregulation was estimated using the moving correlation coefficient Mxa, calculated from spontaneous fluctuations in cerebral blood flow velocity (CBFV) and arterial blood pressure (ABP). The researchers also measured the cerebral arterial time constant (tau), defined as resistance (Ra) multiplied by compliance (Ca), and critical closing pressure (CrCP), assessed using two methods: CrCPAaslid and CrCPVarsos.
Across all 32 patients, tau on the side of the spasm was shorter during vasospasm than before it: 0.17 ± 0.08 versus 0.25 ± 0.17 sec (p = 0.04). CrCPAaslid on that side was also lower during vasospasm than before it: 9.69 ± 23.28 versus 27.23 ± 23.31 mmHg (p = 0.01). There was an asymmetry between the brain hemispheres, with lower CrCPAaslid on the side of the spasm (p < 0.01).
During vasospasm, CrCPAaslid on the side of the spasm was negatively correlated with Mxa (r = -0.43, p = 0.01), whereas CrCPVarsos was positively correlated with tau (r = 0.74, p < 0.001).
Among the patients who developed DCI (N = 19), Mxa on the side of the spasm was higher during vasospasm than before it: 0.36 ± 0.18 versus 0.26 ± 0.23 (p = 0.04). CrCPAaslid on that side was lower during vasospasm than before it: 6.61 ± 24.5 versus 17.24 ± 19.4 mmHg (p = 0.04). CrCPAaslid was also lower on the side of the spasm than on the opposite side (p < 0.01).
The authors concluded that tau and CrCP were reduced during vasospasm in both temporal and spatial assessments, while DCI was associated with loss of autoregulation and vasoparalysis.
What do you think?
Good conversations begin with curiosity.
You can read comments without an account. Sign in to write.
Loading comments…