Cerebral Autoregulation and Neurovascular Coupling after Craniospinal Irradiation in Long-Term Survivors of Malignant Pediatric Brain Tumors of the Posterior Fossa

Abstract

Introduction Long-term survivors of craniospinal irradiation have an increased risk for stroke which increases with radiation dose and follow-up time. Radiotherapy induces structural changes of the cerebral vasculature, affecting both, large, and small vessels. It is unknown how these structural changes affect functional mechanisms of cerebral blood flow regulation such as cerebral autoregulation and neurovascular coupling. Methods Using the transcranial Doppler, we compared dynamic cerebral autoregulation and neurovascular coupling of 12 patients after long-term survival of craniospinal irradiation due to a malignant pediatric brain tumor of the posterior fossa and 12 age- and sex-matched healthy patients. Mean arterial blood pressure and cerebral blood flow velocities in the middle and posterior cerebral artery were recorded at rest during normal breathing to assess cerebral autoregulation (transfer function parameters phase and gain, as well as the correlation coefficient indices Mx, Sx, and Dx), and during 10 cycles of a visual task to assess neurovascular coupling (parameters time delay, natural frequency, gain, attenuation, and rate time). Results Parameters of cerebral autoregulation showed a consistent trend toward reduced cerebral autoregulation in patients that did not reach statistical significance. Neurovascular coupling was not altered after craniospinal irradiation. Conclusion In this pilot study, we demonstrated a trend toward reduced cerebral autoregulation, and no alteration of neurovascular coupling after irradiation in long-term survivors of malignant pediatric brain tumors of the posterior fossa.

Reliability and validity of the mean flow index (Mx) for assessing cerebral autoregulation in humans: A systematic review of the methodology

“…33 Higher values of Mx in different patient populations compared to healthy control groups were also obtained in patients with alcohol withdrawal syndrome (patients, n = 20, 0.16, SE: 0.05; controls, n = 20, 0.00 SE 0.04), 34 obstructive sleep apnoea (patients, n = 11, 0.41 ± 0.13; controls, n = 9, 0.23 ± 0.10), 35 schizophrenia (patients, n = 21, 0.40; controls, n = 23, 0.26), 36 and intracerebral haemorrhage (patients, n = 12, 0.41 ± 0.27; controls, n = 7, 0.17 ± 0.13), 37 whereas patients admitted to a neurorehabilitation unit showed lower values of nMxa compared to healthy controls (patients, n = 14, 0.04, SE: 0.07; healthy, n = 15, 0.35, SE: 0.07; p < 0.01). 38 In contrast, no differences were found in patients with migraine compared with healthy volunteers 39,40 (19 patients vs. 75 healthy volunteers: mean nMxa 0.29 ± 0.17 vs. 0.27 ± 0.17 39 ; 22 patients vs. 22 healthy volunteers: mean nMxa 0.24 vs. 0.26) 40 ) patients with a brain tumour vs. healthy volunteers (12 patients vs. 12 healthy volunteers: mean nMxa 0.45 ± 0.10 vs. 0.36 ± 0.18 41 ) and critically ill patients with compared to without sepsis (52 septic vs. 40 non-septic: Mean nMxa 0.33 (IQR: 0.08–0.58) vs. 0.31 (IQR: 0.04–0.59) 23 )…”