Peri-spinal Neurovascular Response Triggered by a Painless Electrical Nerve Stimulation in Patients with Chronic Arterial Hypertension

Purpose: Alterations of the central nervous system are frequent complications in patients with chronic arterial hypertension (AHT). However, functional spinal cord lesions are not often detected in these patients despite diagnostic advances in neuroimaging and electrophysiology. Recently, a new non-invasive functional near infrared spectroscopy (fNIRS) application was developed for assessment of the peri-spinal neurovascular response (NVR) as a functional test of the spinal cord. Methods: The continuous wave fNIRS technique was applied to detect changes in O₂Hb concentration during the peri-spinal NVR triggered by non-noxious electrical stimulation of the median nerve at the wrist, and recorded at cervical and thoracic spinal levels using three different stimulation protocols in subjects with AHT treated with losartan (n = 22; 142.14 ± 133.9 months of disease) and compared to healthy control subjects (n = 37). The body mass index (BMI) and the median nerve conduction velocity (NCV) were also recorded. Results: The NVR of patients with AHT showed a significantly lower amplitude (− 70.4%; cervical), longer rise time (+ 22.2%; cervical), and longer duration (+ 28.0%; thoracic) than the control group (p < 0.01). The stimulus intensity-response in the AHT group was − 53.5%, − 55.9%, and − 63% lower in amplitude than the controls (p < 0.05) for the increasing stimulus intensity steps (5; 7.5 and 10 mA, respectively) at the cervical level. Patients with BMI > 30 showed more intense changes. The median NCV was normal for both groups. Conclusion: These data show, for the first time, the difference in peri-spinal NVR between normal subjects and losartan-treated ATH patients, indicating the potential of a non-invasive fNIRS technique to find sensory functional abnormalities of the spinal cord in these patients.