Neuromodulation of cerebral blood flow

This thesis is focused on the modulation of cerebral blood flow (CBF) by cervical electrical stimulation and the assumption that the sympathetic nervous system plays a specific role as a pathway. We were aware of some results with cervical spinal cord stimulation (SCS), but chose to focus on transcutaneous electrical neurostimulation (TENS) because of its non-invasive nature. Anatomical aspects of innervation of cerebral vessels are described and the role of sympathetic nervous system in CBF regulation in humans is demonstrated. A laboratory environment was created to perform physiological measurements while using TENS or SCS and statistical methods were applied for ad-hoc analysis. These measurements and methods were finally applied in three separate studies on small groups of subjects. These studies have provided knowledge on how to study the effects of electrical stimulation on CBF, on the clinical effects of electrical stimulation (regarding CBF) and on the feasibility of electrical stimulation in patients.
In conclusion TENS was shown to be safely applicable, but unfeasible to treat restless patients. When using TENS we found some small increases in CBF, but only when CBF is already challenged. In the experiments with SCS we found effects on the sympathetic system as well. Taking into account other known studies on the subject we postulate a role for a “trigemino-sympathetic” reflex arch. Before one can draw conclusions about the clinical applicability of neuromodulation in order to improve CBF, more research is needed on more invasive procedures. Suggestions are provided.