Comparison of effects of Scalp Nerve Block versus Local Anaesthetic infiltration on inflammatory response in patients undergoing Craniotomy- A Randomized controlled trial

Craniotomies are often associated with significant perioperative stress response, leading to alterations in neuro-endocrine hormones and cytokines and hence linked to poor neurological outcomes, increased post-operative complications like mortality and longer intensive care unit and hospital stays. The immune response is influenced by the type of surgery as well as the anaesthetic technique.

 The immune responses can be measured by changes in differential counts, lymphocytes subsets, plasma concentrations of pro-inflammatory cytokines(Interleukin-2, IL-6, IL-12, Interferon-g) and anti-inflammatory cytokines(IL-10, transforming growth factor b) and plasma concentrations of cortisol, epinephrine and nor epinephrine measured before and after surgery.

Neutrophils-to-lymphocyte ratio (NLR) and Platelets-to-lymphocyte ratio (PLR) derived from routine complete blood count tests have emerged as a simple reliable biological marker and cost effective for evaluating systemic inflammation, stress response, and predicting outcome in various surgical populations.

In the context of craniotomy, alterations in NLR and PLR may also serve as surrogate markers for the degree of perioperative stress and inflammation as in various other clinical conditions such as sepsis, cardiovascular diseases and malignancies.

Regional anaesthesia has been speculated to decrease the inflammatory and immunosuppressive responses.Scalp nerve block(SNB) and local anaesthetic infiltration(LI) of the scalp have been proposed to blunt hemodynamic response to craniotomy, reduced anaesthetic requirements, decrease opioid consumption, and reduce postoperative pain perception during craniotomies. In addition, SNB has been shown to attenuate the neuroendocrine stress response by reducing sympathetic activation and inflammatory mediator release. This is probably due to blockade of C-fibres carrying pain and hence reduced activity of sympathetic nerve fibres.

Since there is limited evidence of studies comparing the impact of SNB and LI on post-operative inflammatory response, we intended to study their effect on NLR and PLR 24 & 48 hours post-operatively in patients undergoing craniotomies.