Although acupuncture therapy has demonstrated itself to be effective in several clinical areas, the underlying mechanisms of acupuncture in general and the analgesic effect in particular are, however, still not clearly delineated. We, therefore, have studied acupuncture analgesic effect through fMRI and proposed a hypothesis, based on the obtained result, which will enlighten the central role of the brain in acupuncture therapy. The proposed model, termed as a broad sense hypothalamus-pituitary-adrenal (BS-HPA) axis, was based on our observed neuroimaging results. The model incorporates the stress-induced HPA axis model together with neuro-immune interaction including the cholinergic anti-inflammatory model. The obtained results coupled with accumulating evidence suggest that the central nervous system is essential for the processing of these effects via its modulation of the autonomic nervous system, neuroimmune system and hormonal regulation. Based on our fMRI study, it appears that understanding the effects of acupuncture within a neuroscience-based framework is vital. Further, we have proposed the broad sense-HPA axis hypothesis which incorporates the experimental results.

Purpose: The purpose of this study was to assess the extent of the increased intracranial pressure (ICP) resulting from CO₂ pneumoperitoneum and steep Trendelenburg positioning using ultrasonographic measurement of optic nerve sheath diameter (ONSD) in patients undergoing robot-assisted laparoscopic radical prostatectomy (RALRP). Patients and Methods: Twenty patients who underwent elective RALRP were enrolled in this study. ONSD and regional cerebral oxygen saturation (rSO₂) were investigated noninvasively using ocular ultrasonography and near-infrared spectroscopy before anesthesia (T0), 10 minutes after anesthesia induction in the supine position (T1), 10 and 30 minutes after CO₂ pneumoperitoneum with 30-degree Trendelenburg positioning (T2 and T3), and after returning to supine position without CO₂ pneumoperitoneum at the conclusion of the RALRP (T4). Results: The mean values of ONSD at all time points (T1, T2, T3, and T4) after general anesthesia significantly increased compared with that before general anesthesia (T0). During CO₂ pneumoperitoneum with 30-degree Trendelenburg positioning (T2, T3), a significant increase of 12.5% in ONSD was observed in comparison with ONSD after anesthesia induction in the supine position without CO₂ pneumoperitoneum (T1). Three patients had an ONSD value equivalent to an ICP above 20 mm Hg, and these patients did not experience a decrease of rSO₂ or any neurologic complications. Conclusions: In patients undergoing RALRP, the increase of 12.5% in ONSD during CO₂ pneumoperitoneum with steep Trendelenburg positioning was observed and thus the increase of ICP corresponding to this change of ONSD could be predicted. In 15% of the enrolled patients, ONSD increased by values equivalent to an ICP above 20 mm Hg without a deterioration of rSO₂ or any neurologic complications.

Yoo YC, et al. Yonsei Med J. 2012 Nov;53(6):1197-1202. http://dx.doi.org/10.3349/ymj.2012.53.6.1197

Kim NY, et al. Yonsei Med J. 2015 May;56(3):737-743. http://dx.doi.org/10.3349/ymj.2015.56.3.737

This study aimed to determine whether continuous deep neuromuscular blockade (NMB) improves the surgical conditions and facilitates robotic-assisted laparoscopic radical prostatectomy (RALRP) under low intra-abdominal pressure (IAP) to attenuate the increase in intraocular pressure (IOP) during CO₂ pneumoperitoneum in the steep Trendelenburg (ST) position. Sixty-seven patients undergoing RALRP were randomly assigned to a moderate NMB group (Group M), including patients who received atracurium infusion until the end of the ST position, maintaining a train of four count of 1–2; and the deep NMB group (Group D), including patients who received rocuronium infusion, maintaining a post-tetanic count of 1–2. IOP was measured in all patients at nine separate time points. All RALRPs were performed by one surgeon, who rated the overall and worst surgical conditions at the end of the ST position. The highest IOP value was observed at T4 (60 min after the ST position) in both Group M (23.3 ± 2.7 mmHg) and Group D (19.8 ± 2.1 mmHg). RALRP was accomplished at an IAP of 8 mmHg in 88% Group D patients and 25% Group M patients. The overall surgical condition grade was 4.0 (3.0–5.0) in Group D and 3.0 (2.0–5.0) in Group M (P < 0.001). The current study demonstrated that continuous deep NMB may improve surgical conditions and facilitate RALRP at a low IAP, resulting in significant attenuation of the increase on IOP. Moreover, low-pressure pneumoperitoneum, facilitated by deep NMB still provided acceptable surgical conditions. ClinicalTrials.gov NCT02109133