OBJECTIVE: Dissociation is a mental process with psychological and somatoform manifestations, which is closely related to hypnotic suggestibility and essentially shows the ability to obtain distance from reality. An increased tendency to dissociate is a frequently reported characteristic of patients with functional neurological symptoms and syndromes (FNSS), which account for a substantial part of all neurological admissions. This review aims to investigate what heart rate variability (HRV), EEG and neuroimaging data (MRI) reveal about the nature of dissociation and related conditions.

METHODS: Studies reporting HRV, EEG and neuroimaging data related to hypnosis, dissociation and FNSS were identified by searching the electronic databases Pubmed and ScienceDirect.

RESULTS: The majority of the identified studies concerned the physiological characteristics of hypnosis; relatively few investigations on dissociation related FNSS were identified. General findings were increased parasympathetic functioning during hypnosis (as measured by HRV), and lower HRV in patients with FNSS. The large variety of EEG and functional MRI investigations with diverse results challenges definite conclusions, but evidence suggests that subcortical as well as (pre)frontal regions serve emotion regulation in dissociative conditions. Functional connectivity analyses suggest the presence of altered brain networks in patients with FNSS, in which limbic areas have an increased influence on motor preparatory regions.

CONCLUSIONS: HRV, EEG and (functional) MRI are sensitive methods to detect physiological changes related to dissociation and dissociative disorders such as FNSS, and can possibly provide more information about their aetiology. The use of such measures could eventually provide biomarkers for earlier identification of patients at risk and appropriate treatment of dissociative conditions.

J Neurol Neurosurg Psychiatry. 2012 Nov 22. van der Kruijs SJ, Bodde NM, Carrette E, Lazeron RH, Vonck KE, Boon PA, Langereis GR, Cluitmans PJ, Feijs LM, Hofman PA, Backes WH, Jansen JF, Aldenkamp AP. Epilepsy Centre Kempenhaeghe, , Heeze, The Netherlands.

Abstract Objectives: The aim of this study was to investigate the effect of ear-press needle acupuncture on Yintang point for preoperative anxiety. Design: This was a prospective, randomized, single-blind, controlled study. Settings/location: The study setting was the Department of Anesthesiology in Ankara Training and Research Hospital of Ministry of Health, Ankara, Turkey. Subjects: The study comprised 52 adult surgical patients. Interventions: A single, 20-minute session of single-point acupuncture was applied on Yintang (acupuncture group) or sham point (sham acupuncture group). Outcome measures: The efficacy of acupuncture was evaluated by means of the changes in bispectral index (BIS) and STAI (State-Trait Anxiety Index). Results: BIS values in the acupuncture group were significantly lower than in the sham group in all time intervals (p<0.0042). BIS values were lower than baseline in the study group during the entire study period (p<0.0004) while no such effect has been observed in the sham group (p>0.0004). Mean values of state anxiety (STAI-S) decreased after acupuncture in the study group (p=0,018), while no change was observed in trait anxiety (STAI-T) (p=0.156). Patients of the sham group showed no change in both parameters (p=0.387 and p=0,116). Conclusions: Ear-press needle acupuncture on Yintang point reduces preoperative anxiety in adult surgical patients.

J Altern Complement Med. 2012 Dec 27. Acar HV, Cuvas O, Ceyhan A, Dikmen B. Department of Anesthesiology and Intensive Care, Ankara Training and Research Hospital of Ministry of Health , Ankara, Turkey .