Chiropractic Intervention and Oculomotor Function in Young Adults with Persistent Mild Traumatic Brain Injury Symptoms

Participants will first be assessed for inclusion criteria, if appropriate for this study they will undergo a baseline assessment, then be randomly allocated to either the intervention or control group and the appropriate intervention applied. The chiropractic intervention consists of a single session of chiropractic care. The control intervention will consist of a series of movements, detailed below, designed to account for vestibular and proprioceptive input that may occur in the course of a chiropractic session. Chiropractic intervention will be provided by a volunteer chiropractor from Auckland. The attending chiropractor will be recruited or volunteer to provide care. Chiropractors will be asked to treat study participants like any other patient presenting to their practice. Chiropractors will not be limited to any particular type or technique of care, so chiropractors will be able to tailor the care they provided to the participant’s individual clinical needs. This will enable chiropractors to modify the type and frequency of care throughout the trial, which reflects normal chiropractic clinical practice. This means that the nature of chiropractic care provided may vary between participants within the intervention group. Following the participant’s final assessment, their treating chiropractor will be asked for a description and frequency of care so a summary of interventions used in the trial can be presented. Chiropractic care in this trial will involve the on-going provision of care, whether a subjective complaint is present or not, with the intention of correcting spinal dysfunction, which is termed vertebral subluxation by chiropractors (Haavik Taylor, Holt et al. 2010, Henderson 2012). Clinical indicators of vertebral subluxation, such as palpable restricted intersegmental range of motion and tenderness to palpation of the joint, can be used to guide the chiropractic clinical decision making process, as opposed to areas of pain or symptoms (Owens 2002, Cooperstein, Haneline et al. 2010, Henderson 2012). When applied in this fashion, the goal of chiropractic care is to enhance health as opposed to treating a specific subjective complaint (de Souza and Ebrall 2008). In this trial, all patients will be examined and treated using procedures that are customarily used in chiropractic practice, and that conform to best practice guidelines and the scope of chiropractic practice specified by the New Zealand Chiropractic Board (New Zealand Chiropractic Board 2007). In general, chiropractic visits last from ten to thirty minutes and involve the chiropractor taking a subjective report, before assessing the participant, and providing chiropractic care based on the findings present and care plan recommendations. Chiropractors will be asked to inform the principal investigator if any serious adverse events occurred while the participant was under their care. Chiropractic procedures that are commonly used predominantly consist of: 1. High velocity, low amplitude spinal and extremity adjustments with direct manual contact, typically resulting in joint cavitation (Evans 2002) 2. Table assisted chiropractic adjustments that involve direct manual contact of the spine and a segmental drop table to enhance the motion force imparted towards the segment or area to be adjusted (Homack 2005). 3. Very high velocity, low amplitude adjustments using a mechanical instrument for force delivery (Fuhr, Colloca et al. 1997, Nadler, Holder et al. 1998). These procedures fall into a number of named proprietary technique packages that can be used on their own or in an eclectic approach. These named technique packages include Diversified Technique, Gonstead Chiropractic Technique, Activator Methods Chiropractic Technique, Thompson Technique, and Torque Release Technique (Cooperstein and Gleberzon 2004). Chiropractors will also be able to include rehabilitative exercises, stretching, and other non-adjustive treatments that are routinely used in chiropractic practice (Coulter and Shekelle 2005, Holt, Kelly et al. 2009). The researchers choose to leave the decisions regarding the approach to care up to the individual chiropractors, as in the past, chiropractic researchers have been criticised for designing interventions in randomised controlled trials that do not reflect usual chiropractic practice (Hawk, Khorsan et al. 2007). It is thought that this prescriptive approach to trial interventions limits the generalisability of results from chiropractic trials when considered from a whole systems research point of view (Hawk, Khorsan et al. 2007, Rosner 2012). The control intervention will include passive and active movements of the participants head, spine, and body. It will include moving the participant into spinal adjustment setup positions but without delivering an adjustment thrust or loading tension into any spinal joints. Pre-loading a joint, as is normal prior to spinal adjusting has been shown to alter paraspinal proprioceptive firing in anesthetised cats (Pickar & Wheeler, 2001). This intervention will control for possible physiological changes occurring due to the cutaneous, muscular, or vestibular input that would occur with the type of passive and active movements involved in assessing the participants prior to an adjustment and setting up for an adjustment. An active control involving passive and active movements has been chosen to determine if the difference in outcome measures is due to the application of a high-velocity low-amplitude thrust or other cutaneous, muscular, or vestibular input caused by passive and active movements during a chiropractic session.