ADVANCES IN SPORT CONCUSSION ASSESSMENT may not be at its highest when external pressure or a strong desire to return to play is present (McCrea et al., 2004). Furthermore, some athletes report symptoms at rest, justifying the importance of obtaining preseason baseline symptom scores (Lovell et al., 2006; Mailer et al., 2008). Overall, it appears that symptom recovery following concussion diagnosis has been used as a guide for injury recovery, but it is not a definitive return-to-play tool. This protocol is evidenced by the variant recovery patterns noted between symptoms and cognitive function (Broglio et al., 2007b; Fazio et al., 2007). In light of this evidence, symptom evaluation may not reflect the resolution of all post-concussion decrements, and therefore should only be used in combination with other evaluative measures and not as a sole indicator for return to play. The practicality of symptom reports as an indicator of concussion is clear, but further investigative work is needed. What is most needed is a better understanding of how to obtain accurate concussion symptom reports from injured athletes. In addition, revision of the symptom list may be in order. Piland and colleagues (Piland et al., 2003, 2006) noted that nine symptoms may best characterize concussion by removing confounding symptoms, but this scale has not been widely adopted. In addition, clinical guidelines for return to play note that no athlete should return to sport participation while still symptomatic (Guskiewicz et al., 2004b; Kissick and Johnston, 2005). However, recent evidence has shown a clinical improvement in those who participated in moderate activity while still symptomatic (Majerske et al., 2008; Willer and Leddy, 2006). A better understanding of how exercise may increase or decrease recovery from concussive injuries is clearly warranted. Postural Stability Balance plays a vital role in the maintenance of fluid dynamic movement common in sport. Balance is the process of maintaining the center of gravity within the body’s base of support, and many factors enter into the task of controlling balance within this designated area ( Jacobs and Horak, 2007). The system involves a complex network of neural connections and centers that are related by peripheral and central feedback mechanisms. A hierarchy integrating the cerebral cortex, cerebellum, basal ganglia, brainstem, and spinal cord is primarily responsible for controlling voluntary movements (Guyton, 1986; Vander et al., 1990). Postural instability has been identified in pathological conditions such as moderate to severe TBI (Geurts et al., 1996; Ingersoll and Armstrong, 1992; Mallinson and Longridge, 1998; Wober et al., 1993), hemiplegia and craniocerebral injury (Arcan et al., 1977), cerebellar atrophy and ataxia (Mauritz et al., 1979), and whiplash (Mallinson and Longridge, 1998; Rubin et al., 1995). It has been proposed that communication between sensory systems is lost in the majority of these individuals, causing moderate to severe postural instability in either the anterior-posterior direction, medial-lateral direction, or both. In most cases, symptoms such as dizziness, vertigo, tinnitus, lightheadedness, blurred vision, and photophobia, all having visual, vestibular, and=or somatosensory orientation, are reported (Geurts et al., 1996; Ingersoll and Armstrong, 1992; Mallinson and Longridge, 1998; Rubin et al., 1995; Wober et al., 1993).
2367 More recently, balance and postural stability have been studied as objective measures in the evaluation of athletes with acute cerebral concussion. Concussed athletes have demonstrated balance deficits following concussion using both high-tech and clinical methods of assessment. In most cases, decreases in postural stability persisted for up to 3 days following injury in comparison to control subjects, and were most evident when the subjects were standing either on a foam or moving (tilting) surface. Subsequent studies have identified decreases in postural stability for up to 3 days postinjury using the Sensory Organization Test (SOT) on the NeuroCom Smart Balance Master (Guskiewicz et al., 1997, 2001). Using the SOT, Guskiewicz and associates (2001) also found that overall balance performance typically recovers between days 1 and 3 post-injury. These studies identified deficits between concussed and control subjects, especially when visual and support surface conditions were altered. Athletes appear to have sensory interaction and decreased postural control until approximately 3 days following injury. The athletes gradually recover to approximately the scores of matched control subjects by day 10 post-injury. It appears that this deficit is related to a sensory interaction problem, whereby the concussed athlete fails to use their visual and vestibular systems effectively. The integration of visual and vestibular information is essential for the maintenance of equilibrium under certain altered conditions similar to those performed during the SOT (Nashner and Berthoz, 1978; Nashner, 1976; Nashner et al., 1982). If an athlete has difficulty balancing under conditions in which sensory systems have been altered, it can be hypothesized that they are unable to ignore altered environmental conditions and therefore select a motor response based on the altered environmental cues. The SOT requires sophisticated force plate systems that provide a way to challenge and alter information sent to the various sensory systems. While the aforementioned studies suggest that force platform sway measures provide valuable information in making return-to-play decisions following concussion, there is still a question of practicality and accessibility for the sports medicine clinician. In an attempt to provide a more cost-effective, yet quantifiable method of assessing balance in athletes, the Balance Error Scoring System (BESS) was developed by researchers at the University of North Carolina. This clinical balance test can be administered on the sideline (Guskiewicz, 2001). In the absence of sophisticated force plate technology, the use of a quantifiable clinical test battery such as the BESS is recommended. Three different stances (double, single, and tandem) are completed twice, once while on a firm surface and once while on piece of medium-density foam (Airex Balance Pad 81000; www.power-systems.com) for a total of six trials (Fig. 1). Athletes are asked to assume the required stance by placing their hands on the iliac crests, and that upon eye closure the 20-sec test begins. During the single leg stances, subjects are asked to maintain the contralateral limb in 20–308 of hip flexion and 40–508 of knee flexion. The singlelimb stance tests are performed on the non-dominant foot. This same foot is placed towards the rear on the tandem stances. Subjects are told that upon losing their balance, they are to make any necessary adjustments and return to the starting position as quickly as possible. Performance is scored by adding one error point for each error committed (Table 1).