Case Study. Assessment of Mild Head Injury Using Measures of Balance and Cognition: A Case Study

Transcription

1 Journal of Sport Rehabilitation, 1997,6, Human Kinetics Publishers, Inc. Case Study Assessment of Mild Head Injury Using Measures of Balance and Cognition: A Case Study Bryan L. Riemann and Kevin M. Guskiewicz Mild head injury (MHI) represents one of the most challenging neurological pathologies occurring during athletic participation. Athletic trainers and sports medicine personnel are often faced with decisions about the severity of head injury and the timing of an athlete's return to play following MHI. Returning an athlete to competition following MHI too early can be a catastrophic mistake. This case study involves a 20-year-old collegiate football player who sustained three mild head injuries during one season. The case study demonstrates how objective measures of balance and cognition can be used when making decisions about returning an athlete to play following MHI. These measures can be used to supplement the subjective guidelines proposed by many physicians. Objective assessment following mild head injury (MHI) can be made through the use of cognitive and postural measures. Both of these objective measures have been reported to be valid in the assessment of head injury (1-3,6,9, 11-13). In this case study, the Sensory Organization Test (SOT) on the NeuroCom EquiTest System (Figure 1) was used to assess balance and the Trail Making Test was used to assess cognitive function in a collegiate football player who sustained three concussions during the 1995 season. The postural control system uses three sensory systems to operate a feedback control circuit between the brain and the musculoskeletal system. Under normal circumstances, a person balances with the aid of information from the visual, vestibular, and somatosensory systems. If one system is deficient, the other systems should compensate for the deficiency. The SOT is designed to systematically disrupt the sensory selection process by altering the orientation information available to the somatosensory andlor visual inputs while measuring the subject's ability to maintain equilibrium. The test protocol consists of three 20-s trials under Bryan L. Riemann is a graduate student in Sports Medicine, University of North Carolina, Chapel Hill, NC. Kevin M. Guskiewicz is with the Department of Physical Education, Exercise and Sport Science, University of North Carolina, Chapel Hill, NC

2 284 Riemann and Guskiewicz Figure 1 - NeuroCom EquiTest System used for assessment of postural stability. three different visual conditions (eyes open, eyes closed, sway referenced) and two different surface conditions (fixed, sway referenced). Sway referencing involves tilting the support surface and/or visual surround to directly follow the athlete's center of gravity (COG) sway such that the orientation of the surface remains constant in relation to the COG angle. With this technique, the somatosensory system, the visual system, or both report that the subject's orientation to gravity is constant when in fact it is changing, requiring the subject to ignore the inaccurate information from the sway-referenced sense(s). An overall composite equilibrium score describing a person's overall level of performance during all the trials in the SOT is calculated, with higher scores indicating better balance performance. The average composite equilibrium score calculated from 225 healthy collegiate athletes at preseason was 76 (10). Additionally, relative differences between the equilibrium scores of various conditions are calculated using

3 Assessing Head lnjuly 285 ratios to reveal specific information about each sensory modality involved with maintaining balance. For example, a vestibular ratio is computed by using scores attained in Condition 5 (eyes closed, sway-referenced platform) and Condition 1 (eyes open, fixed platform). This ratio indicates the relative reduction in postural stability when visual and somatosensory inputs are simultaneously disrupted. Normal ratio scores based on 225 healthy athletes were as follows: somatosensory (.98), visual (.91), and vestibular (.70) (10). Altered cognitive functioning following MHI can also be ascertained through neuropsychological tests. The athlete in this case study was assessed using the Trail Making Test (Reitan Neuropsychology Laboratory, Tucson, AZ). The test allows for the assessment of orientation, concentration, visuospatial capacity, and problem solving abilities and has proven sensitive to deficits associated with mild head injury (1, 2). This test requires the athlete to sequentially trace a list of 25 numbers on a piece of paper as fast as possible using a pencil. The test is scored by recording the time taken to complete the task and adding 1 s for each sequential error committed. Scores taken on 225 healthy athletes at preseason averaged s (10). Case Study A 20-year-old Division I collegiate athlete sustained three head injuries during the 1995 football season. All injuries occurred during games while he was playing defensive back. Symptoms did not include loss of consciousness or amnesia for any of the injuries. The mechanism of injury for the player's first head injury involved a direct blow to the top of the head. Subjective symptoms reported by the athlete following the injury included headache, lasting 3 days; disequilibrium, lasting 2 days; and neck pain, lasting 1 day. Objective postural and cognitive assessments were initially made 2 days postinjury. Scores for both the Trail Making Test and SOT were below normal (Figures 2 and 3). Follow-up testing 3 days postinjury revealed improved scores on the Trail Making Test, as scores returned to normal levels. Improvement was also demonstrated on the SOT; however, scores still remained below normal. Assessment at 13 days postinjury revealed that deficits on the SOT had resolved and Trail Making Test scores continued to improve. The athlete returned to participation at this point. One month later, the athlete sustained a second MHI following a blind side hit to the left side of the head. The athlete immediately reported to the sports medicine staff complaining of mild dizziness and headache. In addition, neck pain and disequilibrium persisted for 2 days. Postural and cognitive testing were conducted 3 days postinjury. Results of the test demonstrated lower scores than those achieved at the previous testing session conducted 2 days after the first MHI. Scores, however, were above normal values, suggesting that the second injury was negligible. The athlete returned to participation 4 days after symptoms resolved. The third MHI occurred 1 month after the second MHI, when the athlete was struck in the head posteriorly by another player. The athlete did not report the

4 286 Riemann and Guskiewicz injury until 1 day postinjury and therefore finished the game in which he sustained the injury. Headaches and disequilibrium persisted for 2 days following the injury. The postural and cognitive tests were administered at 1 day, 2 days, and 3 days postinjury. Results for the Trail Making Test were abnormal at 1 day postinjury but normal for subsequent tests (Figure 2). The SOT administered on each of the 3 days revealed below-normal scores. The scores were lower than those recorded following the first injury (Figure 3). As a result of sustaining a third episode of mild head injury, the athlete's season was terminated. The Trail Making Test and SOT were again administered approximately 3 months after the conclusion of the 1995 season. Scores had improved from the preceding assessment after the third MHI; however, the SOT values still remained below normal.! -t MHI Subject 0 M W Dl 3 Dl M t13 Postseason First MHI Third MHI Figure 2 - Trail Making scores for the MHI athlete. : -t MHI Subject 0 D2 D3 Dl3 Dl D2 D3 Postseason First MHI Third MHI Figure 3 - SOT composite scores for the MHI athlete.

5 Assessing Head Injury 287 Discussion The balance and cognitive deficits demonstrated by this athlete following MHI are not uncommon. The benefit of taking such measures is that improvement or progress can be measured daily or weekly. This becomes especially important when managing an athlete who has sustained multiple head injuries. The cumulative effects of multiple MHI, leading to progressive cognitive and neurological dysfunctions, represent an area void of scientific investigation. Athletes who have sustained two or three subsequent MHI have been shown to exhibit slower cognitive recoveries (8); however, the recovery curves for the Trail Making Test in this case study did not illustrate this phenomenon. The recovery curves for balance testing, however, across the first and third injuries demonstrated slower recovery times following subsequent injury. The composite scores following the first MHI returned to normal levels by Day 4 postinjury, whereas they remained depressed at Day 4 following the third MHI. Additionally, the composite score was found to remain below normal ranges at 3 months postseason. Analysis of the balance system components illustrated slower recovery patterns in both the vestibular and visual systems (Figure 4). Analysis of the sensory components of balance after subsequent testing in this case study revealed sensory interaction problems following each MHI. While the somatosensory and visual ratios remained relatively constant across testing days, the vestibular system lagged behind initially and gradually improved over time. These results suggest there may have been a sensory integration problem during the first few days following MHI. The three systems normally work in a compensatory manner, whereby if one system is not available to aid in controlling balance, the others compensate for the deficit. Effects of head injury directly on the vestibular system have been previously reported in the literature (14, 15). Balance and postural stability are crucial components for controlling movement strat- 0 -Vest -+-Visual -+- Sornato M D3 Dl 3 Dl M W Fostseason First MHI Third MHI Figure 4 - Sensory analysis for the MHI athlete illustrates impairment of the visual and vestibular systems following the first and third injuries.

6 288 Riemann and Guskiewicz egies involved in sport. Therefore, an athlete participating while experiencing disequilibrium from sensory interaction problems may be predisposed to further injury, especially in contact sports. It has been suggested that a single MHI increases an athlete's susceptibility to subsequent incidences by a factor of four compared to athletes who have never sustained a concussion (7). In contrast, others have suggested that the etiology of multiple MHI may be related to improper use of the head during athletic participation, a theory not supported by this case study, since three different mechanisms produced each of the injuries. The timing of an athlete's return to play following injury should be based on both subjective and objective evaluations. This decision is critical in the case of MHI, when the incidence of second impact syndrome is considered (4). Second impact syndrome involves fatal brain swelling following minor head trauma in individuals who still have symptoms from a prior head injury. It is thought that autoregulation of the brain is lost, resulting in catastrophic cerebral edema. Rest from collision and combative activities is the only rehabilitation approach currently available to treat MHI. The length of time an athlete is excluded from unrestricted activity has traditionally been based on subjective guidelines, such as those published by Cantu (5). The concern over these guidelines is their sole reliance on postconcussive symptoms as criteria for return to play. Summary Clinicians attempting to use measures of balance and cognition in MHI assess-. ment should strive to test at consistent intervals. Testing in this way will allow for more standardized comparisons to both preseason measures and normative data. Unfortunately, the athlete in this case study was undergoing additional diagnostic testing that prevented us from testing him at more consistent intervals. References 1. Alves, W.M., R.W. Rimel, and W.E. Nelson. University of Virginia prospective study of football-induced minor head injury: Status report. Clin. Sports Med. 6: , Barth, J., W. Alves, T. Ryan, S. Macciocchi, R. Rimel, J. Jane, and W. Nelson. Mild head injury in sports: Neuropsychological sequelae and recovery of function. In Mild Head Injury, H. Levin, H. Eisenberg, and A. Benton (Eds.). New York: Oxford Press, 1989, pp Barth, J., S. Macciocchi, B. Giordani, R. Rimel, J. Jane, and T. Boll. Neuropsychological sequelae of minor head injury. Neuros~~rgery 13: , Cantu, R.C. Minor head injuries in sports. In Proceedings of the Mild Brain Injury in Sports Summit, NATA Research and Education Foundation. Dallas, TX: National Athletic Trainers' Association, 1994, pp

7 Assessing Head lnjuty Cantu, R.C. Cerebral concussion in sports: Management and prevention. Sports Med. 14:64-74, Gentilini, M., P. Nichelli, and R. Schoenhuber. Neuropsychological evaluation of mild head injury. J. Neurol. Neurosurg. Psychiatry 48: , Gerberich, S., J. Priest, J. Boen, C. Staub, and R. Maxwell. Concussion incidence and severity in secondary school varsity football players. Am. J. Public Health 72: , Gromwall, D., and P. Wrightson. Cumulative effect of concussion. Lancet November 22: , Guskiewicz, K., and D. Perrin. Effect of MHI on postural stability in athletes. J. Athletic Training 31: , Guskiewicz, K.M., B.L. Riemann, D.H. Perrin, and L.M. Nashner. Alternative approaches to the assessment of mild head injury in athletes. Med. Sci. Sports Exerc. (in press). 11. Ingersoll, C., and C. Armstrong. The effects of closed head injury on postural sway. Med. Sci. Sports Exerc. 24(7): , Lehman, J., S. Boswell, R. Price, A. Burleigh, B. delateur, K. Jaffe, and D. Hertling. Quantitative evaluation of sway as an indicator of functional balance in posttraumatic brain injury. Arch. Phys. Med. Rehabil. 71: , Leinenger, B., S. Gramling, A. Farrell, J. Kreutzer, and E. Peck. Neuropsychological deficits in symptomatic minor head injury patients after concussion and minor concussion. J. Neurol. Neurosurg. Psychiatry 53: , Tangeman, P., and J. Wheeler. Inner ear concussion syndrome: Vestibular implications and physical therapy treatment. Top. Acute Care Trauma Rehabil. 1(1):72-83, Tuohimaa, P. Vestibular disturbances after acute mild head injury. Acta Otolaryngol. 359(87): 1-67, 1979.