| Summary: | Introduction-Physical activity can reduce the risk of contracting many of the 'diseases of the
sedentary', such as coronary heart disease and cancer (Blair et al., 1996). Recognition of this
protective effect has led to the development of many programmes designed to promote the
benefit of participation in sport and physical exercise (Hillary Commission, 1993; Nicholl et
aI., 1995). With participation in sport, especially contact sport, the risk for injuries increases,
including injuries to the head and neck (Wilberger, 1993; Wekesa et al., 1996; Pettersen,
2002).
Mild traumatic brain injuries (MTBI) or concussion as used interchangeably in the literature
(Maroon et al., 2000; Wills & Leathem, 2001) are an important public health concern, due to
the high incidence and frequently persisting symptomatology (Evans, 1992). Mild traumatic
brain injury is defined as a complex patho-physiological process affecting the brain induced
by traumatic biomechanical forces (Aubry et al., 2002; McCrory et al., 2004). A sub-concussive
injury or very mild traumatic brain injury (vMTBI) may be defined as an apparent
brain insult with insufficient force to cause hallmark symptoms of concussion (Jordan, 2000;
Webbe & Bath, 2003).
The high incidence of sport related head injuries in South Africa is alarming, although the
prevalence thereof is unknown and difficult to assess, as the seemingly trivial injuries
frequently remain unreported (Roux et al., 1987). This is especially applicable in sport where
a milder form of head injury is common. This is cause for concern as cumulative head
injuries traditionally regarded as trivial or 'minor' may result in players running the risk of
increasingly negative consequences following repetitive 'minor' head injuries. In contact
sport such as rugby, players are at great risk of sustaining repetitive mild traumatic brain
injuries. The negative outcome following these repetitive minor head injuries has been
demonstrated by numerous studies on boxers and other athletes exposed to repeated MTBI
and vMTBI (McLatchie et aI., 1987). The incidence of vMTBI has not yet been researched in
school rugby and this study is the first to report the incidence of vMTBI in a secondary
school rugby team.
Obiectives - The objectives of this study were to determine the incidence, the
neuropsychological consequences and the effect on the academic performance of repeated
mild (MTBI) and very mild traumatic brain injuries (vMTBI) in a secondary school rugby
team during one playing season.
Methods - A cohort of 35 secondary school male rugby players divided into a vMTBI (group
1) (n=26) and a MTBI (group 2) (n=9) from a local secondary school's first and second team,
was followed for a full competitive season by a trained Biokineticist, who was present at all
the games and contact sessions played. All vMTBI and MTBI and the severity of these
injuries were documented. A control (group 3) that consisted of 10 secondary school non-rugby
players were compared with the vMTBI and MTBI groups.
The incidence of repeated MTBI and vMTBI in a secondary school rugby team were gathered
by questionnaires and observation next to the field by a trained Biokineticist. Pre-season and
post-season neuropsychological tests were conducted on the research groups and the control
group. The neuropsychological tests that were conducted on the three groups were the Colour
Trial Test 1 and 2 (CTT 1 + 2), the Symbol Digit Modalities Test (SDMT), the Wechsler
Memory Scale-Revised (WMS-R) and the Standardised Assessment of Concussion (SAC).
After each match played throughout the season the research group also completed a SAC test.
The academic results of the final examination (year 1) of the year of the specific rugby season
were obtained, as well as the academic results of the final examination of the preceding two
years (year 2 and 3).
The programme STATISTICA (version 7.0, Stat soft, Tulsa, OK) was used to analyse the
data. Descriptive statistics, one-way ANOVA's, two-way repeated measures ANOVA's,
Post-hoc Tuckey HSD analysis and Pearson's product moment correlation were used for all
the statistical analyses.
Results - This study of a secondary school rugby team has shown 726 vMTBI's and 18
MTBI's throughout one rugby season. This relates to 1951 vMTBI's per 1000 player hours
and 48 MTBI's per 1000 player hours. Reductions in delayed memory (p=O.O1)from preseason
to post-season in a group of players with repetitive vMTBI's during a single rugby
season were found. This was the first evidence of possible neurocognitive deficits towards
delayed memory in very mild traumatic brain injuries at secondary school level. Statistically
significant (p<=0.05)results of the SAC test totals between both the vMTBI and MTBI groups
were documented in the different games throughout the rugby season and compared with the
baseline test. No statistically significant differences (p<=0.05) between the pre-season and
post-season's scores of the SAC test totals were documented. A decrease in academic
performance in the subject Afrikaans (year 1 compared with year 2) with a p-value of
p=O.O17(group 1) and p=O.O16(group 2) respectively was found.
Conclusion - The findings of this study indicate a high incidence of vMTBI in a cohort of
secondary school rugby players in one season, a statistically significant reduction (p=O.O1 )in
delayed memory of the vMTBI rugby players and a statistically significant decrease in
academic performance p=O.O17 (group 1) and p=O.O16 (group 2) in the subject Afrikaans
from year 1 to year 2 final examinations. === Thesis (Ph.D. (Human Movement Science))--North-West University, Potchefstroom Campus, 2006.
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