Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT)

Address correspondence to: Mark Lovell, Ph.D., UPMC Sports Concussion Program; Department of Orthopaedic Surgery; Center for Sports Medicine; 3200 South Water Street, Pittsburgh, PA 15203.

Although it can be argued that the term impairment simply refers to a negative change in function, for most people the term carries much more serious connotations. This is a particularly important issue when working with people who have sustained mild injuries or disease processes that could have affected their brains. Neuropsychologists must guard against iatrogenesis (i.e., health care providers making the problem worse). It is quite possible that by over-pathologizing test scores, the health care provider can inadvertently make the patient worse. Focusing, dwelling, and worrying about symptoms and "brain damage" can magnify them and protract the recovery period. Having stated this, it is important to accurately detect change that has occurred, and to determine whether this is a statistically and clinically meaningful change.

A basic conceptualization of initial level of performance is provided below. Standardized tests yield scores that fall within certain classification ranges. The following classification ranges and their corresponding percentile rank ranges are commonly used, although not universally accepted: Mildly Impaired < 2nd percentile; Borderline 3rd - 9th percentile; Low Average 10th - 24th percentile; Average 25th - 75th percentile; High Average 76th - 90th percentile; Superior 91st - 98th; Very Superior > 99th percentile. Thus, if an individual obtained a score at the 42nd percentile, this would mean that his performance would be greater than or equal to 42% of his same-aged peers in the general population, and that his score would fall in the Average classification range.

Different normative scores and their corresponding descriptors (i.e., their classification ranges) are illustrated in Table 2. It is important to note that there is not precise agreement in our profession as to where exactly the cutoffs should fall between certain classification ranges (e.g., some may call a percentile rank of 9 low average instead of borderline, because it corresponds to an IQ of 80). There is also disagreement as to the three "impaired" classification ranges. The system below is similar to the more traditional IQ classifications corresponding to mild, moderate, and severe mental retardation.

Table 2. Normative scores and classification ranges in neuropsychology