Acute versus Chronic Lesions

The impact of the recency of the lesion on cognitive impairment has been discussed by early researchers of V-P differences in patients with unilateral lesions as a likely intervening variable in many studies (Fitzhugh, Fitzhugh, & Reitan, 1961; Klove & Fitzhugh, 1962). These investigators felt that failure to control for the acuteness versus the chronicity of the left or right lesions probably accounted for the negative findings in the literature. Specifically, they hypothesized that acute (new) lesions are more likely than chronic (long-standing) lesions to lead to predictable V-P discrepancies for patients with unilateral brain damage. This hypothesis is consistent with a bulk of clinical and research findings (Lezak, 1995) that stress that "the recency of the insult may be the most critical factor determining the patient's psychological status" (p. 282).

Fitzhugh et al.'s Study

Fitzhugh et al. (1962) systematically evaluated the acute-chronic dimension and found significant V-P discrepancies in the predicted direction only for their sample of patients with acute lesions; the differences for the chronic patients, though in the anticipated direction, were just 2 to 4 points.

Although Fitzhugh et al.'s study is often cited as evidence for the impact of the recency of brain damage on Wechsler test patterns, their samples of acute and chronic patients differed on numerous other variables as well: institution (acute patients were at a university medical center, chronic patients at a state hospital); gender (acute patients were predominantly male, chronic patients included a majority of females); nature of brain damage (acute injuries were almost all strokes, tumors, or head injuries, whereas chronic patients had convulsive disorders due to a wide variety of causes); education level (acute patients had an average of 8 years of education; chronic patients had an average of 5 ¡2 to 6 years); and IQ level (acute patients had mean FS-IQs of about 85; chronic patients had mean FS-IQs of about 70). Based on the previous discussion of gender differences, that variable alone might have accounted for the different V-P findings for the acute and chronic patients.

Aggregated Data from Several Samples

Table 8.8 was compiled from Fitzhugh et al.'s (1962) investigation and two additional studies (comprising four samples in all) that examined acuteness versus chronicity as an independent variable. The combination of data from these diverse samples should give more insight into the importance of this variable than is provided by Fitzhugh et al.'s unmatched samples. The data from the two samples of patients who have had strokes investigated by Inglis, Ruckman, Lawson, MacLean, & Monga (1982) are of particular value because the samples of acute and chronic patients were carefully matched on the variables of gender (by treating males and females separately), age, education (exception: chronic males with left lesions were much more educated than acute males with left lesions), familial lefthandedness, and severity of lesion.

Fitzhugh et al. (1962) did not specify how soon after the brain lesion the group with "recently developed symptoms of cerebral dysfunction" (p. 306) were tested, but they noted that the chronic sample was tested about 25 years following the first noted seizure. Todd et al. (1977) used a 1-year cutoff to determine acuteness and chro-nicity; all patients who were tested on the WAIS within 1 year of brain damage were designated as acute, while those tested 13 or more months following damage were classified as chronic. In Ing-lis et al.'s (1982) study, the acute samples had suffered a stroke within 6 months of testing (mean = 3 months), and the chronic groups had had a stroke 1-12 years prior to testing (mean = 4 years).

As indicated in Table 8.8 for the composite samples, left-brain-damaged patients with acute lesions and with chronic lesions both had a P > V difference of about 2 ¡4 points. Among right-

Table 8.8 V-P IQ discrepancies for patients with acute and chronic lesions lateralized to the right or left hemisphere

Study

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