Timed Oral Cognitive Tests Predict Brainstem Dysfunction Complaints

Background: Many neuropsychological tests have been validated for the assessment of cognitive function in multiple sclerosis (MS). While these tests are typically used to evaluate the underlying features of complex cognition, such as processing speed, attention, and language, the demands they place on speeded brainstem activity may give them additional clinical value as potential predictors of complaints related to brainstem dysfunction, such as dysarthria and dysphagia. Furthermore, these tests may be less appropriate measures for patients whose performance is rate-limited by difficulties with speech production.

Objectives: Examine the relationship between timed oral tests of cognition and complaints associated with brainstem dysfunction.

Methods: Patients who had undergone neuropsychological testing (N = 66) were examined via retrospective chart review. Patients completed orally administered neurocognitive measures as part of a neuropsychological battery. Kendall’s τ correlations were computed to examine the relationship between the neurocognitive measures and Incapacity Status Scale items on feeding and speech/hearing. Ordinal regressions examined predictive models of these disability items using three neurocognitive measures: the symbol digit modalities test (SDMT), Controlled Oral Word Association Test (COWAT), and the Stroop Color and Word Test.

Results: Significant correlations were noted between at least one brainstem disability item and six neuropsychological tests. Models using the SDMT, COWAT, and Stroop significantly predicted scores on both feeding (R² = .438, p = .001) and speech/hearing items (R² = .335, p = .001).

Conclusions: A strong predictive relationship exists between timed oral cognitive tests and subjective complaints of brainstem dysfunction. In patients with impaired production of speech, such tests may be skewed measures of cognitive function; however, such tests could possess previously unseen value as objective measurements of disordered brainstem activity.