Focal areas of signal intensity in neurofibromatosis type 1: Correlation between MRI findings and cognitive function

Background

Focal areas of signal intensity (FASI) are T2-weighted hyperintensities detected on brain MRI in 43 %–93 % of children with neurofibromatosis type 1 (NF1). Their association with cognitive impairment, a common feature of NF1, remains controversial.

Objective

To investigate potential correlations between the presence, number, and location of FASI and cognitive performance in children with NF1.

Materials and methods

Brain MRIs and neuropsychological reports of 17 patients with NF1 (mean age 9.29 ± 3.7 SD) were retrospectively reviewed. Cognitive profiles were assessed using standardized Wechsler scales (WPPSI-III, WISC-III, WAIS-R).

Results

The mean Full Scale Intelligence Quotient (FSIQ) was 84 ± 14.54, within the borderline range; 11.76 % of patients had a diagnosis of Intellectual Disability (ID). A clinically significant discrepancy between Verbal and Performance Intelligence Quotient (PIQ) was observed in 64.7 % of patients, favoring PIQ. The mean number of FASI per patient was 3.94 ± 1.76. Pearson’s correlation revealed a non-significant inverse association between total FASI count and FSIQ (r = –0.12, p = 0.621). The cerebellum was the most frequently affected region (70.6 %). Patients with FASI in the cerebellum or brainstem had significantly higher PIQ than those with FASI elsewhere (p < 0.05). The two patients with ID both had thalamic FASI.

Conclusions

This exploratory study suggests that FASI location and number may be associated with cognitive variability in NF1, but larger studies are needed to confirm these trends.