Abstract
Bilateral symmetrical pontine hyperintensities (PHI) on MRI are occasionally observed in the elderly. Pullicino et al. reported that a Binswanger's disease-like pathology was presented in this lesion, and concluded that this was the cause of the PHI. They designated the lesion as pontine ischemic rarefaction (PIR). To clarify the clinical meaning of PIR, we investigated the risk factors of PHI and examined the correlation between PHI and supratentorial changes. We selected 86 subjects with PHI by 0.5-tesla MRI over the period from March 1995 to February 1996. Wallerian degeneration and PHI combined with pontine hemorrhage were excluded. Patients with hyponatremia and alcoholism were also excluded. We classified the PHI into 3 groups : bilateral symmetrical (BS) (N=42), unilateral (U) (N=20), and bilateral asymmetrical (BA) (N=24). We compared the supratentorial changes among them (Kruskal-Wallis test, and chi-square test). The supratenotorial changes consisted of cerebral hyperintense signal abnormalities, cortical atrophy and ventricular dilatation.
We examinated the contribution of arteriosclerotic risk factors (age, sex, diabetes mellitus, hypertension, and hyperlipidemia) to each group (multiple logistic test). The severity of periventricular hyperintensity (PVH) was different among the groups (Kruskal-Wallis test, p = 0.023), and it was higher in group BS than in group U (Scheffe's test, p < 0.05). In group BS, the age of the subjects was higher (mean ± SD, 79.6 ± 8.2) and the ratio of hypertensive patients was lower than in the others (p <0.05). There were no risk factors to discriminate group BA from the others. Through comparison among the pontine hyperintensities, group U can be said to represent infarction because of the laterality and correlation to arteriosclerotic risk factors. PIR (group BS) was noted in higher aged and less hypertensive subjects and had a correlation with PVH.
