Plasma endothelin level in the acute stage of Bell palsy

To determine the plasma endothelin level in the acute stage in patients with Bell palsy (based on the hypothesis that endothelin, which is a potent vasoconstrictor, may play a role in the mechanism of the onset of facial nerve paralysis and in view of the fact that the etiology of Bell palsy is still a maze of unknowns).

The study involved 62 patients with the acute stage (tested within 10 days of onset) of Bell palsy (i.e., idiopathic acute peripheral facial paralysis) and an additional 36 healthy persons who served as control subjects. To determine the content of endothelin, 2 ml of plasma samples was collected from each subject. Endothelin-1 was extracted and analyzed by a radioimmunoassay by using anti-endothelin-1 antibody.

Nihon University Itabashi Hospital, a referral and institutional center in Tokyo, Japan.

The patients who were suffering from Bell palsy exhibited a statistically significant (P < .01) increase in the endothelin level compared with that in the 36 normal control subjects. An age-matched comparison (ranges, 20-29 years and 30-39 years) of patients with Bell palsy with normal control subjects revealed a significant difference between the normal group and the group with Bell palsy in the plasma endothelin level for both age groups that were tested (P < .01). The mean value of the endothelin level in patients with Bell palsy was maximal on day 5, and the percentage of patients with abnormally elevated endothelin levels was 100% from days 6 to 9.

Endothelin, which has potent vasoconstrictive effects, may contribute to the pathogenesis of the microcirculatory impairment that occurs in patients with Bell palsy, mainly by promoting secondary ischemia.