[Clinical evaluation of the styloid process by plain radiographs and three-dimensional computed tomography]

To investigate the relation between radiological and clinical diagnosis for Eagle's syndrome and to evaluate the value of plain radiograph (PR) and three-dimensional CT reconstructional image (3-DCT) of styloid process (SP).

The length of the 144 SPs from the PR was recorded and the palpation of the SP in tonsillar fossa was carried out in 113 patients with suspective Eagles syndrome. Twenty-three of 113 patients also underwent 3-DCT, so that the length and angulation of the 30 SPs were measured.

Seventy-eight of 113 patients (31 men and 47 women) were diagnosed as having Eagles syndrome. The age ranged from 32 to 68 years (average age: Forty-two years). A good agreement between the PR and the palpation was determinated, Kappa coefficient was 0.58. The difference value of the length of 30 SPs between the PR and the 3-DCT was (1.59 +/- 1.32) mm, and there were statistically significant difference of the length (t = 6.64, P < 0.01) on the length of SP between the PR and the 3-DCT. Positive correlation between the PR and the 3-DCT was found to be statistically significant (r = 0.982 4 +/- 95% confidence interval: 0.9631, 0.9917). The mean of medial angle of SPs was (25.60 +/- 2.56) degrees in patients with positive palpation and (15.42 +/- 2.79) degrees in those with negative palpation, respectively (P < 0.01) and the mean of anterior angle of SPs was (16.86 +/- 4.83) degrees in patients with positive palpation and (12.71 +/- 3.39) degrees in those with negative palpation, respectively (P < 0.01). The abnormal medial and anterior angles of unilateral SP without more than 30mm long was also objectively diagnostic of SPS in 8 patients with positive palpation. Four patients, whose elongated SP is too tenuous to be palpated preoperatively, underwent intraoral styloidectomy because of the fact that 3-DCT showed the tip of SPs medial and anterior deflexion.

Despite magnifying image, the PR of SP is enough to diagnose Eagle's syndrome for the majority of cases. 3-DCT allows precise measurement of the length and the angulation of SPs, it is the best for the complementary purpose to the PR and to the selection of surgical approach in some cases.