CT evaluation of sigmoid plate dehiscence causing pulsatile tinnitus.

OBJECTIVES

To evaluate the characteristics of sigmoid plate dehiscence (SPD) causing pulsatile tinnitus (PT) on CT arteriography and venography (CTA + V).

METHODS

Thirty PT patients treated successfully with SPD reconstruction were enrolled. Sixty asymptomatic patients were matched. The location, extent, number of SPD cases and concomitant signs, including venous outflow dominance, transverse sinus stenosis, high jugular bulb, temporal bone pneumatization, height of pituitary gland and pituitary fossa, abnormal mastoid emissary vein, were detected and compared using CTA + V.

RESULTS

More than one SPD was found on the symptomatic side in 13/30 PT patients (43.3 %). The upper segment of the sigmoid plate was involved in 29/44 SPDs in the vertical direction (65.9 %); the lateral wall was involved in 38/44 SPDs in the horizontal direction (86.4 %). Singular SPD was detected in 3/60 asymptomatic patients (1.67 ± 0.35 mm(2)), less so in PT patients (7.97 ± 5.17 mm(2)). Compared with the control group, ipsilateral venous outflow dominance, high jugular bulb and bilateral transverse sinus stenosis were more common in the PT group, together with deeper pituitary fossa and flatter pituitary glands.

CONCLUSION

SPD causing PT has characteristic CT findings. It may be generated by vascular or intracranial pressure abnormalities and act as a common key to triggering PT's perception.

KEY POINTS: Pulsatile tinnitus (PT) caused by sigmoid plate dehiscence (SPD) may be cured. SPD causing PT has some characteristic findings on CT. SPD may be a common key to triggering PT's perception. Thin-slice high resolution CT venography is recommended for SPD assessment. The relationship between intracranial pressure and SPD causing PT should be studied.