Date Published: July 13, 2017
Publisher: Public Library of Science
Author(s): A-Ching Chao, Ke Han, Feng-Chi Chang, Hung-Yi Hsu, Chih-Ping Chung, Wen-Yung Sheng, Lung Chan, Jiang Wu, Han-Hwa Hu, Hong-Liang Zhang.
Accurate diagnosis of subtypes of transverse sinus (TS) hypoplasia requires more expensive methods like magnetic resonance (MR) imaging. We hypothesized ultrasound findings of the internal jugular vein (IJV) can be surrogate indicators for diagnosis of TS hypoplasia. MR images were reviewed in 131 subjects to evaluate TS diameter and the location and degree of venous flow stenosis and obstruction. Ultrasound parameters including the cross-sectional lumen area (CSA), time-average-mean velocity (TAMV), and flow volume (FV) at each IJV segment were also evaluated. Sixty-nine subjects had TS hypoplasia based on MRV criteria, of which 39 TS hypoplasia were considered a subtype of TS hypoplasia, which is secondary to the downstream venous compression/stenosis or left brachiocephalic vein. In the ultrasound study, the CSA of the IJV ipsilateral to TS hypoplasia was significantly smaller. Further, a contralateral/ipsilateral IJV CSA ratio >1.55 provided good sensitivity, specificity, and positive predictive value for discriminating TS hypoplasia.
Asymmetry of the transverse sinus (TS) is a common finding with unilateral hypoplasia or aplasia in 20–39% of cases, and was previously considered to be a normal anatomical variation [1–3]. However, increasing evidence suggests that asymmetry of the TS is associated with the manifestation and progression of a number of neurological disorders [4–7]. Adverse neurological effects that have been associated with TS hypoplasia include: a prolonged cerebral circulation time and impaired cerebral autoregulation linked to postcarotid-stenting hyperperfusion syndrome , severe brain edema in middle cerebral artery infarction as a result of increased venous outflow resistance , high-altitude headache , and white matter hyperintensities in patients with Parkinson’s disease . Thus, TS hypoplasia is increasingly considered to be an abnormality that significantly affects cerebral hemodynamic regulation.
A total of 131 subjects (90 patients and 41 controls; 70 men and 61 women; mean age, 54.0 ± 15.1 years; age range, 17–86 years) were enrolled in the present study between the years of 2008 and 2012. The detailed distribution of subjects with and without TS hypoplasia was reported in Table 1 of our previous paper . In summary, 38% (17), 33% (8), 43% (9) and 68% (28) of the subjects with TGA, TMB, panic disorder, and controls, respectively, are with no TS hypoplasia.
In conclusion, IJV flow profiles on ultrasound appear to provide reliable detection of TS hypoplasia, but future work is required to optimize this imaging modality for the differentiation of TS hypoplasia subtypes. Additionally, we observed indicators of upstream intracranial venous hypertension in subjects with anatomical TS hypoplasia. Future work is needed to clarify the clinical implications of each subtype of TS hypoplasia.