Factors Associated with No or Insufficient Temporal Bone Window Using Transcranial Color-coded Sonography

Purpose Transcranial color-coded sonography (TCCS) noninvasively assesses physiologic and pathologic intracranial blood flow especially in non-Caucasians who have high prevalence of intracranial steno-occlusive arterial disease. However, a higher temporal bone window failure (WF) rate is found in non-Caucasians and thus limits the utilization of TCCS. This study was performed to explore the associated factors of temporal bone WF in Taiwanese patients. Methods Between January 2014 and June 2014, 355 consecutive patients who received TCCS examination during their hospitalization at neurological ward were enrolled in this study, including 218 men and 137 women. Patients were classified into two groups, one with no or insufficient temporal bone window and the other with good temporal bone window for identification of middle, anterior, and posterior cerebral arteries via transtemporal approach. Age, sex, and conventional vascular risk factors in each group were compared. Results It was found that 28.8% of the patients had no or insufficient temporal bone window. Among them, 20.3% had complete bilateral temporal bone WF. For all factors studied, older age and female sex were significantly associated with no or insufficient temporal bone window. Conclusion The failure rate of temporal bone window was considered high as compared to Western countries but, not surprisingly, age and sex remained the significant factors. Introducing echo contrast agents during the TCCS examination might help to increase the success rate of TCCS examination and provide useful information to clinicians.