The Tyndall Effect in High-Resolution Computed Tomography of Semicircular Canalolithiasis with Benign Paroxysmal Positional Vertigo.

To date, along with the progress of new technology and computer program development, the high-resolution computed tomography (HRCT) had been applied in different clinical application, such as HRCT for coronary angiography. In the current neuroimaging reports, we present HRCT images of the head/neck of two cases, in which one had a diagnosis of benign paroxysmal positional vertigo (BPPV) and the other did not, to represent the Tyndall effect, which describes the scattering of light by particles (i.e., semicircular canalolithiasis) in the path of light and enables clinicians to see a specific signal on the HRCT images. On the HRCT image of the patient with canalolithiasis with BPPV, we could obviously see the scattering effect (i.e., Tyndall effect) in the horizontal/posterior semicircular canal; however, on the HRCT image of the other without canalolithiasis, we could not see such findings. Therefore, through the assistance of technological progress, HRCT might be beneficial in the diagnosis of semicircular canalolithiasis, which has the advantage of being noninvasive and having a low risk of complications. However, because of the disadvantages of expense and risk of radiation exposure, HRCT should be reserved for patients who are difficult to diagnose.