PMC4365523_01
The instance of light cupula observed in the right hSCC. The patient's head and right hSCC were viewed from the top of the patient's head. (A) In the supine position, a left-beating nystagmus (maximal SPV = 33 /s) was persistently observed due to an utriculofugal deflection of the cupula. (B) When the patient's head was turned to the right while in the supine position, the right hSCC was activated because of an utriculopetal deflection of the cupula resulting in a persistent right-beating nystagmus (maximal SPV = 10 /s). (C) The cupula of the right hSCC was deflected utriculofugally when the head was turned to the left side, which caused a persistent left-beating nystagmus (maximal SPV = 53 /s). Note that the intensity of the nystagmus is stronger in left-head rolling than in right head-rolling. hSCC, horizontal semicircular canal; SPV, slow-phase velocity.
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PMC4365523_01_12901_2015_15_Fig1_HTML.jpg
Fig1
While in the supine position, a horizontal nystagmus beating toward the left side was persistently observed, and the maximal slow-phase velocity (SPV) was 33 /s (Figure 1A, Additional file 1). When the patient's head was turned to the right (Figure 1B, Additional file 2) or left (Figure 1C, Additional file 3) at 90  in the supine position, a geotropic DCPN continued persistently as long as the position was maintained.
The instance of light cupula observed in the left hSCC. The patient's head and the magnified left hSCC were viewed from the top of the patient's head. (A) In the supine position, a left-beating nystagmus (maximal SPV = 19 /s) was persistently observed due to an utriculofugal deflection of the cupula. (B) When the patient's head was turned to the right side, the left hSCC was inhibited because of the utriculofugal deflection of the cupula resulting in a persistent right-beating nystagmus (maximal SPV = 38 /s). (C) When the head was turned to the left side, the cupula of the left hSCC was deflected utriculopetally, which caused a persistent left-beating nystagmus (maximal SPV = 10 /s). Note that the intensity of the nystagmus is stronger in right-head rolling than in left head-rolling. hSCC, horizontal semicircular canal; SPV, slow-phase velocity.
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PMC4365523_01_12901_2015_15_Fig2_HTML.jpg
Fig2
When the patient's head was turned to the right (Figure 1B, Additional file 2) or left (Figure 1C, Additional file 3) at 90  in the supine position, a geotropic DCPN continued persistently as long as the position was maintained. In the supine position, a right-beating nystagmus was continuously observed, and the maximal SPV was 19 /s (Figure 2A, Additional file 4). When the patient's head was turned to the right (Figure 2B, Additional file 5) or left (Figure 2C, Additional file 6) at 90  in the supine position, a persistent geotropic DCPN was observed.