PMC9868901_01
(A, B) Cranial computed tomography (CT) demonstrates no abnormality in the brain tissue. (B) A leftward conjugate ocular deviation is observed while the eyes are closed (white arrow).
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Cranial computed tomography (CT) performed immediately upon arrival to the ED did not provide any (imaging) evidence for ischemia or hemorrhage of the brainstem and cerebellum (Figure 1). However, CT revealed leftward conjugate ocular deviation upon closing the eyes (Figure 1B).
(A-C) Diffusion-weighted magnetic resonance imaging (DWI) of the patient. (A) No abnormal signal is observed in the vestibular nucleus of the pons. (B) Acute infarction in the medial medulla, which involves the nucleus prepositus hypoglossal (NPH) (white arrow). (D) Cranial computed tomography angiography (CTA) of the patient demonstrates total occlusion of the left intracranial vertebral artery (ICVA), which represents the offending vessel.
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Subsequently, he underwent cranial magnetic resonance imaging (MRI), which revealed an acute infarct confined to the right side of the medial medulla (Figures 2A-C). Cervical and cranial CT angiography revealed occlusion of the left vertebral artery at the V4 segment (Figure 2D).
(A) Without visual fixation, the patient demonstrates spontaneous right-beating nystagmus with a linear nystagmus waveform and a mean slow-phase velocity (SPV) of 7.7 /s, which decreases during visual fixation, with a mean SPV of 1.6 /s. (B) Nystagmus in all gaze directions is similar with spontaneous nystagmus, and is more intense upon staring to the right. (C) Results of the video-oculography-based HIT (vHIT) (RHC, right horizontal semicircular canal; LHC, left horizontal semicircular canal). The vHIT results demonstrate numerous corrective saccades in the left horizontal semicircular canal, but the VOR gain is in the normal range, thereby suggesting damage in the central nervous system. vHIT examination of the bilateral anterior semicircular canal and posterior semicircular canal reveals no abnormality.
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The patient exhibited spontaneous right-beating nystagmus with a mean slow-phase velocity (SPV) of 7.7 /s, which decreased during visual fixation, with a mean SPV of 1.6 /s (Figure 3A). Nystagmus was identical to spontaneous nystagmus in all gaze directions but was more intense upon gazing to the right (Figure 3B). HIT recording using the ICS Impulse system revealed a normal gain in the vestibulo-ocular reflex (VOR) (0.99 for the right horizontal canal and 0.84 for the left horizontal canal; normal value >0.80), and numerous consistent covert corrective saccades were captured upon turning the head to the left side (Figure 3C).