PMC5434105_01
Video-head impulse test: the gain of the left horizontal VOR is decreased: 0.48, in contrast to a right horizontal VOR gain of 0.8 (normal: 0.8).
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F1
Otometrics, Taastrup, Denmark) demonstrated decreased left gain in two consecutive trials (0.48 and 0.59, normal range >0.80), whereas right vHIT gain was normal (0.80 and 0.95). Overt refixation saccades were present (Figure 1).
Head and neck computerized tomography angiogram: left upper panel: coronal view of the vertebrobasilar junction. The right superior V4 vertebral artery (VA) segment is visualized, and the origin of the right anterior inferior cerebellar artery (AICA) is observed. Retrograde flow fills the left VA. The left AICA is not visualized. Right upper panel: the left posterior inferior cerebellar artery (PICA) is imaged; it originates extra-cranially from the left V3/V4 VA and is normal, probably representing a PICA/AICA variant. Left lower panel: sagittal image of a normal left V2/V3 VA. Right lower panel: coronal view of a normal left V2/V3 VA.
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F2
Head and neck computerized tomography angiogram (CTA) showed occlusion of the V4 segment of the left vertebral artery (VA); a robust left PICA originated extradurally from the V3/V4 junction, proximal to the occlusion (Figure 2), the right VA was hypoplastic and 50% stenotic at its origin; the right AICA artery was patent, and the left was either hypoplastic or absent.
Axial diffusion-weighted image MRI 04-25-2014: serial consecutive MRI sections of the medulla, from left: caudal to right: pontomedullary junction: restricted diffusion is present in the left lateral medulla.
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F3
A brain MRI 2 days later demonstrated restricted diffusion (DWI) involving the left lateral caudal medulla with rostral extension to the pontomedullary junction, sparing the pons and the root entry of the vestibular nerve (Figure 3).
Transversal brainstem sections from caudal to rostral stained for Luxol fast blue to demonstrate the localization and extent of the stroke. (A-D) In each section, the ischemic core with total necrosis is outlined by dashed lines. Note that the left medial vestibular nucleus (MVN) and prepositus hypoglossi nucleus (PPH) are not included in the lesion (E,F). Detailed views of the white boxes in (E) are shown in Figures S1A,B,D in Supplementary Material. AMB, nucleus ambiguous; AP, area postrema; ARC, arcuate nucleus; CTT, central tegmental tract; DCN, dorsal cochlear nucleus; DMX, dorsal motor nucleus of the vagal nerve; DSC, dorsal spinocerebellar tract; GR, gracile nucleus; HST, hypothalamic-spinal tract; IA, internal arcuate fibers; IVN, inferior vestibular nucleus; MAO, medial accessory inferior olive; LCU, lateral cuneate nucleus; MCU, medial cuneate nucleus; ML, medial lemniscus; MLF, medial longitudinal fascicle; NV, trigeminal nerve; NVIII, vestibular nerve; NXII, hypoglossal nerve; PN, pontine nuclei; PO, principal olive; PT, pyramidal tract; RVLM, rostral ventrolateral medulla; SOL, solitary nucleus; STT, spinothalamic tract; VCN, central cochlear nucleus; VSC, ventral spinocerebellar tract; Vsp, spinal trigeminal nucleus; VII, facial nucleus; XII, hypoglossal nucleus.
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F4
A repeat brain MRI showed unchanged caudal left lateral medulla DWI restriction (Figure S4 in Supplementary Material).