Clinical Neurology and Neurosurgery 118 (2014) 80–82 Contents lists available at ScienceDirect Clinical Neurology and Neurosurgery journal h om epa ge : www.elsevier.com/locate/clineuro Evolution of torsional-upbeat into hemi-seesaw nystagmus in medial medullary infarction Sun-Uk Lee a,1 , Seong-Ho Park b,1 , Seong-Hae Jeong c , Hyo-Jung Kim d , Ji-Soo Kim b,∗ a Department of Neurology, Ajou University School of Medicine, Ajou University Hospital, Suwon, South Korea b Department of Neurology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea c Department of Neurology, Chungnam National University Hospital, Daejon, South Korea d Kangwon National University College of Medicine, Biomedical Research Institute, Seoul National University Bundang Hospital, Seongnam, South Korea a r t i c l e i n f o Article history: Received 16 November 2013 Received in revised form 28 December 2013 Accepted 2 January 2014 Available online 14 January 2014 Keywords: Vertigo Nystagmus Hemi-seesaw nystagmus Medullary infarction 1. Introduction Hemi-seesaw nystagmus refers to mixed torsional-vertical jerky nystagmus with conjugate torsional components and the vertical components in the opposite directions [1]. Based on the evolution of upbeat into jerky seesaw nystagmus in a patient with medial medullary infarction (MMI) [2], disruption of the vestibulo-ocular reflex (VOR) pathways from the vertical semicircular canals was proposed as a mechanism of hemi-seesaw nystagmus. This pre- sumption was supported by following reports on jerky seesaw nystagmus in patients with internuclear ophthalmoplegia (INO) from lesions involving the MLF which is believed to carry the fibers for the vertical VOR originating from the contralateral vertical canals [3,4]. The authors have proposed three distinctive patterns of mixed torsional-vertical jerky nystagmus according to the ver- tical VOR pathways involved [3,4]. Herein, we describe evolution of torsional-upbeat nystagmus into hemi-seesaw nystagmus in a patient with MMI. This evolution provides further evidence that ∗ Corresponding author at: Department of Neurology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do 463-707, South Korea. Tel.: +82 31 787 7463; fax: +82 31 719 6828. E-mail address: jisookim@snu.ac.kr (J.-S. Kim). 1 These authors equally contributed to this work. hemi-seesaw nystagmus results from disruption of the vertical VOR pathways. 2. Case report A 62-year-old woman with hypertension and diabetes mel- litus for 6 years developed sudden vertigo. She showed left hypertropia and spontaneous nystagmus with mixed leftward, counter-clockwise torsional (the upper pole of the eyes beating to the left ear) and upbeat components. Spontaneous nystagmus measured with video-oculography (VOG) was mainly upbeating in the right eye and mostly torsional in the left eye (Video 1). This pattern of nystagmus did not change during horizontal or vertical gazes. Gaze-evoked nystagmus was present during lateral gazes. She also showed rightward ocular lateropulsion. Horizontal head impulse test was normal in both directions. Remainder of the neu- rological examination was unrevealing without tongue deviation, hemiparesis or sensory changes. MRI and MR angiography showed an acute infarction in the left rostral medial medulla with hypoplastic left vertebral artery (Fig 1A and B). Fundus photography showed clockwise (from the patient’s perspective) contraversive torsion of the eyes (23.6 ◦ in the right eye, –7.4 ◦ in the left eye, normal range: 0–12.6 ◦ , negative value indicates intorsion, Fig. 1C). She also showed contraversive rightward tilt of the subjective visual vertical (SVV, 11.0 ◦ in the right eye, 11.1 ◦ in the left eye, normal range: –3.1 ◦ to 3.0 ◦ , positive value indicates rightward tilt). The results of bithermal caloric tests were normal. 0303-8467/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.clineuro.2014.01.003