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Show Journal of Neuro- Ophthalmology 21( 3): 219- 220, 2001. © 2001 Lippincott Williams & Wilkins, Inc., Philadelphia Photo Essay Downbeat Nystagmus Associated with Caudal Brainstem Compression by the Vertebral Artery Andrew G. Lee, MD An 87- year- old white man presented with a one- year history of oscillopsia owing to primary position down- Manuscript received June 6, 2001; accepted June 20, 2001. From the Departments of Ophthalmology, Neurology, and Neurosurgery, The University of Iowa Hospitals and Clinics, Iowa City, Iowa. Address correspondence and reprint requests to Andrew G. Lee, MD, 200 Hawkins Drive PFP, Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA 52242. This work was supported in part by an unrestricted grant from Research to Prevent Blindness, Inc., New York, NY. beat nystagmus. Visual acuity was 20/ 20 OU. Pupils, slit- lamp biomicroscopy, visual- field testing, intraocular pressure, and ophthalmoscopy were normal OU. Motility examination showed full versions, and the patient was orthotropic in the diagnostic positions of gaze. In primary position, he had low amplitude, low- frequency downbeating nystagmus. The amplitude and frequency of the downbeat nystagmus were maximal in downgaze and lateral gaze and minimal in upgaze. He was not taking lithium or any other medications. Magnetic resonance imaging of the head revealed compression of the FIG. 1. A: Axial T2- weighted magnetic resonance imaging ( MRI) shows compression of the medulla ( arrow) by the vertebral artery. B: Sagittal Tl- weighted MRI shows distortion of the caudal brainstem by the vertebral artery flow void ( arrow). 219 220 A. G. LEE caudal brainstem by the vertebral artery ( Fig. 1). He declined any intervention. Downbeat nystagmus is often owing to a lesion at the cervicomedullary junction ( e. g., Chiari malformation, platybasia, basilar invagination, Paget's disease). Other causes for downbeat nystagmus include medicines ( e. g., lithium), deficiencies of magnesium or B12, alcohol-related disease ( e. g., Wernicke's, cerebellar degeneration), demyelination, infarction, hereditary and familial cerebellar degeneration, and neoplasm. Downbeat nystagmus attributable to dolichoectatic vertebral arteries and brainstem compression is rare. Himi et al. ( 1) reported a case that improved after neurovascular decompression. Krespi et al. ( 2) reported a case with distortion of the anterolateral medulla by vertebrobasilar dolicho-ectasia. Jacobson and Corbett ( 3) reviewed 41 cases of downbeat nystagmus and found two cases of dolicho-ectasia of the vertebral artery. Clinicians should be aware that caudal brainstem compression owing to vertebral artery dolichoectasia may cause downbeat nystagmus. REFERENCES 1. Himi T, Katuara A, Tokuda S, et al. Downbeat nystagmus with compression of the medulla oblongata by the dolichoectatic vertebral arteries. Am J Otol 1995; 16: 377- 81. 2. Krespi Y, Verstichel P, Masson C, et al. Downbeat nystagmus and vertebrobasilar arterial dolichoectasia. Rev Neurol 1995; 151: 196- 7. 3. Jacobson DM, Corbett JJ. Downbeat nystagmus associated with dolichoectasia of the vertebral artery. Arch Neurol 1989; 46: 1005- 8. / Neuro- Ophthalmol, Vol. 21, No. 3, 2001 |
