Original Paper Cerebrovasc Dis 2000;10:471–474 Accepted: February 21, 2000 Vertigo and Gait Ataxia without Usual Signs of Lateral Medullary Infarction: A Clinical Variant Related to Rostral-Dorsolateral Lesions Jong S. Kim Department of Neurology, University of Ulsan, Asan Medical Center, Seoul, South Korea Abstract Isolated vertigo and ataxia have not been reported as manifestations of lateral medullary infarction. The author describes 3 patients with lateral medullary infarction who presented with almost isolated vertigo and gait ataxia without usual signs/symptoms of lateral medullary infarction such as facial/hemibody sensory changes, dysphagia, hoarseness, hiccup, limb ataxia, and Horner sign. Brain MRI showed small infarcts selectively involving the most dorsolateral portion of the rostral medulla that corresponds to the vestibulocerebellar pathway. These patients illustrate that lateral medullary infarction may present as an isolated vertigo and gait ataxia. Clinicians should be aware of this clinical variant, because these patients may be misdiagnosed as having labyrinthine disorders. Copyright © 2000 S. Karger AG, Basel ABC © 2000 S. Karger AG, Basel 1015–9770/00/0106–0471$17.50/0 Fax + 41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Accessible online at: www.karger.com/journals/ced Introduction Recent MRI-clinical correlation studies have allowed us to understand various clinical syndromes of lateral medullary infarction (LMI) [1] which include unusual manifestations such as isolated trigeminal sensory symptoms [2, 3] or isolated dysphagia [3, 4]. However, isolated vertigo/gait ataxia caused usually by labyrinthine disorders or minor cerebellar strokes [5, 6] has not been considered as a manifestation of LMI. The author herewith reports 3 patients who presented almost purely with vertigo/dizziness and gait ataxia. This unusual presentation seems to be related to a selective involvement of the far dorsolateral portion of the rostral medulla that corresponds to the central vestibular pathways: superior portion of the vestibular nuclei and/or inferior cerebellar peduncle. Case Reports Patient 1 On awakening, this 64-year-old hypertensive man developed severe vertigo associated with nausea/vomiting and diplopia. Initially, he was unable to walk due to the vertigo/imbalance that was aggravated by head motion. He visited our department the next day. On examination, he was alert and oriented. There was a skew deviation of the eyes, i.e., hypotropia of the right eye, which was most promi- Jong S. Kim, MD Department of Neurology, Asan Medical Center Song-Pa, PO Box 145 Seoul 138-600 (South Korea) Tel. +82 2 2224 3442, Fax +82 2 474 4691, E-Mail jongskim@www.amc.seoul.kr Downloaded by: University of Hong Kong 198.143.53.1 - 2/2/2016 11:43:55 AM Key Words Cerebrovascular disease W Vertigo W Ataxia W Lateral medullary infarction Fig. 1. Patient 1. T2-weighted MRI showing a small infarct in the Fig. 2. Patient 2. T2-weighted MRI showing a small infarct in the dorsolateral portion of the right rostral medulla (arrow). dorsolateral portion of the left rostral medulla (arrow). nently observed on right-down gaze. Head tilting was not observed. Ocular movements were full, and there was torsional, left-beating nystagmus in both eyes. The eyeballs were slightly drifted to the right which was observed more clearly on eyelid reopening following eye closure. There were no signs of Horner syndrome, and no dysphagia, dysarthria, or hoarseness were noted. He did not develop hiccup or respiratory difficulties. The other cranial nerves were all within normal limits. Examination for pinprick, temperature, vibration, and position sensations did not reveal any abnormalities in the body/ limbs as well as in the face. The muscle strength was normal, and there was no limb ataxia on finger-to-nose or heel-to-shin test. On standing, he strikingly veered to the right. Routine laboratory tests including complete blood count, liver function tests, blood lipid levels, and ECG were within normal limits. Brain MRI performed 4 days later showed a small infarct in the far dorsolateral portion of the right rostral medulla (fig. 1). MRA (magnetic resonance angiography) showed mild stenosis of the right distal vertebral artery. Three days after onset, his diplopia resolved, and he was able to walk with slight unsteadiness. Two months later, he continued to have mild dizziness on walking, that aggravated on rapid turning of his body or head. nerves were all within normal limits. Examination for pinprick, temperature, vibration, and position sensations revealed no abnormalities in the body/limbs and the face. The muscle strength was normal, and there was no limb ataxia on finger-to-nose or heel-to-shin test. On standing, she veered to the left. Routine laboratory tests and ECG were within normal limits. Brain MRI taken 4 days after the onset of symptoms showed a small infarct in the most dorsolateral portion of the left rostral medulla (fig. 2). MRA showed normal findings. The severe vertigo and gait ataxia improved within 2 days. At 2 months of follow-up, there remained slight instability on tandem gait. 472 Cerebrovasc Dis 2000;10:471–474 Kim Downloaded by: University of Hong Kong 198.143.53.1 - 2/2/2016 11:43:55 AM Patient 2 A 56-year-old previously healthy woman suddenly developed vertigo associated with nausea/vomiting that aggravated on head movements. She was able to walk, but veered to the left. On examination the next day, she was alert and oriented. Ocular movements were full, and there was fine, right-beating nystagmus on right gaze. Skew deviation was not observed. She did not have dysphagia, dysarthria, diplopia, hiccup, hoarseness, or Horner syndrome. Other cranial Patient 3 A 68-year-old hypertensive man suddenly development vertigo and gait ataxia. He was unable to stand due to strong veering of his body to the left. However, he did not have diplopia, hoarseness, dysarthria, dysphagia, hiccup, or sensory symptoms. The vertigo abated within 3 days, but he continued to have dizziness and a sense of imbalance. He visited our clinic 7 days after the onset of the symptoms. Neurological examination showed that there were no Horner sign, dysarthria, hoarseness, and dysphagia. Tests for motor and sensory function were normal, and dysmetria and dysdiadochokinesia were not present. However, he slightly veered to the left on tandem gait. Routine laboratory tests including complete blood count, liver function tests, blood lipid levels, and ECG were within normal limits. MRI showed a small infarct involving the far dorsolateral portion of the left rostral medulla and medulla-pons junction (fig. 3). MRA revealed normal results. At 4 months of follow-up, he was able to walk normally, but complained of intermittent dizziness on sudden positional change. Fig. 4. Schematic presentation of important structures in the rostral medulla. the dorsolateral portion of the left rostral medulla and medulla-pons junction (arrows). Discussion The 3 patients described here presented with prominent vertigo and gait ataxia, but did not have usual symptoms/signs of Wallenberg’s lateral medullary syndrome such as facial/hemibody sensory changes, dysphagia, hoarseness, hiccup, limb ataxia, and Horner sign. Their only other neurological signs were nystagmus and skew deviation in patient 1 and gaze-evoked nystagmus in patient 2. Patient 3 was not examined by the author during the acute stage, and initial neurological findings were, therefore, unknown. However, it seems clear that he did not have dysphagia, hoarseness, and sensory symptoms. Our neuroradiological results suggest that the patients’ symptoms are caused by a selective involvement of the central vestibular pathways, i.e., the most superior portion of the vestibular nuclei and/or vestibulocerebellar pathway in the inferior cerebellar peduncle [7]. In the rostral medulla, these structures are located far dorsolaterally, relatively isolated from other structures (fig. 4), whereas they are closely related anatomically to the spinal trigeminal tract/nuclei in the caudal medulla [7]. Therefore, this variant of LMI may indicate the selective involvement of the far dorsolateral rostral medulla. Because sen- Vertigo and Ataxia due to Lateral Medullary Infarction Cerebrovasc Dis 2000;10:471–474 473 Downloaded by: University of Hong Kong 198.143.53.1 - 2/2/2016 11:43:55 AM Fig. 3. Patient 3. T2-weighted MRI showing a small infarct involving sory tracts and nucleus ambiguus are spared, these patients will not have disabling sequelae of LMI such as dysphagia or paresthesia [8], but may have long-lasting dizziness. To my knowledge, isolated vertigo/gait ataxia as a clinical manifestation of LMI has not been reported. Previously, Vuilleumier et al. [9] described 3 patients with similar symptoms. Their infarcts were restricted to a dorsal portion of the medulla. However, the lesions were extended from caudal to rostral medulla and involved the cerebellum as well. The larger-sized lesions than those of our patients may explain the presence of sensory symptoms in 2 of their patients. The 3rd of their patients (patient 21) had nearly isolated vertigo and gait ataxia without other LMI signs, but he additionally exhibited bilateral corticospinal tract signs for unknown reason. According to previous literature, the rostral, dorsolateral medullary area is supplied either by posterior group branches from the medial posterior inferior cerebellar artery or by lateral group branches from the vertebral artery [10]. In patient 1, occlusion of penetrating branches from the distal vertebral artery is suspected by the MRA finding of a stenotic distal vertebral artery. The exact vascular pathogenesis remains unknown in patients 2 and 3 who had normal MRA findings; MRA is insufficient in the evaluation of the posterior inferior cerebellar artery [11]. The oculomotor findings of patients 1 and 2 may also be explained by an involvement of the vestibular nuclei or vestibulocerebellar afferent fibers in the inferior cerebellar peduncle. According to Waespe and Wichmann [12], drift of the eyes to the side of the lesion in LMI patients is explained by an interruption of already crossed olivocerebellar fibers at the inferior cerebellar peduncle which leads to tonic shift in spontaneous firing rate of Purkinje cells and their vestibular target cells ipsilateral to the lesion. Finally, axial instability without the presence of limb ataxia could be explained by preferential involvement of the vestibulocerebellar and/or spinocerebellar fibers that are functionally related to axial motor controls [7]. In summary, our patients presented with almost isolated vertigo/gait ataxia due to dorsolaterally and rostrally situated small medullary infarcts, an observation that would broaden our understanding of the clinical spectra of LMI. Because these clinical symptoms may mimic labyrinthine disorders, this possibility should be considered and appropriate diagnostic investigations such as MRI be performed in suspected patients. 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