Journal of Korean Medical Science Vol. 11, No. 2, 193-196 April 1996 Bilateral Medial Medullary Infarction Manifested as Sensory Ataxia: A case Report and Review of the Literature Jae-Kyu Roh, Yong-Seok, Lee Department of Neurology, Seoul National University Hospital, Seoul, Korea Medial medulary infarction is usually manifested as hypoglossal palsy, limb weakness, impairment of proprioception, and oculomotor disturbance. We report a case with the unusual presentation of sensory ataxia. A 71 year-old male presented with ataxia and disequilibrium. Bilateral dysmetria, truncal ataxia, Upbeat nystagmus, and impaired vibration and position sense were the clinical features. However, weakness of the limbs, tongue, or face was not definite. MRI revealed bilateral lesion in the medullary tegmentum, and cortical potentials of somatosensory evoked response were absent. Recovery was fair after treatment According to the literature, motor weakness is a cardinal manifestation in medial medullary infarction, and there has been no reported case presented as sensory ataxia preserving motor power. Current development of diagnostic tools would contribute to define a variety of clinical manifestations, topography, vascular concomitants, and prognosis in medial medullary infarction. Key Words: Cerebral infarction, Cerebrovascular cisorders, Medulla oblongata, Medial medullary syndrome, Ataxia INTRODUCTION Infarction of the medial medulla has been known to be a rare clinical entity of cerebrovascular diseases (Davison, 1937; Davison, 1944). It is ascribed to occlusion of the anterior spinal artery (ASA), or penet- rating branches of vertebral or basilar arteries (VBA). Well-known manifestations are ipsilateral weakness of the tongue, contralateral hemiparesis, contralateral im- pairment of proprioception, and oculomotor disturb- Address for correspondence : Jae-Kyu Roh, Department of Neurology, Seoul National University Hospital, Yeonkeon- dong 28, Chongro-gu, Seoul 110-744, Korea. Tel : 82-02-760-3265, Fax: 82-02-744-1785. 193 ance. However, it may be difficult to make a clinical diagnosis if some of these features are missing. Modern development in MR imaging has contributed to the detection of smaller lesions of the brainstem (Sawada et al., 1990), and the detection of cases with medial medullary infarction is increasing. The clinical features of our patient were atypical compared with previous reports, so the case here is presented with an extensive review of previous literature (Table 1). A new classification of medial medullary syndrome based on vascular territory, cause, symptoms, and its prognosis will be discussed. CASE REPORT A 71 year-old right-handed man was admitted due to severe ataxia and disequilibrium. Two days 194 before admission, he had felt numbness on both upper extremities. Next morning, he had had diifficul- ties in standing and walking due to severe disequilib- tium. He had a history of right hemiparesis and hemianesthesia 5 years before. Some medications had been prescribed for hypertension, anginapectoris, chronic azotemia and hyperuricemia. He has been J. -K. Roh, Y. -S. Lee smoking about a pack of cigarettes per day for the past 20 years. His father and brother died from strokes. On initial physical examination, the heart thythm was regular and murmurs were absent. He was alert and oriented. Pupils were isocoric and light reflex was prompt. Extraocular movements were full, but up-beating vertical nystagmus was present during Table 1. Vascular territories and neurologic deficits in medial medullary infarction (analysis of 15 reported cases) Author, Vascular Motor “Tongue ——~Proprioceptive Oculomotor Course year ay territory weakness weakness _dysfunction disturbance Davison R)ASA LHemi (+) (+) Horizontal(N) Died (1937) R)FP B)CGP* 10 months later Davison LASA R)Hemi -) 4 Unchecked Died (1937) 8 months later O'Brien et al. ASA Quadri (+) (+) Vertical(N) Died (1945) PMDG* ‘on day 12 Brown et al. BA(?) L)Hemi (+) Unchecked Unchecked Static (1961) L)FP Meyer et al. ASA Quadri (+) (-) (D) Died (1962) RFP at 7th weak Fisher et al. R)VA UHemi (-) Unchecked Absent Died (1965) on day 25 Chokroverty Undefined L)Hemi (-) (-) Absent Died et al.(1975) L)FP 5 weaks later Leestma et al. Undefined R)Hemi (-) (-) Absent Improved (1976) R)FP. Ropper et al. R)VA(?) L)Hemi (-) (+) Horizontal(N) Improved (1979) L)FP Vertical(D) Mizutani et al ASA Quadri (+) (+) Upbeat(N) Died (1980) 8.5 months later Ho et al. Undefined R)Hemi (-) (-) Absent Improved (1981) R)FP Kase et al. ASA Quadri Unchecked (+) Upbeat(N) Died (1983) B)FP Bobbing on day 12 Paulson et al. ASA Quadri Unchecked (+) Unchecked Improved (1986) Sawada et al. Undefined L)Hemi (-) (+) Absent Improved (1990) Toyoda et al. ASA Quadri (+) (-) Horizontal(N) Static (1992) R)FP Ophthalmoplegia Present case Undefined Absent (-) (+) Upbeat(N) Improved (1994) (0) Abbreviations : BA=Basilar artery(or branches) ; ASA=Anterior spinal artery ; VA=Vertebral artery ; Quadri=Quadriparesis ; Hemi= Hemiparesis ; FP=Facial palsy ; R)=Right ; L)=Left ; B)=Both ; (N)=Nystagmus ; (D)=Diplopia ; PMDG=Poor maintenance of de- pression of gaze ; CGP=conjugate gaze palsy Medial medullary infarction upward and lateral gaze. Facial expression, sensation, and soft palate movement were symmetrical. Tongue deviation or atrophy was absent. Muscle tone was normal and strength was greater than MRC grade IV. Vibration sense was decreased on both sides and joint position sense was impaired on the right toe. Tendon reflexes were symmetrically increased, but Babinski reflex was flexor response. Bilateral dysmet- ria and clumsiness were observed on finger-to-nose test, heel-to-shin test, and rapid alternating move- ment. Romberg’s test was positive. Gait was impossi- ble due to severe truncal ataxia. The blood test showed increased levels of blood urea nitrogen, creatinine, and uric acid. Electrocardiography and echocardiography demonstrated no characteristic findings except LVH. Brain MRI revealed a well demarcated bilateral linear increased To-signals in the fostral medullary tegmentum (Fig. 1). In MR subtrac- tion angiography, basilar and vertebral arteries were competent, but both internal carotid arteries were tortuous, and the right middle cerebral artery was irregularly narrowed. Cortical potentials were absent bilaterally in the median nerve sensory evoked poten- tial (MNSEP) study. After admission, neurologic de- Fig. 1. T2-weighted magnetic resonance imaging without gadolinium-DTPA enhancement (done at 5 day from onset). On sagittal section of the rostral medulla, bilateral linear high signal intensity lesion is present in the tegmentum (black arrow). 195 ficits did not progress any more. And within two weeks, he was able to stand and walk with the conservative treatment. DISCUSSION Clinical manifestations of medial medullary infarction can be summarized into three categories (Table 2). Hemiparesis or quadriparesis was present unexcep- tionally. Tongue weakness was observed in about half (6/13), and most of them (5/6) in ASA syndrome. Typical alternating hemiparesis with ipsilateral hypog- lossal palsy and contralateral limb weakness was rare (1/13). Mild facial weakness was also common (9/ 15) and this was relatively frequent in VBA syndrome. In our case, motor weakness of the limbs, tongue, or face was not observed, which means that the cortico- bulbar and corticospinal tracts were not seriously affected. Ataxia shown in our patient was presumed Table 2. Symptoms and signs in medial medullary infarction (analysis of 15 reported cases) Symptoms and Signs Number of Frequency(%) ee eee ee Motor Weakness 15/15 100 Limb 15/15 100 Hemiparesis 9/15 60 Quadriparesis 6/15 40 Tongue 6/13* 46 Face 9/15 60 Proprioceptive Dysfunction 8/13** 62 Loss of vibration or position sense 8/13 62 Sensory ataxia 0/13 fe) Oculomotor disturbance Wate 58 Upbeat nystagmus 4/12 33 Horizontal nystagmus 3/12 25 Ocular bobbing 1/12 8 Gaze paresis 2/12 Fs (upward or lateral) Poor maintenance of 1/12 8 depression of gaze Diplopia_ Safle) 7 * No description or comment about tongue weakness in other 2 cases. ** No description or comment about sensory examination in other 2 cases. *** No description or comment about oculomotor findings in other 3 cases. 196 to be sensory type because it was definitely aggre- vated by eye closure, and position sense was severe- ly impaired. The main cause was supposed to be involvement of bilateral medial lemniscus. Findings of MNSEP which may assess the electrophysiological integrity of the medial lemniscus (Sawada et al., 1990) were compatible with the anatomical location of le- sions in MRI. Although the loss of vibration or position sense was common in medial medullary infarction (8/ 13), moderate to severe limb weakness was always combined, therefore an exact evaluation of limb ataxia or Romberg’s test might be difficult. Our patient was an exeception because his motor power was suffi- cient for such tests even during the early stage of the disease. According to the literature (Table 1), occlu- sion of ASA was detected in eight out of eleven cases with defined vascular territories, and perforating branches of VBA in three cases (Brown and Fang, 1961 ; Fisher and Curry, 1965; Ropper et al. 1979). But we think that the four undefined cases might be ascribed to the occlusion of penetrating branches rather than ASA. It is our suggestion to reclassify the medial medullary syndrome as “classical” ASA syn- drome and VBA syndrome. In our case, no potential source of cardiac or large arterial embolism could be found. But the history of hypertension, and the loca- tion and topography of infarction are highly suggestive of a small-vessel disease. The prognosis of medial medullary infarction is usually known to be poor, especially in the infarction of ASA territory which often result in respiratory distress and severe motor weak- ness. However, the prognosis was variable according to our review. Extensive infarction of ASA territory due to embolism resulted in a graver outcome, while small deeply located lesions ascribed to small-vessel dis- ease showed only minor neurologic deficits and more favorable outcome as in our case. In conclusion, we suggest that VBA syndrome due to small-vessel disease will probably result in better prognosis than the embolic ASA syndrome, which can be differenti- ated by its clinical features and MRI findings. J. -K. Roh, Y. -S. Lee REFERENCES Brown WJ, Fang HCH. Spastic hemiplegia in man- Lack of flaccidity in lesion of pyramidal tract. Neurology 1961 ; 11 : 829-36. Caplan LR. Bilateral distal vertebral artery occlusion. Neurolo- gy 1983; 33: 552-8. Chokroverty S, Rubino FA, Haller C. Pure motor hemiplegia due to pyramidal infarction. Arch Neurol 1975; 32: 647-8. Davison C. Syndrome of the anterior spinal artery of the medulla oblongata. Arch Neurol Psychiat. 1937; 37: 91-107. Davison C. Syndrome of the anterior spinal artery of the medulla oblongata. J Neuropathol Exp 1944 ; 3: 73-80. Fisher CM, Curry HB. Pure motor hemiplegia of vascular ongin. Arch Neurol 1965; 13 : 30-4. Ho KL, Meyer KR. The medial medullary syndrome. Arch Neurol 1981 ; 38 : 385-7. Kase CS, Varakis JN, Stafford JR, Mohr JP. Medial medullary infarction from fibrocartilaginous embolim to the anterior spinal artery. Stroke 1983; 14: 413-8. Leestma JE, Noronha A. Pure motor hemiplegia, medullary pyramid lesion, and olivary hypertrophy. J Neurol Neurosurg Psychiatry 1976 ; 39 : 877-84. Meyer JS, Hemdon RM. Bilateral infarction of the pyramidal tracts in man. Neurology 1962; 12 : 637-42. Mizutani T, Lewis RA, Gonatas NK. Medial medullary syn- drome in a drug abuser. Arch Neurol 1980 ; 37 : 425-8. O'Brien FB, Bender MB. Localizing value of vertical nystag- mus. Arch Neurol Psychiat 1945; 54 : 378-80. Paulson GW, Yates AJ, Paltan-Oritz JD. Does infarction of the medullary pyramid lead to spasticity? Arch Neurol 1986 ; 43: 93-5. Ropper AH, Fisher CM, Kleinman GM. Pyramidal infarction in the medulla- A cause of pure motor hemiplegia sparing the face. Neurology 1979; 29: 91-5. Sawada H, Seriu N, Udaka F, Kameyama M. Magnetic resonance imaging of the medial medullary infarction. Stroke 1990; 21 : 963-6. Toyoda K, Hasegawa Y, Yonehara T, Oita J, Ymaguchi T. Bilateral medial medullary infarction with oculomotor disorders. Stroke 1992; 23: 1657-9.