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HOME > J Korean Bal Soc > Volume 4(1); 2005 > Article
Original Article Periodic Alternating Nystagmus in Focal Cerebellar Lesion

DOI: https://doi.org/
Department of Neurology, College of Medicine, Seoul National University‘ Department of Neurology, College of Medicine, Dong-a University*
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A 44-year-old previously healthy man developed dull-nature headache in occipital area two months before admission. The headache became worse and associated with nausea and vomiting. He visited a local hospital and was diagnosed as brain mass on MRI, causing him to seek further medical advice. He was transferred to our hospital and underwent the midline suboccipital craniectomy for removal of the mass with suggestion of 4th ventricle pendymoma. After the operation, the patient started to complain of persistent osillopia. On examination, visual acuity was normal and bilateral pupils were symmetric and normally reactive to light. He had a full range of extraocular movements. A spontaneous horizontal jerk nystagmus, whose amplitude was increased by gaze toward the side of quick phases of nystagmus. The direction was reversed by gaze toward the side of slow phases of nystagmus. The horizontal nystagmus continuously reversed its direction every 1 to 2 minutes, with a brief transition period. He showed left central type facial palsy and left hemiparesis. Pain and temperature senses were reduced in the left arm and leg. Deep tendon reflexed were increased and the Babinski sign was positive in the left side. Oculographic study In light, periodic alternating nystagmus (PAN) was observed. An approximately 140-second left beating nystagmus; approximately 8-second pause; and an approximately 70-second right beating nystagmus were recorded. The amplitude was larger in the left-side nystagmus (maximum SPV: 17°/s) than in the right-side nystagmus (maximum SPV: 7°/s). In darkness, the cycle and amplitude of the nystagmus was not changed. PAN was not affected by vibratory stimulations, head-shaking test and positioning test including lying down, straight head hanging and Dix-Hallpike test. Remarkably, the amplitude of PAN increased on head tilt on sitting position or head turning on supine position to the side of quick phases of nystagmus, whereas decreased to the side of slow phases of nystagmus. Follow-up MRI after operation showed high intensity lesion in the left dorsal medulla and nodulus with complete removal of previous mass in 4th ventricle. PAN was markedly improved taking baclofen 40mg a day.


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