Two Cases of Myasthenia Gravis Showing Fatigibility Presenting with Decreased Gain of Smooth Pursuit / 대한평형의학회지

Myasthenia gravis (MG) is an autoimmune disease caused by autoantibodies to the acetylcholine receptors of the neuromuscular junction characterized by weakness and abnormal fatigability of the muscles. Therefore, the diagnosis of MG depends on the recognition of this distinctive pattern of fatigable weakness. Previous studies presented the diagnostic efficacy of saccadic eye movements in patients with ocular MG. We here in report 2 patients of ocular MG showing the fatigue effects during repetitive sustained smooth pursuit, and the effects of the administration of edrophonium on myasthenic smooth pursuit. Changes in smooth pursuits reflecting peripheral and secondary central mechanisms were demonstrated.

Visuospatial Dysfunction in Patients With the Right Vestibular Neuritis / 대한평형의학회지

Acute vestibular neuritis (VN) is characterized by acute/subacute vertigo with spontaneous nystagmus and unilateral loss of semicircular canal function. Vestibular system in human is represented in the brain bilaterally with functional asymmetries of the right hemispheric dominance in the right handers. Spatial working memory entails the ability to keep spatial information active in working memory over a short period of time which is also known as the right hemispheric dominance. Three patients (patient 1, 32-year-old female; patient 2, 18-year-old male; patient 3, 63-year-old male) suffered from acute onset of severe vertigo, nausea and vomiting. Patients 1 and 2's examination revealed VN on the right side showing spontaneous left beating nystagmus and impaired vestibular ocular reflex on the right side in video head-impulse and caloric tests. Patient 3's finding was fit for VN on the left side. We also evaluated visuospatial memory function with the block design test in these 3 VN patients which discovered lower scores in patients 1 and 2 and the average level in patient 3 compare to those of healthy controls. Follow-up block design test after resolved symptoms showed within normal range in both patients. Our cases suggest that the patients with unilateral peripheral vestibulopathy may have an asymmetrical effect on the higher vestibular cognitive function. The right VN can be associated with transient visuospatial memory dysfunction. These findings add the evidence of significant right hemispheric dominance for vestibular and visuospatial structures in the right-handed subjects, and of predominant dysfunction in the hemisphere ipsilateral to the peripheral lesion side.

Focal Subarachnoid Hemorrhage Mimicking Recurrent Transient Ischemic Attack

Focal subarachnoid hemorrhage occasionally presents as transient focal neurologic episodes mimicking transient ischemic attack (TIA). Unless properly diagnosed, it may aggravate cerebral hemorrhage by administering antithrombotic agents. Therefore, clinicians need to be aware that such focal subarachnoid hemorrhage sometimes cannot be detected on noncontrast computed tomography and blood-sensitive magnetic resonance imaging can detect even a small amount of hemorrhage. We describe an 85-year-old woman with focal subarachnoid hemorrhage and possible cerebral amyloid angiopathy who presented transient left arm weakness recurrently, which mimicked TIA.

Epilepsy and Driving Regulation in Korea

In Korea, current status of epilepsy and driving are challenging and there are lack of formal legal guidelines about driving in patients with epilepsy. According to the default standards in Korean Road Traffic law, patients with epilepsy are restricted or prohibited from driving except who are conditionally allowed to drive by the Aptitude Judgement Committee (AJC). Though the AJC consist of medical doctors and traffic officials, new regulation and guidelines are required for various type of seizure and characteristics of patients with epilepsy. This review outlines the current applicable legislation about epilepsy and driving in Korea as well as that of the overseas country calling for new laws to establish a consistent assessment.

Superior Oblique Myokymia Associated with Neurovascular Cross Compression

Superior oblique myokymia (SOM) is a rare disorder characterized by unilateral paroxysmal oscillopsia or diplopia. Recent studies revealed that SOM can be associated with neuro-vascular cross compression (NVCC) of the trunk of the trochlear nerve. Although it frequently occurs without any underlying systemic disease or concurrent neurologic sign, we need to consider this NVCC especially in cases with persistent disturbing symptoms. Hereby, we present two cases of SOM whose neuroimaging studies suggest NVCCs and, discuss recent update of the pathomechanism of SOM.

Parasomnia as an Initial Presentation of Narcolepsy

Narcolepsy is characterized by excessive daytime sleepiness, cataplexy, sleep paralysis and hypnagogic hallucinations. Only a few studies have focused on non-rapid eye movement (NREM) and REM parasomnias in narcolepsy. We report a narcolepsy without cataplexy patient presenting parasomnia as an initial symptom. A 18-year-old boy was admitted to hospital for abnormal behavior of sitting up during sleep over 2 years. He had a symptom of lethargy without cataplexy and subjective excessive daytime sleepiness, but his family found him often asleep during daytime. He underwent 3 times of polysomnography (PSG) including 1 multiple sleep latency test (MSLT) after the last PSG. The last PSG showed 1 episode of abrupt sitting. Three sleep REM onset period was observed in MSLT which was not detect in PSG. Parasomnia as an initial symptom of narcolepsy is a rare clinical entity. The MSLT may be useful in the evaluation of patients with parasomnia and unexplained hypersomnia.

Clinical Significance of Perverted Head-Shaking Nystagmus / 대한평형의학회지

OBJECTIVES: We investigated clinical significance of head shaking nystagmus (HSN) and perverted HSN (pHSN) in patients with peripheral and central vestibular disorders. METHODS: We reviewed medical records of 822 consecutive subjects who were referred to a dizziness clinic. We performed neurologic examination including video-oculography in darkness for 60 seconds before, during and for 100 seconds after head-shaking. HSN was considered to develop when post-head-shaking nystagmus last at least 5 beats with latency from end of head-shaking of no more than 5 seconds, and a velocity at least 3°/sec. RESULTS: In control group (n=45), there were observed spontaneous nystagmus (SN) in 2.2%, HSN in 17.8%, pHSN in 6.7%. In patients with peripheral vestibular disorder group (n=397), there were observed SN in 14.1%, HSN in 40.6%, pHSN in 9.8%. In patients with central vestibular disorder group (n=217), there were observed SN in 17.5%, HSN in 24.0%, pHSN in 13.4%. In unspecified dizziness group (n=208), there were observed SN in 1.9%, HSN in 13.0%, pHSN in 1.9%. pHSN was frequently observed in central vestibular disorders such as stroke, vestibular migraine, cerebellar ataxia, and vertebro-basilar insufficiency. However, pHSN was also observed at higher rate than expected in peripheral vestibular disorders including benign paroxysmal positional vertigo especially involving vertical canals, Meniere disease and even in unilateral vestibulopathy. CONCLUSIONS: Our results show that perverted HSN in dizzy populations was frequently observed not only in cases of central vestibular disorders but also in peripheral disorders. Perverted HSN can develop by any conditions that cause difference in vestibular velocity storage in vertical component of vestibular-ocular reflex.

Brain Hypometabolism in Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome / 대한평형의학회지

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a slowing progressive ataxic disorder characterized by bilateral vestibulopathy, cerebellar ataxia and somatosensory impairment. Autonomic dysfunction is recently considered as a core feature in CANVAS in addition to these symptoms. In most cases, patients with CANVAS show cerebellar atrophy in brain imaging, but some cases show minimal or no atrophy of cerebellum. Brain (18F)-fluoro-2-deoxy-D-glucose positron emission tomography (¹⁸F-FDG PET) study can be a complimentary tool to diagnosis CANVAS in cases of no structural abnormality such as cerebellar atrophy. Hereby, we present a case of CANVAS with minimal atrophy of cerebellum but showing a prominent hypometabolism in cerebellum, thalamus and posterior cingulate cortex in ¹⁸F-FDG PET.

A Case of Partial Oculomotor Nerve Palsy Caused by Vascular Compression in Idiopathic Intracranial Hypertension / 대한평형의학회지

Pupil-involving oculomotor nerve palsy (ONP) is frequently associated with compressive lesion such as intracranial aneurysm originating from the posterior communicating arteries. Vascular variant of posterior intracranial circulation is regarded as an uncommon cause and association between these vascular variants and intracranial hypertension has not been reported. We present an 18-year-old girl with pupil-involving ONP combined with idiopathic intracranial hypertension who revealed compression of oculomotor nerve by a vascular variant of superior cerebellar artery (SCA). This is a rare case of an ONP attributed to compressive effect from an aberrant SCA affected by intracranial hypertension.

Four Cases of Wernicke's Encephalopathy with Impaired Horizontal Vestibular Ocular Reflexes / 대한평형의학회지

Wernicke's encephalopathy (WE) is a neurological disorder induced by a dietary vitamin B1 (thiamine) deficiency which is characterized by encephalopathy, gait ataxia, and variant ocular motor dysfunction. In addition to these classical signs of WE, a loss of the horizontal vestibulo-ocular reflex (VOR) is being reported as the major underdiagnosed symptoms in WE. In this retrospective single center study, we report four cases of WE initially presented with impaired horizontal VOR in addition to the classical clinical presentations, and imaging and neurotological laboratory findings were described.

Concurrence of Acute Cerebral Infarction and Peripheral Neuropathy Associated with Hypereosinophilic Syndrome

Hypereosinophilic syndrome is a rare disorder involving the eosin concentration being elevated to more than 1500/µL in the peripheral blood for 6 months, and it causes various complications in the heart, skin, and nervous and respiratory systems. The simultaneous occurrence of neurological complications of hypereosinophilic syndrome is rare. Here we report a patient with hypereosinophilic syndrome who suffered from acute cerebral infarction and peripheral neuropathy during the same period.

Hypoglycemic Cognitive Impairment Presenting as Anomic Aphasia

No abstract available.

Wernicke Encephalopathy Associated with Acute Wet Beriberi

Wernicke encephalopathy is usually accompanied with peripheral neuropathy, known as dry beriberi. In contrast, wet beriberi presenting as cardiovascular symptoms rarely occurs. The acute type of wet beriberi can be fatal, if untreated quickly. It is reported that the cerebellar vermis has a role of the coordination and control of cardiovascular and autonomic reflex activities. We report a 58-year-old man showing acute wet beriberi in Wernicke encephalopathy with cerebellar vermis lesion.

Secondary Intracranial Hypertension Due to Unusual Causes

Secondary intracranial hypertension (IH) is a syndrome with various etiologies, including a brain tumor, head trauma, hypoparathyroidism, hydrocephalus, meningitis, drug use, or venous obstruction. It is reasonably straightforward to diagnose secondary IH induced by these diseases. However, diagnosing secondary IH induced by unpredictable extracranial lesion is difficult, and is based largely on subtle neurological symptoms or signs and usually can be achieved by an extracranial evaluation. Here we describe four cases of secondary IH with unusual causes.

Intractable Vomiting as an Initial Manifestation of Neuromyelitis Optica

No abstract available.

Ocular Vestibular Evoked Myogenic Potentials Produced by Stimulation With Bone-conducted Vibration in Healthy Subjects / 대한평형의학회지

BACKGROUND AND OBJECTIVES: To provide the empirical basis for using ocular vestibular evoked myogenic potentials (oVEMPs) in response to bone-conducted vibration (BCV) stimulation to indicate vestibular function in normal subjects. MATERIALS AND METHODS: In response to bone-conducted tone burst (90 dB nHL and 100 dB nHL with frequencies 500 Hz and 1,000 Hz, the oVEMPs were measured in 45 healthy controls. The early negative component (n10) of the oVEMP to brief BCV of the forehead and at each mastoid process is recorded by surface electromyography electrodes just beneath the eyes. We used a hand-held vibrator (Bruel and Kjaer 4810 Mini-Shaker) placed on the forehead, in the midline at the hairline (Fz) and at each mastoid process and quantified the individual differences in n10 magnitude, latency and symmetry to Fz and mastoid BCV at each frequency. RESULTS: In normal subjects, n10 responses were symmetrical in the two eyes during Fz and both mastoid stimuli and the latencies of the onset were consistent among subjects. Response rate is similar between Fz and mastoid stimuli. However, at each stimulation site, response rate is higher on 500 Hz than on 1,000 Hz stimulation. During the mastoid stimuli, the onset latency is slightly shorter and amplitude is larger than the Fz stimuli. The average amplitudes decreased with age and average latency (to peak) increased slightly with increasing age. CONCLUSION: Clear oVEMP responses to bone-conducted Fz and mastoid stimuli were evoked from normal subjects. It is concluded that bone-conducted stimuli as well as air conduction can evoke myogenic potentials from the ocular muscles.

Isaacs' Syndrome Associated With Acetylcholine Receptor Antibodies Developed After Removal of Malignant Thymoma

Isaacs' syndrome is a rare and heterogeneous syndrome of continuous muscle fiber activity that originates from peripheral nerves. We report a 56-year-old male patient who showed symptoms of Isaacs' syndrome after the removal of a malignant thymoma. Needle electromyography revealed spontaneously occurring repetitive myokymic discharge in the affected muscles. Acetylcholine receptor (AChR) antibodies were significantly elevated, but clinical and electrophysiologic findings did not indicate the presence of myasthenia gravis. We deduce that in Isaacs' syndrome, raised AChR antibodies may facilitate rather than inhibit cholinergic action.

Metronidazole-induced Reversible Cerebellopathy / 대한평형의학회지

Metronidazole is a nitroimidazole antibiotic used for anaerobic infections, protozoan infections, and Helicobacter pylori infections. It may produce rare but well known neurological adverse effects including peripheral neuropathy, encephalopathy, cerebellar dysfunction, and seizures. We describe three patients with metronidazole-induced reversible cerebellar dysfunctions characterized by abnormal oculomotor findings, dysmetria, and ataxia. The diagnosis of metronidazole toxicity was made clinically and supported by the brain MRI findings. The neurological signs and abnormal signal intensity on MRI resolved after discontinuation of metronidazole.

Downbeat, Gaze-evoked and Perverted Head-shaking Nystagmus Associated with Dapsone Toxicity / 대한평형의학회지

Dapsone is an agent commonly used to treat leprosy and its most common adverse effect is a hemolytic anemia. We present a patient who showed transient downbeat, bilateral horizontal gaze-evoked nystagmus (GEN), and perverted head-shaking nystagmus after taking a large dose of dapsone. These oculomotor abnormalities are assumed to be a reversible vestibulocerebellar dysfunction caused by over-dose of dapsone.

Two Cases of Methyl Bromide Intoxication Mimicking Bickerstaff's Brainstem Encephalitis

BACKGROUND: Methyl bromide is toxic to the central and peripheral nervous systems. Two patients with occupational exposure to this agent are described. CASE: Two cases of previously healthy young men were involved. They had worked in a fumigating plant spraying fruits using methyl bromide for several months before admission. They showed general weakness, severe ataxia, bilateral dysmetria and bilateral lateral gaze limitation. And gaze-evoked nystagmus was observed in one of them. Brain MRI showed symmetrically increased signal intensity lesions including the brainstem, cerebellum and splenium of corpus callosum. After conservative treatment, they gradually improved over the next few weeks. CONCLUSIONS: Symmetry and topography of our patients??clinical and radiographic abnormalities support the proposal that methyl bromide exposure can produce symptoms similar to Bickerstaff's brainstem encephalitis.