Digital Biomarkers for Alzheimer’s Disease

There is a growing interest in developing new biomarkers using digital devices. The primary purpose of digital biomarkers is to obtain features based on multi-dimensional data such as multiple data sources from various digital devices and time-series data reflecting temporal changes. Therefore, digital biomarkers can be used to measure the behavioral patterns of individuals in their daily lives in contrast to traditional biomarkers that reflect specific time points in clinical or laboratory settings. However, there are still several limitations including validation and interpretation. This article reviews the potential of digital biomarkers, explores previous studies on digital phenotypes related to Alzheimer’s disease, and discusses the future challenges of implementing digital biomarkers in the medical field.

Bilateral Thalamic Infarction Related to Artery of Percheron with Microembolic Signal

The artery of Percheron (AOP) is an uncommon variant of the posterior cerebral artery that supplies blood to the paramedian thalamus and rostral midbrain. AOP is often difficult to recognize with intracranial magnetic resonance angiography due to its small size. Although a number of case reports of AOP occlusion have been published, cause of the occlusion is mostly unclear. We experienced a case of AOP occlusion which resulted in bilateral thalamic infarction. It was most likely caused by a microembolism through right-left shunt.

A Comparison of Speech Features between Mild Cognitive Impairment and Healthy Aging Groups

Background@#and Purpose: Language dysfunction is a symptom common to patients with Alzheimer's disease (AD). Speech feature analysis may be a patient-friendly screening test for early-stage AD. We aimed to investigate the speech features of amnestic mild cognitive impairment (aMCI) compared to normal controls (NCs). @*Methods@#Spoken responses to test questions were recorded with a microphone placed 15 cm in front of each participant. Speech samples delivered in response to four spoken test prompts (free speech test, Mini-Mental State Examination [MMSE], picture description test, and sentence repetition test) were obtained from 98 patients with aMCI and 139 NCs.Each recording was transcribed, with speech features noted. The frequency of the ten speech features assessed was evaluated to compare speech abilities between the test groups. @*Results@#Among the ten speech features, the frequency of pauses (p=0.001) and mumbles (p=0.001) were significantly higher in patients with aMCI than in NCs. Moreover, MMSE score was found to negatively correlate with the frequency of pauses (r=−0.441, p<0.001) and mumbles (r=−0.341, p<0.001). @*Conclusions@#Frequent pauses and mumbles reflect cognitive decline in aMCI patients in episodic and semantic memory tests. Speech feature analysis may prove to be a speech-based biomarker for screening early-stage cognitive impairment.

Two Focal Seizure in a Patient Caused by Different Mechanism

Poststroke epilepsy is the most common cause of epilepsy in adult. Acute symptomatic seizure is a provoked seizure usually caused by systemic metabolic disorders. If stroke patient has a seizure, it is very important to discriminate whether it is a poststroke epilepsy or provoked seizure. The reason is that there are differences in the approach to treatment and the continuation of antiepileptic drugs. We report a stroke mimic patient who had two different mechanisms of focal seizures.

Neurovascular Compression Confirmed by 3D T2-Weighted Volume Isotropic Turbo Spin-Echo Acquisition Sequence in Trigeminal Neuralgia

No abstract available.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Hypoglycemic Cognitive Impairment Presenting as Anomic Aphasia

No abstract available.

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.

Fregoli Syndrome Due to Right Hippocampal Vasculitis in Neuro-Behcet's Disease

We report a 40-year-old man with known neuro-Behcet's disease who showed Fregoli syndrome after a seizure attack. A patient with Fregoli syndrome strongly believes that the psychological identity of a familiar person remains unchanged while at the same time there is a marked change in physical identity. The anatomical basis of Fregoli syndrome is still unclear; our patient showed right hippocampal vasculitis in MRI and frontal dysfunction in neuropsychological testing.

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.

Diagnosis of Acute Cerebral Fat Embolism by Diffusion-Weighted Image in Patient With Multiple Fractures

No abstract available.