Dayoung Kim

Background: Mild cognitive impairment (MCI) is clinically heterogeneous, yet most prognostic studies rely on binary conversion endpoints or expensive biomarkers unavailable in routine practice. Objective: To identify trajectory classes of the Clinical Dementia Rating-Sum of Boxes (CDR-SB) progression in MCI using latent class growth analysis (LCGA) and to determine whether they capture clinically relevant variation not reducible to Mini-Mental State Examination (MMSE) trajectories. Methods: LCGA was applied to longitudinal CDR-SB data from 121 MCI patients (baseline global CDR = 0.5) with two or more serial assessments across up to eight visits at three tertiary hospitals. Models with one through four classes were compared using BIC, AIC, entropy and minimum class size, with annual MMSE change and dementia conversion (global CDR ≥ 1) as external validators. Results: A four-class model was selected: Stable (n = 20, 16.5%; −0.08 per visit; 0% conversion), Slow (n = 46, 38.0%; +0.41 per visit; 47.8%), Moderate (n = 22, 18.2%; +0.75 per visit; 81.8%), and Fast (n = 33, 27.3%; +2.07 per visit; 100%); conversion-free survival differed across classes (log-rank p < 0.001). Two classes with near-identical MMSE decline differed markedly in CDR-SB slope and conversion. The stability of the Stable class persisted when all classes were restricted to their first two visits. Conclusions: In this tertiary-care cohort, serial CDR-SB trajectory classification identified clinically meaningful MCI subgroups, including functional heterogeneity invisible to MMSE monitoring alone; pending external validation it may offer practical, low-cost prognostic value where biomarkers are unavailable.

Rare diseases are predominantly genetic or inherited, and patients with these conditions frequently exhibit neurological symptoms. Diagnosing and treating many rare diseases is a complex challenge, and their low prevalence complicates the performance of research, which in turn hinders the advancement of therapeutic options. One strategy to address this issue is the creation of national or international registries for rare diseases, which can help researchers monitor and investigate their natural progression. In the Republic of Korea, we established a registry across 5 centers that focuses on 3 rare diseases, all of which are characterized by gait disturbances resulting from motor system dysfunction. The registry will collect clinical information and human bioresources from patients with amyotrophic lateral sclerosis, spinocerebellar ataxia, and hereditary spastic paraplegia. These resources will be stored at ICreaT and the National Biobank of Korea. Once the registry is complete, the data will be made publicly available for further research. Through this registry, our research team is dedicated to identifying genetic variants that are specific to Korean patients, uncovering biomarkers that show a strong correlation with clinical symptoms, and leveraging this information for early diagnosis and the development of treatments.

Background and Objectives: One of the most challenging tasks in a clinical setting is to differentiate between complex regional pain syndrome (CRPS) type II and traumatic neuropathic pain (NeP). CRPS is characterized by several dysautonomic manifestations, such as edema, hyper/hypohidrosis, skin color change, and tachycardia. This study compared the outcomes of autonomic function screening tests in patients with CRPS type II and traumatic NeP for diagnostic differentiation. Materials and Methods: CRPS type II was diagnosed according to the Budapest research criteria, while NeP was diagnosed according to the updated grading system suggested by the International Association for the Study of Pain Special Interest Group on Neuropathic Pain in 2016. Twenty patients with CRPS type II and twenty-five with traumatic NeP were investigated. Results: Twelve patients with CRPS type II presented abnormal results for the quantitative sudomotor axon reflex test (QSART). Abnormal QSART results were more common in the CRPS type II group. Conclusions: Analysis of QSART combined with other ancillary tests can help in the differential diagnosis of CRPS type II and traumatic NeP if factors influencing abnormal QSART are sufficiently controlled.

Jung S, et al. J Clin Neurol. 2023 Jul;19:e56. https://doi.org/10.3988/jcn.2023.0007

Congenital myasthenic syndromes (CMSs) are rare genetic disorders characterized by weakness and fatigue resulting from impaired neuromuscular transmission. Genetic testing can confirm the diagnosis for some types of CMS; however, variations in genotype, clinical phenotypes, age at disease onset, and responses to treatment make diagnosis very difficult. Here we present two adult patients who had significant decremental responses in repetitive nerve stimulation testing and multi-minicore pathology, and who responded to treatment with a cholinesterase inhibitor.