BACKGROUND AND PURPOSE: This retrospective cross-sectional study included 18 patients from unrelated families harboring mutations of the transthyretin gene (TTR), and analyzed their characteristics and geographical distribution in South Korea. METHODS: The included patients had a diagnosis of systemic amyloidosis, clinical symptoms, such as amyloid neuropathy or cardiomyopathy, and confirmation of a TTR gene mutation using genetic analysis recorded between April 1995 and November 2014. RESULTS: The mean age at disease onset was 49.6 years, and the mean disease duration from symptom onset to diagnosis was 3.67 years. Fifteen of the 18 patients were classified as mixed phenotype, 2 as the neurological phenotype, and only 1 patient as the cardiac phenotype. The most-common mutation pattern in South Korea was Asp38Ala, which was detected in eight patients. Thirteen patients reported their family hometowns, and five of the eight harboring the Asp38Ala mutation were from the Gyeongsang province in southeast Korea. The other eight patients exhibited a widespread geographical distribution. A particularly noteworthy finding was that the valine at position 30 (Val30Met) mutation, which was previously reported as the most-common TTR mutation worldwide and also the most common in the Japanese population, was not detected in the present South Korean patients. CONCLUSIONS: South Korean patients with hereditary TTR amyloidosis exhibited heterogeneous TTR genotypes and clinical phenotypes. The findings of this study suggest that the distribution of TTR amyloidosis in South Korea is due to de novo mutations and/or related to the other countries in East Asia.
Amyloid Neuropathies ; Amyloidosis* ; Asian Continental Ancestry Group ; Cardiomyopathies ; Cross-Sectional Studies ; Diagnosis ; Far East ; Genotype ; Humans ; Korea ; Phenotype ; Prealbumin* ; Retrospective Studies ; Valine

BACKGROUND AND PURPOSE: Responses to repetitive nerve stimulation (RNS) in patients with muscle-specific tyrosine kinase (MuSK) antibody (Ab)-positive myasthenia gravis (MG) vary depending on the muscles tested. We analyzed the RNS responses of limb and facial muscles in MuSK-Ab-positive and acetylcholine receptor (AChR)-Ab-negative MG (MuSK MG) and MuSK-Ab-negative and AChR-Ab-negative [double-seronegative (DSN)] MG patients. METHODS: We retrospectively compared RNS responses between 45 MuSK MG and 29 DSN MG. RNS was applied to the abductor digiti minimi, flexor carpi ulnaris, trapezius, orbicularis oculi, and nasalis muscles. RESULTS: Abnormal RNS responses in limb muscles were observed in 22.2 and 58.6% of MuSK MG and DSN MG patients, respectively, with abnormal facial responses observed in 77.8 and 65.5%, and abnormal responses observed in any of the five muscles in 86.7 and 72.4%. Abnormal RNS responses in the abductor digiti minimi or flexor carpi ulnaris were less frequent in MuSK MG (8.9 and 15.6%, respectively) than in DSN MG (37.9 and 55.2%), whereas the findings for other muscles were not significantly different between the groups. Abnormal facial responses but normal limb responses were independently associated with MuSK MG (odds ratio=5.224, 95% confidence interval=1.300–20.990). CONCLUSIONS: Abnormal RNS responses primarily in facial muscles without involvement of limb muscles were more pronounced in MuSK MG than in DSN MG. RNS of both facial and limb muscles in AChR-Ab-negative MG can increase the test sensitivity and aid in early suspicion of MuSK MG.
Acetylcholine ; Extremities ; Facial Muscles ; Humans ; Muscles ; Myasthenia Gravis* ; Protein-Tyrosine Kinases ; Retrospective Studies ; Superficial Back Muscles

Breast cancer is the second most common malignancy among Korean women. The 2002 National Cancer Center screening guideline breast cancer was revised via an evidence-based approach to provide medical personnel with a standard protocol of screening breast cancer. There is moderate-level evidence that biennial screening mammography in asymptomatic women aged 40 to 69 reduces breast cancer mortality, while low-level evidence suggests that screening mammography in women 70 years or older does not reduce breast cancer mortality. The committee concluded that the current evidence is insufficient to assess the benefits and harms of either ultrasonography or clinical breast examination as screening modalities for breast cancer. Future researches about the benefits and harms of the National Breast Cancer Screening Program in Korea are strongly required because the characteristics of breast cancer in Korea are different from those in the West, especially regarding dense breast. In conclusion, the committee recommends biennial screening mammography in asymptomatic women aged 40 to 69 years (grade B recommendation). The committee recommends selective screening mammography in women 70 years or older according to individual risk and preference (grade C recommendation). The committee neither recommends nor opposes ultrasonography and clinical breast examination as screening modalities (grade I recommendation). Symptomatic and high-risk women, however, should be offered complementary measures including ultrasonography and clinical breast examination under clinical supervision.
Breast ; Breast Neoplasms* ; Female ; Humans ; Korea ; Mammography ; Mass Screening* ; Mortality ; Organization and Administration ; Ultrasonography

BACKGROUND AND PURPOSE: X-linked bulbospinal muscular atrophy (X-BSMA) is characterized by bulbar and spinal muscular weakness and fasciculations. Although X-BSMA is a motor neuronopathy, there are several reports of myasthenic symptoms or decremental responses to repetitive nerve stimulation (RNS). We report the results of applying the RNS test to 15 patients among 41 with genetically confirmed X-BSMA; these 15 patients complained of fatigue, ease of becoming tired, or early muscular exhaustion. METHODS: The 3-Hz RNS test was performed on the trapezius, nasalis, orbicularis oculi, flexor carpi ulnaris, and abductor digiti quinti muscles. A decrement greater than 10% was considered abnormal. Additionally, a pharmacologic response to neostigmine was identified in three patients. RESULTS: A significant decrement was observed in 67% of patients, and was most common in the trapezius muscle (nine cases). The decrement of the trapezius muscle response ranged from 15.9% to 36.9%. The decrement was inversely correlated with the amplitude of compound muscle action potentials at rest. Neostigmine injection markedly improved the decrement in three patients, who showed noticeable decremental responses to 3-Hz RNS. CONCLUSIONS: This study shows that myasthenic symptoms and abnormal decremental responses to low-rate RNS are common in X-BSMA.
Action Potentials ; Bulbo-Spinal Atrophy, X-Linked ; Fasciculation ; Fatigue ; Humans ; Motor Neuron Disease ; Muscle Weakness ; Muscles ; Muscular Atrophy ; Myasthenia Gravis ; Neostigmine ; Neuromuscular Junction

The publisher wishes to apologize for incorrectly displaying the author (Seok Beom Gwon) name. We correct his name from Seok Beom Gwon to Seok Beom Kwon.

PURPOSE: Subacute combined degeneration (SCD) involves progressive degeneration of the spinal cord, optic nerve, and peripheral nerves. Vitamin B12 (VB12) is a co-factor in myelin synthesis. Because each cell that constitutes the myelin component in the central nervous system and peripheral nervous system is different, it is improbable that these cells undergo simultaneous degeneration. However, the sequence of degeneration in SCD has not been established. MATERIALS AND METHODS: In this study, we analysed medical records and electrophysiological data of patients who showed neurological symptoms and whose serum VB12 levels were lower than 200 pg/mL. RESULTS: We enrolled 49 patients in this study. Their mean VB12 level was 68.3 pg/mL. Somatosensory evoked potential (SEP) study showed abnormal findings in 38 patients. Of the 40 patients who underwent visual evoked potential (VEP) study, 14 showed abnormal responses. Eighteen patients showed abnormal findings on a nerve conduction study (NCS). In this study, abnormal posterior tibial nerve SEPs only were seen in 16 patients, median nerve SEPs only were seen in 3 patients, abnormal VEPs only in two, and abnormal NCS responses in one patient. No patient complained of cognitive symptoms. CONCLUSION: In SCD, degeneration appears to progress in the following order: lower spinal cord, cervical spinal cord, peripheral nerve/optic nerve, and finally, the brain.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Evoked Potentials, Somatosensory/physiology ; Female ; Humans ; Male ; Middle Aged ; Subacute Combined Degeneration/*blood/metabolism/*physiopathology ; Vitamin B 12/blood ; Vitamin B 12 Deficiency/blood/complications ; Young Adult

BACKGROUND AND PURPOSE: Charcot-Marie-Tooth disease (CMT) type 1A (CMT1A) is the demyelinating form of CMT that is significantly associated with PMP22 duplication. Some studies have found that the disease-related disabilities of these patients are correlated with their compound muscle action potentials (CMAPs), while others have suggested that they are related to the nerve conduction velocities. In the present study, we investigated the correlations between the disease-related disabilities and the electrophysiological values in a large cohort of Korean CMT1A patients. METHODS: We analyzed 167 CMT1A patients of Korean origin with PMP22 duplication using clinical and electrophysiological assessments, including the CMT neuropathy score and the functional disability scale. RESULTS: Clinical motor disabilities were significantly correlated with the CMAPs but not the motor nerve conduction velocities (MNCVs). Moreover, the observed sensory impairments matched the corresponding reductions in the sensory nerve action potentials (SNAPs) but not with slowing of the sensory nerve conduction velocities (SNCVs). In addition, CMAPs were strongly correlated with the disease duration but not with the age at onset. The terminal latency index did not differ between CMT1A patients and healthy controls. CONCLUSIONS: In CMT1A patients, disease-related disabilities such as muscle wasting and sensory impairment were strongly correlated with CMAPs and SNAPs but not with the MNCVs or SNCVs. Therefore, we suggest that the clinical disabilities of CMT patients are determined by the extent of axonal dysfunction.
Action Potentials ; Axons ; Charcot-Marie-Tooth Disease ; Cohort Studies ; Humans ; Muscles ; Neural Conduction

Dysferlinopathy is caused by mutations in the DYSF gene. To characterize the clinical spectrum, we investigated the characteristics of 31 Korean dysferlinopathy patients confirmed by immunohistochemistry. The mean age of symptom onset was 22.23 +/- 7.34 yr. The serum creatine kinase (CK) was highly increased (4- to 101-fold above normal). The pathological findings of muscle specimens showed nonspecific dystrophic features and frequent inflammatory cell infiltration. Muscle imaging studies showed fatty atrophic changes dominantly in the posterolateral muscles of the lower limb. The patients with dysferlinopathy were classified by initial muscle weakness: fifteen patients with Miyoshi myopathy phenotype (MM), thirteen patients with limb girdle muscular dystrophy 2B phenotype (LGMD2B), two patients with proximodistal phenotype, and one asymptomatic patient. There were no differences between LGMD2B and MM groups in terms of onset age, serum CK levels and pathological findings. Dysferlinopathy patients usually have young adult onset and high serum CK levels. However, heterogeneity of clinical presentations and pathologic findings upon routine staining makes it difficult to diagnose dysferlinopathy. These limitations make immunohistochemistry currently the most important method for the diagnosis of dysferlinopathy.
Adolescent ; Adult ; Age of Onset ; Creatine Kinase/blood ; Distal Myopathies/pathology ; Female ; Humans ; Immunohistochemistry ; Male ; Membrane Proteins/genetics ; Middle Aged ; Muscle Proteins/genetics ; Muscular Atrophy/pathology ; Muscular Dystrophies, Limb-Girdle/*diagnosis/genetics/pathology ; Mutation ; Phenotype ; Republic of Korea ; Tomography, X-Ray Computed ; Young Adult

BACKGROUND: Lambert-Eaton myasthenic syndrome (LEMS) is a presynaptic neuromuscular junction disorder that is most frequently associated with small-cell lung cancer (SCLC). The titers of antibodies against voltage-gated calcium channels are frequently increased in LEMS, but only rarely is titer of anti-acetylcholine-receptor-binding antibodies (AChR-abs) increased. CASE REPORT: A 57-year-old male was admitted to our hospital due to dry mouth and eyes and progressive proximal limb weakness of 2 months duration. The results of a repetitive nerve stimulation test disclosed all criteria for the electrophysiological LEMS pattern, and the patient's AChR-abs titer was 0.587 nmol/L. At a follow-up performed 5 years after successful treatment of SCLC and LEMS, his AChR-abs titer had decreased to 0.001 nmol/L. CONCLUSIONS: We suggest that this was a case of transient pseudopositivity of AChR-abs in SCLC with LEMS.
Antibodies ; Calcium Channels ; Extremities ; Eye ; Follow-Up Studies ; Humans ; Lambert-Eaton Myasthenic Syndrome ; Lung ; Lung Neoplasms ; Male ; Mouth ; Myasthenia Gravis ; Neuromuscular Junction Diseases

Acute sensorimotor polyneuropathy that resembles Guillain-Barre syndrome (GBS) is rarely accompanied with nephrotic syndrome, and its underlying immunological mechanisms are unclear. A 56-year-old man presented with simultaneous acute progressive symmetric sensorimotor polyneuropathy and proteinuria. A kidney biopsy revealed focal segmental glomerulosclerosis. Serial electrophysiologic studies showed only a transient proximal conduction block in the median nerve, stimulated somatosensory evoked potential and prolonged terminal latencies of the median and peroneal nerves. The patient's neurologic deficits and kidney dysfunction recovered with corticosteroid treatment. Our case showed that somatosensory evoked potential study can be an important objective tool in the diagnosis of acute polyneuropathy with normal distal nerve conduction and that corticosteroids should be considered in the initial treatment of GBS-resembling polyneuropathy associated with nephrotic syndrome.
Evoked Potentials, Somatosensory/physiology ; Humans ; Male ; Middle Aged ; Nephrotic Syndrome/*diagnosis/*physiopathology ; Polyneuropathies/*diagnosis/*physiopathology