OBJECTIVE: To study the association of motor nerve conduction block (CB) with different subtypes of childhood Guillain-Barré syndrome (GBS). METHODS: A retrospective analysis was performed on the clinical and nerve electrophysiological data of 50 children with GBS. According to the results of nerve electrophysiology, the children were divided into an acute inflammatory demyelinating polyneuropathy (AIDP) group with 29 children and an acute motor axonal neuropathy (AMAN) group with 21 children. According to the presence or absence of motor nerve CB, the children with AMAN or AIDP were further divided into subgroups: group AMAN with or without motor nerve CB (n=10 and 11 respectively) and group AIDP with or without motor nerve CB group (n=19 and 10 respectively). The subgroups were compared in terms of age of onset, sex, Hughes Functional Grading Scale (HFGS) at nadir for the most severe involvement of motor function, and short-term prognosis based on HFGS score at 1 month after disease onset. RESULTS: Motor nerve CB was reversible in children with AMAN. AMAN children with motor nerve CB had a significantly lower HFGS score than those without motor nerve CB at 1 month after onset (P<0.05). AIDP children with motor nerve CB had a significantly higher HFGS score than those with motor nerve CB at 1 month after onset (P<0.05). CONCLUSIONS AMAN with reversible motor nerve CB suggests mild nerve fiber lesion and has better recovery than AMAN and AIDP without motor nerve CB in short term.
Child ; Guillain-Barre Syndrome ; Humans ; Neural Conduction ; Prognosis ; Retrospective Studies

BACKGROUND: Multifocal motor neuropathy (MMN), Lewis-Sumner syndrome (LSS), and many chronic inflammatory demyelinating polyradiculoneuropathies (CIDPs) are representative of acquired multifocal polyneuropathy and are characterized by conduction block (CB). This retrospective study aimed to investigate the demyelinating distribution and the selective vulnerability of MMN, LSS, and CIDP with CB (CIDP-CB) in nerves. METHODS: Fifteen LSS subjects (107 nerves), 24 MMN subjects (176 nerves), and 17 CIDP-CB subjects (110 nerves) were included. Their clinical information was recorded, blood and cerebrospinal fluid tests were conducted, and nerve conductions of the median, ulnar, radial, peroneal, and tibial nerves were evaluated. CB, temporal dispersion, distal motor latency (DML), and F-wave latency were recorded, and nerve conduction velocity, terminal latency index, and modified F-wave ratio were calculated. RESULTS: CB was more likely to occur around the elbow in CIDP-CB than in MMN (78.6% vs. 6.8%, P < 0.01) but less likely to occur between the wrist and the elbow than in LSS (10.7% vs. 39.3%, P < 0.05). Tibial nerve CB was most frequently observed in MMN (47.4%, P < 0.05). CIDP-CB was characterized by a prolonged DML in all nerves, and slow motor nerve velocity of the upper limb was significant when CB nerves were excluded (P < 0.05). CONCLUSIONS We report the different distributions of segmental and diffuse demyelination of the ulnar and tibial nerves in LSS, MMN, and CIDP-CB. These distinct distributions could help in differentiating among these conditions.
Humans ; Neural Conduction ; Peripheral Nerves ; Polyneuropathies ; Polyradiculoneuropathy, Chronic Inflammatory Demyelinating ; Retrospective Studies

Charcot-Marie Tooth disease type 1A (CMT1A), the major type of CMT, is caused by duplication of peripheral myelin protein 22 (PMP22) gene whose overexpression causes structural and functional abnormalities in myelination. We investigated whether miRNA-mediated regulation of PMP22 expression could reduce the expression level of PMP22, thereby alleviating the demyelinating neuropathic phenotype of CMT1A. We found that several miRNAs were down-regulated in C22 mouse, a CMT1A mouse model. Among them, miR-381 could target 3′ untranslated region (3′UTR) of PMP22 in vitro based on Western botting and quantitative Real Time-PCR (qRT-PCR) results. In vivo efficacy of miR-381 was assessed by administration of LV-miR-381, an miR-381 expressing lentiviral vector, into the sciatic nerve of C22 mice by a single injection at postnatal day 6 (p6). Administration of LV-miR-381 reduced expression level of PMP22 along with elevated level of miR-381 in the sciatic nerve. Rotarod performance analysis revealed that locomotor coordination of LV-miR-381 administered C22 mice was significantly enhanced from 8 weeks post administration. Electrophysiologically, increased motor nerve conduction velocity was observed in treated mice. Histologically, toluidine blue staining and electron microscopy revealed that structural abnormalities of myelination were improved in sciatic nerves of LV-miR-381 treated mice. Therefore, delivery of miR-381 ameliorated the phenotype of peripheral neuropathy in CMT1A mouse model by down-regulating PMP22 expression. These data suggest that miRNA can be used as a potent therapeutic strategy to control diseases with copy number variations such as CMT1A.
Animals ; Demyelinating Diseases ; In Vitro Techniques ; Mice ; MicroRNAs ; Microscopy, Electron ; Myelin Sheath ; Neural Conduction ; Peripheral Nervous System Diseases ; Phenotype ; Sciatic Nerve ; Tolonium Chloride ; Tooth Diseases ; Untranslated Regions

A 15-year-old male patient presented with a slow progression of painless right shoulder weakness over the previous six weeks. The magnetic resonance imaging revealed right C4–5 foraminal stenosis caused by right foraminal disc protrusion. The needle electromyography and nerve conduction studies revealed acute C5 and/or C6 radiculopathy. Instead of the initial surgical management modalities, we performed a cervical epidural steroid injection at the C4–5 level. From the day after the patient received the cervical epidural steroid injection, his right shoulder motor weakness improved progressively. Two weeks after the procedure, his right shoulder motor function had fully recovered.
Adolescent ; Constriction, Pathologic ; Electromyography ; Humans ; Magnetic Resonance Imaging ; Male ; Needles ; Neural Conduction ; Radiculopathy ; Shoulder

Dermatomyositis (DM) and polymyositis (PM) are representative idiopathic inflammatory myopathies characterized by symmetric and progressive proximal muscle weakness. Especially, DM is identified by characteristic skin lesions and has many extramuscular manifestations including various cardiac abnormalities, interstitial lung disease, and malignancy. However, involvement of peripheral nervous system in DM/PM is very rare and less known. The term “Neuromyositis” was introduced by Senator in 1893 to describe the concomitant involvement of the peripheral nervous system in DM/PM. Since then, a very few cases of neuromyositis have been reported mainly in the United States and Europe. Therefore, the pathogenetic mechanism and disease progression are unclear. In recent years, a few more cases were reported in Asia, specifically, China and Japan; however, none in Korea. Here, we describe a case of DM-associated neuromyositis in a 42-year-old man in Korea and review previous publications through literature research.
Adult ; Asia ; China ; Dermatomyositis ; Disease Progression ; Electromyography ; Europe ; Humans ; Japan ; Korea ; Lung Diseases, Interstitial ; Muscle Weakness ; Myositis ; Neural Conduction ; Peripheral Nervous System ; Peripheral Nervous System Diseases ; Polymyositis ; Skin ; United States

OBJECTIVE: To determine anatomical variation of the sural nerve (SN) by ultrasonography (US) and compare sensory nerve action potential (SNAP) of the SN obtained by a control method to that obtained with adjusted method using US. METHODS: Eighty legs of 40 healthy volunteers were enrolled. The location and formation of SN were investigated through US. Two methods of nerve conduction study (NCS) were then performed. In the control method, the cathode was placed 14 cm proximal to the lateral malleolus and the greatest SNAP amplitude was obtained by moving the cathode medially or laterally from just lateral to the calf-mid line. In adjusted NCS, the exact SN union site was stimulated in type 1. In other SN types, the stimulation was done directly over the nerve and the distance from the lateral malleolus was set to be 14 cm. RESULTS: It was found that 73.8% of the SNs were type 1, 22.5% were direct continuation of MSCN (type 2), and 3.8% were MSCN and LSCN without communicating (type 4). However, type 3 was not found. The union point in type 1 SN was 12.6±2.5 cm proximal to the lateral malleolus and 1.4±0.7 cm lateral to the calf-midline. After stimulation adjustment, SNAP amplitude in type 1 SN was significantly increased (20.7±5.5 μV vs. 27.1±6.7 μV). CONCLUSION: Anatomical variation of SN and its location were verified by US. US provides additional information for conducting sural NCS and helps obtain more accurate results.
Action Potentials ; Electrodes ; Healthy Volunteers ; Leg ; Methods ; Neural Conduction ; Sural Nerve ; Ultrasonography

Anatomic variation of palmar digital nerve pathways were reported in several cases. Selective exploration of palmar digital nerves with a nerve conduction study has been challenging, because of technical issues. We report a patient who received bilateral carpal tunnel release operation, complaining of a tingling sensation, and hypoesthesia on the middle and ring fingers. An electrodiagnostic study revealed a sensory neuropathy of palmar digital nerve of the left median nerve, supplying the ulnar side of the middle finger, and radial side of the ring finger. She underwent re-operation of open left carpal tunnel release, and a branching site of common digital nerves of the median nerve was identified not at the palm, but at a far proximal site around the distal wrist crease. Usefulness of an orthodromic sensory conduction study was clarified to eliminate volume conducted response or co-activation of nearby nerves in the patient with selective involvement of palmar digital nerve.
Anatomic Variation ; Carpal Tunnel Syndrome ; Electrodiagnosis ; Fingers ; Humans ; Hypesthesia ; Median Nerve ; Median Neuropathy ; Neural Conduction ; Sensation ; Wrist

Piriformis syndrome caused by an accessory belly of the piriformis muscle is very rare. Only a few cases have been reported. Here, we report a case of piriformis syndrome resulting from an extremely rare type of accessory belly of the piriformis muscle originated at the proximal third portion of the main piriformis muscle and attached separately to the greater trochanter inferior to the insertion of the main piriformis muscle. A definitive diagnosis of piriformis syndrome was made based on magnetic resonance imaging and magnetic resonance neurography findings that were consistent with results of nerve conduction study and needle electromyography.
Diagnosis ; Electromyography ; Femur ; Magnetic Resonance Imaging ; Needles ; Neural Conduction ; Piriformis Muscle Syndrome

Electrodiagnostic tests (EDX) is essential for the diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP). EDX could provide information about demyelinating pathology in the peripheral nerves. According to phenotypes, CIDP could be classified several phenotypes, which has different clinical manifestations, EDX could present a different distribution pattern of demyelinating lesions. In addition, EDX could be useful markers for predicting treatment response of prognosis of CIDP.
Classification ; Diagnosis ; Electrodiagnosis ; Neural Conduction ; Pathology ; Peripheral Nerves ; Phenotype ; Polyneuropathies ; Polyradiculoneuropathy, Chronic Inflammatory Demyelinating ; Prognosis

Guillain-Barré syndrome (GBS) is nowadays consider as an umbrella term that has heterogenous presentation depend on their subtypes. GBS is clinical diagnosis and its diagnosis can be supported by laboratory findings from cerebral spinal fluid study, nerve conduction study, anti-ganglioside antibodies, spinal magnetic resonance imaging and nerve ultrasound. Understanding atypical subtypes and GBS mimicking diseases are crucial for correct diagnosis. Both proper medical care for respiratory and autonomic dysfunction and immunotherapy are essential to improve outcome of GBS. Here, we summarized the current concept on diagnosis, immunopathophysiology and treatment of GBS.
Antibodies ; Diagnosis ; Guillain-Barre Syndrome ; Immunotherapy ; Magnetic Resonance Imaging ; Neural Conduction ; Ultrasonography