Paramyotonia congenita (PMC) is characterized by nondystrophic myotonia aggravated by exercise and cold exposure. SCN4A mutations manifest as various phenotypes of channelopathy, including PMC, myotonia congenita, and periodic paralysis. SCN4A-related channelopathy is characterized by autosomal dominant inheritance. Parental gonadal mosaicism is suspected in cases of recurrent de novo mutation in an autosomal dominantly inherited disease. We report a case of two Korean brothers presenting with PMC due to same de novo SCN4A point mutation, probably due to parental gonadal mosaicism.

Tram-track and doughnut-shaped enhancements of the optic nerve sheath in axial and coronal magnetic resonance imaging (MRI) views, respectively, play crucial roles in the diagnosis of optic nerve sheath meningioma (ONSM). However, this finding is not specific to ONSM since it can also be observed in optic perineuritis (OPN). Here we report a 42-year-old female with ONSM who presented with clinical and MRI findings similar to those of OPN.

Citations

• Freiburg Neuropathology Case Conference: Progressive Optic Nerve Lesion Over a 16-Year Period
  I. E. Duman Kavus, R. Sankowski, R. Rölz, A. Dressing, M. Prinz, H. Urbach, D. Erny, C. A. Taschner
  Clinical Neuroradiology.2025; 35(1): 215.     CrossRef

Some cases of myasthenia gravis (MG) with abnormal spontaneous activity (ASA) in needle electromyography (EMG) have been reported, but the associated clinical characteristics remain to be fully elucidated. We report the case of a 36-year-old male with MG in whom ASA was observed. This study highlights that ASA may appear in needle EMG in patients with severe MG who predominantly have bulbar and/or respiratory involvement. Care is needed because this often accompanies myopathic features and can be misdiagnosed as myopathy.

Evoked potentials (EPs) measures the electrophysiologic responses of the nervous system to variety of stimuli. In clinical practice, only a few are used on a routine basis. Because of the small amplitude of EPs recorded by noninvasive methods, computer summation or averaging generally is necessary to resolve them from background noise. Therefore, waveform acquisition under good condition according to standard method is important. We aimed to provide the standards for clinical EP equipment, technical consideration and minimal requirements for obtaining good clinical EP waveforms, and general criteria for writing EP reports in practice as Korean guidelines.

Citations

• Prolonged Visual Evoked Potential Latencies in Dogs Naturally Infected with Canine Distemper Virus
  Mary Gutiérrez, Luis Delucchi, Alejandro Bielli, José Manuel Verdes
  Viruses.2024; 16(11): 1721.     CrossRef
• Prognostic value of brainstem auditory and visual evoked potentials in cardiac arrest patients with targeted temperature management
  Jee Yong Lim, Sang Hoon Oh, Kyu Nam Park, Seung Pill Choi, Joo Suk Oh, Chun Song Youn, Han Joon Kim, Hyo Joon Kim, Hwan Song
  Resuscitation.2021; 164: 12.     CrossRef
• Abnormality of multimodal evoked potentials in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
  Edyta Dziadkowiak, Maria Ejma, Malgorzata Wieczorek, Pawel Pec, Krzysztof Slotwiński, Slawomir Budrewicz, Anna Zimny, Magdalena Koszewicz
  Neurological Sciences.2020; 41(9): 2495.     CrossRef

Visual evoked potentials (VEPs) are frequently used to assess the anterior and posterior visual pathways. In particular, the use of VEPs have been increasing in various fields such as evaluation of the optic nerves in patients with multiple sclerosis. The performance of VEP test can be affected by various factors such as stimulus type and subject condition, and its interpretation is also difficult. However, there have been no guidelines for performing and interpreting VEPs in Korea. Therefore, we aimed to provide comprehensive information regarding basic requirement and interpretation for VEPs.

Citations

• Analysis of visual evoked potentials in patients with neurofibromatosis type 1: new concepts
  Jasna Jancic, Nikola Zarkovic, Blazo Nikolic, Nikola Ivancevic, Branislav Rovcanin, Dejan Nesic
  Frontiers in Neurology.2024;[Epub]     CrossRef
• Usefulness of visual evoked potential monitoring during transsphenoidal surgery: a case report
  Jeong Hwa Rho, Seol-Hee Baek
  Journal of Intraoperative Neurophysiology.2019; 1(1): 32.     CrossRef

Background
Previous studies of radial nerve conduction study (NCS) did not present how to measure the length of the radial nerve across the elbow, and did not even mention how to manage the spiral course of the nerve. This study aimed to applicate the most reliable method to measure the length of the radial nerve during NCS.
Methods
Three points (A, B, and C) were determined along the relatively straight course of the radial nerve. The distance was measured using three different methods: L1) straight distance corresponding to the A-C distance, L2) sum of the distances corresponding to the A-B-C distance, L3) based on the L2, but the elbow is flexed at a 45° angle. We compared the three methods of distance measurement and the calculated nerve conduction velocities (V1, V2, and V3) in normal healthy subjects.
Results
19 normal participants were enrolled. The mean value for method L1, L2 and L3 were 22.5 ± 1.8 cm, 24.0 ± 2.1 cm, and 23.2 ± 2.1 cm (p < 0.001). Calculated conduction velocities using those distance measurement methods as follows (p < 0.001): V1 (60.9 ± 2.7 m/s), V2 (64.6 ± 3.3 m/s), and V3 (63.4 ± 3.9 m/s). V2 was significantly greater than V1 and V3 (p < 0.001, p = 0.010, respectively).
Conclusions
The distance measurement using a stopover point near the lateral epicondyle between two stimulus points in position of a fully extended elbow with forearm pronation is the most appropriate posture for radial motor NCS.