Complete surgical resection is a well-known therapeutic gold standard for spinal ependymoma, but it is associated with high postoperative morbidity. Intraoperative neuromonitoring (INM) is important for detecting and reducing the rate of surgical complications during this operative procedure. We report a case of postoperative paraplegia due to tumor bleeding during the operation. INM of the patient revealed abrupt loss of waveforms during the operation. This finding suggested that INM is helpful for detecting intraoperative hematomyelia and minimizing postoperative neurologic sequelae.

Cortico-cortical evoked potential (CCEP) mapping is a rapidly developing method for visualizing the brain network and estimating cortical excitability. The CCEP comprises the early N1 component the occurs at 10-30 ms poststimulation, indicating anatomic connectivity, and the late N2 component that appears at < 200 ms poststimulation, suggesting long-lasting effective connectivity. A later component at 200-1,000 ms poststimulation can also appear as a delayed response in some studied areas. Such delayed responses occur in areas with changed excitability, such as an epileptogenic zone. CCEP mapping has been used to examine the brain connections causally in functional systems such as the language, auditory, and visual systems as well as in anatomic regions including the frontoparietal neocortices and hippocampal limbic areas. Task-based CCEPs can be used to measure behavior. In addition to evaluations of the brain connectome, single-pulse electrical stimulation (SPES) can reflect cortical excitability, and so it could be used to predict a seizure onset zone. CCEP brain mapping and SPES investigations could be applied both extraoperatively and intraoperatively. These underused electrophysiologic tools in basic and clinical neuroscience might be powerful methods for providing insight into measures of brain connectivity and dynamics. Analyses of CCEPs might enable us to identify causal relationships between brain areas during cortical processing, and to develop a new paradigm of effective therapeutic neuromodulation in the future.

Citations

• The impact of radiofrequency thermocoagulation on brain connectivity in drug‐resistant epilepsy: Insights from stereo‐electroencephalography and cortico‐cortical evoked potentials
  Justyna Gula, Rutger J. Slegers, Raf H. M. Van Hoof, Balu Krishnan, Massimo Mischi, Vivianne H. J. M. van Kranen‐Mastenbroek, Ilse E. C. W. Van Straaten, Danny Hilkman, Louis Wagner, Albert Colon, Olaf E. M. G. Schijns, Borbála Hunyadi, Jacobus F. A. Jans
  Epilepsia.2025; 66(4): 1260.     CrossRef
• Recent developments in stereo electroencephalography monitoring for epilepsy surgery
  Debopam Samanta
  Epilepsy & Behavior.2022; 135: 108914.     CrossRef

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

Intraoperative neuromonitoring (INM) is well known to be useful method to reduce intraoperative complications during the surgery of nervous system lesions. Evoked potentials are most commonly used among the electrophysiological tests. Brainstem auditory evoked potentials are for detecting the problems along the auditory pathways including the eighth cranial nerve and brainstem. Somatosensory evoked potentials are applied for preventing the spinal cord lesions. The INM is affected by many factors. In order to perform an optimal INM, the confounding factors including technical, anesthetical, and individual factors should be kept well under control. INM has frequent electrophysiologic changes during the surgery and it might be helpful to keep one

Various electrophysiological tests have provided a large body of valuable information on neuronal responses to a presentedstimulus. The special and general somatic sensory pathways are main targets of evoked potentials. Two types of evokedpotentials, exogenous and endogenous, are commonly used. Exogenous evoked potentials of general and special somatic sensorysystems will be reviewed. One of general somatic sensory functional pathways, proprioception, can be evaluated by generalsomatosensory evoked potentials with electrical stimulation on nerves. The special somatosensory functional pathways,including vision, and audition, can be evaluated by visual evoked potentials and auditory evoked potentials. Also laser-evokedpotentials are newly developed for pain pathway, including lateral spinothalamic pathway, and vestibular myogenic evokedpotentials for sacculocollic pathways. The evoked potentials of sensory system have maximal clinical utility in evaluatingfunctional deficits along the sensory pathways. They are used for evaluating comatose patients, hysterical patients, prematureinfants, patients with suspected demyelinating diseases or neoplasms, and research. We discuss the neurophysiologic testsof sensory systems in views of practical points. The organized evaluation of sensory electrophysiologic tests can be helpfulin detecting and estimating the abnormalities in neurological diseases.

We present a recordings of 37-year-old woman with simultaneous ictal scalp and subdural electrodes. The ictal rhythmon subdural electrocorticography (ECoG) started earlier (median 24.5 sec) and ended later (median 2.0 sec) compared toictal rhythm on scalp EEG. Eight ictal ECoG recordings were well localized to left temporal area, whereas ictal scalp EEGrecordings were not. Our case shows the obvious timing relations between two recordings, and different electrophysiologicinformation about localization of ictal onset zone.