Abstract
Introduction
Conus medullaris infarction (CMI) is a rare vascular phenomenon that has been scarcely reported in the literature. While previous studies have described the clinical and radiological features of CMI, little attention has been paid to its associated neurophysiological findings.
Methods
We present a case of idiopathic CMI and its neurophysiological findings, then present our findings from a systematic review of other reports of CMI with neurophysiological features found via PubMed search.
Results
Nine articles describing ten cases of CMI with associated neurophysiological data were found, in addition to our case. Out of all 11 cases, 7 cases (64%) had absent F-waves on the first nerve conduction study (NCS) performed as early as 4 h after onset, 5 of whom demonstrated reappearance of F-waves on subsequent follow-up NCS. Seven patients (64%) had diminished compound muscle action potentials (CMAPs), which was usually detectable on NCS performed between day 8 and day 18 of onset. None of them showed recovery of CMAPs in follow-up studies. Four patients (36%) had absent H-reflexes and two patients (18%) had sensory abnormalities. Electromyography (EMG) was reported in seven patients (64%), showing reduced recruitment as early as day 1 of onset, and denervation potentials as early as 4 weeks after onset.
Conclusion
Absent F-waves and diminished CMAPs are the most common NCS abnormalities in CMI. Absent F-waves are detectable very early but tend to recover on subsequent NCS, while diminished CMAPs are detectable later but do not seem to resolve. Further research to determine the utility of neurophysiological studies in CMI diagnosis and prognostication is needed.
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ZT was the primary physician in-charge of the patient described in the case report, did the literature review, prepared the images and tables, and wrote the initial draft of the manuscript. DL was the second investigatory who independently did a literature review for corroboration, and helped to edit the manuscript. KN supervised the process, provided input, and helped to edit the manuscript. All authors reviewed the manuscript.
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Tan, Z., Lo, D.Y.K. & Narasimhalu, K. Neurophysiological findings in conus medullaris infarction—a case report and systematic review of the literature. Acta Neurol Belg (2024). https://doi.org/10.1007/s13760-024-02553-6
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DOI: https://doi.org/10.1007/s13760-024-02553-6