A Case of Downbeat Nystagmus Induced by Carbamazepine Intoxication

DOI Web Site 12 References
  • Matsuda Kazunori
    Department of Otolaryngology, Tokushima Prefectural Central Hospital Department of Otolaryngology, University of Tokushima School of Medicine
  • Sato Go
    Department of Otolaryngology, University of Tokushima School of Medicine
  • Fukuda Junya
    Department of Otolaryngology, University of Tokushima School of Medicine
  • Takaoka Sho
    Department of Otolaryngology, University of Tokushima School of Medicine
  • Tomura Miki
    Department of Otolaryngology, Tokushima Prefectural Central Hospital Department of Otolaryngology, University of Tokushima School of Medicine
  • Matsuoka Momoyo
    Department of Otolaryngology, University of Tokushima School of Medicine
  • Azuma Takahiro
    Department of Otolaryngology, University of Tokushima School of Medicine
  • Kitamura Yoshiaki
    Department of Otolaryngology, University of Tokushima School of Medicine
  • Imai Takao
    Department of Otolaryngology - Head and Neck Surgery, Osaka University Graduate School of Medicine
  • Takeda Noriaki
    Department of Otolaryngology, University of Tokushima School of Medicine

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Other Title
  • カルバマゼピン中毒により下眼瞼向き眼振を認めた薬剤性めまい症例

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Abstract

<p>　We report the case of a 33-year-old man who presented with disequilibrium and downbeat nystagmus. Balance testing showed failure of visual suppression of caloric nystagmus with insufficient optokinetic nystagmus responses, suggesting central vestibular dysfunction. However, MRI showed no lesions in the brain, including in the cerebellum. The patient had been diagnosed previously as having epilepsy, and the convulsions had remained under control for more than 10 years with a maintenance dose of carbamazepine (900mg/day). Blood tests revealed a serum level of carbamazepine of 10.7mEq/l, which was over the therapeutic range (4.0-10.0mEq/l). Therefore, his carbamazepine dose was reduced, and with a reduction of the dose to 600mg/day, his disequilibrium and downbeat nystagmus gradually disappeared, along with a decrease in return of the serum level of carbamazepine to the therapeutic range. Therefore, we diagnosed the disequilibrium with downbeat nystagmus in this patient as having been caused by carbamazepine intoxication. Although carbamazepine is metabolized by CYP3A4 in the liver, elevated levels of the drug have been reported in cases of renal failure. As he also suffered from polycystic kidneys, we consider that the progressive renal dysfunction in our patient could have precipitated the carbamazepine intoxication.</p>

Journal

  • Equilibrium Research

    Equilibrium Research 82 (1), 26-33, 2023-02-28

    Japan Society for Equilibrium Research

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