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Ocular neuromyotonia
  1. Ricardo Soares-dos-Reis1,2,
  2. Ana Inês Martins3,
  3. Ana Brás3,
  4. Anabela Matos3,
  5. Conceição Bento3,
  6. João Lemos3,4
  1. 1Neurology Department, São João Hospital Centre, Porto, Portugal
  2. 2Faculty of Medicine, Porto University, Porto, Portugal
  3. 3Neurology Department, Coimbra University Hospital Centre, Coimbra, Portugal
  4. 4Faculty of Medicine, Coimbra University, Coimbra, Portugal
  1. Correspondence to Dr João Lemos, Department of Neurology, Coimbra University Hospital Centre, Coimbra 3000-075, Portugal; merrin72{at}


Ocular neuromyotonia is a rare, albeit treatable, ocular motor disorder, characterised by recurrent brief episodes of diplopia due to tonic extraocular muscle contraction. Ephaptic transmission in a chronically damaged ocular motor nerve is the possible underlying mechanism. It usually improves with carbamazepine. A 53-year-old woman presented with a 4-month history of recurrent episodes of binocular vertical diplopia (up to 40/day), either spontaneously or after sustained downward gaze. Between episodes she had a mild left fourth nerve palsy. Sustained downward gaze consistently triggered downward left eye tonic deviation, lasting around 1 min. MR scan of the brain was normal. She improved on starting carbamazepine but developed a rash that necessitated stopping the drug. Switching to lacosamide controlled her symptoms.

  • ocular neuromyotonia
  • diplopia
  • lacosamide
  • trochear nerve

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  • RS--R and AIM contributed equally.

  • Contributors All authors were responsible for the clinical care of the patient. The initial draft was written by RSR and AIM. AIM and JL recorded the patient video. All authors reviewed and contributed to the final manuscript.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed. This paper was reviewed by Mark Lawden, Leicester, UK.

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  • Editors’ commentary
    Philip E M Smith Geraint N Fuller
  • Editorial
    Mark Lawden

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