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					ARCH SOC ESP OFTALMOL 2008; 83: 673-674                                          SHORT COMMUNICATION

                                   OCULAR NEUROMYOTONIA
                                        NEUROMIOTONÍA OCULAR

                       ABSTRACT                                             RESUMEN
Case report: We describe a 58-year-old man,               Caso clínico: Se describe un paciente de 58 años,
without history of radiation therapy, who presented       sin antecedentes de radioterapia, que presenta epi-
with transient episodic diplopia following sustained      sodios de diplopía después de una mirada lateral y
lateral gaze lasting around 30-50 seconds. He deve-       mantenida de 30-50 segundos de duración. Durante
loped a large angle exotropia of the left eye that gra-   el episodio desarrolla una exotropía de gran ángulo
dually returned to normal after 50 seconds. Between       en el ojo izquierdo retornando a la normalidad des-
episodes he was asymptomatic. Partial resolution of       pués de 50 segundos. El paciente se encontraba
his symptoms was obtained after treatment with            asintomático entre los episodios de diplopía. El
carbamazepine.                                            paciente fue tratado con carbamacepina con resolu-
Discussion: Neuromyotonia must be considered              ción parcial de los síntomas.
when evaluating a patient with intermittent diplopia      Discusión: La neuromiotonía ocular debe ser con-
(Arch Soc Esp Oftalmol 2008; 83: 673-674).                siderada cuando se evalúa un paciente con diplopía
Key words: Ocular neuromyotonia, intermittent
diplopia, intracranial disease, carbamazepine.            Palabras clave: Neuromiotonía ocular, diplopía
                                                          intermitente, enfermedad intracraneal, carbamace-

                  INTRODUCTION                                           CASE REPORT
  Ocular neuromyotonia (ON) is a rare ocular                A 58-year-old man without relevant history
motility disease characterized by the involuntary         went to the emergency service referred by his pri-
contraction of one or more ocular muscles (1).            mary care physician to discard «retinal patholo-
Generally it is secondary to other associated             gies» due to intermittent diplopia starting one year
processes, although idiopathic cases have been            ago but more frequent in the last week. The
described (2, 3). In this paper we present a typi-        patient’s profession is truck driver. He referred
cal ocular neuromyotonia case defined as idio-            between 10 and 15 events of horizontal diplopia
pathic.                                                   per day, each lasting 30-50 seconds only when

Received: 24/9/07. Accepted: 13/10/08.
Medina del Campo General Hospital. Valladolid. Spain
1 Ph.D. in Medicine.
2 Graduate in Medicine.

V.M. Asensio Sánchez
Hospital General Servicio Castellano-Leonés de Salud
Medina del Campo (Valladolid)

looking through the left rear view mirror. After
each event no symptoms appeared until the next
episode. In exploration, ocular motility was nor-
mal (fig. 1), although after fixing the gaze to the
left, a 20-degree exotropy developed (fig. 2) which
resolved spontaneously after 50 seconds. The
orbitary and cranial nuclear magnetic resonance
study was normal. The edrophonium test was neg-
ative. Treatment was initiated with carba-
mazepine, first 200 mg and subsequently 400 mg
per day, producing a considerable improvement in
symptoms. The patient referred a 50% reduction in
the number and intensity of daily episodes, with-
out complete remission.                                   Fig. 2: horizontal diplopia. Exotropy of about 20 degre-
                                                          es after prolonged left gaze. After 50 seconds, motility
                                                          returned to normal.
                                                          and/or parasellar region or two compressive
   Ocular neuromyotonia is a rare clinical process        lesions in the ocular motors (2, 3, 5). Any motor
characterized by contraction of one or several ocu-       nerve could be affected.
lar muscles. This contraction is a generally spon-           Ophthalmological exploration in these patients
taneous or occurs in an attempt to fix the gaze and       can yield normal results and only after prolonged
represents the severest phenotype of hyper-               periods of fixation or eccentric gaze the character-
excitability of ocular cranial nerves (1, 4). Inap-       istic findings may emerge. In the literature, only
propriate discharges of the ocular motor nerve            six cases were found as idiopathic ocular neu-
neurons and/or instability of cellular membranes          romyotonia. This paper presents a 50-year-old
could account for the contraction. About 40% of           patient with neuromyotonia of the VI left cranial
patients with acquired neuromyotonia exhibit anti-        pair without a history of radiotherapy treatment in
bodies against potassium channels (1, 4, 5).              which no lesion was found, accordingly it was
Processes such as ocular myasthenia, demyeliniz-          considered as idiopathic ocular neuromyotonia.
ing diseases, uncompensated phoriae, Graves dis-          ON patients benefit from medications such as car-
ease, convergence spasm and myochemia of the              bamazepine as membrane stabilizers (1-5), and all
superior oblique must be considered in the differ-        that must be studied to discard intracranial dis-
ential diagnostic (5). In most described ON cases         eases.
there is a history of surgery, more specifically
brain radiotherapy, due to tumors in the sellar
                                                           1. Frohman EM, Zee DS. Ocular neuromyotonia: clinical
                                                              features, physiological mechanisms, and response to the-
                                                              rapy. Ann Neurol 1995; 37: 620-626.
                                                           2. Hadjikoutis S, Morgan JE, Wild JM, Smith PE. Ocular
                                                              complications of neurological therapy. Eur J Neurol
                                                              2005; 12: 499-507.
                                                           3. Tilikete C, Vial C, Niederlaender M, Bonnier PL, Vighet-
                                                              to A. Idiopathic ocular neuromyotonia: a neurovascular
                                                              compression syndrome? J Neurol Neurosurg Psychiatry
                                                              2000; 69: 642-644.
                                                           4. Yee RD, Purvin VA, Azzarelli B, Nelson PB. Intermittent
                                                              diplopia and strabismus caused by ocular neuromyotonia.
                                                              Trans Am Ophthalmol Soc 1996; 94: 207-223.
                                                           5. Ezra E, Spalton D, Sanders MD, Graham EM, Plant GT.
Fig. 1: 58-year old male with normal ocular motility.         Ocular neuromyotonia. Br J Ophthalmol 1996; 80: 350-355.

674                                  ARCH SOC ESP OFTALMOL 2008; 83: 673-674