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Editor,—Comitant esotropia is most often acquired at an early age, and is generally benign. However, acute comitant esotropia has also been reported in patients with intracranial diseases including hydrocephalus, Arnold-Chiari malformations, and central nervous system tumours. I describe a case of acute onset comitant esotropia associated with acute demyelinating disease.
An 11 year old boy was referred for evaluation of diplopia. The patient stated he woke up the previous day with double vision. He denied decreased visual acuity, photophobia, pain with eye movements, headache, or nausea and vomiting. One week before the onset of esotropia, he had an upper respiratory infection with a fever that resolved without antibiotics. His mother also noted that he had been very tired over the previous week with episodes of falling asleep during the day at home and school, and one episode of dizziness. He was an otherwise healthy child on no medications and with no allergies.
On examination, visual acuity without correction was 20/20 bilaterally. Pupils were equally reactive without an afferent pupillary defect. Extraocular motility was full, and saccades were grossly normal and symmetrical. Alternate cover testing revealed a comitant 16 prism dioptre esotropia for both near and distance fixation. He was able to fuse with the appropriate prism in place. Slit lamp examination was unremarkable. Dilated retinal examination revealed pink and sharp optic nerves with no papilloedema. Macula, vessels, and retinal periphery were all within normal limits.
The patient underwent magnetic resonance imaging (MRI) the next day (Fig 1). The study revealed a hyperintense signal on T-1 weighted imaging in the area of the periaqueductal grey mater in the midbrain. The lesion was consistent with a demyelinating disease including acute disseminating encephalomyelitis or multiple sclerosis. The patient was referred for neurological evaluation and lumbar puncture the next day. However, on presentation to the paediatric neurologist, the patient noted that his diplopia had gradually resolved. Lumbar puncture was not performed because neurological examination was entirely unremarkable. Follow up ocular examination revealed normal ocular alignment and motility.
Acute onset comitant esotropia is most commonly benign when occurring in infancy or early childhood. Examination to rule out a paretic deviation is essential. However, acute onset of comitant esotropia has also been reported in association with serious neurological disease. It has been reported in association with hydrocephalus.1 These patients generally have obvious neurological problems associated with hydrocephalus, and are not a diagnostic dilemma.2 They may have a meningomyelocele or encephalocele, and an A-pattern esotropia.1 2 In cases of comitant esotropia associated with shunt failure, all the esotropias resolve when the shunts are revised. These patients do not have A-pattern esotropias. Patients may not necessarily present with papilloedema even when hydrocephalus is present.1 In the present case, no hydrocephalus was noted on neuroradiographic study.
Arnold-Chiari malformation has also been reported in association with acute comitant esotropia.2 3 These cases may present with an A-pattern, co-existing nystagmus and hydrocephalus. Arnold-Chiari malformations sometimes do not manifest until late childhood or adulthood, and can be mild. Neuroradiographic study did not reveal Arnold-Chiari malformation in this patient.
Central nervous system tumours have also been reported in association with acute onset comitant esotropias.1 2 4 Tumours in this group include cerebellar astrocytomas, and medulloblastomas, as well as pontine gliomas.1 An A-pattern esotropia is unusual in these patients.2 In a report by Williams and Hoyt, three of their six patients had some form of nystagmus associated with the comitant esotropia. They suggested neurological evaluation in any patient with both nystagmus and acute comitant esotropia. They further suggested evaluation for any patient with acute comitant esotropia if ocular motor fusion can not be established with prism or surgery.1
Acute comitant esotropia has been associated rarely with a hypertensive haemorrhage in the thalamus.5 However, these patients also present with other neurological signs leading rapidly to the diagnosis. In addition, acute comitant esotropia has been reported rarely with myasthenia gravis and seizures.4 6 7
This patient had a brainstem lesion that was consistent with an acute central nervous system demyelination. Its location in the midbrain may have interfered with neurons associated with horizontal gaze centres or vergence mechanisms. This is the first reported case of acute demyelinating disease presenting with acute comitant esotropia. Acute disseminated encephalomyelitis is generally post viral and is characterised by abrupt headache fever, drowsiness, and focal neurological dysfunction. Cerebrospinal fluid analysis may exhibit pleocytosis. It may resolve completely or may result in permanent impairment and seizures.8 Whether this lesion represents a localised variant of acute disseminated encephalomyelitis or multiple sclerosis is not clear. However, cases of acute onset comitant esotropia with suspicious presentations warrant neuroimaging to rule out intracranial pathology including central nervous system demyelinating lesions.
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