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Brainstem cavernoma presenting with an acute isolated dilated pupil
  1. Sally L Painter1,
  2. Fintan B J Sheerin2,
  3. John S Elston1
  1. 1Department of Ophthalmology, Oxford Eye Hospital, Oxford, UK
  2. 2Department of Neuroradiology, Oxford University Hospitals NHS Trust, Oxford, UK
  1. Correspondence to Sally L Painter, Oxford Eye Hospital, John Radcliffe Hospital, Headley Way, Headington, Oxford OX3 9DU, UK; sallylpainter{at}

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A 29-year-old man presented to the ophthalmic accident and emergency with a 3-day history of blurred vision and a dilated pupil in the left eye. He was previously healthy, reported no drug use or ocular trauma and had no relevant family history. He had no history to suggest inadvertent pharmacological dilatation.

His distance visual acuity was 20/20 OU unaided: near vision was N5 right, N24 left. The left pupil was regularly dilated, measuring 7 mm diameter; it was fixed, with no response to direct or consensual light stimulation or accommodation. The right pupil was 3 mm diameter and had normal responses (figure 1). There was no ptosis on the left, and extraocular movements were full. Convergence was normal, and there was no segmental iris constriction. Neither pupil constricted 25 min after instillation of 0.125% pilocarpine. Pharmacological dilatation was not considered to be likely; therefore, the 1%–2% pilocarpine test was not performed. A provisional diagnosis of acute Adie pupil was made and a review appointment arranged.

Figure 1

A photograph of fixed, dilated left pupil and normal right pupil indicating no ptosis and no tropia in primary position.

A week later, he developed intermittent double vision in down gaze. Two weeks after the initial presentation, the left pupil remained dilated and unreactive, there was no ptosis and his eyes were normally aligned in the primary position. An isolated –1 to 2 deficit of left inferior rectus function was documented. A partial left third nerve palsy was diagnosed and brain imaging arranged.

A CT brain scan demonstrated a high-density lesion on the left of the midbrain tegmentum at the level of the superior colliculus, in the region of the third …

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  • Contributors SLP and JSE wrote the paper and FBJS contributed the radiological descriptions and images.

  • Competing interests None.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.