MEDizzy - A 34-year-old woman with diabetes presents to your office

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Cranial Nerves and Neuro ophthalmology

A 34-year-old woman with diabetes presents to your office complaining of mild left eye ache and an increased left pupil size that she noticed in the mirror yesterday. On examination, you find that her right pupil reacts normally to light, but her left pupil is nonreactive to direct and consensual light, or to accommodation. What do you suspect as the likely cause?

ExplanationD. This patient has an idiopathic tonic (Adie’s) pupil. It is thought to result from a lesion in the postganglionic parasympathetic pathway to either the ciliary ganglion or the short ciliary nerves and is most often attributed to viral etiology, although evidence is lacking. Acutely, there is unilateral mydriasis and the pupil does not constrict to light or accommodation because the iris sphincter and ciliary muscle are paralyzed. Sectoral palsy of part of the iris sphincter may be involved, and is considered the earliest and most specific feature. Patients often complain of photophobia, visual blurring, and ache in the orbit. Within a few days to weeks, denervation supersensitivity to cholinergic agonists develops and this is most often tested with low-concentration pilocarpine 0.125%, in which the tonic pupil will constrict but the normal pupil is unaffected by the low concentration. Eventually, slow, sustained constriction to accommodation and slow redilation after near constriction occur, and the baseline pupil decreases slightly in size (in ambient light), whereas the other features remain. In general, the chronic stage is characterized by the pupillary light reflex rarely improving, whereas the accommodation reflex does improve, although it often remains slower (tonic). This is termed “light-near dissociation.” It is sometimes associated with diminished or absent deep tendon reflexes and this is referred to as “Holmes–Adie syndrome,” or Adie’s syndrome. Argyll Robertson pupils are classically associated with neurosyphilis. They are characterized by bilateral irregular miosis with little to no constriction to light, but constriction to accommodation without a tonic response as opposed to Adie’s pupil. Optic neuritis would be associated with a relative afferent pupil defect. An aneurysm would likely have more oculomotor involvement (although not necessarily). Diabetic oculomotor neuropathy is classically associated with pupil sparing, although the appearance of Argyll Robertson pupils can occur as well.