Abstract
A 50-year-old white Caucasian woman with previously diagnosed migraine was admitted with unilateral headache and anisocoria. An initial assessment revealed no cause for this abnormality and she was thought to have mydriasis in the context of migraine. However, failure of her symptoms and signs to resolve prompted further investigation and demonstrated the diagnosis of intermittent angle-closure glaucoma.
BACKGROUND
Patients with such a condition can be misdiagnosed as having migraine because attacks tend to subside spontaneously. This case, therefore, underlines the importance of identifying intermittent angle-closure glaucoma as a treatable cause of unilateral headache with anisocoria.
CASE PRESENTATION
A 50-year-old woman was referred by her primary care physician with anisocoria and a unilateral headache. She described a sharp pain behind her left eye associated with blurred vision with this eye open. She also complained of photophobia and phonophobia but did not report any nausea, tearing, nasal stuffiness, eyelid changes or double vision during this episode.
Previous medical history: 5 years of classical migraine on amitriptyline 25 mg nocte as a prophylaxis 2 months prior to her admission.
INVESTIGATIONS
Magnetic resonance image/angiogram of the brain and cerebral arteries were reassuringly normal. An ophthalmological review showed intraocular pressures of 24 mmHg on the right and 58 mmHg on the left. There was marked anisocoria with a dilated left pupil (9 mm), which was both poorly reactive to light, and accommodation reflexes demonstrating only 1 mm of brisk contraction. The right pupil was normal in size and reflexes. Visual acuity was recorded as 6/5 in the right and 6/9 in the left eye with no relative afferent pupil defect. Goldmann visual fields were full in both eyes. Direct ophthalmoscopy failed to demonstrate any segmental abnormalities, vermiform movements and glaucomflecken of the iris. The right optic disc was normal while the left one was suspicious for glaucoma with features of early cupping. The installation of 0.125% pilocarpine eye drops did not result in a significant reduction in pupil size on the affected side. Gonioscopy showed occludable drainage angles with intermittent peripheral anterior synechiae.
DIFFERENTIAL DIAGNOSIS
Migraine
Intermittent angle-closure glaucoma
Posterior cerebral artery aneurysm
Adie’s tonic pupil
Partial third nerve palsy
Contra lateral Horner syndrome
Traumatic mydriasis
Mydriasis secondary to amitriptyline.
TREATMENT
Treatment was with oral acetozolamide and topical apraclonidine 1%. One-hour post-treatment intraocular pressures had normalised (right 14 mmHg, left 17 mmHg).
Bilateral laser iridotomies were subsequently performed, but control of the intraocular pressure has proved difficult due to a trabecular meshwork damaged by recurrent insult.
DISCUSSION
Episodic headaches associated with ocular symptoms are a frequent complaint in both neurological and ophthalmological practice. The observation of mydriasis in patients with migraine headache has been well documented1–5 but alternative diagnoses such as angle-closure glaucoma should also be considered. In angle-closure glaucoma a build up of intraocular pressure is the result of a blockage in the normal drainage channels of the trabecular meshwork and the canal of Schlemm within the angle of the anterior chamber of the eye. Peri-orbital pain, conjunctival reddening, lacrimation and transitory blurring of vision with mydriasis characterise these episodes. Patients often report seeing haloes around objects, especially bright lights, which is related to the development of corneal oedema. This history must be carefully discerned from the visual aura associated with migraine. Further difficulties arise in the diagnosis of intermittent angle-closure glaucoma because between attacks intraocular pressure measurements and visual acuity is often normal. Moreover, symptoms of angle-closure glaucoma are non-specific and they sometimes tend to occur in normal individuals.6 Failure to recognise this diagnosis may be devastating because left untreated, raised intra-ocular pressure may lead to irreversible visual loss.
LEARNING POINTS
Although migraine is one of the most common causes of headache other entities should be kept in mind in the differential diagnosis of intermittent headache.
The absence of characteristic features of glaucoma, such as the typical visual complaint of “seeing halos around lights” and an isolated recording of normal intraocular pressure, does not exclude this diagnosis.
Amitriptyline as a prophylactic treatment for patients with migraine may make individuals more prone to angle-closure glaucoma.
Given the significant risk of permanent optic neuropathy in untreated cases of intermittent angle-closure glaucoma the combination of unilateral headache and mydriasis should prompt an exhaustive effort to exclude this diagnosis.
Footnotes
Competing interests: none.
Patient consent: Patient/guardian consent was obtained for publication.
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