Article

An unusual case of diplopia

Asking the right questions leads to the correct diagnosis.

Our patient was a 70-year-old African-American male with noninsulin-dependent diabetes who presented with a two-month history of two episodes of episodic vertical diplopia, each episode lasting 15 to 20 minutes. He denied associated ptosis.

THE WORK-UP

Our differential diagnosis included microvascular nerve palsy, compressive lesion of the orbit, myasthenia gravis, giant cell arteritis (GCA) and skew deviation. Upon further questioning, the patient reported fatigue, right-sided headache, jaw claudication, and joint pain. This led to a focused exam with the following pertinent findings:

Head: +tenderness to palpation of the scalp

Distance visual acuity with correction: 20/15 OD, 20/20 OS

Pupils: briskly reactive without afferent pupillary defect OU

Alignment: 1 PD right hypertropia in primary, up-gaze and left gaze 2 PD right exophoria in primary gaze, 1 PD right exophoria in up-gaze

Motility: Full bilaterally

Dilated fundus exam: Normal nerve, macula, vessels and periphery OU

An MRI of the brain/orbits and MRA of the head/neck were negative. The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were elevated to 48 mm/hr and 3.0 mg/L, respectively. The constellation of clinical symptoms including episodic diplopia, constitutional symptoms of headache, scalp tenderness, jaw claudication and fatigue with elevated inflammatory markers pointed to a diagnosis of GCA. The patient was started on high-dose systemic steroids and his symptoms improved within 72 hours. A temporal artery biopsy was performed, demonstrating diffuse mononuclear cell infiltrate with giant cells at the intima-media junction, confirming GCA.

THE DIAGNOSIS

Giant cell arteritis (GCA) is an idiopathic inflammatory disorder leading to vascular obstruction of medium- to large-sized arteries, most often in individuals over 50 years of age. (Figure 1)1,2 While the classic presentation involves arteritic anterior ischemic optic neuropathy, GCA has a wide range of ocular and extraocular manifestations, including diplopia. Incidence of GCA presenting as diplopia varies from 5.9% to 33.3%.3-5 The diagnosis is usually made clinically and confirmed by the presence of elevated ESR, CRP and platelets with a positive and temporal artery biopsy.6 Timely diagnosis is crucial as GCA can threaten both vision and life if left untreated. Treatment involves high-dose systemic steroids for several months with close monitoring of inflammatory markers and recurrence of clinical symptoms. Some studies have shown interleukin-6 blockers to be effective nonsteroidal alternatives in refractory cases.7-9

Figure 1. Temporal artery biopsy demonstrating diffuse mononuclear cell infiltrate with giant cells involving the arterial wall intima and media.

THE LESSON

Ophthalmologists must maintain a high index of suspicion for GCA in patients over 50 years of age presenting with diplopia, taking care to obtain a thorough review of systems and order appropriate laboratory studies. OM

REFERENCES

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