1. Patient Presentation
A 35-year-old man presented to the emergency department (ED) with “right eye paralysis, unequal pupils, and migraines” for 1 week. He had been evaluated at an outside hospital 1 week prior with a noncontrast computed tomography (CT) of the head that did not demonstrate any acute intracranial abnormality. He was discharged home with instructions to follow up with an ophthalmologist. He presented to our ED with a physical examination notable for a “down and out” positioned right eye with right-sided ptosis and mydriasis. CT angiography (CTA) of the head and neck was obtained and demonstrated a posterior communicating (PCOM) artery aneurysm (Figure 1, Figure 2, Figure 3, Figure 4). Neurosurgery was consulted, and a right craniotomy was performed for clipping of the aneurysm.
Figure 1.
Computed tomography in axial plane demonstrating a right posterior communicating artery aneurysm (arrow).
Figure 2.
Computed tomography in sagittal plane demonstrating a right posterior communicating artery aneurysm (arrow), measuring 8.1 mm × 4.7 mm.
Figure 3.
Computed tomography in coronal plane demonstrating a right posterior communicating artery aneurysm (arrow).
Figure 4.
Three-dimensional reconstruction of cerebral vasculature with evidence of an aneurysm (arrow).
2. Diagnosis: PCOM Artery Aneurysm
Cranial nerve III (CN III) provides skeletal motor innervation to 4 muscles of the eye as well as the levator palpebrae superioris muscle of the eyelid and autonomic parasympathetic innervation to the sphincter pupillae and ciliary muscles. Loss of function leads to unopposed lateral rectus and superior oblique muscles and loss of sympathetic influence, producing a “down-and-out” gaze, ptosis, and dilated, nonaccommodating pupil.1 Given the association between a PCOM aneurysm and CN III palsy, a new CN III palsy should raise suspicion for compressive pathologies like aneurysm.2 Even pupil-sparing or otherwise partial CN III palsies may be due to cerebral aneurysm and should prompt suspicion.3,4 Noncontrast CT is not an adequate modality for diagnosing unruptured aneurysms.5,6 CTA and magnetic resonance angiography are first-line modalities due to their high sensitivity and specificity.5
Funding and Support
By JACEP Open policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist.
Conflict of Interest
All authors have affirmed they have no conflicts of interest to declare.
Footnotes
Supervising Editor: John Rogers, MD
References
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