Insight Into Uncommon Territory: Exploring Internuclear Ophthalmoplegia in Artery of Percheron Infarct

Abstract

Internuclear ophthalmoplegia (INO), a neurological disorder is characterized by horizontal gaze palsy because of a lesion in the medial longitudinal fasciculus, a neural pathway that is mainly responsible for coordinating the movements of the eye. INO presents with diplopia and impaired adduction of the affected eye, accompanied by abducting eye nystagmus. The condition also arises from different etiologies which include multiple sclerosis, encephalitis, Lyme disease, HIV, and herpes zoster. Artery of Percheron (AOP) infarction is a subtype of bilateral thalamic infarction that poses a unique form of diagnostic perplexity due to its varied and often non-specific clinical manifestations such as altered responsiveness, memory disturbances, and oculomotor deficits. Here we discuss a 53-year-old female who presented with INO in the context of an AOP infarct. Under this context, the clinical finding includes some paradigms like nystagmus, anisocoria, and bilateral ptosis. Magnetic resonance imaging confirmed an acute infarct in the AOP territory, which supplies the rostral midbrain and paramedian thalami. This case emphasizes the critical importance of meticulous clinical evaluation and the utilization of advanced imaging techniques in diagnosing rare stroke syndromes like AOP infarction. Management of the patient included dual antiplatelet therapy to prevent further thromboembolic events and supportive care to address the immediate neurological deficits. Early recognition and prompt treatment are crucial for better patient outcomes. Long-term management focuses on the secondary prevention of stroke through lifestyle modifications, medical therapy, and regular monitoring. Education on uncommon stroke syndromes and continued research are essential for enhancing the accuracy of diagnosis and efficacy of treatment which ultimately leads to better patient care and prognosis.

Keywords: artery of percheron; internuclear ophthalmoplegia; medial longitudinal fasciculus; stroke syndromes; thalamic infarction.

Figure 1. Details of eye examination

(A) The image displays unequal drooping of both eyelids and more pronounced ptosis observed on the right side(white arrow). (B) Restricted inward movement of the right eye (red arrow) during leftward gaze. (C) Unaffected ocular movements during rightward gaze.

Figure 2. Computed tomography (CT) scan of the brain

CT brain axial view displaying distinct area of hypoattenuation in the bilateral paramedial thalamus(right thalamus, red arrow; left thalamus, yellow arrow) advancing into bilateral midbrain resulting in impingement of third ventricle in its posterior aspect.

Figure 3. Magnetic resonance imaging (MRI) of the brain

MRI findings: (A) - Axial T1: Hypointense signals in both thalami, more on the right. (B)/(C) - Transverse T2/FLAIR: Hyperintense signals in bilateral thalamus, predominantly right, extending to midbrain. (D) and (E) - Diffusion-weighted imaging and Asymmetric diffusion coefficient map: Asymmetric diffusion restriction in bilateral thalamus, primarily on the right side expanding to bilateral midbrain paramedian to midline. Right thalamus, red arrow; left thalamus, yellow arrow. Focal mass effect in the form of mild effacement of the third ventricle – all these features suggestive of acute infarct. FLAIR, fluid-attenuated inversion recovery.