Recurrent Alternate-Sided Homonymous Hemianopia Due to Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-Like Episodes (MELAS): A Case Report

Abstract

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) can rarely cause alternate-sided homonymous hemianopia due to stroke-like episodes involving the occipital lobes, as reported in three previously published cases. The authors report an interesting case of a 16-year-old presenting with myoclonic epilepsy due to MELAS with the rare ND3 mitochondrial mutation T10191C, with recurrent alternate-sided homonymous hemianopia. Visual field and corresponding magnetic resonance imaging (MRI) findings are presented. To the authors' knowledge, this is the first report of recurrent alternate-sided homonymous hemianopia in MELAS with documented visual field and MRI findings with resolution between each episode.

Keywords: Case report; MELAS; mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes; recurrent alternate-sided homonymous hemianopia.

Figure 1.

Visual fields (VF). (A) Goldmann VF at initial presentation with left homonymous superior quadrantanopia. (B) Goldmann VF with improvement 11 months later. (C) Humphrey VF with recurrent left homonymous hemianopia 2 years later. Mean deviation (MD): left −11.31 dB, right −8.89 dB. (D) Humphrey VF with improvement 5 months later. MD: left −2.93 dB, right −3.42 dB. (E) Humphrey VF with contralateral right homonymous hemianopia 3 years later. MD: left −25.06 dB, right −10.93 dB.

Figure 2.

Magnetic resonance imaging (MRI) brain axial fluid-attenuated inversion recovery (FLAIR) sequences. (A) Initial presentation with hyperintensities in right occipital and bilateral peri-rolandic areas. (B) Improvement of lesions 9 months later. (C) New bilateral parietal lesions 1 year later. (D) Improvement of lesions 1.5 years later. (E) New left occipital hyperintense lesion 1 year later. (F) New left temporal, parietal, and perisylvian lesions 2.5 years later.