Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 58, Num. 5, 2010, pp. 791-793

Neurology India, Vol. 58, No. 5, September-October, 2010, pp. 791-793

Letter to Editor

MELAS: Recurrent reversible hemianopia

S Aaron¹, A Anupriya², M Sunithi³, V Mathew¹, T Maya¹, MK Goyal¹, M Alexander¹

¹ Neurology Unit, Department of Neurological Sciences, Christian Medical College & Hospital, Vellore, Tamil Nadu, India
² Department of Ophthalmology, Christian Medical College & Hospital, Vellore, Tamil Nadu, India
³ Department of Radiology, Christian Medical College & Hospital, Vellore, Tamil Nadu, India

Correspondence Address:
M Alexander
Neurology Unit, Department of Neurological Sciences, Christian Medical College & Hospital, Vellore, Tamil Nadu
India
mathewalex@cmcvellore.ac.in

Date of Acceptance: 22-Jul-2010

Code Number: ni10220

PMID: 21045518

DOI: 10.4103/0028-3886.72177

Sir,

An 18-year-old engineering student presented with four days' history of decreased vision and low-grade fever. Three weeks earlier, he had noted decreased vision on right gaze, which spontaneously improved within a day. On examination the patient was short stature and was fully conscious and oriented. Neurologic examination showed mild asymmetric ptosis and right incomplete homonymous hemianopia. Non-contrast computerized tomography of brain showed bilateral basal ganglia calcification and magnetic Resonance Imaging (MRI) scan showed non-gadolinium-enhancing T2W hyperintensities in the left parietoccipital areas [Figure - 1], with diffusion weighted/Apparent diffusion coefficient DWI/ADC sequences showing restriction of diffusion [Figure - 2]. He developed 2 episodes of generalized tonic-clonic seizures following MRI. Total white cell count was 13,000/μL (Neutrophils, 87%; Lymphocytes, 10%; Monocytes, 3%). Platelet count was 244,000. ESR was 65 mm (60 minutes), and C-reactive protein and electrolytes were in the normal range. Serum lactate was 1.6 (normal range, 0.3-1.3). Renal and liver function tests were normal, and creatinine phosphokinase levels were normal. Smear for malarial parasites and sickle cell preparation was negative. Antinuclear antibody (ANA), rheumatoid factor, complement, classical antineutrophil cytoplasmic antibodies (C-ANCA), protoplasmic-staining antineutrophil cytoplasmic antibodies (P-ANCA) and lupus anticoagulant were negative. Cerebrospinal fluid (CSF) showed white cell count of 20/μL (polymorphonucleocytes, 18%; lymphocytes, 82%); RBC, 1400/μL; protein, 63 mg%; and glucose, 95 mg% with a corresponding blood sugar of 126 mg%. Encephalitis with an associated infective vasculitis was considered. Patient was treated with IV acyclovir. Results of CSF studies for viral infections obtained later were negative. The vision improved to normal, and the patient was discharged on phenytoin sodium.

After two months, he had a brief period of decrease in his vision following one day of fever. This episode lasted less than a day, and he did not seek any medical help. The patient remained relatively asymptomatic for the next four months, when he had a short febrile illness, following which he complained of progressive visual loss and was readmitted. Neurological xamination revealed left-sided homonymous hemianopia. CSF showed 4 lymphocytes; and RBCs, 10/μL. Serum lactate was elevated 3.8 (normal, 0.3-1.3). MRI scan showed T2W hyperintensities, which were non-contrast-enhancing, mainly involving the right occipital lobe and also posterior parietal and posterior temporal lobes. DWI and ADC sequences showed restricted diffusions in these areas [Figure - 3].

Nerve conduction studies and electromyography were unremarkable. Diagnoses of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) was considered. Blood test confirmed the presence of A3243G mutation in the tRNA gene of mitochondria (DNA PCR and PCR product nucleotide-sequencing method). Treatment with carnithine, coenzyme Q, riboflavin and vitamin C was then initiated. The patient's condition improved, and he has since remained asymptomatic.

Here we have described a case of MELAS presenting with four episoded of transient homonymous hemianopia. The patient's initial presentation was like an encephalitic illness and was treated as one. It is well known for cases of MELAS to mimic herpes encephalitis. ^[1],[2] Some of the features suggestive of mitochondrial cytopathy, which were overlooked during the first admission, were the short stature; bilateral ptosis (which was considered as congenital ptosis); and the mildly elevated serum lactate level (which was attributed to his recent generalized seizure). Brain involvement not following a specific arterial territory and bilateral basal ganglia calcification ^[3] were also helpful clues. Some studies have shown a very rapid normalization of MRI ADC sequences in MELAS as compared to arterial strokes, which can help in differentiating between the two. ^[4],[5]

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