Leber Hereditary Optic Neuropathy Associated with Malabsorption Syndrome After Bariatric Surgery

Abstract

We report a patient who developed bilateral visual loss from Leber hereditary optic neuropathy (LHON) in conjunction with chronic malabsorption consequent to bariatric surgery. A 31-year-old man reported visual loss in his left eye and, 2 weeks later, in his right eye. His vision gradually worsened down to finger counting at a distance of 1 m, and he was admitted to the hospital for study. He had undergone vertical banded gastroplasty for morbid obesity 3 years earlier. He smoked 10 cigarettes/day and drank a few alcoholic drinks on weekends. Past ocular history was negative. Family history was remarkable for a maternal cousin with a history of unexplained poor vision since childhood. On our examination, visual acuity was 20/40 in the right eye and 20/200 in the left eye. There was a dense central scotoma in the visual field of the left eye and a pale optic disc in that eye. There was an afferent pupil defect on the left. No other ocular findings were detected, and results of the neurologic examination were unremarkable. Results of extensive hematologic, serologic, and cerebrospinal fluid studies were all normal or negative except for decreased serum levels of vitamin E at 3.4 μg/mL (normal range 5-20 μg/mL), borderline serum levels of vitamin B12 and folate (253 pg/mL and 3.6 ng/mL, respectively), and increased mean corpuscular volume at 101 fL. Results of CT and MRI of the brain and orbits were normal. Pattern-reversal visual evoked potentials revealed marked bilateral delay with P100 latencies of 130.8 ms from the right eye and 156.3 ms from the left eye. The patient received treatment with 1,000 mg/day methylprednisolone intravenously for 5 days, as well as oral vitamin B complex and vitamin E. There was no improvement in vision during his hospitalization. Genetic testing, performed at Public Foundation of Genomic Medicine (Santiago de Compostela, Spain), showed a homoplasmic mitochondrial DNA (mtDNA) mutation at position 11778A, confirming the clinical diagnosis of LHON. On a 10-month follow-up, clinical examinations showed no substantial changes. We have described a young man with a LHON mtDNA mutation and a history of moderate alcohol and tobacco abuse who developed subacute bilateral optic neuropathy in the setting of chronic malabsorption (multiple vitamin deficiency) induced by bariatric surgery. Epigenetic factors are reported to contribute to the clinical expression of LHON mtDNA mutations, including tobacco smoking, alcohol consumption, uncontrolled diabetes, ethambutol use, and antiretroviral therapy (1). There are similarities between the optic neuropathies of LHON, vitamin B1 deficiency, and vitamin B12 deficiency, suggesting that abnormalities of adenosine triphosphate levels might be the common underlying pathogenetic mechanism (2). In our patient, tobacco smoking and alcohol consumption may have contributed. Visual loss began after bariatric surgery, perhaps in the context of malabsorption. Asymptomatic 11778 mtDNA LHON carriers frequently show manifestations of optic nerve impairments in relation to environmental factors (3), just as mutations in the 12S rRNA gene of the mitochondrial genome increase susceptibility to the ototoxicity of aminoglycoside antibiotics (4). Three cases of LHON in subjects who also had low serum vitamin B12 levels at the time of symptom onset have recently been reported (5). Taken together, these observations suggest that optic neuropathy in patients carrying a primary LHON mtDNA mutation may be precipitated by vitamin deficiency. Patients who have undergone bariatric surgery show multiple biochemical abnormalities consistent with malabsorption, including low serum levels of vitamin B12, vitamin D, vitamin E, calcium, copper, or zinc. Some patients develop encephalopathy, optic neuropathy, posterolateral myelopathy, acute polyradiculoneuropathy, and polyneuropathy. Perhaps a positive family history of visual loss should prompt mtDNA investigations before bariatric surgery is considered. Diego Santos-García, MD, PhD Javier Abella, MD Section of Neurology Hospital A. Marcide Ferrol, Spain Begoña De Domingo, MD Service of Ophthalmology Hospital A. Marcide Ferrol, Spain Raúl de la Fuente-Fernández, MD Section of Neurology Hospital A. Marcide Ferrol, Spain [email protected]