Neurological deficits in a patient with selenium deficiency due to long-term total parenteral nutrition

Abstract

The neurological symptoms of selenium deficiency are unclear. We report a patient with neurological deficits associated with selenium deficiency following long-term total parenteral nutrition (TPN). A 40-year-old man was referred complaining of visual loss followed by slurred speech and staggering gait that had developed over the preceding 2 months. He had suffered from Crohn’s disease for 22 years and had received home TPN management for 3 years following extensive surgical resection of the gastrointestinal tract. As a result of shortbowel syndrome, he received only a little water and gastric coating agents. Neurological examination showed visual loss, bradyarthria, truncal and limb ataxia, and loss of limb proprioception. Physical examination showed curly hair and whitened nail beds on the fingers and toes, which had developed 3 months before the neurological manifestations (Fig. 1a, b). Brain magnetic resonance (MR) imaging and MR spectroscopy appeared normal. Ophthalmological examination showed large optic disc cupping, concentric visual field constriction and diminished flicker sensitivity without elevation of intraocular pressure, suggesting optic nerve disorder. Blood examination revealed an elevated mean corpuscular volume (MCV) of 109.1 fl. Blood concentrations of vitamins A, B1, B2, B6, B12, C and E, folic acid and trace metals (Fe, Cu, Zn, Pb and Al) were all normal. Serum inflammatory and autoimmunological markers, including antineuronal antibodies, and cerebrospinal fluid findings showed no abnormalities. Clinical history, nail and hair abnormalities, and macrocytosis were suspicious for selenium deficiency. The serum selenium level was below the detection limit of 2.0 lg/dl. He was diagnosed with systemic dysfunctions caused by selenium deficiency, and 100 mg/day sodium selenite was administered intravenously. By continuous administration, his curly hair and whitened nail beds gradually disappeared (Fig. 1c, d), and the MCV returned to normal over several months. Although deterioration of his neurological symptoms stopped shortly after initiation of replacement, improvements were insufficient to allow resumption of daily activities. Visual, speech and gait disturbances were unchanged by 3 years of selenium replacement. Selenium is an essential trace element that acts as an antioxidant in tissues [1, 2]. Selenium deficiency may occur as a result of long-term unphysiological nutrition, and is known to present macrocytosis [3], nail bed or hair abnormalities [3–5], skeletal muscle disorders [6, 7] and cardiomyopathy [8], between 1 month and 6 years [6, 8, 9]. The scarcity of cases, however, means that the neural symptoms of selenium deficiency remain unknown. To the best of our knowledge, only seven cases with neurological symptoms have been reported, including the present and three in Japanese abstracts (not available via MEDLINE) [10, 11]. Visual disturbance was the major symptom in six of these, and other neurological symptoms included consciousness disturbance, dysarthria, spasticity of the extremities, ataxia and sensory disturbances. These were manifested over 1–12 years after initiating TPN or T. Oguri M. Hattori T. Yamawaki N. Matsukawa (&) K. Ojika Department of Neurology and Neuroscience, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-ku, Nagoya 467-8601, Japan e-mail: norim@med.nagoya-cu.ac.jp