‘Mobile phone sign’ in early vitamin B12 deficiency

Sir, A healthy 54-year-old computer engineer became concerned enough to consult his primary-care physician when he noticed he could no longer feel his mobile phone ‘ring’ when it was in ‘vibration only’ mode in his pocket. A review of his health failed to reveal any other complaint, except some memory disturbances, which were fairly recent. Physical examination was entirely normal, except for a significantly decreased vibration sense. Blood tests were notable only for low serum B12 levels (150 pg/ml, normal 222–1132 pg/ml). There was …