A 48 year-old- man presents to your office complaining of dizziness, postural lightheadedness, fatigue, weakness, stiff, rigid muscles, and pins and needles sensation in both hands and legs. His vision is not normal. He is having a ‘foreign body sensation in both his eyes’. He went to see an optometrist, who examined him and informed him that the retinal examination is normal and who advised him to use Systane lubricant eye drops. His wife told him that his pins and needles sensation in both hands could be due to excessive use of his computer keyboard and advised him to ‘stay away from your computer and iPad’. He also holds the side bars with both hands while running on his treadmill and thought excessive pressure on both hands could be the cause of his pins and needles sensation in both his hands. He decreased his computer screen time and exercise time. However, his symptoms are only getting worse over the last 6 months. On physical examination, you note that he has pallor, scleral icterus, lemon-tinged skin, smooth, beefy red tongue, systolic ejection murmur, spasticity, clonus, poor position and vibration sense, increased Babinski reflex and memory loss. Lhermitte sign and Romberg tests are positive. The blood film showed coarsely stippled red blood cells, oval macrocytes, anisocytosis, poikilocytosis and neutrophils with 7 lobes. Other laboratory tests reveal the following: Erythrocyte count (RBC) 2.9 million/mm³ Male: 4.3 – 5.9 million/mm³ Female: 3.5 – 5.5 million/mm³ Hemoglobin, blood 9.7 g/dL Male:13.5-17.5 g/dL Female 12.0 – 16.0 g/dL Reticulocyte count 0.6% 0.5% – 1.5% Mean corpuscular volume (MCV) 109 μ m³ 80-100 μ m³ Methylmalonic acid, serum 589 nmol/liter 0−378 nmol/L Homocysteine, serum 24 micromoles/liter <15 micromoles/L indirect bilirubin, serum 1.2 mg/dl 0.2 - 0.8 mg/dL Lactate dehydrogenase 195 U/L 45 - 200 U/L What is the most likely diagnosis in this patient?
