Abstract

Subacute combined degeneration (SCD) of the spinal cord arises from deficiency of cobalamin and may be induced by pernicious anemia (PA) which typically affects patients of Northern European ancestry and tends to occur in the sixth decade of life. We recently cared for a 27-year-old African-American man who presented with numbness of the fingers bilaterally and progressive gait deterioration for six months. He experienced electric-like shocks extending down the spine upon flexing his head (L'Hermitte's sign) intermittently. He was a smoker and consumed moderate amounts of alcohol. His diet was normal and contained animal products, and there was no family or personal history of gastrointestinal or neurologic disease. On examination, his tongue was beefy. His power was mildly decreased at the iliopsoas bilaterally. His reflexes were diminished at the ankles but normal elsewhere, and he had extensor plantar responses. Sensory examination revealed decreased cold sensation in the feet. Vibratory and joint position sensations were decreased in the toes. Romberg's maneuver was positive. His gait was spastic. White blood cell count was 3.1 k/μL (4.0–11.0), hemoglobin 11.7 G/dL (13.5–18), mean corpuscular volume 123 FL (80–96) and his platelet count 68 K/μL. (150–400). Vitamin B₁₂level was 157 pg/mL (211–911). Furthermore, he had a low thyroid stimulating hormone at 0.23 μIU/mL (0.35–5.50) with positive thyroid peroxidase antibodies (16.2 IU/mL) but normal T4, T3 uptake and free T4 index. Positive serum anti-intrinsic factor antibodies were found. Magnetic resonance imaging of the brain and cervical spine was normal. He was treated with a series of five 1000 μg vitamin B₁₂ IM injections and with monthly ones thereafter. His symptoms started improving as early as three weeks into the treatment.