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B12 Deficiency Neuropathy — RACP Adult Medicine MCQ

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ModerateGeneral Internal MedicineB12 Deficiency NeuropathyRACP Adult Medicine

A 65-year-old woman presents with progressive painful sensory neuropathy affecting her feet. She has macrocytic anaemia (MCV 112 fL) and a smooth, red tongue. Serum vitamin B12 is 85 pmol/L (low). She has positive anti-intrinsic factor antibodies. What additional neurological finding may be present?

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Correct answer: C — Cerebellar ataxia

Vitamin B12 deficiency from pernicious anaemia (anti-intrinsic factor antibodies) causes subacute combined degeneration of the spinal cord, affecting the dorsal columns (proprioception loss, sensory ataxia) and lateral corticospinal tracts (spasticity, hyperreflexia, extensor plantars). Peripheral neuropathy (LMN) coexists, so reflexes may be diminished despite UMN pathology. Macrocytic anaemia, glossitis, and neuropsychiatric symptoms are other features. Treatment is IM hydroxocobalamin 1 mg injections.

Reference: eTG – 2025 – Neurology; eTG – 2025 – Haematology