Subacute Combined Degeneration

SCD is a myelopathy caused by vitamin B12 deficiency, affecting the dorsal columns and lateral corticospinal tracts. Clinical features include sensory ataxia, paresthesia, and spastic paresis. Pathophysiology involves impaired myelin synthesis and neuronal degeneration. Diagnosis relies on clinical examination, serum B12 levels, and MRI. Management is vitamin B12 replacement; prognosis is favorable if treated early, but prolonged deficiency may result in permanent deficits.