Subacute Combined Degeneration of Cord due to deficiency of?

Answer is D (Vitamin B12): Subacute Combined Degeneration of Cord (SACD) is caused by vitamin B,2 deficiency. Subacute Combined Degeneration Of Cord is a condition of the spinal cord characterized by demyelination of its neurons due to deficiency of Vit B12,which results in defective/ deficient myelination. Such demyelination occurs predominantly in Posterior column of spinal cord Pyramidal tract of spinal cord Subacute Combined Degeneration of Cord Degeneration/Demyelination of Posterior column of lower cervical & upper thoracic region This is where changes commence. Paraesthaesias, consisting of tingling & numbness and that of pins & needlesQ Loss of vibration sense Q Position sense is involved to a lesser extent. Q Ataxic gait Q Degeneration/Demyelination of Lateral columns (coicospinal tracts) Their involvement follows the involvement of post columns. Motor defecits such as weakness and spasticityQ Increased deep tendon reflexes, clonusQ Plantar extensor Q Spastic gait (Note that gait is initially ataxic but later becomes both spastic and ataxic. Q (at an early stage patellar & achilles reflexes may be diminished, increased or absent).