Subacute Combined Degeneration of the Cord

Question 1

SCDC

Answer 1

Basics
due to vitamin B12 deficiency
dorsal + lateral columns affected
NB joint position and vibration sense lost first then distal paraesthesia
upper motor neuron signs typically develop in the legs, classically extensor plantars, brisk knee reflexes, absent ankle jerks
if untreated stiffness and weakness persist

Question 2

SCDC - Example Question

Answer 2

A 67-year-old woman presents to her GP with progressive numbness and difficulty walking. Furthermore her daughter who was present mentions that she has been behaving strange over the past few months.

She is otherwise fit and well, apart from a ileal resection for treatment-resistant Crohn’s disease 9 years ago.

Laboratory tests showed a low haematocrit and mean corpuscular volume of 110 fL. Blood smear analysis noted macrocytic red blood cells with hypersegmented neutrophils.

Which of the following is the most likely cause of the patient’s presentation?

	Ferrochelatase deficiency
	Folate deficiency
	Intrinsic factor deficiency
	Iron deficiency anaemia
	> Cobalamin deficiency

The ileal resection suggests that the patient is not absorbing the vitamin B12-intrinsic factor complex, leading to vitamin B12 deficiency (aka. cobalamin deficiency), and subsequently subacute combined degeneration. This is further supported by the macrocytic anaemia with hypersegmented neutrophils. Folate deficiency causes the same blood film picture but does not present with neurological symptoms.