Neurology: Case of the Month

Test Yourself — Patient 18

Vitamin B12 Deficiency

1. Dysfunction in the following anatomical location is thought to be associated with Lhermitte's phenomenon:
   • [ A ] Posterior root ganglia in the high thoracic cord
   • [ B ] Nucleus cuneatus in the mid pons
   • [ C ] Corticospinal tracts in the mid-cervical cord
   • [ D ] Nucleus gracilis in the low-mid medulla
2. All of the following statements are TRUE regarding vitamin B12, EXCEPT:
   • [ A ] About 90% of the total vitamin B12 is stored in the liver.
   • [ B ] Vitamin B12 is also known as cyanocobalamin.
   • [ C ] Vitamin B12 is abundant in most vegetables.
   • [ D ] Vitamin B12 binds to intrinsic factor in the stomach.
3. The following sign/symptom is NOT commonly associated with vitamin B12 deficiency:
   • [ A ] Loss of vision
   • [ B ] Spastic paraplegia
   • [ C ] Confusion and hallucinations
   • [ D ] Loss of pain and temperature
4. All of the following statements are TRUE, EXCEPT:
   • [ A ] If the Schilling test is abnormal, the serum cobalamin level will also be abnormal.
   • [ B ] Hematological abnormalities, including a macrocytic anemia, may be seen.
   • [ C ] A leukoencephalopathy may be the presenting symptom/sign, even in the absence of myelopathy.
   • [ D ] Nerve conduction studies show small or absent sural nerve potentials in about 80% of patients.
5. All of the following are correct regarding vitamin B12 deficiency, EXCEPT:
   • [ A ] On pathology, spongy changes and foci of myelin and axon destruction are commonly seen in the white matter of the spinal cord.
   • [ B ] Prolonged nitrous oxide exposure may mimic a clinical syndrome identical to that of vitamin b12 deficiency.
   • [ C ] Improvement is not expected until 12 months following therapy.
   • [ D ] Rare cases of dietary insufficiency can be seen in strict vegetarians without evidence of malabsorption.

 

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