Neurological symptoms in Megaloblastic anemia

NEUROLOGICAL SYMPTOMS IN MEGALOBLASTIC ANEMIA

Megaloblastic anemia is characterized by defective synthesis of deoxyribonucleic acid (DNA) due to deficiency of Vitamin B12 and Folate
Vitamin B12 is essential for synthesis of Deoxyribonucleic acid, erythropoiesis and synthesis of myelin sheath and its maintenance
Vitamin B-12 plays a major role in providing cofactors that are required to form myelin
Vitamin B-12 is required for the production of methionine — a precursor for S-adenosyl methionine, which is required for methylation reactions. These reactions are essential for myelin maintenance and nerve function
Other reaction which is dependent on vitamin B 12 is isomerization of Methyl Malonyl coenzyme A to Succinyl coenzyme A which requires adenosylcobalamin as prosthetic group on the enzyme Methyl malonyl coenzyme A mutase. Deficiency of Vitamin B12 is associated with increased levels of methylmalonic acid in urine and plasma. This interrupts the reaction and produces consequent build up of Methyl malonate and Propionate. This could lead to the formation and incorporation of abnormal fatty acids into neuronal lipids.
This biochemical abnormality predisposes to myelin breakdown producing neurological complications
Neurological manifestation in megaloblastic anemia include
- Subacute combined degeneration of spinal cord
  - This is due to degeneration of posterior and lateral columns of spinal cord
  - This produces sensory ataxia and loss of position and vibration sense
- Peripheral neuropathy – paresthesia and numbness
- Cerebral changes – leading to dementia, personality changes and sychosis
In elderly patients neurological symptoms may appear without any abnormal hematologic changes or anemia

References

Robbins and Cotrans. Text Book of Pathology. 9 edition
Shirish M Kawthalkar. Essentials of Hematology. First edition. 2006
Dissanayake Mudiyanselage Priyantha Udaya Kumara Ralapanawa, Kushalee Poornima Jayawickreme, Ekanayake Mudiyanselage Madhushanka Ekanayake and Widana Arachchilage Thhilak Ananda Jayalatha. B 12 deficiency with neurological manifestations in the absence of anemia. BMC Res Notes. 2015;8:458

NEUROLOGICAL SYMPTOMS IN MEGALOBLASTIC ANEMIA

Megaloblastic anemia is characterized by defective synthesis of deoxyribonucleic acid (DNA) due to deficiency of Vitamin B12 and Folate

Vitamin B12 is essential for synthesis of Deoxyribonucleic acid, erythropoiesis and synthesis of myelin sheath and its maintenance

Vitamin B-12 plays a major role in providing cofactors that are required to form myelin

Vitamin B-12 is required for the production of methionine — a precursor for S-adenosyl methionine, which is required for methylation reactions. These reactions are essential for myelin maintenance and nerve function

This biochemical abnormality predisposes to myelin breakdown producing neurological complications

Neurological manifestation in megaloblastic anemia include

Subacute combined degeneration of spinal cord

This is due to degeneration of posterior and lateral columns of spinal cord

This produces sensory ataxia and loss of position and vibration sense

Peripheral neuropathy – paresthesia and numbness

Cerebral changes – leading to dementia, personality changes and sychosis

In elderly patients neurological symptoms may appear without any abnormal hematologic changes or anemia

References

Robbins and Cotrans. Text Book of Pathology. 9 edition

Shirish M Kawthalkar. Essentials of Hematology. First edition. 2006

Dissanayake Mudiyanselage Priyantha Udaya Kumara Ralapanawa, Kushalee Poornima Jayawickreme, Ekanayake Mudiyanselage Madhushanka Ekanayake and Widana Arachchilage Thhilak Ananda Jayalatha. B 12 deficiency with neurological manifestations in the absence of anemia. BMC Res Notes. 2015;8:458