27 terms

Subacute Combined Degeneration of Spinal Cord

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What is a differential for systemic diseases that can cause neurologic deficiencies at multiple levels?
HIV associated vacuolar myelopathy
Lyme disease
Multiple Sclerosis
Neurosyphilis
Vitamin B12
Define the spinal cord
tubular structure
originates from medulla and extends through bony spine to the coccyx
What do posterior columns control?
Joint position
Vibration and pressure
What do lateral spinothalamic columns control?
Pain
Temperature
What do ventral corticospinal tracts control?
Motor signals
Usual presentation of Vitamin B12 deficiency?
Parasthesias of hands and feet
Loss of vibratory sense
Diffusely affects the spinal cord-posterior lateral columns
Later: optic atrophy, mental changes, ataxia
What is B12 used in?
DNA synthesis
Methionine synthesis
Conversion of proprionyl into Succinyl coenzyme A from methylmalonate
What factors affect B12 absorption?
Stomach acid
R protein
Intrinsic Factor
Distal 80cm of ileum
Pernicious anemia
-Decreases absorption of B12
-Condition where antibodies are generated against parietal cells
SCD pathology
Edema and destruction of myelin
SCD initial symptoms
Paresthesia in hands and feet
SCD progressive symptoms
sensory loss
gait ataxia
distal weakness, especially in legs
Subacute Combined Degeneration
-syndrome of sensory loss
-spastic paresis associated with pathological lesions in dorsal columns and lateral corticosinal tracts
-macrocytic anemia
Differential Diagnosis for PROGRESSIVE SPASTIC PARAPLEGIA
-degenerative disorders
-demyelinating disorders
-infectious disorders
-inflammatory disorders
-neoplastic disorders
-nutritional disorders
-vascular disorders
-HIV, lyme, MS, neurosyphilis, toxic neuropathy, friedreich ataxia, vit E deficiency
Neurologic manifestations of Vit B12 deficiency
Paresthesia
Peripheral neuropathy
Combined systems disease (demyelination of dorsal columns and corticospinal tract)
Behavioral manifestations of Vit B12 deficiency
Irritability, personality change
Mild memory impairment, dementia
Depression
Psychosis
General manifestations of Vit B12 deficiency
-Lemon-yellow waxy pallor, premature hair whitening
-Flabby bulky frame
-Mild icterus
-Blotchy skin pigmentation in dark-skinned patients
Cardiovascular manifestations of Vit B12 deficiency
Tachycardia
Congestive heart failure
GI manifestations of Vit B12 deficiency
Beefy, red, smooth, and sore tongue
Loss of papillae that is more pronounced along edges
Hematologic manifestations of Vit B12 deficiency
Megaloblastic anemia
Pancytopenia (leukopenia, thrombocytopenia)
Labs for SCD
B12 direct assay
B12 deficiency (levels)
-Serum Cbl <150 pmol/L on 2 separate occasions
-Serum Cbl <150 pmol/L AND total serum homocysteine level >13 umol/L OR methylmalonic acid >0.4 umol/L
How is B12 deficiency compare to folate deficiency?
Folate deficiency mimicks the hematologic manifestations, but does not have the neurologic manifestations
Studies that confirm anatomic and physiologic consequences of B12 deficiency
Nerve conduction studies
MRI
What does MRI of B12 deficiency show?
-Modest expansion of cervical and thoracic spinal cord
-increased signal intensity of T2 weighted images, primarily in the dorsal columns and lateral pyramidal tracts
Treatment
IM Vitamin B12 to build up stores and then on a monthly basis
--> 1000 ug/d for 1 week THEN 1000ug/wk for 1 month
THEN 1000 ug/month until cause of deficiency is corrected OR for life if cause is pernicious anemia
-Treatment can reverse or stop most if not all sequelae of B12 deficiency
What is the difference between B12 deficiency and MS?
MS does not affect peripheral nerve conduction studies bc it is a disease of the Central Nervous system (not peripheral)
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