1. Subacute combined degeneration of the spinal cord: a brief review.

2. SCD: Overview History of SCD Pathophysiology and Pathology
Imaging Findings

3. SCD: History aka Lichtheim’s Disease
Ludwig Lichtheim described the disease in 1887
Recognized that pathology of cord disease was associated with pernicious anemia and is different from tabes dorsalis.

4. SCD: History aka Putnam-Dana disease
Putnam: series of 8 patients describing the disease
Dana: called it “combined” because it involves the dorsal AND lateral columns

5. SCD: Clinical Findings
Insidious subacute onset of parasthesias, sensory ataxia, hyperreflexia, & + Babinski
symmetric and progresses distal to proximal
megaloblastic anemia and low B12
Severe disability in weeks to months

6. SCD: Pathophysiology B12 Deficiency
Accumulated methylmalonic acid believed to cause myelin toxicity
Possible upregulation of tumor necrosis factor and downregulation of epidermal growth factor
Nitrous oxide
in susceptible patients, B12 is inactivated

7. SCD: Pathophysiology Causes of B12 deficiency
GI malabsorption - pernicious anemia (lack of intrinsic factor), post-gastrectomy, Crohn disease, and celiac disease
Nutritional deficiency

8. SCD: Pathology Loss of myelin in the spinal cord white matter tracts:
Dorsal columns
Lateral columns
Ventral columns
Typical pattern of involvement

9. AIDS Myelopathy Similar distribution of myelopathy to SCD
Pathophysiology is uncertain
Theories include cytokines secretion from HIV infected monocytes, neurotoxic HIV proteins, inability to use B12 appropriately

10. SCD: Imaging Findings
MRI shows, high T2 signal intensity, involving the cervical and/or the thoracic spinal cord in:
Dorsal, lateral and ventral white matter
Cord diameter is normal
No Gd enhancement

11. SCD: Imaging Findings

12. Note involvement of thoracic and cervical cord.
SCD: Imaging Findings
Note involvement of thoracic and cervical cord.

13. SCD: Treatment In the setting of B12 deficiency, treat with B12.
Cannot recover lost axons
Avoid nitrous oxide anesthesia

14. References
Pema et al. Myelopathy Caused by Nitous Oxide Toxicity. AJNR, :
Ravina et al. MR findings in subacute combined degeneration of the spinal cord: a case of reversible cervical myelopathy. AJR, Mar; 174(3)
Yamada et al. A Case of Subacute Combined Degeneration. Neuroradiology , :