Subacute combined degeneration of the spinal

cord: a brief review.

SCD: Overview

•History of SCD

•Pathophysiology and Pathology

•Imaging Findings

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.

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

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

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

SCD: Pathophysiology

•Causes of B12 deficiency

•GI malabsorption - pernicious anemia (lack of intrinsic factor), post-gastrectomy, Crohn disease, and celiac disease

•Nutritional deficiency

SCD: Pathology

•Loss of myelin in the spinal cord white matter tracts:

•Dorsal columns

•Lateral columns

•Ventral columns

Typical pattern of involvement

AIDS MyelopathySimilar distribution of myelopathy to

SCD

•Pathophysiology is uncertain

•Theories include cytokines secretion from HIV infected monocytes, neurotoxic HIV proteins, inability to use B12 appropriately

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

SCD: Imaging Findings

SCD: Imaging Findings

Note involvement of thoracic and cervical cord.

SCD: Treatment

•In the setting of B12 deficiency, treat with B12.

•Cannot recover lost axons

•Avoid nitrous oxide anesthesia

References

• Pema et al. Myelopathy Caused by Nitous Oxide Toxicity. AJNR, 1998 19:894-896.

• Ravina et al. MR findings in subacute combined degeneration of the spinal cord: a case of reversible cervical myelopathy. AJR, 2000 Mar; 174(3) 863-865.

• Yamada et al. A Case of Subacute Combined Degeneration. Neuroradiology , 1998 40: 398-400.