Subacute combined degeneration of the spinal cord a

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 B 12 • Severe disability in weeks to months

SCD: Pathophysiology • B 12 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, B 12 is inactivated

SCD: Pathophysiology • Causes of B 12 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 Myelopathy Similar distribution of myelopathy to SCD • Pathophysiology is uncertain • Theories include cytokines secretion from HIV infected monocytes, neurotoxic HIV proteins, inability to use B 12 appropriately

SCD: Imaging Findings • MRI shows, high T 2 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 B 12 deficiency, treat with B 12. • 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.