A 65-year-old woman was found dead in her house. The family notes that she had difficulty walking over the past few months. The patient had a history of atrial fibrillation treated with anticoagulation therapy. Gross examination shows bruising of the scalp. Autopsy reveals a large epidural hemorrhage with brain herniation; spinal cord evaluation reveals symmetric myelin layer vacuolization and axonal degeneration involving the posterior columns and the lateral corticospinal tracts. Which of the following is the most likely cause of this patient's spinal cord findings?

Question

A 65-year-old woman was found dead in her house.  The family notes that she had difficulty walking over the past few months.  The patient had a history of atrial fibrillation treated with anticoagulation therapy.  Gross examination shows bruising of the scalp.  Autopsy reveals a large epidural hemorrhage with brain herniation; spinal cord evaluation reveals symmetric myelin layer vacuolization and axonal degeneration involving the posterior columns and the lateral corticospinal tracts.  Which of the following is the most likely cause of this patient's spinal cord findings?

Quizplus · Accepted Answer

11ec160b_39e8_9d67_9249_8dde5119baa0_MD0001_00 This patient's history of gait dysfunction and evidence of myelin/axonal degeneration in the dorsal columns and corticospinal tract are highly suggestive of vitamin B₁₂ deficiency. Vitamin B₁₂ is an essential dietary nutrient that contributes to DNA synthesis and repair (via reduction of 5-methyltetrahydrofolate to tetrahydrofolate) and to the generation/maintenance of myelin (via methylation of neuronal lipids and proteins). Although deficiency often presents with megaloblastic anemia (due to impaired nuclear maturation of rapidly dividing hematologic cells), many patients develop neurologic manifestations due to: The spinal cord damage seen with vitamin B₁₂deficiency is called subacute combined degeneration; "combined" refers to the degeneration of ascending pathways (dorsal columns) and descending pathways (corticospinal tract). (Choice A) Amyotrophic lateral sclerosis is marked by progressive upper and lower motor neuron signs. Although damage to the lateral corticospinal tract often occurs, the dorsal columns are generally spared. Most cases present with asymmetric limb weakness, atrophy, and fasciculation due to anterior horn damage. (Choice B) Multiple sclerosis usually causes focal demyelinated plaques within the central nervous system. These are typically asymmetric and in different phases of evolution. This patient's symmetric degeneration of the dorsal columns and corticospinal tract would be unusual. (Choice C) Syringomyelia, a cyst within the spinal cord, can expand over time, leading to central spinal cord injury. The corticospinal tracts and anterior horn are often affected (eg, flaccid paralysis, atrophy). However, syringomyelia would likely be identified on gross autopsy. (Choice D) Tabes dorsalis (a form of neurosyphilis) is associated with damage to the dorsal columns and dorsal nerve roots, leading to loss of position and vibration sensation, sensory gait ataxia, and paresthesia of the extremities. However, the lateral corticospinal tracts are not generally affected. (Choice E) Thiamine deficiency causes Wernicke encephalopathy, which often manifests with gait dysfunction, confusion, and oculomotor impairment. However, histopathology generally shows demyelination in the brain (eg, mamillary bodies, thalamus, ocular motor nuclei), not corticospinal tracts and dorsal columns. (Choice F) Varicella-zoster virus infection can cause painful neuritis in the peripheral nervous system. Central nervous system lesions are less common. Educational objective: Myelopathy associated with vitamin B₁₂ deficiency is called subacute combined degeneration. "Combined" refers to myelin degeneration of both the ascending (dorsal columns) and descending (corticospinal tract) pathways. Loss of position and vibration sensation, sensory ataxia, and spastic paresis are common manifestations.

A 65-Year-Old Woman Was Found Dead in Her House