An 87-year-old woman is referred to you for evaluation of lower back pain. It is exacerbated by walking or prolonged standing and occa-sionally made better by bending over. Physical examination reveals a thin, elderly woman who walks with a cane with her lower back moderately flexed. Motor power in her lower extremities is normal, but she has impaired sensation to light touch and vibration below the L4 dermatome bilaterally. Deep tendon reflexes are normal in her upper extremities but absent in both lower extremities. You refer her for magnetic resonance imaging (MRI) of the lumbosacral spine. What will be the most likely finding on this study?