The preferred treatment for this patient is: A 48-year-old male with 2 years of progressive weakness in both lower limbs and 3 months of difficulty urinating and constipation. Examination: muscle strength III in both lower limbs, hyperactive knee and ankle reflexes, positive bilateral Babinski signs, positive bilateral Chaddock signs, hypoesthesia below the T8 level. Lumbar puncture: elevated cerebrospinal fluid protein. Queckenstedt test showing complete spinal canal obstruction. MRI showing an intraspinal mass-like soft-tissue lesion with spinal cord compression.