Spinal Cord Tracts

A 58-year-old Indian male presents with progressive difficulty walking, positive Romberg sign, and loss of vibration sense in both lower limbs. Serum B12 level is 180 pg/mL (normal >200). MRI spine shows T2 hyperintensity in the dorsal midline of the cervical and thoracic cord. The structure marked **B** in the diagram is primarily affected in this condition. Which of the following best explains the clinical presentation?

A 52-year-old man from Delhi presents with a 3-month history of progressive weakness in both lower limbs with spasticity. On examination, he has hyperreflexia and bilateral Babinski sign. Vibration and proprioception are intact, but he has loss of pain and temperature sensation below the level of T6 dermatome bilaterally. Gait is stiff and scissor-like. MRI spine shows a central cord lesion at T5–T6 with syrinx formation. Which spinal tract is most likely damaged to explain the dissociated sensory loss?

A 68-year-old woman from Mumbai presents with acute-onset right-sided weakness and loss of pain sensation on the left side of her body below the level of T10. Vibration and proprioception are normal bilaterally. Examination shows right lower limb hyperreflexia and Babinski sign, but left lower limb reflexes are normal. MRI spine shows an acute infarct in the right anterior spinal artery territory at T10. Which combination of tracts is damaged?

A lesion at the T5 spinal cord level on the right side results in loss of pain and temperature sensation on the left side starting 2–3 segments below the lesion. Which tract is damaged?

A 34-year-old woman from Bangalore presents with progressive weakness of both lower limbs over 3 weeks, with preserved pain and temperature sensation but loss of vibration sense and proprioception in the feet bilaterally. Examination shows hyperreflexia, positive Romberg sign, and a sensory level at T8. MRI shows a T2-hyperintense lesion in the dorsal columns spanning T6–T10. What is the most appropriate next step in management?