A 58-year-old strict vegetarian with type 2 diabetes on metformin for 9 years has tingling in both feet and unsteadiness that worsens in the dark. Romberg test is positive; vibration and joint position sense are lost in the legs; knee jerks are brisk, ankle jerks absent and plantars extensor. Hb is 9.4 g/dL with MCV 114 fL. Which tracts are mainly affected?

Dorsal columns and lateral corticospinal tracts

Spinothalamic tracts and dorsal columns

Anterior horn cells and corticospinal tracts

Crossing spinothalamic fibres in the commissure

A 23-year-old hostel student who has inhaled nitrous oxide from cream-charger cartridges at parties for months now has tingling in his feet and an unsteady gait that is worse in the dark. Vibration sense is absent at the toes, Romberg's test is positive, and both plantars are extensor. Serum B12 is low-normal, but homocysteine and methylmalonic acid are raised. How does nitrous oxide cause this?

It oxidises the cobalt in vitamin B12

It destroys the gastric parietal cells

It inhibits dihydrofolate reductase

It blocks B12 uptake in the ileum

A 40-year-old woman has had progressive weakness of both legs for a year. MRI shows an intramedullary tumour of the thoracic cord at T6. Pain and temperature sensation is reduced over both legs and the lower trunk, but sensation around the anus and perineum is normal. Why is perianal sensation spared?

Sacral fibres lie most laterally in the spinothalamic tract

Sacral segments lie in the cauda equina, below the tumour

Sacral fibres lie most medially in the spinothalamic tract

Sacral sensation travels only in the dorsal columns

Spinal cord tracts and lesions

16 NEET-PG practice questions on Spinal cord tracts and lesions, part of Anatomy. The first 16 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
A 58-year-old strict vegetarian with type 2 diabetes on metformin for 9 years has tingling in both feet and unsteadiness that worsens in the dark. Romberg test is positive; vibration and joint position sense are lost in the legs; knee jerks are brisk, ankle jerks absent and plantars extensor. Hb is 9.4 g/dL with MCV 114 fL. Which tracts are mainly affected?
1. ASpinothalamic tracts and dorsal columns
2. BAnterior horn cells and corticospinal tracts
3. CDorsal columns and lateral corticospinal tracts
4. DCrossing spinothalamic fibres in the commissure
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Answer: C · Dorsal columns and lateral corticospinal tracts
Macrocytic anaemia in a vegetarian on long-term metformin (which reduces B12 absorption in the ileum) points to vitamin B12 deficiency, and the neurology is subacute combined degeneration. Loss of myelin in the dorsal columns removes vibration and position sense (sensory ataxia, positive Romberg), and lateral corticospinal involvement gives extensor plantars and brisk knee jerks. The coexisting peripheral neuropathy explains the absent ankle jerks. Treat with parenteral B12 promptly; folate alone can worsen the neurology.
- A: Pain and temperature are not described as lost; the spinothalamic tracts are spared.
- B: Anterior horn involvement (as in motor neuron disease) gives wasting and fasciculation with no sensory loss.
- D: Commissural damage (syringomyelia) gives cape-like loss of pain and temperature.
Question 2 · Medium
A 23-year-old hostel student who has inhaled nitrous oxide from cream-charger cartridges at parties for months now has tingling in his feet and an unsteady gait that is worse in the dark. Vibration sense is absent at the toes, Romberg's test is positive, and both plantars are extensor. Serum B12 is low-normal, but homocysteine and methylmalonic acid are raised. How does nitrous oxide cause this?
1. AIt destroys the gastric parietal cells
2. BIt inhibits dihydrofolate reductase
3. CIt blocks B12 uptake in the ileum
4. DIt oxidises the cobalt in vitamin B12
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Answer: D · It oxidises the cobalt in vitamin B12
Recreational nitrous oxide oxidises the cobalt atom of cobalamin and inactivates it, so methionine synthase cannot work even when the measured B12 level looks normal. Functional B12 deficiency is shown by raised homocysteine and methylmalonic acid. The result is subacute combined degeneration, with demyelination of the dorsal columns (sensory ataxia, positive Romberg) and lateral corticospinal tracts (extensor plantars). Treatment is to stop nitrous oxide and give parenteral vitamin B12.
- A: Loss of parietal cells is the mechanism of pernicious anaemia, not of nitrous oxide toxicity.
- B: Dihydrofolate reductase is inhibited by methotrexate and trimethoprim, not nitrous oxide.
- C: Nitrous oxide does not affect ileal absorption; it inactivates B12 already in the body.
Question 3 · Medium
A 72-year-old man with known cervical spondylosis trips and falls forward onto his face. X-ray of the cervical spine shows no fracture or dislocation. He has marked weakness of both arms and hands with much milder weakness of both legs, and he has retention of urine. Which spinal cord syndrome is this?
1. ABrown-Sequard syndrome
2. BPosterior cord syndrome
3. CCentral cord syndrome
4. DAnterior cord syndrome
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Answer: C · Central cord syndrome
A hyperextension injury in an elderly man with a narrowed, spondylotic cervical canal typically causes central cord syndrome. The cord is pinched between osteophytes in front and the buckled ligamentum flavum behind, damaging the central grey matter and nearby tracts. Weakness is greater in the arms, especially the hands, than in the legs, with variable sensory loss and bladder dysfunction. MRI shows the cord injury, and many patients recover leg function first.
- A: Brown-Sequard syndrome is a one-sided weakness with crossed sensory loss.
- B: Posterior cord syndrome causes loss of position sense with preserved power.
- D: Anterior cord syndrome gives paraplegia or quadriplegia with dissociated sensory loss, legs as much as arms.
Question 4 · Medium
A 55-year-old woman with pernicious anaemia has numb feet, a positive Romberg test and stiff legs with extensor plantars. Consider four structures: 1. Fasciculus gracilis. 2. Lateral corticospinal tract. 3. Lateral spinothalamic tract. 4. Anterior horn cells. Which are mainly affected by the spinal cord lesion in her condition?
1. A2 and 4 only
2. B1 and 2 only
3. C1, 2 and 4 only
4. D1 and 3 only
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Answer: B · 1 and 2 only
Statements 1 and 2 are correct. Subacute combined degeneration from vitamin B12 deficiency 'combines' degeneration of the dorsal columns (sensory ataxia, loss of vibration and position sense) and the lateral columns, chiefly the corticospinal tracts (spastic weakness, extensor plantars). The spinothalamic tracts and anterior horn cells are relatively spared. A coexisting peripheral neuropathy explains why ankle jerks may be lost despite extensor plantars.
- A: Adds anterior horn cells and omits the dorsal columns, which are always involved.
- C: Adds anterior horn cells, which are relatively spared.
- D: Adds the spinothalamic tract and omits the corticospinal tract, which causes the spasticity.
Question 5 · Medium
A 40-year-old woman has had progressive weakness of both legs for a year. MRI shows an intramedullary tumour of the thoracic cord at T6. Pain and temperature sensation is reduced over both legs and the lower trunk, but sensation around the anus and perineum is normal. Why is perianal sensation spared?
1. ASacral fibres lie most laterally in the spinothalamic tract
2. BSacral segments lie in the cauda equina, below the tumour
3. CSacral fibres lie most medially in the spinothalamic tract
4. DSacral sensation travels only in the dorsal columns
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Answer: A · Sacral fibres lie most laterally in the spinothalamic tract
The spinothalamic tract is laminated: fibres that join it lower down are pushed outwards by those entering above, so sacral fibres lie most laterally and cervical fibres most medially. An intramedullary tumour expands from the centre outwards and reaches the sacral fibres last, giving sacral sparing. An extramedullary tumour pressing from outside tends to affect the sacral fibres early. Sacral sparing is therefore a pointer to an intramedullary lesion.
- B: Sacral sensory fibres must still ascend past T6 in the cord to reach the brain.
- C: Medial sacral fibres would be affected early by a central tumour.
- D: Pain and temperature from the sacral area travel in the spinothalamic tract, not only the dorsal columns.
Question 6 · Medium
A 19-year-old is brought to casualty after diving into a shallow village pond. He has complete paralysis of all four limbs with flaccid tone and absent reflexes, and no sensation below the clavicles. The team must wait before deciding whether the injury is complete. Return of which finding usually marks the end of spinal shock?
1. AKnee jerk
2. BVoluntary toe movement
3. CPinprick sensation in the feet
4. DBulbocavernosus reflex
Answer and explanation in LearnFree account
Question 7 · Medium
A 60-year-old man with neck pain and stiff legs is examined. When the lower end of his radius is tapped, there is no supination of the forearm, but his fingers flex briskly. The triceps jerk and both knee jerks are brisk, and both plantars are extensor. At which level is his cord compressed?
1. AC7-C8
2. BT1-T2
3. CC5-C6
4. DC3-C4
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Question 8 · Hard
A 27-year-old man was stabbed in the back on the left side. Two days later his left leg is weak with a brisk knee jerk and an extensor plantar, and he has lost vibration and joint position sense in the left leg. Pain and temperature sensation is lost on the right side from the T10 dermatome downwards. Where is the cord lesion?
1. ALeft half of the cord at about T8-T9
2. BLeft half of the cord at about T11-T12
3. CRight half of the cord at about T8-T9
4. DRight half of the cord at about T11-T12
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Question 9 · Medium
A 38-year-old tailor has many healed, painless cuts on his fingers from needles and scissors, and a swollen, unstable but painless right shoulder. Pain and temperature sensation is lost over both shoulders, arms and upper chest in a cape-like area, while light touch, vibration and joint position sense are normal. Damage to which part of the cord explains this?
1. AAnterior white commissure
2. BAnterior horn cells
3. CDorsal root ganglia
4. DDorsal columns
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Question 10 · Easy
A 35-year-old woman has a meningioma compressing the right half of her thoracic spinal cord. Which sensory finding is expected in her right leg?
1. ANormal sensation in all forms
2. BLoss of all forms of sensation
3. CLoss of pain and temperature sense
4. DLoss of vibration and position sense
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Question 11 · Hard
A 46-year-old man had a long segment of terminal ileum resected for intestinal tuberculosis with stricture 5 years ago. He now has numb feet, an unsteady gait in the dark, absent vibration sense at the ankles, brisk knee jerks, absent ankle jerks and extensor plantars. His Hb is 9.2 g/dL with an MCV of 112 fL. A local doctor started folic acid alone 2 months ago; his Hb has improved but his walking is worse. What is the next best step?
1. AIntramuscular vitamin B12 injections
2. BHigher-dose oral folic acid
3. COral pyridoxine
4. DIntravenous thiamine
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Question 12 · Easy
Fibres carrying pain and temperature from the left leg ascend in which tract?
1. ARight fasciculus gracilis
2. BLeft fasciculus gracilis
3. CLeft lateral spinothalamic tract
4. DRight lateral spinothalamic tract
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Question 13 · Medium
A 58-year-old man has had progressive weakness for 8 months. He has wasting and fasciculations of the hands and tongue, yet his reflexes are brisk and his plantars are extensor. Sensation is normal everywhere and bladder control is intact. Which two structures are degenerating?
1. ADorsal columns and corticospinal tracts
2. BAnterior horn cells and dorsal root ganglia
3. CSpinothalamic tracts and anterior horn cells
4. DAnterior horn cells and corticospinal tracts
Answer and explanation in LearnFree account
Question 14 · Medium
A 56-year-old man has had stabbing pains in his legs for a year and now walks with a wide-based, stamping gait that is worse in the dark. Romberg's test is positive, knee and ankle jerks are absent, and both pupils are small and irregular, reacting to near effort but not to light. Serum TPHA is positive. Which part of the nervous system is mainly affected?
1. ALateral corticospinal tracts
2. BAnterior horn cells
3. CDorsal roots and dorsal columns
4. DAnterior white commissure
Answer and explanation in LearnFree account
Question 15 · Easy
A 68-year-old man wakes after open repair of a thoracoabdominal aortic aneurysm unable to move his legs. Pain and temperature sensation is lost below the umbilicus, but he can feel a tuning fork on his toes and knows their position. Interrupted blood flow in which artery best explains this?
1. APosterior spinal arteries
2. BAnterior choroidal artery
3. CGreat anterior radiculomedullary artery
4. DVertebral artery
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Question 16 · Medium
A 28-year-old woman with a Chiari I malformation has a cervical syrinx from C4 to T1 on MRI. Her neurologist lists four findings it may explain: 1. Loss of pain and temperature over both shoulders and arms. 2. Preserved light touch in the same area. 3. Wasting of the small muscles of the hands. 4. Loss of vibration sense in both feet as an early sign. Which are expected?
1. A1 and 3 only
2. B1, 2 and 3 only
3. C2, 3 and 4 only
4. D1 and 4 only
Answer and explanation in LearnFree account

Spinal cord tracts and lesions

A 60-year-old man with neck pain and stiff legs is examined. When the lower end of his radius is tapped, there is no supination of the forearm, but his fingers flex briskly. The triceps jerk and both knee jerks are brisk, and both plantars are extensor. At which level is his cord compressed?

A 35-year-old woman has a meningioma compressing the right half of her thoracic spinal cord. Which sensory finding is expected in her right leg?

Fibres carrying pain and temperature from the left leg ascend in which tract?

A 58-year-old man has had progressive weakness for 8 months. He has wasting and fasciculations of the hands and tongue, yet his reflexes are brisk and his plantars are extensor. Sensation is normal everywhere and bladder control is intact. Which two structures are degenerating?

A 68-year-old man wakes after open repair of a thoracoabdominal aortic aneurysm unable to move his legs. Pain and temperature sensation is lost below the umbilicus, but he can feel a tuning fork on his toes and knows their position. Interrupted blood flow in which artery best explains this?