Spinal cord syndromes compared: rebuild each from three tracts
Every spinal cord syndrome is the same cross-section with a different shape of damage. Three tracts and the cord's blood supply are enough to predict each pattern.
Chapters (12)
Localise complete transection, hemisection (Brown-Séquard), central cord, anterior cord and posterior column lesions from their deficit patterns, using where each tract runs and which arteries feed the cord.
The short version
- Three tracts decide the pattern: the lateral corticospinal tract (movement) and the dorsal column (vibration and position) stay on the same side, while the spinothalamic tract (pain and temperature) carries information from the opposite side.
- One anterior spinal artery feeds the anterior two thirds of the cord with little backup; two posterior spinal arteries feed the back of the cord.
- A hemisection gives same-side weakness and loss of vibration and position, and opposite-side loss of pain and temperature.
- Central cord syndrome weakens the arms, especially the hands, more than the legs; anterior cord syndrome spares vibration and position.
- Posterior column syndrome takes vibration and position, with an unsteady gait and a positive Romberg test.
Three tracts explain the spinal cord syndromes
An older man trips and strikes his chin on the pavement. There is no fracture, but he cannot button his shirt, though he can still walk. Why are his hands worse than his legs? The spinal cord syndromes answer questions like this by asking which tracts were damaged.
Three tracts do most of the work.[1][2]
| Tract | Carries | Side in the cord |
|---|---|---|
| Lateral corticospinal tract | Movement | Same side as the muscles it controls |
| Dorsal column | Vibration and position | Uncrossed (same side) |
| Spinothalamic tract | Pain and temperature | From the opposite side |
Blood supply matters too. One anterior spinal artery feeds the anterior two thirds of the cord, with little backup.[3][7]
Two posterior spinal arteries feed the back of the cord.[7] That difference is why a vascular lesion can take the front of the cord and leave the back working.
Complete transection and spinal shock
In a complete transection, everything below the level is lost: movement, all sensation, and bladder control. Complete means nothing is spared, even in the sacral segments.[4]
At first the limbs are flaccid and areflexic, called spinal shock; as reflexes return, spasticity can follow.[4]
The syndromes that follow are incomplete: some function survives below the lesion.
Brown-Séquard syndrome: the hemisection pattern
Picture a stab wound to the right side of the mid-thoracic cord. Because each tract has its own side, the deficits split between the two legs.[2][4]
| Where | What is lost | Tract damaged |
|---|---|---|
| Below the lesion, right | Weakness that becomes spastic; loss of vibration and position | Lateral corticospinal tract and dorsal column |
| Below the lesion, left | Loss of pain and temperature, beginning about two levels down | Spinothalamic tract |
| At the level, right | Flaccid weakness and a band of lost sensation | Entering root and ventral horn |
At the level of the lesion, the findings differ from those below: lower motor neuron signs and a band of lost sensation can appear[8], because the entering root and the ventral horn can be destroyed too.
Central cord syndrome: arms worse than legs
Central cord syndrome is the opening patient. Hyperextension of a neck narrowed by spondylosis bruises the centre of the cervical cord.[4][5]
The classic teaching is that the arm fibres lie nearest the centre of the long tracts, and the central grey matter is damaged too, though newer work questions how neat that map is.[4][10]
Whatever the mechanism, the pattern is the same: the arms, especially the hands, are weaker than the legs. Bladder dysfunction is common, and the sensory loss is variable.[4][5]
Anterior cord syndrome: a vascular story
Occlude the anterior spinal artery, and the anterior two thirds of the cord dies, taking the corticospinal and spinothalamic tracts with it.[3][4]
Movement and pain and temperature are lost below the lesion, but the dorsal columns survive, so vibration and position remain.[4] Aortic aneurysm or dissection can cause it.[3]
Posterior column syndrome: tabes dorsalis and vitamin B12 deficiency
The dorsal columns are damaged in tabes dorsalis from syphilis[9], and in vitamin B12 deficiency, where the lateral corticospinal tracts are also hit.[6]
Vibration and position are lost, the gait is unsteady, and the Romberg test is positive. In a pure posterior column lesion, pain and temperature stay intact.[2][6]
Spinal cord syndromes side by side
| Syndrome | Movement | Vibration and position | Pain and temperature |
|---|---|---|---|
| Complete transection | Lost below the level | Lost | Lost |
| Brown-Séquard | Same side, below the lesion | Same side lost | Opposite side lost |
| Central cord | Arms, especially hands, weaker than legs | Variable sensory loss | Variable sensory loss |
| Anterior cord | Lost below the lesion | Preserved | Lost below the lesion |
| Posterior column | Spared in a pure lesion; lateral tracts also hit in B12 deficiency | Lost | Intact in a pure lesion |
Read the table as three questions: is movement lost, are vibration and position lost, and are pain and temperature lost? The answers rebuild each syndrome from the anatomy instead of from a memorised list.
Practice question
Original · USMLE styleA 62-year-old man is admitted with an aortic dissection. Hours later, he develops sudden back pain and cannot move his legs. Examination shows flaccid paralysis of both legs. Pain and temperature sensation are lost on both sides below the umbilicus, but vibration and joint position sense are preserved.
Common questions
What are the main spinal cord syndromes?
The lesson compares complete transection, hemisection (Brown-Séquard syndrome), central cord syndrome, anterior cord syndrome and posterior column syndrome. Each is a different pattern of damage to the same three tracts.
What are the signs of Brown-Séquard syndrome?
Below the lesion, there is same-side weakness that becomes spastic and loss of vibration and position, with opposite-side loss of pain and temperature beginning about two levels down. At the level of the lesion, there can be flaccid weakness and a band of lost sensation.
Why are the arms weaker than the legs in central cord syndrome?
The classic teaching is that the arm fibres lie nearest the centre of the long tracts, and the central grey matter is damaged too. Newer work questions how neat that map is, but the pattern of weaker arms, especially the hands, holds.
Which artery is involved in anterior cord syndrome?
The anterior spinal artery, which feeds the anterior two thirds of the cord with little backup. Its occlusion takes the corticospinal and spinothalamic tracts and spares the dorsal columns.
What causes posterior column syndrome?
Tabes dorsalis from syphilis and vitamin B12 deficiency damage the dorsal columns. In B12 deficiency, the lateral corticospinal tracts are also hit.
Transcript
Read the full narration, by chapter697 words
0:00A fall, no fracture, and weak hands
An older man trips and strikes his chin on the pavement. There is no fracture, but he cannot button his shirt, though he can still walk. Why are his hands worse than his legs? Today: compare the spinal cord syndromes by which tracts they damage.
0:16Three tracts: movement, vibration and position, pain and temperature
Three tracts do most of the work. The lateral corticospinal tract carries movement, and in the cord it sits on the same side as the muscles it controls. The dorsal column carries vibration and position, uncrossed. The spinothalamic tract carries pain and temperature, from the opposite side.
0:36Blood supply: one anterior and two posterior spinal arteries
Blood supply matters too. One anterior spinal artery feeds the anterior two thirds of the cord, with little backup. Two posterior spinal arteries feed the back of the cord.
0:48Complete transection and spinal shock
First, a complete transection. Everything below the level is lost: movement, all sensation, and bladder control. At first the limbs are flaccid and areflexic, called spinal shock, and spasticity comes later. Complete means nothing is spared, even in the sacral segments. The syndromes that follow are incomplete: some function survives below the lesion.
1:14Hemisection: Brown-Sequard syndrome
Next, a hemisection: Brown-Séquard syndrome. Picture a stab wound to the right side of the mid-thoracic cord. Below the lesion on the right: weakness that becomes spastic, and loss of vibration and position. Below the lesion on the left: loss of pain and temperature, beginning about two levels down. At the level of the lesion, on the right, the entering root and the ventral horn can be destroyed too, so there can be flaccid weakness and a band of lost sensation.
1:45Central cord syndrome
Central cord syndrome is our opening patient. Hyperextension of a neck narrowed by spondylosis bruises the centre of the cervical cord. The classic teaching is that the arm fibres lie nearest the centre of the long tracts, and the central grey matter is damaged too, though newer work questions how neat that map is. Whatever the mechanism, the pattern is the same: the arms, especially the hands, are weaker than the legs. Bladder dysfunction is common, and the sensory loss is variable.
2:17Anterior cord syndrome
Anterior cord syndrome is a vascular story. Occlude the anterior spinal artery, and the anterior two thirds of the cord dies, taking the corticospinal and spinothalamic tracts with it. Movement and pain and temperature are lost below the lesion, but the dorsal columns survive, so vibration and position remain. Aortic aneurysm or dissection can cause it.
2:41Posterior column syndrome
Last, the posterior column syndrome. The dorsal columns are damaged in tabes dorsalis from syphilis, and in vitamin B 12 deficiency, where the lateral corticospinal tracts are also hit. Vibration and position are lost, the gait is unsteady, and the Romberg test is positive; in a pure posterior column lesion, pain and temperature stay intact.
3:06Practice question
Your turn. A 62-year-old man is admitted with an aortic dissection. Hours later, he develops sudden back pain and cannot move his legs. Both legs are flaccid and paralysed. Pain and temperature are lost on both sides below the umbilicus, but vibration and joint position are preserved. Which of the following regions of the spinal cord is most likely damaged? A, both dorsal columns. B, the anterior two thirds. C, one half of the cord. D, the central grey matter. E, the whole cord cross-section. Pause here and decide.
3:50Options A, C, D and E ruled out
A is out: dorsal column damage would take vibration and position, and his are preserved. C is out: a hemisection gives weakness and lost position on one side and lost pain on the other, not symmetrical loss with the dorsal columns intact. D is out: a central cord injury is classically cervical, with the arms worse than the legs. E is out: a complete transection would also take vibration and position.
4:19The answer: the anterior two thirds
So the answer is B. The anterior spinal artery supplies the anterior two thirds, so its infarct takes the corticospinal and spinothalamic tracts and spares the dorsal columns.
4:34Recap and next lesson
Three things to keep. One: a hemisection gives same-side weakness and vibration loss, and opposite-side pain and temperature loss. Two: the central cord injury weakens the arms more than the legs; the anterior cord injury spares vibration and position. Three: the posterior column syndrome takes vibration and position, with a positive Romberg test. Next, the cranial nerve nuclei: a brainstem map.
Sources
Numbers in the text, e.g. [1], point here- OpenStax. Anatomy and Physiology 2e, 14.2 Central Processing. openstax.org/books/anatomy-and-physiology-2e/pages/14-2-central-processing
- OpenStax. Anatomy and Physiology 2e, 16.4 The Sensory and Motor Exams. openstax.org/books/anatomy-and-physiology-2e/pages/16-4-the-sensory-and-motor-exams
- Nontraumatic spinal cord injury. J Pers Med 2022. europepmc.org/article/PMC/PMC9694799
- Spinal cord injury syndromes review. europepmc.org/article/PMC/PMC8710452
- Central cord syndrome. europepmc.org/article/PMC/PMC4431046
- Cobalamin deficiency: clinical picture and radiological findings. Nutrients 2013. europepmc.org/article/PMC/PMC3847746
- Spinal cord infarction: clinical and neuroradiological clues. 2025. europepmc.org/article/PMC/PMC11856212
- Brown-Sequard syndrome secondary to cervical spinal meningioma. 2026. europepmc.org/article/PMC/PMC13589662
- Tabes dorsalis (direct invasion of the dorsal columns and roots by T. pallidum). 2025. europepmc.org/article/PMC/PMC11795238
- Macaque tracing study questioning corticospinal somatotopy in the cervical cord. 2022. europepmc.org/article/PMC/PMC10193491
The arm and leg fibre map in the central cord is classic teaching and is debated (see reference 10); the diagram says so. Tracts, vessels and lesions on screen are schematic.
The practice question is original and its patient is synthetic. Every fact is checked against the sources above in independent accuracy reviews. Always follow your local guidelines and your own laboratory’s ranges.
Image credits. Illustrations: Servier Medical Art (smart.servier.com), CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/), adapted (recoloured, outlined, cropped): spinal cord sections (thoracic and cervical), dermatome figure, elderly man. Aortic dissection icon by Kathryn Kananen (via bioicons.com), MIT licence, adapted. The tract, vessel and lesion overlays, the sketches and all handwriting are drawn in code (original).
Corrections. None so far. Spotted an error? Email info@medservatory.com with the lesson code MS-S1-NEURO-003.
For exam study only, not medical advice. Read the medical disclaimer.
In this series
Playlist on YouTube- EP 01Upper vs lower motor neuron lesions: signs and localisation5:08
- EP 02Dorsal column vs spinothalamic tract: where each pathway crosses5:01
- EP 03Spinal cord syndromes compared: rebuild each from three tracts5:06
- EP 04Cranial nerve nuclei: a brainstem map by level and position5:10
- EP 05Brainstem crossed findings: the localisation rule4:50
- EP 06Medial vs lateral medullary syndrome: artery, structures and signs5:30
- EP 07Facial nerve palsy: why the forehead tells you the lesion4:59
- EP 08Stroke syndromes by artery: ACA, MCA and PCA4:41
- EP 09Lacunar stroke syndromes: pure motor, pure sensory and more4:54
- EP 10Visual pathway lesions and field defects4:42
- EP 11Basal ganglia direct and indirect pathways: D1, D2 and movement5:19
- EP 12Cerebellar lesion localisation: vermis vs hemisphere4:42
- EP 13Brain herniation syndromes: what is squeezed, and where4:56
- EP 14CSF flow and hydrocephalus: where the flow fails5:12
- EP 15Corticospinal tract: from cortex to anterior horn4:59
- EP 16Hypothalamic nuclei and their functions5:24