This document discusses lesions of the spinal cord caused by damage to the dorsal and ventral nerve roots or incomplete transection of the spinal cord. It describes the features that result from sectioning the dorsal or ventral nerve roots, including sensory and motor loss. It then covers the stages and features of complete transection of the spinal cord - initial spinal shock and flaccidity, followed by a reflex activity stage. The features of Brown-Sequard syndrome from transverse hemisection are also outlined, including motor and sensory losses on the side of and below the lesion.

1. Lesions of the spinaL
cord
Made by
Mehreen roohi

2. • Section of the Dorsal nerve root:
• Features:
• If only one dorsal nerve root is cut, there is no
appreciable sensory loss because of the
overlapping of the adjacent dermatome.
• To have sensory loss, at least three dorsal
sensory nerve roots should be damaged.

3. • The loss of all sensation in the sensory area, if lesion of the three
dorsal nerve roots are damaged.
• (fine touch, vibration, pain, temperature, proprioception).
• When there is a section of the dorsal nerve root:
• 1) There is atonia in muscles of the affected area (reflex arc is not
completed, so atonia).
• 2) Loss of superficial and deep reflexes.
• 3) Movement of the affected part is not normal because of the loss
of the proprioceptive input to the parts of the brain which control the
movements.

4. • 2) Features due to section of the Ventral nerve root:
• Ventral root of the spinal nerve contains somatic motor fibres and
autonomic nerve fibres.
• When there is section of ventral nerve root, so both somatic and
autonomic fibres are cut, so it results in:
•
• A) Flaccid paralysis in the affected part
• B) Loss of voluntary movement
• C) Muscle tone is lost
• D) Loss of superficial and deep reflexes (damage to the somatic
motor fibres).

5. • If the lesion is in the thoracic and lumber segments
of the spinal cord.
• There is also damage to the sympathetic nerve fibres, so
in the affected part, there is:
• 1) Vasodilatation (due to loss of vasomotor tone)
• 2) Fall in peripheral resistance and blood
• pressure.
• 3) Loss of sweating in the affected part.
• So skin becomes dry in the affected part.

6. Sections of Spinal cord
• Complete transection of the spinal cord:
• Causes:
• 1) Fracture dislocation of the vertebral column
• due to stab wound or bullet wound.
• 2) Extending tumor
• 3) May be due to some accident

7. • When there is complete transection of spinal cord, we can divide features
into three stages:
• 1) Stage of Flaccidity or Spinal shock:
• Immediately after the transection below the level of transection:
•
• A) There is complete flaccid paralysis.
• B) There is loss of all sensations.
• C) Loss of all superficial and deep reflexes.
• D) There is loss of skeletal muscle tone and the smooth muscle tone.
• E) Due to loss of tone in sphincters, there is urinary and fecal incontinence.

8. • If the transection is at the level of T1 or above, there
is:
• A) Loss of vasomotor tone, which results in the fall in
peripheral resistance and blood pressure.
• B) Limbs becomes cold, blue and dry.
• C) Bed sores may appear.
• This is the stage of spinal shock and flaccidity.

9. • Cause of Spinal Shock:
• Is due to loss of tonic facilitatory effect of high centres on
Spinal cord neurons through corticospinal, reticulospinal
and vestibulospinal tracts.
• Normally higher centres got tonic effects on spinal cord
through these descending tracts, so tonic effect is
disturbed, so stage of flaccidity persists.
• This stage persists for 2-3 weeks. The spinal cord
neurons are functionless without the tonic facilitatory
effect of the higher centres on spinal cord neurons.

10. Stage of reflex activity
• Tone begins to appear first in the smooth muscles and
sphincters.
• So when tone appear in urinary sphincter, there will be
retention of urine and feces.
• Vasomotor tone also appears to come back to some
extent because spinal cord sympathetic pre-ganglionic
neurons learn to function without the facilitatory effect of
higher centres.
• So V.M tone appear to some extent. When it appears,
B.P increases, blood flow to the limbs recovered.

11. • Tone begins to appear in the skeletal muscles, first appears in the
flexors, but muscle tone is not as much as the normal because
Myotatic reflex is not normally strong in the absence of the
facilitation effects from the higher centres.
• When muscle tone appears in flexors, the legs are moderately
flexed and that is called Paraplegia in Flexion.
• Muscles contraction starts during reflex action. There may be
spontaneous involuntary contractions involving mainly the flexors.
• Flexor reflex or withdrawal reflex can be elicited.
• Flexor reflex is also accompanied by crossed extensor reflex. But
response is less than the normal.

12. • Other features:
• There is Mass-reflex or response.
• When the skin over anterior abdominal wall or on the legs is stimulated
(stretched), there is a response, which includes contractions of the anterior
abdominal wall muscle.
• Contractions of flexors in the leg.
• There is evacuation of the urinary bladder even if it contains small amount
of urine.
• This is due to increased intra-vesical pressure resulting from the contraction
of the anterior abdominal wall muscles.
Loss of sweating in affected part.

13. • In males:
• Erection can occur when there is stimulation of
the genital organs.
• Muscle tones also returns in extensors.
• After months of the transection, below the level
of lesion, there is UMN type of paralysis.
• Muscles can not contract for voluntary
movement.

14. • Sensory loss is not recovered.
• There is automatic bladder and also there is
automatic defecation because reflexes can be
activated.
• By training, in some of the patients, scratch in
the skin around thigh or anal region, defecation
and urination occurs.
• So training is done, there is no recovery
regarding the reflexes.

15. • Stage of the failure of reflex activity:
• 1) When there is some severe infarction
and toxemia, condition of the patient
becomes worse.
• 2) Different reflexes become difficult to be
elicited and intensity of stimuli required to
elicit these reflexes increased.

16. • 3) Response during these reflexes are
also decreased.
• 4) Muscle tone decreases (muscles
becomes flabby.
• 5) Bed sores appear and patient becomes
worse and worse.

17. Hemisection of Spinal cord
• Brown – Sequard Syndrome:
• The clinical condition produced by transverse
section of the right or left half of the spinal cord
is called Brown Sequard syndrome.
• Causes:
• 1) Fracture dislocation of vertebral column.
• 2) Tumors
• 3) Accidents

18. • Features in three components:
• 1) Above the section of Hemisection:
• 1) There is no motor loss on the same side
and opposite side.
• 2) There may be hyper-aesthesia
ipsilaterally due to irritation of the cut
ends of the sensory nerve fibres.
• 3) No sensory loss on the opposite side.

19. • At the level of Hemisection:
• 1) Ipsilaterally there is lower motor neuron type of
• paralysis due to damage to the ventral horn of motor
• neurons.
• (Few muscles are involved,
• Flaccid paralysis, loss of voluntary movements, hypotonia, atonia,
• Loss of superficial and deep reflexes, or tendon jerks, muscle atrophy,
• Fasciculation and fibrillation, contractures formation, reaction of
degeneration).
• 2) Ipsilaterally, there is a band of a anesthesia, loss of all sensations
• on the same side.
• 3) On the opposite side, there is no motor loss, no sensory loss.

20. Below the level of Hemisection
• 1) The muscles supplied by the segments below the
lesion will show UMN type of paralysis.
• There is UMN type of paralysis on the same side.
• For example; hypertonia, Babinki’s sign, damage due to
corticospinal and extra-corticospinal tracts.
• So UMN type of paralysis.
• Motor effects are seen on the side of the section
• 2) On the opposite side, there is no motor loss.

21. • 3) Sensory loss is ipsilaterally, fine touch, two point
discrimination, vibration and proprioception (due to
damage to dorsal column medial lemniscal system).
• 4) On the opposite side, there is loss of pain and
temperature, tickle, itch and crude touch.
• This sensory loss is 2 to 3 dermatomes below the level
of hemisection (because of oblique crossing over of
spinothalamic tracts to the opposite side).

22. • 6) Sensation carried by dorsal column are lost on
the same side.
• 7) Sensation carried by spinothalamic tract, are
lost on the opposite side.
• 8) In Brown- Sequard Syndrome:
• Concentrate on motor loss on the same side:
• Ipsilaterally motor loss is important for the patient
because there is paralysis of UMN of the same side.
• On the opposite side, there is sensory loss.
• There is predominant motor loss ipsilateraally and predominant
sensory loss on the opposite side.

23. • If hemisection involves the thoracic
segments, there will be damage to the
sympathetic system.
• So there will be decrease in peripheral
resistance, fall in B.P, loss of sweating in
affected part.

24. Incomplete Transection of the
spinal cord
• The damage to spinal cord tissue is between complete transection and
hemisection.
• Causes:
• Are same as complete transection and hemisection.
• For example; fracture dislocation of vertebral column by stab wound, tumors
and accident.
• 1) Same stages, as we discuss in complete
• transection of spinal cord.
• 2) Stage of spinal shock and stage of flacidity.
• 3) Same features of Spinal shock as in case of complete
• transection.

25. • 4) After 2-3 weeks, in stage of reflex activity, there are
some differences from the features of complete
transection.
• Differences:
• 1) Skeletal muscle tone begins to appear.
• First begins to appear in the extensors.
• (There is paraplegia in extension in incomplete
• transection of spinal cord).

26. • 2) Stage of reflex activity:
• In incomplete transection, the
vestibulospinal and reticulospinal
tracts escape damage.