2 - Spinal Cord

Pia mater

innermost

Arachnoid mater

outside pia mater

• Subarachnoid space – contains cerebrospinal fluid

Dura mater

outermost layer, sturdy layer of connective tissue that has lots of sensory nerve endings

Cauda Equina

Area distal to L1 where the lumbar and sacral nerves roots run inferiorly within the spinal canal - considered PNS

What type of injuries occurs when the spine is injured at L1/L2 or lower?

LMN injuries: flaccid paralysis, atrophy, hyporeflexia

Saddle anesthesia

Sensory impairment in perineal and inner thigh area

• Red flag for cauda equina syndrome

• Requires immediate referral

Grey matter

Composed of neuron cell bodies and dendrites

• Includes: dorsal, lateral, and ventral horns

Dorsal horn

Contains sensory (afferent) nerve fibers

Lateral horn

Contains cell bodies of autonomic neurons

• Only found in T1 – L2 and S2 – S4

Ventral horn

Contains cell bodies of motor neurons (LMNs) that innervate skeletal muscles

White matter

Contains both ascending and descending tracts

Ascending tracts

carry action potentials to the brain

Descending tracts

carry signals from the brain to the body

Babinski reflex test

• Performed by running a blunt object along the lateral border of the foot.

• Positive test: Great toe extends and possible splaying of other toes. Normal in infants. Sign of UMN lesion in adults

• Negative Test: Toes will flex. Normal for adults

Anterior spinal artery

supplies the anterior 2/3 of the spinal cord

Posterior spinal arteries 

– supply the posterior 1/3

Segmental arteries

supply the related spinal cord segment

Spinal shock

Period following the spinal cord injury in which there is no sensation or movement below the injured spinal cord segment. Reflexes and bowel/bladder control are typically lost. As the swelling decreases, some function may return

Quadriplegia (tetraplegia)

motor impairment to all 4 limbs

Paraplegia 

motor impairment to the lower extremities only

Hemiplegia

motor impairment to one side of the body

Monoplegia

motor impairment to one limb

Complete spinal cord injury

Complete paralysis and a complete loss of sensation below the level of injury

Incomplete spinal cord injury

Any motor or sensation remains intact below the level of the lesion

• Includes sacral sparing (ability to contract anal sphincter)

Physical lesion “above” the level 

Sensation, movement, and tone are normal

Physical lesion “at” the level 

• Sensation: Lost (sensory neurons going to dorsal horn destroyed)

• Movement: Paralyzed (Lower motor neurons destroyed)

• Tone: Hypotonic flaccid paralysis (Damage of LMN)

Physical lesion “below” the level

• Sensation: Lost (ascending tracts to carry info destroyed)

• Movement: Paralyzed (descending pathways can’t transmit signals past lesion)

• Tone: Hypertonic (Damage of UMN)

C1-C4

• Structures: Neck Muscles

• Functional effect: Neck stability and mobility

• Effect of injury: Loss of neck stability

C3-C5

• Structures: Diaphragm

• Functional effect: Breathing

• Effect of injury: Ventilator dependent

C5-T1

• Structures: Upper Extremity

• Functional effect: Upper extremity movement

• Effect of injury: Tetraplegia

T1-L5

• Structures: Trunk muscles Intercostals Abdominal wall muscles

• Functional effect: Trunk stability and movement Accessory respiratory muscles 

• Effect of injury: Loss of trunk stability Decreased respiratory function

L2-S4

• Structures: Lower extremity

• Functional effect: Lower extremity movement

• Effect of injury: Paraplegia

S2-S4

• Structures: Pelvis, diaphragm, genitals

• Functional effect: Sphincter control (bladder and bowel) Sexual function

• Effect of injury: Neurogenic bladder/bowel Loss of sexual function

Asia Impairment Scale (AIS): A rating

Complete. No sensory or motor function is preserved in the sacral segments S 4-5.

Asia Impairment Scale (AIS): B rating

Sensory Incomplete. Sensory, but not motor function is preserved below the neurological level and includes the sacral segments S 4-5 AND no motor function is preserved more than three levels below the motor level on either side of the body.

Asia Impairment Scale (AIS): C rating

Motor Incomplete. Motor function is preserved at the most caudal sacral segments for voluntary contraction OR meets the criteria for sensory incomplete status and has some sparing of motor function more than three levels below the ipsilateral motor level on either side.

Asia Impairment Scale (AIS): D rating

Motor Incomplete. Motor incomplete status as described above with at least half of key muscle functions below the single NLI having a muscle grade of at least 3/5

Asia Impairment Scale (AIS): E rating

Normal

Brown-Sequard Syndrome

• At the level: Ipsilateral flaccid paralysis and sensory loss (dorsal horn fibers cut)

• Below the level:

  • Ipsilateral spastic paralysis and loss of proprioception, vibration and 2-point discrimination (dorsal columns cut)

  • Contralateral loss of pain and temperature (lateral spinothalamic)

Central cord syndrome 

• Typically caused by damage to the center of the spinal cord by traumatic bending of the cervical spine

• Symptoms:

  • UE mm flaccid paralysis - on the corticospinal tract and spinothalamic tract ) the portion related to the a UE is more medial than the LE and is therefore ore affected)

  • UE sensory loss

Anterior Cord Syndrome 

Damage to the anterior part of the spinal cord; posterior white matter spared. Caused by traumatic bending of the cord or conditions that narrow that spinal canal

• Symptoms:

  • Conscious proprioception, vibration and 2- point discriminative touch remains intact

  • Loss of motor function below lesion

  • Loss of pain and temperature below lesion

Cauda Equina Syndrome

Damage occurs below L1 Considered to be a PNS (LMN) injury (to the dorsal and ventral nerve roots)

• Symptoms:

  • Flaccidity

  • Loss of sensation

  • Areflexia

  • Impairment of bowel and bladder function