Nervous System Lesions: Segmental vs. vertical

Question 1

Segmental organization: what are segments

Answer 1

• identified by the same designation as their corresponding spinal nerves
• a segmental lesions = problems with function at that level of spinal cord

Question 2

Dorsal rhizotomy

Answer 2

• cutting of selected roots is a treatment for muscle overativity in spastic CP

Question 3

Dermatomes and their relation to segmental lesions

Answer 3

• dermatome is an area of skin innervated by axons from cell bodies in a single dorsal root
• segmental lesions will follow a dermatome

Question 4

Describe how axons are entering the spinal cord based on what information they carry

Answer 4

• axons carrying information from touch and proprioception enters medially through 1A and A beta
• axons carrying information about tissue damage or threat to tissue damage and temperature enter the cord laterally

Question 5

Spinal organization and spinal nerves

how are the regions named

Answer 5

• cervical region spinal nerves are found above the corresponding vertebra
• exception is 8th spinal nerve emerges between C7 and T1
• remainder of the spinal cord = spinal nerves lie below the corresponding vertebrae
• spinal cord ends at L1-2 vertebrae spaces
• L2-5 nerve roots ravel downward below the end of the spinal cord before exiting as the cauda equina

Question 6

Segmental lesions

presentation

Answer 6

• produces loss of sensation from dermatome and myotome
• sensory and motor will be interrupted

Question 7

Sensory signs of segmental dysfunction

Answer 7

• imparied sensation = paresthesia

OR

• loss of sensation = anesthesa
• in a dermatomal pattern

Question 8

Motor signs of segmental dysfunction

Answer 8

• LMN signs
• atrophy
• flaccid weakness
• fasciculations = quick twitch seen below skin
• fibrillations = brief contraction of motor unit that cannot be seen nder skin
• reflexes are absent if either the motor OR sensory fibers in the circuit are damaged

Question 9

Segmental pain control/gait control theory

Answer 9

• feel the need to touch a painful area
• when you add pressure = mechanoreceptors are stimulated
• goes to an interneuron to release enkephalin
• enkephalin inhibits/dampens pain signals

Question 10

Segmental lesion exmaples/: radiculopathy

Answer 10

• lesion of dorsal or ventral nerve root
• produces pain in the innervated dermatome and weakness in the muscles innervated by the spinal cord segment
• herniated disc, tumor, dislocated fracture

Question 11

How can a dorsal or ventral root lesion occur

Answer 11

• infection
• avulsion severence

Question 12

Avulsion severence

Answer 12

• complete severenace of dorsal root that produces pain in the innervated deramtome
• Erbs palsy (C5-C6)
• Klumpke’s palsy (C8-T1
• if ventral root deprives muscle innervation and results in atrophy and fibrillation

Question 13

Erbs palsy

Answer 13

• C5-C6
• forceful seperation of head and shoulder
• lost Abduction, ER, elbow flexion
• bicep and brachioradilis reflex lost

Question 14

Klumpke’s paralysis

Answer 14

• C8-T1
• claw hand
• traction of Abducted arm
• hand intrinscics, long finger flexors and extensors

Question 15

Dorsal root ganglion lesion s

Answer 15

• more sensitive to mechanical change than proximal or distal axons of primary nociceptive afferents
• DRG develop action potentials in response to mechanical stimulation that are preceived as pain in the perheral axon +hyperalgesia
• EX: sciatica
• infection of DRG from herpes zoster/shingles = dermatome rash

Question 16

Vertical tracts lesions

What are they and what can be expected to happen

Answer 16

• tracts between brain and spinal cord
• stroke, spinal cord injury, abdnormal development, neurodegenerative disorders, anoxic brain injury, traumatic brain injury, tumor, infections, inflammatory disorders and metabolic disorders
• results in a loss of function below the level of the lesion
• signs may be Ipslateral, contralateral, or bilateral
• UMN signs and sensory changes/loss
• ANS signs = BP regulation, sweating, bowel/bladder control

Question 17

What occurs with reflexes in segmental dysfunction

Answer 17

• decreased/absent with LMN
• hyperreflexia if it is within the spinal cord

Question 18

Compare segmental vs vertical function

Answer 18

• segmental function = spinal cord (roots and spinal nerves)
• VERTICAL FUNCTION: SPINAL CORD/CNS
• Extent of loss depends on area of spinal cord or CNS involved
• segmetnal and vertical signs can occur together