SCI Flashcards
damage in motor system results w/ inability to regulate muscle tone by 2 ways…
- hypotonia
2. hypertonia (spastic and rigid)
3 causes of hypotonicity
- cerebellar disorders
- lower motoneuron lesion
- (temporary) following an acute upper motor lesion
2 causes of hypertonicity
- chronic motorneuron lesions
2. some basal ganglia disorders
SCI… what happens
above level of injury
at level of injury
below level of injury
- above = normal
- at = hypotonicity = flacid
- below = hypertonicity
lower motorneuron disorders
what LMNs do
if cell body or axon is destroyed…
this leads to (4)
- lower motoneuron innervate muscle fibers:
- if cell body or axon is destroyed this causes interruption of signals => prevents muscle contractions
this leads to: - loss of reflexes
- atrophy
- flaccid paralysis
- fibrilations (rapid, uncoordinated mm contraction)
upper motor neutrons definition
- neurons whose axons descend from the cerebrum and brain stem to synapses on lower motor neurons (alpha and gamma)
4 things upper motor neuron lesions cause
- abnormal cutaneous reflexes (eg babinskis sign)
- abnormal timing of muscle activation
- paresis or paralysis- inadequate recruitment of lower motor neuron
- spasticity- velocity dependent muscle hypertonia
4 examples of abnormal timing of muscle activation (and what type of lesion causes these)
from upper motor neuron lesion
- initiation of movement is delayed
- rate of force development is slowed
- muscle contraction is prolonges
- activation of antagonist is disrupted
3 types upper motor neuron lesions
- SCI
- stroke
- congenital
2 criteria SCI are classified by
- complete or incomplete
2. neurological level of injury (dermatomes and myotomes)
how (1) neurologists and (2) physiatrists define level of injury
- neurologists define level of injury as first spinal segmental level that shows loss
- physiatrists or rehab drs tend to define level of injury as lowest spinal segment level that is normal
3 things lesion of SC may interfere with…
- segmental function
- vertical tract function (interruption of pathways receptors, muscles/ cortex)
- both segmental and vertical tract
segmental lesions interfere with…
if affect dorsal roots/ dorsal horn
ventral roots/ ventral horn
- neural function only at level of lesion, (ie-affects myotome and dermotome at level of lesion)
- if they involve dorsal roots and dorsal horn = sensory function
- ventral roots/ ventral horns = flaccid weakness, atrophy, fibrillation/ fasciculation and hyporeflexia
signs of descending tract vertical dysfunctions (4)
- paralysis
- hyperreflexia
- hypertonia
- babinskis sign
complete injury
def
2 examples
- total and permanent function disruption of SC with no sensory or voluntary motor function in areas innervated more than 3 segments below level of injury
eg- tetrapelgia (c-spine level)
parapelgia (below c-spine-spares amrms)
incomplete injury
- incomplete disruption => some ascending and descending fibers still intact (so minimal sensation and some voluntary motor function) more than 3 segments below
hemisection (brown-sequard syndrome)
def
what is causes on ipsilateral and contralateral side
damage to one side causing:
- ipsilateral motor paralysis and loss of proprioception
- contralateral loss of pain and temp
anterior cord syndrome from trauma to... results in what is still intact? superlative
- trauma to anterior cord or anterior spinal artery AND interruption of anterior and lateral spinothalamic tract
- bilateral loss of… pain, temp and movement
- can still feel position, vibration and touch
- worst prognosis of all cord syndromes
central cord syndrome
cause
results in
- incomplete injury from hyperextension or OA
2. greater loss of motor function of upper fibers because they are more medial
cauda equina syndrome (2)
- damage to lumbar and/or sacral nerve roots due to massive central disc herniation
- causes flaccid paralysis of lower limb muscles, bladder and bowels
charcot-marie-toth disease process (and type of neuropathy) when do symptoms begin what is initial symptom
- hereditary motor and sensory peripheral nervous system neuropathy characterized by progressive loss of muscle tissue and touch sensation across various body party
- symptoms begin in late childhood or early adulthood. some people do not experience symptoms until their early 30s or 40s.
- initial symptom is foot drop
ipsilateral vs. contralateral dysfunction (which tract is affected)
- ipsilateral = dorsal column
2. contralateral = spinothalamic tract
