Lecture 05 Clinical Aspects of the Sensory and Motor Pathways Flashcards
What does destruction of the dorsal root result in? What happens with the sacral region specifically?
Diminished motor reflexes including muscle tonicity
Sacral region: atonic bladder and painless retention of urine
What does complete unilateral lesions of the posterior columns result in?
an ipsilateral loss of proprioception, 2-pt tactile discrimination and vibratory sensations below the lvl of lesion
What does a unilateral lesion of the fasiculus gracilis result in?
ipsilateral loss of proprioception, 2-pt tactile discrimination and vibratory sensations from the lower half of the body and lower extremity
Partial lesion: sensory dermatomal deficit corresponding to affected region
What does a unilateral lesion of the fasciculus cuneatus result in?
ipsilateral loss of proprioception, 2-pt tactile discrimination and vibratory sensations from the upper half of the body and upper extremity
partial lesion: sensory dermatomal deficit corresponding to affected region
What is found in the lateral funiculus?
Lateral corticospinal tract
Lateral reticulospinal tract
What does the destruction of the LCSt and associated motor tracts in lateral funiculus result in?
spastic paralysis hyperreflexia hypertonia Babinski sign clonus disuse atrophy
What does transection of the spinal cord above S2 intterupt?
the LRST to the sacra autonomic nucleus
What does LRST interruption result in?
pt unable to voluntarily void bladder = urinary retention
After spinal Shock, bladder reflex may return w/o voluntary control, automatic reflex voiding or reflex bladder
What is found in the anterior funiculus?
Lateral spinothalamic tract
Anterior white commissure
LMN
What does unilateral lesions of the lateral spinothalamic tract result in?
contralateral loss of pain and temp sensation 2 sensory dermatomal segments BELOW the lvl of lesion
What does destruction of the anterior white commissure result in?
bilateral loss of pain and temp sensations to the upper extremities (yoke-like)
What does Destruction of LMN or axons of one or more of the cranial or spinal motor nuclei result in?
LMN paralysis: flaccid paralysis, areflexia, attonia, atrophy, and fasiculations
What are pts that are insensitive to pain missing. (congenital)
C type fibers
What does Herpes Zoster compromise?
non-nociceptive A alpha/beta fibers
C fibers take over and open gate to pain
What does unilateral lesions of the spinoreticular fibers result in?
no significatn sensory deficits
Bilateral may eliminate crude pain sensations
What is done neurosurgically to treat intractable pain?
LSTT transected
Anterolateral quadrant of the cord is cut two segments above and on the opposite side of the area of pain
What serves as a landmark between LSTT and corticospinal fibers during anterolateral cordotomy?
denticulate ligaments
What does unilateral lesions of the spinal lemniscus result in?
contralateral hemianalgeisa and thermal hemianesthesia
Syringomyelia results in the destruction of what?
anterior white commissure
lateral corticospinal tracts
anterior horns
posterior columns
What does unilateral lesions of the medial lemniscus result in?
a loss of proprioception, 2-pt tactile discrimination and vibratory sensations on the opposite side of the body and limbs
What are lightning pains or rheumatic pains from the lower limbs in pts with tabes dorsalis is probably due to what?
irritation of the type A pain fibers in the dorsal roots
What are the symptoms of LMN paralysis
Flaccid paralysis Areflexia Atonia Atrophy Fasiculations
What is flaccid paralysis?
muscle completely limp and there is no resistance to passive movement
What is areflexia?
loss of efferent component of reflex arc to a muscle results in an absence of the associated muscle reflex
What is Atonia?
Destruction of gamma motor neurons or their axons results in the absence of muscle tone
What is atrophy?
tissue waste
- denervated muscle atrophies due to loss of stimulation from the motor neurons
What are fasiculations?
twitchings of denervated muscle probably due to hypersensitivity of the motor end plate
What does poliomyelitis involve?
the motor neurons of the anterior horns and the cranial nerve motor nuclei
What are the symptoms of UMN paralysis ?
Varying degree of spastic paresis of axial and proximal limb m
Some degree of spastic paralysis of distal limb m especial upper
Hypertonia
Hyperreflexia
Babinski sign
Clonus
Disuse atrophy
What is spasticity ?
abnormal, passive resistance to movement in one direction
What is rigidity ?
abnormal passive resistance to movement in one direction
What are the three phases of physical events following UMN lesion?
- Spinal shock with areflexia, atonia, and flaccid paralysis
- wks-months: return of basic spinal reflexes, some spastic paresis of axial and prox limb mm and spastic paralysis of distal limb
- yrs: spasms of extensors, flexors or remain flaccid
Clonus, clasp-knife spasticity, babinski reflex
UMN or LMN lesion?
UMN
Hyperactive deep tendon reflexes
UMN or LMN lesion?
UMN
Hypoactive or absent deep tendon reflexes
UMN or LMN lesion?
LMN
Hypotonia
UMN or LMN lesion?
LMN
The most common form of amyotrophic lateral sclerosis (ALS) involves the combination of what structures?
LMN: anterior horn cells, hypoglossal nucleus, nucleus ambiguus, facial motor nucleus
UMN: chronic, progressive degeneration of the corticospinal tracts
What does ALS lead to?
LMN paresis and atrophy of the intrinsic mm of the hand followed later by arms and shoulder musculature
What does the involvement of the corticospinal tract with ALS lead to?
spastic paralysis, hyperreflexia and babinski sign
NO SENSORY DEFICITS
What are the 7 clinically important regions of the spinal cord?
Dorsal roots Posterior columns Lateral corticospinal tract (UMN) Lateral spinothalamic tract (pain/2pt) Anterior white commissure Anterior horn (alpha motor neurons, LMN) Lateral reticulospinal tract
