Clinical Aspects Of Sensory And Motor Pathways Flashcards
What does a unilateral lesion of fasiculus gracilis result in?
Ipsilateral loss of proprioception, 2 pt tactile discrimination and vibratory sensations form lower half of body and lower extremity
Partial lesions result in sensory dermatomal deficit corresponding to affected region of fasciculus gracilis
What does a unilateral lesion of the fasciculus cuneatus result in?
Ipsilateral loss of proprioception, 2-pt tactile discrimination and vibratory sensations from upper half of body and upper extremity
Partial lesions result in sensory dermatomal deficit corresponding to affected region of fasciculus cuneatus
What does destruction of the lateral corticospinal tracts (LCST) and associated motor tracts in lateral funiculus result in?
Spastic paralysis, hyperreflexia, hypertonia, Babinski sign, clonus, and disuse atrophy
Transection of the spinal cord above S2 interrupts the lateral reticulospinal tract (LRST) to sacral autonomic nucleus. Whatis the result?
Patient is unable to voluntarily void his bladder (urinary retention)
After spinal shock, bladder reflex may return without voluntary control, and the patient will have automatic reflex voiding or a reflex bladder
What does a unilateral lesion of the lateral spinothalamic tract (LSTT) result in?
Contralateral loss of pain and temperature sensation two sensory dermatomal segments below the level of the lesion
What does the destruction of the anterior white commissure result in?
Bilateral loss of pain and temperature sensations to upper extremities (“yolk-like” anesthesia)
Describe lower motor neuron paralysis
Results from destruction of motor neurons or axons of one or more cranial or spinal motor nuclei.
LMN paralysis is characterized by flaccid paralysis, areflexia, atonia, atrophy, and fasciculuations
Describe congenital absence of C type fibers
Allows nonnociceptive fibers (A alpha/beta) to “close” the gate
Person is insensitive to pain
Describe herpes zoster (shingles)
Infection may compromise nonnociceptive A alpha/beta fibers, allowing nociceptive C fibers to “open” the gate
Person has increased sensitivity to pain from sensory dermatome of affected nerve
What do unilateral lesions of the spinoreticular fibers result in?
No significant sensory deficits
Indirect spinothalamic pathway is too bilatearl and diffuse to be affected by unilateral lesions
Describe anterolateral cordotomy
Neurosurgically, the LSTT may be transected for relief of intractable pain
The anterolateral quadrant of the cord is cut two segments above and on opposite side of area of pain
Denticulate ligaments serve as landmarks between LSTT (anteriorly) and corticospinal fibers (posteriorly)
Crude pain sensations usually remain intact or are only temporarily diminished
What do unilateral lesions of the spinal lemniscus result in?
Contralateral hemianalgesia and thermal hemianesthesia
What is syringomyelia?
Gross cavitation and gliosis of central canal usually occurring in cervical regions of spinal cord
As the syrinx enlarges, the neurological deficits progressively worsen over a period of months or years
May occur secondary to central cord syndrome
CCS results in abrupt onset of neuro deficits
What does enlargement of a syrinx result in?
Destruction of anterior white commissure with a bilateral loss of pain and temperature sensations to upper extremities (“yoke-like” anesthesia)
Asymmetrical (unilateral or bilateral) destruction of lateral corticospinal tracts results in spastic paralysis, hyperreflexia, hypertonia of LE
Anterior horns may be destroyed unilaterally or bilaterally, resulting in LMN paralysis (flaccid paralysis, atrophy, arelexia, atonia) of upper limb
Some part of posterior columns may also be affected and result in ipsilateral anesthesia (proprioception and 2-pt tactile) below level of lesion
Describe unilateral lesions of ventral spinothalamic pathway (VSTT)
May be difficult to lose crude touch sensations because fibers ascend in both primary and anterolateral funiculi
