Spinal Injury Case Study

Is this a total or partial transection? If partial, which side is the lesion on?
right-sided partial transection. Patient exhibited right-sided weakness and loss of proprioception, and loss of pain and temperature on the left side = right-sided partial transection

(same side) upper motor neuron paralysis and loss of proprioception (touch, position, vibratory sensation)

(opposite side) loss of pain and temperature sensation

Which tracts are severed that result in loss of voluntary motor function?
Corticospinal tract -Transmits motor axons from the cerebral cortex to the synapses in the spine that control contralateral voluntary motor function. Corticospinal tract lesions cause upper motor neuron dysfunction
Interruption of the lateral corticospinal tracts, the lateral spinal thalamic tract (and occasionally the posterior columns) produces a presentation of one spastic, weak leg with brisk reflexes and a strong leg with loss of pain and temperature sensation.

Motor neuron
neuron that stems off from the spinal cord, projects its axons outside of the spinal cord and controls muscles directly or indirectly

Upper motor neurons (UMNs)
originate in the motor region of the brain stem
Work through glutamate, a neurotransmitter than transmits nerve impulses from the UMNs to LMNs, where it is detected by glutamergic receptors

Lower motor neurons (LMNs)
receive impulses from UMNs, connect the spinal cord and brain stem to muscle fibers

Signs of upper motor neuron damage
Muscle spasticity (stiffness and resistance to movement); Brisk reflexes; Babinski sign (reflex, sign of damage to the nerve paths connecting the brain to the spinal cord)

Signs of lower motor neuron damage
Weakness ; Muscle atrophy (wasting); Fasciculations (muscle twitching)

Which tracts are severed that result in loss of proprioception?
Proprioception is the body’s sense of movement and place that is independent from vision. When there is a loss of proprioception the tract that is lost is the lateral corticospinal tract, which is a major pyramidal tract in the spinal cord that controls movement of the ipsilateral limbs

Are these tracts ipsilateral or contralateral?
To determine if something is ipsilateral or contralateral it depends on whether the afferent pathway is damaged above or below the site of the damage. If it is damage is below the site of damage then it is known as ipsilateral or on the same side. If there is damage above the site of the afferent pathway the loss is known as contralateral or on the opposite side.
The lateral corticospinal tract is a descending pathway making this relevant to the lower parts of the body, her loss would be ipsilateral.

Which tracts are severed that result in loss of pain and temperature?
The tract that is severed in order to suffer a loss of pain and temperature would be the spinothalamic or lateral spinal tract. The spinothalamic tract is an ascending tract that carries information upwards. -This loss would be contralateral since it is on the opposite side of the damage

Tracts are composed of
White matter

Afferent axons have their cell bodies in the …
dorsal root ganglion

efferent axons leave the spinal cord via the …
Ventral route

Sensory Unit
an afferent neuron and all of the receptors that send information along it. Terminates in the dorsal horn of the spinal cord or medulla.

is the area of skin supplied by a single spinal nerve transmitting to a dorsal root ganglion and spinal cord segment

Explain how sensory information is converted into electrical information for the nervous system.
Sensory information is picked up by sensory receptors
Sensory receptor translates nonelectrical forms of environmental energy into electrical events (nerve action potential) that can be transmitted and processed by the nervous system
Stimulus deforms cell membrane of the receptor, making it more permeable to Na ion influx and raising the threshold
If threshold is reached, localized depolarization occurs
Results in current through axon membrane that eventually creates action potential.
Specific ascending pathways carry action potential of a single type of sensory information to the CNS
Perception of sensory information first is crudely perceived in the thalamus of brain. Then, full interpretation takes place in the somatosensory cortex.

Define Brown-Sequard syndrome
a form of spinal cord injury involving a partial (hemi) transection of the anterior and posterior spinal cord that can result in compromise to PNS function and responses. Characterized by:
– Loss of voluntary motor function (due to corticospinal tract damage)
– Ipsilateral loss of proprioception below lesion (due to damage to dorsal column)
– Contralateral pain and temperature loss below lesion (due to spinothalamic tract damage)
– Ipsilateral loss of all sensation at level of lesion
– Ipsilateral lower motor neuron signs (e.g. flaccid, paralysis) at level of lesion

Is there evidence for Brown-Sequard syndrome in this patient?
Yes, there is evidence for Brown-Sequard syndrome in this patient.
For sensory information, certain information (like proprioception) ascends the dorsal columns and are ipsilateral. Other information (like slow pain or temperature) ascend the anteriolateral system and are contralateral. Ipsilateral means “same side” and this information travels up on the same side as the sensation all the way to the brain then crosses. Contralateral means “opposite side” and this information crosses as it enters the spinal cord, then travels up the opposite side.

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