Thirteen

Question 1

What are 6 spinal cord syndromes? When will paralysis result? What kind of paralysis do they result in? What would result in acute spinal cord injuries such as Hemiplegia, Quadriplegia, Monoplegia, and Paraplegia?

Answer 1

Complete Transection—>Quadriplegia if above cervical enlargement, paraplegia if below.
Dorsal Column Syndrome
Central Cord Syndrome
Posterolateral Syndrome
Brown-Sequard Syndrome (half)—>hemiplegia if above cervical enlargement, monoplegia if below.
Anterior Cord Syndrome

They result in a spastic, complete paralysis if and only if the lateral corticospinal tract is damaged.

Question 2

What is spinal shock? What causes it? What are 5 acute symptoms? What are 3 enduring clinical signs and one possible?

Answer 2

Acute and Severe Trauma to Spinal Cord (T6)

• Flaccid paralysis below lesion (transient)
• Areflexia (transient)
• Hypotonicity (transient)
• Moderately decreased blood pressure
• Decreased sphincter tone

Enduring Clinical Signs

• Spastic paralysis, exaggerated deep tendon reflexes, Babinski sign
• Possible partial recovery of ANS function

Question 3

What happens in a contusion injury to the spinal cord? What causes it? What is a common name for it? What is the result?

Answer 3

It is caused usually by trauma. Basically, there is bruising in the spinal cord resulting in ischemia. The gray matter is more susceptible so an astrocytic scar is formed in the center of the cord (cavitations) with possible function on the periphery.

Question 4

How does spinal cord damage affect bladder, bowel, and sexual dysfunction?

Answer 4

Bladder, Bowel and Sexual Dysfunction – Micturition, defecation and sexual function are under both autonomic regulation and lower motor neuron control of sphincters and the pelvic floor musculature. Autonomic sympathetic and parasympathetic fibers control smooth muscle and visceral activities whereas skeletal muscles forming the external urethral and anal sphincters and the pelvic floor are innervated by lower motor neurons. An automatic reflex bladder (incontinence and incomplete emptying) occurs as the result of loss of supraspinal projections. Fecal incontinence is common due to the loss of voluntary control of the anal sphincter. Ejaculation in males is impaired by the loss of contraction of the pelvic floor musculature.

Question 5

What are 2 types of chronic spinal cord injury? What are 3 possible causes? What is sacral sparing?

Answer 5

Central Cord Syndrome and Central Cord Caviation
• Syringomyelia
• Infection
• Inflammation

In central cord syndromes, sometimes the damage will be localized to the center of the cord then start progressing outward. Since the dorsal sensory tract, the pain tract, and the lateral corticospinal tract are arranged with the cervical levels in the center and the sacral levels in the periphery, they sacral levels are often spared, or at least are the last affected.

Question 6

What are 3 possible causes of spasticity due to increased firing of LMNs? What are 2 treatments?

Answer 6

Spasticity is due to increased firing of LMNs

• Increased synaptic efficacy (plasticity) of
primary afferents and monosynaptic reflexes (they replace UMN axons)
• Increased gamma motor neuron activity
• Loss of descending activation of inhibitory
interneurons leading to disinhibition of LMNs

Treatment
• Dorsal Rhizotomy
• Chronic Baclofen

Question 7

What are 3 cortical areas surrounding the primary motor cortex? What is their general function? What specifically does damage to each result in? What is apraxia?

Answer 7

Cortical areas surrounding the primary motor cortex defined as the supplementary motor cortex (medial
surface of area 6), the premotor cortex (lateral surface of area 6) and the posterior parietal cortex (areas 5 and 7) affect voluntary movements directly and indirectly. A relatively few corticospinal axons originate from premotor and posterior parietal areas of cortex. The more numerous and functionally more important projections from areas 6, 5 and 7 are to the primary motor cortex. Since increased neural activity occurs in the supplementary and premotor earlier than in the primary motor cortex these areas are thought to be instructional to the primary motor cortex for initiating complex, multi-joint movements. This conclusion is consistent with clinical observations that localized damage to area 6 results in abnormal movements without paresis . Damage to the supplementary motor area results in disjointed use of homologous muscle groups on both
sides of the body. Damage to the premotor cortex indicates this area is important for visually guided movements. Finally damage to the posterior parietal cortex results in the inability, without paresis, of performing goal-directed tasks.

Apraxia-Damage to premotor cortex results in the inability to initiate complex, multi-joint movements despite a lack of paresis.

Question 8

Where is the damage that causes capsular stroke? What is the result? How can some function be recovered?

Answer 8

Damage to the posterior limb of the internal capsule on one side involving descending corticospinal and corticobulbar axons will result in deficits in voluntary movements, but not necessarily complete paralysis on the contralateral side. Descending motor pathways originating in the brainstem and terminating indirectly on lower motor neurons via propriospinal neurons can mediate recovery of some volitional movements. Highly skilled movements, including speech and fractionated or independent movements of the fingers, toes and facial musculature will not recover.

Question 9

What happens with bilateral damage to the brainstem? Why? What is decorticate posturing? What causes it? What is decerebate posturing? what causes it? Bilateral damage in which areas will result in death?

Answer 9

Brainstem Impairment

Bilateral damage to the brainstem results in level specific clinical signs which, because the patient is probably comatose (cut off connection between brainstem and cortex. The reticular activating system can’t wake the brain), will be manifested in abnormal postures. These abnormal postures can be helpful in localizing the level of the brainstem impairment.

Decorticate Posturing – When the brainstem is impaired at the level of the rostral midbrain-caudal diencephalon the comatose patient will display a posture characterized
by extension of the lower limbs and flexion of the upper limbs. This posture is due to facilitation of upper limb flexor motor neurons by intact rubrospinal projections and
extension of the lower limbs results from the unopposed actions of descending pontine and medullary projections that predominately facilitate lower limb extensor motor
neurons.

Decerebrate Posturing - Brainstem impairment between the levels of the red nucleus and the vestibular nuclei (midpons) results in abnormal posturing characterized by
extension of both the upper and lower limbs. This extensor posture is due to descending reticulo- and vestibulospinal projections.

Bilateral impairment of the lower brainstem (medulla) and rostral spinal cord (down to the level of C3) results in death due to damage to vital cardiovascular and respiratory centers in the medulla or descending projections to the phrenic nucleus in the spinal gray at C4-6.