Upper and lower motor neuron syndromes

___ to ___ hours after the primary spinal cord injury there is breakdown of the ______ with resultant ____ - this can lead to _____ ___ and ____ of ____ ___ in the spinal cord. Distal to the lesion ____ _____ occurs.

24 to 36 hours after the primary spinal cord injury there is breakdown of the BBB with resultant edema - this can lead to neuronal death and loss of fiber tracts in the spinal cord Distal to the lesion wallerian degradation occurs

A motor unit comprises one ____ ____ ____ and all of the _____ ____ it innervates via _____ ____

A motor unit comprises one lower motor neuron and all of the muscle fibers it innervates via neuromuscular junctions

Characteristics of lower motor neuron syndrome include _____ ____ or ____ - due to destruction of the ____ ___ ___ the ___ do not respond to ___ or ____ activation. There is decreased ____ ___ ______ ____ - the bulk of the muscle may become reduced. This is due to the loss of ____ ____ that _____ normally provide. The ____ is much more pronounced than that caused by _____

Characteristics of lower motor neuron syndrome include flaccid paralysis or paresis - due to destruction of the lower motor neuron the muscles do not respond to voluntary or reflex activation. There is decreased muscle tone Muscle atrophy - the bulk of the muscle may become reduced. This is due to loss of the trophic influence that neurons normally provide. The atrophy is much more pronounced than that caused by inactivity

Corticospinal tract mainly concerned with _____ influence while reticulospinal tract mainly concerned with _____ influence

Corticospinal tract mainly concerned with flexor influence while reticulospinal tract mainly concerned with extensor influence

Lower motor syndrome may cause _____ or ______ of the ____ ___ reflexes. There is damage to the _____ _____ of the ____ ___

LMN syndrome may cause areflexia or hyporeflexia of the deep tendon reflexes - there is damage to the efferent limb of the reflex arc

Spinal cord ____ or _____ ____ produces both the _____ and _____ syndromes. The _____ syndrome manifests substantially ____ than the injury

Spinal cord transection or spinal shock produces both the LMN and UMN syndromes. The UMN syndrome manifests substantially later than the injury

The lower motor neuron is the ____ neuron in the chain of command to a _____ and directly ____ ______ _____. These are also known as _____ _____ neurons. They reside in the _____ _____. Also found in the ____ in a series of ___ ____ of the ____ ____.

The lower motor neuron is the last neuron in the chain of command to a muscle and directly innervates skeletal muscle. These are also known as alpha motor neurons. They reside in the anterior horn. Also found in the brainstem in a series of motor nuclei of the cranial nerves

The most important brainstem ____ are the cells of origin of the descending _____ tracts. Most symptoms of _____ _____ ____ damage are due to the disruption of the _____ _____ _____. This tract normally provides tonic ______ to _____ ____ tone and ____ ____ reflexes. The ____ cortex provides strong _____ to the neurons comprising the _____ ____ ____. Damage either to the ____ ____ or the ____ ____ ____ results in a _______ of the _____ ____ ___ and ____ ___ _____.

The most important brainstem UMNs are the cells of origin of the descending reticulospinal tracts. Most symptoms of upper motor neuron damage are due to the disruption of the lateral reticulospinal tract This tract normally provides tonic inhibition to extensor muscle tone and deep tendon reflexes. The motor cortex provides strong excitation to the neurons comprising the lateral reticulospinal tract. Damage either to the motor cortex or the lateral reticulospinal tract results in a *disinhibition* of extensor muscle tone and deep tendon reflexes.

UMN syndrome presents with the _____ sign which is present due to loss of _____ _____ biased pathways - this results specifically from interruption of the _____ ____

UMN syndrome presents with the babinski sign which is present due to loss of descending flexor biased pathways - this results specifically from interruption of the corticospinal tract

Cells of origin of the ______ are considered _____. There are also ____ ___ that project to ____ ____ ___ that are considered ______

Cells of origin of the corticospinal tract are considered UMNs. There are also brainstem neurons that project to lower motor neurons that are considered UMNs

Loss of corticospinal tract only? Loss of reticulospinal tract only? These will cause _____ ____ - ____ if only one, ____ if both

Corticospinal tract only - Loss of RIFMs, and Babinski sign Reticulospinal tract only - Hyperreflexia, spasticity, clonus (mainly an inhibitory tract) these will cause UMN syndrome - partial if only one, complete if both

Damage to the motor cortex also results in a loss of _____ _____ _____ due to a disruption of the ____ _____ connection with the _____

Damage to the motor cortex also results in a loss of voluntary motor control due to a disruption of the corticospinal tract connection with the LMNs

LMN syndrome may cause _____ which are due to the agonal discharges of ___ as they are _____ - they ____ in a random, uncoordinated fashion

LMN may cause fasciulations (muscle twitches grossly visible) which are due to the agonal discharges of LMN as they are dying - they fire in a random, uncoordinated fashion

LMN syndrome may cause _____ which are _____ _____ of individual muscle fibers due to ______ ______ - the _____ region of the ____ expands beyond its ____ ____ ___. Cannot be seen grossly but easily demonstrable by _____

LMN syndrome can cause fibrillations which are spontaneous contractions of individual muscle fibers due to denervation hypersensitivity - the endplate region of the sarcolemma expands beyond its normal compact distribution Cannot be seen grossly but easily demonstrable by EMG

Lower motor neurons provide the ____ outflow for several _____ ____ The functional status of the ____ _____ is especially useful in the differential diagnosis of ____ and ___syndromes

Lower motor neurons provide the motor outflow for several reflex arcs The functional status of the stretch reflex is especially useful in the differential diagnosis of LMN and UMN syndromes

Paralysis is ____ ____ of ___ or ______ ____ in the _____ region - this is in contrast to _____ which is when the loss is ____

Paralysis is complete loss of power or voluntary movement in the affected region - this is in contrast to paresis which is when the loss is incomplete

Primary event in spinal cord injury is the spinal cord is _____ or ____ rather than transected

Primary event in spinal cord injury is the spinal cord is bruised or crushed rather than transected

Secondary events in spinal cord injury involve the first __ to ___ hours and are critical. This includes ____ ____ flow with ____ ____ _____ Cells release _____ _____ factors

Secondary events in spinal cord injury involve the first 3 to 6 hours and are critical This includes altered blood flow with oxygen deprivation Hypotension Cells release endogenous toxic factors

Spinal injuries - at the level of the injury, destruction of the _____ ____ ______ ______ produces the _____ syndrome Below the the level of the spinal cord injury, the ______ syndrome is present due to damage of ______ and ______ axons at the _____ of the inury

Spinal injuries - at the level of the injury, destruction of the ventral horn motor neurons produces the LMN syndrome Below the level of the spinal cord injury, the UMN syndrome is present due to damage of corticospinal and reticulospinal axons at the level of the injury

UMN syndrome causes ____ which is _____ ____ of _____ muscle ____ and ____

UMN syndrome causes clonus which is rhythmic oscillation of reflexive muscle contraction and relaxation

UMN syndrome causes ______ of ____ _____ ___ - this is because of a loss of _____ _____ ______ influences. Degree of _____ is expressed as a scale from ___ to ____ and ____ is > ___

UMN syndrome causes hyperreflexia of deep tendon reflexes - this is because of a loss of tonic descending inhibitory influences Degree of hyperreflexia is expressed as a scale from + to ++++ and hyperreflexia is > ++

UMN syndrome causes ____ which is ____ during _____ _____.

UMN syndrome causes spasticity which is stiffness during passive movement

UMN syndrome does not present with ______ because the ____ ____ ____ innervating the ____ are still intact and there is no loss of _____ _____

UMN syndrome does not present with atrophy because the lower motor neurons innervating the muscles are still intact and there is no loss os trophic support

UMN syndrome leads to ______ _____ which is a ______ "____ ___" that occurs when supraspinal influences that normally inhibit _____ reflex are interrupted. _____ emptying occurs at a lower threshold - the external sphincter also becomes _____ so the ____ cannot ____ completely. Coordination between the ____ ___ and ____ ___ is lost - retained ____ leads to ____ ____

UMN syndrome leads to neurogenic bladder which is a hypersensitive "spastic bladder" that occurs when supraspinal influences that normally inhibit micturition reflex are interrupted. Reflex emptying occurs at a lower threshold - the external sphincter becomes hypersensitive so the bladder cannot empty completely. Coordination between the detrusor muscle and interal sphincter is lost - retained urine leads to urinary infections

UMN syndrome results in _____ _____ with _____ because ____ originating in the ____ ___ cannot be transmitted to the _____ and/or _____ ____ - this results in _____ and increased ___ _____. This is known as _____ ___ since _____ ___ still occurs in _____ ____

UMN syndrome results in voluntary paralysis with spasticity because impulses originating in the motor cortex cannot be transmitted to the brainstem and/or spinal cord - this results in paralysis and increased muscle tone. This is known as voluntary paralysis since motor activity still occurs in reflex responses

Upper motor neuron syndrome results in _____ posture with increased tone in the ______ muscles (_____ of the ____ ____)

Upper motor neuron syndrome results in decorticate posture with increased tone in the antigravity muscles (extensors of the lower limb)

Upper motor neurons are _____ neurons that directly innervate ____ ____ ____ and their associated _____ pools.

Upper motor neurons are central neurons that directly innervate lower motor neurons and their associated interneuron pools

With brain damage the symptoms of _____ may be obvious almost immediately.

With brain damage the symptoms of UMN may be obvious almost immediately