Lec 3: UMN and LMN Pathology

Question 1

UMN Syndrome may involve what?

Answer 1

-Motor cortex and pathways
-Brainstem
-Cerebellum
-SC reflexes and coordination

Question 1

What corresponds with an UMN lesion?

Answer 1

-collection of neurologic signs and symptoms (postures, postural responses, passive mvmts, active mvmts, and involuntary responses)

Question 2

UMN syndrome injuries reside where?

Answer 2

-several areas of brain and SC
-major areas: motor cortex or brainstem
-motor pathways from major brain areas
-SC involving motor output

Question 3

LMN syndrome injuries reside where?

Answer 3

-AHC or peripheral nerve
-cranial nerve (PN)

Question 4

UMN Syndrome is the result of….

Answer 4

-a disruption of central motor pathways (arise from cerebral cortex and pathways in SC)

Question 5

Define central motor pathways?

Answer 5

connections to the motor systems from cerebral cortex and in spinal cord

Question 6

What are the six central motor pathways?

Answer 6

-Corticospinal Tracts (voluntary motor control)
-Corticobulbar Tracts (cranial nerves)
-Lateral and Medial Reticulospinal Tracts (muscle tone/cerebellum)
-Lateral and Medial Vestibulospinal Tracts (AMN/reflexes)
-Rubrospinal Tracts (cerebellum and BG)
-Tectospinal Tracts (vision and auditory stimulation to turn head)

Question 7

Classic UMN Syndrome

Answer 7

Weakness, Spasticity, Decreased Muscle Control, Hyperreflexia (exaggerated DTR), Clonus

Question 8

Define weakness and decreased muscle control?

Answer 8

Weakness: loss of CNS drive (groups of muscles vs PN innervated muscles)

Decreased muscle control: changes in selective function

Question 9

Define hyperreflexia, and clonus in UMN syndrome

Answer 9

Hyperreflexia: Increase muscle response to tendon tap

Clonus: repeated rhythmic contractions of individual muscle groups

Question 10

Tone definition and what tone reflects

Answer 10

Tone is resistance to passive stretch as a patient is attempting to maintain a relaxed state of muscle activity (excludes joint, skeletal, ligamentous abnormalities). Tone is a normal balance between excitatory and inhibitory control.

Tone reflects the muscle’s state of relaxation (must test at every joint in flexion, ext, ABD, & ADD). It is independent of strength, coordination or involuntary movement.

Question 11

What is the range of muscle tone and where is UMN and LMN in the range?

Answer 11

Range= flaccidity–hypotonia–normal–hypertonia–rigidity

LMN characterized by flaccidity, while UMN is characterized by flaccidity only initially. UMN is later classified by hypertonia.

Question 12

Define hypertonia and it’s 3 classifications

Answer 12

Increase in passive muscle tightness (abnormally increased resistance to an external force about a joint)

1. Spasticity
2. Rigidity
3. Dystonia

Question 13

Definition of Spasticity

Answer 13

A motor disorder characterized by velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyper-excitability of the stretch reflex, as one component of the UMN syndrome.

Question 14

Definition of rigidity and dystonia

Answer 14

Rigidity: significant increase in resistance to multidirectional external forces about a joint

Dystonia: a state of abnormal muscle tone resulting in muscular spasm and abnormal posture, typically d/t neurological disease or side effect of drug therapy

Question 15

Movement based sign of UMN lesion

Answer 15

Synergistic movements or abnormal movements
e.g. flexor synergy/extensor synergy

Question 16

Common upper limb postures or joint positions in UMN syndrome

Answer 16

Flexed elbow, Bent wrist, Pronated forearm, Clenched fist, Thumb in palm

Question 17

Movement based problems associated with additional brain structures

Answer 17

Ataxia (loss of coordination, tremors, overshooting mvmt, loss of velocity) associated with cerebellum

Bradykinesia (slow mvmt) associated with BG (common in PD)

Dystonia (state of abnormal muscle tone resulting in muscular spasm and abnormal posture) associated with BG (esp in Huntington’s chorea)

Question 18

Loss of ROM over time in UMN lesions leads to…

Answer 18

contracture development

Question 19

Neuromuscular changes and associated sensory loss with UMN lesions

Answer 19

-loss of selective mvmt, muscle hyperreflexia, muscle hypertonia
-loss of proprioception, light touch, pin prick

Question 20

Range of hyperactive reflexes

Answer 20

Absent -4
Just Elicitable -3
Low Response -2
Mod Low -1
Normal 0
Brisk +1
V Brisk +2
Exhaustible Clonus +3
Continuous Clonus +4

Question 21

What are “associated movements” in hyperractive reflexes

Answer 21

Moving one body part causes involuntary movement of another body part

Question 22

Advanced brain lesions are involved with what structure and cause what?

Answer 22

-involved with the brainstem
-cause severe motor and sensory disruption “posturing”

Question 23

What is “posturing” in advanced brain lesions

Answer 23

All limbs are “fixed” in a posture with limited limb movements, associated with rigidity.
-extension posturing, elbows extended (decerebrate rigidity)
-abnormal flexion, bent elbows (decorticate rigidity).

Question 24

UMN Signs

Answer 24

-initially flaccid, later develops spasticity -reflexes hyperactive -synergistic movement -clonus variable -sensory loss variable (loss of joint position sense) -CN changes or loss (vision/facial weakness) -bladder changes

Question 25

CVA or stroke signs

Answer 25

-hemiparesis or hemiplegia -visual changes (Horner's syndrome, Homonymous, Hemianopsia) -headache, mental changes, aphasia -hyperthermia, vomitting -apraxia

Question 26

SCI Vertebral Body Fracture Types

Answer 26

Compression injury, flexion or extension injury

Question 27

Clinical Syndromes of incomplete SCI

Answer 27

-Central cord (large lesion, cervical, hyper extension) -Brown Sequard (hemisection of spinal cord) -Anterior Cord

Question 28

Brown Sequard SCI presentation

Answer 28

Ipsilateral vibration and position sense loss and motor loss Contralateral pain and temperature sense loss

Question 29

Central Cord SCI

Answer 29

bilateral pain and temperature loss spinothalamic crossing over at specific level of injury

Question 30

LMN Lesion Signs

Answer 30

1. Loss of muscle function (weakness or flaccid) -peripheral nerve injury/spinal nerve root injury -range is from weakness to paralysis 2. Loss of sensory function from n. damage -proprioception, touch, and pain (peripheral) n. 3. Tone: Hyporeflexia -no response to weak tendon tap

Question 31

Additional LMN Lesion Signs

Answer 31

-Fibrillations= muscular twitching involving indv muscle fibers acting w/o coordination -Fasciculations= caused by increased receptor concentration on muscles to compensate for lack of innervation -Hypotonia or atonia -Hyporeflexia= along with DTR and cutaneous reflexes also decreased/absent -Strength= weakness limited to segmental or PNerve pattern (myotome nerve roots OR PNerve presentation) -Sensation= loss of discriminative touch, light touch, pain, temperature, vibration, pressure, and joint position

Question 32

Peripheral Nerve Injury Types

Answer 32

1. Neuropraxia: loss of myelin = weakness 2. Axonotmesis: loss of axon and myelin= weakness, atrophy, sensory loss. Wallerian Degeneration (anything distal to injury degenerates) 3. Neurotmesis: complete transection of nerve, recovery more difficult due to neuroma formation. Wallerian Degeneration.

Question 33

Peripheral Nerve Injuries of Nerve Root

Answer 33

1. Herniated disc compressing spinal nerve 2. Foraminal Stenosis

Question 34

Injury to PNerve in Carpal Tunnel Syndrome: Clinical Presentation and Muscles Involved

Answer 34

Median Nerve Injury -Atrophy muscle, Weakness/Paralysis, Pain along nerve distribution, numbness along nerve, sensory loss (light touch and position sense) over nerve, ROM loss over time -Flexor pollicis brevis, opponens pollicis, abductor pollicis, distal to injury site

Question 35

Examination of Peripheral Nerve Injury

Answer 35

1. Muscle Testing -test muscles in uninvolved side first, test muscles in involved side, test muscles of adjacent peripheral nerves (ulnar and radial) 2. Sensory Testing -ask about pain (type, location, aggravation, reduction) -test sensation (light touch, pin prick to uninvolved side first) -be sure to test sensation of adjacent peripheral n.

Question 36

Injury to Deep Peroneal Nerve: Clinical Presentation, Signs & Symptoms, and Muscles Involved

Answer 36

-Hyporeflexia, muscular weakness along PN distribution, sensory loss in common fibular distribution -Numbness and tingling, shooting pain along nerve, pain w/ nerve tapping, pain at rest -Peroneus longus and brevis, TA, EHL, EDL

Question 37

Injury to Cervical 5-6 Nerve Root: Signs & Symptoms and Muscles Involved

Answer 37

Radiculopathy -follows C6 dermatomal pattern, hyporeflexia, decreased DTR, weakness, sensory loss, pain, numbness, and tingling following nervous system distribution -Biceps, brachioradialis, wrist extensors (ECR)

Question 38

Other neuropathy: LMN

Answer 38

1. Diabetic Neuropathy -diseased blood vessels —> nerves shrivel when BV disappear -length dependent -first symptoms in feet -glove and stocking presentation 2. Polyneuropathy -distal symmetric

Question 39

Testing for LMN Injury: Peripheral vs Spinal N Root

Answer 39

1. Peripheral nerve: -locate injury at a specific location -Tinel’s sign -nerve injury follows pathway of the peripheral n -muscle and sensory loss below level of injury -weakness and hyporeflexia 2. Spinal Nerve Root: -injury at a spinal nerve -injury follows a myotome and dermatome pattern

Question 40

Upper Motor Neuron and Lower Motor Neuron Chart: Strength, Tone, Reflex Strength, Wasting, Causes

Answer 40

1. LMN Strength: weakness/paralysis Tone: decreased or absent tone Reflex: decreased or absent reflex strength Wasting: rapid muscle wasting Causes: poliomyelitis, motor neuron disease, SCI at segmental level, PN dysfunction, muscle myotonias, myasthenia gravis, muscular dystrophies 2. UMN Strength: weakness/paralysis Tone: increased tone Reflex: increased reflex strength + Babinski sign Wasting: muscle mass maintained Causes: Stroke (contralateral symptoms), cord section