05-05b: Deep Tendon Reflexes (DTR), UMN/LMN Lesions

Question 1

Reflex

Answer 1

Involuntary, predictable, specific response to stimulus

Question 2

Deep Tendon Reflex

Answer 2

• Motor response in response to sensory stimulation (When tendon is stretched, elicits muscle contraction)
• Stretch-sensitive IA afferent fibers of the muscle spindle produce a muscle contraction in response to a quick stretch stimulus

Question 3

Intact Reflex Arc

Answer 3

Sensory receptor –> afferent neuron (sensory to CNS) –> efferent neuron (away from CNS) –> responding muscle
- Monosynaptic pathway

Question 4

DTR Testing

Answer 4

• Tested with a reflex hammer

- Hammer taps the tendon –> immediate and observable response

Question 5

Grading reflexes

Answer 5

0 = No response
1+ = Diminished/depressed response
2+ = Active normal response
3+ = Brisk/exaggerated response
4+ = Very brisk/hyperactive; abnormal response

Question 6

Hyporeflexia

Answer 6

Difficulty eliciting a reflex

Question 7

Hyperreflexia

Answer 7

Exaggerated reflex

Question 8

Reinforcing techniques to decrease reflex inhibition

Answer 8

• Enhance LE reflex (Jendrassik maneuver): pt hooks fingers together and pull as if pulling apart
• Enhance UE reflex: Squeeze knees together, clench teeth, make a fist on contralateral extremity
• Document use of reinforcement technique

Question 9

DTRs and Lesions

Answer 9

• Increased DTRs with UMN lesions: Ex - Stroke, BI

- Decreased DTRs with LMN lesions: Ex - Cerebellar syndrome, muscle disease, peripheral neuropathy

Question 10

DTR Innervations

Answer 10

Jaw = CN V
Biceps Tendon = C5-C6
Brachioradialis Tendon = C5-C6
Triceps Tendon = C7-C8
Patellar Tendon = L3-L4
Achilles Tedson = S1-S2

Question 11

Superficial Cutaneous Reflex

Answer 11

• Not DTR
• Light stroke applied to skin
• Brief contraction innervated by same spinal segment

Question 12

Babinski Reflex

Answer 12

• Present in infants until 2 years, (adults = BI)
• Stroke lateral foot across metatarsal heads –> toe extension
• Abnormal response: Dorsiflexion of great toe with fanning of the other toes
• Possible upper motor neuron injury

Question 13

UMN Lesions locations

Answer 13

• Occurs in descending motor tract within the CNS (Corticospinal tract)
• Cerebral motor cortex
• Internal capsule
• Brainstem
• Spinal cord

Question 14

Examples of UMN lesions

Answer 14

• Cerebral palsy
• Hydrocephalus (Fluid in the brain)
• CVA (TIA, hemorrhagic stroke, embolism)
• MS (Plaques in the brain)
• Brain tumors

Question 15

Signs of UMN Lesion

Answer 15

• Weakness or paralysis,
• Hypertonicity
• Hyperreflexia
• Mild disuse atrophy (no control of movement)
• Abnormal reflexes (reimergence of already integrated reflexes)

Question 16

LMN Lesion locations

Answer 16

Affects nerve or axons below the level of the brainstem or at the ventral gray column of the SC (after the synapse)

Question 17

Examples of LMN lesions

Answer 17

• Poliomyelitis
• Spinal cord tumors
• Trauma (SCI, Peripheral nerve)
• Infection
• Muscular Dystrophy
• Peripheral nerve lesions

Question 18

Signs of LMN Lesion

Answer 18

• Flaccidity or weakness of involved muscles
• Decreased tone
• Fasciculations (coarse muscle twitching)
• Muscle atrophy (message does not get the muscle to contract)
• Decreased or absent reflexes

Question 19

Fasciculations

Answer 19

Coarse muscle twitching (multiple muscle fibers) seen with peripheral motor nerve injury

Question 20

Fibrillations

Answer 20

Fine, rarely visible, twitching of single muscle fibers, seen with peripheral motor nerve injury