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

05 - Tests and Measurements > 05-05b: Deep Tendon Reflexes (DTR), UMN/LMN Lesions > Flashcards

Flashcards in 05-05b: Deep Tendon Reflexes (DTR), UMN/LMN Lesions Deck (20):
1

Reflex

Involuntary, predictable, specific response to stimulus

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Deep Tendon Reflex

- 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

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Intact Reflex Arc

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

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DTR Testing

- Tested with a reflex hammer
- Hammer taps the tendon --> immediate and observable response

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Grading reflexes

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

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Hyporeflexia

Difficulty eliciting a reflex

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Hyperreflexia

Exaggerated reflex

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Reinforcing techniques to decrease reflex inhibition

- 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

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DTRs and Lesions

- Increased DTRs with UMN lesions: Ex - Stroke, BI
- Decreased DTRs with LMN lesions: Ex - Cerebellar syndrome, muscle disease, peripheral neuropathy

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DTR Innervations

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

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Superficial Cutaneous Reflex

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

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Babinski Reflex

- 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

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UMN Lesions locations

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

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Examples of UMN lesions

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

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Signs of UMN Lesion

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

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LMN Lesion locations

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

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Examples of LMN lesions

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

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Signs of LMN Lesion

- 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

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Fasciculations

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

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Fibrillations

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