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Medicine Year 2 > HNN Topic 14 - Reflex, Spinal Cord Injury > Flashcards

HNN Topic 14 - Reflex, Spinal Cord Injury Flashcards

1
Q

How is sexual function and fertility managed following spinal cord injury?

A
  • Male
    • Viagra
    • Cialis
    • Stimulation
    • Electo-ejaculation
  • Female
    • Assissted conception
    • Pregnancy support
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2
Q

Where are tendon jerk reflexes tested?

A

Tested where there is easy access to tendon e.g. patellar tendon of knees

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3
Q

List the events which occur during the monosynaptic circuit of the knee tendon jerk reflex

A
  1. Stimulus - tendon tap, stretches muscle
  2. Activates mechanoreceptors - muscle spindle receptors
  3. Conduction along afferent (sensory) fibres - 1a fibres, v fast
  4. Transmission at synapses between 1a afferent and motor neuron associated with same muscle - ventral horn of grey matter
  5. Sufficient excitement (above threshold) - conduction along efferent (motor) fibres
  6. Neuromuscular transmission, excitation-contraction coupling
  7. Twitch contraction of skeletal muscle
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4
Q

List the signs/symptoms of spinal shock

A
  • Flaccid paralysis
  • Arreflexia
  • Loss of sensation
  • Loss of bladder/bowel control
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5
Q

How is an acute spinal injury treated?

A

Identify, immobilise, investigate, inform

Initial treatment = stabilisation, decompression

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6
Q

Describe the circuit involved in tendon jerk reflexes

A

Monosynaptic circuit - two neuron reflex are with central synapse (monosynaptic)

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7
Q

How are tendon jerk reflexes used clinically?

A

Gives information about sensory/motor neuropathy and CNS dysfunction

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8
Q

What are the benefits of using a tendon tap to test neurological intactness?

A

Simple, reliable (can’t be faked)

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9
Q

What is a lower motor neuron lesion?

A
  • Affects nerve fibres travelling from the anterior horn of the spinal cord or the cranial motor nuclei to the relevant muscle
  • I.e. peripheral nerve or at nerve root
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10
Q

Define autonomic dysreflexia

A
  • Occurs in injuries occuring T6 or above
  • Experience hypertension in response to noxious stimuli
  • Results in headaches, can be more serious
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11
Q

What typically causes posterior cord syndrome?

A
  • Trauma in neck
  • Occlusion of spinal artery
  • Tumours
  • Disc compression
  • Vitamin B12 deficiency
  • Syphillus
  • Multiple sclerosis
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12
Q

Compare the symptoms/signs of upper and lower motor neuron lesions

A
  • Upper motor neuron lesion
    • Muscle weakness
    • Increased tone
    • Increased reflexes
  • Lower motor neuron lesion
    • Muscle weakness and wasting
    • Reduced tone
    • Reduced reflexes
    • Fasciculations
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13
Q

In spinal cord injuries, at what levels would upper/lower motor neuron lesion signs be present?

A
  • Lesion C1-5 - UMN signs in upper + lower limbs
  • Lesion T3-12 - UMN signs in lower limbs, upper limbs normal
  • Lesion T12-S2 - LMN signs in lower limbs, upper limbs normal
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14
Q

What causes anterior cord syndrome?

A

Ischaemia of anterior spinal artery

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15
Q

Define reflex

A

Involuntary stereotyped response to a stimulus

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16
Q

Define tendon jerk

A

Reflex muscle contraction produced by tendon stretch, useful neurological test

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17
Q

What is the method of action of Jendrassik’s manoeuvre?

A
  • Convert background excitation (not enough to cause firing of action potentials) to firing excitatory signals from brain, overflows to motor neuron pool of lower limb
  • Continuous input from motor neuron pool - raises membrane potential/excitability closer to threshold
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18
Q

List the diseases which distrupt the stretch reflex and describe the impact of this

A

Stroke, spinal cord injury, damage to basal ganglia - change activity in descending pathways, disorders muscle tone e.g. spasticity, accompanied by exaggerated tendon reflexes (hyperreflexia)

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19
Q

Explain the importance of a multidisciplinary team in treating spinal cord injuries

A

Need medical, nursing, physiotherapy, occupational therapy, psychologist, social workers, technologist and support of family/friends

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20
Q

List the types of incomplete spinal cord injuries

A
  1. Central cord syndrome
  2. Anterior cord syndrome
  3. Posterior cord syndrome
  4. Brown-Sequard syndrome
  5. Cauda Equina syndrome
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21
Q

What is the first sign of spinal shock ending?

A

Babinski’s sign is one of the first reflexes to reappear after spinal shock

22
Q

List the tendon reflexes tested clinically and the spinal nerves which innervate them

A
  • Biceps (C5/6)
  • Brachioradialis (C6)
  • Triceps (C7)
  • Patellar (L4)
  • Achilles tendon (S1)
23
Q

Describe the stages of reflexes returning after a spinal cord injury

A
  1. Arreflexia
  2. Initial reflex return
  3. Hyperreflexia - spasticity
24
Q

Define Brown-Sequard Syndrome

A

Hemi-section of the cord, usually due to penetrating injury - stab, gunshot

25
Q

Define neurogenic shock

A
  • Body’s response to sudden loss of sympathetic control in a spinal cord injury above T6 (>50% sympathetic innervation lost)
  • Distribution speed
  • Clinical triad
    • Hypotension
    • Bradycardia
    • Hypothermia
26
Q

What is the normal function of the monosynaptic circuit?

A

The stretch reflex - acts to maintain constant muscle length and tone e.g. for posture

27
Q

How is loss of bladder control due to spinal cord injury managed?

A
  • Catheters - intermittent, indwelling, suprapubic, lofric, silver coated
  • Infection risk - manage with antibiotics
  • Liason staff, urologist
28
Q

How are reflexes tested in clinical practice

A
  • Repeat 4/5x
  • Bilateral comparison
  • Reinforcement
    • Lower limb = Jendrassik’s manoeuvre
    • Upper limb = clench jaw
29
Q

Describe the clinical manifestations of Brown-Sequard Syndrome

A
  • Paralysis of affected side (corticospinal)
  • Loss of proprioception + fine discrimination (dorsal columns)
  • Pain + temperature loss on opposite side below the lesion (spinothalamic)
30
Q

What are the priorities of patients with spinal cord injuries?

A
  • Depends if tetraplegic or paraplegic
    • Paraplegic - walking, bladder/bowel
    • Tetraplegic - arm/hand, walking
  • Older patients - sexual function not top priority
  • Changes over time - long-term bladder/bowel and chronic pain become very important
31
Q

In what situation can tendon jerk reflexes be absent?

A

Holmes-Adie syndrome

32
Q

How is the loss of bowel control managed after spinal cord injury?

A
  • Diet, lactulose, senna
  • Manual evacuation
  • Bowel regime needed
33
Q

Describe how respiration is affected by spinal cord injuries at specific levels

A
  • C3, 4, 5 - diaphragm (phrenic nerve)
    • Injury above this level - no respiratory muscle function
  • Intercostal muscles - C6/7
    • Injury C4-6 - breathing occurs but no accessory muscle function, problems coughing
  • Below C6/7 - breathing not affected
  • Above C6 - may need tracheostomy + artificial ventilation
34
Q

How is bladder control affected by spinal cord injuries?

A
  • Micturition centre = S2-4, most injuries result in degree of loss of bladder control
  • Injury at S4/5 - some control
  • May struggle to empty bladder - loss of sympathetic control in hypogastric nerve (T12-L1)
35
Q

In which situations is Babinski’s sign present and why?

A
  • Babies up to 1 year and spinal cord injuried show Babinski’s sign
  • Two pathways - flexion and extension
  • In neurologically intact adults - extensor pathway suppressed by corticospinal tract
  • In neonates corticospinal tract is not fully mature (unmyelinated)
  • Damage to corticospinal tract e.g. spinal cord injury - re-emergence of Babinski’s sign
36
Q

What causes cauda equina syndrome?

A

Bony compression or disc protrusions in lumbar or sacral regions

37
Q

Describe the ASIA scale ranking of spinal cord injury

A

A = No sensory/motor function below level of injury

B = Sensory (S4/5) but no motor function below level of injury

C = Less than grade 3 motor function below level of injury

D = Grade 3 or above motor function below level of inury

E = Neurologically intact

38
Q

What type of injury typically causes central cord syndrome?

A
  • Typically older patients
  • Hyperextension injury
  • Compression of cord anteriorly by osteophytes, posteriorly by ligamentum flavum
39
Q

What is the outcome of central cord syndrome?

A

Loss of motion and sensation in arms and hands

40
Q

What are the differences between quadreplegia and paraplegia

A
  • Quadraplegia
    • Injury in cervical region
    • All 4 extremities affected
  • Paraplegia
    • Injury in thoracic, lumbar or sacral segments
    • 2 extremities affected
41
Q

How is a spinal cord injury assessed?

A

ASIA Chart

  • Motor = upper limb, lower limb, anal contraction
  • Sensory = pin prick, light touch, sacral sparing
  1. Motor
  2. Sensory
  3. Bladder
  4. Bowel
  5. Sexual
  6. Autonomic
42
Q

How is pain managed following spinal cord injury?

A

Rehabilitation consults, anaesthetic pain service, pain nurse

43
Q

What is the outcome of anterior cord syndrome?

A

Loss of function of anterior 2/3 of spinal cord - loss of voluntary motor function (corticospinal tract) below injury, loss of pain/temperature sensation (spinothalamic tract) but retained proprioception and vibration sensation (DMCL)

44
Q

Describe the clinical manifestations of cauda equina syndrome

A
  • Non-specific symptoms - back pain
  • Bowel + bladder dysfunction
  • Leg numbness and weakness
  • Saddle paraesthesia
45
Q

Describe how limb function is affected by spinal cord injuries at specific levels

A
  • C1-4 - quadreplegia
  • C5 - shoulder, biceps - no wrist/hand control
  • C6 - wrist control, no hand movement
  • C7/T1 - most upper limb control, fine dextrous control of hands/fingers affected
  • T1-8 - paraplegia, poor control of trunk/abdominal muscles
  • Lumbar/sacral - decreased control of hip flexors + legs
46
Q

Define spinal shock

A
  • Temporary suppression of all reflex activity below the level of injury, occurs immediately after injury
  • Can last for 30 minutes - 6 weeks after injury
47
Q

List the common complications of spinal cord injuries

A
  • DVT, pulmonary embolism - high risk due to immobility, prophylaxis
  • Asensate skin - pressure sores, recumbency (lying down), death
  • Pain - acute and chronic
  • Loss of sexual function and fertility
  • Autonomic dysreflexia
48
Q

Describe normal and abnormal plantar reflexes

A
  1. Normal plantar reflex = toe flexion
  2. Babinski’s sign = toe extension
49
Q

What is the stretch reflex

A

Prolonged stretch produces prolonged (tonic) contraction, influenced by descending pathways from brain - can change excitability of motor neuron pool

50
Q

What is an upper motor neuron lesion?

A
  • Lesion of neural pathway above the anterior horn cells of the spinal cord or motor nuclei of the cranial nerves
  • In brain/spinal cord e.g. cerebral infarction or lesion to the corticospinal tract

Medicine Year 2 (41 decks)

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