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Pod Med III > 1) Introduction to Lower Neurology > Flashcards

1) Introduction to Lower Neurology Flashcards

1
Q

Each axon is surrounded by

A
  • Endoneurium
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2
Q

Axons bundled into

A
  • Fascicles
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3
Q

Fascicles are held together by

A
  • Perineurium
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4
Q

Bundles of perineurium encased nerved form

A
  • Nerve proper

- Held together by the epineurium on the outside

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5
Q

Each nerve fascicle/fasciculus is a bundle of

A
  • Funiculi
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6
Q

Prolongation of nerve cytoplasm

A
  • Axonlemma
  • Axoplasm
  • Axoplasmic flow
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7
Q

Axonlemma

A
  • Very thin outer layer
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8
Q

Axoplasm

A
  • Viscous material contained within axonlemma
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9
Q

Axoplasmic flow

A
  • Transmit substances ante- and retrograde direction
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10
Q

Cellular process responsible for movement of mitochondria, lipids, synaptic vesicles, proteins, and other organelles toand from a neuron’s cell body

A
  • Axonal transport

- Axoplasmic transport/flow

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11
Q

Myelin is produced by

A
  • Schwann cells

- Interrupted by nodes of ranvier

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12
Q

Axon potential carried via

A
  • Saltatory conduction

- Rate of conduction is proportionate to nerve diameter

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13
Q

Dorsal nerve roots carry

A
  • Sensory neural signals to the central nervous system (CNS) from the peripheral nervous system (PNS)
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14
Q

Dorsal root ganglion (DRG)

A
  • Association with neuropathic pain
  • Emerge from the dorsal root of the spinal nerves, carrying sensory messages from various receptors
  • Pain and temperature towards the central nervous system for a response
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15
Q

Afferent neurons

A
  • Sensory nerves
  • Carry signals to the brain and spinal cord assensory data
  • Neuron’s response: send an impulse through the central nervous system
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16
Q

Efferent neurons

A
  • Motor nerves

- Carry neural impulses away from CNS toward muscles to cause movement

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17
Q

A fibers (2-22 microns)

A
  • Myelinated afferent and efferents
  • Alpha
  • Beta
  • Gamma
  • Delta
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18
Q

A alpha fibers

A
  • Largest

- Motor, proprioception, and reflexes

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19
Q

A beta fibers

A
  • Muscles
  • Touch
  • Proprioception
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20
Q

A gamma fibers

A
  • Muscle tone
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21
Q

A delta fibers

A
  • Pain and temperature
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22
Q

B fibers

A
  • Preganglionic autonomic nerves
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23
Q

C fibers (0.5-1 micron)

A
  • Poorly or unmyelinated nerves
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24
Q

Nerve fibers are classified according to

A
  • Diameter
  • Degree of myelination
  • Speed of conduction
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25
Group A fibers
- Large diameter - Myelinated - Somatic sensory and motor fibers
26
Group B fibers
- Intermediate diameter | - Lightly myelinated `ANS fibers
27
Group C fibers
- Smallest diameter | - Unmyelinated ANS fibers
28
Loose connective tissue layer about an axon
- Endoneurium
29
Endoneurium inner layer
- Outside and around Schwann cells - Myelinating cell of the PNS - Dips at nodes of Ranvier
30
Endoneurium outer layer
- Does not "dip" | - Blood-nerve barrier
31
Perineurium
- Binds together fascicles of endoneural sheaths - Layers proportionate to number of fascicles within - Contain “tight junctions”
32
Perineurium tight junctions
- Possess unique diffusion properties | - Create barrier against infectious agents
33
Epineurium ancases perineurium covered fascicles and contains
- Collagen and elastin fibers - Mast cells and fibroblasts - Lymph vessels
34
Class I neuropraxia (Seddon's)
- Transient loss of conductivity - Motor fibers very susceptible - Recovery within days to weeks
35
Class II axonotmesis (Seddon's)
- Axons damaged but the neural tube is intact - Wallerian degeneration occurs - Regeneration: 1 – 2 mm/day - Presence of Tinel’s sign
36
Class III neurotmesis (Seddon's)
- Structural framework divided, torn or destroyed - Wallerian degeneration occurs - Regeneration may be impossible - May develop into a bulbous or a stump neuroma
37
Tinel's Sign
- Feet at edge of table - Tap PT nerve - Positive = radiating pain/tingling - Indicates tarsal tunnel syndrome
38
First degree nerve injury (Sunderland's)
- Transient conduction deficit - Perhaps mild demyelination - May have an “irritable” phase
39
First degree nerve injury (Sunderland's) may occur secondary to
- Compression - Tourniquets - Tight shoe gear - Blunt trauma - Nondisplaced fractures
40
Second degree nerve injury (Sunderland's)
- Seddon’s “axonotmesis” - Axon severed within intact endoneurium - Undergoes Wallerian degeneration - Regeneration occurs - Positive Tinel’s sign
41
Third degree nerve injury (Sunderland's)
- Involves axon and fascicles - Some degree of endoneural scarring - May require up to 6 months to determine extent of injury - Regeneration occurs but unpredictable - Residual deficit should be expected in sensation or motor - To prevent fibrosis motor innervation must be restored
42
Fourth degree nerve injury (Sunderland's)
- “Neuroma in Continuity” - Neuroma that results from failure of the regenerating nerve growth cone to reach peripheral targets - Axon, endoneurium and perineurium are disrupted
43
Fourth degree nerve injury (Sunderland's) occurs within an intact nerve in response to
- Internally damaged fascicles, resulting in a distal portion of the nerve that no longer functions properly - No possible regeneration!!!!
44
Fifth degree nerve injury (Sunderland's)
- Complete transection of nerve | - May develop “stump” neuroma
45
Fifth degree nerve injury (Sunderland's) common etiologies
- Laceration | - Rupture from stretch
46
Sixth degree nerve injury
- Introduced by Susan Mackinnon in 1988 | - A combination of nerve injuries within one singular nerve
47
Detection of motor nerve injury
- Flaccid paralysis → atrophy - Acetylcholine receptors begin to regenerate causing fibrillations - Unique to lower motor neuron lesion!! - Detect with EMG
48
Detection of autonomic nerve injury
- Anhidrosis (inability to sweat)
49
Microscopic detection of nerve injury
- Presence of Wallerian degeneration
50
One major characteristic to identify lower motor neuron lesion
- Flaccid paralysis | - Paralysis accompanied by loss of muscle tone
51
Identifying an upper motor neuron lesion
- Spastic paralysis | - Paralysis accompanied by severe hypertonia
52
Recognition of nerve recovery
- Motor function return in most proximal muscle - Sensory function return (deep sensation, proprioception) - Distal progression of Tinel’s sign (lack of progress suggests surgical intervention required)
53
Nerve recovery is better if...
- Injury occurs at younger age - Wound is clean and uncontaminated - No crush or traction element - Primary repair occurs within hours - Delayed repair within 5 to 7 days - The injury is more distal - A predominantly sensory or motor nerve (not mixed)
54
Two types of nerve repair
- Primary | - Delayed
55
Epineurial nerve repair (primary)
- End-to-end - Sutured without tension - Use of “traction” suture - Blood vessels may act as anatomical landmarks - Monofilament nylon (7-0 to 11-0) epifascicular sutures
56
Repair of nerve deficit can use
- Nerve graft - GEM neurotube - Silicone tubing
57
Nerve graft
- Sural nerve donor | - End to end anastomosis
58
GEM neurotube
- Absorbable woven polyglycolic acid mesh
59
Silicone tubing
- Type I collagen - Neurocrescin )increases numbers of fibers) - MDP-77 (aids in terminal and collateral sprouting and nerve maturation)
60
Descending spinal tracts (motor)
- Lateral corticospinal | - Ventral corticospinal
61
Ascending spinal tracts (sensory)
- Dorsal columns - Lateral spinothalamic - Ventral spinothalamic
62
Lateral corticospinal tract
- Main voluntary motor | - Upper extremity motor pathways are more medial (central)
63
Ventral corticospinal tract
- Voluntary motor
64
Dorsal columns
- Deep touch - Lower extremity input in most medial location - Sensory Modalities - Light Touch - Vibratory Sense - Proprioception(Conscious Position Sense)
65
Lateral spinothalamic tract
- Pain | - Temperature
66
Ventral spinthalamic tract
- Light touch
67
Dorsal columns are made up of
- Fasciculus gracilis | - Fasciculus cuneatus
68
Dorsal columns pathway
- Ascend on the same side to brain stem | - Fibers decussate at the brainstem continuing to the thalamus
69
Dorsal column testing
- Vibratory sense w/ tuning fork - Position sense - Conscious proprioception w/ Romberg test
70
Romberg test
- Measures balance
71
Lateral spinothalamic tract pathway
- Enter and ascend one or two vertebral levels - Decussate within the cord - Travel to thalamus and continue to cerebral cortex
72
Lateral spinothalamic tract sensory examination
- Sharp/dull - Pain Perception - Temperature - Most sensitive indicator of small fiber neuropathy - Affects A-delta and autonomic C (unmyelinated) fibers
73
Spinocerebellar tract sensory modalities
- Unconscious proprioception | - Stereognosis
74
Spinocerebellar tract pathway
- Proprioceptive fibers ascend completely ipsilateral | - Enters cerebellum via superior and inferior peduncles
75
Corticospinal tract
- Primary efferent motor pathway - voluntary motor control - UMN lesion - Pyramidal tract disease
76
Corticospinal tract pathway
- Exits the cerebral cortex - Travels through the medullary pyramids and decussate – 80% of fibers – lateral tract - Travel to anterior motor horn cells
77
Pyramidal tract lesions will present very similarly to upper motor lesions with symptoms such as
- Hyperreflexia - Weakness - Spasticity - (+) Babinski sign
78
The corticospinal tract, AKA, the pyramidal tract
- Major neuronal pathway providing voluntary motor function | - Connects the cortex to the spinal cord (enable movement of the distal extremities)
79
Systemic illnesses affecting neurological function
- Hypothyroidism - Diabetes - Hereditary disorders
80
Skin associations with neuro dysfunction
- Trophic changes - Nails - Birthmarks - Hypopigmentation
81
Facial features of neuro dysfunction
- Head size - Genetic abnormalities - “Myopathic” face (facial appearance characteristic of myopathic conditions) - Ptosis
82
Myopathic face
- Face appears expressionless with sunken cheeks, bilateral ptosis, and inability to elevate the corners of the mouth, due to muscle weakness
83
Extremity findings with neuro dysfunction
- Muscle wasting - Spastic paralysis - Flaccid paralysis - Pseudohypertrophy - Cavus foot - Intrinsic minus foot - Gait abnormalities (steppage, scissor, Neri's sign)
84
Anesthesia
- Complete loss of sensation
85
Analgesia
- Loss of pain sensation
86
Heightened perception
- Hyperesthesia - Hyperalgesia - Hyperpathia
87
Decreased perception
- Hypesthesia | - Hypoalgesia
88
Hyperpathia
- Painful syndrome characterized by an abnormally painful reaction to a stimulus, as well as an increased threshold
89
Hyperalgesia
- Augmented pain response - Increased pain response to a painful stimulus - Pain threshold may be lowered
90
Distal polyneuropathy
- Stocking glove distribution - Compare distal to proximal sensation - Loss is more profound distally
91
Examples where you may see distal polyneuropathy
- Diabetes - Metabolic Neuropathies - Infectious Neuropathies
92
Dermatomal loss may benefit in identifying
- Radicular injury - Spinal stenosis - Disc herniation - Tissue mass
93
Peripheral nerve course
- Testing along a specific nerve | - Deficits are common with compression neuropathies and trauma
94
Dorsal column nerve testing
- Light touch (cotton wisp) - Vibratory (most sensitive, C-128 tuning fork, biothesiometer) - Biothesiometer < 25 suggests infection risk
95
Lateral spinothalamic tract pain sensory testing
- Done over dermatomal distribution | - Quantitate “sharp” versus “dull” – not pressure
96
Lateral spinothalamic tract temperature sensory testing
- Ability to sense cold | - Be aware of presence of any vasospastic disorder
97
Protective threshold used to determine
- Foot's ability to protect itself | - Semmes-Weinstein monofilament (5.07 10 gram)
98
Diabetic sensory neuropathy testing
- Pressure specified sensory device – PSSD | - Most accurate way of testing the lower extremity for sensory deficits
99
Positive Babinski (corticospinal lesion) associated with
- UMN lesion - Paraventricular leukomalacia from brain injury - Muscle spasticity and increased stretch reflex
100
Babinski sign
- Present until 6 months to two years - Evaluates pyramidal tract disease (aka corticospinal tract dx) - Dorsiflexion of the hallux with plantarflexion and fanning of the lesser digits - Distinguish from plantar withdrawal response
101
"Babinski-like" reflexes
- Chaddock's sign - Oppenheim's test - Gordon's sign - Rosolimo's sign
102
Chaddock's sign
- Stroke the lateral aspect of the foot | - Proximal to distal behind the lateral malleolus
103
Oppenheim's test
- Using the thumb and finger as a caliper squeeze the tibial crest
104
Gordon's sign
- Squeeze the posterior calf | - Positive with dorsiflexion of hallux
105
Rosolimo's sign
- Percuss the distal digital pulps | - Positive with plantarflexion of the lesser digits
106
5 components of the nervous system evaluated with deep tendon reflex
- Intact sensory afferent - Functional synapse at the spinal cord level - Intact motor nerve - Functional neuromuscular junction - Competent muscle
107
Deep tendon reflex grading
- 4+ = Brisk – associated with clonus - 3+ = Brisker than normal – hyperreflexic - 2+ = Average - 1+ = Low normal – hypo-reflexic - 0 = Absent
108
Jendrassik maneuver
- "Recruitment” - Patient pulls hands prior to you doing reflex - Eliminates their conscious resistance
109
Deep tendon reflexes and their root levels
- Patellar – L2-L4 - Achilles (ankle) – S1-S2 - Biceps – C5-C6 - Triceps – C7-C8 - Clonus
110
Cerebellar examination
- Dictates smooth coordination of voluntary movements - Helps maintain posture, balance and unconscious proprioception - Contributes to vestibular function - Heel-Knee test
111
Stork leg deformity
- In patients with Charcot-Marie-Tooth disease (CMT), distal muscle wasting may be noted in the legs - Resulting in the characteristic stork leg or inverted champagne bottle appearance

Pod Med III (8 decks)

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