Peripheral Nerve Pathology Flashcards by Sarah Heath

Where does the PNS start

Intervertebral foramen

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Loss of somatosensation or viscerosensation (numbness)

Anesthesia

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Altered/abnormal somatosenation (tingling)

Pareathesia

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Alternation in the type of sensation experience (painful reaction to normal non-painful stimuli )

Allodynia

Pain sensation that occurs spontaneously without actual pain stimulus present, typically described as ‘burning’, shock-like’ etc

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Affects dorsal (posterior) or ventral (anterior) roots

Radiculopathy

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Etiology of local pathology

Traumatic, compression (by disc herniation or osteophyte, spinal stenosis (narrowing of spinal canal), tumors, access, viruses including varicella-zoster (shingles), cytomegalovirus

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Etiology of systemic pathology

Irritates roots to causes abnormal firing and/or loss of normal firing pattern, including diabetes, infection, inflammation, and auto-immune disease

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Radicular pain

Spontaneous, radiating, shock like, cutaneous and muscle

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Presentation of radiculopathy

radicular pain
anesthesia
paresis
distribution (focal and segmental)
temporal profile (acute, subacute, or insidious)

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Distribution of radiculopathy

Focal and segmental, dermatomal, myotomal

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Temporal profile of radiculopathy

Acute, subacute, or insidious depending on the cause

Highly variable

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Posteriolateral herniation

Disc impinges on lateral portion of dorsal or ventral root or proximal spinal nerve

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Far lateral herniation

Near the intervertebral foramen impinging on both dorsal and ventral root

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Central herniations

Common in lumbar vertebrae, impinges on multiple roots (cauda equina)

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Disc of herniation usually impinges on what

Root of adjacent level #

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Local manipulation and radical are pain or paresthesia

Straight leg raises produces traction on roots. Unaffected leg with symptomatic leg down.

Induced pain is a sign of local mass compressing roots

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Compression or irritation of descending roots. Same range of various causes as with radiculopathy at more rostral levels.

Cauda equina syndrome

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Motor deficits of caudal equina syndrome

Depend on whihc root levels are affected (L1-S4)

Causes saddle anesthesia (S2-S5)

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Infection via nerve terminals of DRG sensory neuron, retrograde transport to cell body

Herpes zoster

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How does herpes zoster initiate pain

Viral proliferation irritates neuron, alters firing pattern, spontaneous pain

Cutaneous blisters in dermatome

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What’s the difference between dermatome map and cutaneous nerve

Dermatome is related to the actual spinal nerve, cutaneous map is where the cutaneous sensory nerves innervate a certain area

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Damage to cervical, brachial, or lumbosacral plexus

Plexopathy

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Location of plexopathy

Damage to part of plexus- root, trunk, cords, major nerves near their proximal origins

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Etiology of plexopathy

Anesthesia
Paresthesia
Wide spread pain over multiple dermatomes
paresis of a muscle group
fasciculations may or may not
Focal distribution and likely multi segmental
acute, fluctuations depending on case

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Temporal profile of plexopathy

Acute, fluctant depedning on the cause

Location of mononeuropathy

Distal to plexus or not derived from a plexus (median or ulnar)

One nerve affected

Mononeuropathy

Presentation of mononeuropathy

- anesthesia (cutaneous map) - paresthesis (cutaneous map) - wide spread cutaneous nerve territory - paresis of a muscle group, multi segmental - fasciculations may or may not present

Distribution of mononeuropathy

Territory of one nerve, isolated muscle paralysis

Temporal profile of mononeuropathy

Acute, fluctuatant depending on the cause

Multiple nerves affected in a region affected

Polyneuropathy

Location of polyneuropathy

May distal nerves, often selective impact on large diameter axons (fine/discriminative touch, motor function)

Etiology of polyneuropathy

Auto-immune, mutation, toxins (lead)

Presentation of polyneuropathy

- sensory and motor | - paresis of several distal muscles, usually bilaterally

Distribution of polyneiropathy

Symmetrical and diffuse, distal extremities

Temporal profile of polyneuropathy

Acute, subacute, or insidious depending on the cause

Examples of polyneuropathy

Guillaine-Barre (autoimmune), Charcot Marie tooth (hereidatary), diabetic polyneuropathy (DM)

Autoimmune attack myelin sheath or oligodendrocyte. Detected as slowing of nerve conduction velocity

Demyelinating

Neurogenerative, genetic mutation? Detected as reduction in amplitude of nerve conduction

Axonopathy

Neuronopathy (axonopathy): sensory

Degenerative of neuronal cell bodies of sensory neurons in DRG

Neuronopathy (axonopathy): motor

Motorneurons of spinal cord

Location of diabetic polyneuropathy (DM)

Damage large diameter axons innervating distal extremities

Distribution of diabetic polyneuropathy

Diffuse and symmetrical due to glucose fluctuation

Presentation of diabetic polyneuropathy (DM)

Stocking and glove pattern (lower leg, hands, feet)

Temporal profile of diabetic polyneuropathy (DM)

Insidious/chronic

Guillaine-Barre syndrome (polyneuropathy)

Acute inflammatory demyelinating polyneuropathy (AIDP)

Etiology of Guillane-Barre syndrome

Often emerges after an infection resolves

Location of Guillane-Barre syndrome

Motorneuron function in distal legs, than arms, then facial (lower motorneurons)

Distribution of Gulliane-Barre

Symmetrical and diffuse Lower motor neurons

Presentation of guillane-barre

Motor weakness is more evident than sensory deficits

What is Charcot-Marie-tooth disease (polyneuropathy, axonopathy)

Genetic mutation causing degeneration of sensory and lower motor neurons

Distribution of Charcot Marie tooth disease

Diffuse and symmetrical

Presentation of Charcot Marie tooth disease

Flaccid weakness, impaired fine/discriminative touch and proprioceptive (sensory ataxia, lower motor neurons), normal pain and temperature

Location of Charcot Marie tooth disease

Preferentially impacts large diameter axons/fibers

Temporal profile of Charcot Marie tooth disease

Insidious/chronic, progressive

What kind of signs for neuropathies

Lower motor neuron signs

Distribution of deficits of neuropathies

Fits with nerve distribution territory

What is there an absence of in neuropathies

- spastic weakness and hyperreflexia - spinal cord signs (long tract signs or level down signs) - brainstem signs (CN signs ) - supratentorial signs (mental status, visual deficits)

Is stocking and glove level down

Neurological exam for peripheral nerve pathology and other disorders

Can narrow the localization of the problem; what general level of the CNS or PNS, what levels can be ruled out as the source of the problem?

Nerve conduction studies

Can measure nerve conduction velocity (testing for demyelinated nerves) or amplitude (testing for axonopathy).

What do you do to test for demyelinated nerves such as in MS?

Nerve conduction velocity

What do you do to test for axonopoathy

Nerve conduction amplitude

Stimulation electrode in muscle and recording of muscle response (motor unit potentials), measuring amplitude and whether firing pattern is continuous (normal recruitment of fibers) or intermittent (impaired muscle fiber recruitment)

Electromyopathy

Shows firing is continuous (normal) or increased (compensatory) but amplitude is reduced

Myopathic disease

Shows intermittent firing (impaired recruitment) but normal amplitude

Neuropathic disease

To detec auto immune forms of neuropathy

Antibody testing

To detect nerve or muscle disease

Genetic testing

To assess tissue and cellular signs of myopathy

Muscle biopsy

Nerve conduction studies

Measure distance and latency to compound motor action potential recorded from muscle, then calculate velocity (should be the same at all locations) also measure amplitude

Different amps

Axonopathy

Different velocity

Demyelination

How is the pattern different in NMJ than in neuropathy

NMJ disorders can: 1. No sensory loss (rare in neuropathies) 2. Some show fatiguable weakenss 3. Some may improve with sustained motor effort 4. DX techniques for NMJ vs neuropathies: electromyography

Myopathies vs neuropathies

1. No sensroy loss in myopathies 2. Diffuse weakness in myopathies vs focal/multifocal/diffuse neuropathies 3. Diagnostic techniques techniques for myopathies: EMG, muscle biopsy, genetic testing 4. Diagnostic techniques for neuropathies: nerve conduction, genetics, blood

What is there none of in neuropathies?

Sensory loss

What kind of weakness in neuropathies?

Diffuse weakness

Diagnostic techniques for myopathies

EMG, muscle biopsy, genetic testing

Diagnostic techniques for neuripathies

Nerve conduction, genetics, blood

Peripheral Nerve Pathology Flashcards

(78 cards)