Peripheral Nervous System - Sachen Flashcards by Andrew Herrmann

3 layers of peripheral nerve connective tissue

Epineurium - whole nerve
- Supplied by vasa nervorum
Perineurium - fascicles
Endoneurium - fibers

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A-alpha fibers

Large, proprioception and somatic motor

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A-beta fibers

Large-ish, touch and pressure

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A-gamma fibers

Medium, muscle spindle motor

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A-delta fibers

Small-ish, pain/cold/touch

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B fibers

Small-ish, pre-ganglionic autonomics

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C fibers

Tiny, UNMYELINATED, pain/temp/reflexes, post-ganglionic sympathetics

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2 main fiber types in peripheral neuropathies (NOT including DM)

A-alpha

C fibers

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Parts of a peripheral nerve that can be affected (6)

Cell body
Nerve root
Axon
Myelin sheath
Connective tissue
Blood supply

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Wallerian degeneration

Sever a nerve –> distal degeneration

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Most common cervical nerve roots affected by a radiculopathy (w/ percentages)

Most common lumbosacral nerve roots affected (w/ percentages)

C7 = 60%
C6 = 25%

L5 = 50%
S1 = 45%

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Causes of radiculopathy

Structural - discs, osteophytes, tumors, etc

Non-structural - DM, infections (ex. WNV), etc

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Pain in shoulder
Loss of sensation in lateral arm
Weak shoulder abduction
Loss of biceps reflex

C5 radiculopathy

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Pain in shoulder
Loss of sensation in lateral arm and digits 1, 2
Weak shoulder abduction and elbow flexion
Loss of biceps +/- brachioradialis reflexes

C6 radiculopathy

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Shoulder/arm/forearm pain
Loss of sensation in 3rd digit
Weak UE extension muscles
Loss of triceps reflex

C7 radiculopathy

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Shoulder/arm/forearm pain
Loss of sensation in digits 4, 5
Weak finger abduction and flexion

C8 radiculopathy

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Pain in knee, anterior lateral thigh, medial calf
Loss of sensation in medial calf
Weak hip flexion, knee extension

L4 radiculopathy

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Pain in dorsal thigh, lateral calf
Loss of sensation in lat calf, dorsal foot
Weak hamstrings, anterior leg mm

L5 radiculopathy

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Pain in posterior thigh and calf
Loss of sensation in lateral calf and lateral foot
Weak hamstrings and posterior leg muscles

S1 radiculopathy

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Cervical nerve roots exit (above/below) the numbered vertebra

Above (C5 root btwn C4 & C5)

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Thumb/index finger

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Middle finger

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4th/5th finger

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Medial forearm

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Nipple line

Umbilicus

T10

Inguinal area

Medial calf

Lateral calf

Lateral foot and posterior calf

Medial thigh

Paresthesias and motor/reflex symptoms (pins and needles, numbness) are secondary to what fibers?

Large myelinated fibers

Pain and temp symptoms are secondary to what fibers?

Small unmyelinated fibers

4 types of pain symptoms w/ peripheral neuropathy (w/ definitions)

- Burning - Dysesthesia (pain on gentle touch) - Hyperalgesia (lower threshold to pain) - Hyperpathia (elevated threshold, but excessively felt)

6 motor symptoms w/ peripheral neuropathy

- Weakness - Cramps - Fasciculations - Atrophy - Decreased DTRs - Reduced tone

Paresthesia of half of 4th finger Paresthesia of ALL of 4th finger

Median nerve issue C8 radiculopathy

4 places for ulnar neuropathy

- Axilla (crutches) - Elbow (behind medial epicondyle) - Cubital tunnel - Guyon's canal (wrist)

Froment sign

Ulnar neuropathy - grabs piece of paper w/ flexed thumb IP joint

Wrist drop, can't extend fingers

Radial neuropathy - compression as it winds around humerus (saturday night palsy)

Most common entrapment neuropathy of LE Most common causes?

Peroneal (fibular) nerve -- at fibular head - Sick patient lying on side for long period of time - Sitting legs crossed

Distinguishing L5 radiculopathy and peroneal nerve neuropathy Other tip-offs to radiculopathy

Ankle inversion (post. tib. m) - Normal = Peroneal nerve - Abnormal = L5 Hip pain, back pain, thigh pain

Patient gets IM injection in butt...most common neuropathy? How to avoid?

Sciatic Inject in UPPER-OUTER quad.

Posterior dislocation of the hip...possible neuropathy?

Sciatic

Pregnant woman giving delivery in lithotomy position...possible neuropathy?

Femoral (inguinal ligament)

Patient has numbness and tingling along anterolateral thigh...neuropathy? Cause?

Lateral femoral cutaneous Tight clothing or weight gain around waist

Pain down lateral thigh, foot-drop, absent S1 reflex

Sciatic neuropathy

Foot drop, weak eversion, lost sensation to dorsum of foot

Peroneal (fibular) neuropathy

Weak knee extension, absent patellar reflex

Femoral neuropathy

Sensory loss in sole of foot

Posterior tibial neuropathy (tarsal tunnel syndrome)

Peripheral neuropathies can involve ___, ___, ___, and ___

Motor Sensory Cranial nerves Autonomics

Peripheral polyneuropathy presents where?

Symmetric stocking-glove distribution of symptoms

3 big categories of KNOWN causes of peripheral neuropathies

- Hereditary - Toxins/meds - DM

4 metabolic/endocrine causes of peripheral neuropathy

DM, hypothyroid, uremia, porphyria

Patient w/ severe abdominal pain, can't find abdominal cause or psychiatric cause. Diagnosed by neurologist.

Porphyria

Infectious causes of peripheral neuropathy (7)

Mono, hepatitis, Lyme disease | HIV, leprosy, syphilis, VZV

Immune-mediated causes of peripheral neuropathy (4)

Guillan-Barre Chronic inflam. demyel. poly. Multifocal motor neuropathy Paraproteins (monoclonal gam)

Vitamin deficiency causes of peripheral neuropathy (5)

B1, B6, **B12, E, Copper

Toxic causes of peripheral neuropathy

Alcohol Heavy metals Organic compounds

Vasculitic causes of peripheral neuropathy

RA, SLE, PAN

``` Child/teenager Difficulty walking/running Lower leg atrophy and foot deformities Skeletal deformities Arreflexia, mild sensory loss ``` Inheritance?

Charcot-Marie-Tooth type 1 Autosomal dominant

How does CMT type 2 differ from type 1? (2)

- Adult onset | - Axonal loss, but normal nerve velocities

Acute/subacute ascending motor paralysis, recent illness or surgery or immunization Infectious causes? (5)

Guillan-Barre EBV, Mycoplasma pneumonia, C. jejuni, HIV, Hodgkin's

Treating Guillan-Barre

Supportive (swallowing, respiratory, infection, DVT) Plasmapheresis, IVIg

Bad symptoms of G-B that must be watched for and treated

Respiratory difficulty, sudden drops in BP

Poor prognosis in G-B

Axonal damage

Miller-Fisher Syndrome -- what is it? - Symptoms? - Labs?

5% variant of G-B - Ophthalmoplegia, ataxia, arreflexia - GQ1b antibody

G-B that persists for 2+ months, symmetric distal involvement, progressive Treatment?

CIDP **IVIg, steroids, plasma exchange

Adult w/ slowly progressive distal weakness of hand, no sensory or UMN symptoms. Slowly involves other nerves. GM-1 antibody. Treatment?

Multifocal motor neuropathy IVIg

Possible presentations of DM neuropathy (7)

- Distal sensorimotor - Cranial nerve (3, 6, other) - Mononeuropathy (ex. CT) - Mono multiplex - Autonomic - Lumbosacral plexopathy - Radiculopathy

DM CN3 palsy vs. Compression CN3 palsy

``` DM = normal light reflex Comp = bad light reflex ```

HIV neuropathy presentations (3)

- Distal symmetric poly - Guillan-Barre - CIDP

``` aANCA Anti-MAG antibodies Anti-GM1 antibodies Anti-GQ1b antibodies Hu antibody ```

- Systemic vasculitis - MGUS - Multifocal motor neuropathy - Miller Fisher syndrome - Carcinoma sensory neurop

Important blood tests to get in peripheral neuropathy

CBC, chemistry, Glc, ESR, antibodies SPEP -- looking for spikes B12/Folate

EMG/NCV can be used to distinguish what? Specific diagnoses with this?

Axonal vs. demyelinating neuropathy GBS, CMT, MMN

Peripheral Nervous System - Sachen Flashcards

(74 cards)