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MSK II Exam II > Peripheral Neuropathies > Flashcards

Peripheral Neuropathies Flashcards

1
Q

Acquired peripheral neuropathies may arise from a variety of causes including metabolic, endocrine, infectious, immune-mediated, deficiency states, toxins, drugs, vascular, paraneoplastic manifestations, or idiopathic causes.

What are some common metabolic/endocrine causes of peripheral/polyneuropathies?

A

Diabetes mellitus

Thyroid disease

Uremia

Porphyria

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2
Q

Acquired peripheral neuropathies may arise from a variety of causes including metabolic, endocrine, infectious, immune-mediated, deficiency states, toxins, drugs, vascular, paraneoplastic manifestations, or idiopathic causes.

What are some infectious causes of polyneuropathies?

A 
Mononucleosis
Hepatitis
Lyme disease
HIV
Leprosy
Syphilis
Herpes zoster
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3
Q

Acquired peripheral neuropathies may arise from a variety of causes including metabolic, endocrine, infectious, immune-mediated, deficiency states, toxins, drugs, vascular, paraneoplastic manifestations, or idiopathic causes.

What are some immune mediated causes?

A

GBS, CIDP, Miller Fisher

Multifocal motor neuropathy

Paraproteinemic (monoclonal gammopathy)

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4
Q

Acquired peripheral neuropathies may arise from a variety of causes including metabolic, endocrine, infectious, immune-mediated, deficiency states, toxins, drugs, vascular, paraneoplastic manifestations, or idiopathic causes.

What are some deficiency states that may play a role in developing a polyneuropathy?

A

B1, B6, B12, E, Copper

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5
Q

Acquired peripheral neuropathies may arise from a variety of causes including metabolic, endocrine, infectious, immune-mediated, deficiency states, toxins, drugs, vascular, paraneoplastic manifestations, or idiopathic causes.

What are some toxins that may cause peripheral neuropathy?

A

Alcohol

Metals: Pb, As, Hg, Th

Organic compounds: n-hexane, organophosphates

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6
Q

Acquired peripheral neuropathies may arise from a variety of causes including metabolic, endocrine, infectious, immune-mediated, deficiency states, toxins, drugs, vascular, paraneoplastic manifestations, or idiopathic causes.

What are some drugs that may cause polyneuropathy?

A

Vinca alkaloids (vincristine —> polyneuropathy in 100% of pts)

Phenytoin
Isoniazid
Amiodarone
Cis-platinum
Nitrofurantoin
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7
Q

_____ deficiency causes a peripheral neuropathy that affects both the corticospinal tracts (+babinski) and dorsal columns (lose DTRs, neuropathy) of the spinal cord

A

B12

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8
Q

Acquired peripheral neuropathies may arise from a variety of causes including metabolic, endocrine, infectious, immune-mediated, deficiency states, toxins, drugs, vascular, paraneoplastic manifestations, or idiopathic causes.

What are some conditions associated with vascular causes of peripheral neuropathy?

A

RA
SLE
Polyarteritis nodosa

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9
Q

Acquired peripheral neuropathies may arise from a variety of causes including metabolic, endocrine, infectious, immune-mediated, deficiency states, toxins, drugs, vascular, paraneoplastic manifestations, or idiopathic causes.

Of the above, ________ causes are associated with pure sensory neuropathy (dorsal ganglionopathy)

A

Paraneoplastic

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10
Q

Pure sensory polyneuropathies are rare. In these cases there are 2 classifications to be considered: Sensory ganglionopathy and small-fiber neuropathy

What are 2 underlying etiologies of a sensory ganglionopathy?

A

Paraneoplastic (search for occult malignancy)

Toxins (platinum based chemotherapeutics)

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11
Q

Pure sensory polyneuropathies are rare. In these cases there are 2 classifications to be considered: Sensory ganglionopathy and small-fiber neuropathy.

What are the clinical features of a small-fiber neuropathy in terms of pain, temperature, light touch, reflexes, and strength?

A

Pain and temperature affected

Light touch, proprioception, reflexes, and strength are preserved!

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12
Q

Signs and symptoms of small fiber polyneuropathy

A

Signs — decreased pin-prick and temp sensation, dysesthesias to light touch. Normal strength, reflexes, proprioception, vibratory sensation

Symptoms — pain, “burning” dysesthesias, paresthesias, temperature sensation abnormalities

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13
Q

What are EMG findings with small fiber polyneuropathy? How is the diagnosis confirmed?

A

EMG/NCV is normal!

Dx based on skin biopsy — shows decreased epidermal nerve fiber density

[EMG is normal because small fibers are unmyelinated, and EMG only detects abnormalities of myelinated fibers]

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14
Q

Most common identifiable cause of neuropathy in the US

A

Diabetes mellitus

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15
Q

What are the different forms of polyneuropathy seen in DM?

A

Distal symmetric sensorimotor neuropathy (“stocking and glove”) — most common

Cranial neuropathy (CN III, VI, VII)

Mononeuropathy (carpal tunnel, etc)

Mononeuropathy multiplex

Autonomic neuropathy

Lumbosacral plexopathy (diabetic amyotrophy)

Radiculopathy

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16
Q

Charcot Marie Tooth is a hereditary motor sensory neuropathy; what is the inheritance?

A

Autosomal dominant

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17
Q

Differentiate Hereditary Motor Sensory Neuropathy type I vs. type II in terms of major pathologic feature and clinical presentation

[HMSN = Charcot-Marie-Tooth]

A

Type I = Most common; Demyelinating is major feature. Onset 1st or 2nd decade; often see difficulty walking or running, distal symmetric atrophy, arreflexia, mild sensory loss, skeletal deformities (pes cavus, hammer toes, scoliosis)

Type II = Axonal loss is major feature. Onset in adulthood; distal symmetric atrophy, arreflexia, mild sensory loss

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18
Q

EMG findings with HMSN type I vs type II

A

Type I EMG — slowling of motor nerve conduction velocities (i.e., demyelination)

Type II EMG — normal or nearly normal motor nerve conduction velocities (i.e., axonal loss

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19
Q

Hereditary polyneuropathy caused by alpha galactosidase deficiency

A

Fabry’s disease

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20
Q

Hereditary polyneuropathy due to alrylsulfatase A deficiency

A

Metachromatic leukodystrophy

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21
Q

Hereditary polyneuropathy due to deficiency in HDL

A

Tangier disease

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22
Q

Refsum’s disease is a hereditary polyneuropathy also known as _______ _____storage disease

A

Phytanic acid

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23
Q

Hereditary polyneuropathy due to defect in heme biosynthesis

A

Porphyria

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24
Q

Globoid cell leukodystrophy, abetalipoproteinemia (bassen-kornzweig syndrome), and familial amyloid neuropathies are __________

A. Acquired polyneuropathies
B. Acquired mononeuropathies
C. Hereditary mononeuropathies
D. Hereditary polyneuropathies
E. None of the above
A

D. Hereditary polyneuropathies

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25
Q

Acute/subacute ascending motor paralysis often following a viral syndrome (EBV, mycoplasma pneumoniae, C.jejuni enteritis), surgery, or immmunization

A

Guillain-Barre syndrome

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26
Q

Clinical features of GBS

A

Low back/leg pain possible at onset

Ascending usually symmetric weakness

Hypo or absent DTRs

No/minimal sensory symptoms or signs

Possible respiratory failure; autonomic involvement

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27
Q

Key lab findings in GBS involving CSF and NCVs

A

CSF: albumino-cytologic dissociation (increased protein, normal cell count, normal glucose)

NCVs: slow conduction velocity, focal conduction block, prolonged F-waves

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28
Q

Treatment for GBS

A

General supportive care with attention to: swallowing, respiration, cardiovascular support, infection, DVT

Direct treatment with plasma exchange or IVIG

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29
Q

Prognosis of GBS

A

25% need mechanical ventilator support

90% recover in weeks to months — 5-10% develop chronic form

Death in 4-10%

Persistent disability in 20%

Persistent fatigue in 67%

Poor prognosis is associated with NCV/EMG findings of low amplitude motor nerve responses and/or denervation as this implies axonal involvement

30
Q

Guillain-Barre Syndrome variant characterized by triad of ophthalmoplegia, ataxia, and arreflexia, as well as facial weakness, dysarthria, dysphagia, and antibodies to GQ1b and GT1a

A

Miller-Fisher Syndrome

31
Q

GBS variant characterized by GM1, GM1b, and GD1a antibodies

A

Acute motor axonal neuropathy (AMAN)

32
Q

GBS variant characterized by GM1, GM1b, and GM1a antibodies

A

Acute motor and sensory neuropathy (AMSAN)

33
Q

Similar to GBS but slower to evolve and more persistent (i.e., >2 mos); may occur de novo or as sequelae of GBS with progressive or relapsing course; 15% have a monoclonal Ab (IgM or IgG) and treatment includes IVIG, steroids, plasma exchange, and/or immunosuppressive agents

A

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

34
Q

Clinical features of multifocal motor neuropathy

A

Adults, M>F

Initially in distribution of a single nerve

Slowly progressive distal weakness of hands>feet

No sensory signs/symptoms, no UMN signs

35
Q

Lab findings in multifocal motor neuropathy (antibodies, EMG, CSF)

A

Elevated serum GM-1 antibody in 50-80%

EMG shows conduction block or other demyelinating features

CSF usually normal

36
Q

Types of neuropathy seen in HIV

A

Distal symmetric polyneuropathy

Acute inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy

37
Q

________ = dysfunction of the nerve root caused by structural or nonstructural conditions

A

Radiculopathy

38
Q

________ refers to the skin area supplied by a single spinal nerve root

A

Dermatome

39
Q

________ refers to the muscle group supplied by a single spinal nerve root

A

Myotome

40
Q

________ refers to the area of bone supplied by single spinal nerve root

A

Sclerotome

41
Q

Most common levels involved with cervical radiculopathy

A

C5-6 = C6 nerve root compression

C6-7 = C7 nerve root compression

42
Q

Most common levels involved with lumbar radiculopathy

A

L4-L5 = L5 nerve root compression

L5-S1 = S1 nerve root compression

43
Q

For a C5 radiculopathy, where is the location of pain, sensory change, weakness, and DTR loss?

A

Pain = scapula, shoulder

Sensory =lateral arm

Weakness = shoulder abduction

DTR loss = possibly biceps, but that is more likely lost with C6

44
Q

For a C6 radiculopathy, where is the location of pain, sensory change, weakness, and DTR loss?

A

Pain = scapula, shoulder, prox arm

Sensory = 1st and 2nd digit; lateral arm

Weakness = shoulder abduction, elbow flex

DTR loss = Biceps +/- brachioradialis

45
Q

For a C7 radiculopathy, where is the location of pain, sensory change, weakness, and DTR loss?

A

Pain = scapula, shoulder/arm, elbow/forearm

Sensory = 3rd digit

Weakness = elbow ext, wrist ext, finger ext

DTR loss = triceps

46
Q

For a C8 radiculopathy, where is the location of pain, sensory change, weakness, and DTR loss?

A

Pain = scapula, shoulder/arm, medial forearm

Sensory = 4th and 5th digit

Weakness = finger abduction, finger flexion

DTR loss = finger flexors

47
Q

For a L4 radiculopathy, where is the location of pain, sensory change, weakness, and DTR loss?

A

Pain = antlat thigh, knee, medial calf

Sensory = medial calf

Weakness = hip flexion, knee extension

DTR loss = patella

48
Q

For a L5 radiculopathy, where is the location of pain, sensory change, weakness, and DTR loss?

A

Pain = dorsal thigh, lateral calf

Sensory = lateral calf, dorsum of foot

Weakness = hamstrings, foot dorsiflexion, inversion, eversion

DTR loss = none

49
Q

For an S1 radiculopathy, where is the location of pain, sensory change, weakness, and DTR loss?

A

Pain = post thigh, post calf

Sensory = postlat calf, lateral foot

Weakness = hamstrings, foot plantarflex

DTR loss = achilles

50
Q

Dermatome landmarks for C6, C7, C8

A

C6 = thumb/index finger

C7 = middle finger

C8 = fourth/fifth finger

51
Q

Dermatome landmarks for T1, T4, T10

A

T1 = medial forearm

T4 = nipple line

T10 = umbilicus

52
Q

Dermatome landmarks for L1, L4, L5

A

L1 = inguinal

L4 = medial calf

L5 = lateral calf

53
Q

With a brachial or lumbosacral plexopathy, routine nerve conduction studies are often not adequate to make the diagnosis. ______ nerve action potentials are abnormal (vs. radiculopathy). Paraspinal muscles must be examined. _______ and _______ muscles may identify more proximal lesions, so in these cases radiculopathy should be included in the differential

A

Sensory
Rhomboids
Serratus anterior

54
Q

Causes of brachial plexopathy include compression/stretch (CABG), inflammatory/idiopathic (parsonage-turner), radiation injury, neoplastic, traumatic injury, and ischemia.

How do you differentiate between radiation injury and neoplastic process as the cause of a brachial plexopathy?

A

Radiation —> upper trunk, lateral cord, PAINLESS

Neoplastic —> medial cord, PAINFUL

55
Q

Inflammatory/idiopathic brachial plexopathy characterized by severe pain in shoulder area followed within a few days by weakness and atrophy (as pain subsides); usually involving muscles of shoulder girdle. Spontaneous recovery occurs in 6-18 mos

A

Parsonage-turner syndrome

56
Q

Peripheral nerve disease affecting sensory nerves does NOT typically manifest with loss of sensation. Positive findings more likely include _________ (if secondary to large myelinated fiber disease) or ______ (if secondary to small unmyelinated fiber disease)

A

Paresthesias; pain

57
Q

Symptoms of peripheral nerve disease affecting motor nerves

A

Distal weakness

Cramps

Muscle fasciculations (twitching)

Atrophy

Decreased DTRs

Reduced tone

[note that peripheral nerve disease of motor nerves does not result in weakness, fatigue, areflexia, hypotonia, or deformity]

58
Q

_____ nerve mononeuropathy is characterized by sensory loss involving medial palmar surface of lower forearm and palm, thenar eminence, thumb, and adjacent 2.5 fingers

A

Median

59
Q

Clinical features of median mononeuropathy due to pronator syndrome

A

Insidious onset of diffuse/dull ache about the proximal forearm

Pain exacerbated with forced forearm pronation

Easy fatigue of forearm muscles

Diffuse numbness of the hand mostly involving the 2nd-3rd fingers

Absence of nocturnal awakening d/t pain or numbness

60
Q

Nerve conduction and needle EMG results with median mononeuropathy d/t anterior interosseous syndrome

A

Nerve conduction: routine median and ulnar studies are normal

Needle EMG — abnormalities in FPL, FDP, PQ, while other median, medial cord, C8 mm are normal

61
Q

Common sites that cause ulnar mononeuropathy

A

Axilla

Elbow — between medial epicondyle and olecranon

Cubital tunnel — b/w tendinous arch of FCU

Wrist — Guyon’s canal

62
Q

With _____ mononeuropathy at the elbow, EMG may show abnormalities in 1st dorsal interosseous m., abductor digiti minimi m., adductor policis m., flexor carpi ulnaris m., and flexor digitorum profundus m.

A

Ulnar

63
Q

What is Froment Sign?

A

Utilization of accessory hand muscles to grip sheet of paper — indicates ulnar neuropathy

64
Q

Common sites causing radial mononeuropathy

A

Axilla — crutches

Humerus/spiral groove — saturday night palsy (MOST COMMON)

Supinator (posterior interosseous branch)

Wrist (superficial radial sensory branch)

65
Q

Radial nerve damage leads to readily recognizable ___ ___that results from paresis of the extensor muscles of the wrist, finger, and thumb

A

Wrist drop

66
Q

Clinical features of radial mononeuropathy d/t spiral groove compression (saturday night palsy)

A

Weakness of wrist and finger extension

Elbow extension (triceps) and brachioradialis SPARED

+/- sensory loss dorsal thumb web

[note: radial motor and sensory studies often normal; EMG findings in extensors of wrist and digits and perhaps brachioradialis]

67
Q

What is the neuropathy:

Weakness of foot dorsiflexion and eversion. Weakness of toe extension. Sensory loss dorsum of foot, +/- lateral calf

A

Peroneal mononeuropathy at fibular head

68
Q

General blood tests performed to evaluate disease of peripheral nerves

A 
CBC
CMP
Fasting BG
ESR
ANA, RF
Thyroid function
Serum protein electrophoresis
Immunoelectrophoresis
B12/Folate

[more specific tests based on hx and PE may include lyme Ab titer, ANCA, Anti-MAG, anti-GM1, Anti-GQ1b, Hu antibody]

69
Q

T/F: EMG/NCV rarely leads to a specific diagnosis. The primary utility of these tests is to broadly classify into axonal or demyelinating disease

A

True

[exceptions are GBS, CMT1, and MMN]

70
Q

Skin biopsy is used to diagnose what type of neuropathy?

A

Small fiber neuropathy

MSK II Exam II (10 decks)

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