Chapter 27: Diseases of Peripheral Nerves

Question 1

Why is the peripheral nerve dysfunction caused by neuronopathies equally likely to affect proximal and distal parts of the body?

Answer 1

Damage at the level of neuronal cell body

Question 2

Which structures are injured in the CMT2 variant of CMT disease and when does it present?

Answer 2

Axonal injury; typically severe w/ early childhood onset

Question 3

Which type of neuropathy is seen with lepromatous leprosy (Hansen Disease) and which sensory fibers will be lost?

Answer 3

• Symmetric polyneuropathy affected cool distal extremities and face
• Involves pain fibers, loss of sensation = injury; since pt’s are rendered unaware of injurious stimuli –> large traumatic ulcers

Question 4

If VZV is reactivated it travels along sensory nerves and leads to what?

Answer 4

Painful, vesicular skin eruption (shingles) in a sensory dermatomal distribution

Question 5

Morphologically what is the most prominent lesion seen in Guillain-Barre Syndrome?

Answer 5

Segmental demyelination affecting peripheral nerves

Question 6

Upon sural nerve biopsy in patient with Chronic inflammatory Demyelinating Poly(radiculo)neuropathy what is a characteristic finding?

Answer 6

Onion-bulbs: excessive proliferation –> multiple layers of Schwann cells wrap around an axon like the layers of an onion

Question 7

Demyelinating forms of Charcot-Marie-Tooth (CMT) disease are associated with what morphological features?

Answer 7

• Demyelination and remyelination including Schwann cell hyperplasia —> Onion-bulb formation
• Hyperplasia may be so severe that involved nerve is palpably enlarged

Question 8

Which type of neuropathy is the most common paraneoplastic form and which malignancy is it most commonly associated with?

Answer 8

Sensorimotor neuronopathy in setting of Small cell lung cancer = most common

Question 9

Which nerve is affected in Morton neuroma and what histologic finding is seen?

Answer 9

• Interdigital nerve at intermetatarsal sites –> foot pain; “walking on a marble”
• Histologically = perineural fibrosis

Question 10

What are the primary targets of damage in demyelinating neuropathies?

Answer 10

Schwann cells w/ their myelin sheaths

Question 11

Clinical presentation of Guillain-Barre Syndrome is dominated by what signs/sx’s; what characteristic CSF finding will there be?

Answer 11

• Ascending paralysis and areflexia
• DTR’s lost early in the process
• ↑ CSF protein levels w/ little or no CSF pleocytosis (inflammatory cells remain confined to the roots

Question 12

How is Chronic inflammatory Demyelinating Poly(radiculo)neuropathy treated?

Answer 12

Glucocorticoids + IVIg + plasmapheresis

Question 13

Which dermatomes are commonly affected by VZV reactivation; what kind of damage is seen?

Answer 13

• Thoracic or trigeminal nerve dermatomes
• Neuronal destruction and loss of affected ganglia
• Axonal degeneration of periphral nerves after death of sensory neurons

Question 14

What is a a distinctive presentation of neuropathy associated with monoclonal gammopathies?

Answer 14

POEMS: Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal gammopathy, and Skin changes

Question 15

In lepromatous leprosy (Hansen Disease) Schwann cells are invaded by Mycobacterium leprae and what pattern of peripheral nerve damage will be seen?

Answer 15

Segmental demyelination and remyelination + loss of both myelinated and unmyelinated axons

Question 16

Familial amyloid polyneuropathies are mainly due to germline mutations in which gene?

Answer 16

Transthyretin gene

Question 17

Focal destruction of which neuronal structures may be seen with reactivation of VZV?

Answer 17

Large motor neurons in anterior horn or cranial nerve nuclei

Question 18

“Saturday night palsy” is due to compression of which nerve?

Answer 18

Radial nerve in the upper arm

Question 19

Prevalence of peripheral neuropathy associated with diabetes is dependent on what?

Answer 19

Duration of the disease

Question 20

2/3’s of Guillain-Barre Syndrome cases are preceded by what; which etiologies have been implicated?

Answer 20

• Acute, influenza-like illness
• Campylobacter, CMV, EBV, and Mycoplasma penumoniae, or prior vaccination

Question 21

Other than peripheral neuropathy, what is another manifestation of diabetic nervous system dysfunction that is often seen?

Answer 21

Autonomic dysfunction: postural hypotension, incomplete bladder emptying (↑ infections) and sexual dysfunction

Question 22

Mononeuritis multiplex describes a disease process that damages several nerves in a haphazard fashion and is commonly due to what?

Answer 22

Vasculitis i.e., polyarteritis nodosum

Question 23

Which painful nodule composed of non-neoplastic haphazard whorled proliferation of axonal processes and assoc. Schwann cells results from failure of axons to find their distal target during regeneration ?

Answer 23

Traumatic neuroma aka “pseudotumor”

Question 24

Characteristic “stocking and glove” distribution of sensory deficits is seen with what anatomic pattern of peripheral neuropathies?

Answer 24

Polyneuropathies

Question 25

Which 2 features of Chronic inflammatory Demyelinating Poly(radiculo)neuropathy distinguish it from Guillain-Barre?

Answer 25

**Time course** (presence at least **2 months**) and **_response_** to **steroids**

Question 26

What is the electrophysiologic hallmark of axonal neuropathies vs. demyelinating neuropathies?

Answer 26

- **Axonal neuropthay** = a _reduction_ in **signal _strength_** - **Demyelinating neuropathy** = slowed nerve **conduction** **_velocity_**

Question 27

Chronic inflammatory Demyelinating Poly(radiculo)neuropathy is characterized by what type of neuropathy?

Answer 27

**_Symmetrical_** mixed **sensorimotor polyneuropathy** that persists for **2 months** or **more**

Question 28

What are "positive sx's" associated with diabetic peripheral neuropathy?

Answer 28

**_Paresthesias_** and **_dyesthesias_** = **painful sensations**

Question 29

Diabetic peripheral neuropathy is characterized by a relative loss of which size and type of nerve fibers?

Answer 29

**_Small_** myelinated _and_ unmyelinated fibers

Question 30

How is Guillain-Barre Syndrome managed clinically?

Answer 30

**Plasmapheresis** and **IV Ig**

Question 31

More localized nerve involvement associated with granulomatous nodules in the dermis is characteristic of what form of leprosy?

Answer 31

**Tuberculoid leprosy** = **T_H1 (cell-mediated) response**

Question 32

Uremic neuropathy seen in setting of renal failure is a distal, symmetric neuropathy often associated w/ what signs and sx's?

Answer 32

**Muscle cramps** + **distal dysesthesias** + ↓ **DTRs**

Question 33

What is the _most common_ acquired inflammatory peripheral neuropathy?

Answer 33

**_Chronic_** inflammatory **Demyelinating** **Poly(radiculo)neuropathy**

Question 34

Histologic features of Guillain-Barre Syndrome are characterized by what?

Answer 34

**_Inflammation**_ and _**demyelination_** of **spinal nerve roots** and **peripheral nerves** = **_radiculoneuropathy_**

Question 35

Peripheral nerve dysfunction as a result of Diptheria is due to what; what are the early sx's and later findings?

Answer 35

- Result of diptheria **exotoxin** - **_Early_** loss of **_proprioception_** and **_vibratory sensation_** - **Acute peripheral neuropathy** assoc. w/ **prominent bulbar** and **respiratory m. dysf.**

Question 36

What is the most common pattern of peripheral neuropathy seen with Diabetes?

Answer 36

**Ascending distal _symmetric_ sensorimotor polyneuropathy**

Question 37

What is the most common subtype of hereditary motor and sensory neuropathy (CMT) disease, what is the inheritance pattern, when and how does it present?

Answer 37

- **CMT1** = group of **autosomal _dominant_** disorders - Presents in **_2nd decade_** w/ _slowly_ progressive **distal demyelinating motor** and **sensory** neuropathy

Question 38

Biopsies of the affected peripheral nerves/arterioles in diabetes will show what finding and with what stain?

Answer 38

**Endoneurial arterioles** show _thickening_, hyalinization, and intense **PAS-(+)** of their walls + extensive _reduplication_ of basement membranes