Peripheral Nerves and Skeletal Muscles Pathology (Hertz) - MT Flashcards Preview

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Flashcards in Peripheral Nerves and Skeletal Muscles Pathology (Hertz) - MT Deck (105)
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Nerve conduction studies measure what?

Velocity of conductino of the nerve, dependent on Myelin component


Nerve biopsies usually are taken from what nerve?

sural nerve


CSF analysis measures what 3 things in the fluid?

white cells, protein, glucose


Serum chemistry for muscle pathology is?


serum creatinine phosphate kinase


1. Where is this disease process located?

2. What is the process called that leads to the appearance of this leg?



1. Disease process located at anterior horn in the cord

2. Denervation atrophy



What does Pic A and Pic B in this EM show?


pic A shows loosening of myelin layer in degenerating axon lower left. Normal axon upper right


pic B shows vacuoles of lipids derived from degenerating myelin


You are seeing a patient who reports having an influenza like illness a month ago, but has since recovered. However, he also reports burning himself on the stove top by accident while cooking and says " I didn't feel the pain, I only pulled my hand away when I smelled my skin burning". He now presents with ascending paralysis and areflexia.

1. What mechanism most likely mediated the  neuropathy found in this patient?

2. What are 5 significant epidemiologic associations with this pathology (4 infections + 1 other)?

1. Immune mediated demyelinating neuropathy


2. Campylobacter jejuni, CMV, EBV, Mycoplasma pneumoniae infections

and prior vaccination all have significant association with Guillain barre syndrome



What are the black dots in this nerve biopsy?

What do they cause?

Single black dots are lymphocytes


demyelination in Guillain barre syndrome.

Chronic inflammation


You are trying to diagnose a patient's suspected guillain barre syndrome.


What study would you order besides a CSF analysis?

What would it show you?

Why would it show you this?

1. Nerve conduction study


2. decreased conduction velocity


3. multifocal destruction of myelin segments in many axons within a nerve


What would be elevated in a CSF analysis in guillain barre syndrome?

why (x2)?

- protein levels elevated

- d/t inflammation and altered permeability of microcirculation within spinal roots as they traverse the subarachnoid space


On physical exam, what normal function dissapears rather early on in a patient afflicted with Guillain Barre syndrome?

Deep tendon reflexes


The most common chronic acquired inflammatory peripheral neuropathy is?

Chronic inflammatory demyelinating poly radiculo neuropathy


This images indicates what histologic feature?

Onion bulb neuropathy in figure B and a normal axon in figure A

found in chronic inflammatory demyelinating polyradiculoneuropathy


Chronic inflammatory demyelinating polyradiculoneuropathy is characterized by what kind of neuropathy that persists more than 2 months?

symmetrical mixed sensrimotor polyneuropathy


Neuropathies associated w/ systemic autoimmune diseases can be caused by what diseases x3?

- Rheumatoid arthritis

- Sjogren syndrome

- Systemic lupus erythematosus


Neuropathy caused by SLE is of what type?






distal sensory



Peripheral nerve damage can be caused by what blood vessel pathology?



infectious neuropathies can arise from what diseases? x5

- Leprosy (hansen disease)


- Diphtheria

- Lyme disease

- Varicella zoster virus


What causes this lesion?

Tick bite that causes lyme disease


What causes this?




Histology would show granulomatous patterning if these papules were biopsied. What causes them?

Leprosy (hansen disease)


What is the most common cause of peripheral neuropathy?



This is an EM from a diabetic patient with peripheral neuropathy. What does it show?

Loss of myelinated fibers, a thinly myelinated fiber.


A patient presents with increasing loss of balance, loss of pain sensation, HemA1C >10, and also chronic skin ulcers. He wants you to prescribe a medication that helps him get an erection.


What disease does this patient have and why does he want this medication?


Diabetes mellitus


Diabetic neuropathy can affect the autonomic nervous system

It affects about 30% of individuals with DM

almost always in conjunction to distal sensorimotor neuropathy.


diabetic autonomic neuropathy can present with protean sx like? x3

1. postural hypotension

2. incomplete bladder emptying

3. sexual disfunction


What are some metabolic, hormonal, and nutritional causes of neuropathies besides the diabetic neuropathy? x4

1. Uremic neuropathy

2. Thyroid dysfunction

3. Vitamin B12 deficiency

4. Deficiency of Vitamin B1 thiamine, and vitamine B6 pyridoxine, folate, vit E, copper, zinc


This man is sweating salt.


What is the result of the distal symetric neuropathy?

- He is in renal failure


- muscle cramps, distal dysesthesias, diminished DTR


Question on picture

vit B1 thiamine deficiency


Toxic neuropathy can arise from exposure to industrial or environmental chemicals, bio toxins, or therapuetic drugs. What are 3 general categories of things that this includes?

1. alcohol

2. heavy metals

3. organic solvents


Paraneoplastic neuropathies are commonly associated with which type of cancer?

small cell lung cancer


paraneoplastic neuropathy most commonly affects motor or sensory function?

both, sensorimotor neuropathy



cancer may commonly cause mononeuropathy d/t direct infiltration or.....



Neoplastic B cells may cause demyelination leading to peripheral neuropaty because they can.....

Secrete monoclonal Immunoglobulins or paraproteins that damage nerve. Specifically IgM antibodies



What does this histo slide show?

What type of neuropathy does this cause?

small cell lung cancer

Paraneoplastic neuropathy


inherited peripheral neuropaties usually present in what patient population?



Inherited mixed sensory and motor neuropathies are known as?

Charcot marie tooth (CMT) disease


CMT disease is byfar the most common inherited peripheral neropathy. This disease is characterized by what distal limb PE signs/symptoms (x3)?

1. distal muscle atrophy (perineal atrophy)

2. sensory loss

3. foot deformities (pes cavus)


 A person with this feature could also have what other finding on PE d/t loss of sensory function?

ulcers on feet and hands d/t loss of sensory function


This is a congo red stain of a nerve biopsy.

What is the pink?

What does it cause in nerves?

- amyloid

- Familial amyloid polyneuropathy


Diseases that impair the NMJ usually present with what cardinal sx?

painless weakness


The most common cause of NMJ protein inhibition leading to disruption of neuromuscular transmission is?


(like the ones found in myasthenia gravis)


Autoantibodies in Myasthenia gravis target what structure?

ACh receptors on the post synaptic motor end plate


In the presence of anti ACh receptor autoantibodies, what other pathology should you look for due to its high association with the latter?

Thymic abnormalities


10% of pathients with myasthenia gravis have this. What is it?

An additional 30% have a different abnormality of the same organ called?

- thymoma, a tumor of thymic epith cells

- thymic hyperplasia


A patient presents with fluctuating muscle weakness with exertion, diplopia, and ptosis.

You suspect what disease?

Diagnosis of this disease is based on what lab findings? x2

- Myasthenia Gravis

- Identification of autoantibodies

- electorphysiologic studies revealing a decrement in muscle response w/ repeated stim


First line treatment agents for Myasthenia gravis are?

AChase inhibitors like Neostigmine, pyridostigmine, ambenonium (doesn't cross BBB)


Dr. Linger integration question:

D/t the bradycardia / bronchospasm ADR risk associated with the edrophonium test to diagnose myasthenia gravis, another test was developed to diagnose.

What is this test?

How does it work?

- Ice pack on eyelid test for 2-3 min

- ice temporarily inhibits AChase enzyme activity, thus relieving ptosis


A patient presents with complaints of muscle weakness in the extremities, which improves in strength with repetitive stimulation.

- What disease is this?

- You test for antibodies that do what?

- You also check for what associated pathology, since about half the cases have it.


1. Lambert eaton myasthenic syndrome

2. antibodies block acetylcholine release by inhibiting presynaptic Ca2+ channels

3. Neuroendocrine carcinoma of the lung


Describe the cells you would find in the mass identified in this CT

small cells with big nuclei, and little to no cytoplasm

indicative of small cell carcinoma of da lung (oat cell carcinoma of the lung)


Match Myasthenia gravis and Lamber eaton myastenic syndrome to their respective figures in the pic


A self proclaimed doomsday prepper proudly brings out some of the jarred foods he has been preserving for the coming apocalypse to feed his guests at a dinner party. Some of his guests present to the ED the next day with worsening double vision, dysphagia, dry mouth, slurred speech and muscle weakness that starts in the shoulders and descends through the body.

- What is the organism most likely responsible for these sx?

- What gram properties and oxygen use status characterizes this organism?

- How does this organism cause the sx (name the condition too)?



1. Clostridium botulinum

2. gram positive anaerobic organism

3. Neurotoxin causing botulism


C. botulinum produces a neurotoxin that is popularly known as botox. This toxin acts at the NMJ by.......?


- this causes what sx? x6

blocking the release of ACh from presynaptic neurons


- double & blurry vision

- ptosis

- slurred speech

- dysphagia

- dry mouth

- muscle weakness (shoulders to all of body)


What is a curare?

common name for related muscle relaxants that block ACh receptors resulting in flaccid paralysis


This is an NADH stain of a skeletal muscle biopsy.

Why is this considered a normal looking biopsy?

Checker board pattern shows the even distribution of red and white muscle fibers.


What differs a neurogenic disease from a dermatomyositis in terms of nerve and muscle fiber distribution?

- clusters or groups of atrophic fibers are seen with neurogenic diseases


- Perifascicular atrophy is seen in dermatomyositis, damage to myfibers directly.


Neurogenic injuries lead to what occurence in regards to the organization of muscle fiber types?

What happens during the subsequent regeneration of these neuromuscular units?


Fiber type grouping

* same type of muscle fibers associated with a given nerve atrophy d/t denervation

* regeneration in distinct group types with loss of checkerboard patterning


Segmental myofiber degeneration and regeneration is seen when only part of a myofiber undergoes necrosis. This degeneration is associated with release of what detectable substance into the blood?

Cytoplasmic enzyme known as Creatine kinase

(marker of muscle damage, CPK)


The inflammatory myopathies we covered in this lecture are? x3

- polymyositis, dermatomyositis, inclusion body myositis


other immune mediated disorders that can cause myositis include? x4

*not as emphasized to just flip it.


systemic sclerosis


certain infectious agents


Que esta pasando en la imagen?

What is happening in the picture?

Lymphocytic invasion of the muscle fiber indicating an inflammatory myopathy


A patient presents with proximal muscle weakness and skin changes. In your mind, you think of an autoimmune disease which:

- Targets what structures?

- This leads to?

- what disease is this?

- small blood vessels

- muscle injury

- Dermatomyositis


- What antibody is associated to the heliotropic rash on this woman's face?

- these antibodies are directed against?

- What does the histology pic show? x2


1. Anti Mi2 antibodies

2. directed against helicase implicated in nucleosome remodeling

3. perifascicular atrophy of muscle fibers and inflammation 


You are looking over a patient's chart and see a description for a rash as "mechanic's hands". You also see that the patient has a history of non erosive arthritis, dermatomyositis, and interstitial lung disease.

- What antibodies do you suspect to be the cause of the above presentation?

- what do these antibodies target?


1. Anti Jo1 antibodies

2. target enzyme histidyl t-RNA synthetase


You are looking over a case report in which a juvenile patient had a paraneoplastic disease and was diagnosed with dermatomyositis.

- which antibody do you suspect this child has/had

- what is it directed against?


1. anti P155/P140

2. against transcriptional regulators


A patient you are seeing has recently been diagnosed with dermatomyositis. On his diagnostic visit, he had reported he had difficultiy rising from his chair and climbing steps.

- Why is this?

- If left untreated, what sx can he expect later on in the disease process?

- proximal muscles are affected first


- later on, fine movements controlled by distal muscles are affected.


Muscle damage is gauged with what tests in a patient with dermatomyositis?

- Electrophysiologic studies

- elevation of serum creatine kinase


What is a heliotrope rash?

What is a gottron papule?

What disease can characterized by both the above?

- heliotrope rash is lilac colored discoloration of upper eyelids associated with periorbital edema.


- Gottron papule is  scaling erythematous eruption or dusky red patch over knuckles, elbows, knees


- dermatomyositis


A patient diagnosed with dermatomyositis reports dysphagia.

Why is this?

- a third of the individuals with dermatomyositis have involvement of oropharyngeal and esophageal muscles.


A patient died of a rapidly progressive interstitial lung disease. In her final days, she had a hard time drawing the finer details in her paintings. What type of autoantibodies likely caused her condition?

Anti Jo 1 antibodies


directed against enzyme histidyl tRNA synthetase

associated with interstitial lung disease, non erosive arthritis, mechanic hand rash


What is shown on each pic?

A - heliotropic rash

B - mechanic hand rash

C - Gottron papules on knuckles

D - gottron papules on knees


A 40 y/o male presents with myalgia and weakness. You check for skin changes / lesions, but find none. Serum creatine kinase levels are elevated to 10x nml level (nml is between 60- 174 IU/L).

What is your diagnosis?



These muscles are usually affected in what inflammatory myopathy?

What type of cells would you find in the muscle biopsy surrounding the muscle fascicles diffusely?

- Polymyositis


- Cytotoxic CD8 Tcells and Macrophages with CD68 markers


A 69 y/o man presents with progressive and slow muscle weakness which has hindered his ability to walk up stairs and write. Serum creatine kinase is elevated. No skin rashes present.


What is your diagnosis?

Inclusion body myositis

most common inflammatory myopathy in patients older than 65 y/o

most severe in quads and distal upper extremities


This is a modified gomori trichrome stain of a muscle biopsy.

What does this tell you about how this patient will respond to the standard treatment protocol for inflammatory myopathies?

This patient will not respond to the standard first line treatments for dermatomyositis and polymyositis which include


Corticosteroids and Immunosuppressive drugs


This histology is of an inclusion body myositis


In addition to corticosteroid first line treatment drugs, Immunosuppressive agents are used to treat poly and dermatomyositises as 3rd line therapies.

How are the Immune suppresive drugs administered?

*name a couple


- administered intravenously IVIG


*rituximab, cyclophosphamide, cyclosporine (3rd line drugs)


You are treating a patient for hypercholesterolemia with simvastatin. What must you check in your patient? (occurs in 1.5% of statin users)

- serum creatine kinase levels must be checked

*statins can cause toxic myopathy


A patient with SLE on long term treatment presents with elevated serum creatine kinase levels. Her medication used to be an antimalarial agent.

What are two agents that she could be taking?

- chloroquine

- hydroxychloroquine


A patient who is diagnosed with hyperthyroidism has an elevated serum creatine kinase and muscle weakness.

What is the diagnosis?

What muscles are commonly affected in his condition?

- thyrotoxic myopathy


- proximal muscle weakness as acute or chronic


Alcohol can cause toxic myopathy.

If you really wanted to get a myopathy induced by alcohol, how would you drink your alcohol?

Binge drink it


A mother brings in her infant who presents with hypotonia and "floppy infant" sign. The mother has a history of muscular dystrophy as well.

- The most common muscular dystrophies are X-linked and stem from mutations that disrupt what?

disrupt function of large structural protein called Dystrophin


Duchenne and Becker muscular dystrophies are caused by?

X-linked mutations that disrupt the function of dystrophin gene


These are the stages of Ducheenne muscular dystrophy.

- What stage of the disease is demonstrated by each picture? (early/late)

- What are the histologic findings that demarkate each stage of the disease?

- early, early, late


- A = early younger age, fascicular muscle architecture is maintained but myofibers show variable size

- B = early IHC stain shows complete absence of membrane associated dystrophin

*normal is big pic, absent dystrophin in lower right box

- C = Late in disease shows pseudohypertrophy of lipid vacuoles



- The histologic picture shows what characteristic of duchenne muscular dystrophy?

- The western blot gel tests for dystrophin. Which lanes lanes represent normal dystrophin levels, Duchenne dystrophin levels, and Becker dystrophin levels?

- variable muscle fiber size characterizes duchenne muscular dystrophy


- normal dystrophin far right lane, Becker is middle lane with reduced dystrophin, Duchenne is left lane and has absent dystrophin


Boys with duchenne muscular dystrophy are normal at birth, very early motor milestones are met, but walking is often delayed. First indication of muscle weakness are clumsiness and inability to keep up with peers.


- What muscles are initially affected and weakened?

- Pseudohypertrophy with lipid vacuoles often also affects which muscles?


- Pelvic Girdle muscles are weakened first. Then extends to shoulder girdle


- Pseudohypertrophy affects lower leg muscles leading to enlargement and weakness in Lower limbs


Describe serum creatine kinase levels through the course of duchenne muscular dystrophy.

elevated in first decade of life d/t ongoing muscle damage, falls as disease progresses and muscle mass is lost


What does this pic show?

Pseudohypertrophy with lipid vacuoles distributed throughout muscle fibers


What does this child have difficulty doing?

gower sign, indicating muscular dystrophy


spinal muscular atrophy is a neuropathic disorder in which loss of ________ leads to muscle weakness and atrophy?

motor neurons


differential diagnosis of n infant with hypotonia should include?

- primary diseases of skeletal muscle

- abnormalities of brain

- neuronopathies


WHat is the medical term used to describe the children in the pictures.

The child has _________

generalized hypotonia


Why are some of the myofibers enlarged in this muscle biopsy of a child with spinal muscular atrophy?

Enlarged fibers are innervated myofibers that have undergone compensatory hypertrophy


A patient who has a history of congenital myopathy needs an airway during a surgery. The anesthesiologist in charge of intubation uses vecuronium instead of succinyl choline as the anesthetic agent because....

- he is concerned about what?

- What are the sx of this pathology?

- What causes these sx? (pathophys)

- Malignant hyperthermia (ion channel myopathy)


- Sx = tetany, excessive heat production, hypermetabolic state tachycardia, tachypnea, muscle spasms.


-  upon exposure to anesthetic succinyl choline, mutated Ryanodine (RYR1) receptor allows increased efflux of calcium from Sarcoplasmic reticulum leading to tetany and excess heat production


Three common types of periheral nerve sheath tumors are schwannomas, neurofibromas, and malignant peripheral nerve sheath tumors (MPNST).

- The vast majority of these tumors show evidence of differentiation in what cell type?


- Peripheral nerve sheath tumors are associated with what common familial tumor syndromes? x3

- Schwann cell differentiation


- Neurofibromatosis type 1, NF type 2, and Schwannomatosis


Schwannomas are:

1. malignant or benign tumors?

2. Show schwann cell differentiation and often arise directly from what?

3. This image indicates an over production of what?

4. The image indicates a loss of expression of what?

1. benign tumors

2. peripheral nerves

3. over productino of myelin

4. loss of NF2 gene product named MERLIN


- In picture A (top left),

what is the dense eosinophilic area known as and what is the pale area with hyalinized blood vessel known as?


- In picture B (top right),

What are these structures and what forms them?


*- In picture C (bottom left),

Plexiform neurofibroma is pictured, what characteristic is shown?


*- In picture D (bottom right),

Plexiform neurofibroma is pictured, this shows carrot shaving patterning made of what?

- pic A

dense eosinophilic area = Antoni A area

Pale area w/ hyalinized blood vessel = Antoni B area


- pic B

antoni A area with tumor cell nuclei aligned in palisading rows leaving anuclear zones and resulting in formation of structure termed Verocay bodies


*pic C

multiple nerve fascicles are expanded by infiltrating tumor cells


*pic D

bland spindle cells are admixed with wavy collagen bundles



This CT scan is from a man who has been diagnosed with a schwannoma and has  presented to the office with facial weakness, tinnitus and hearing loss.

- Why does this man complain of tinnitus and hearing loss?

- Why facial weakness?


most schwannomas cause sx by LOCAL COMPRESSION of involved nerve or adjacent structures


1. The Schwann cell tumor grows on the VESTIBULAR branch of the 8th nerve and can compress the nerve.


2. The schwannoma on the 8th nerve can grow so big it compresses the facial nerve (CN VII) thus causing facial weakness


A pathologist shows you a biopsy composed of neoplastic schwann clls mixed with perineurial like cells, fibroblasts, mast cells, and CD34+ spindle cells.


- Is this tumor mlignant or benign?

- What is it?

- what are the 3 subtypes of this tumor?

- benign


- Neurofibroma = nerve sheath tumor


- Superficial cutaneous, Diffuse, Plexiform


You biopsy a pedunculated nodule that is NF1 associated. You correctly identify it as what type of Neurofibroma?

Superficial cutaneous neurofibroma


You biopsy a mass from a large deep nerve root, which you identify as a neurofibroma. What subtype is it?

Plexiform neurofibroma


you see a large plaquelike elevation of skin on a patient. Upon examination of a biopsy you took from it, you identify that it is NF1 associated and a neurofibroma. what subtype is it?

diffuse neurofibroma


About half of these tumors arise in Neurofibromatosis type 1.

- What are they?

- They can transform into what?

- plexiform neurofibromas


- Malignant peripheral nerve sheath tumors (MPNSTs)


This tumor contains glandular, cartilaginous, osseus, and rhabdomyoblastic morphology.

- What is this type of tumor called?

- What is the term that describes the formation of these focal areas?


- Triton tumor (type of MPNST)


- divergent differentiation


You have a patient who presents with cafe au lait spots, multiple cutaneous/diffuse neurofibroas, and has a lot of plexiform neurofibromas.

- What type of neurofibromatosis does this man have?

- What should you be worried about?

- type I


- transformation of plexiform neurofibromas into MPNSTs


-This MRI shows what?

- What disease is this?

- What is the genetic inheritance pattern of this disease?

- MRI shows b/l 8th nerve schwannomas


- Neurofibromatosis type 2


- autosomal dominant

* can also include multiple meningiomas