Neurology Potpourri — Peripheral Neuropathy - GK Flashcards
The _____ nervous system consists of nerve fibers connecting the rest of the body with the ________ (brain, spinal cord).
Peripheral
CNS
These connect the head, face, eyes, nose, muscles and ears to brain
Cranial nerves
These connect the spinal cord to the rest of the body
Spinal nerves
What four types of nerves does the peripheral nervous system include?
- Cranial nerves
- Spinal nerves
- Nerves of extremities
- Cervical, brachial and lumbosacral plexuses
___________, ____________ & ________ are the 3 elements of the peripheral nerves.
sensory, motor, autonomic
Peripheral neuropathy results from damage to ____________
any part of the nerve
What parts of the nerve can be damaged that would cause peripheral neuropathy?
- axon
- body of nerve cell
- myelin sheath
- neuromuscular junction
A peripheral neuropathy that affects one nerve
Mononeuropathy
A peripheral neuropathy that affects several discrete nerves
multiple mononeuropathy
OR
mononeuritis multiplex
Peripheral neuropathy that affects a plexus
plexopathy
Peripheral neuropathy that affects a nerve root
radiculopathy
Peripheral neuropathy is characterized by what?
- motor weakness
- sensory loss
AND/OR
- positive sensory symptoms (tingling, burning)
- may also have autonomic symptoms
T/F: Peripheral neuropathy is has a gradual onset and slowly progressive course.
TRUE
T/F: Autonomic symptoms of peripheral neuropathy happen in pts with DM & amyloidosis
TRUE
T/F: Peripheral neuropathy is usually bilateral & symmetric
True
T/F: Peripheral neuropathy is characterized by distal involvement
True
T/F: Etiologies of peripheral neuropathy include hereditary and acquired
True
What are the hereditary causes of peripheral neuropathy?
- Charcot-Marie-Tooth dz (MC)
- Porphyria (rare)
What are inflammatory acquired causes of peripheral neuropathy?
- Guillain Barre Syndrome
- chronic inflamatory demyelinating polyneuropathy
What are infectious acquired causes of peripheral neuropathy?
- Lyme disease
- HIV
- herpes
- VZV
- CMV
- EBV
- hepatitis viruses
- chagas dz
- diphtheria
- leprosy
- rabies
T/F: Acquired etiologies of peripheral neuropathy include rheumatic reasons + organ failure.
TRUE
What are other acquired causes of peripheral neuropathy?
- endocrine
- GI
- malignancy
Vitamin deficiency/excess of which vitamins can cause peripheral neuropathy?
- B12
- B1 (thiamine)
- Vitamin B6 (pyroxidine)
- Vitamin E
- Niacin
- Copper
“Mercedes [BBB]ENC”
What meds cause peripheral neuropathy?
- Abx
- antiretrovirals
- chemo agents
- phenytoin
- thalidomide
What toxins cause peripheral neuropathy?
- Heavy metals
- industrial or environmental substances
Important things to ask when taking History
- fam history for inherited disorders
T/F: You must complete a full neuro exam
True
What labs should you run if a pt comes in with complaints of peripheral neuropathy?
- CBC
- CMP
- A1C (DM mc cause)
- TSH
- B12
- folate
- ESR
- Rf
- ANA
- SPEP
- immunoelectrophoresis or immunofixation
- urine for Bence Jones Protein
**You don’t have to order them all**
What is the purpose of a nerve conduction study w/electromyography?
differentiates between nerve and muscle disorders
differentiates between axonal and demyelinating conditions
When would you order imaging?
What kind of imaging would you order?
If concern for radiculopathy
MRI/CT cervical, thoracic +/- lumbar
What 7 key questions would you ask and what is the main thing you are listening for when asking these questions?
- What systems are involved? (motor, sensory, autonomic, combination?)
- What is the distribution of weakness? (distal vs. proximal, focal/asymmetric vs symmetric)
- What is the nature of the sensory involvement? (temp loss, burning, stabbing pain (small fiber) vibratory or propiocdeptive loss (large fiber)
- What is the temporal evolution? (acute = days-4wks, subacute 4-8wks, chronic >8wks, monophasic, progressive, relapse-remitting)
- Is there evidence of upper motor neuron involvement? (w/o sensory loss or w/sensory loss)
- Is there evidence for a hereditary neuropathy? (fam hx, lack of sensor symptoms despite sensory signs)
- Are there are associated medical conditions? (cancer, DM, conn. tissue dz, autoimmune dz. infection)
T/F: Charcot Marie Tooth dz is the most common hereditary PN
TRUE
Charcot-Marie-Tooth dz is a ______ disorder that starts ________ in life and is a __________ loss of motor and sensory function of ______ & ________ extremeties
demyelination
early
progressive
upper & lower
What are clinical presentations of CMT?
- Distal leg weakness (footdrop)
- foot deformities (pes cavus (hyper arch), hammer toes)
- muscle atrophy below the knee
- reduced/absent DTRs
- sensory deficits

What is the tx for CMT dz?
PT/OT
bracing (ankle-foot orthotics)
What is poyphyria?
A metabolic disorder caused by enzyme deficiency in the heme biosynthetic pathway.
What are the 3 types of porphyria associated with peripheral neuropathy?
- Acute intermittent porphyria
- hereditary coproporphyria
- variegate porphyria
What is the inheritance of porphyria?
autosomal dominant inheritance
Porphyria attacks are precipitated by what 3 things?
- medications
- hormonal changes
- dietary restrictions
Porphyria presentation
sharp abdominal pain followed by agitation, hallucinations, or seizures.
Days later, extremity pain followed by weakness
Weakness in arms or legs (can affect face & bulbar musculature)
Asymmetric, proximal or distal
What is the MC PN in developed countries?
Acquired: Endocrine— DM (diabetic neuropathy)
What types of polyneuropathy happen in diabetic NP?
_- MC*_ distal symmetric sensory or sensorimotor polyneuropathy (DSPN)
- Autonomic neuropathy
- Diabetic neuropathic cachexia
- Polyradiculoneuropathy
- Cranial Neuropathy
- Other mononeuropathies
“PDACCO”
What does autonomic neuropathy consist of?
- abnormal sweating
- dysfunctional thermoregulation
- dry eyes/mouth
- pupillary abnormalities
- cardiac arrhythmias
- postural hypotension
- GI abnormalities (gastroparesis, postprandial bloating, chronic diarrhea, constipation)
- GU dysfunction (impotence, retrogade ejaculation, incontinence)
Risk factors of Diabetic PN?
- long-standing, poorly controlled DM
- retinopathy
- nephropathy
What is the main presentation of Diabetic PN?
Sensory loss:
+/- symptoms
starts in toes, progresses over time up legs and into fingers and arms: “stock-glove”
painless injuries
NOT distributed along a dermatome/myotome
Describe the motor symptoms associated with Diabetic PN?
distal, proximal or focal weakness
Describe the autonomic symptoms of Diabetic PN
Involves CV, GI, GU systems & sweat glands
- ataxia (gait disturbance)
- gait instability
- syncope/near syncope
“AGS”
What is charcot foot & what is it associated with?
Recurring mild fxs that cause this deformity
associated with Diabetic PN

What 4 things do you do for the PE of Diabetic NP?
vibratory sense
monofilament
DTRs
Strength testing
How to diagnose Diabetic PN?
H&P
labs, imaging as needed
Treatment of Diabetic NP
- glucose control: tx DM, prevent progressino
- foot care education
- consider podiatry referral
- medications for pain
- Medications for autonomic dysfunction
What meds would you rx for pain for Diabetic PN pts?
anto-epileptics
anti-depressants
Na channel blockers
Other analgesics
___________ is more commonly associated with proximal neuropathy than neuropathy
Hypothyroidism
Most common neuropathic manifestation of hypothyroidism is ____________
carpal tunnel syndrome
What is the treatment for hypothyroidism PN?
treat the hypothryoidism
What are examples of acquired GI PN ?
celiac dz that does not respond to gluten-free diet
IBD
Is it possible to get PN with the following Rheumatic dzs?
Granulomatosis with polyangiitis (Wegener granulomatosis)
eosinophilic granulomatosis with polyangiitis (Churg-Strauss)
immunoglobulin A vasculitis
IBD
RA
Juvenile idiopathic arthritis
Sjogren syndrome
SLE
scleroderma
mixed connective tissue dz
sarcoidosis
polyarteritis nodosa
Yes, is someone has a rheumatologic or autoimmune condition, they can get PN
T/F: There is often no vasculitic component to the underlying etiology of rheumatic PN
FALSE; there is often a vasculitic component
How does malignancy lead to PN?
- from cancerous invasion or compression of nerves
- paraneoplastic effect
- effect of tx
- from immune compromise
- lymphoma
- multiple myeloma
____% of pts with renal failure develop polyneuropathy
60
Chronic liver failure is associated with what type of PN?
generalized sensorimotor neuropathy: numbness, tingling, minor weakness in distal aspects of primarily lower limbs.
What does this describe?
complication of sepsis and multiple organ failure
often presents as inability to wean patient from ventilator
critical illness polyneuropathy
What type of PN is this describing?
spirochete infection, Borrelia burgdorferi
Transmitted by deer tick, Ixodes dammini
neurologic complications occur in 2nd & 3rd stages of infection and include facial neuropathy, polyradiculoneuropathy or multiple mononeuropathies
Lyme Disease
What is the most commonly seen PN of lyme dz?
Bell’s Palsy
The following are causes of…
pernicious anemia
dietary deficiency/avoidance
gastrectomy
gastric bypass surgery
IBD
pancreatic insufficiency
bacterial overgrowth
medication related (H2 blockers, PPIs, metformin)
Vit B12 (Cobalamin) deficiency
Clinical Presentation of Vitamin B12 (cobalamin) deficiency PN
Glossitis (tongue soreness that looks bright red & smooth)
Paresthesias that starts with hand numbness
sensory loss affecting proprioception and vibration
unsteady gait due to sensory ataxia
diffuse hyperreflexia, absent achilles reflexes
Behavioral changes: mild irritability, forgetfulness, severe dementia and frank psychosis
Diagnostics of B-12 deficiency PN
- Low B-12 level
- anemia and macrocytosis may be absent
- elevated methylmalonic acid
- elevated homocysteine
antibodies to intrinsic factor
antiparietal cell antibodies
Treatment of B-12 deficiency PN
- dietary changes if MILD
- Vit B12 supplementation
- 1000 microgram IM weekly x 1 month, then monthly
- 1000 microgram PO daily
Prognosis of B-12 deficiency PN?
complete reversal of symptoms not always attained
Beriberi dz (dry beriberi references neuropathic symptoms) associated with what?
Thiamine (vit B1) deficiency
Etiologies of B1 deficiency (BeriBeri dz)
MC: chronic alcohol abuse
recurrent vomiting
total parentaral nutrition (tube feedings)
bariatric surgery
restrictive diets
Clinical presentation of BeriBeri (B1 def)
mild sensory loss and/or burning dysesthesias in toes and feet
aching and cramping in lower legs
later: generalized polyneuropathy with distal sensory loss in feet & hands
Treatment of Thiamine (vit B1) deficiency
parenteral thiamine replacement until proper nutrition restored