Peripheral Neuropathies. Flashcards
Describe: Paranodal/Segmental Demyelinization
- Axon is spared, myelin covering is attacked.
- Slowed conduction velocity without denervation.
- Mild symptoms include impairment of vibratory sense, loss of reflexed, decreased proprioception or weakness.
Describe: Axonal degeneration
- Intrinsic axonal disease or motor neuron disease
- Distal dying back process
- Normal conduction is maintained in intact neurons, absent in affected axons/nerves.
Describe: Wallerian degeneration
- Damage to a local aspect of the axon, death back to proximal node of ranvier.
- Muscle is no longer innervated
- Growth of axon 1-3mm per day, but may not recover.
- ROM must be maintained during repair via electric stimulation.
What is the distribution of polyneuropathies?
- Symmetrical
- LONGEST NEUROPATHY
- STOCKING GLOVE DISTRIBUTION
What are the four classifications of polyneuropathies?
- Inherited
- Metabolic/Nutritional
- Toxic
- Immune/Inflammatory
Give the examples of inherited polyneuropathy
- Charcot-Marie Tooth
- Friedrichs-Ataxia
Give the examples of metabolic/nutritional polyneuropathy
- Diabetic
- Alcoholism
- Vit. B12 deficiency
Give the examples of toxic polyneuropathy
- Heavy Metals
- Drugs
Give the examples of immune polyneuropathy
- Guillain-Bare
- Chronic Inflammatory Demyelinating Polyneuropathy
What are the symptoms of polyneuropathies?
STOCKING GLOVE DISTRIBUTION
- Weakness or flaccid paralysis
- Sensory loss or paresthesias
- DTRs decreased or gone
- Pain
What is Charcot-Marie-Tooth?
- AKA Peroneal muscle atrophy.
- Only non-rare polyneuropathy.
- Typically effects myelin, but there are different forms
How is Charcot-Marie-Tooth passed on?
-autosomal dominant
What are the sings and symptoms of Charcot-Marie-Tooth
- Distal LE muscle atrophy: startingwith peroneals, foot intrinsics, and anterior tib.
- UE affected later in diseases, hand then forearm
- Rarely goes above thigh or elbow
- Decreased DTR, sometimes sensory loss.
When does CMT occur?
End of 1st decade to second decade
How is CMT diagnosed?
-EMG, NCV, nerve biopsy, genetic test
What is fredriechs ataxia?
- Mixed peripheral neuropathy and CNS degeneration, beginning with dorsal root ganglion, impact sensory fibers
- Develop degenerative changes of lateral column of spinal cord and clarkes nucleus.
- CN involvement and dysarthric speech
What are the signs and symptoms of friedrichs ataxia?
- Initially clumsiness of hands, ataxic gait, and decreased DTRs.
- Later: spasticity, severe ataxia, weakness, hyper-reflexia to areflexia
When is the onset of friedrichs ataxia?
-Early teens
What is the clinical course of friedrichs ataxia?
-Death in 10-20 years, usually due to cardiac and/or pulmonary complications (usually by age 35)
What is the clinical course for CMT?
-Slow progression that may self stabilize for long periods.
What is the most common complication of Diabetes?
-Neuropathy
What is the most common cause of neuropathy?
-Diabetes
What happens to nerves during a diabetic neuropathy?
- Combo of axonal degeneration and demyelinization
- Leads to decreased connection velocity.
What are the specific factors that cause diabetic neuropathy?
- Metabolic abnormalities in neurons
- Small blood vessel damage
- Mechanical injury related to entrapments
- smoking/alcohol use
Describe polyneuropathy in the context of diabetes?
- Most common form of diabetic neuropathy (75%)
- Symptoms may be worse at night
- Commonly: distal to proximal loss of sensation starting at the feet, decreased DTRs, not so much pain
- Sometimes: pain and burning in feet, deep aching in legs, loss of temperature sense and normal DTRs.
Describe multiple mononeuropathy in the context of diabetes?
- Asymmetrical: Femoral nerve usually hit, pain and proximal weakness. Resolves over many months and most recover to walking.
- Autonomic: postural hypotension, impaired thermoregulation, sweating, GI symptoms, vaginal dryness, increased heart rate.
Describe mononeuropathies in the context of diabetes?
- sudden focal neuropathy, usually improves over weeks or months.
- high rate of entrapments.
How is diabetic neuropathy treated?
Meds such as:
- tricyclic antidepressants and other antidepressants
- anticonvulsants
- opioids
- topicals such as capsaicin cream
Possibly acupuncture, biofeedback, TENS, magnetic therapy.
What neuropathy arises from alcoholism and Vit B12 deficiency? Describe it?
- Polyneuropathy
- Mixture of sensory and motor
- Aching in calves and soles of feet
- Distal muscle weakness greater in LE than UE
What is the treatment for alcoholic or Vit B12 neuropathy?
-Improved diet.
What occurs during toxic neuropath?
-Axonal degeneration leading to sensory and motor loss
What is the cause of Guillain Barre?
- 50% occur post viral infection (mono or flu)
- Flu vaccine may cause it
Who gets GB?
Very rare, but may occur in anyone.
What happens in GB?
-Rapid inflammatory response of peripheral nerves causing:
1) Diffuse segmental demyelinization ventrally
OR
2) Axonal degeneration with peripheral demyelinization which slows nerve conduction.
What is the pathology of GB?
-Lymphocytes infiltrate nerve roots and damage schwann cells and myelin, may destroy axons.
How is GB diagnosed?
Lumbar puncture, EMG and NCV showing decreased speed of conduction
What is the clinical course of GB?
- Bilateral weakness and paresthesias
- Progressing flaccid paralysis from the LE to the UE
- May be minor motor involvement or major (respiratory muscles)
- Back pain
- Max weakness in 2-3 weeks
What does recovery look like for GB?
- Symptoms recover in reverse order of symptom onset.
- May be fatal (5%) but 85% regain ambulatory status in 6 months.
How is GB treated?
- Respiration is constantly monitored
- IV Immunoglobulin is the preferred treatment but is expensive
- Plasmapheresis is dangerous but used
- PT is used as recovery has already progressed significantly, overworking muscles for strengthening may damage the nerves
What does chronic inflammatory demyelinating neuropathy look like? How is it treated?
- Severe for of GB
- VERY RARE
- Treated via IV immunoglobulin, chronic plasmapheresis, corticosteroids
What are three causes of multiple mononeuropathies ?
- Diabetes
- Ischemic neuropathy secondary to peripheral vascular disease
- Radiation damage
What may cause mononeuropathies?
- Trauma to a nerve
- Pressure to a nerve
- Radiation
- Infections
- Tumors
What may add pressure to a nerve?
-Edema, positioning, tumors, compartment syndrome, entrapment.
What are the three classes of trauma/pressure?
- Neuropraxia
- Axonotmesis
- Neurotmesis
Describe Neuropraxia
- Nerve contusion leading to compression or slight stretching
- Localized demyelinization WITHOUT DAMAGE TO AXON
- Recovery in
Describe Axonotmesis
- Nerve sheath intact but damage to axon leading to wallerian degeneration in a distal direction
- good prognosis
- Time for recovery is related to distance
Describe neurotmesis:
Complete disruption of nerve fibers and connective tissue due to complete severing leading to wallerian degeneration
-Poor prognosis
-May produce spiral or bulbous tips
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What happens in herpes zoster (shingles)?
- Sensory root ganglion damaged, sometimes ventral damage due to recurrence off chicken pox virus
- Follows unilateral dermatome pattern, sometimes bilateral
What happens in bells pallsy? What causes it?
- Viral infection leading to inflammation of CN 7
- Facial symptoms show up as asymmetries
- 85% recover spontaneously
What is a radiculopathy?
- Disease or compassion of spinal root.
- Leads to segmental demyelinization or axonal atrophy, or both
Why are spinal roots vulnerable to damage?
-Thin covering, less blood supply, and less of a blood brain barrier.
