20 - Peripheral Neuropathy Flashcards
1
Q
Define neuropathy
A
Neurologic pathology entailing the peripheral nervous system, either sensory and/or motor. Occurring at any point from the anterior and/or posterior root ganglion
2
Q
What are the three general forms of neuropathy?
A
- Segmental demyelination
- Axonal degeneration
- Wallerian degeneration
3
Q
What is segmental demyelination?
A
- The selective loss of individual myelin internodes with preservation of the axon.
- After demyelination, the remaining Schwann cells can proliferate and remyelinate.The axons.
- However the reconstituted myelin sheaths are both thinner with a shorter internodal length
4
Q
What is Wallerian degeneration?
A
- Occurs after transection of the axon.
- Proximally the axon will degenerate back to the node of Ranvier, with possible chromatolysis of the cell body
- Distally the axon and its myelin sheath disintegrate and are digested by the Schwann cell.
5
Q
What is axonal degeneration?
A
- Occurs when dysfunction of the neuron renders it unable to maintain its axon.
- The degeneration begins at the peripheral terminal of the axon, and proceeds toward the cell body, there is often chromatolysis of the cell body.
- If the dysfunction can be halted regeneration and recovery of nerve function can occur.
6
Q
What are the classifications of neuropathies?
A
Main etiologies
- DIABETIC
- ALCOHOLIC
- NUTRITIONAL
- GUILLAIN-BARRE
A lot of times alcoholic and nutritional can be in the same category
7
Q
What are some other classificaitons that exist?
A
Others…
- TOXIC
- HEREDITARY
- RECURRENT
- AMYLOIDOSIS
- PORPHYRIA
- INFECTIOUS
- SYSTEMIC
- TUMOR
8
Q
Describe the different types of symptoms you will see in a patient with neuropathy
A
- Motor paralysis
- Tendon reflexes
- Fasciculations and cramps
- Sensory loss
- Paresthesias and dysesthesias
- Sensory ataxia and tremor
- Deformity and trophic changes
- Autonomic disorders
9
Q
Describe motor paralysis
A
Persistent impairment of motor function over weeks, or months signifies segmental demyelination, axonal interruption, or destruction of motor neurons
A feature of most polyneuropathies is the distribution (muscles of the feet and legs affected first and most severely.)
*** REMEMBER: Feet and legs mostly **
This is because the nerves are longest going to the legs
10
Q
Describe tendon reflexes
A
Loss of reflexes is an invariable sign of peripheral nerve disease and can be diminished out of proportion to weakness
11
Q
Describe fasciculations and cramps
A
Neuromyotonia: a state in which the affected muscles ripple and quiver and occasionally cramp.
Use of the muscles increases this activity and there is a reduction in efficiency. Which the patient experiences as stiffness and heaviness
12
Q
What types of sensory loss will we see?
A
Tends to affect the distal segments of the limbs, preferably in the legs
Pattern 1 and Pattern 2
13
Q
Describe pattern 1 of sensory loss
A
Pattern 1: loss of touch pressure, vibratory, two point-discrimination, and joint position sense as the disease worsens (larger fibers effected more) then the disease progresses proximally and includes loss of pain and temp sensation
14
Q
Describe pattern 2 of sensory loss
A
Pattern 2: primary loss of pain and temp with a lesser impairment of pressure, vibratory, and position sense (smaller fibers effected more)
15
Q
Describe paresthesia and dysesthesias
A
PARESTHESIA
- Tend to be very prominent in the hands and feet. (Tingling, electric, novacaine like sensations are the most common paresthesias) which is very hard to treat
- Other paresthesias are extremely painful. ( Have the quality of aching, sharp-cutting, or crushing) which is easier to treat
DYSESTHESIAS
- Perversion of sensation is usually characterized by tingling, or burning pain induced by tactile stimuli. (Stimuli will also radiate and persist after the stimulus is withdrawn.)
16
Q
Describe sensory ataxia and tremor
A
- Proprioceptive deafferentation with retention of a reasonable degree of motor function is the basis of ataxia of gait and limb movement.
- Tremor of fast-frequency, action type may also appear during certain phases of polyneuropathy
These patients may need assistive devices so they don’t fall and break their hip, etc.
17
Q
Describe deformity and trophic changes
A
Tend to be more chronic in nature
- In a number of chronic polyneuropathies the feet, hands, and spine become deformed
- This occurs when the disease begins during childhood
- Foot deformity-30%
- Spine curvatue-20%
18
Q
Describe the autonomic disorders
A
- The two most frequent manifestations are anhydrosis and orthostatic hypertension which occur in small fiber polyneuropathies.
- Other manifestations include un-reactive pupils, lack of tears and saliva, impotence, weak bladder and bowel sphincters.
19
Q
Describe how you go about diagnosing peripheral neuropathy
A
- Once it has been established that a disease of the peripheral nerves is present, the nature of its existence is then determined.
- A neuropathic syndrome is determined by its mode of evolution, and its clinical presentation.
20
Q
Describe the classification of peripheral neuropathies
A
- Axonal peripheral neuropathy
- Demyelinating polyneuropathy
- Hereditary neuropathies
- Neuropathies with inflammation
- Diabetic neuropathies
- Autonomic neuropathy
- Plexopathy
- Mononeuropathy multiplex
21
Q
Describe acute axonal polyneuropathy
A
- ** Associated with alcoholism ***
- Evolves over several days
- Porphyric neuropathy and massive intoxication
- 1-3 days renal and liver failure
- 14-21 days polyneuropathy, progresses for 2-3 weeks then a plateau is reached
- Recovery requires months
Not going to see muscle cramps or quivering, no pain, it is PURELY sensory ***
It will resolve - ACUTE course
22
Q
Describe subacute axonal poly neuropathy
A
- Evolves in weeks
- Usually toxic or metabolic
- Tend to be chronic in evolution
- Management involves removing the offending agent or treating the systemic disorder
- Sensory vs. motor deficit dependent upon toxic agent
May be seen in Parkinsons patient’s supplemented with cobalamin/ B6
23
Q
Chronic axonal polyneuropathy
A
Progression from 6 months to 60 years
- Absence of positive symptoms mostly a motor deficit, and absence of systemic disorder—genetically determined neuropathy
- Relapsing-remitting motor and sensory deficit
Charact. Similar to CIDP
Autosomal dominant
** Viral agent is typically the cause **
A very non specific disorder
24
Q
Describe acute demyelinating polyneuropathy
A
This is DEMYELINATING, not axonal
- Synonymous with Guillain- Barré syndrome
- A virus usually precedes the neuropathy, in the majority of cases****
- Charact: areflexic motor paralysis with a mild sensory disturbance, prognosis is good
- Acute rise of total protein in csp in 1st. week*****
Because there is just an acute rise in CSF proteins, it usually is not even detected because we don’t do that test soon enough
25
Describe subacute demyelinating polyneuropathy
- Acquired neuropathies
- Tend to be a relapsing and remitting neuropathy
- Clinical features similar to GBS. ( But differs in tempo, course, and absence of discernable events)
- May be induced by diphtheria toxin****
Takes several weeks to develop
26
Describe chronic demyelinating polyneuropathy
- Encompass a wide variety of disorders
- Present diagnostically as a mixed axonal-demyelinative finding
- Motor and sensory manifestations
- Difficult to determine the primary event (axonal degeneration or demyelination)
27
Note...
You are NOT going to be tested on those specific classifications because they are so hard to define
28
What are the hereditary components that can lead to peripheral neuropathy
- Charcot Marie tooth
| - Roussy-Levy
29
Describe Charcot Marie tooth
- Characterized by demyelinating and remyelination (motor and sensory deficits)
- Stork leg appearance
- Thenar and hypothenar wasting
- Pes cavus*** and hammertoes
30
Describe Ross-Levy
```
- A variant of Freidrich 's ataxia
& CMT
- Static tremor
- Mild distal weakness
- Sensory loss
- Pes cavus, claw foot***
```
Claw foot is the biggest thing here ***
31
Describe Guillian- Barre syndrome
- Acute ascending motor paralysis
- Possibly triggered by an unknown viral antigen.
- Weakness is the most common symptom, but leg pain, tingling and numbness are initial complaints.
- Reflexes become absent
- Respiratory failure will ensue.
- Aut.- Instability of heart rate and blood pressure
- Lab studies: CSF-( protein is increased without pleocytosis)
The biggest thing here is that they will have a respiratory component ****
32
How do you treat Guillian-Barre syndrome?
- Plasmapharesis
| - Immunoglobulin
33
Describe neuropathies with inflammation
- Acute and chronic forms
- Immune system attacks the nerves
- Typical neuropathy symptoms
- Muscle weakness
- Progressive disorder ****
- Similar to GBS, except chronic
34
How do you diagnose neuropathy with inflammation?
Diagnosis rest on clinical and pathologic pattern:
- Electro-physio pattern
- Elevated CSF protein
- Low-grade inflamm.
- Demyelination-remyelination, immune-mediated
35
Describe treatment of immune mediated neuropathy
Involves a mix of glucocorticoid, immuno-suppressants, and plasmapheresis for management if ambulation threatened
36
Describe neuropathies with disproteinemia
- There is an assoc. Between polyneuropathy and multiple myeloma and macroglobulinemia.
- Sensorimotor
- May be severe and does not reverse with suppression of myeloma
- Consistent with axonal degeneration *****
37
Describe alcohol neuropathy
- A nutritional deficiency often occurs simultaneously with alcohol toxicity.
- The neuropathy is usually sensorimotor caused by axonal degeneration (pain and paresthesias)
- Optic atrophy and myopathy can also be seen in chronic alcoholics
38
Describe drug-induced neuropathy
- Almost all medications can produce toxic neurologic effects if given in high doses or patients with impaired metabolic or excretory dysfunction (renal, or hepatic)
- These neuropathies tend to follow a subacute course.
It is reversible, but you need to weigh the pros and cons - they may NEED the medication so you need to manage the neuropathy
39
Describe diabetic neuropathy
- Occur after long standing hyperglycemia***
| - Approximately 2/3 of all diabetics show evidence of peripheral neuropathy
40
Describe the pathogenesis of diabetic neuropathy
NOT WELL UNDERSTOOD:
- Vascular
- Metabolic
- Immunologic
Just know there are MULTIPLE aspects that contribute to developing diabetic neuropathy
41
What are the different classifications of diabetic neuropathies
Symmetric
1. Distal, primarily sensory polyneuropathy
A. Mainly large fibers
B. Mixed
C. Mainly small fibers
2. Autonomic neuropathy
3. Chronically evolving proximal motor neuropathy
Asymmetric
1. Acute/subacute proximal motor neuropathy
2. Cranial mononeuropathy
3. Truncal neuropathy
4. Entrapment neuropathy in limbs
Just know we are typically looking at distal neuroapthy
Not realy going to go into all of these subtypes
42
Describe distal symmetric polyneuropathy
****
- Most commonly recognized form of diabetic neuropathy****
- Sensory deficits and symptoms, which generally predominate over motor involvement.
- Appears first in the most distal portions of the extremities and progresses proximally (stocking-glove distribution)*****
43
Describe what happens in distal symmetric polyneuropathy
***
- Advance cases result in sensory loss of the chest (as truncal nerves become involved)
- ***Loss of large sensory and motor fibers: diminished light touch and proprioception, the latter resulting in ataxic gait and unsteadiness, as well as loss of muscle function of the feet , and then the hands.
- ***Loss of small fibers: diminished pain and temperature perception
This is why we do monofilatment testing - patient could step on glass and not even know it or they could get into a very hot bath and sustain first degree burns
44
What are neuropathic paresthesias?
- Neuropathic paresthesias (spontaneous uncomfortable sensations), or dysesthesias (contact paresthesias) may accompany both large or small fiber involvement.
- Patients may also complain of contact hypersensitivity to light touch, unbearable superficial burning or stabbing pain, or severe deep bone aching pain.
45
Describe the disease progression in some patients
There are many patient that are free from major symptomatology, and experience subtle changes in numbness, cold, or dead feet.
46
Describe autonmic neuropathy
Autonomic neuropathy is often found in association with somatic polyneuropathy.
47
What are the symptoms of autonomic neuropathy
Symptoms include: atrophic skin, loss of nails, sweating abnormalities, besides other major findings.
Loss of sudomotor function may precipitate cracking of skin and fissure formation, which may become secondarily infected.
48
Describe the STRUCTURAL changes in advanced neuropathy
***
Structural changes result from ligamentous laxity and muscle weakness:
- Prominence of metatarsal heads
- Crowding of toes
- Subluxation of the tarsal and metatarsal heads
49
What are the LATE complications in neuroapthy?
* ** Due to undetected asymptomatic neuropathy may appear:
- Foot ulcerations
- Embedded foreign bodies
- Unrecognized trauma
- Neuroarthropathy
- Chronic venous stasis ulcers
- Vascular ulcers
50
How do you evaluate peripheral neuropathies?
- History and physical
- Chemistry studies
- Urine studies
- EMG
- Nerve conduction
- Nerve/muscle biopsy
Dr. Frush will go into this more later today
For the most part, it will be based on H&P and chemistry studies - Since it is so prevalent, you can diagnose it just by a good evaluation
Etiology is not always going to be known
51
Describe the management of diabetic neuropathy
- Treatment for diabetic neuropathy is symptomatic:
- Palliative, and supportive , with primary emphasis on prophylactic measures to prevent late complications.
- Early diagnosis is essential for prophylaxis. (Reinforcement of good foot care
Your patients will a lot of times tell you that their symptoms get worse when their blood sugars are out of control
52
What are the treatment options of painful neuropathy?
MANY OPTIONS!
- Phenytoin
- Gabapentin
- Carbamazepine
- Tricyclic anti-depressants
- Serotonin re-uptake inhibitor
- NSAIDs
- Topical capsaicin
- Compounded medications
- New Meds: Cymbalta & Lyrica
- Physical therapy
- Splints and braces
53
Describe the management of painful diabetic neuropathy
PRINT THE CHART ON SLIDE 53
He said... "You should be familiar with this"
54
Describe the use of tricyclic antidepressants to treat peripheral neuropathy
Most useful for patinets who have painful neuropathy, mostly at night
- Amitriptyline, nortriptyline, imipramine
- Inhibition of norepinephrine & serotonin reuptake and antagonism of muscarinic cholinergic, histamine H1, and alpha adrenergic receptors.
55
Describe the use of anticonvulsants used to treat peripheral neuropathy
Gabapentin (neurontin)
Lyrica (pregabalin)
You need to start at a very low dose because the side effects are bad - there is a lot of room to experiment because you can give very high doses, so you just need to figure out what works for your patients
56
Describe topical medications that can be used to treat peripheral neuropathy
Capsaicin
- Known to deplete substance P from the terminals and central connections of C-fibers.
- Only good for superficial pain.
Toes can become numb, but it will get rid of the pain
57
Describe local anesthetics that can be used to treat peripheral neuropathy
Mexiletine
- Relatively safe, originally developed as anticonvulsant.
- Its common use is as an antiarrhythmic (similar to Lidocaine)
- Blocks Na+ channel (unable to depolarize, thus decreasing pain detection)
58
Describe muscle relaxants that can be used to treat peripheral neuropathy
Baclofen and metaxalone
| - Analgesic treatment when associated with muscle cramping.
59
Describe alpha-linolenic acid used to treat peripheral neuropathy
Bypasses the impaired step in metabolism
60
Describe aldose reductases inhibitors that can be used to treat peripheral neuropathy
Sorbinil
- Reverses the damage caused by states of hyperglycemia
- May cause hypersensitivity, but the long term effects are positive
*** Experimental ***
61
Describe the hemorheologic agents used to treat peripheral neuropathy
Trental (Pentoxifylline) a Tri-substituted xanthine derivative.
- Alters the viscosity and blood flow.
Pletal (Cilostazol)
- Alters viscosity by inhibiting platelet aggregation
62
What drug can be used for neuropathic pain or restless leg syndrome?
Cymbalta (duloxetine)
Serotonin-norepinephrine re-uptake inhibitor
This is probably a 2nd or 3rd line drug
63
Describe acupuncture for treatment of neuropathy
- Acupuncture analgesia has its earliest documentation between 500 - 300 B.C. in Ancient Chinese medicine.
- Introduced in Europe in 17th. century
64
Describe the methods of acupuncture application
- Needling
- Electric Stimulation
- Transcutaneous Electric Stimulation
- Acu-pressure
- Lasers
- Moxibustion
- Silver Nitrate
- Flouro-Methane Spray
These things try to stimulate neurotransmitter release
- Stimulation of these centers, releases Neurotransmitters
- Endorphins which promote analgesia circulate in the blood and CSF.
- Enkephalins which block the incoming pain signal.
65
What are the pain theories of acupuncture?
- Specificity theory
- Pattern Theory
- Gate Control Theory
- Endogenous Morphine Theory
66
Describe an acupunture clinical trial
- In a study by Abuaisha et al.
46 /73 Patients
- 63 % were on standard medical treatment
- Unresponsive or had side effects to meds
44 Patients finished the full course of acupuncture
- 34 (77%): Improvement of their (primary or secondary symptoms)
- 7/34 (21%): Experienced complete relief
67
Describe a transcutaneous electric stimulation
- TENS has a neuro-physiological and chemical effect
- Walsh et al. Observed an increase in peripheral nerve conduction latency and mechanical pain threshold when TENS (0.2 ms pulse, 110Hz for 5 min..)
- Electric - Stim. was provided by a portable unit (H-wave machine)
- Generates a Biphasic, exponentially decaying waveform (pulse width 4ms, at 25-35 v)
- 30 min. daily for a period of 4 weeks administered through 4 electrodes.
68
What are the results of transcutaneous electric stimulation?
66% Improvement
17% Asymptomatic
17% treatment Failures
Results were very similar to a study on treatment with pharmacotherapy by Pfeifer
66%, 21%, 13%
69
Describe electrotherapy and amitriptyline for symptomatic relief
- Prescribed amitriptyline 50 mg. At bedtime for 20 weeks
- Individuals w/ considerable pain after 4 weeks entered the electrotherapy phase of the protocol.
Results
- Effectiveness of electrotherapy and amitriptyline for symptomatic relief
- Overall 85% of the patients had beneficial effects.
- 36% became asymptomatic
70
Describe magnetic biostimulation in diabetic peripheral neuropathy
- Pathophysiology: Diabetic neurons display selective reduction of inward rectification of the K+ channel.
- Thus channel closure produces an excess of the charged K+ on the inner side of the nerve membrane leading to depolarization***
- It is Hypothesized that the constant magnetic bio-stimulation selectively induces hyperpolarization or repolarization, which will allow a return to baseline axonal potential.
71
Describe research design and methods
- Baseline must be established as to the severity of the neuropathy.
- Patients will receive a set of 475 gauss magnetic footpads or the sham devices.
72
Describe transdermal drug delivery systems
- Alternative for the treatment of neuropathy using topical medications.
- Historically the topical irritants tend to be very painful or may increase the neuropathic pain.
It is important to let patients know that insurance may not cover this and it may be expensive on their part
