16 - Diabetic Neuropathy Flashcards
What percent of diabetic patients have mild to severe forms of nervous system damage?
NEED TO KNOW ***
60-70%
What does diabetic neuropathy include?
- Impaired sensation or pain in the feet or hands
- Slowed digestion of food in the stomach
- Carpal tunnel syndrome
- Other nerve problems
What is the number 1 cause of amputation in the US?
Trauma
What is the number 1 non-traumatic cause of amputation?
Diabetes
More than 60% of nontraumatic lower-limb amputations in the United States occur among people with diabetes.
What are the two CRITICAL risk factors for diabetic neuropathy?
- Poor glucose control *****
- Duration of diabetes over 25 years ***** (ANY patient diagnosed early in life has a higher risk)
Poor glucose control = an A1c over 6.5
What are the other risk factors for diabetic neuropathy?
- Damage to blood vessels
- Mechanical injury to nerves (carpal tunnel syndrome)
- Autoimmune factors (inflammation of the nerves due to autoimmune dysfunction can aggravate neuropathy)
- Genetic susceptibility (inherited traits can increase susceptibility to nerve disease)
- Lifestyle factors
Describe the mechanical injury and autoimmune disease
If a diabetic was compliant and well controlled, but had an injury to the nerve (carpal tunnel), then she will be at increased risk of developing diabetic neuropathy
If you have ANY autoimmune disease on top of diabetes, you have a higher risk of neuropathy
What lifestyle factors contribute to diabetic neuropathy?
- Smoking
- Alcohol abuse
These can cause blood vessel damage leading to nerve damage
Can cause diabetic neuropathy or make the diabetic neuropathy worse
Describe the pathogenesis of diabetic neuropathy
The mechanisms by which diabetic neuropathy develops are still being researched.
Describe the flowchart of pathogenesis hypotheses regarding diabetic neuropathy
- If a patient has uncontrolled diabetes for over 25 years, there will be an increase AGE formation
- There is increased glucose in the serum, but also increased glucose inside of the nerve cells
- This can lead to an increased polyol pathway activity
- Further, glucose in the nerves can increase free radical formation
- Once AGEs in the nerves have formed, there are a lot of functions, including cytokine release and promotion of coagulation
- AGEs can also “quench” NO which is critical for muscle relaxation
- After the NO has been quenched, it will cause vasoconstriction
- The polyl pathway increase and will also decrease the generation of NO
- The overall response is a high level of vasoconstrction
- Endothelin is a hormone that will further contribute to vasoconstriction
- Diabetes will decrease GLA, which is Gamma linolenic acid, which are precursors of PG
- Once there is a decrease of GLA, there will be a lesser production PG and a lesser ability for vasodilation, further contributing to vasoconstriction
- If you have diabetes, we know that it can cause microvascular structure damage, including BM thickening and endothelial swelling
- All of these things contribute together to have nerve hypoxia, which is an irreversible step that lowers nerve conduction velocity and causes structural damage to nerves
What pathological changes will you see in diabetic neuropathy?
KNOW THIS SLIDE
These are the pathological changes in nerves that cause diabetic neuropathy
- Axonal loss
- Focal demyelination & regeneration
There will be a decreased conduction velocity and a decreased sensory threshold
What are the four different classifications of diabetic neuropathy?
- Symmetric polyneuropathy
- Autonomic neuropathy
- Polyradiculopathy
- Mononeuropathy
NEED TO KNOW ALL FOUR
Describe symmetric polyneuropathy
Not emphasized for exam, but clinically relevant
- Most common form of diabetic neuropathy
- Affects distal lower extremities and hands (“stocking-glove” sensory loss)
What are the signs and symptoms of symmetric polyneuropathy?
Symptoms/Signs
- Pain
- Paresthesia/dysesthesia (“something is wrong with my hands and feet – they don’t feel normal”)
- Loss of vibratory sensation
What are the complications of polyneuropathy?
NEED TO KNOW
- Ulcers***
- Charcot arthropathy (joint deterioration)
- Dislocation and stress fractures
- Amputation
Ulcers are a VERY important complication of polyneuropathy***
Even though amputation is very severe, it is less of a common complication, ulcers are the most common***
What are the treatment options for symmetric polyneuropathy?
- Glucose control
- Pain control
- Foot care
How do we control pain in polyneuropathy?
- Tricyclic antidepressants
- Topical creams
- Anticonvulsants
Describe autonomic neuropathy
Affects the autonomic nerves controlling internal organs
- Peripheral
- Genitourinary (GU)
- Gastrointestinal (GI)
- Cardiovascular (CV)
Remember, INTERNAL ORGANS
How do we classify autonomic neuropathy?
Clinical or subclinical based on the presence or absence of symptoms
- Clinical = you feel it
- Subclinical = you can’t feel it
Describe peripheral autonomic dysfunction
Contributes to the following signs and symptoms
- Neuropathic arthropathy (Charcot foot)
- Aching, pulsation, tightness, cramping, dry skin, pruritus, edema, sweating abnormalities
- Weakening of the bones in the foot leading to fractures
The weird things that cannot be explained by anything else can be explained by autonomic dysfunction
How do you treat peripheral autonomic dysfunction?
- Foot care/elevate feet when sitting
- Eliminate aggravating drugs
- Reduce edema
- -> midodrine
- -> diuretics
- Support stockings
- Screen for CVD
What are the signs and symptoms of genitourinary autonomic neuropathy?
- Bladder dysfunction
- Retrograde ejaculation
- Erectile dysfunction
- Dyspareunia (pain during intercourse which occurs frequently in elderly women)
What is the treatment for bladder dysfunction due to genitourinary autonomic neuropathy?
Voluntary urination; catheterization
What is the treatment for retrograde ejaculation due to genitourinary autonomic neuropathy?
Antihistamine
Retrograde ejaculation patients have infertility because the sperm goes right back into the bladder (urine) – either do in vitro fertilization or antihistamines
