Autonomic neuropathy

Overview 

Autonomic neuropathy results from damage to the nerves that regulate involuntary body functions, such as blood pressure, temperature control, digestion, bladder function, and sexual function. This nerve damage disrupts the communication between the brain and various organs within the autonomic nervous system, including the heart, blood vessels, and sweat glands. 

Diabetes is the leading cause of autonomic neuropathy, though other health conditions, infections, or certain medications can also trigger this disorder. The symptoms and treatments for autonomic neuropathy differ depending on which nerves are affected, making individualized care essential.  

Symptoms  

Signs and symptoms of autonomic neuropathy vary depending on the specific nerves affected. These may include: 

• Dizziness and fainting: This can occur when standing up, due to a sudden drop in blood pressure. 
• Urinary problems: Symptoms may involve difficulty starting urination, loss of bladder control, difficulty sensing a full bladder, and an inability to completely empty the bladder. Incomplete bladder emptying can lead to urinary tract infections. 
• Sexual difficulties:  
  • In men: Issues such as erectile dysfunction or problems with ejaculation. 
  • In women: Symptoms can include vaginal dryness, low libido, and difficulty reaching orgasm. 

• Digestive issues:  
  • Feeling full after eating only a small amount. 
  • Loss of appetite. 
  • Digestive problems such as diarrhea, constipation, abdominal bloating, nausea, vomiting, difficulty swallowing, and heartburn. 

• Hypoglycemia unawareness: The inability to recognize low blood sugar levels due to the absence of warning signs like shakiness. 
• Sweating problems: This includes either excessive sweating or insufficient sweating, which can affect the body’s ability to regulate temperature. 
• Sluggish pupil reaction: Difficulty in adjusting from light to dark, which can impair night vision and make driving at night challenging. 
• Exercise intolerance: The heart rate may not adjust appropriately during physical activity, making exercise difficult. 

If you notice any of the following signs and symptoms, especially if you have poorly controlled diabetes, it’s crucial to seek medical attention promptly: 

• Type 2 diabetes: The American Diabetes Association recommends annual screening for autonomic neuropathy starting at the time of diagnosis. 
• Type 1 diabetes: Annual screening for autonomic neuropathy is advised beginning five years after diagnosis. 

Causes

Autonomic neuropathy can result from various health conditions and may also arise as a side effect of treatments for other diseases, such as cancer. Common causes include: 

• Diabetes: The most frequent cause of autonomic neuropathy, particularly when poorly controlled. Diabetes can gradually damage nerves throughout the body. 
• Amyloidosis: A condition involving abnormal protein buildup in organs, which can impact both the organs and the nervous system. 

• Autoimmune diseases: These occur when the immune system attacks and damages parts of the body, including nerves. Examples include: 
  • Sjogren syndrome 
  • Systemic lupus erythematosus 
  • Rheumatoid arthritis 
  • Celiac disease 
  • Guillain-Barre syndrome, which rapidly affects autonomic nerves. 

• Paraneoplastic syndrome: An immune response triggered by certain cancers that can lead to autonomic neuropathy. 
• Certain medications: Drugs used in cancer treatment, such as chemotherapy, can cause autonomic neuropathy. 
• Infections: Some viruses and bacteria, including HIV, botulism, and Lyme disease, can lead to autonomic neuropathy. 
• Inherited disorders: Certain genetic conditions can also cause autonomic neuropathy. 

Risk factors 

Factors that can increase the risk of autonomic neuropathy include poorly controlled diabetes, which significantly raises the likelihood of nerve damage. Other health conditions, such as amyloidosis, porphyria, and hypothyroidism, also contribute to the risk. Additionally, cancer and its treatments can be associated with the development of autonomic neuropathy.

Diagnosis   

Autonomic neuropathy can develop as a complication of various conditions. The necessary tests depend on specific symptoms and existing risk factors. Here’s an overview of the diagnostic process: 

For Individuals with known risk factors 

In cases where conditions like diabetes or certain treatments increase the risk of autonomic neuropathy, healthcare providers will: 

• Conduct a physical examination to assess overall health. 
• Discuss symptoms to gain a better understanding of the condition. 
• Monitor for neuropathy signs when receiving treatments known to cause nerve damage, such as certain cancer therapies. 

For individuals without known risk factors 

When symptoms of autonomic neuropathy appear without obvious risk factors, diagnosis may involve: 

• Reviewing medical history and symptoms in detail. 
• Performing a physical examination to identify potential signs of neuropathy. 

Healthcare providers may recommend the following tests to evaluate autonomic function: 

• Autonomic function tests: These assess how heart rate and blood pressure respond to exercises like deep breathing and the Valsalva maneuver. 
• Tilt-table test: This test monitors changes in blood pressure and heart rate when moving from lying down to standing up, simulating the body’s response to such movements. 
• Gastrointestinal tests: Typically performed by a gastroenterologist, these tests are used to diagnose digestive issues like gastroparesis. 
• Quantitative Sudomotor Axon Reflex test: This test evaluates how the sweat glands respond to nerve stimulation, involving a small electrical current to measure nerve responses. 
• Thermoregulatory Sweat test: A powder is applied to the skin that changes color as sweating occurs. The test is conducted in a chamber with increasing temperature, and the sweat pattern helps in diagnosing autonomic neuropathy. 
• Urinalysis and bladder function tests: For those experiencing bladder symptoms, a series of tests can evaluate bladder function and detect issues related to neuropathy. 
• Ultrasound: An ultrasound may be used to create images of the urinary tract when bladder issues are present, aiding in diagnosis. 

Treatment 

The treatment for autonomic neuropathy focuses on two main goals:  addressing the underlying cause and managing specific symptoms. 

1. 1. Treating the underlying disease: The primary goal is to manage the disease or condition causing the nerve damage. For example, if diabetes is the underlying cause, tight control of blood sugar levels is essential to prevent further nerve damage. However, it’s important to note that in about half of the cases, no underlying cause for autonomic neuropathy is found. 
2. Managing specific symptoms: Treatment is tailored to the specific symptoms and areas of the body affected by nerve damage.

Gastrointestinal symptoms:  

• Dietary changes: Increase dietary fiber and fluids. Fiber supplements like Metamucil or Citrucel may also help. Gradually increase fiber intake to avoid gas and bloating. 
• Medication to aid stomach emptying: Metoclopramide (Reglan) can help your stomach empty faster by increasing digestive tract contractions. This medication should not be used for more than 12 weeks due to potential side effects like drowsiness. 
• Constipation relief: Over-the-counter laxatives can ease constipation. Consult your healthcare provider for guidance on frequency. 
• Diarrhea relief: Antibiotics can prevent excessive bacterial growth in the intestines, helping to treat diarrhea. Over-the-counter anti-diarrheal medications might also be helpful. 

Urinary symptoms: 

• Bladder retraining: Following a schedule for fluid intake and urination can increase bladder capacity and improve bladder control. 
• Medication for bladder control: Medications can be prescribed to manage an overactive bladder or assist with bladder emptying. 
• Urinary assistance (catheterization): A catheter may be used to help empty the bladder. 

Sexual dysfunction:  

• For men:  
  • Erectile dysfunction medications: Drugs like sildenafil, vardenafil, tadalafil, and avanafil can help achieve and maintain an erection. Use with caution if you have a history of heart disease, stroke, or high blood pressure. Avoid if taking organic nitrates. 
  • External vacuum pump: This device uses a hand pump to draw blood into the penis, with a tension ring maintaining the erection for up to 30 minutes. 

• For women:  
  • Vaginal lubricants: These can reduce dryness and make sexual intercourse more comfortable. 
  • Medications for low sexual desire: Certain medications are approved for premenopausal women experiencing low sexual desire. 

Heart rhythm and blood pressure symptoms:  

• Dietary adjustments: A high-salt, high-fluid diet can help maintain blood pressure in severe cases, though it may not be suitable for those with heart failure due to the risk of high blood pressure or swelling. 
• Compression garments: Waist binders or thigh-high compression stockings can improve blood flow. 
• Medications for blood pressure:  
• To raise blood pressure: Fludrocortisone helps the body retain salt, aiding in blood pressure regulation. Midodrine, droxidopa, octreotide, and pyridostigmine are other options, though they come with potential side effects. 
• To regulate heart rate: Beta blockers may be prescribed if your heart rate becomes too high during physical activity. 

Sweating issues:  

• Excessive sweating: Glycopyrrolate may be prescribed to reduce sweating. Possible side effects include diarrhea, dry mouth, urinary retention, blurred vision, and others. This medication may increase the risk of heat-related illnesses, such as heatstroke, due to reduced sweating.