What are the causes of autonomic nervous system (ANS) dysfunction?

From the Guidelines

Autonomic dysfunction should be managed based on the specific symptoms and underlying cause, with a focus on lifestyle modifications and targeted pharmacological interventions to improve morbidity, mortality, and quality of life. The management of autonomic dysfunction involves a comprehensive approach, including lifestyle modifications and pharmacological interventions. For orthostatic hypotension, initial management includes increasing fluid intake to 2-3 liters daily, adding salt to the diet (8-10g daily), wearing compression stockings, and performing physical countermaneuvers like leg crossing when standing, as recommended by recent guidelines 1. Medications may include fludrocortisone (starting at 0.1mg daily) to increase blood volume, midodrine (2.5-10mg three times daily) to constrict blood vessels, or droxidopa (100-600mg three times daily) for severe cases, with the choice of medication depending on the severity of symptoms and underlying conditions 1. For gastrointestinal symptoms, metoclopramide (5-10mg before meals) can help with gastroparesis, while loperamide (2-4mg as needed) may control diarrhea, as suggested by studies on diabetic autonomic neuropathy 1. Urinary symptoms might require bethanechol (10-50mg three times daily) for retention or anticholinergics like oxybutynin (5mg twice daily) for urgency, with the goal of improving quality of life and reducing morbidity. Hyperhidrosis (excessive sweating) can be treated with topical antiperspirants containing aluminum chloride, oral anticholinergics like glycopyrrolate (1-2mg twice daily), or botulinum toxin injections, depending on the severity of symptoms and patient preferences. Lifestyle modifications like adequate hydration, regular exercise, and avoiding triggers (heat, alcohol, large meals) are essential components of managing autonomic dysfunction, as emphasized by recent guidelines 1. The treatment should be individualized based on symptom severity, underlying conditions, and potential medication side effects, with a focus on improving morbidity, mortality, and quality of life. Some key points to consider in the management of autonomic dysfunction include:

• Identifying and addressing underlying causes, such as diabetes or other systemic diseases
• Monitoring and managing orthostatic hypotension and other cardiovascular complications
• Implementing lifestyle modifications to improve symptoms and quality of life
• Selecting pharmacological interventions based on symptom severity and underlying conditions
• Regularly assessing and adjusting treatment plans to optimize outcomes and minimize side effects. Overall, the management of autonomic dysfunction requires a comprehensive and individualized approach, with a focus on improving morbidity, mortality, and quality of life, as recommended by recent guidelines and studies 1.

From the Research

Autonomic Dysfunction

• Autonomic dysfunction can lead to various symptoms, including orthostatic intolerance, palpitations, constipation or diarrhea, early satiety, urinary retention or incontinence, and erectile dysfunction 2.
• The condition can result from a decrease in cardiac output or defective or inadequate vasoconstrictor mechanisms, leading to an excessive fall in blood pressure while standing 3.
• Autonomic dysfunction can be caused by a pathologic lesion in sympathetic neurons (neurogenic orthostatic hypotension) or secondary to other medical causes (non-neurogenic orthostatic hypotension) 4.

Treatment Options

• Midodrine, a peripheral alpha-adrenergic agonist, has been shown to be effective in treating orthostatic hypotension due to autonomic failure in patients with significant preservation of autonomic reflexes 5.
• Fludrocortisone, a mineralocorticoid, can increase blood volume and blood pressure, and is considered a first- or second-line pharmacological therapy for orthostatic hypotension 3.
• Other treatment options include volume expansion with fludrocortisone, sympathetic enhancement with midodrine, droxidopa, and norepinephrine reuptake inhibitors, as well as nonpharmacologic measures such as increasing fluid and salt intake and venous compression methods 4.

Management Strategies

• Management of orthostatic hypotension is aimed at improving quality of life and reducing symptoms rather than normalizing blood pressure 4.
• Distinguishing between neurogenic and non-neurogenic orthostatic hypotension, as well as between central and peripheral dysfunction, has therapeutic implications 4.
• Patients with peripheral sympathetic denervation may respond better to norepinephrine agonists/precursors, while those with central autonomic dysfunction may respond better to norepinephrine reuptake inhibitors 4.