What causes lpr

Overview

Laryngopharyngeal reflux (LPR) is a condition where stomach acid and other digestive contents travel up the esophagus and reach the larynx (voice box) and pharynx (throat). This reflux can irritate the delicate tissues in these areas, leading to a range of symptoms that often differ from typical gastroesophageal reflux disease (GERD). While GERD is characterized by heartburn and regurgitation, LPR often presents with symptoms like chronic hoarseness, a persistent need to clear the throat, a feeling of a lump in the throat (globus sensation), difficulty swallowing, and sometimes a cough. It's sometimes called 'silent reflux' because the classic heartburn symptom is often absent or mild.

What Causes LPR?

The fundamental cause of LPR is the abnormal reflux of stomach contents into the upper aerodigestive tract. This occurs when the mechanisms that normally prevent reflux fail. The primary culprits involved are:

1. Esophageal Sphincter Dysfunction

The lower esophageal sphincter (LES) is a muscular ring at the bottom of the esophagus that acts like a valve, opening to allow food into the stomach and closing to prevent stomach contents from flowing back up. In LPR, this sphincter may not close properly or may relax inappropriately, allowing stomach acid and pepsin (a digestive enzyme) to escape upwards. Similarly, the upper esophageal sphincter (UES), located at the top of the esophagus, can also play a role. While less understood in LPR, its function is to prevent reflux from entering the pharynx and larynx. Impaired function in either sphincter can contribute to LPR.

2. Stomach Acid and Digestive Enzymes

The stomach produces hydrochloric acid to aid digestion and kill bacteria. It also produces enzymes like pepsin. When these substances reflux into the esophagus and beyond, they can cause damage. While the esophagus has some protective mechanisms against acid, the lining of the pharynx and larynx is much more sensitive. The pepsin enzyme is particularly problematic because it remains active in a neutral pH environment, meaning it can continue to damage tissues even after the acid has been neutralized by saliva. This is a key difference from GERD, where symptoms are often directly related to acid exposure.

3. Pepsin Activity and Tissue Damage

Once pepsin reaches the larynx and pharynx, it can bind to the mucosal cells and remain active. It can then initiate a cascade of inflammatory responses, leading to tissue damage, edema (swelling), and changes in cell structure. This chronic irritation is responsible for many of the characteristic symptoms of LPR, such as hoarseness (due to inflammation of the vocal cords) and the sensation of a lump in the throat (due to irritation and swelling in the pharynx).

4. Weakened Mucosal Defense

The lining of the esophagus, pharynx, and larynx has natural defense mechanisms, including mucus production and bicarbonate secretion, which help neutralize acid and protect the tissues. In individuals with LPR, these defense mechanisms may be compromised, making them more susceptible to damage from refluxate. Factors that can weaken these defenses include dehydration, smoking, and certain medications.

5. Role of Bile

While acid reflux is the primary concern, bile salts from the duodenum (the first part of the small intestine) can also reflux into the stomach and then into the esophagus and beyond. Bile reflux, especially when combined with acid reflux (mixed reflux), can be even more damaging to the esophageal and pharyngeal mucosa due to its irritating properties. This is less common than acid reflux but can be a significant contributing factor for some individuals.

Contributing Factors and Triggers

Several lifestyle and dietary factors can contribute to or exacerbate LPR. These are often similar to those that trigger GERD, but their impact on LPR can be more pronounced due to the increased sensitivity of the upper airway tissues:

• Dietary Triggers: Common culprits include fatty foods, spicy foods, chocolate, caffeine (coffee, tea, soda), alcohol, citrus fruits and juices, tomatoes and tomato-based products, onions, and mint. These can relax the LES or increase stomach acid production.
• Lifestyle Habits: Eating large meals, eating close to bedtime, lying down soon after eating, obesity (increased abdominal pressure), smoking, and chewing gum or sucking on mints (can increase swallowing frequency and saliva production, which may initially help but can lead to more LES relaxation) can all play a role.
• Anatomical Factors: Hiatal hernias, where part of the stomach protrudes through the diaphragm, can impede LES function and contribute to reflux.
• Medications: Certain medications, such as calcium channel blockers, anticholinergics, and some asthma medications, can relax the LES.
• Pregnancy: Hormonal changes and increased abdominal pressure during pregnancy can lead to or worsen reflux symptoms.

LPR vs. GERD

It is crucial to understand the distinction between LPR and GERD. While both involve reflux, the primary difference lies in the location of symptom manifestation and the typical symptom profile. In GERD, the reflux primarily affects the esophagus, leading to heartburn and regurgitation. In LPR, the reflux reaches higher into the pharynx and larynx, causing symptoms in the throat and voice box. Many individuals with LPR do not experience significant heartburn, making diagnosis more challenging. It's possible to have both GERD and LPR, or one without the other. Some researchers believe LPR may be a distinct entity or a variant of reflux disease.

Diagnosis and Management

Diagnosing LPR often involves a combination of symptom assessment, physical examination (including laryngoscopy to visualize the throat and vocal cords for signs of irritation), and sometimes objective tests like a 24-hour pH monitoring study. Management typically focuses on lifestyle modifications, dietary changes, and medications aimed at reducing stomach acid production and promoting healing of the inflamed tissues. Proton pump inhibitors (PPIs) are commonly prescribed, often at higher doses and for longer durations than used for GERD.