What is Right Middle Lobe Syndrome?
Middle lobe syndrome (MLS) is a health condition that is often overlooked in medical check-ups, though it’s been known since 1948 when it was first observed in 12 patients. These patients had a medical issue called “nontuberculous middle lobe atelectasis”, which means the middle part of their lungs collapsed due to the pressure of enlarged lymph nodes.
In most instances, there’s a recurring or permanent cloudy appearance in the right middle part of the lung, which is almost always a sign of MLS. The part of the lung known as the “lingula” is also commonly affected since it shares similar physical and functional structures.
While there’s no concrete definition of MLS, it’s generally understood to include two main types associated with recurrent middle lobe atelectasis. These are categorized as obstructive and nonobstructive, meaning the syndrome can either be caused by a blockage or without any blockage in the lung.
What Causes Right Middle Lobe Syndrome?
Middle lobe syndrome is a condition that can often result from something blocking or pressing on the right middle bronchus, which is a passage leading to the lungs. There are two types of middle lobe syndrome: obstructive and nonobstructive.
Obstructive middle lobe syndrome can be caused in two ways: either something is directly blocking the bronchus (intraluminal obstruction), or something outside the bronchus is pressing on it (extraluminal obstruction).
Often, the block is caused by various kinds of tumors like hamartomas, lung cancers, or growths that have spread from other parts of the body. Other common causes of obstructive middle lobe syndrome are swelling around the bronchus due to granulomatous diseases (diseases that cause inflammation), fungal infections that are common in certain areas, and certain types of bacteria. Rarely, other things like aspirating (inhaling) something, mucus plugs, or stones in the bronchus can also create a blockage.
On the other hand, nonobstructive middle lobe syndrome is when there is no detectable blockage identified after examination. Doctors don’t completely understand why this type of middle lobe syndrome happens. It’s thought that it might be due to ineffective ventilation in the middle lobe which is considered an easily blocked area compared to the upper lobes. Nonobstructive middle lobe syndrome can often result from temporary hypoventilation (insufficient ventilation) in chronic inflammatory conditions (like cystic fibrosis) and infections or other conditions that raise the risk for bronchiectasis (a condition where your airways widen and become damaged over time).
Risk Factors and Frequency for Right Middle Lobe Syndrome
There’s not much information available about middle lobe syndrome. What little is known reveals that it’s more common in females than in males, and women tend to show symptoms later in life compared to men. The most common cause of middle lobe syndrome, according to what we understand, is something called a non-obstructive variant. This is a type of long-term inflammation, and it accounts for more than 60% of known cases.
Signs and Symptoms of Right Middle Lobe Syndrome
Patients with a condition called Middle Lobe Syndrome typically show specific symptoms. These symptoms can vary, but they usually include a chronic cough, coughing up blood, trouble breathing, and signs consistent with recurring pneumonia. The key point in their medical history is a persistent, recurring pneumonia that’s hard to treat. During a physical exam, doctors may note wheezing, unusual rattling sounds in the lungs, decreased breath sounds, quick breathing, and in some cases, heavy sweating during bouts of pneumonia. In rare cases, depending on the underlying cause of Middle Lobe Syndrome, patients may fail to gain weight and grow properly or lose weight excessively.
- Chronic cough
- Coughing up blood
- Trouble breathing
- Signs of recurring pneumonia
- Wheezing
- Unusual rattling sounds in the lungs
- Decreased breath sounds
- Quick breathing
- Heavy sweating during bouts of pneumonia (in some cases)
- Failure to gain weight and grow properly or loss of weight (in rare cases)
Testing for Right Middle Lobe Syndrome
The process of diagnosing middle lobe syndrome involves various tests and imaging strategies. However, there’s no single test that stands out as the most reliable for diagnosis. The early stage of evaluation may involve a chest X-ray done from the front and the side of your body, but there’s a catch. These simple X-ray scans might not spot any issues in patients with occasional blockages or recurring pneumonia.
The silhouette sign is a common finding in X-ray images that might suggest middle lobe syndrome. This sign shows your right heart border being blurred by an influx in your right middle lung lobe. This can be seen in front to back or back to front X-ray views.
Despite these signs, an X-ray alone might not be enough to diagnose. Nowadays, doctors rely more on identifying the root cause of the health issue. The use of a bronchoscopy, which is a procedure that allows your doctor to look at your airways, a complete blood count, or advanced chest scan called a CT scan, may provide further insight into the underlying disease responsible for middle lobe syndrome.
Treatment Options for Right Middle Lobe Syndrome
Treatment options for middle lobe syndrome, which can either block or not block your lungs’ airways, are centered around identifying and managing the root cause of the syndrome. Key elements of this treatment often include medications designed to enhance lung function. These may include drugs to break down mucus, chest physiotherapy, inhalers to expand airways, or antibiotics. These drugs and therapies can be beneficial across all forms of middle lobe syndrome, regardless of the underlying cause.
Antibiotics that target a type of bacteria called Pseudomonas are strongly recommended. This is because the structural changes that occur in the lungs due to middle lobe syndrome make it possible for Pseudomonas infections to take hold.
In cases where middle lobe syndrome is causing a blockage, doctors may use a procedure called bronchoscopy to remove any foreign objects or assess any lung tumors. Bronchoscopy involves inserting a small flexible or rigid tube with a light and camera into the airways through the nose or mouth. Occasionally, a technique called insufflation, which involves blowing gas, air, or fluid into a cavity or passage, might be used with bronchoscopy to address lung collapse. However, this method isn’t backed by extensive data, and doctors usually only consider it based on the specific needs and condition of the individual patient.
If managing the condition through non-surgical methods or a bronchoscopy doesn’t lead to significant improvements, surgery may be necessary. One study found that a third of patients responded well to non-surgical management, while another third had to undergo surgery. Surgical treatment, which may include the removal of a part of the lung called a lobectomy, has been predominantly utilized for obstructive MLS and there’s currently limited data concerning its use in children.
What else can Right Middle Lobe Syndrome be?
When a doctor is trying to diagnose a lung-related issue, they need to consider all the possible conditions that could be involved. This list may include, but is not limited to:
- Cystic Fibrosis: an inherited disorder that damages the lungs and digestive system.
- Bronchiectasis: a condition where the airways in the lungs become damaged and widened.
- Aspergillosis: a reaction or infection caused by a type of mold called Aspergillus.
- Pulmonary Sequestration: a rare condition where a section of lung tissue is not connected to the rest of the lung.
- Tuberculosis Infection: an infectious disease that mainly affects the lungs.
- Asthma: a condition in which your airways narrow and swell, producing extra mucus.
- Chronic Obstructive Pulmonary Disease (COPD): a type of obstructive lung disease characterized by long-term breathing problems.
- Immunodeficiency: a state in which the immune system’s ability to fight infectious disease and cancer is compromised or entirely absent.
- Ciliary Disorders: conditions caused by problems with the tiny, hair-like structures on cells called cilia, which play a crucial role in lung function.
- Other rare causes.
