System diseases:

• Neurological disorders, such as Stroke, amyotrophic lateral sclerosis (ALS), Multiple sclerosis (MS), Poliomyelitis, Parkinson disease, Myasthenia gravis, etc, which may be firstly noticed as trouble initiating swallow called oropharyngeal dysphagia.
• Scleroderma. It is a connective tissue disease which involves changes in esophagus and several other organs. Scleroderma can weaken the lower esophageal sphincter, causing acid reflux.

Adjacent compression:

• Enlarged heart, lymph notes, aorta dissection, or mass in the media sternum can produce symptom of dysphagia.

Esophageal dysphagia:

• Achalasia. Achalasia is a condition of weakness of the esophageal muscle and the lower esophageal muscle (sphincter) unable to relax causing trouble swallowing. Patients may have regurgitation of undigested food back into the throat. It tends to get worse over time.
• Pseudoachalasia. Cancer of the esophagus or upper stomach and infectious diseases, such as Chagas disease may cause symptoms like those of achalasia.
• Esophageal spasm. Inappropriate esophageal muscle contraction can cause dysphagia and chest pain. This includes nutcracker esophagus and diffuse esophageal spasm.
• Esophageal stricture. Narrowing in your esophagus can make it difficult for food to pass down and even can cause food to be stuck in the esophagus. This may be from scar tissue from injury to your esophagus, such as gastroesophageal reflux disease (GERD), chemicals, etc. It can be also from esophageal rings, such as Schatzki ring (see picture at upper right), or from tumors.
• Esophageal tumors. Both benign and malignant tumors can cause dysphagia. You should alarm yourself and seek medical attention immediately especially if you have one or more of the following conditions: smoker, anemia, weight loss, dark stools, family history of esophageal cancer, etc.
• Gastroesophageal reflux disease (GERD). GERD sometime can be associated with dysphagia since it causes acid reflux, which can lead to spasm or stricture of your esophagus.
• Eosinophilic esophagitis. Eosinophils are allergic cells. If a lot of these cells infiltrate into your esophagus by some triggers such as food allergy, you may have dysphagia. This problem has been recognized more frequently in recent years.
• Chemical injury. Medicines like potassium chloride, nonsteroidal anti-inflammatory drugs (NSAIDs), or antibiotics (such as tetracycline, doxycycline, trimethoprim-sulfamethoxazole, clindamycin) can damage esophageal mucosa and cause dysphagia. Patient may also have symptom of painful swallowing called odynophagia.
• Radiation therapy. Radiation therapy in the neck and chest can cause inflammation and scarring of the esophagus, which may result in dysphagia.
• Esophageal infection. Both viral and fungal (see picture at right lower corner) infections in esophagus can cause dysphagia which may also associated with odynophagia. This mostly happens in diabetic patients, patients on immunosuppressant therapies, or AIDS, etc.
• Pharyngeal or esophageal diverticula. A small pouch forms and collects food particles in your throat or esophagus, can produce dysphagia, bad breath, and food regurgitation.

Diagnosis and Treatment:

Diagnosis usually involves an office visit along with one or more of the following tests:

• Simple blood works
• X-ray
• CT Scan
• Dynamic swallowing study
• Endoscopy (golden standard)
• Manometry

After establishment of the diagnosis, treatment may involve one or more of the following modalities:

• Medication therapy
• Esophageal dilation
• Surgery

References:

1. PubMed Health.
2. Wikipedia.
3. Mayo clinic online health information.
4. Sleisenger and Fordtran's Gastrointestinal and Liver Disease- by Mark Feldman MD, et al.
5. The Little Black Book of Gastroenterology-by David W. Hay.
6. Principles of Clinical Gastroenterology by Tadataka Yamada, et al.