Dysgeusia

Dysgeusia refers to a distortion in the sense of taste that leaves a persistent foul, metallic taste in the mouth. The taste could even be described as bitter and rancid that stays on and disturbs the desire to eat.

Dysgeusia, if sustained, can have an impact on the quality of life of patients. It can lead to problems like loss of appetite, malnutrition and depression. Dysgeusia can occur at any age. However, taste disturbances are common among the elderly taking multiple medications. Our taste buds are found on the tongue and on the roof of the mouth. They contain cells that collect taste information and send it to the brain. The sense of taste is closely associated with the sense of smell. Some people with Dysgeusia also have an altered sense of smell that affects sense of taste. This is because most of the taste sensations are controlled by nerve cells involved with smell.

Dysgeusia could be caused by several conditions ranging from simple cold and dental problems to serious ones like cancer treatment that alters an individual's sense of taste. Some of the causes are listed below.

• Deficiency of zinc or vitamins in the body
  
• Problem related to the brain or entire nervous system
  
• Chemotherapy treatment
  
• Excessive smoking
  
• Brain tumor
  
• Cold, ear infections and dental related problems like gingivitis, tooth abscess
  
• Certain medications
  
• Copper, lead or mercury poisoning
  
• Gastric reflux
  
• Jaundice

Diagnosis of Dysgeusia

Dysgeusia is most often diagnosed during a clinical examination. The physician will make note of the history of the patient and will also enquire about the present medical condition that may be causing taste distortion. He may order few blood tests to assess zinc and other vitamin deficiencies that might be causing metallic taste. There are certain 'taste tests' to identify the sense of taste and smell. Taste tests allow the patient to respond to different concentrations of a substance. Sometimes a chemical that releases sour, sweet, bitter and salty taste is directly applied on the tongue that helps in determining if Dysgeusia is present or not.

If the Dysgeusia is related to neurological condition that has damaged the nerves of mouth or head, CT scan and other imaging tests are performed to assess the extent of damage.

Treatment of Dysgeusia

Many a times, Dysgeusia is reversible. Treatment for the condition depends upon the underlying disease that is causing the metallic taste. Dysgeusia disappears on its own if it is caused by minor problems like cold and dental infections. However, Dysgeusia may almost become untreatable, if it is caused by nerve damage.

If, certain medication is causing the bitter taste in the mouth, the doctor may alter the dosage or prescribe alternate medicine to provide relief. Recent studies show that artificial saliva and mouth wash containing pilocarpine gives much needed relief in cases of medicine-induced Dysgeusia.

Some simple remedies to improve the saliva flow in the mouth also go a long way in treating taste distortion. Chewing on breath mints, sugarless gum, or lozenges will encourage saliva and remove the bitter taste in the mouth.

Most patients suffer from Dysgeusia due to zinc deficiency. Such patients are treated with zinc supplementation.

Few natural remedies like rinsing the mouth with salt solution, brushing twice or thrice a day, consuming citrus fruits, adding more seasoning and spice to the food, and drinking more water are simple measures that help in treating Dysgeusia.

Paraneoplastic Syndrome

The first report of Paraneoplastic syndrome is attributed to a French physician, M Auche, who described the involvement in a peripheral nervous system in cancer patients in 1890. This syndrome is a group of signs and symptoms caused by a substance that is produced by a tumor, or in reaction to a tumor. Paraneoplastic syndrome is defined as a rare disorder triggered by a response to neoplasm of an immune system that is altered. These are clinical syndromes produced by tumor although they occur remotely from the tumor itself.

The symptoms may be of any nature – endocrine, neuromuscular or musculoskeletal, cardiovascular, cutaneous, hematologic, gastrointestinal, renal or miscellaneous. Fever is the most common sign. Other clinical symptoms may be benign but syndromes could be varied; from a malignant carcinoid syndrome to Cushing syndrome. In cancer patients, the central nervous system involvement can be detected and it is a prominent manifestation of cancer.

Because of their protean manifestations, Paraneoplastic syndromes are managed by a medical team of physicians, including medical oncologists, surgeons, radiation oncologists, endocrinologists, hematologists, neurologists and dermatologists.

Causes

This syndrome can be due to a number of causes, including hormones or biologically active products, made by tumor, which blocks normal hormone, autoimmunity, immune-complex production and immune suppression. But, this is not caused by the primary tumor itself, or by its metastases, or by compression, infection, nutritional deficiency, or treatment of tumor.

Patients with family history of malignancies are at an increased risk and should be screened for cancer. Paraneoplastic syndromes occur typically among middle-aged to older patients. They are mostly diagnosed with cancers of the lung, breast, ovaries, or lymphatic system or lymphoma.

These symptoms sometimes appear before the diagnosis of a malignancy. When the tumor breaks immune tolerance and begins to attack the normal tissue expressing that protein, this syndrome become prominent.

Types of Paraneoplastic Syndrome

Due to the complexity of this syndrome, its clinical presentations may vary greatly. Hence, Paraneoplastic syndromes is divided into four main categories - endocrine, neurological, mucocutaneous, and hematological syndromes as well as a host of others including rheumatologic, renal, gastrointestinal, Cutaneous and miscellaneous.

Fever, dysgeusia, anorexia, and cachexia are included under miscellaneous category. Fever is associated with lymphomas, acute leukemias, sarcoma and carcinomas.

Rheumatologic syndrome includes polyarthritis, particularly in patients with myelomas, lymphomas, acute leukemia, malignant tumors of the colon, pancreas, prostrate. Scleroderma may precede the evidence of tumor. Widespread form of malignancies of breast, uterus and lung can be observed.

Renal syndrome is characterized by hypokalemic nephropathy, and it occurs in 50% of individuals with ACTH secreting tumors of the lung. Nephrotic syndrome is observed in patients with Hodgkin lymphoma, non Hodgkin lymphoma, malignancies of lung, thyroid, colon, breast, ovary and pancreatic head.

Watery diarrhea and electrolyte imbalance, leads to asthenia, confusion and exhaustion, all characteristic of gastrointestinal syndromes. Severe prostaglandins lead to malabsorption and unavailability of nutrients.

Hematologic syndromes are related to anemia, thrombocytosis, disseminated intravascular coagulation, and leukemoid reactions from several types of cancers. Leukemoid reactions due to immature white blood cells in the blood stream are accompanied by hypereosinophilia and itching.

Cutaneous syndromes are manifested by itching and flushes, alopecia, or hypertrichosis. Blackish pigmentation of the skin usually occurs in patients with metastatic melanomas or pancreatic tumors.

Endocrine syndromes resemble common endocrine disorders. Increased serum and urine cortisol concentrations are common examples of this malignancy.

Neurologic or neuromuscular syndromes relate to cancers and such disorders affect 6% of all patients with cancer. Neuromuscular symptoms mimic common neurological conditions. Myasthenia gravis is a common Paraneoplastic syndrome in patients with thymoma, a malignancy arising from epithelial cells of the thymus.

Paraneoplastic limbic encephalitis is characterized by depression, seizures, irritability and short term memory loss and neurologic symptoms rapidly resemble dementia.

Paraneoplastic cerebellar degeneration causes gait difficulties, dizziness, nausea and diplopia. Sensory neuropathy affects lower and upper extremities and there is progressive memory loss, either symmetric or asymmetric.

Diagnosis

As Paraneoplastic syndromes may evolve over weeks to months, they usually stabilize regardless whether the patient's underlying condition improves or worsens. Since this is the first manifestation of cancer, patients should undergo investigation for cancer. Other diagnoses are membrane disease, dementia, encephalopathy, encephalitis, myelitis, anemia, bone marrow failure, chronic fatigue syndrome, mixed connective tissue disease, polycythemia vera and polymyalgia rheumatica among others.

Complete laboratory tests in blood, urine, cerebrospinal fluid, protein electrophoresis, assays for auto antibodies, Endoscopy and imaging studies including whole body scans and FDG-PET scans are prescribed to detect extremely small tumors especially useful for patients with neurologic diseases.

Treatment of Paraneoplastic Syndrome

Treatment for this syndrome varies depending upon the type and location of tumors. The first option of treatment of the underlying tumor is by therapeutic protocols, a combination of surgery, radiation, chemotherapy. Second therapeutic option is for patients with clearly identifiable antibodies by intravenous immunoglobulins, steroids, or plasma exchange.

Surgical treatment is typically directed toward the underlying neoplasm although some Paraneoplastic disorders may resolve rapidly without surgery on the primary tumor.