What Is Paraneoplastic Neuromyopathy And Neuropathy?

Paraneoplastic naturopathy is the condition characterized by the poor nervous system due to cancer. If cancer affects the nervous system associated with muscles or the neuromuscular junction, the condition is termed as paraneoplastic neuromyopathy.

Paraneoplastic syndrome is the condition caused due to the presence of cancer cells in the body. The condition is not because of cancer, rather it is caused by the chemicals and hormones secreted by the tumor cells. Paraneoplastic syndrome is also caused due to the immune response of the body against cancerous cells. People suffering from the cancer of lungs, ovaries, breasts and lymph nodes are more at risk for developing the paraneoplastic syndrome. Cancer may lead to autonomic disturbances at any time relative to cancer diagnosis¹.

Paraneoplastic neuropathy or paraneoplastic neurological disease is the group of diseases related to the nervous system that is caused because of the presence of certain antibodies. It has been noted that the overall incidence of paraneoplastic neuropathy diseases is rare, however, the disease also depends upon the type of cancer. In a study, it has been found that 50% of the patients suffering from ovarian epithelium neoplasm were also having peripheral neuropathy². Further, 45% of patients with small cell lung cancer were suffering from peripheral neuropathy.

Various causes have been considered for paraneoplastic neuropathy diseases. These include toxins, nutritional deficiency, autoimmunity, and viruses. However, there is no definite reason to be found that may exactly illustrate the cause of peripheral neuropathy in patients with cancer. It has been seen in many patients that autoantibodies are absent in the patient with cancer although they are suffering from the paraneoplastic nervous disease.

To avoid confusion with other neuropathies, a classification for paraneoplastic neuropathy is required. Paraneoplastic neuropathies include:

• There is a demonstration of a direct link between cancer and neuropathy,
• Seronegative sensory neuropathy with well establishes the paraneoplastic origin, but autoantibodies are absent.
• Although there was no spontaneous recovery of neuropathy, however, with the treatment of cancer, the severity of neuropathy reduces.
• Within 2 years of cancer diagnosis, if there is any neuropathy diagnosed it may be a paraneoplastic neuropathy³.

Recent researches throw light on the possible mechanism through which paraneoplastic syndrome or to be specific, paraneoplastic neuropathy occurs. Carcinoma leads to the breakdown of immune tolerance because of the expression of self-antigen of the nervous system by tumor cells. This leads to the activation of T-lymphocytes and production of onconeural autoantibodies. In other types of cancer, immune system to plays a major role in paraneoplastic neuropathy. In thymoma, autoreactive regulatory T cells are produced and tumoral epithelial self-antigen is expressed.

The bigger picture, paraneoplastic neurological syndrome, leads to varied symptoms related to the nervous system. This leads to encephalitis in which the brain gets inflamed, ataxia, myoclonus, psychiatric disturbances and myasthenia gravis. There is no fixed rate of progression of the neurological syndrome. Symptoms may progress at a very rapid rate or may manifest themselves slowly⁴.

Patients with cancer do not have significant incidences of paraneoplastic neuromyopathy. The study found that only 7% of patients with cancer are found with significant neurological symptoms⁵. However, it has been found that although the significant neurological symptoms were in fewer patients, more than half of the patients were with proximal limb weakness. Other symptoms related to a neuromuscular junction in patients with cancer include proximal muscle weakness, depressed tendon reflexes, and mild sensory disturbances. Rarely, patient with cancer may also show the sign of the myasthenic myopathic syndrome.

In one case, neuropathy and sicca syndrome was found in one patient which was later on diagnosed with small cell bronchial carcinoma. This paraneoplastic neuromyopathy was found to be non-responsive with steroidal therapy. The condition was dramatically improved by administering cyclophosphamide⁶.

Paraneoplastic neurological syndrome occurs during cancer. The exact cause of the condition is not known however, the immune system plays a vital role in the pathophysiology of this condition.

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Also Read:

• Paraneoplastic Syndrome: Causes, Symptoms, Treatment, Pathogenesis, Types