What Is Paraneoplastic Myopathy, Paraneoplastic Vasculitis, Paraneoplastic Encephalitis & Paraneoplastic Limbic Encephalitis?
Cancer not only affects the organ in which it develops or in which it gets metastasized. There are other processes happening in the body, in response to the tumor that creates havoc inside the whole body. These symptoms, in combined form, are termed as a paraneoplastic syndrome.
What Is Paraneoplastic Myopathy?
Paraneoplastic myopathy is the condition characterized by the disorders in the muscles and neuromuscular junction in the patients suffering from cancer. The condition is not caused due to the direct involvement of the tumor. This indicates that the condition is not only localized to a particular part of the body rather the effect is wider. There are no minimum criteria for defining the presence of paraneoplastic myopathy, therefore the incidences vary considerably. 75% of the patient suffering from lung cancer has paraneoplastic myopathy1.
Various disorders are associated with Paraneoplastic neuromuscular junction. Lambert-Eaton Myasthenic Syndrome is the condition caused by the autoimmune process. In response to the tumor cells, the immune system of the body gets hyperactivated leading to neuromuscular disorders.
The patient with Lambert-Eaton Myasthenic Syndrome experiences weakness in the muscles especially of upper thigh, neck and upper arms. Muscular force is increased because of the continuous contraction of muscles leading to diagnostic disguise during neurological examinations. 50% of the patient suffered from mild to moderate dysphagia, hoarseness, and dysarthria.
What Is Paraneoplastic Vasculitis?
Vasculitis is defined as the inflammation of blood vessels. It results in significant changes in the anatomical structure of blood vessels that results in alteration of physiological function. This may lead to restricted blood flow in particular tissue or organ leading to necrosis and organ damage.
The mucocutaneous effects due to vascular alterations are seen in paraneoplastic syndrome. It is all estimated that almost 1% of the neoplasms are diagnosed with skin symptoms as their initial signs2. Different types of tumors have different forms of vascular alterations. Vasculitis and erythromelalgia occur in hematological neoplasms while thrombophlebitis and hypercoagulability are seen in patients with solid tumors.
Cutaneous vasculitis may occur in some patients 2-4 years before the diagnosis of the tumor. This includes purpura of the lower extremities, Henoch–Schoenlein purpura, urticarial vasculitis, and erythema elevated diutinum.
Various pathophysiological mechanisms have been elucidated to determine the link between vasculitis and malignancy. These mechanisms include hyperactive immune reactions against endothelium, deposition of cancer proteins on walls of vessels, high level of immune complexes that result in damage of vessels, and endothelial injury due to the high level of circulating cytokines.
What Is Paraneoplastic Encephalitis?
Paraneoplastic encephalitis is considered to be a broad term and may manifest itself as limbic or brainstem encephalitis. During the diagnosis, the cerebrospinal fluid is evaluated and various abnormalities are found. These abnormalities include increased protein concentration, pleocytosis, elevation immunoglobulin G index and oligoclonal bands indicating the presence of inflammatory process3.
It is to be noted that while paraneoplastic encephalitis always occurs in the presence of cancer, the other form, autoimmune encephalitis occurs in the presence or absence of cancer. The condition is most commonly caused due to triggering of the immune system by the tumor. The treatment, apart from treating the tumor, is also directed to either stop the triggering effect of the tumor or to limit its effect on the immune system.
What Is Paraneoplastic Limbic Encephalitis?
Paraneoplastic Limbic Encephalitis is a part of paraneoplastic encephalitis. Patients suffering from this condition experiences confusion, short-term memory loss, behavioral changes, and seizures4. Antineuronal antibodies are present in such patients indicating the role of the immune system in the development of this disease.
Patients suffering from small cell lung carcinoma are most commonly affected with Paraneoplastic Limbic Encephalitis. People with thymomas and Hodgkin’s disease are also affected by this condition. The criteria of Paraneoplastic Limbic Encephalitis include the presence of limbic encephalitis and diagnosis of the tumor within the 5 years of diagnosis with limbic encephalitis.
The paraneoplastic syndrome may lead to various neurological, neuromuscular and hematological problems. These include paraneoplastic myopathy, paraneoplastic vasculitis, paraneoplastic encephalitis & paraneoplastic limbic encephalitis.