What Is Paraneoplastic Cerebellar Degeneration?

Cerebellar degeneration is defined as the loss of neurons in that particular region of the brain that controls the muscular function and balance. Because of malignancy, this degeneration occurs, and the condition is termed as Paraneoplastic cerebellar degeneration.

Paraneoplastic cerebellar degeneration (PCD) is a disorder of that particular area of the brain (cerebellum) that is responsible for coordinating voluntary movement. It is a disease that is associated with the tumors such as breast cancer, lung cancer and cancer of the nervous system. PCD is caused when tumors release various chemicals and also the immune system acts against these cancerous cells. It is a rare disease occurs in 1% cancer patient. According to current studies killer, T Cells or cytotoxic CD8+ T lymphocytes are major mediators of antibody injury¹.

Symptoms of paraneoplastic cerebellar degeneration can rapidly develop in the patients or they may develop slowly.

Encephalitis: It is a condition caused by antibodies and viruses. The condition is characterized by inflammation in the brain and cause problems with memory, cognition, and/or altered levels of consciousness.

Ataxia: Ataxia means impaired coordination or balances voluntary movements such as walking. This is caused because of damage in the brain, muscles or nerves.

Neuropathy: Neuropathy is a condition in which the nerve gets damaged due to disease or injury.

Myoclonus/Opsoclonus: It is condition commonly occurring in patients with tumors and viral infection. It is normally caused by children due to malignancy.

Myasthenia Gravis: This condition is characterized by the extreme weakness of muscles include those that assist in breathing².

Two types of tests are available for diagnosis of paraneoplastic cerebellar degeneration:

1. Laboratory test
2. Imaging technique

Laboratory Test: Laboratory tests include:

Blood Test. The blood test is done for the identification of antibodies that are commonly associated with the paraneoplastic cerebellar degeneration.

Spinal Tap/Lumbar Puncture: In this test, a specially trained surgeon administers a needle in the brain and removes a little amount of CSF. PCD antibodies are tested in the obtained sample. Presence of PCD antibodies in the fluid gives strong evidence of paraneoplastic cerebellar degeneration.

Imaging Techniques: imagine test is used to found tumors in the brain there are some imagine test including;

Computerized Tomography (CT): CT of the abdomen or chest is done to evaluate the primary malignancy in case there is a presence of anti-Yo antibodies.

Magnetic Resonance Imaging (MRI): MRI can be used to determine the cerebellar atrophy in advanced stages. MRI with contrast can be done to rule out any structural or infectious causes.

Positron Emission Tomography (PET): PET may also be used to evaluate the extent of damage in the brain due to cerebellar degeneration.

The treatment of paraneoplastic cerebellar degeneration is based on the condition of the patient and the severity of the disease. The doctor may prescribe some medications to treat paraneoplastic syndrome such as:

Medications To Improve Muscular Activity: These drugs help in decreasing the symptoms of paraneoplastic cerebellar degeneration. These include^{2, 3}– diaminopyridine and pyridostigmine.

Anti-Seizure Medications: These drugs help to maintain the condition by controlling the seizure associated with the paraneoplastic cerebellar degeneration.

Corticosteroids: Corticosteroid helps in the treatment of inflammation. However, it is to be noted that the chronic administration of corticosteroid may lead to side effects.

Immunosuppressants: These drugs help to slow the progression of the disease. Drugs for this purpose include azathioprine (Imuran) and cyclophosphamide.

Intravenous Immunoglobulin: Intravenous immunoglobulin helps improve the neurological condition in patients with late onset of paraneoplastic cerebellar degeneration.

Plasmapheresis: During this process, the plasma is separated out from the blood while retaining blood cells. This helps in removing the unwanted antibodies from the system⁴.

Cerebellar degeneration due to malignancy occurs because of the chemicals and hormones secreted by tumor cells and also the trigger of the immune system due to malignancy. Various other effects on the nervous system occur and are termed as Paraneoplastic Neurological diseases.

Refrences

1. https://www.dizziness-and-balance.com/disorders/central/cerebellar/pcd.htm
2. https://rarediseases.org/rare-diseases/paraneoplastic-neurologic-syndromes/
3. https://www.ncbi.nlm.nih.gov/pubmed/16773214
4. https://www.mayoclinic.org/diseases-conditions/paraneoplastic-syndromes/diagnosis-treatment/drc-20355691