Neurological paraneoplastic syndromes are disorders of the nervous system that occur in some people struggling with cancer. However, they are not caused by the tumor's local division or its metastasis to the nervous system. What are the exact causes of neurological paraneoplastic syndromes? How to recognize their symptoms? What is their treatment?

Neurological paraneoplastic syndromes (NSA)are disorders of the nervous system that appear in some cancer patients, but are not caused by the local action of the tumor (infiltration, pressure) or its metastasis to the nervous system, toxic effects of anti-cancer drugs, vascular lesions or coexisting infections.

Neurological paraneoplastic syndromes are diagnosed in less than 1% of cancer patients. Until recently, NSA was diagnosed only in people with neoplasms developing outside the nervous system, however, a case of NSA in a patient with oligodendroglioma, i.e. a brain tumor originating from oligonuclear glial cells, has been described.

Neurological paraneoplastic syndromes - causes and risk factors

The causes of neurological paraneoplastic syndromes are unknown, but it is believed that their mechanism of formation is related to the production of anti-tumor antibodies. Normally, a person's body produces antibodies to fight cancer cells. However, in rare cases, they also mistakenly attack the structures of the nervous system - these areonconeural antibodies.

However, not all patients have onconeuronal antibodies detected despite the diagnosis of NSAID. This suggests that there are other causes of this syndrome as well. Doctors speculate that metabolic mechanisms may play a role in the development of NSAID. Influence of toxic agents or viruses is also possible.

It is also known that the risk of developing NSAIDs is higher in people with certain cancers, such as small cell lung cancer, neuroblastoma, and thymoma. Age may also be a risk factor - paraneoplastic neurological syndromes usually develop in middle-aged people.

Neurological paraneoplastic syndromes - types

Classic neurological paraneoplastic syndromesNon-classical neurological syndromesparaneoplastic
  • inflammation of the limbic system
  • subacute degeneration of the cerebellum
  • brainstemitis
  • opsoklonie / mioclonie
  • subacute sensory neuropathy
  • chronic pseudo-gastrointestinal obstruction
  • Lambert-Eaton syndrome
  • dermatomyositis
  • paraneoplastic retinopathy
  • subacute necrotic myelopathy
  • motor neuron disease
  • demyelinating neuropathies
  • axonal loss neuropathies
  • neuromyotonia
  • polymyositis

Neurological paraneoplastic syndromes - symptoms

  • muscle weakness
  • movement disorders
  • difficulty maintaining balance
  • sensory disturbances, paresis
  • epileptic seizures
  • speech disorders, e.g. slurred speech
  • visual disturbances, e.g. sudden deterioration of vision
  • confusion, disturbance of consciousness

The symptoms of NSA also include those that suggest mental illnesses, e.g. memory impairment or amnesia, personality changes, changing the behavior to atypical (hyperactivity and aggression or vice versa - depressed mood or even depression), hallucinations, delusions, etc.

Important

The symptoms of IBD very often precede the symptoms of cancer

U 80 percent in patients, the symptoms of neurological paraneoplastic syndromes precede those of the primary neoplasm. In most cases, the primary neoplasm is detected 4-6 months after the onset of the symptoms of NSAID. After 2 years, the risk of cancer detection decreases, and after 4 years it is very low.

Neurological paraneoplastic syndromes - diagnosis

Determining the presence of onconeuronal antibodies in the blood of patients is a key factor in the diagnosis of NSAID. Well-defined onconeuronal antibodies (i.e. those found in well-characterized neurological syndromes and very often associated with the presence of cancer) are anti-Hu, anti-Yo, anti-Ri, anti-CV2, anti-Ma / anti-Ta and anti -amphyphysin. For example, the presence of anti-Yo antibodies is found in patients with paraneoplastic degeneration of the cerebellum and in the course of ovarian and breast cancer. In turn, anti-amphiphysin antibodies are detected in patients with rigid human syndrome and accompany small cell lung cancer and ovarian cancer.

U 5-10 percent patients have atypical, uncharacterized onconeuronal antibodies.

Supportive tests are neuroimaging tests, such as computed tomography and resonance imagingmagnetic, PET scan.

During the diagnosis, the doctor should exclude other diseases that manifest themselves similarly to NSA, such as cerebellar syndromes, neuropathy, myasthenic syndrome of a different origin, and skeletal muscle diseases.

Neurological paraneoplastic syndromes - treatment

If it turns out that the cancer is responsible for the inappropriate response of the immune system, the first thing to do is to remove it. The next step is to administer immunosuppressants to the patient, which will "silence" the immune system. Then, the doctor may order plasmapheresis, a procedure to remove anti-neuronal antibodies from the blood.

Bibliography

Michalak S.,Classification and recognition of neurological paraneoplastic syndromes , "Polski Przegląd Neurologiczny" 2008, vol. 4, no. 4

Category:

Neurology