Neurotoxicity

Neurotoxicity occurs when the exposure to natural or manmade toxic substances (neurotoxicants) alters the normal activity of the nervous system. This can eventually disrupt or even kill neurons, key cells that transmit and process signals in the brain and other parts of the nervous system.

Causes

Neurotoxicity can result from exposure to substances used in chemotherapy, radiation treatment, drug therapies, and organ transplants, as well as exposure to heavy metals such as lead and mercury, certain foods and food additives, pesticides, industrial and/or cleaning solvents, cosmetics, and some naturally occurring substances.

Signs and Symptoms

Symptoms may appear immediately after exposure or be delayed. They may include:

• limb weakness or numbness
• loss of memory
• vision loss
• loss of intellect
• headache
• cognitive and behavioral problems
• sexual dysfunction.

Individuals with certain disorders may be especially vulnerable to neurotoxicants.

Diagnosis

Tests can be done to look for substances in the blood that can cause neurotoxicty. For example, the patient's blood can be analyzed for metals, certain drugs, food additives, pesticides, or solvents. A thorough history is taken in order to try and determine the source of the toxin. Other blood tests may be done such as a complete blood count (CBC) and electrolyte analysis ( Which checks the levels of substances such as sodium, potassium, and calcium). These tests can also help the doctor determine the source of the toxin.

Treatment

Treatment involves eliminating or reducing exposure to the toxic substance, followed by symptomatic and supportive therapy.

Expected Outcome

The prognosis depends upon the length and degree of exposure and the severity of neurological injury. In some instances, exposure to neurotoxicants can be fatal. In others, patients may survive but not fully recover. In other situations, many individuals recover completely after treatment.

Clinical Trials

• A Pilot Study of Dextromethorphan for the Prevention and Treatment of Methotrexate Neurotoxicity
• Relationship Between Platinum Levels in the Blood and Neurotoxicity in Patients Who Are Receiving Oxaliplatin for Gastrointestinal Cancer
• Use of FACT-GOG/NTX Questionnaire in Peripheral Neurotoxicity & Validation of a French Version of This Questionnaire

Research

The NINDS supports research on disorders of the brain and nervous system such as neurotoxicity, aimed at learning more about these disorders and finding ways to prevent and treat them. Scientists are investigating the role occupational or environmental toxicants have on progressive neurodegenerative disorders such as Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and dementia. Also being studied are the mechanisms that trigger neuroimmune responses in the central nervous system and the possibility that some brain disorders in children may occur when environmental triggers interact with genes.

Other Resources

• Neurotoxic Chemical Effects Information