Sodium is important for the function of all of the cells in the body because it is an electrolyte. Nerve cells are particularly sensitive to the amount of sodium in the blood because they need electrolytes to function properly. Too much or too little sodium can cause problems with the nerves in your brain and elsewhere in your body.
Sodium and Neuron Function
Nerve cells, also known as neurons, require small electrical currents to work properly. To generate these electrical currents, your neurons control the levels of different electrolytes inside and outside of the cell. Neurons have special channels that allow sodium ions to flow into the cell; these channels are initially opened when the neuron receives chemical signals that tell it to generate its electrical current. The influx of sodium ions generates a small positive charge within the nerve cell, which causes sodium ions elsewhere in the neuron to open. This creates a small electrical current known as an action potential that is responsible for nerve cell activity.
High Sodium and Nerve Problems
If you have too much sodium in your blood, you have a condition known as hypernatremia. Hypernatremia can cause a variety of symptoms, including brain problems, because the excess of sodium disrupts the natural electrical currents of your nerves. Hypernatremia is usually caused by dehydration, resulting in the sodium in your blood becoming concentrated. Neurological signs of hypernatremia include lethargy, irritability, changes in mental status, restlessness, seizures, and twitching or spasms.
Hyponatremia and the Brain
Although too much sodium can be dangerous for your brain, too little sodium can also disrupt nerve function. Hyponatremia can be caused by kidney problems, congestive heart failure, the use of diuretics, drinking too much water, severe diarrhea and vomiting, liver cirrhosis and using some medications. Symptoms of hyponatremia include headache, confusion, seizures, fatigue and unconsciousness.
Normally the sodium concentration in your blood will be between 135 and 145 milliequivalents per liter of blood. Too much or too little sodium can cause serious health problems; if you are concerned about the amount of sodium in your body, talk to your doctor. Blood tests can measure the amount of sodium in your blood and determine if you are at risk of having brain problems due to sodium imbalance.