Water intoxication: severe hyponatremia and brain injury

Water intoxication may occur when someone drinks so much water in a short time that the kidneys cannot excrete the excess water quickly enough. This can lead to hyponatremia: a concentration of sodium in the blood that is too low.

Hyponatremia can also have other causes. For example, certain diseases, medications, or disturbances in fluid and hormone balance can cause it. Water intoxication is therefore one possible cause of hyponatremia.

Severe hyponatremia can have major consequences for the brain and be life-threatening in acute situations.

 

What happens in the brain?

Sodium plays an important role in the fluid balance between the blood and the body cells and in the functioning of nerve and muscle cells.

When the sodium concentration in the blood drops sharply, water moves into the cells due to differences in osmotic pressure. Brain cells may also swell as a result. If hyponatremia develops rapidly, the brain has insufficient time to adapt to this change. Brain edema can then develop.

The brain is enclosed within the skull. Severe brain edema can therefore lead to increased pressure within the skull and disruption of brain functions.

 

 

Neurological symptoms

The symptoms depend, among other things, on the severity of the hyponatremia and the speed at which it developed.

Possible neurological symptoms include:

• headache
  
• nausea and vomiting
  
• confusion and disorientation
  
• drowsiness or reduced consciousness
  
• epileptic seizures
  
• coma

In cases of very severe cerebral edema vital brain functions can be threatened. In extreme cases, herniation of brain tissue can occur, resulting in death.

Severe hyponatremia with neurological symptoms is therefore a medical emergency.

Acute and chronic hyponatremia

It makes a difference whether hyponatremia developed rapidly or gradually.

In acute hyponatremia, the sodium concentration drops in a short time. The brain then has little time to adapt. Consequently, the risk of cerebral edema and acute neurological complications is greater.

In chronic hyponatremia, brain cells partially adapt to the altered osmotic conditions. As a result, cerebral edema may be less prominent. However, this adaptation makes the brain vulnerable if the sodium concentration is subsequently increased too rapidly.

 

Treatment

The treatment depends on the cause, severity, and duration of the hyponatremia, as well as the symptoms present.
In the event of severe neurological symptoms, treatment with a concentrated saline solution via an intravenous infusion may be necessary. During this process, the sodium concentration is closely monitored.
The treatment requires careful attention. Severe acute hyponatremia must be treated sufficiently quickly to reduce the risk of cerebral edema. Particularly in cases of severe or long-standing hyponatremia, it is essential to prevent the sodium concentration from rising too rapidly.

Osmotic demyelination syndrome (ODS)

Osmotic demyelination syndrome (ODS) is a rare but serious neurological complication. ODS can develop primarily when severe, long-standing hyponatremia is corrected too quickly.

In ODS, myelin is damaged. Myelin forms the insulating layer around nerve fibers and is important for the conduction of nerve signals.
The damage can occur in various places in the brain. When the pons, a part of the brainstem, is primarily affected, it is referred to as central pontine myelinolysis. This term was used more frequently in the past.

ODS also includes myelination outside the pons.

 

 

A characteristic feature is that neurological deterioration may occur with a delay. The patient may initially improve after treatment and subsequently develop new neurological symptoms in the days that follow.

Possible symptoms and consequences include:

• muscle weakness or paralysis
  
• problems with speech
  
• swallowing problems
  
• movement disorders
  
• confusion and changes in consciousness
  severe and sometimes permanent neurological impairments.

In severe cases, ODS can lead to coma or death.

 

Locked-in syndrome

In rare cases, severe damage to the pons can lead to locked-in syndrome.

In classic locked-in syndrome, the patient is conscious, but virtually all voluntary movements have ceased and he or she can no longer speak. Vertical eye movements and blinking may be preserved and sometimes used to communicate.

Locked-in syndrome is not simply the result of brain swelling from water intoxication. It can arise, among other things, from severe pontine damage caused by ODS.

 

Can severe hyponatremia cause permanent brain damage?

Yes. After very severe hyponatremia, permanent brain damage may occur, for example as a result of severe cerebral edema, oxygen deprivation during a critical situation, or ODS.

Not everyone suffers lasting consequences. Some people recover completely. In others, neurological or cognitive impairments persist.

Possible brain damage
Possible consequences of permanent brain damage
The consequences vary greatly from person to person and depend on, among other things, the location and extent of the brain damage.

Possible consequences are:

Cognitive consequences

• problems with attention and concentration
  
• memory problems
  
• delayed information processing
  
• problems with planning, organizing, and maintaining an overview
  
• becoming mentally fatigued more quickly

 

Physical and neurological consequences

• muscle weakness or paralysis
  
• problems with coordination and balance
  
• movement disorders
  
• problems with speaking or swallowing
  
• severe fatigue

Behavior and emotions
Depending on the brain injury, changes may also occur in behavior, emotions, and the ability to regulate them.

The symptoms that occur and the course of recovery vary from person to person. Moreover, symptoms alone cannot demonstrate that someone has sustained brain damage due to hyponatremia. For this, the medical history, the course of the acute situation, and the results of medical and neurological examinations are important, among other things.

 

Preventing Water Intoxication

Water is essential for the body, but drinking extremely large amounts in a short time can be dangerous. The risk can arise, for example, during prolonged physical exertion when very large quantities of water are consumed, with certain medical conditions or medications, and in situations where someone drinks excessive amounts of water.
The amount of fluid a person needs varies per person and per situation. Heat, physical exertion, diet, illness, medication use, and kidney function all play a role in this. Therefore, a fixed amount of water per day is not suitable for everyone.

 

When to seek medical help?

Immediate medical help is necessary in the event of possible water intoxication combined with neurological symptoms such as severe confusion, increasing drowsiness, epileptic seizures, or loss of consciousness.

Severe acute hyponatremia can develop rapidly. Trying to correct sodium concentration yourself by, for example, using a lot of salt is not safe. Severe hyponatremia must be medically assessed and, if necessary, treated with monitoring.

 

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