What is Cerebral Salt Wasting Syndrome?
Cerebral salt wasting (CSW) is one possible reason for low sodium levels in the body. It can occur when there’s a disorder related to the brain or nervous system. In this condition, low body sodium levels coupled with high sodium levels in urine, as well as low blood volume are observed. It’s currently a topic of discussion among medical professionals, whether this condition is unique or if it’s a specific version of another condition called Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH).
The reason it’s crucial to determine whether it’s CSW or SIADH is because they require completely different treatments. If it’s CSW, the patient will need fluids and additional sodium. In contrast, if it’s SIADH, fluid intake will need to be restricted.
Usually, cerebral salt wasting gets better within a few weeks to months from when it starts. However, it can become a long-term problem. The main theories about why this happens involve the release of a certain brain chemical (Brain Natriuretic Peptide or BNP) or possible damage to a part of the brain called the hypothalamus, resulting in disruption of the sympathetic nervous system, which controls certain body functions.
What Causes Cerebral Salt Wasting Syndrome?
We don’t fully understand why cerebral salt wasting (a condition where the body loses too much salt and water) occurs. Usually, it seems to happen after damage to the central nervous system, which is the part of your body that includes the brain and spinal cord. It’s most common after a specific type of stroke called an aneurysmal subarachnoid hemorrhage.
We’re not exactly sure why cerebral salt wasting happens more often after an aneurysmal subarachnoid hemorrhage, as compared to another type of injury called a traumatic subarachnoid hemorrhage, or other damage to the central nervous system. And we also don’t know why it’s rare after other types of injury or disease. More research is needed to understand these things better.
Risk Factors and Frequency for Cerebral Salt Wasting Syndrome
Cerebral salt wasting (CSW), a condition that still sparks debate among medical professionals, is difficult to track accurately in terms of its incidence and prevalence. It’s most frequently seen following an aneurysmal subarachnoid hemorrhage, which is a type of stroke caused by bleeding in the space surrounding the brain. However, CSW can also occur after other types of central nervous system damage.
- CSW has been observed in cases like post-operative recovery from pituitary tumor or acoustic neuroma surgery.
- It has been reported after calvarial remodeling, a type of cranial surgery.
- Occurrence of CSW is found in glioma, a type of brain tumor.
- Infections such as tuberculous meningitis and viral meningitis may lead to CSW.
- It can be associated with metastatic carcinoma, a type of cancer that has spread from the place where it started.
- Cranial trauma or head injuries can also trigger it.
Some studies suggest that CSW may be responsible for up to a quarter of severe cases of low sodium levels(hyponatremia) that occur after aneurysmal subarachnoid hemorrhage. CSW has also been reported in case studies of other types of central nervous system damage. However, reliable incident and prevalence rates for CSW in patients without central nervous system insult haven’t been established.
Signs and Symptoms of Cerebral Salt Wasting Syndrome
Cerebral salt wasting is a condition that often shows up as low sodium levels in the body after bleeding around the brain due to a ruptured aneurysm. A few days after this bleeding occurs, the patient’s sodium levels start to decrease while the amount of sodium in their urine goes up. The patient also loses fluids, becoming both low in sodium (hyponatremia) and fluids (hypovolemic). This condition generally gets better with treatment over a few weeks to months, and it’s usually not necessary to continue treatment over the long term.
Besides occurring after an aneurysm, cerebral salt wasting has also been reported to happen after surgeries on the central nervous system, such as operations on the pituitary gland, vestibular schwannoma removals, and skull reshaping procedures. This condition can also develop following a head injury, a brain tumor, or infections in the central nervous system.
Testing for Cerebral Salt Wasting Syndrome
If there’s a suspicion of cerebral salt wasting (CSW) or the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), it’s critical to determine which one you have. These two conditions might seem similar, but their treatments are completely opposite. A basic metabolic panel (a type of blood test) to check your body’s level of sodium is an excellent start to evaluate for CSW. If your sodium level is below 135 meq/L (milliequivalents per liter), you might be dealing with hyponatremia, a condition characterized by low sodium levels.
Other tests that might be done include urine checks for sodium and osmolality (how concentrated the urine is). If you’ve got CSW, urinary sodium can be above 40 meq/L and urine osmolality above 100 mosmol/kg. You might also experience symptoms like low blood pressure, reduced central venous pressure (the pressure of blood in the heart), lacking skin elasticity or an increased proportion of red blood cells in your blood (a condition known as high hematocrit).
On the other hand, with SIADH, you might also experience hyponatremia and increased urine sodium, just like with CSW. However, a distinctive aspect of SIADH is that you retain an excess amount of water, which can lead to a normal or high volume of fluid in your body compared to the reduced fluid volume seen in CSW.
There are also other potential causes of low sodium levels in your body, such as excessive drinking, kidney disease, taking diuretics (medications that help get rid of excess salt and water from your body), heart failure, low thyroid hormone levels, cancer, hormone deficiency or false hyponatremia (where sodium levels appear abnormal due to elevation of other substances in the blood). Sometimes, CSW is only confirmed after these other possibilities have been ruled out through lab tests showing low sodium levels in the blood along with increased urinary sodium levels.
Treatment Options for Cerebral Salt Wasting Syndrome
It’s crucial to have an accurate diagnosis when treating cerebral salt wasting (CSW) and Syndrome of Inappropriate Secretion of Antidiuretic Hormone (SIADH). Both conditions can result in an imbalance of sodium in the body, but require different treatment methods.
Cerebral salt wasting usually happens after an illness, such as bleeding in the brain due to a ruptured brain aneurysm. Therefore, the first action is to treat the underlying cause. Then, the patient needs to be rehydrated while the low sodium levels in their blood – a condition known as hyponatremia – are addressed. For less severe cases, the patient is typically given isotonic saline, a balanced salt solution that helps restore body fluids and correct sodium levels. More severe cases may need a more concentrated salt solution known as hypertonic saline or salt tablets. Some doctors may also suggest limiting the intake of water and using a steroid medication known as fludrocortisone.
It’s important to monitor the patient’s blood sodium level closely during this time. If sodium is corrected too quickly or excessively, it could lead to high sodium levels – hypernatremia – which may cause symptoms like muscle twitching, lethargy, seizures, or could even be life-threatening. Additionally, correcting sodium levels too swiftly in chronic low-sodium conditions could risk a rare but serious brain condition called central pontine myelinolysis. Therefore, medical professionals usually aim to correct sodium levels slowly and carefully.
The diagnosis becomes crucial when distinguishing between cerebral salt wasting and SIADH. While both conditions involve an imbalance of sodium, the treatment methods are fundamentally different, and using a wrong approach could aggravate the patient’s condition. For SIADH, common treatments involve fluid restriction, hypertonic saline, demeclocycline, and/or furosemide. However, if a patient has cerebral salt wasting, where they are dehydrated or have insufficient blood volume, these treatments could potentially worsen their condition.
What else can Cerebral Salt Wasting Syndrome be?
It’s important to understand the difference between two conditions – cerebral salt wasting and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Both of these medical issues share some commonalities like low sodium levels in the blood, high sodium levels in the urine, concentrated urine, and lack of swelling. However, the main thing that sets them apart is that patients with cerebral salt wasting are typically dehydrated, while those with SIADH range from having normal to above-normal body fluid levels.
There are several possible reasons why someone might develop cerebral salt wasting, such as:
- A head injury
- A brain tumor
- A stroke
- Brain surgery
- Bleeding within the brain
- Repair of craniosynostosis (a condition where the bones in a baby’s skull join together too early)
- Tuberculous meningitis (a serious bacterial infection that affects the brain)
