Neurological injury, or injury to the brain, spinal cord and/or nerves, results from severe brain or spinal cord trauma. Brain injury is usually due to one of the four major causes:
- Closed head injuries, which occur when the brain strikes the inside of the skull, resulting in bleeding, bruising, swelling, neurochemical changes and increased fluid buildup causing increased pressure within the skull.
- Penetrating injuries are caused when the skull is penetrated in some way. Skull fractures or entry of foreign objects in the brain can damage the functional units of the brain, called neurons.
- Anoxic injuries occur when there is not enough oxygen in the brain, causing brain cells to die.
- Toxic injuries are a result of exposure to toxic chemicals, which can damage or kill brain cells.
Additionally, neurological injuries can result from chronic diseases, such as neuromuscular disorders, stroke, invasive tumors, infection and more. Because the nervous system affects the entirety of the body, outcomes of neurological injury can range from tingling in the fingers and toes, to complete system shutdown. Additionally, treatment is dependent on the type and severity of neurological injury.
Vitamin D has been recognized as having neuroprotective qualities due to the presence of vitamin D receptors in the brain. Research has established associations between vitamin D and cognitive development, cognitive decline, mental health disorders and traumatic brain injury. However, very little recent research has explored the effect of vitamin D status on neurological outcomes in neuro-critical care patients.
In this study, researchers decided to analyze the relationship between vitamin D status and recovery of neuro-critical care patients. A total of 497 critically ill patients hospitalized in a neuro-critical care unit (NCCU) were included in this study. All patients had their serum vitamin D levels measured, underwent a Glasgow Outcome Scale (GOS) test and were present for a three-month follow-up after discharge. The GOS is a test which analyzes the mental and physical capacity of individuals after major cerebral trauma. Scores indicate the following:
2: Persistent vegetative state
3: Severe disability
4: Moderate disability
5: Low disability
This is what the researchers found:
- Of the 497 patients included, 36.6% were considered to be vitamin D deficient (vitamin D status <20 ng/ml; 50 nmol/L).
- A total of 28.6% of the participants had a low GOS score (1, 2 or 3), while the remaining 71.4% had higher GOS scores (4 or 5).
- Vitamin D deficient patients were more likely to return to the NCCU within 30 days of discharge (p=0.014).
- Vitamin D deficient patients had significantly lower GOS scores after the three-month follow-up visit (p=0.023).
The researchers concluded:
“Vitamin D deficiency on admission is associated with a worse 3-month outcome as measured by GOS scores in patients who presented to our NCCU.”
While this study was strengthened by the large populations size and the adjustment of several confounding variables, there are a few limitations to note. First, only one NCCU was utilized, and many of the participants were Caucasian, therefore limiting the generalizability of the findings. Additionally, vitamin D status was only measured at baseline. This makes it difficult to make associations between vitamin D status and neurological outcomes over time. Researchers called for randomized controlled trials to further assess the role of vitamin D on neurological outcomes in critically ill individuals.
Peterson, R. & Cannell, JJ. Low vitamin D status is associated with worse neurological outcomes in patients with severe brain injury. The Vitamin D Council Blog and Newsletter, 8/2017.