Post-mortem toxicological testing for ethanol in body fluids is one of the most important components accompanying forensic autopsies around the world. Such examinations are routinely performed, and their results are often conclusive in determining the circumstances and cause of death [
1]. One of the key steps that can pose difficulties during diagnosis and interpretation of the ethyl alcohol-intoxicated state at the time of death is securing biological specimens for toxicological testing [
2]. For example, in Poland, this should be done according to the Recommendations of the Polish Society of Forensic Medicine and Criminology on the collection of autopsy specimens for toxicological testing [
3]. These guidelines date back to 2012 and have not been updated since, despite suggestions that they are now outdated and need to be revised [
4]. It is also worth mentioning that there is a large amount of ongoing research into the potential use of alternative biological specimens in toxicological analysis, including although not limited to the use of costal cartilage in the post-mortem diagnosis of ethyl alcohol intoxication [
5]. The advantages, disadvantages, and possibility of using CSF as an alternative biological specimen have been recently reviewed [
6].
The primary biological material that should be secured at autopsy is peripheral blood, which is drawn directly from the femoral vein. Unfortunately, under certain circumstances, it is not possible to collect such blood samples, for example, when there has been an extensive injury and/or exsanguination [
7]. An example of an extensive injury, where there is an insufficient amount of autopsy blood for testing, is cases of marked head injuries. This is a result of peripheral blood shunting rather than exsanguination [
8]. It should also be taken into account that blood is susceptible to biochemical and post-mortem changes, and interpreting the result in a putrefied body may need additional testing by simultaneous examination of other body fluids. This procedure aims to exclude the potential presence of endogenous ethanol in the body, which may reach values as high as, and sometimes exceeding, 0.5 g/L of alcohol in the blood, thus carrying the risk of an incorrect assessment [
9,
10]. Therefore, in addition to peripheral blood, simultaneous collection of vitreous humor and/or urine is useful [
9,
10]. There has not yet been any extensive research on the routine use of cerebrospinal fluid collected directly from the spinal cord for this purpose. Data on the use of cerebrospinal fluid collected from different sites for forensic toxicology testing of ethanol content are inadequate as they refer to the determination of ethanol by methods that are not currently used and were subject to a high error risk, such as the classic Widmark method which can give false-positive results in, for example, diabetic patients. We do not dismiss entirely the early studies on ethanol in CFS, but there is some evidence that the classical Widmark method is not specific for ethanol, because some other components (for example, amines, amides, ether, acetone, ketone bodies) can reduce bichromate [
11]. The previous studies that were conducted with gas chromatography (GC) solely involved analysis of cerebrospinal fluid derived from the brain ventricles [
12‐
14]. The above observations are significant since cerebrospinal fluid collected from the ventricular system of the brain differs in biochemical composition from that collected from the spinal cord. Both of these anatomical locations cannot be treated equally until more data is collected [
15]. Fluid from the ventricular system has one significant disadvantage—it is not sufficiently isolated and therefore undergoes greater post-mortem changes than fluid collected from the spinal cord. Cerebrospinal fluid in the subarachnoid space around the spinal column may be more stagnant owing to gravitational effects, whereas in the ventricles, CSF may have a higher cellular turnover. The brain is a highly cellular and metabolically active organ [
15]. Brain tissue decomposes and putrefies right after death. Sometimes, a collection of the clean CSF from the ventricles was not possible because of the highly softened or liquefied consistency of the brain tissues, so it does not necessarily refer to the decay process and the formation of endogenous alcohol in this fluid, but to its contamination and the quality of the sample. Due to the proximity of the brain, the cerebrospinal fluid from the ventricular system may be contaminated more quickly than the one from the spinal cord, even from the top of the spinal column, because fluid from the spinal cord is cleaned as more samples are taken. Collecting CSF from increasingly deeper layers of the spinal canal makes the contaminated sample purer, as deeper layers of fluid are not contaminated due to lack of movement. What is more, when one sometimes tries to collect CSF, it appears to be contaminated with blood. The reason for this contamination may be subarachnoid bleeding or intracerebral hemorrhage [
6]. Certain sites in the body (vitreous, CSF) are more sequestered (or have less glucose) than the vasculature, and accordingly, it is more difficult (or takes longer) for bacteria to get into these areas and then produce ethanol. The authors’ observations show that due to the injuries, the fluid from the ventricles is more often contaminated with blood than fluid from the spinal canal.
These reports provided the inspiration for observations and preliminary studies of cerebrospinal fluid collected directly from the spinal canal specifically to assess its usefulness in the post-mortem diagnosis of ethyl alcohol intoxication.