The tongue protrusion in post-mortem fire

Abstract

Burned bodies raise relevant issues for forensic patologist and odontologist both for the identification and the cause of death and possible vital burning.. The tongue protrusion is regularly investigated for the death caused by strangulation or hanging, whilst seems to be overlooked in case of charred remains as the significance of this sign is still discussed. Different mechanims are hypothized in literature to explain the toungue protrusion both for vital and non-vital burning. This paper retrospectively evaluates some cases of carbonized corpses examined at the Forensic Pathology service of the University of Florence. The tongue protrusion shows a high occurrence both in vital (100%) and non-vital fires (66%). The involvement of a forensic odontologist in the cadaver examination result to be limited to one third of the cases. In two non-vital cases the tongue was described as protruded and clenched between the dental arches. The rigor of the genioglossus induced by the heat could explain the phenomenon. Further research on fire fatalities is required to analyze the tongue bleeding as a possible parameter to discriminate the vital by the non-vital tongue protrusion. Moreover, the mechanism at the origin of vital and non-vital tongue protrusion, the different position of the tongue (protruded from an open mouth, protruded and clenched between the dental arches, etc.) in different death circumstances, should be furtherly investigated with a meaningful collaboration between forensic pathologists and odontologists for a complete registration and interpretation of all the mouth originated evidence.

Introduction

Burned bodies are a real challenge for forensic patologist and odontologist charged of the answer to the crucial question of the identification of the cause of death and possible ante-mortem (AM) exposition to the fire. (1, 2)

According to previous literature, the most reliable signs of vitality include soot deposits in the respiratory or digestive tract, a blood level of carboxi-hemoglobin (COHb) or HCN. (3-6) An unclear or inconclusive evidence of vitality is present in some cases due to the specific dynamic of fire (e.g. “flashfire”).

The tongue protrusion is regularly investigated in case of death caused by strangulation or hanging, but tends to be overlooked in case of charred remains as the significance of this sign in the determination of the cause of death or burning vitality is still discussed. Bernitz reported a significant prevalence of tongue protrusion in cases of vital burning and concluded for the evidence of a correlation between the survival time and a protruded tongue. (7) Hejna and Janik hypothesized the occurrence of a vital bleeding of the tongue (8), actually described in different kind of death (hanging, strangulation and burning), as a possible explanation for the protrusion. Bohnert and Hejna discussed cases of protruded tongue in non-vital fire and outlined alternative mechanisms for the vital and post-mortem tongue protrusion following fire exposition.⁹This paper retrospectively evaluates cases of charred bodies with tongue protrusion in case of vital or non-vital fire examined at the Forensic Pathology service of the University of Florence, Italy.

MATERIALS AND METHODS:

The sample consisted of thirty-four reports written by forensic pathologists charged by the Public Prosecutor to perform a judicial autopsy addressed to establish the cause of death and sometimes the identity of the subjects. No further documentation with the exception of the anonymous reports and the attached pictures was available to the authors and no further examinations were possibly obtained and conducted on the bodies other than those performed by the charged pathologists. The following data were collected from the reports examined:

• 1- age and gender of the individual

• 2- the extent of the burns (Table 1) that was assessed according to the Crow-Glassman Scale (CGS)

• 3- blood values of COHb and HCN

• 4- soot deposits in the respiratory or digestive tract

• 5-the involvement of a forensic odontologist in the case

• 6- the tongue protrusion

Table 1. Crow-Glassman Scale (CGS).

CGS-1	Death by inhalation of toxic fumes. First and second degree burns on the body. Visual identification is still possible.
CGS-2	Significant carbonization of the body. Possible mutilation of small bones of the hands and feet. Identification can be performed through dental records and /or DNA .
CGS-3	Significant carbonization of the body, with the skull still intact. Possible mutilation also of the limb bones. Possible identification through dental records and /or DNA.
CGS-4	Total fragmentation of the skull and further mutilation of the limb bones. Possible identification through dental records and /or DNA.
CGS-5	Skeletal remains. There are no remaining soft tissues and any remaining skeletal component is fragmented. The identification of the remains is highly problematic.

RESULTS

The age of the sample ranged from 5 to 90 years; the females individuals were 7 and the males 27. Of the 34 examined cases, only 11 reports included a detailed description of the tongue, whilst in 25 cases the tongue position was probably not detectable due to the severe destruction of the jaws or the tongue itself (e.g. charred bodies with open mouth).

The Tables 2-3 show the blood values of COHb, HCN and soot deposits in the digestive or respiratory tract in the cases with protruded tongue. Only in the 38% of the cases a forensic odontologist was involved in the examination. Even if the number of cases in which the position of the tongue was detectable or reported by the pathologist is small, the protrusion of the tongue was present in all the vital burnings; two in three post-mortem fire cases presented tongue protrusion. Hence, the tongue protrusion shows a high occurrence both in vital (100%) and non-vital fires (66%) in our limited sample.

Table 2. Frequence of the tongue, vital signs, CGS and the intervention of a FOd.

	Tongue protrusion	No tongue protrusion	Tongue position not detectable
Soot deposits	6	/	16
No soot deposits	4	1	5
COHb <10%	5	1	16
COHb >10%	5	/	7
CGS 1-2	2	1	9
CGS 3-5	8	/	14
Intervention of the forensic odontologist (FOd)	4	/	9

Table 3. Fire-fatalities. Correlation between tongue protrusion and cause of death.

Death due to:	Tongue protrusion	No tongue protrusion	Tongue position not detectable
COHb - open place - closed place	/ 2	/ /	/ 11
HCN - open place - closed place	/ 1	/ /	/ 1
COHb and HCN	1	/	2
Fire- high temperature	4	/	4
Multiple factors	2	1	5

Two badly burned cadavers were found in the ground after a post-mortem fire caused by an helicopter accident. The male bodies were identified as the pilot and passenger, respectively 61 and 54 years old. During the autopsy the forensic pathologist found severe traumatic lesions in both bodies (fractures of vertebrae, ribs, skull base, long bones, etc), and the tear of the aorta thoracic and abdominal tract respectively. The forensic pathologist concluded for immediate death following the precipitation. In both cases the tongue was described as protruded and clenched between the dental arches . The values of COHb and HCN were negative and no soots deposit were found in the respiratory or digestive tract. As shown in Table 1, both cadavers presented extended burns (CGS 4).

DISCUSSION

The tongue protrusion is a common finding in some deaths for asphyxiation (e.g., hanging, incomplete strangulation), and the compression of neck tissues and vessels is considered the cause of the phenomenon. A protruded tongue, clenched between the dental arches, can be frequently observed also in carbonized cadavers and the question if this sign could be considered an useful hint for the discrimination of vital and non-vital burning is still an unresolved matter of discussion in the Literature. (7-11) Different mechanisms have been hypothesized as the cause for the lingual protrusion in vital burning and post-mortem fire cases.

Bernitz found a correlation between the tongue protrusion and the occurrence of a vital burning. (7) According to his causal hypothesis, the protrusion is attributed to the laryngospam caused by a temperature higher than 150 °C and hyperventilation. Nikolic criticised Bernitz's conclusions saying that they were based on an incorrect statistical analysis and found a tongue protrusion in two post-mortem burning cases.

Bohnert and Hejna found that the tongue protrusion is not correlated to vital burning or heat-induced shrinkage of the cervical soft tissue. (9)

Different mechanics have been proposed to explain tongue protrusion in fire fatalities, among which the heat-induced shrinkage of cervical tissues, the heat-related vapor pressure, (10) focal hemorrhage and interstitial edema of the lingual tissues, (8) or the rigor of the genioglossus muscle caused by the high temperature. (11)

Some authors [Ishikawa et al 2018, Hashimoto et al 2003 and Quan et al 2003] focused their attention on the intramuscolar bleeding at the tongue base of charred cadavers [ImBT]: the proposed mechanic is linked to the cervical compression caused by an incomplete occlusion of the carotids, cranial venous stasis, spasm of the lingual muscles and hypertensive agony that would cause the intramuscolar bleeding of the tongue, similarly to what happens in some asphyctic deaths (e.g., incomplete, manual and ligature strangulation). Hashimoto and Ishikawa reported intramuscolar bleeding of the tongue in vital fire cases with low levels of COHb and severe charring of the body. In cases with insufficient blood level of COHb the proposed cause of death was the extensive carbonization of the cervical tissues that dramatically harden and compress the neck quite similarly to what happens in the abovementioned asphyctic deaths (e.g., strangulation). This could explain the occurrence of the intramuscolar bleeding reported in some vital carbonization cases. (12-14)

Because of the retrospective nature of the present study, the report is limited to 10 cases of tongue protrusion. Despite the small number of our sample, the occurrence of tongue protrusion was observed in all the cases of vital burning and in two of three cases of post-mortem fire. Unfortunately, in some of our cases the position of the tongue was not reported by the forensic pathologist in charge of the autopsy and the involvement of a forensic odontologist is limited to very few cases. A collaboration between the forensic pathologist and an odontologist would have perhaps resulted in a most appropriate attention to the mouth not only for identification issues (15, 16) but also for the possible contribution that the oral findings can give to the ascertainment of the cause of the death.

In the two cases of non-vital fire, the levels of COHb (less than 2%) and HCN were negative, no soot deposits were found and the presence of aortic and skull lesions, led to conclude for a death immediately following the helicopter crash. The carbonization of two bodies was extensive, the facial and neck tissue were severely destroyed by the fire, the tongue hemorrhage was not investigated during autopsy. Anyway, we can suppose that it would be likely absent, since the tongue bleeding requires an hypertensive agony and a vital burning that were excluded in the described cases. Among the different mechanic described in the literature as a cause of tongue protrusion in the perimortem period, mostly related to asphyctic deaths or vital burning, only the heat-induced retraction of the cervical tissues and the lowering of the mandible, seem to be considered in these two non-vital burning cases. Nikolic, in two post-mortem burning cases, described (11) a heat rigor in the cervical region as it occurs in the rest of the body due to the shortening of muscles and tendons, that causes relevant modifications of the position of the body (e.g., pugilistic position). The protrusion of the tongue is considered as a sort of lingual rigor due to the heat that causes a shortening of the genioglossus which, in a condition similar to a physiological activation, produce the thrust of the tongue out of the mouth.

CONCLUSION

A tongue protrusion is observed and reported in different types of death. Generally speaking, the position and modifications (especially bleeding) of the tongue are deeply investigated in asphyctic deaths (hanging, strangulation, etc), whilst these conditions are not so considered in fire casualties.

A long discussion stands in the literature between authors that believe that the protrusion of the tongue can be considered an useful sign of vitality during a fire and those who criticized this assumption.

Our study is based on a limited number of cases, but reveals the occurrence of a protruded tongue in all the cases of vital fire, but also in two thirds of non vital fire, emerging as an aspecific sign possibly correlated with exposition to high heat regardless of its ante or post-mortem occurance. The mechanics of the lingual protrusion in vital and non-vital burning is still a matter of discussion.

In cases of tongue protrusion in vital burning with lower COH levels similar mechanisms as in some types of asphyctic deaths are hypothesized to occur. In cases of non vital tongue protrusion a heat induced rigor of the genioglossus could explain the phenomenon. Further research on fire fatalities is required to analyze the tongue bleeding as a possible parameter to discriminate the vital by the non-vital tongue protrusion (12). Moreover, the mechanism at the origin of vital and non-vital tongue protrusion, the different position of the tongue (protruded from an open mouth, protruded and clenched between the dental arches, etc.) in different death circumstances, should be furtherly investigated with a meaningful collaboration between forensic pathologists and odontologists for a complete registration and interpretation of all the mouth originated evidence.