Sub-occipital ligature knot in a case of long drop suicidal hanging with rare autopsy finding of cervical spine fracture

Hanging is a form of death due to constriction of the neck when the force applied is derived from the gravitational drag of the victim’s body weight (DiMaio and DiMaio 2001; http://ncrb.nic.in/StatPublications/CII/CII2015/FILES/Statistics-2015.rev11.pdf). Among all the modes, hanging is the most common method of committing suicide in India according to recent data published by national crime records bureau, government of India (Sauko and Knight 2004).

In most of cases of suicidal hanging, cause of death is due to compression of vasculature and airway. Injury to upper cervical spine, usually at the level of C1-C2 and C2-C3 are mostly seen in judicial type of hanging, wherein the body falls from a sufficient distance before suspension (Dolinak and Matshes 2005; Hejna and Bohnert 2013). Hangman’s fracture as described by Wood Jones in 1913 involves fracture-dislocation of the 2nd cervical vertebra as a result of hyperextension and distraction of the neck (Wood-Jones 1913). If the length of drop is several meters, more profound injuries like decapitation (complete/incomplete) can occur (Rothschild and Schneider 1999). Hence, in judicial hanging drop length is calculated according to the height and weight of the individual to prevent decapitation.

Body weight, falling distance and nature of ligature material (elastic/inelastic) are the most important factors in the patho-mechanism of decapitation in long drop suspension (Byard and Gilbert 2017). When a moving body falls with noose around neck, it causes injuries to cervical structures through additional axial traction (deceleration force) and radial shearing forces of the tightening noose. Hence, in hanging cases with long-drop, the structures of the neck are injured by strain caused by increased gravitational drag produced by the body’s weight.

Herewith we are discussing a case of long drop suicidal hanging by using nylon rope as ligature material with sub-occipital position of knot and atypical autopsy findings of fracture-dislocation of upper cervical vertebra as position of the knot was unfavorable to cause such injuries.

Suicide by long drop hanging is a rare occurrence. These are usually ‘short-drops,’ and the total distance of the drop is less than 0.6–0.9 m. It is uncommon for suicidal hanging to involve a ‘long-drop’ in which the descent is between 4.3 and 5.2 m (Hellier and Connolly 2009).

A fall with a noose around the neck is associated with frequent injuries involving local structures as a result of axial traction and radial shearing forces. Victims although suffer a wide range of soft tissue injuries, fracture of the cervical spine along with spinal cord injuries are unusual in routine hanging. Exact incidence of cervical bony injury following suicidal hanging is not known, and has been observed different in different surveys. But when they occur, they tend to be described with reference to judicial hanging in which the body falls some distance before suspension (Dolinak and Matshes 2005). Long drop suspension, most typified by judicial execution is meant to result in fracture of C2 and C3 rather than obstruction of vasculature and airway (Thierauf and Pollak 2008). Typical “Hangman’s fracture” i.e. bilateral fracture of C2 with anterior sublaxation or dislocation of the body due to hyperextension of the neck can be seen in such long drops only (Hellier and Connolly 2009). Fractures may also occur between cervical vertebrae 1–2 or 3–4 (Toro et al 2008; Dedouit et al. 2007). Although, hyperextension has been described by majority of authors as the most common neck movement for causing fracture-dislocation, ante-flexion was also found by few (Zhu et al. 2000). Nikolic & Zivkovic reported cervical spine injury in a cases of hanging without long-drop pattern with a frequency 3.27% (Nikolic and Zivkovic 2014). But, in his series all the victims were old aged with severe osteoporotic changes in bones.

If the drop is sufficiently high, it may result in even more profound injuries such as decapitation. When a narrow wire is used, it may lacerate the soft tissue of neck even without a long drop (cheese cutter method). Occurrence of complete or incomplete decapitation can increase by the increasing energy stored as potential energy at the starting position and the characteristics of the rope extended by the hanging body (Toro et al 2008). Such energy can be stored by changing the position in the gravitational field, by changing the shape of the hanging rope and by changing the motion of the hanging body. In a biomechanical experiment, it was found that traction-forces of about 12,000 Newton lead to complete decapitation irrespectively of the diameter of the used halter (Rabl et al. 1995).

In the present case, the deceased felt down from a distance of 6.3 m before suspension and constriction by the rope. Usually, in such long drops, there is every chance of partial or complete decapitation due to traction force. However, there was laceration of skin over the antero-lateral aspect of the neck along with transection of larynx. This rare occurrence in such long drop can be described by the weight of the individual and nature (thick and elastic) of the ligature material. The deceased was an average built person with body weight 62 kg, which was insufficient to cause enough gravitational drag, thus preventing decapitation even after sufficient traction.

Fracture and dislocation of cervical vertebra C2 over C3 was noted in this case. Fracture of cervical vertebra in hanging occurs due to sudden movement of the neck, mostly by hyperextension. Such cases can be explained with respect to the position of knot, along with the drop height. To cause typical Hangman’s fracture, ideal position is either sub-mental or sub-aural. However, in our case, the position of the knot was in sub-occipital area and in this scenario cervical spine fracture is unlikely as it causes mostly ante-flexion of neck. Hence, this atypical presentation can be correlated with extreme height of long drop along with sudden drag irrespective of position of knot. Perhaps, the deceased jumped from the branch of the tree after tightening the rope, which is sufficiently high up causing sudden twist of the neck before suspension along with gravitational drag due to positional effect (Fig. 5). This movement at the time of suspension may be responsible for the fracture & dislocation.

Fracture of cervical spine in long drop suicidal hanging with sub-mental or sub-aural position of ligature knot is scientifically proven autopsy findings. However, in our case of long drop hanging, we found fracture of cervical spine when ligature knot was in sub-occipital position as a rare autopsy findings. We also noticed deep laceration of skin and transection of larynx as extremely rare finding caused by flexible and blunt nylon rope used as ligature. Hence, further study is required regarding exact patho-mechanism of such incidences to peer deep into such rare occurrences.