“Every man has leaned upon the past. Every liberty we enjoy has been brought at an incredible cost. There is not a privilege nor an opportunity that is not the product of other men’s labours. We drink every day from the wells we have not dug; we live by liberties we have not won; we are protected by institutions we have not set up. No man lives by himself alone. All the past is invested in the lives of others.” Dr. Thomas Gibbs NEUROVASCULAR LESIONS AND MECHANISMS IN SUICIDAL HANGING: AN ANATOMICAL, PHYSIOLOGICAL AND PATHOLOGICAL STUDY ‘ A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy in Medicine’ Jacob Joseph Moar Johannesburg, June 2012 DEDICATION To my supervisor Professor J.C. Allan without whose immense support and encouragement this thesis would not have been possible. i ABSTRACT Background and Purposes Suicide by hanging is a relatively common occurrence. The actual cause of death in suicidal hanging is, however, controversial, having been attributed variously to asphyxia, carotid artery compression and vagal nerve stimulation. The aim of this Ph.D thesis was to determine the possible neurovascular cause of death in suicides by hanging by careful study of the anatomy and physiology of the neck region in relation to the ensuing pathology. The study was, therefore, approached from an anatomical, physiological, histological and pathological pespective. It therefore comprised a detailed exploration of the anatomy and physiology of the neck structures to match these with the underlying traumatised neurovascular structures, the latter trauma being brought about by the suicidal hanging process. Methods The methods used in the study included an investigation of the ligature and position of the ligature in relation to the level of the neck and the physical effects of the ligature on the skin and underlying anatomical structures. A careful and detailed dissection of the neck was undertaken and samples of the vessels and nerves were processed for histological study. Fifty consecutive cases of suicidal hanging and five “non-hanging” cases which served as controls were used in the study. In addition, ten cases of suicidal hanging not included in the study were subjected to occlusion ii studies by means of probe exploration. This technique and procedure was not carried out or applied to the cases included in the study for fear that the probe itself might produce artefactual damage to the delicate endothelium lining the inner layer of the vessel wall. The study was classified into various components such as: 1. Examination of the type and structure of the ligature material; 2. The position of the ligature on the neck, i.e. whether involving upper, middle, or lower third of neck and to correlate this position with the underlying anatomical structures subjected to the accompanying tensile, compressive and haemodynamic forces; 3. The physical effects of the ligature upon the skin and the underlying deeper neurovascular structures of the neck; 4. Meticulous “bloodless” dissection of the neck structures to corroborate any pathology noted with the above three criteria. Currently, all putative causes of death remain speculative; 5. Particular attention was paid to those structures most vulnerable to the compressive forces, tensile forces and haemodynamic forces operative in hanging. These comprise the neurovascular structures contained within the fibrous carotid sheath and the phrenic nerves in the neck, in particular with regard to the anatomical relationship of these structures to the positioning of the ligature. As far as analysing the forces involved, the engineering principles pertaining to these were interpreted in consultation with the Faculty of Engineering at the University of the Witwatersrand. iii Results The main findings of the study showed damage to vascular, neural (including phrenic nerve), carotid bodies and accessory glomal bodies. The vascular findings emerged following an examination of the total number of arteries in the study, namely, 300, the figure derived as follows: six arteries in each of the fifty hanging subjects, viz., the left common carotid artery, the right common carotid artery, the left internal carotid artery, the right internal carotid artery, the left external carotid artery and the right external carotid artery (6 x 50 = 300). The damage shown was particularly the case with regard to the finding of tears in the various layers of the vessel wall. These extended from the intima through to the adventitia or outermost layer of the vessel wall and these were further subdivided into being either single or multiple. The tears found ranged from those involving the intima alone (single tears being found in 17 (5.6%) of the 300 arteries examined and multiple tears in 37 (12.3%) of the 300 arteries examined., the intima extending to the internal elastic lamina (single tears being found in 20 (6.6%) of the 300 arteries examined and multiple tears in 8 (2.6%) of the 300 arteries examined), tears involving the intima and extending through to involve the media, i.e. intimo- medial tears and whether these latter tears involved the inner-, middle-, or outer-thirds of the media (single or multiple). Single intimo-medial tears extending through the intima to involve the inner-third of the media comprised 6 (2.0%) of the arteries examined, those extending from the intima to involve the middle-third of the media comprised 3 (1.0%) of the 300 arteries examined and single intimo-medial tears extending through the intima to involve the outer- iv third of the media similarly comprised 3 (1%) of the arteries examined. Multiple intimo-medial tears extending through from intima to inner-, middle-, and outer- thirds of the media respectively, comprised 3 (1.0%), 5 (1.6%) and 1 (0.3%) of the arteries examined. Single tears involving the inner-third of the media alone comrised 6 (2.0%) of the 300 arteries examined, single tears involving the middle-third of the media comprised 9 (3.0%) of the arteries examined and single tears involving the outer-third of the media alone comprised 8 (2.6%) of the arteries examined. Multiple tears involving the inner-, middle and outer-thirds of the media respectively comprised 6 (2.0%), 13 (4.3%) and 16 (5.3%) of the arteries examined. Single tears involving both adventitia and media, i.e. adventitio-medial tears extending through the inner-, middle-, or outer-thirds of the media to involve the adventitia comprised 1 (0.3%), 2 (0.6%) and 6 (2.0%) respectively of the 300 arteries examined. Multiple adventitio-medial tears of the inner-, middle-, and outer-thirds of the media, respectively, comprised 0 (0.0%), 3 (1.0%) and 2 (0.6%) of the 300 arteries examined. Single tears of the adventitia alone comprised 21 (7.0%) of the arteries examined while multiple tears comprised 7 (2.3%). Complete circumferential transverse rupture of the vessel wall was found in 3 (1.0%) of the arteries examined while adventitial haemorrhage was found in 103 (34.3%) of the 300 arteries examined. The vascular findings were represented numerically in tabular form in the 50 hanging subjects in Table III and were further analysed and compared with regard to either unilateral or bilateral vessel involvement in the fifty (50) suicidal v hanging subjects and the findings represented in Tables IIIa (unilateral involvement) and IIIb (bilateral involvement). Additional vascular findings comprised endothelial elevation/avulsion, internal elastic lamina dehiscence, subendothelial clefts, multiple medial fenestrations, adventitio-medial separation, vascular congestion and a vascular plane of cleavage. These were similarly represented in Table IV and analysed with regard to unilateral or bilateral involvement in Tables IVa and IVb. Endothelial elevation/avulsion was found in 295 (98.3%) of the 300 arteries examined, internal elastic lamina dehiscence in 290 (96.6%) of the arteries examined, subendothelial clefts in 289 (96.3%) of the arteries examined, multiple medial fenestrations in 17 (5.6%) of the arteries examined, adventitio- medial separation in 273 (91.0%) of the arteries examined, vascular congestion in 224 (74.6%) of the arteries examined and a vascular plane of cleavage in 98 (32.6%) of the arteries examined. These findings, unexpected, showed the extreme fragility and vulnerability of the intima and adventitia to the compressive and tensile forces acting on the vessel wall during hanging, being explicable not only on the basis of the various complex forces interacting simultaneously during hanging but on the magnitude of forces applied. A mathematical analysis, found at the end of the Discussion chapter, conducted in order to estimate the minimum peak pressure applied and exerted on the vessel wall during hanging, in collaboration with the School of Mechanical, Industrial and Aeronautical Engineering at the University of the Witwatersrand, confirmed the magnitude of these forces. The neural findings (Table V) were divided into neural congestion, neural haemorrhage, neural internal dehiscence, neural tearing and perineural vi separation and these were similarly analysed with regard to either unilateral or bilateral involvement in the fifty hanging subjects (Tables Va and Vb). Neural congestion was found in association with 20 (6.6%) of the 300 arteries examined, neural haemorrhage in14 (4.6%), neural internal dehiscence in 54 (18.0%), neural tearing in 35 (11.6%) and perineural separation in 112 (37.3%). Neural ganglionic findings were similarly divided into ganglionic congestion, ganglionic haemorrhage, ganglionic internal dehiscence and ganglionic tearing. Ganglionic congestion, in association with the 300 arteries examined, was found in 20 (6.6%), ganglionic haemorrhage in 8 (2.6%), ganglionic internal dehiscence in 15 (5.0%) and ganglionic tearing in 6 (2.0%). The findings in the carotid bodies were divided into carotid body congestion, carotid body haemorrhage, carotid body internal dehiscence and carotid body tearing.