INTRACRANIAL VASCULAR LESIONS
Several intra-cranial lesions cause death. However, most of these lesions tend to cause significant symptoms that would lead to diagnosis of the condition. However, a few lesions go undetected, asymptomatic until a fatal incident reveals the condition on autopsy.
Ruptured berry aneurysm
Sudden collapse and death of young men and women frequently demonstrate subarachnoid hemorrhage caused by rupture of a congenital aneurysm of arteries of circle of Willis itself or in its tributaries. While these aneurysms are not present at birth, the weakness in the media of the vessel wall is present at birth, leading to development of the aneurysm over time.
The aneurysms range from a few millimeters to several centimeters in diameter, may be single or multiple, located in one or more arteries. The aneurysms may be asymptomatic or may cause severe headache, neck stiffness, and unconsciousness and sometimes even paralysis or other neurological symptoms.
Rupture of the aneurysm can cause extravasation of blood into the sub-arachnoid space, primarily over the base of the cerebrum but may also be seen over the cerebellum. If the aneurysm is embedded in the brain, it may cause hemorrhage into the brain tissue itself.
The mechanism for death is thought to be either due to vascular spasms causing hypoxia of the vital centers or direct effect on the centers by the blood itself.
The finding of a ruptured aneurysm in a case of documented assault, especially without any significant head injury, complicates the investigation. In such cases, the causal relation of blood pressure, caused by increased adrenergic release due to the ‘stress’ of the altercation, is still controversial and requires further research. Alcohol intoxication is frequently associated in such cases and is another risk factor for the rupture.
Demonstration of these aneurysms or ruptures of intracranial vessels requires tedious dissection, preferably under operating microscope, and should be examined thoroughly to rule out spontaneous rupture of pre-existing aneurysms caused by trauma to the head.
Cerebral hemorrhage, thrombosis and infarction
Cerebrovascular accidents are common in the elderly, especially with significant hypertension, and along with thrombosis and infarction, is the commonest cause of neurological signs of ‘stroke’.
Charcot-Bouchard aneurysm is a spontaneous intracerebral hemorrhage due to rupture of micro-aneurysm of lenticulo-striate artery. Hemorrhage are commonly seen in the external capsule/basal ganglia. The sudden expansion of a hematoma compresses the internal capsule and may lead to hemiplegia. Death in such circumstances is not usually sudden. The sudden hemorrhage may cause direct action on the vital centers or may cause pressure effects leading to death due to cardiac failure.
The major cause of sudden death affecting the respiratory system is also vascular. Pulmonary thromboembolism is very common and the most clinically under-diagnosed cause of death. In almost every case, the source of the emboli is in the deep veins of the lower limbs. Tissue trauma, especially associated with immobility or bed rest, is a very common predisposing factor in the development of deep vein thrombosis.
Most thromboses remain asymptomatic and rarely cause complication, but a proportion undergo embolism and migrate to the lungs where they block pulmonary arteries of varying sizes. Large saddle thromboembolism can occlude the origin, resulting in acute right-heart failure, whereas smaller thromboembolisms occlude smaller pulmonary blood vessels where they cause dissociation of gaseous exchange and lead to myocardial ischemia and death.
Significant predisposing factors include immobility following surgery or trauma, use of oral contraceptive, smoking, and history of metastatic cancer or clotting abnormality. However, some cases may have no significant clinical history or symptomatology and occurs unexpectedly in normal, ambulant individuals.
Other rarer causes of sudden respiratory death include massive hemoptysis from tuberculous cavitation or tumor. Fulminating infections, especially virulent forms of influenza tend to cause rapid death, though not fast enough to be classified as sudden.
Gastrointestinal hemorrhage is the main cause of sudden death in due to gastrointestinal condition. While generally treatable if diagnosed early, massive hemorrhages have been reported in gastric or duodenal peptic ulcer resulting in sudden death.
Mesenteric thrombosis and embolism, usually related to aortic or more generalized atherosclerosis, may result in infarction of the gut, leading to rapid deterioration but not sudden death, even if undiagnosed. Intestinal infarction due to other causes like strangulated hernia, or torsion due to diffuse adhesions can also prove rapidly fatal. Peritonitis, diverticulitis or perforation, can be rapidly fatal in our context with poor access to quality medical care. These conditions tend to present as unexplained deaths due to refusal to seek timely medical advice.
Septic abortion remains one of the leading causes for sudden unexplained deaths in developing countries. Ruptured ectopic pregnancy, commonly in fallopian tubes, is another obstetric emergency presenting as sudden death due to lack of access to proper antenatal checks and is more common in the first trimester. Death occurs due to massive intraperitoneal bleeding.
Maternal and obstetric deaths are dealt with in detail on the chapter on maternal deaths. Gynecological deaths are less frequent and are usually associated with advanced carcinomas causing metastasis or due to aggressive tumors causing rupture of pelvic blood vessels leading to massive hemorrhage.
However, it should always be remembered that unexplained deaths in females of childbearing age should be suspected to be due to obstetric complications until findings prove otherwise.
In addition, any unexplained death in women should be examined methodically to rule out any sexual violence or assault. Rapid deaths are also seen in deaths associated with sexual assault; however, such cases are traumatic in origin and are not classified under sudden death. They are discussed in the chapter on examination in deaths due to sexual violence.
DEATHS FROM EPILEPSY
Repeated seizures are associated with recurrent episodes of hypoxia and cerebral injury, leading to an increased risk of mortality. Death may be caused by a epilepsy causing a specific sequence of events leading to death, for example a seizure while swimming causing death from drowning or seizure causing fall resulting in death from blunt trauma to head.
Sudden unexpected deaths in epileptics are classified as Sudden Unexpected Deaths in Epilepsy (SUDEP), and has been defined as ‘sudden unexpected, witnessed or unwitnessed, non-traumatic and non-drowning death in epilepsy, with or without evidence of a seizure, and excluding documented status epilepticus, where post-mortem examination does not reveal a toxicological or anatomic cause of death’. The mechanism of death in such cases is unknown, but has been proposed to be due to seizure-induced arrhythmia, respiratory center inhibition or a complication of treatment.
Post-mortem findings are nonspecific and include pulmonary edema and congestion. The presence of injury to the tongue does not necessarily confirm seizure at the time of death. Detailed examination of the brain is essential to exclude underlying lesion causing the seizure, such as traumatic injury or arteriovenous malformation.