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FMT Chapter 6 - Death and Its Causes: Complete Exam Notes
(Source: The Essentials of Forensic Medicine and Toxicology, 36th Edition, 2026 - KS Narayan Reddy)
1. DEFINITIONS AND TERMINOLOGY
| Term | Definition |
|---|
| Thanatology | (Thanatos = death) - study of death in all its aspects, including changes that occur with and after death |
| Death (Legal - BNS) | Section 2(6) BNS Act 45 of 2023 (old S.46 IPC): "death of a human being unless contrary appears from context" |
| Death (Registration Act) | Registration of Births and Deaths Act, 1969 S.2(b): "Permanent disappearance of all evidence of life at any time after live birth" |
| Forensic Taphonomy | Interdisciplinary study of postmortem biological changes of human remains in dispositional context |
Exam Tip: "Death is not an event; it is a process."
2. TYPES OF DEATH (FM2.3)
A) SOMATIC DEATH (Clinical / Systemic Death)
- Definition: Complete and irreversible stoppage of Circulation + Respiration + Brain function
- Also called: Clinical death / Systemic death
- Bishop's Triad of Life (Nicolas Bishop, 1638-1686): Circulation + Respiration + Brain function
- Current concept: Somatic death = death of the brainstem
- As long as oxygenated blood reaches the brainstem = life exists
- A person who cannot survive withdrawal of artificial maintenance = dead
Bichat's Modes of Death (Xavier Bichat, 1771-1802):
| Mode | Mechanism |
|---|
| Coma | Stoppage of brain function |
| Asphyxia | Stoppage of respiration |
| Syncope | Stoppage of circulation |
Exam Tip: Bishop's triad = 3 components of life. Bichat's 3 modes = 3 ways life stops. Both describe the same triad from different angles.
B) MOLECULAR DEATH (Cellular Death)
- Definition: Death of cells and tissues individually, after somatic death
- Occurs 1-2 hours after stoppage of vital functions
- Occurs piecemeal (not all at once)
- Individual cells survive on residual oxygen - duration depends on metabolic activity
Order of tissue death (fastest to slowest):
| Tissue | Dies After Death |
|---|
| Cerebral cortex (vital centers of brain) | ~5 minutes |
| Basal ganglia | ~6-7 minutes |
| Vagal center | ~9-10 minutes |
| Skeletal muscle | 1-2 hours |
Signs of Molecular Death (Muscle Excitability Tests):
| Test | Description | Duration After Death |
|---|
| Zasko's Phenomenon (Tendon Reaction) | Strike lower 1/3 of quadriceps femoris (~10 cm above patella) → upward movement of patella | Up to 1-2 hours |
| Idiomuscular Contraction (Bulge) | Strike biceps brachii with back of knife → local muscular bulge | Phase 1: immediate; Phase 2: 4-5 hours; Phase 3: 8-12 hours (lasts up to 24 hours) |
| Electrical Excitability | Electrical excitability of facial muscles | Few hours after death |
Exam Tip: Molecular death = cellular death = death of individual tissues. Brain dies first, muscles last.
C) BRAIN DEATH
Types:
- Cortical Death - Only cortex is damaged; brainstem intact → "Persistent Vegetative State" (PVS). Patient breathes spontaneously, stable circulation, sleep-wake cycles present but no awareness.
- Brainstem Death - Complete irreversible loss of brainstem function → legally and medically = death
Harvard Criteria for Brain Death (1968):
- Unreceptivity and unresponsivity (deep coma)
- No spontaneous movements or breathing
- No reflexes
- Flat EEG (isoelectric) - confirmatory
Preconditions Before Testing:
- Patient must be deeply comatose
- Patient must be on a ventilator
- Cause of coma must be known
- Core temperature must be >35°C
- Rule out: drugs/overdose, hypothermia (<35°C), metabolic/endocrine disturbance
Personnel for Brainstem Death Tests:
- Must be performed by two medical practitioners
- Both must be experts; transplant surgeons cannot perform tests
- At least one must be of consultant status (junior doctors not permitted)
- Each doctor must perform the tests twice
Brainstem Death Tests (cranial nerve function):
- Pupillary response to light
- Corneal reflex
- Vestibulo-ocular reflex
- Gag or cough reflex
- Grimacing to pain
Schools of Diagnosing Death:
- French and English schools (similar to Harvard)
- Austro-German school = Harvard criteria + bilateral serial angiography of internal carotid and vertebral artery; negative angiogram for >15 min = proves death
D) SUSPENDED ANIMATION
- Definition: Vital functions are at such a low pitch that they cannot be detected by routine clinical examination - mimics death but is reversible
- Death has NOT occurred; resuscitation is possible
Causes of Suspended Animation:
- Hypothermia (most common - MCQ answer)
- Drowning
- Electrocution
- Strangulation/Hanging
- Cholera (severe dehydration)
- Drug overdose
Exam Tip (MCQ): Suspended animation = temporary cessation of vital functions. Most common cause = Hypothermia. It can mimic death. Recovery is possible. NOT always reversible (false).
3. CAUSE OF DEATH (FM2.6)
Definition: The disease or injury responsible for starting the sequence of events leading to death.
3 Components of Cause of Death:
| Component | Definition | Example |
|---|
| Immediate Cause | Injury/disease present at time of terminal event | Septicemia, bronchopneumonia, peritonitis |
| Basic (Underlying) Cause | Pathological process responsible for/leading to the terminal event | Gunshot wound of abdomen → peritonitis |
| Contributory Cause | Pathological process involved in/complicating but NOT causing the terminal event | Pre-existing diabetes |
Manner of Death:
- Natural - death caused entirely by disease (no trauma/poison)
- Unnatural/Violent - death by injury, or natural disease hastened by injury
- Sub-types: Suicidal, Homicidal, Accidental, Undetermined
4. MEDICAL CERTIFICATE OF CAUSE OF DEATH (MCCD) - ICD-11 Format
(As per WHO ICD-11 guidelines)
Part I: Disease/condition directly leading to death (causal sequence - top to bottom):
- Line (a) = Immediate cause (e.g., Septicemia)
- Line (b) = Intermediate cause (e.g., Extensive burns)
- Line (c) = Underlying cause (e.g., Assault by burning - dowry related) → this gets the ICD-11 code
Part II: Other significant conditions contributing to death but NOT part of the causal chain (e.g., hypertension, diabetes)
ICD-11 Example:
- Dowry assault death: ICD-11 code = PK80.1 (Assault by burning)
Exam Tip: The underlying cause in Part I is what gets coded in ICD-11 - it is the root event that started everything.
5. MODES OF DEATH - BICHAT'S TRIAD IN DETAIL
A) SYNCOPE (Stoppage of Circulation)
- Sudden failure of cardiac action with stoppage of circulation
- Heart stops first → respiration stops within 20 minutes
B) COMA (Stoppage of Brain Function)
- Unarousable unconsciousness; no psychologically understandable response to external stimuli or inner need
- Involves central portion of brainstem
- Coma is a clinical symptom, NOT a cause of death
Causes of Coma:
- Brain compression (blood/pus/tumor)
- Drugs: opium, hypnotics, cocaine, alcohol, cyanide, CO
- Metabolic disorders: uremia, hepatic failure, hypoglycemia, electrolyte imbalance
- Infections: meningitis, encephalitis
C) ASPHYXIA (Stoppage of Respiration)
- Interference with respiration or lack of O₂ causing organs/tissues to be deprived of oxygen (+ failure to eliminate CO₂)
- "Asphyxia indicates a mode of dying, not a cause of death"
Brain uses 20% of total body oxygen despite being only 1.4% of body weight.
Thumb Rule:
- Breathing stops within 20 seconds of cardiac arrest
- Heart stops within 20 minutes of breathing stoppage
Cortical damage timing in total ischemia:
- Cerebral cortex function stops: 8-15 seconds
- Brainstem ganglia: 25-30 seconds
- Irreparable cortex damage: ~3 minutes
Types of Anoxia (4 types):
| Type | Mechanism |
|---|
| Anoxic anoxia | Lack of O₂ in inspired air / mechanical obstruction - known as asphyxia |
| Anemic anoxia | Reduced O₂-carrying capacity (e.g., CO poisoning, hemorrhage) |
| Stagnant anoxia | Sluggish/stopped circulation (e.g., cardiac failure) |
| Histotoxic anoxia | Tissues unable to utilize O₂ (e.g., cyanide poisoning) |
Signs/Features of Asphyxia:
- Tardieu spots = petechial hemorrhages on visceral surface of pleura (classic)
- Petechial hemorrhages on brain (white matter)
- Cyanosis
- Congestion of internal organs
- Frothy mucus in airways
- Pulmonary edema
6. SUDDEN DEATH (FM2.5)
Definition (WHO): Person not known to be suffering from any dangerous disease, injury, or poisoning found dead or dies within 24 hours after onset of terminal illness.
- Some authors define it as death within 1 hour of symptom onset
- Incidence: approximately 10% of all deaths
- Emphasis on unexpected character rather than suddenness
System-wise Causes of Sudden Death (Table 6.1):
| System | % | Key Causes |
|---|
| Cardiovascular | 45-50% (Most common) | Coronary atherosclerosis ± thrombosis, MI, aortic rupture, pulmonary embolism, cardiomyopathy, arrhythmia, conduction system lesions |
| Respiratory | ~15% | Acute laryngeal edema (anaphylaxis), status asthmaticus, pulmonary embolism, spontaneous pneumothorax |
| CNS | ~15% | Subarachnoid hemorrhage, cerebral hemorrhage, epilepsy, meningitis |
| GIT/Abdominal | ~5-10% | Ruptured ectopic pregnancy, GI hemorrhage, ruptured aortic aneurysm |
| Others | Variable | Anaphylaxis, electrolyte imbalance, hypoglycemia |
Exam Tip (MCQ): Most common cause of sudden death = Cardiovascular (45-50%). Most common specific cause = Coronary atherosclerosis.
7. OBSCURE AUTOPSY
- Autopsy where no definite anatomical cause of death is found
- "The doctor should admit inability to give a positive opinion"
- Common obscure deaths: hypoglycemia, hyperkalemia, cardiac arrhythmias, epilepsy, vagal inhibition, snake bites
- When no cause found + natural circumstances: certify as "undetermined natural circumstances"
- When circumstances equivocal: certify cause and manner as "undetermined"
- Old age with generalized senile atrophy: certify as "myocardial degeneration due to senility"
QUICK MEMORY CHART FOR EXAM
| Topic | Key Fact |
|---|
| Thanatology | Study of death in all aspects |
| Somatic death = | Irreversible stoppage of Circulation + Respiration + Brain (Bishop's triad) |
| Current concept of somatic death | Death of brainstem |
| Bichat's modes | Coma, Asphyxia, Syncope |
| Molecular death timing | 1-2 hours after somatic death |
| Brain vital centers die | ~5 minutes after somatic death |
| Muscles die | 1-2 hours after somatic death |
| Zasko's phenomenon | Strike quadriceps → patella moves; up to 1-2 hours |
| Harvard criteria | 1968; assesses brainstem; flat EEG confirmatory |
| Brain death tests by | 2 doctors (NOT transplant surgeons); consultant status |
| Suspended animation cause | Hypothermia (most common) |
| Asphyxia = | Mode of dying, NOT a cause of death |
| Tardieu spots | Petechiae on visceral surface of pleura |
| Sudden death (WHO) | <24 hours after onset; 10% of all deaths |
| Most common cause sudden death | Cardiovascular (45-50%) |
| Coma | Symptom, NOT cause of death |
| Breathing stops after cardiac arrest | 20 seconds |
| Heart stops after breathing stops | 20 minutes |
Source: The Essentials of Forensic Medicine and Toxicology, 36th Edition (2026) - Chapter 6, FM2.1, FM2.3, FM2.5, FM2.6, FM2.7