GROUP - A (LAQ - 15 Marks)

Q1. Methanol (Methyl Alcohol) Poisoning

i) Causative Agent and Mechanism of Action (1+3 = 4 marks)

Methanol → Formaldehyde → Formic Acid → CO₂ + H₂O
          (alcohol dehydrogenase)  (aldehyde dehydrogenase)

1. Formic Acid is the primary toxic metabolite. Its main mechanism of toxicity is binding to cytochrome c oxidase (Complex IV of the mitochondrial electron transport chain) and blockade of oxidative phosphorylation. This leads to:
   • Shift to anaerobic metabolism
   • Accumulation of lactic acid → high anion gap metabolic acidosis
   • Methanol metabolism also increases NADH/NAD+ ratio, which further converts pyruvate to lactate, worsening lactic acidosis
2. Effect of pH on formic acid toxicity: Acidemia increases toxicity as:
   • It favours the undissociated (lipid-soluble) form of formic acid, which crosses tissue barriers more easily
   • More formic acid enters brain and ocular tissues (retina and optic nerve), causing retinal toxicity and optic neuritis
   • Acidosis also prolongs elimination of formic acid via increased tubular reabsorption
3. Ocular toxicity: Formic acid directly damages the retinal ganglion cells and optic nerve, causing the characteristic visual symptoms - blurred vision, diminished vision, constricted visual fields, photophobia, nystagmus, and ultimately permanent blindness.
4. CNS depression: Acts similar to ethanol initially, causing CNS depression

ii) Stages of Ethyl Alcohol (Ethanol) Intoxication (4 marks)

• 80 mg% = Legal limit for driving in India (Motor Vehicles Act)
• 300 mg% = Coma threshold
• 500 mg% = Usually fatal
• 450-500 mg% = MLD (Minimum Lethal Dose)

iii) Korsakoff's Psychosis (2 marks)

• Anterograde amnesia - inability to form new memories (most prominent feature)
• Retrograde amnesia - loss of memories from the past
• Confabulation - fabrication of plausible but false memories to fill memory gaps (hallmark sign)
• Disorientation in time and place
• Relative preservation of other intellectual functions and consciousness

Q2. Opioid/Heroin Poisoning

a) Probable Diagnosis and Bedside Test (2 marks)

1. Coma / Unconsciousness
2. Bilateral pinpoint (miotic), non-reactive pupils
3. Respiratory depression (pulse rate 15/min here is likely respiratory rate - 15 breaths/min with severe depression; bradycardia also present)

• Administer 0.4-2 mg IV Naloxone (opioid antagonist)
• A positive response (reversal of coma, pupil dilation, improvement in respiration) within 1-2 minutes confirms opioid poisoning
• This is simultaneously diagnostic AND therapeutic

b) Mechanism of Action of Heroin/Opioids (3 marks)

1. Inhibition of adenylyl cyclase → decreased intracellular cAMP
2. Increased K+ conductance (hyperpolarization of neuronal membrane)
3. Decreased Ca²+ influx → reduced neurotransmitter release

• Respiratory centres (brainstem): Depression of the pre-Bötzinger complex → bradypnoea, apnoea, respiratory failure (primary cause of death)
• Midbrain (Edinger-Westphal nucleus): Stimulation → miosis (pinpoint pupils) - persists even in deep coma
• Vomiting centre: Initial stimulation (nausea/vomiting) then depression
• Cardiovascular: Hypotension, bradycardia via central and peripheral mechanisms
• CNS: Euphoria (mesolimbic pathway), then sedation, stupor, coma
• GI: Reduced motility (constipation), increased tone of sphincters (biliary spasm)
• Histamine release: Causes frothy secretions, bronchospasm, pruritus

c) Management (7 marks)

1. Airway: Position patient (lateral/recovery), clear airway of secretions and froth by suction; if GCS < 8, secure airway with endotracheal intubation
2. Breathing: Assisted ventilation - bag-mask ventilation or mechanical ventilation for respiratory failure; administer 100% oxygen
3. Circulation: IV access × 2 (large bore); fluid resuscitation for hypotension (Normal saline); vasopressors if refractory hypotension
4. IV fluids: Correct dehydration and hypotension

• Naloxone (Narcan) - pure opioid antagonist - is the drug of choice
• Dose: 0.4-2 mg IV (can also be given IM, intranasal, or via endotracheal tube)
• Onset of action: 1-2 minutes IV
• Can be repeated every 2-3 minutes up to a total dose of 10 mg
• Since heroin's duration of action exceeds naloxone's (half-life ~1 hour vs naloxone's 30-90 min), continuous IV infusion of naloxone may be needed (typically 2/3 of the initial effective dose per hour)
• Monitor for re-narcotization (relapse into coma) after naloxone wears off
• Naltrexone (long-acting oral opioid antagonist) can be used for maintenance after acute episode

• Gastric lavage if oral ingestion suspected and patient is intubated (within 1-2 hours of ingestion)
• Activated charcoal (1g/kg) if ingested orally and airway is protected
• Catheterisation of bladder (urinary retention)
• Treat pulmonary oedema (non-cardiogenic) with CPAP/mechanical ventilation and diuretics
• Skin care: Treat injection site abscesses; blood cultures for infective endocarditis (common in IV drug users)
• Antibiotics for sepsis/bacterial complications
• Monitor ECG (QT prolongation with methadone)
• Blood sugar check (hypoglycemia can mimic opioid coma)
• Observation for minimum 24 hours after naloxone therapy

• Drug rehabilitation and detoxification programme
• Methadone/buprenorphine maintenance therapy
• Counseling and psychosocial support
• Hepatitis B, C and HIV screening and management (due to IV drug use)

d) Samples at Autopsy with Preservatives (3 marks)

GROUP - B (SAQ - 10 Marks)

B1. Clinical Approach to Acute Alcohol Drunkenness

• Amount, type (country liquor/branded), time of last drink, duration of drinking
• Empty liquor bottles at scene; witness accounts
• Any co-ingested drugs (benzodiazepines, opioids - must be excluded)
• Past history of alcohol dependence, liver disease
• Any trauma (fall, head injury)

• Smell of alcohol on breath (fruity/ethanol odour)
• Flushing of face, conjunctival congestion
• Level of consciousness (GCS)
• Vital signs: BP, pulse, temperature, respiratory rate

• Romberg's test: Positive (unsteady with eyes closed) - ataxia
• Finger-nose test: Incoordination (cerebellar signs)
• Gait assessment: Ataxic, staggering gait
• Speech: Slurred (dysarthria)
• Pupils: Usually normal or slightly dilated; react to light (contrast with opioids - miosis; contrast with methanol - early normal then late changes)
• Deep tendon reflexes
• Nystagmus on lateral gaze

• Breathalyzer / Alcometer: Quick bedside estimation of BAC - most commonly used in traffic cases
• Romberg's test, Finger-nose test, Walking-the-line test - for clinical intoxication assessment
• Blood Alcohol Concentration (BAC): Gold standard (Widmark's formula, gas chromatography)
• Urine Alcohol Level
• Rule out head injury (CT head if indicated), hypoglycemia, drug overdose

1. Whether the person is under influence of alcohol (Yes/No)
2. The degree of intoxication (mild/moderate/severe)
3. Whether the person is fit to drive or participate in legal proceedings
4. Estimated BAC at the time of examination
5. Whether there are signs suggesting another cause (drug overdose, head injury, metabolic disorder)
6. Time of examination relative to alleged time of driving/event (for back-calculation using Widmark's formula)

B2. Acute and Chronic Ethyl Alcohol Poisoning + Management of Methanol Poisoning

Acute Ethyl Alcohol Poisoning (3 marks)

• Smell of alcohol on breath
• Euphoria, loss of inhibitions, talkativeness
• Flushing, vasodilation, warm skin
• Slurred speech, ataxia, diplopia
• Nausea, vomiting (risk of aspiration)
• In severe cases: stupor, coma, respiratory depression
• Hypoglycemia, hypothermia
• Death by: respiratory failure, aspiration pneumonia, cardiovascular collapse

Chronic Ethyl Alcohol Poisoning (3 marks)

• CNS: Peripheral neuropathy, cerebellar degeneration, Wernicke's encephalopathy, Korsakoff's psychosis, cerebral atrophy, dementia
• Liver: Alcoholic fatty liver → Alcoholic hepatitis → Cirrhosis → Hepatocellular carcinoma
• GI: Gastritis, peptic ulcer, pancreatitis (acute and chronic), malabsorption
• CVS: Alcoholic cardiomyopathy, arrhythmias (holiday heart syndrome - AF), hypertension
• Haematological: Megaloblastic anaemia (folate deficiency), thrombocytopenia
• Nutritional: Thiamine (B1) deficiency, pellagra (B3), folate deficiency
• Reproductive: Impotence, gynaecomastia, testicular atrophy; fetal alcohol syndrome in offspring
• Immune: Increased susceptibility to infections (TB, pneumonia)
• Psychological: Alcohol dependence syndrome, depression, personality changes, social deterioration

Management of Methanol Poisoning (4 marks)

1. ABC resuscitation - airway, breathing, circulation
2. IV access - rapid fluid resuscitation

• Gastric lavage (useful even after 2-4 hours due to slow gastric emptying with methanol)
• Activated charcoal is NOT effective for methanol

1. Ethanol (Ethyl alcohol) - First-line antidote where fomepizole is unavailable
   • Competes with methanol for alcohol dehydrogenase (250× greater affinity)
   • Loading dose: 0.6-0.8 g/kg IV (as 10% ethanol in 5% dextrose) or oral
   • Maintenance: Titrate to maintain blood ethanol of 100-150 mg/dL
   • Monitor for hypoglycemia and ethanol toxicity
2. Fomepizole (4-MP, 4-Methylpyrazole) - Preferred where available
   • Direct inhibitor of alcohol dehydrogenase
   • Dose: 15 mg/kg IV loading, then 10 mg/kg q12h × 4 doses, then 15 mg/kg q12h
   • Advantages: No CNS depression, easier to administer, no glucose monitoring needed

• IV Sodium bicarbonate for severe acidosis (pH < 7.1)
• This also decreases tissue entry of formic acid

• Indications: Methanol level > 25-50 mg/dL, severe HAGMA, visual impairment, renal failure
• Removes both methanol and formic acid
• Continue ethanol/fomepizole during dialysis (both are dialyzable)

• Folinic acid (leucovorin) or Folic acid 1 mg/kg (max 50 mg) IV q4h
• Enhances conversion of formic acid to CO₂ + H₂O via the folate pathway
• Theoretically hastens formic acid clearance

• Correct electrolytes, treat hypoglycemia
• Ophthalmological consultation for visual assessment
• High-dose corticosteroids may be used for optic neuritis

B3. Carbon Monoxide Poisoning - Closed Room Family Death

i) Causes of Death (1 mark)

• Asphyxia from oxygen depletion (O₂ consumed by fire, replaced by CO₂ and CO)
• Direct thermal injury / heat stroke (unlikely here as survival from fire is implied)
• The scenario is consistent with an accidental winter tragedy (common in India - using coal/wood fires in closed rooms for warmth)

ii) Post-Mortem Findings (4 marks)

• Cherry-red / bright pink discolouration of skin, lips, nail beds, and conjunctivae - pathognomonic; due to carboxyhemoglobin in cutaneous vessels
• However, cherry-red colour may be absent in dark-skinned individuals, severe anaemia, or if CO% is low
• May be cyanosed if O₂ depletion was prominent
• Bullous (blistering) skin lesions on pressure areas (elbows, knees, sacrum) - discrete, contain thick cellular fluid with inflammatory ring; pathognomonic of CO poisoning
• Face may be pink or livid

• Blood: Bright cherry-red, liquid (does not clot) - due to carboxyhemoglobin
• Muscles: Cherry-red colour
• Organs: Cherry-red or pink discolouration of all viscera - liver, kidney, brain
• Brain: Congestion, oedema; bilateral symmetrical necrosis of globus pallidus (characteristic delayed neuropathological finding); haemorrhagic infarction of basal ganglia in chronic survivors
• Lungs: Oedema, congestion; may show pulmonary haemorrhages
• Heart: Petechial haemorrhages on epicardium; areas of myocardial necrosis
• Retinal haemorrhages
• Stomach and bowel may show haemorrhagic erosions

• Spectroscopic examination of blood: Two absorption bands of COHb at 570 nm and 535 nm (unchanged after addition of reducing agents like ammonium sulphide, unlike oxyhaemoglobin)
• Gettler-Freimuth test (or Zsygmondy test)

iii) Diagnosis of Carbon Monoxide Poisoning (5 marks)

1. Carboxyhemoglobin (COHb) level by co-oximetry - gold standard; measured from venous/arterial blood; falsely elevated by SpO₂ pulse oximetry (cannot differentiate COHb from OxyHb)
2. Arterial Blood Gas: Metabolic acidosis, normal pO₂ (dissolved O₂ unaffected), low SaO₂ on co-oximetry
3. Spectroscopic examination of blood:
   • Two dark bands at 570 nm and 535 nm
   • Bands persist after addition of ammonium sulphide (unlike oxyhaemoglobin whose bands disappear)
   • Alkali (NaOH) test: COHb + NaOH remains cherry-red; oxyhaemoglobin turns brownish-green
   • Formaldehyde (formalin) test: COHb + formalin remains bright red; oxyhaemoglobin becomes brownish
4. Chemical tests (qualitative):
   • Katayama test: Blood + Reducing agent (tannic acid) → COHb gives crimson-red precipitate
   • Zsygmondy (or Pallauf) test: Blood diluted + NaOH + formaldehyde
5. Post-mortem chemistry: COHb is extremely stable, detectable even months after death and is resistant to putrefaction
6. Air sample analysis from the scene
7. ECG: Prolonged PR interval, AV block, ST depression, bundle branch block

GROUP - C (S/N - 5 Marks)

C3. Alcohol Intoxication - Stages and Medico-Legal Aspects

Stages (refer to Q1-ii above for the 7 stages)

Medico-Legal Aspects of Alcohol Intoxication:

1. Motor Vehicle Accidents: BAC > 80 mg% is the legal limit under the Motor Vehicles Act (India). A doctor may be called to certify intoxication for traffic offenses. Back-calculation using Widmark's formula can estimate BAC at the time of incident.
2. Criminal Cases:
   • Voluntary intoxication is NOT a defence in Indian law (Section 86, IPC) - a person is deemed to have the same knowledge of consequences as if sober
   • Involuntary intoxication (e.g., drugged without consent) may be a partial defence
3. Consent and Contracts: Extreme intoxication may vitiate consent (both medical and legal)
4. Sexual offences: A female in a state of deep intoxication cannot give valid consent; sexual intercourse with her constitutes rape (Section 375 IPC / POCSO)
5. Examination by Doctor: When required to examine an allegedly drunken person, the doctor must document systematically (smell, gait, speech, coordination tests, BAC) and issue a certificate without delay. Breathalyzer test is a bedside confirmatory test.
6. Accidents / Industrial injuries: Compensation may be denied if worker was intoxicated at the time
7. Fitness to drive / plead / stand trial: A doctor may be called upon to give opinion on fitness
8. Fetal Alcohol Syndrome: Chronic maternal alcohol intake → fetal teratogenesis (medico-legal responsibility)

GROUP - D (E/W - 4 Marks)

D1. Antabuse (Disulfiram) is Given

• Disulfiram inhibits aldehyde dehydrogenase (ALDH), the enzyme responsible for converting acetaldehyde to acetic acid
• Normal alcohol metabolism: Ethanol → Acetaldehyde (via ADH) → Acetic acid (via ALDH)
• With disulfiram, acetaldehyde accumulates in blood to levels 5-10× normal

• Flushing, throbbing headache
• Nausea, vomiting
• Palpitations, tachycardia
• Hypotension, dyspnoea
• In severe cases: cardiovascular collapse, convulsions, death

D2. BAC Alone May Not Accurately Reflect Immediate Time of Death or State of Intoxication in a Putrefied Body

1. Post-mortem alcohol production: Putrefactive bacteria (Clostridium species, yeasts, E. coli) can ferment endogenous glucose and carbohydrates to produce ethanol (alcohol) in body tissues and blood. This neo-formed alcohol is indistinguishable chemically from ingested alcohol, falsely elevating measured BAC.
2. Redistribution artifact: After death, alcohol redistributes from the GI tract and other body compartments into blood (especially cardiac blood), causing falsely elevated readings compared to what was present at the time of death.
3. Degradation: Conversely, alcohol may also be partially degraded by bacterial oxidation during prolonged putrefaction, potentially lowering levels.

• Use vitreous humour (eye fluid) as the preferred sample - sealed, protected from bacterial contamination, resists putrefaction; vitreous alcohol levels are more reliable
• Use urine - less subject to post-mortem production
• Collect multiple site samples (cardiac blood, peripheral blood, vitreous, urine) and compare
• Examine for volatile fatty acids (products of bacterial fermentation) as markers of post-mortem alcohol production
• Consider sample ratios and scene investigation

D3. Delayed Gastric Lavage is Also Beneficial in Alcohol Poisoning

1. Alcohol slows gastric emptying - pyloric spasm is produced by alcohol, especially concentrated alcohol. This means a significant amount of alcohol may remain in the stomach for a longer time than expected.
2. Pyloric spasm may trap alcohol in the stomach for up to 4-6 hours after ingestion.
3. Gastric lavage is therefore useful even 2-4 hours after ingestion (unlike many other poisons where it is only useful within 1 hour).
4. In methanol poisoning specifically, delayed gastric lavage is even more valuable as methanol's gastric emptying is slow.

D4. Ethyl Alcohol is Used as an Antidote in Methanol Poisoning

• Both methanol and ethanol are metabolized by the same enzyme - alcohol dehydrogenase (ADH)
• Ethanol has a much higher affinity for ADH (approximately 10-20 times greater affinity than methanol)
• When ethanol is present, it competitively inhibits the metabolism of methanol by ADH
• This prevents conversion of methanol to the toxic metabolites formaldehyde and formic acid
• Methanol thus remains unmetabolized and is excreted unchanged via lungs and kidneys

• IV: 10% ethanol in 5% dextrose - loading 0.6-0.8 g/kg, then infusion
• Oral: Whisky/brandy (40% ethanol) can be used in resource-limited settings

D5. Physostigmine is the Preferred Antidote for Suspected Dhatura Poisoning

• Dhatura contains anticholinergic alkaloids: Atropine, Hyoscine (scopolamine), Hyoscyamine
• Produces anticholinergic toxidrome: "Hot as a hare, Dry as a bone, Red as a beet, Blind as a bat, Mad as a hatter" - hyperthermia, dry flushed skin, mydriasis, tachycardia, urinary retention, ileus, confusion, hallucinations

• Is a cholinesterase inhibitor - prevents breakdown of acetylcholine
• Theoretically reverses anticholinergic effects
• However, physostigmine has serious adverse effects: bradycardia, seizures, asystole, bronchospasm
• It is contraindicated in patients with seizures, cardiac conduction abnormalities, or tricyclic antidepressant co-ingestion
• Its use requires careful monitoring and should only be given by experienced clinicians in specific circumstances

• Neostigmine (a quaternary amine cholinesterase inhibitor) is generally safer and preferred for peripheral anticholinergic effects
• Most toxicologists use symptomatic and supportive treatment as first-line management: cooling, benzodiazepines for agitation/seizures, Foley catheter, dark quiet environment
• Physostigmine, while it can reverse central anticholinergic effects (unlike neostigmine which doesn't cross BBB), is NOT universally "preferred" due to its risk profile