15.Spinal poisons

Strychnos Nux Vomica

• Type: Tree

• Geographic Distribution: Commonly found in India and other tropical countries.

Toxic Parts of the Plant

• All Parts: The entire plant is poisonous.

• Fruits:

  • Fleshy and contain 3 to 5 seeds.

  • Color: Orange-red when ripe.

• Seeds:

  • Size: Approximately 2 cm diameter and 0.5 cm thick.

  • Shape: Round with one side concave and the other convex.

  • Appearance: Covered with silky fibers resembling coat buttons.

Active Principles and Alkaloids

• Key Alkaloids: The plant contains several toxic alkaloids, including:

  • Strychnine: alkaloid

    • Most toxic, 10 to 20 times more toxic than brucine.

    • Present in seeds.

  • Brucine: alkaloid

    • Present in seeds along with strychnine.

  • Loganin: glycoside

    • Found in bark, leaves, and roots.

    • Less toxic than brucine.

Absorption and Excretion:

• Absorbed from the gastrointestinal tract.

• 80% detoxified in the liver; excreted primarily via urine.

• Trace amounts found in milk, bile, and saliva.

Mechanism of Action

• Glycine's Role: Glycine acts as an inhibitory neurotransmitter affecting post-synaptic potentials in the spinal cord.

• Action of Strychnine:

  • Inhibits the effects of glycine on spinal cord receptors, resulting in excitation.

  • Notable impact on anterior horn cells (e.g., Renshaw cells) causing muscle spasms.

Signs and Symptoms

• Onset: Symptoms appear within 15-30 minutes following ingestion.

• Characteristic Presentation: "Conscious seizure" is a unique feature of strychnine poisoning.

• Initial Symptoms:

  • Bitter taste, feelings of unease, and suffocation.

  • Muscle twitching in the face, neck, trunk, and extremities leading to tetanic convulsions.

• Facial Symptoms:

  • Cyanosis (bluish discoloration) and anxious expression.

  • Prominent eyeballs and dilated pupils.

  • "Kissus sardonicus": Contraction of jaw and facial muscles.

• Posture Changes:

  • Opisthotonus: Arched back due to contraction of back muscles.

  • Emprosthotonus: Forward bending due to abdominal muscle spasm.

  • Pleurosthotonus: Lateral bending of the body.

• Duration: Convulsions last from half a minute to two minutes.

• Pain and Awareness: Patient experiences intense pain yet remains fully conscious and aware.

• Recurring Convulsions: After each episode, the muscles relax completely, but subsequent triggers can cause further convulsions within 5-15 minutes.

Complications and Prognosis

• Fatal Consequences:

  • Severe and frequent convulsions can hinder breathing due to diaphragm spasms, leading to hypoxia, cyanosis, and potentially death.

  • Consciousness remains intact until death.

• Post-Convulsion Complications:

  • Surviving patients might develop lactic acidosis and rhabdomyolysis, risking renal failure.

• Non-fatal Cases: Severity and frequency of convulsions decrease, with total convulsions stopping within 12-24 hours, allowing for recovery.

Dosing and Diagnosis

• Fatal Dose: 60 to 100 mg (approx. 3-5 crushed seeds).

• Fatal Period: 1-2 hours.

• Differential Diagnosis: Tetanus

Difference between strychnine poisoning and tetanus (UQ)

Treatment:

1. Control convulsions in a dark room.

2. Intravenous diazepam or short-acting barbiturates (e.g., pentobarbital sodium: 0.3 to 0.6 gm).

3. Stomach wash (warm water or 1:1000 KMnO4 solution).

4. Administer animal charcoal.

5. Symptomatic treatment for airway maintenance.

Postmortem Appearances:

• Rigor mortis appears early and passes slowly.

• Signs of hypoxia and congestion in internal organs (lungs may be congested and edematous).

• Stomach mucosa congested.

• Strychnine can be found in the body.

• Resists putrefaction and remains detectable even in decomposed bodies.

Physiological Test:

• Injection of suspected material into frog lymph sac causes tetanic convulsions.

Circumstances of Poisoning:

1. Homicidal purposes (mixed with food to mask bitterness).

2. Rarely suicidal.

3. Accidental poisoning via ingestion of seeds.

4. Used as a poison for cattle, dogs, sparrows, etc., and as arrow poison.

Conium Maculatum (Hemlock)

• Historical Importance:

  • Poison used to execute philosopher Socrates in 399 B.C.

• Geographic Distribution:

  • Found in United States, South America, West Asia, and Australia.

  • Grows 3-8ft high.

• Toxic Parts:

  • Seeds and unripe fruits contain the highest concentration of poison.

Active Principles

• Spinal Poisons: Conine, r-coniceine, and six other alkaloids.

Action

• Causes paralysis of motor nerve terminals in the extremities.

• Paralysis gradually spreads to spinal cord and brain.

• Leads to depression of respiratory centers.

Signs and Symptoms

• Upon Ingestion:

  • Burning sensation from mouth to esophagus.

  • Symptoms include nausea, vomiting, and diarrhea.

  • Possible ataxia, mental confusion, tremors.

  • Progressive motor paralysis extends upwards from the extremities.

  • Symptoms may also include blindness and coma.

• Outcome:

  • Death results from respiratory paralysis.

Postmortem Findings

• Froth may be present at the nostrils.

• Lungs are congested and edematous.

• All internal organs show congestion.

• Seed particles may be found in the stomach, with possible congestion of the stomach mucosa.

Circumstances of Poisoning

• Suicidal poisoning is common.

• Cases of homicidal and accidental poisoning have also been reported.