Past exam of the medicine course of the University of Oxford / 1867 / Second examination / Forensic medicine and hygiene / 4

What are the symptoms of poisoning by Strychnia ?

Strychnine poisoning characteristically produces rapidly recurring, intensely painful generalized muscle spasms, precipitated by slight sensory stimuli, with consciousness initially preserved. “Strychnia” is the historical name for strychnine.

Following ingestion, manifestations commonly begin within roughly 15–60 minutes, although exposure route and amount alter the time course. Early features include apprehension, restlessness, heightened sensitivity and stiffness or twitching of the muscles, especially about the neck and back. The patient can then develop violent, generalized muscle spasms with rigid limbs and backward arching of the trunk, termed opisthotonus. Jaw closure and contraction of the facial muscles can produce trismus and risus sardonicus. The respiratory muscles may become fixed, causing difficulty breathing and cyanosis.^[ref]

Attacks may be triggered by touch, a noise, light or attempts to move the patient. During the intervals the muscles may relax substantially, and the patient may remain lucid and fearful of the next attack. Repeated contractions cause exhaustion, sweating and hyperthermia; severe cases develop acidosis, rhabdomyolysis and acute kidney injury. Death can result from respiratory failure. Consciousness can be lost late through hypoxia, so preserved awareness is a characteristic early clue, not an invariable requirement.^[ref]

This pattern helps distinguish the condition from many epileptic seizures, in which impaired awareness and a postictal state are common, and from tetanus, whose evolution is usually slower and whose rigidity tends to persist between attacks. The distinction is not absolute and symptoms alone do not prove the particular poison. A convincing forensic diagnosis combines the clinical sequence and exposure history with toxicological analysis.

The modern explanation is blockade of inhibitory glycine receptors in the spinal cord and brainstem, leaving reflex motor activity excessively excitable. This explains why trivial stimulation can cause a massive contraction. The receptor explanation is a later interpretation of the recognizable nineteenth-century syndrome.^[ref]