Drug misuse, intoxication and withdrawal: Alcohol: Pathology review

Two individuals are brought into the emergency department, one night. One is 28 year old Brian who was brought in by his friend with complaints of altered consciousness and vomiting.

The friend recalls that Brian had a habit of binge drinking on weekends. On examination, he was disoriented, and had slurring of speech, loss of coordination, and nystagmus.

The second is 2 year old Michelle who’s brought by the mother who reported a seizure episode an hour ago.

Upon further questioning, the mother reveals that Michelle was born 2 months prematurely, was always crying and irritable, and was slow in reaching developmental milestones.

On examination, Michelle has reduced height and weight, a small eye opening, smooth philtrum, and thin lips. A neurological exam shows reduced muscle tone and coordination.

When you obtain a more focused history regarding the mother's pregnancy, she reported drinking 3-5 glasses of wine each night during the 1st and 2nd trimester.

Okay, both Brian and Michelle’s symptoms are due to alcohol. Alcoholic drinks contain the chemical ethanol, which mainly acts in two ways in the brain, one, it acts as an agonist to GABA, which is the brain’s major inhibitory neurotransmitter; and two, it acts as an antagonist of glutamate, which is an excitatory neurotransmitter.

Both these actions produce an overall inhibitory action on the brain’s neuronal circuits. Now, ethanol’s effects vary based on the blood alcohol concentration, or BAC, which is the percentage of ethanol in a given volume of blood.

At a blood alcohol concentration of 0.0 to 0.05%, ethanol produces a relaxed and happy feeling, along with slurred speech and some difficulty with coordination and balance.

At a blood alcohol concentration of 0.06 to 0.15%, there is increased impairment to speech, memory, attention, and coordination, and some individuals can get aggressive and even violent.

Complex tasks like driving can become dangerous, which is why it is illegal to drive in some countries with a blood alcohol concentration of 0.08% or higher.

At a blood alcohol concentration of 0.16 to 0.30%, individuals can experience alcohol poisoning where they blackout or experience periods of amnesia.

Finally, at a blood alcohol concentration above 0.31%, the effect of alcohol can severely suppress breathing and even lead to death.