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Mental Health Nursing · Chapter 5

Four Pathways and the Price of Blocking Them

Dopamine travels four routes, and a tablet cannot choose between them: the benefit in one pathway arrives with movement, hormonal and cognitive costs in the other three. Trace each pathway below, then name nine bedside pictures — because at the bedside you sort them by onset and by muscle tone, not by the drug chart.

The four dopamine pathways

midbrain limbic prefrontal cortex striatum pituitary

Name it at the bedside

0 of 9 named

What that costs, and what to do

Choose a pathway, or name a pictureBlocking dopamine in the mesolimbic tract is the therapeutic effect. The same tablet reaches three other tracts on the way, and everything students call “the side effects of antipsychotics” is really the bill for that.

Sort it by the clock

Acute dystonia Akathisia Parkinsonism NMS (often after a dose rise) Tardive dyskinesia hours days weeks months years
Time of onset does most of the diagnostic work. Hours means dystonia. Days to a couple of weeks means akathisia. Weeks means parkinsonism. Months to years means tardive. Days to weeks with a fever and rigidity, especially after a dose increase, means neuroleptic malignant syndrome until proven otherwise.

Muscle tone is the discriminator

Serotonin syndromeOnset over hours. Provoked by adding a serotonergic agent. Hyperreflexia and clonus, especially at the ankles. Dilated pupils, hyperactive bowel sounds, diarrhoea, tremor, agitation. Tone is jerky and hyperactive.
Neuroleptic malignant syndromeOnset over days. Provoked by dopamine blockade or the abrupt withdrawal of a dopamine agonist. Lead-pipe rigidity with hyporeflexia, normal bowel sounds, hyperthermia above 40°C, autonomic instability, markedly raised creatine kinase. Tone is rigid.
The drug chart will not settle it — plenty of people take a serotonergic antidepressant and an antipsychotic at the same time. Examine the reflexes, the pupils and the bowel sounds. Jerky and hyperreflexic points serotonergic; rigid and hyporeflexic points neuroleptic. The nursing response is the same shape in both: stop the offending agent, call for help, protect the airway, cool actively, run fluids as ordered, monitor rhythm and urine output, and document a temperature trend rather than a single number.