Consultation-Liaison Psychiatry and Neuropsychiatry
What this domain tests
This domain tests your ability to detect delirium, decide capacity, separate psychiatric from medical presentations, and recognise neuropsychiatric syndromes. It rewards systematic rather than intuitive reasoning.
Core rules and concepts
- Delirium screening: the CAM and the 4AT are validated at the bedside; delirium is a medical emergency with high mortality.
- Capacity is decision-specific and assessed by four abilities: understanding the information, retaining it, appreciating its relevance, and communicating a choice. Capacity is not the same as agreeing with the team or acting in one's best interests.
- Medical mimics of psychiatric illness: thyrotoxicosis, B12 deficiency, neurosyphilis, systemic lupus erythematosus, porphyria, steroid psychosis, hypoxia, sepsis, and autoimmune encephalitis.
- Neuropsychiatry: postictal and interictal psychosis in epilepsy, depression and pathological laughing in multiple sclerosis, depression and impulse control disorder with dopamine agonists in Parkinson disease, psychiatric features of Huntington disease and traumatic brain injury.
- Toxin syndromes: serotonin syndrome (clonus, hyperreflexia, agitation) versus neuroleptic malignant syndrome (lead-pipe rigidity, hyperthermia, raised creatine kinase) versus anticholinergic toxicity (dry, flushed, mydriasis, urinary retention).
Worked example
A patient with delirium refuses amputation. He cannot repeat the risks and cannot weigh them, so he lacks capacity for this decision. The team must act in his best interests after the delirium is treated and should re-assess capacity once attention improves.
Traps that cost marks
- Equating capacity with compliance or with best interests.
- Accepting a psychiatric label before excluding a medical cause.
- Missing catatonia in a mute, immobile medical inpatient.