Differentiating organic from psychiatric illness

Introduction

• Differential of psychiatric, medical, behavioural or intoxication
• Ensuring appropriate disposition is crucial in ensuring reduction in morbidity, mortality and cost
• Medical clearance is in essence an imperfect risk reduction strategy to avoid inappropriate admission of medically unwell individuals to psychiatric inpatient settings
• Incidence of missed medical diagnosis for abnormal behaviour is 8-46%
• Close monitoring and repeated reassessment is often necessary

Causes of failure to identify medical conditions

• Inadequate history
• Intoxication
• Inadequate collateral history or record review
• Poor attention to physical examination
• Absence of reasonable MSE
• Uncritical acceptance of medical clearance by MH staff
• Failure to re-evaluate over time

Indicators of organic illness

• First presentation or change in presentation of known MH disorder
• Ask if any medical problems co-exist with apparent mental health issue
• Delirium
  • Abrupt onset change in hours to days
  • Fluctuant mental status
  • Change in cognition – Disorientation, memory deficit, language disturbance
  • Disturbance of LOC – Poor attention, fluctuating or decreased LOC
  • Visual hallucinations, illusions, misinterpretations
  • Change in sleep-wake cycle

Indicators of organic illness

• Drug or alcohol use
• Recent or new medical problems
• Neurological signs or symptoms
• Abnormal vital signs
• FHx of either psychiatric or medical illness e.g. Huntington’s, porphyria, thyroid
• HIV ++

Examination

• Neurological examination should always be performed
• General or specific endocrine signs
• Toxidromes
• Examination for signs of malignancy
• Examination for signs of drug abuse
• Vital signs
  • Must be performed and explained in all patients
• Difficulty in examining due to poor cooperation should be documented so that future clinicians are aware of incomplete initial assessment
• MMSE <20 suggests organic cause
• Age >40 with first psychosis is predictive of organic illness

Low risk patients (Massachusetts)

• Age 15-55
• No acute medical complaints
• No new psychiatric or physical symptoms
• No evidence of substance abuse pattern
• Normal vital signs
• Normal gait and speech with normal memory and concentration

Last Updated on October 7, 2020 by Andrew Crofton