Psychosis on the USMLE Step 2 CK exam

by / Tuesday, 29 June 2010 / Published in Psychiatry

PSYCHOSIS

Psychosis is characterized by:

  • Hallucinations – false sensory perception that is NOT based on real stimuli
  • Delusions – false interpretations of external reality
  • Can be of the paranoid nature, grandiosity, religious, or ideas of reference

This table gives a general overview of the causes of psychosis

DISEASE CHARACTERISTICS
Schizophrenia
  • There is a strong genetic predisposition, onset usually late teens through the 20’s
  • +ve symptoms = hallucinations and/or delusions
  • -ve symptoms = flattened affect
  • Other symptoms include disorganized behavior and/or speech
  • Must last ³ 6 months to be called schizophrenia
  • If lasting 1-6 months called schizophreniform
  • If lasting <1 month it is a brief psychotic disorder (these patients often return to normal baseline functioning)
Schizoaffective disorder
  • Combination of a mood disorder + schizophrenia
Delusional disorder
  • Patient gets non-bizarre delusions
Mood disorders
  • Bipolar and/or depression can cause delusions and in extreme cases may cause hallucinations
Delirium
  • Often seen in patients who have underlying conditions
  • No orientation to person, place, or time
  • Waxing and waning of condition
  • Treatment involves treating the underlying condition
Drugs
  • Cocaine/amphetamines cause paranoid delusions and formication (sensation of bugs crawling on the skin)
  • LSD/PCP cause hallucinations of vision, taste, touch, and scent
Medical causes
  • Endocrine disorders, metabolic disorders, neoplastic disorders, and seizure disorders can cause psychosis

Treatment:

  • If condition is disabling or potentially dangerous to patient or others, hospitalization is required.
  • Pharmacologic therapy is with dopamine antagonists, and the differences amongst the drugs is based on the side effects they produce
  • Improve drug compliance by giving depot form of haldol
  • Psychotherapy to improve social functioning (behavioral treatment to improve social skills, family-oriented treatment for improved familial functioning)
  • Prognosis is dependent of frequency of episodes as well as accompanying symptoms (presence of negative symptoms usually indicates a poor prognosis)
  • Patients who were very high-functioning prior to the psychosis onset have a better prognosis
DRUG ADVERSE EFFECTS
Typical Antipsychotics
Chlorpromazine Low potency, anticholinergic effects, decr movement disorders
Haloperidol High potency, less anticholinergic effect,  incr movement d/o
Atypical Antipsychotics
Clozapine For refractory disease, give weekly CBC (agranulocytosis risk)
Risperidone 1st line, minimal averse effects
Olanzapine 1st line, minimal adverse effects

There are many possible movement disorders associated with the use of antipsychotic medications.  You will likely encounter one on the CK exam.  This table will demonstrate the timeline for certain adverse movement reactions.

DISORDER TIME FRAME CHARACTERISTICS
Acute Dystonia From 4hr – 4 days (4&4)
  • Patient experiences sustained spasms, may be anywhere but MC seen in the neck, jaw, or back.
  • Treatment – IV diphenhydramine (immediately)
Parkinsonism From 4 days – 4 months
  • Patient has cog-wheel rigidity, resting tremor, and shuffling gait
  • Treatment – benztrophine (anticholinergic used in Parkinson’s disease)
Tardive Dyskinesia 4 months – 4 years
  • Involuntary/irregular movements of the head, tongue, lips, limbs, and trunk
  • Treatment – change medications immediately (is a permanent condition)
Akithisia May occur at any time during treatment
  • Patient has a sense of discomfort/restlessness
  • Treat by lower the dose of medication
Neuroleptic Malignant Syndrome May occur at any time during treatment
  • Is a life-threatening muscle rigidity with fever, increased BP and HR, and rhabdomyolysis that appears over 1-3 days
  • Treatment is supportive, stop all offending drugs immediately, give patient dantrolene (Calcium is inhibited from release into cells), and cool the patient

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