Prehospital Academy lesson 28.2
Acute Psychosis: Neurological Foundations and Tactical Management
In emergency medicine, acute psychosis is defined as a profound disconnection from reality, often manifesting as hallucinations, delusions, or disorganized thinking. For the EMT, these encounters represent high-acuity calls where the patient's internal reality can trigger unpredictable behavioral responses. This companion explores the neurobiological drivers of psychosis, the "medical masquerade" of delirium, and the tactical framework for field assessment and de-escalation.
Neurobiology of the Psychotic Break
Psychosis is not a single disease but a clinical state rooted in neurochemical dysregulation. To provide effective care, the EMT should understand the primary biological hypotheses:
The Dopamine Hypothesis: Most antipsychotic medications are dopamine antagonists. Excessive dopamine signaling in the mesolimbic pathway is associated with "positive" symptoms (hallucinations and delusions). Conversely, a deficit in the mesocortical pathway leads to "negative" symptoms (social withdrawal and flat affect).
Glutamate Disruption: NMDA receptor dysfunction is linked to cognitive disorganization. This explains why dissociative anesthetics like PCP or Ketamine, which block NMDA receptors, can induce symptoms identical to acute schizophrenia.
Clinical Typology: Positive vs. Negative Symptoms
Psychotic symptoms are categorized based on whether they "add" to or "subtract" from a person's normal experience:
Positive Symptoms (The "Additions"): Hallucinations (perceiving what is not there), Delusions (fixed false beliefs), and Disorganized Speech (word salad).
Negative Symptoms (The "Deficits"): Alogia (poverty of speech), Anhedonia (inability to feel pleasure), and Avolition (lack of motivation).
Clinical Relevance: Positive symptoms often drive the behavioral emergencies that lead to EMS activation, while negative symptoms can make it difficult to obtain a history or assess the patient's underlying level of distress.
The "Medical Masquerade": Delirium vs. Psychosis
The most critical decision an EMT makes is determining if a patient is experiencing a primary psychiatric event or a secondary medical emergency (delirium).
Delirium (The Medical Emergency): Characterized by fluctuating consciousness, disorientation, and acute onset. Causes include hypoglycemia, sepsis, toxins, or neurological events (stroke).
Primary Psychosis (The Psychiatric Event): Patients typically have clear consciousness but distorted thought content. They are often oriented to person/place/time, despite their hallucinations.
The COAST MAP: Prehospital Mental Status Exam
The COAST MAP mnemonic provides a structured way to assess and document the patient's neurological "vitals" in the field:
Consciousness: Assess AVPU and focus.
Orientation: Person, Place, Time, and Event.
Activity: Psychomotor agitation or catatonia.
Speech: Pressured, disorganized, or poverty of speech.
Thought Content: Delusions or suicidal/homicidal ideation.
Memory: Recent vs. remote recall.
Affect and Mood: Does the emotional expression match the situation?
Perception: Hallucinations (no stimulus) vs. Illusions (misinterpreted stimulus).
Pharmacological Complications: Dystonic Reactions
Patients treated with dopamine antagonists (e.g., Haloperidol) may experience Extrapyramidal Side Effects (EPS). The most acute is a Dystonic Reaction, characterized by painful, involuntary muscle spasms of the neck (torticollis), jaw (trismus), or eyes (oculogyric crisis). While terrifying for the patient, it is rapidly reversible with Diphenhydramine (Benadryl).
Critical Thinking Questions
Explain why a patient with "clear consciousness" and hallucinations is more likely to be experiencing schizophrenia than a medical emergency like sepsis.
How does the **NMDA Receptor** theory explain the "psychotic-like" effects of drugs like PCP?
Compare and contrast a **Hallucination** and an **Illusion**. Give a field example of each.
Why is it critical to check a blood glucose level on EVERY patient presenting with new-onset psychosis?
You are treating a patient with a "fixed, upward gaze" and a locked jaw after taking an antipsychotic. What is the physiological cause, and what is your immediate treatment?