What is Other Specified Delirium?

Delirium is an acute disturbance in attention and awareness with a fluctuating course and cognitive disturbance. “Other Specified Delirium” is used when delirium is present but requires a descriptive qualifier (e.g., atypical duration, mixed hypoactive/hyperactive features, or delirium superimposed on severe sensory impairment) or when there is insufficient information to assign a precise subtype.

When to use this label

• Atypical presentations (e.g., prolonged hypoactive delirium lasting weeks without clear medical explanation).
• Delirium with unusual precipitants (e.g., exposure to novel toxins, rare infections).
• Mixed presentations where features overlap multiple subtypes and a single label is unhelpful.
• When key diagnostic information is pending (e.g., awaiting imaging, CSF, or collateral history).

Common precipitating factors

• Infections (UTI, pneumonia, sepsis).
• Metabolic disturbances (electrolyte imbalance, hypoxia, hepatic/renal failure).
• Medication effects or withdrawal (benzodiazepines, opioids, anticholinergics, alcohol withdrawal).
• Acute neurological events (stroke, intracranial haemorrhage, seizures, status epilepticus).
• Endocrine crises (thyroid storm, adrenal insufficiency), toxins, and post-operative states.

Clinical features to recognise

• Acute onset and fluctuating course of inattention and reduced awareness.
• Disorientation, memory impairment, language disturbances and perceptual disturbances (e.g., illusions, hallucinations).
• Changes in psychomotor activity — may be hypoactive (lethargy), hyperactive (agitation) or mixed.
• Sleep–wake cycle disturbance and emotional dysregulation (anxiety, fear, apathy).

Assessment — urgent priorities

1. Confirm delirium using a validated tool (e.g., CAM, 4AT) and document baseline cognitive status if possible.
2. Identify and treat reversible causes immediately (ABC — airway, breathing, circulation; oxygen if hypoxic).
3. Medication review — stop or reduce offending drugs; consider withdrawal syndromes.
4. Obtain collateral history to establish baseline cognition and timeline of change.
5. Screen for focal neurological signs, seizures or head injury requiring urgent imaging.

Investigations — focused and timely

• Basic bloods: CBC, electrolytes, renal & liver function, glucose, calcium, magnesium, phosphate.
• Oxygen saturation and arterial blood gas when respiratory compromise suspected.
• Infection screen: blood cultures, urine analysis, chest x-ray, relevant cultures.
• Drug levels/toxicology when overdose or toxicity suspected.
• Neuroimaging (CT/ MRI) if new focal signs, head trauma, or atypical prolonged course.
• EEG if non-convulsive status epilepticus or persistent altered consciousness is a concern.
• Consider CSF analysis if encephalitis or meningoencephalitis suspected.

Management principles — STEPWISE

The goal is rapid identification and treatment of causes, minimising harm, managing distressing symptoms and preventing complications. Follow a STEPWISE approach: Stabilise, Treat causes, Environment, Pharmacology (if needed), Investigate, Support, Evaluate and prevent.

Stabilise

• Ensure airway, breathing, circulation and treat hypoxia or hypotension.
• Manage agitation that threatens safety (non-pharmacological de-escalation first).

Treat causes

• Antibiotics for sepsis, correct metabolic derangements, manage withdrawal syndromes.

Environment

• Provide orienting cues (clock, calendar), reduce sensory overload, ensure adequate lighting and familiar items from home.
• Promote sleep hygiene and maintain day–night cues.

Pharmacology (when necessary)

• Prefer non-pharmacological strategies. Use antipsychotics (e.g., low-dose haloperidol or atypical agents) only for severe agitation, psychosis, or risk to self/others — lowest effective dose and short duration.
• Avoid benzodiazepines except for alcohol or benzodiazepine withdrawal.
• Pain control, treat constipation and urinary retention which may worsen delirium.

Investigate

• Escalate investigations based on clinical suspicion (EEG, CSF, MRI).

Support

• Engage family/caregivers, provide reassurance and education, and involve multidisciplinary teams (geriatrics, psychiatry, neurology, pharmacy, occupational therapy).

Evaluate & prevent

• Review medications, develop prevention plan for future hospitalisations and address modifiable risk factors (polypharmacy, dehydration, sensory impairment).

Key takeaways

• Use the category to communicate atypical or provisional delirium diagnoses — but prioritise treating reversible causes immediately.
• Combine prompt medical treatment, non-pharmacological care and cautious pharmacological measures when necessary.
• Multidisciplinary involvement and clear documentation improve outcomes and continuity of care.