Differentials
Sympathomimetic intoxication
SIGNS / SYMPTOMS
Several drug intoxications can produce sympathomimetic effects including diaphoresis, hypertension, tachycardia, hyperthermia, agitation, and seizure.
Excited delirium syndrome can result in sudden cardiac arrest.
INVESTIGATIONS
This is a clinical diagnosis.
Encephalitis
SIGNS / SYMPTOMS
Patients usually present with abnormalities of the brain parenchyma, which may include but are not limited to hemiparesis, sensory motor deficits, and confusion/disorientation.
INVESTIGATIONS
Lumbar puncture, blood cultures, and FBC to assess leukocytosis or leukopenia; electrolyte panel to assess for abnormal electrolytes such as hyponatraemia. Polymerase chain reaction and serology testing can be performed based on suspected pathogens.
Meningitis
SIGNS / SYMPTOMS
Fever, nuchal rigidity, and change in mental status are common features although not all patients present with this triad. Other features include but are not limited to photophobia, skin rash, or cranial nerve palsies.
INVESTIGATIONS
Lumbar puncture, blood cultures, and FBC to assess leukocytosis or leukopenia; electrolyte panel to assess for electrolyte abnormalities such as hyponatraemia.
Hypoglycaemia
SIGNS / SYMPTOMS
Symptoms include but are not limited to tremor, anxiety, palpitations, and neuroglycopenic symptoms, such as drowsiness, seizure, and loss of consciousness.
Wernicke's encephalopathy
SIGNS / SYMPTOMS
Likely clinical features are confusion, ataxia, and ophthalmoplegia.
INVESTIGATIONS
This is a clinical diagnosis. There are no tests that are available in the emergency setting. Routine work-up for acute delirium should be performed to rule out other causes.
CT or MRI of the brain may help to exclude other causes and show structural lesions in the mid-brain and periventricular region. Diagnostic imaging should not be used to determine the diagnosis of Wernicke's encephalopathy in an emergency setting.[54][55]
Head injury
SIGNS / SYMPTOMS
Patient or witness report of injury, in particular dangerous mechanisms (e.g., a pedestrian or cyclist struck by a motor vehicle, an occupant ejected from a motor vehicle, or a fall from a height of >1 metre or 5 stairs); retrograde amnesia; loss of consciousness; may cause seizures.[36]
Always suspect head injury in patients who are withdrawing from alcohol; have a low threshold for requesting a CT head.
INVESTIGATIONS
Request a CT head in patients with suspected head injury plus at least one of the following:[36] Glasgow Coma Scale (GCS) <13 on initial assessment in the emergency department [ Glasgow Coma Scale Opens in new window ] ; GCS <15 at 2 hours after the injury on assessment in the emergency department; an open or depressed skull fracture; any sign of basal skull fracture (haemotympanum, 'panda' eyes, cerebrospinal fluid leakage from the ear or nose, Battle's sign); focal neurological deficit; post-traumatic seizure; >1 episode of vomiting.
Alcoholic ketoacidosis
SIGNS / SYMPTOMS
A metabolic complication of alcohol use and starvation characterised by hyperketonaemia and anion gap metabolic acidosis without significant hyperglycaemia. Causes nausea, vomiting, and abdominal pain.[104]
Present in 25% of patients who are admitted to hospital with an alcohol-related disorder.
INVESTIGATIONS
Anion gap metabolic acidosis on blood gas.
Elevated blood ketones.
No significant hyperglycaemia.
Hepatic encephalopathy
SIGNS / SYMPTOMS
Patients present with sleep disturbances and/or neurological symptoms such as bradykinesia, asterixis, or focal neurological symptoms.
INVESTIGATIONS
Abnormal liver function tests.
Electrolyte abnormalities (e.g., hyponatraemia).
Elevated ammonia levels.
Benzodiazepine withdrawal
SIGNS / SYMPTOMS
Symptoms are subtle and depend on the half-life of the medication. Onset may vary from 2 days to a week. Symptoms include anxiety, tremors, hallucinations, delusions, seizures, and hypothermia.[140]
INVESTIGATIONS
This is a clinical diagnosis.
Opioid withdrawal
SIGNS / SYMPTOMS
Symptoms vary from mild drug craving to abdominal cramps, autonomic hyperactivity, rhinorrhoea, nausea, vomiting, and diarrhoea.[140]
INVESTIGATIONS
This is a clinical diagnosis.
Anticholinergic poisoning
SIGNS / SYMPTOMS
Ingestion of xenobiotic with anticholinergic property.
Symptoms include mydriasis, tachycardia, flushed skin, urinary retention, dry skin, hallucination/delirium.[140]
INVESTIGATIONS
This is a clinical diagnosis.
Thyrotoxicosis
SIGNS / SYMPTOMS
Is more common in women in early adulthood and is characterised by heat intolerance, muscle weakness, and proptosis that helps to distinguish from other diseases. Nervousness, gastrointestinal hypermotility, hair loss, and cardiovascular manifestations are common.[141]
INVESTIGATIONS
Low levels of thyroid-stimulating hormone and elevated triiodothyronine (T3) and thyroxine (T4) in Graves' disease and elevated T3 in thyroid toxicosis. A radioactive iodine scan is helpful in identifying the pattern of uptake in the thyroid gland.
Alcohol-induced psychotic disorder with hallucinations
SIGNS / SYMPTOMS
Previously known as alcoholic hallucinosis. A rare condition in chronic heavy drinkers. Characterised by the presence of hallucinations that are a direct consequence of alcohol use.[142] Symptoms do not occur exclusively during hypnogogic or hypnopompic states, and are not related to other causes (e.g., epilepsy with visual symptoms, schizophrenia).[142]
INVESTIGATIONS
Accepted criteria for diagnosis come from the International Statistical Classification of Diseases and Related Health Problems, 11th revision (ICD-11).[142]
Schizophrenia
SIGNS / SYMPTOMS
Onset is usually insidious and is preceded by social withdrawal, lack of interest, poor hygiene, and bizarre thinking. Onset is usually in early adulthood.[143]
INVESTIGATIONS
Accepted criteria for diagnosis come from the Diagnostic and Statistical Manual for Mental Disorders, fifth edition, text revision.[137]
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