Differentials
Schizophrenia
SIGNS / SYMPTOMS
Period of psychosis lasts for >1 month. Diagnosis based on patient history and family history and medical records.
INVESTIGATIONS
Clinical diagnosis.
Delusional disorder
SIGNS / SYMPTOMS
Period of psychosis lasts for >1 month. Diagnosis based on patient history and family history and medical records.
INVESTIGATIONS
Clinical diagnosis.
Major depressive disorder with psychotic features
SIGNS / SYMPTOMS
Period of psychosis lasts for >1 month. Diagnosis based on patient history and family history and medical records.
INVESTIGATIONS
Clinical diagnosis.
Recent substance use
SIGNS / SYMPTOMS
Report from patient or family of recent substance use. Physical examination findings may be consistent with effects of substance.
INVESTIGATIONS
Blood and/or urine toxicology: positive for specific substance/s.
Seizure disorder
SIGNS / SYMPTOMS
History of seizures.
INVESTIGATIONS
EEG: typical findings according to seizure type.
MRI and CT brain scan: may demonstrate causative neurological lesions.
Syphilis (quaternary)
SIGNS / SYMPTOMS
History of sexual contact with infected person.
Central nervous system involvement: may be associated with cranial nerve palsy, stroke, dementia, sensory loss, Argyll Robertson pupil.
INVESTIGATIONS
Serum and cerebrospinal fluid: Venereal Disease Research Laboratory (VDRL) test, rapid plasma reagin (RPR), Treponema pallidum haemagglutination (TPHA), fluorescent treponemal antibody absorption (FTA-ABS) positive.
Sarcoidosis
SIGNS / SYMPTOMS
Central nervous system involvement: may be associated with palsies of cranial and peripheral nerves, seizures, meningitis (granulomatous). Pituitary involvement can cause diabetes insipidus.
Pulmonary features include dyspnoea and cough.
INVESTIGATIONS
MRI and CT brain scan: space-occupying lesions.
CXR: bihilar lymphadenopathy, pulmonary infiltrates.
Lung cancer
SIGNS / SYMPTOMS
Central nervous system metastases: focal neurological signs.
Paraneoplastic syndrome: can include neuropathy, myopathy, cerebellar degeneration.
Pulmonary features include dyspnoea, cough, haemoptysis.
INVESTIGATIONS
MRI and CT brain scan brain: metastases
CXR and CT chest scan: mass, coin lesions, pleural effusion, hilar lymphadenopathy.
Thyrotoxicosis
SIGNS / SYMPTOMS
Signs include tachycardia, tremor, thyroid enlargement.
INVESTIGATIONS
TSH: reduced.
Free T4 and free T3: elevated.
Head trauma
SIGNS / SYMPTOMS
History of head trauma. May be accompanied by focal neurological signs.
INVESTIGATIONS
MRI and CT brain scan: may demonstrate focal sequelae of trauma such as haematoma, skull fracture, cerebral oedema.
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