The differential diagnosis of delirium is very similar to that for coma, and one finds the mnemonic VINDICATE useful in this regard.
· V—Vascular disorders of the brain including hemorrhage, embolism, thrombosis, and arteriosclerosis may cause delirium.
· I—Inflammatory disorders of the nervous system that may cause delirium include viral encephalitis, meningitis, syphilis, malaria and other parasites, rabies, and cerebral abscess. Generalized infections, usually when associated with fever, may be responsible.
· N—Neoplasms of the brain are not usually associated with delirium until the end stages at which time the cause will be obvious.
· D—Deficiency disorders that may be associated with delirium include Wernicke encephalopathy, pellagra, and pernicious anemia. Delirium may be associated with degenerative disorders such as Alzheimer disease.
· I—Intoxication by an enormous number of exogenous and endogenous substances may cause delirium. Alcohol, cocaine, heroin, phencyclidine (PCP), marijuana, lead, arsenic, and manganese are just a few of the exogenous substances. Endogenous substances include uremia, ammonia from hepatic failure, hyperinsulinemia, diabetic ketosis, and porphyria. Delirium may be associated with the withdrawal of a patient from alcohol and/or any drug including morphine, cocaine, or tobacco.
· C—Convulsive disorders may be associated with delirium either during or after the seizure.
· A—Autoimmune disorders such as lupus erythematosus are associated with inflammation of vasculitis in the brain causing delirium.
· T—Trauma may cause a concussion, cerebral hemorrhage, or subdural or epidural hematoma leading to delirium.
· E—Endocrine disorders associated with delirium include insulinoma and diabetes.
Approach to the Diagnosis
It is essential to get a history of drug or alcohol use from the patient or family, and a drug screen may be done in most cases. Infection is another common cause. The workup should also include a CBC, sedimentation rate, urinalysis, antinuclear antibody (ANA) analysis, chemistry panel, and electrolytes. A CT scan or MRI of the brain will be necessary in most cases. It may be wise to administer intravenous thiamine and glucose while awaiting the results of blood work. If there is a fever, blood cultures and possibly a spinal tap (after a CT scan or MRI has ruled out a space-occupying lesion) may be indicated. Arterial blood gas analysis and carboxyhemoglobin should be determined. A neurologist or neurosurgeon needs to be consulted early in the workup.
Other Useful Tests
1. EEG (seizure disorder)
2. Venereal disease research laboratory (VDRL) test (neurosyphilis)
3. Carotid sonogram (carotid thrombosis)
4. Four-vessel angiography (transient ischemic attack [TIA])
5. Glucose tolerance test (diabetes, insulinoma)
6. Blood smear for malarial parasites (malaria)
7. Psychiatric consult
8. Urine porphobilinogen (porphyria)
Case Presentation #13
A 13-year-old boy is brought to the emergency room in a delirious state mumbling incomprehensible sentences and rolling his head back and forth. He is occasionally combative. His parents claim he has been this way since he came home two hours ago. His pupils are dilated but there are no other focal neurologic signs.
Question #1. Utilizing the techniques described above, what is your list of diagnostic possibilities at this point?
On questioning the parent's of the friends he was with before he came home this evening, it is discovered that he had taken two tablets of an illegal substance.
Question #2. What is your diagnosis now?