Consciousness disorders can be sorted into two groups: quantitative and qualitative. Quantitative consciousness disorders (somnolence, sopor, coma) and their basic differential diagnosis will be discussed in this subsection. Qualitative consciousness disorders will be discussed in the next subsection.  

Consciousness disorder is a symptom associated with numerous diagnoses. In the ABCDE approach, findings in other "letters" should be managed as discussed in previous lessons. 

Examination of D should include: 

1.) Determination of the level of consciousness disorder, e.g. by using the AVPU scale: 

• A...Alert - the patient spontaneously interacts. 
• V...Verbal - the patient reacts to verbal stimuli ... corresponds with somnolence.
• P...Pain - the patient reacts to pain stimuli ... corresponds with sopor.
• U...Unresponsive - the patient does not react to pain stimuli ... corresponds with coma.

2.) Examination of pupils: symmetric or asymmetric, pupil diameter (mm), photoreaction.

3.) Basic neurological examination - look for paresis or plegia and signs of lateralization. 

Causes of consciousness disorders, characteristic symptoms and differential diagnosis

1.) Trauma - symptoms vary according to trauma type.

• Diagnosis: patient´s history, physical examination, CT of the brain, and C-spine.

2.) Stroke - ischemic or hemorrhagic - symptoms according to the severity and localization, very often signs of lateralization (face dropping, arm weakness, speech difficulty...).

• Diagnosis: patient´s history, physical examination, CT-angiography of the brain.

3.) Brain tumor - very often associated with signs of intracranial hypertension (headache, vomiting,...) and focal symptoms.

• Diagnosis: patient´s history, physical examination, CT of the brain.

4.) CNS infections - often associated with meningeal signs, headache, nausea, vomiting, photophobia, somnolence, sopor, and sometimes coma.

• Diagnosis: patient´s history, physical examination (fever, petechiae), labs (biochemistry: elevated CRP and procalcitonin (PCT), blood count: elevation of WBC, thrombocytopenia could occur, coagulation tests), CT of the brain or dilated eye exam before cerebrospinal fluid exam. 

5.) Electrolyte imbalance - e.g. hyponatremia, hypernatremia, hypophosphatemia.

• diagnosis: labs - biochemistry: ions,

6.) Intoxication - opioids, alcohol, benzodiazepines...

• Diagnosis: The patient´s history, physical examination (track marks, breath odor, etc.), and labs: Blood and urine for toxicology.
  

7.) Endocrine disease - hypoglycemia, hyperglycemia, myxedema crisis, Addisonian crisis...

• diagnosis:  patient´s history, labs (glycemia, thyroid tests...), physical examination (body temperature, myxedema...).

8.) Organ failure - septic encephalopathy, uremic encephalopathy, hepatic encephalopathy...

• Diagnosis: patient´s history, physical examination (body temperature, hepatopathy, portal hypertension, uremic skin...), and labs (blood count, CRP, PCT, urea, creatinine, ammonia, bilirubin, liver tests, lactate...).

9.) Status epilepticus - convulsive or nonconvulsive.

• diagnosis:  physical examination (seuízures, be careful nonconvulsive status epilepticus), EEG.

10.) Hypovitaminosis and drug interaction - thiamine deficiency, pyridoxine deficiency, malignant neuroleptic syndrome...

• Diagnosis: after excluding other diagnosis.

11.) Others - eclampsia, hypothermia, hyperthermia, catatonia...

Consider the patient´s history and symptoms for prioritization of examination methods to rule out causes from most to least probable. 

Examination and treatment

1.) ABCDE.

• If the patient's level of consciousness according to AVPU is P or U, consider intubation. 
• If the patient is having seizures, consider pharmacological termination of seizures. 

2.) Labs: blood count, coagulation tests, urea, creatinine, ions, ABG,...

• If the glucose disturbance occurs, proceed with treatment (see subsection Glycemia).

3.) CT or CT angiography of the brain.

• Bleeding: Subarachnoidal bleeding, subdural hematoma, epidural hematoma - call neurosurgeon.
• Ischemic CMP - thrombolysis, thrombectomy.
• Tumor, abscess - call neurosurgeon.

4.) Lumbar puncture - if there is suspicion of CNS infection.

• Cloudy CSF - Antibiotics for meningitis (e.g., 3rd generation Cephalosporins).

5.) Toxicology.

• Specific therapy according to the drug type.

6.) Specific lab test - endocrine diseases, organ failure.

7.) EEG.

• Epileptic activity - anticonvulsive therapy.