The hallmark of encephalopathy is an altered mental state. Obtaining the history from patients with encephalopathy can be difficult as they are usually confused and disoriented. It is important to obtain the history about the onset, duration, and the progression on the altered mental state. The most common symptoms of encephalopathy are disorientation and confusion, however depending on the underlying cause other symptoms may be noticed.

Obtaining the history is the most important aspect of making a diagnosis of encephalopathy. It provides insight into cause, precipitating factors and associated comorbid conditions. Complete history will help determine the correct therapy and helps in determining the prognosis. Encephalopathy patients are disoriented therefore the patient interview may be difficult. In such cases history from the care givers or the family members may need to be obtained. Specific histories about the symptoms (duration, onset, progression), associated symptoms, drug usage have to be obtained. Specific areas of focus when obtaining the history, are outlined below:

• Onset, duration and progression of symptoms
• Associated symptoms(lethargy, fever, confusion)
• Medications
• History of Trauma
• Symptoms of other organ failure (renal failure, liver failure, adrenal failure)
• Poisons or chemicals ingested
• Co-morbid conditions like diabetes, immunodeficiency
• severe infections
• Any dehydration history for severe loss of fluids
• Exposure to toxic substances
• Trauma

Associated symptoms can provide clues as to the cause of encephalopathy.

• Confusion or agitation
• Changes in behavior and personality
• Progressive cognitive decline
• Forgetfulness
• Disorientation
• Insomnia
• Muscle stiffness or rigidity
• Tremor (particularly a flapping tremor of the hands)
• Difficulty speaking
• Asterixis (rapid momentary loss of tone in the muscles)
• Uncontrollable movements or seizures
• Stupor or coma

Symptoms associated with other diseases and co-morbid conditions.

• Hematemesis
• Nausea and vomiting
• Severe headache
• Dyspnea
• Visual disturbances
• Palpitations, angina
• Hematuria