Altered Mental Status (Case 52)
Case: The patient is a 25-year-old man without significant past medical history. His girlfriend had called his private physician earlier this morning because he was confused and agitated overnight. He awakened her from sleep at around 2 AM after he fell over a chair and soon after urinated in the corner of their bedroom. He appeared confused and was complaining of a headache. He finally went back to sleep. This morning she was unable to awaken him, and he is warm to the touch.
Subarachnoid hemorrhage (SAH)
In evaluating a patient with altered mental status (AMS), determine whether the patient’s level of consciousness is impaired, whether this is a disorder of thought content, and the time course of the illness. In derangements in level of consciousness that are acute and severe, it may be necessary to act faster to prevent permanent neurologic damage or even death. When assessing level of consciousness, it is essential to be able to very clearly pinpoint the patient’s response to stimulus level; in this sense, it is more important to describe the patient’s state of consciousness according to how he or she is acting or responding (e.g., sleepy, not responding to painful stimuli) than using nonspecific medical jargon such as “lethargic” or “confused.” Such early, rapid assessments of severity and time course help to direct the rest of the examination, workup, and management.
• Disorders of consciousness can affect the level of consciousness (arousal, alertness) as in acute confusional states and coma, or the content of consciousness as in dementia, amnestic disorders, and aphasia.
• Such impairment can be caused by a wide variety of disorders, from structural lesions compromising the RAS to more diffuse bilateral cerebral dysfunction such as that caused by infections, metabolic derangements, or intoxications.
• Gathering a history in these patients can be very challenging and is sometimes not possible. Consequently, every effort should be made to contact caregivers or family members who can fill in important details. Moreover, each part of the complete history may be of significance and will guide your differential diagnosis.
• Keep the initial differential diagnosis very broad, especially with nonspecific associated symptoms such as headache, which may suggest trauma, intracranial or subarachnoid hemorrhage, or meningitis.
• The medication history is of particular importance. Though often overlooked, polypharmacy can lead to accidental medication overdose or exacerbation of side effects and drug–drug interactions. Elderly patients are much more sensitive to the cognitive side effects of many medications, particularly those drugs with anticholinergic properties, often found in many over-the-counter formulations.
• Vital signs: The first step in examination of the patient with AMS is checking basic vital signs, which can give important clues (fever may indicate infection, hypertension may indicate a cerebrovascular event, and tachycardia can be a sign of withdrawal). For patients with impaired level of consciousness, always remember the ABCs (Airway, Breathing, Circulation). If a patient is stuporous (has only localizing responses to noxious stimuli) or comatose, it is critical to ensure that the airway is secure, oxygenation is sufficient, and the patient is not hypotensive. With these patients the rest of the mental status exam cannot be obtained. It is important to proceed in an expeditious and systematic way to determine the underlying etiology.
• General physical exam: In addition to your normal exam, check for neck rigidity (resistance of neck flexion in presence of normal lateral movements), which may suggest meningeal inflammation as in meningitis or SAH. Look for evidence of trauma, such as blood behind the tympanic membrane, bilateral symmetrical black eyes (raccoon eyes), or blood under the skin overlying the mastoid bone (Battle sign), all of which could indicate a fracture to the base of the skull.
• Mental status exam (MSE): The MSE is always the first part of the neurologic exam and should be performed in a systematic fashion, starting with level of consciousness, level of attention, language function, and evaluation of memory. If one of the first two areas is impaired, the remainder of the exam may become difficult or impossible. Very quickly, you must decide whether you can complete the MSE (i.e., attention, language, and memory testing) or whether the patient will be unable to participate with your testing.
• The level of consciousness ranges from alert (in which the patient is resting with open eyes and responding appropriately to verbal stimulation) to comatose (in which the patient is completely unresponsive and cannot be aroused even with vigorous stimulation). In general, as consciousness is increasingly impaired, the intensity of stimulation required for arousal increases, the duration of arousal declines, and the response elicited becomes less purposeful.
A standardized scale of level of consciousness can also help you assess and describe a patient’s state. The most widely used scale is the Glasgow Coma Scale, but the FOUR score (full outline of unresponsiveness) is a recently validated coma scale that provides more neurologic detail and includes brainstem exam and respiratory pattern.
• Attention is the cognitive process of selectively focusing on one relevant stimulus to the exclusion of others. It is formally tested by having the patient perform repetitive tasks like a series of digits and days of the week.
The key feature of an acute confusional state is inattention, which can manifest in three ways: distractibility, perseveration, and inability to focus on an ongoing stimulus. A distractible patient shifts attention from the examiner to another stimulus such as noise in the hallway. Perseveration is the repetition of phrases, answers, or tasks from previous questions.
• The essential elements of language function are comprehension, fluency, naming, repetition, reading, and writing. Fluent aphasia sometimes leads to the false impression of acute confusion; therefore, careful examination of language is important in every patient with AMS or acute confusional state.
• Remainder of neurologic exam: In general, you should be as complete as possible in your neurologic exam, even in patients capable of only limited cooperation. In patients with severely impaired level of consciousness, you may not be able to reliably examine sensation, motor function, and coordination. The neurologic exam for stuporous or comatose patients should focus on brainstem function and the presence of other focal neurologic signs.
• The cranial nerve exam for the comatose patient typically includes pupils and their response to light; gaze and oculocephalic reflex; response to caloric stimulation; breathing pattern; and corneal, cough, and gag reflexes. The motor exam in the comatose or stuporous patient is very different from that in the awake and cooperative patient and, instead of testing strength in different muscle groups, focuses on motor tone, reflexes, and overall motor response to painful stimulation.
Diagnostic testing can be extremely helpful in many cases, but your clinical findings should guide your workup and not vice versa. As a result, there is no one algorithm for evaluating patients with AMS, and each case should be considered individually. The common indications and utility of various tests are discussed below.