Last Authored: Oct 2016, Aaron Gross
Draft: Pending final review
Introduction
Altered level of consciousness (LOC) or altered mental status (AMS) refers to various symptoms regarding poor arousal or awareness. Normal consciousness is characterized by Arousal (quantity of consciousness) and Awareness (quality of consciousness).
Manifestations of Altered LOC include
- Confusion/ Disorientation
- Decreased Arousability
- Inattention
- Altered behavior or emotions
- Disorganized thoughts
- Amnesia (memory loss)
Causes of altered LOC vary from obvious to occult and can be benign or life-threatening. The diabetic patient with low blood sugars is a simple diagnosis, but may result in dangerous complications. Other cases are multifactorial and require careful clinical investigation over time to determine the diagnosis. Therefore each case must be taken seriously and receive a thorough work up.
Delirium is a general term for altered LOC that is acute in onset, fluctuates over time, and is due to a medical condition or drug. Unlike syncope or seizure, it persists for hours to days. It is commonly diagnosed using the Confusion Assessment Method (CAM), with criteria being 1 + 2 + 3 or 4, and caused by a general medical condition or drug
- Inattention
- Acute onset and fluctuating course
- Disorganized thinking (confused)
- LOC alteration: increased or decreased awareness & sensitivity to environment; may be hypoactive, hyperactive, or mixed
Pathophysiology
Consciousness is mediated by two major structures in the brain. The reticular formation, located in the brainstem pons & midbrain, mediates arousal, while the cerebral Cortex mediates awareness
For the brain to function normally and maintain a normal LOC, several requirements must be met:
- Blood flow, with sufficient oxygen, glucose, and electrolytes
- Normal Temperature
- Absence of Harm, including physical disruption, toxins or drugs, and abnormal electrical activity
Causes
- Drugs
- Infection
- Metabolic
- Structural
Altered level of consciousness is caused by two major categories:
- General Medical Conditions (numerous causes)
- Psychiatric Conditions (anxiety, mood dysregulation, psychosis, dementia)
Although psychiatric conditions are common, it is important to first rule out medical conditions.
Drugs
Drugs may alter LOC via toxicity or withdrawal:
Recreational drugs
Anticholinergics
Psychogenic drugs
|
Analgesics
Anti-hyperglycemics Cardiac
Poisons
Syndromes
|
Infections
Many infections can lead to delirium, including:
- Sepsis
- Pneumonia
- Urinary tract infection
- Intraabdominal infection
- Cellulitis or Abscess
- C. difficile
- Viral syndrome
- Meningitis
- Malaria
- Encephalitis
Metabolic
Chemistry
- Hypo-/hypernatremia
- Hypercalcemia
- B12 Deficiency
- Thiamine Deficiency (Wernicke’s Encephalopathy)
Endocrine
- Low/ High Glucose
- Hyper/ Hypothyroidism
- Addisonian Crisis
Organ Failure
- Liver (Hepatic Encephalopathy)
- Kidney (Uremic Encephalopathy)
Vitals
- Low/ High Temperature
- Hypoxia
- Hypercarbia (CO2 Narcosis in COPD)
- Shock (various causes)
- Hypertensive Encephalopathy
Structural
Structural insults constitute direct damage to the brain
- Trauma
- Stroke/ Transient Ischemic Attack
- Space Occupying lesion
- Tumor
- Hydrocephalus
- Intracranial hemorrhage
- Seizure (Non-convulsive)
- Complicated Migraine
Other Causes of Altered LOC
Most causes of altered LOC produce a change in mental status lasting for hours to days. However, there are three common illnesses that produce very short-lived change in mental status. These include Seizure, Syncope, and Transient Ischemic Attack (TIA).
| Symptom | Seizure | Syncope | Transient Ischemic Attack |
| Level of Consciousness | Unconscious | Unconscious | Confused or Agitated |
| Duration of alerted LOC | >1 min | <1 min | >1 min |
| Duration of Post-ictal symptoms | 15 min – hours | <5 min | <15 min |
| Limb movements | Focal or Tonic-Clonic or None | Tonic-Clonic or None | None |
| Urinary incontinence | Common | None | None |
| Tongue Biting | Common | None | None |
| Focal Neurologic signs | Sometimes | None | Always |
Lastly, and rarely, some states can mimic altered LOC because the patient is unable to physically interact with their environment. These include:
- Paralysis
- Locked-in Syndrome (due to pons damage)
- Neuromuscular disease
- Psychogenic unresponsiveness
- Akinetic Mutism
Approach
Because the causes of altered LOC are so numerous, and vary from severe to benign, it is essential to have an organized approach for diagnosis and management. A patient should be approached in the following order:
Resuscitation – ABCDE
All patients must be stabilized before a thorough evaluation can be performed. Altered LOC may be due to problem with a patient’s ABCs, but worsening LOC can lead to problems with the ABCs, so frequent reassessment is needed to determine if further intervention is required.
A – Airway
Ensure that the airway is patent, and that no obstruction is causing altered LOC through hypoxia. Suctioning and positioning may be used to open the airway. Use the Glasgow Coma Scale (GCS) to determine whether the patient is alert enough to protect their airway from aspiration. If GCS is 8 or less, they should be intubated. If trauma is suspected, utilize C-spine precautions while establishing an airway.
| Glasgow Coma Scale | ||
| Eyes | Verbal | Movement |
| 4 – Spontaneously looking around
3 – Opens eyes to Loud voice 2 – Opens eyes to Pain 1 – None |
5 – Oriented
4 – Confused 3 – Inappropriate words 2 – Incomprehensible sounds 1 – No Sounds |
6 – Obeys commands
5 – Localizes to pain 4 – Withdraws to pain 3 – Flexion posturing 2 – Extension posturing 1 – None |
B – Breathing
Providing low flow oxygen is a safe and often important early treatment. Monitor the patient’s respiration rate, O2 saturation. Ensure that they have good air entry bilaterally, no tracheal deviation, and normal work of breathing.
C – Circulation
Establish IV access immediately as this will be needed for blood work and may be required for IV fluids. If hemodynamically unstable, establish 2 large bore IVs in the antecubital veins, give a bolus of 1-2L of normal saline, and consider cross matching the patient’s blood with a few units in the blood bank. Assess for sources of bleeding and apply direct pressure. Monitor the patient’s ECG, heart rate, and blood pressure.
D – Disability
Assess the patient’s level of neurological disability by determining their GCS, pupillary reflex, and asking them to move all four limbs. Any focal neurologic deficits may indicate a raised intracranial pressure and can be treated empirically by raising the head of the bed. If the patient is seizing, treat with benzodiazepines and/or phenytoin. Obtain a bedside glucose level and temperature.
E- Exposure
Fully undress the patient, cut their clothes off if needed, to perform a rapid head to toe exam searching for signs of trauma, infectious sources (catheters, rashes), and transdermal drug patches.
Empiric Reversal Agents
Certain treatments can be given before making a diagnosis which are safe, but may be life saving. These include DONT:
- Dextrose, in case of severe hypoglycemia
- Oxygen, in case of hypoxia
- Naloxone, for opioid toxicity
- Thiamine, for Wernicke’s encephalopathy; give before dextrose, as IV dextrose will worsen a pre-existing thiamine deficiency
Collateral History
One of the greatest challenges of diagnosing the cause of altered LOC is that the patient is unable to provide a good history. A collateral history from witnesses or those who know the patient’s circumstances, is very important. Sources for a good history include first responders, friends/ relatives, caregivers (eg from a nursing home), and previous health records.
A medication review, potentially with support from pharmacy, can reveal medications that could be contributing to changes in mental status.
The onset and duration of an altered LOC can narrow the list of potential causes significantly. Onset may be
- abrupt (over seconds)
- acute (over hours)
- subacute (over days)
- chronic (over months)
Abrupt onset within seconds may suggest syncope, whereas subacute onset over days excludes it.
Duration may be:
- transient
- static
- progressive
- fluctuating
- relapsing
Altered LOC lasting for less than a minute suggests syncope, but if it persists for hours it may be a stroke, and if it progressively worsens over days it could be a tumor.
Events Surrounding the Illness: Try to obtain a full picture of the events leading up to the patient’s present circumstances. Determine when they were last seen functioning at their baseline. Ask about symptoms in the last few days. Determine the exact location they were found. If it was beside a bed or a chair, it may suggest they had orthostatic hypotension after standing up. If found it the washroom, they may have experience vasovagal syncope from straining on the toilet. If covered in urine or with blood on their tongue, it suggests a seizure.
Baseline Function: Understand the patient’s living situation and their level of independence to perform their activities of daily living (ADLs). If they live alone and have poor mobility, they may not be taking proper care of themselves.
Recent Health Status: Determine their past medical history, psychiatric history, medications, and allergies. Ask about recent hospitalizations, surgeries, illnesses, or frequent falls, as the patient may be experiencing a complication of their previous illness.
Physical Exam
Various elements of the physical exam may reveal clues about the potential cause of altered mental status, as described below.
Temperature
| Fever | Infection, environmental exposure, drugs, acute inflammation, malignancy |
| Hypothermia | Shock, environmental exposure |
Neurological
| GCS | Measures Arousability |
| Pupillary reflex | CN 2/3 & midbrain |
| Corneal reflex | CN 5/7 & pons |
| Gag reflex | CN 9/10 & medulla |
| Reflexes & Movement of all 4 limbs | Asymmetry suggests structural lesion |
| Unilateral weakness or numbness | Stroke |
Head and Neck
| Head Trauma | Bleeding or bruising
– Around eyes – Racoon eyes – Behind ears – Battle’s sign – Behind eardrum – Hemotympanum Clear cerebrospinal fluid leaking – From ears – Otorrhea – From nose – Rhinorrhea |
| Pupils | Unilateral, dilated, unreactive (intracranial mass or bleed)
Pinpoint (sedative toxicity esp. opioids) Dilated (stimulant toxicity or sedative withdrawal) Nystagmus (PCP or alcohol) |
| Fundoscopy | Papilledema (intracranial mass or bleed) |
| Breath odor | DKA, alcohol |
| Tongue bite marks | Seizure |
| Neck stiffness | Meningitis |
| Thyroid enlargement | Thyroid disease |
Respiratory
| Respiration Rate | High (ASA, Stimulants)
Low (Opioids, Sedatives) Cheyne-Stokes breathing (intracranial pathology, CHF, CO poisoning) Kussmaul breathing (DKA) |
| SpO2 | Hypoxia |
| Crackles | CHF, pneumonia |
| Wheeze | COPD, asthma |
Cardiovascular
| Volume status | Shock |
| Heart sounds | Arrhythmia
Muffled (cardiac tamponade) Murmur (endocarditis, MI) |
| Blood Pressure | Low (Shock)
High (intra-cranial pathology) |
Abdomen
| Distended | Bowel obstruction, AAA |
| Rigid or Rebound tenderness | Acute inflammation, bowel perforation, AAA |
Skin
| Sweat | Dry & hot skin (anticholinergic)
Sweaty & hot skin (stimulant) |
| Bleeding, bruising | Hemorrhagic shock, intracranial bleed |
| Track marks | IVDU |
| Indwelling catheters | Line sepsis |
| Rash | Infection, Anaphylaxis |
| Jaundice | Hepatic encephalopathy |
Investigations
Lab tests to consider, along with the cause(s) of abnormal findings, include:
- CBC (infection)
- creatinine, BUN (renal failure)
- liver enzymes, ammonia (hepatic encephalopathy)
- electrolytes (low or high Na, low Calcium, low Magnesium)
- alcohol level (intoxication or withdrawal)
- TSH (hypothyroidism)
- serum drug levels (acetaminophen, ASA)
- urine drug screen (various drugs, including BZPs, opioids)
- blood culture (sepsis)
- lactate
- urinalysis (infection)
- glucose, serum osmolality (hypoglycemia, DKA)
- B12 (deficiency)
- amylase, lipase (pancreatitis)
- beta-hcg (pregnancy)
- lumbar puncture (meningitis)
- arterial blood gas (hypoxia, acid-base disorder)
- CK, troponin (acute coronary syndrome)
- C difficile toxin
- INR, PTT (concern for intracranial bleed)
- serum cortisol (Addison’s crisis)
- carbon monoxide levels (poisoning)
Imaging and other tests to consider include:
- CXR (pneumonia)
- ECG (arrhythmia, wide QRS complex, long QT or torsades with medication toxicity)
- CT head (concussion, Intra-cranial bleed, stroke, tumor, cerebral atrophy, hydrocephalus)
- C-spine X-ray (trauma)
- EEG (seizure)
- MRI (occult intra-cranial bleed, cerebral atrophy)
Disposition
Most patients who present with altered LOC require hospitalization. However, some patients may be treated and observed if the cause is clear and easily reversible, such as seizure with known disorder, hypoglycemia, or opioid overdose.
Questions to consider while determining disposition include:
- How sick is the patient?
- Do you know what caused the symptoms?
- Has the problem been fixed, or is a solution readily available?
- Is further deterioration likely?
- Does the patient have support at home in case they decompensate?
- Is follow up medical care in place?
It can be particularly challenging if the patient desires to leave, but there is concern about their mental status affecting their decision making capacity. These cases require a careful analysis of the situation, involving family, friends, and other supports to ensure safety.
Summary
Altered LOC has a broad differential diagnosis and must be treated as a medical emergency. Causes can be organized into 4 broad categories: Drugs, Infection, Metabolic, Structural (DIMS).
Before performing a full assessment, ensure the patient is stable, assessing their ABCDEs. Since, the patient cannot speak for themselves, multiple people should be contacted to obtain a thorough collateral history regarding the events leading up to the illness as well as the patient’s baseline function and medical history. The timing of onset and duration is very helpful in narrowing the differential diagnosis. Physical exam can rule out many dangerous causes of altered LOC, while a thorough workup with labs and imaging can rule out occult causes.
Most patients require hospitalization until their physician is confident they will not regress into altered LOC or has supports at home if they do.
Resources and References
Morrisey T. The Approach To Altered Mental Status. CDEM Curriculum.