Altered Level of Consciousness (ALC)
Basics
When something interferes with interactions in the brain that allow awareness, a person’s level of consciousness can change in several ways. Altered level of consciousness (ALC) is among the most common problems seen in medicine. Studies estimate that up to 5% of emergency room admissions in urban hospitals are related to disorders of consciousness.
Consciousness can be measured on a spectrum that ranges from full wakefulness to deep coma.
Altered levels of consciousness include the following conditions:
Causes
Trauma to the brain can cause impaired consciousness. Traumatic brain injury (TBI) is the leading cause of death and disability in young adults in the U.S. Several types of head trauma may cause TBI. For example, a closed head injury—the most common TBI—can result if the head rapidly accelerates or decelerates, causing the brain to move through the fluid in the skull and strike the inside of the skull. Other causes include direct impact on the head or penetration by a foreign object such as a bullet.
Infections are a common cause of impaired consciousness. The inflammation that accompanies infection is responsible for ALC. Encephalitis and meningitis are two nervous system-specific infections that can cause ALC.
Defects in the metabolic system can lead to waste build-up that can cause altered levels of consciousness (ALC). As the body goes about the normal processes needed to keep us alive, chemicals and other by-products are produced. In most cases, byproducts get into the bloodstream and are filtered by the liver, kidneys, and other organs. If one of these systems fails, waste products can build-up and act as a poison that interferes with the brain’s ability to function. The insulin/sugar imbalance of diabetes, for example, is a major metabolic problem that can cause impaired consciousness. Diabetics with low blood insulin levels produce ketones, a toxic by-product of fat metabolism. Conversely, when there is too much insulin, cells begin to starve to death. Either case can result in ALC.
Drug exposure is a common cause for ALC. Drug-induced ALC can result from an overdose of either over-the-counter or illegal drugs. Alcohol intoxication is probably the most common cause of drug-induced ALC. Similarly, exposure to certain readily available home or industrial chemicals can lead to changes in consciousness or even to death.
Structural abnormalities of the brain can lead to ALC Figure 01. Tumors (benign or cancerous) can form and crowd out the normal structures of the brain. As a result, weakness in the walls of the blood vessels in the brain (aneurysms) may begin to swell, or may even break, causing blood to pool inside the head and push the brain against the bony wall of the skull. The resulting damage can then cause ALC.
Figure 01. MRI Scan Showing a Brain Tumor
Symptoms
The symptoms of ALC are varied. Initial signs of ALC can be as subtle as slurring words while talking, or as severe as death. ALC can present as any of the levels of consciousness, from confusion to stupor to coma.
Symptoms accompanying ALC provide clues to the underlying cause Table 01. For example, if a person with ALC also has a tongue that is bitten or scarred, a doctor would suspect that epilepsy is the underlying cause. Likewise, if the person with ALC also has neck stiffness, the doctor may suspect that meningitis is the cause.
Table 1. Possible Causes of ALC by Accompanying Symptom or Sign
| System or region | Symptom | Possible cause(s) |
|---|---|---|
| Vital signs | Hypertension | Cerebral hemorrhage, hypertensive encephalopathy, increased intracranial pressure, renal or endocrine disorder |
| Hypotension | Ethanol or sedative drug toxicity, blood loss, diabetic coma | |
| Hyperthermia | Systemic infection, heat stroke, withdrawal from alcohol or drugs | |
| Hypothermia | Ethanol or barbiturate toxicity, shock, extracellular fluid deficit | |
| Bradycardia | Heart block, Stokes-Adams syndrome, increased intracranial pressure, hypothyroidism | |
| Tachycardia | Arrhythmia associated hypoxemia; atrial fibrillation associated with cerebral embolism | |
| Breath | Peculiar odor | Alcohol ingestion, hepatic failure, ketoacidosis, or uremia |
| Skin | Jaundice | Hepatic disorder |
| Needle-tracks | Drug overdose | |
| Rashes | Infectious disease, drug reaction, autoimmune disease, pellagra, thrombotic thrombocytopenic purpura | |
| Pallor | Hemorrhage (internal or external) | |
| Head | Localized tenderness, hematoma, crepitus | Skull fracture |
| Hemorrhage from ears or nostrils; hematoma, tenderness, or crepitus over mastoid process | Basilar skull fracture | |
| Face and conjunctiva hyperemic | Alcohol intoxication | |
| Tongue bitten or scarred | Epilepsy | |
| Neck | Stiffness | Suggests meningitis/encephalitis, trauma, or subarachnoid hemorrhage |
Risk Factors
Certain causes of ALC are more common in particular groups of individuals. Traumatic brain injury is the leading cause of death and disability in those under 45 years of age, while metabolic problems, which can also cause ALC, occur most often in middle-aged and older people.
Diagnosis
When something interferes with interactions in the brain that allow awareness, a person’s level of consciousness can change in several ways. Altered level of consciousness (ALC) is among the most common problems seen in medicine. Studies estimate that up to 5% of emergency room admissions in urban hospitals are related to disorders of consciousness.
Consciousness can be measured on a spectrum that ranges from full wakefulness to deep coma.
Altered levels of consciousness include the following conditions:
Trauma to the brain can cause impaired consciousness. Traumatic brain injury (TBI) is the leading cause of death and disability in young adults in the U.S. Several types of head trauma may cause TBI. For example, a closed head injury—the most common TBI—can result if the head rapidly accelerates or decelerates, causing the brain to move through the fluid in the skull and strike the inside of the skull. Other causes include direct impact on the head or penetration by a foreign object such as a bullet.
Infections are a common cause of impaired consciousness. The inflammation that accompanies infection is responsible for ALC. Encephalitis and meningitis are two nervous system-specific infections that can cause ALC.
Defects in the metabolic system can lead to waste build-up that can cause altered levels of consciousness (ALC). As the body goes about the normal processes needed to keep us alive, chemicals and other by-products are produced. In most cases, byproducts get into the bloodstream and are filtered by the liver, kidneys, and other organs. If one of these systems fails, waste products can build-up and act as a poison that interferes with the brain’s ability to function. The insulin/sugar imbalance of diabetes, for example, is a major metabolic problem that can cause impaired consciousness. Diabetics with low blood insulin levels produce ketones, a toxic by-product of fat metabolism. Conversely, when there is too much insulin, cells begin to starve to death. Either case can result in ALC.
Drug exposure is a common cause for ALC. Drug-induced ALC can result from an overdose of either over-the-counter or illegal drugs. Alcohol intoxication is probably the most common cause of drug-induced ALC. Similarly, exposure to certain readily available home or industrial chemicals can lead to changes in consciousness or even to death.
Structural abnormalities of the brain can lead to ALC Figure 01. Tumors (benign or cancerous) can form and crowd out the normal structures of the brain. As a result, weakness in the walls of the blood vessels in the brain (aneurysms) may begin to swell, or may even break, causing blood to pool inside the head and push the brain against the bony wall of the skull. The resulting damage can then cause ALC.Figure 01. MRI Scan Showing a Brain Tumor
The symptoms of ALC are varied. Initial signs of ALC can be as subtle as slurring words while talking, or as severe as death. ALC can present as any of the levels of consciousness, from confusion to stupor to coma.
Symptoms accompanying ALC provide clues to the underlying cause Table 01. For example, if a person with ALC also has a tongue that is bitten or scarred, a doctor would suspect that epilepsy is the underlying cause. Likewise, if the person with ALC also has neck stiffness, the doctor may suspect that meningitis is the cause.
Table 1. Possible Causes of ALC by Accompanying Symptom or Sign
| System or region | Symptom | Possible cause(s) |
|---|---|---|
| Vital signs | Hypertension | Cerebral hemorrhage, hypertensive encephalopathy, increased intracranial pressure, renal or endocrine disorder |
| Hypotension | Ethanol or sedative drug toxicity, blood loss, diabetic coma | |
| Hyperthermia | Systemic infection, heat stroke, withdrawal from alcohol or drugs | |
| Hypothermia | Ethanol or barbiturate toxicity, shock, extracellular fluid deficit | |
| Bradycardia | Heart block, Stokes-Adams syndrome, increased intracranial pressure, hypothyroidism | |
| Tachycardia | Arrhythmia associated hypoxemia; atrial fibrillation associated with cerebral embolism | |
| Breath | Peculiar odor | Alcohol ingestion, hepatic failure, ketoacidosis, or uremia |
| Skin | Jaundice | Hepatic disorder |
| Needle-tracks | Drug overdose | |
| Rashes | Infectious disease, drug reaction, autoimmune disease, pellagra, thrombotic thrombocytopenic purpura | |
| Pallor | Hemorrhage (internal or external) | |
| Head | Localized tenderness, hematoma, crepitus | Skull fracture |
| Hemorrhage from ears or nostrils; hematoma, tenderness, or crepitus over mastoid process | Basilar skull fracture | |
| Face and conjunctiva hyperemic | Alcohol intoxication | |
| Tongue bitten or scarred | Epilepsy | |
| Neck | Stiffness | Suggests meningitis/encephalitis, trauma, or subarachnoid hemorrhage |
Certain causes of ALC are more common in particular groups of individuals. Traumatic brain injury is the leading cause of death and disability in those under 45 years of age, while metabolic problems, which can also cause ALC, occur most often in middle-aged and older people.
As most people with ALC are incapable of providing information about their own condition, information from family, friends, and bystanders is very valuable for doctors trying to make a diagnosis. If you witness someone suffering from ALC, you should go to the hospital with the person to provide information to the doctors. Similarly, make sure that any bottles of chemicals or other substances that the person may have ingested are taken to the hospital.
The doctor will ask a family member or a witness about what happened before the ALC occurred, and will also ask about any other illnesses or allergies the person may have. If you were a witness to someone experiencing ALC, the doctor would want you to describe what the person was doing before calling for help. For example, was the person staggering, talking incoherently, or did they pass out? Was the person working with an insecticide, did they have the car running in an enclosed area? The doctor may also ask about family history of diseases that could cause ALC, orabout any possible allergies the person may have.
After the history, the doctor will perform a quick physical and neurological exam. Since the brain also controls heart rate and rhythm, breathing characteristics, blood pressure, and body temperature, the doctor will check these vital signs for clues about the origin of ALC. The doctor will also evaluate level of consciousness by asking the person to recite their own name, and then assessing how well they are oriented to time and place. The doctor will then shine a light into the person’s eyes to see if both of the pupils get smaller, and will test whether the person has control over the muscles of the eyes by having them follow an objector finger around their field of vision. An EEG may also be run to check for the condition nonconvulsive status epilepticus (NSE) as a cause of coma.
Laboratory tests on the blood and other body fluids help the doctor make a diagnosis. Blood tests can help rule out metabolic reasons for ALC such as diabetes or kidney failure. Blood and urine tests can also be used to detect levels of medication or drug overdose.
The doctor may perform radiologic tests to help diagnose physical causes of ALC. Skull x-rays and computed tomography (CT) scans can detect fractures, tumors, and abnormal blood vessels. CT scans are also useful when bruising or inflammation are suspected. Cerebral angiography uses a special dye to highlight the blood vessels in the brain to see where they might be narrowed or obstructed. Magnetic resonance imaging (MRI) studies may be used to get a better view of the soft tissue—for example, when a stroke or an aneurysm might be the cause of concern. The MRI also is less affected by bones, and can get specific views of the brain that aren’t available using conventional x-rays. If the cause of ALC remains unknown after these tests, the doctor may order a chest radiograph to determine if cardiac or pulmonary disease is the culprit. If the doctor suspects meningitis, and the CT scan is normal, he or she will perform a spinal tap, looking for laboratory evidence of infection. This procedure involves putting a needle into the spinal cord.
Take precautions while driving or engaging in activities where head injuries might be possible. Wear helmets and other protective gear when engaging in contact sports, skateboarding, riding a bicycle or motorcycle, or participating in other forms of recreation where head injuries might be possible. Wear appropriate protective gear if required at your job. You should also wear a seatbelt when in a car to avoid head injuries from an accident.
Drink alcohol in moderation. Alcohol dulls your reflexes and decreases judgment, increasing the likelihood that you will get in an accident that could cause a head injury. Therefore, if you drink, do so in moderation, and do not attempt to drive or take part in other activities that require attention.
If you are diabetic, maintain appropriate blood sugar levels. Excessively high or low blood sugar levels can lead to ALC. Therefore, be sure to monitor your blood sugar levels closely if you are diabetic.
Take precautions to avoid stroke, which can cause ALC. You can reduce your risk for ALC-causing stroke by controlling high blood pressure, treating heart rhythm problems, watching for and treating cholesterol problems, and quitting smoking.
Get the Haemophilus vaccine (HiB vaccine) to prevent a type of meningitis. As ALC can be triggered by meningitis and other infections, get the HiB vaccine to protect yourself against a certain strain of the infection. Teenagers are also advised to get an additional vaccine, Menactra, to prevent meningitis cause by a different bacteria.
Prevention and Screening
Take precautions while driving or engaging in activities where head injuries might be possible. Wear helmets and other protective gear when engaging in contact sports, skateboarding, riding a bicycle or motorcycle, or participating in other forms of recreation where head injuries might be possible. Wear appropriate protective gear if required at your job. You should also wear a seatbelt when in a car to avoid head injuries from an accident.
Drink alcohol in moderation. Alcohol dulls your reflexes and decreases judgment, increasing the likelihood that you will get in an accident that could cause a head injury. Therefore, if you drink, do so in moderation, and do not attempt to drive or take part in other activities that require attention.
If you are diabetic, maintain appropriate blood sugar levels. Excessively high or low blood sugar levels can lead to ALC. Therefore, be sure to monitor your blood sugar levels closely if you are diabetic.
Take precautions to avoid stroke, which can cause ALC. You can reduce your risk for ALC-causing stroke by controlling high blood pressure, treating heart rhythm problems, watching for and treating cholesterol problems, and quitting smoking.
Get the Haemophilus vaccine (HiB vaccine) to prevent a type of meningitis. As ALC can be triggered by meningitis and other infections, get the HiB vaccine to protect yourself against a certain strain of the infection. Teenagers are also advised to get an additional vaccine, Menactra, to prevent meningitis cause by a different bacteria.
Treatment
ALC is a medical emergency. As there is usually nothing an onlooker can do to treat the cause, the best advice is to call 911 and get the person to the hospital as soon as possible. It should be remembered, however, that even minor changes such as slurring words or unsteadiness could be an early sign of impending problems that should beinvestigated. Do not wait for the person to “pass out” before seeking medicalcare.
After contacting the ambulance, there are some things that can be done to help keep the person safe until help arrives. For example, if the person does not respond when you shake them or yell their name, check to make sure they are still breathing, and that they have a pulse. If they do not, begin cardiopulmonary resuscitation (CPR).If you do not know CPR, an ambulance dispatcher can talk you through the procedure over the telephone. If heat stroke is a possibility, get the person into the shade or an air-conditioned area immediately. If there is ice available (or even cold soft drink cans), place it in the groin area and under the neck. If you know that the probable cause of ALC is type II diabetes, provide the person with sugar as soon as possible. The best way to provide this sugar is through a paste that can be applied to the gums (called Glucagon, among other things). If this paste is not available, regular table sugar can also be placed under the lips and against the gums. The blood vessels in this area are very close to the surface, and readily absorb the sugar, getting it into the blood system and to the brain very quickly. If the person is having a seizure, do not touch them unless it is absolutely necessary to help them avoid injury. If possible, open their collar, remove ties or other constricting things from around the neck and unbutton their shirt. Never try to force anything into the mouth. Remove from the area any objects such as chairs or tables that the person might strike, thereby further injuring themselves. Do not attempt to restrain the person in any way. When the seizure has stopped, place the person on their side in the recovery position. Look around the area for any pill or chemical containers.This will give the healthcare team valuable clues about overdose, poisoning, or medication interaction as cause for the ALC.
Self care measures for ALC are general, and consist mainly of ways to prevent the various causes of ALC. Carefully following the treatment regimens for diseases such as diabetes, maintaining and using safety equipment, watching your diet for too much cholesterol, and lowering your blood pressure if needed are all ways to care for yourself and prevent various possible causes of ALC.
Your doctor is the best source of information on the drug treatment choices available to you.
Other therapies available for treating ALC are specific to the underlying condition.
Surgery is used to relieve pressure in the brain from a developing mass. A growing mass, which can take many forms (i.e., bleeding from a stroke or aneurysm, abscess from an infection, a tumor or swelling related to trauma), can press on the brain and cause ALC. If this is the case, your doctor will order surgery to remove the offending mass.
If surgery is necessary, a craniotomy will most likely be done. A craniotomy is a surgical method of cutting open the skull to gain access to the brain. After anesthesia is given and the patient is asleep, the surgeon will cut a flap in the skin to expose the bone of the skull. They will then usually drill a number of holes is the skull and use a specialized saw to connect them. The bone flap is then removed, exposing the brain. What happens next will depend on the underlying cause of ALC. If it is an aneurysm, then it may either be clipped, or a special reinforcing fabric will be placed around it to keep it from getting bigger. If the cause is bleeding into the brain or abscess, the surgical team will remove it from the area. In other cases, a tumor may be removed.
Following surgery, the patient is usually admitted to an intensive care unit where vital signs and pressure inside the skull can beclosely monitored. Medications are usually given to limit the chance for infection and seizures after surgery. The person will also be watched closely for changes in level of consciousness and weakness or loss of speech that often signal problems. Frequently the person will only stay in the ICU for about 24 hours. Depending on the outcome, the person may be released home or sent to are habilitation hospital for further treatment.
The prognosis for ALC varies widely depending on the cause.
Follow-up depends on the type of illness and the severity of ALC.