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Abstract
Minor closed head injury is a common problem, affecting over two million Americans. We review some of the general principles in the evaluation of head injuries in both children and adults. We discuss some of the high risk clinical factors from the history and physical examination that indicate a need for computed tomography in the adult, including a Glasgow Coma Scale of less than fifteen when measured two hours after the injury, vomiting more than twice, a suspected skull fracture, use of coumadin or other blood thinner, other concomitant diseases that predispose to bleeding such as hemophilia or thrombocytopenia, age greater than 65, or the presence of a focal neurologic deficit. High risk factors in children include age less than three months, suspicion of a skull fracture, focal neurologic deficits, bulging fontanelle, inconsolability, loss of consciousness for more than a minute, seizure, or vomiting more than four times. Sports related concussions are also reviewed, and specific guidelines are presented to help the clinician determine when sports related activities might safely be resumed. Prognostic factors that increase the probability of increased intracranial pressure are outlined. Finally, a brief overview of current treatment modalities is presented.
Head Injury In The Adult
There are over two million cases of closed head injury per year in the United States.1 Our colleagues in Canada have researched the acute evaluation of head injuries in adults and much of the discussion below is based on the head injury protocols they have developed.2
First let me state that there is probably little reason to get routine x-rays of the head.3 The advent of computed tomography (CT) scans has pretty much replaced the use of regular x-rays for head trauma when CT is available. CT's yield far more information, and enable a look into the brain to see if there is any bleeding or other injury. Since they also show the cranial bones well (except the base of the skull), regular x-rays are rarely used for head trauma. CT's do not show the base of the brain that well, so in selected cases MRI may be utilized. The gold standard for the evaluation of acute traumatic head injury is still the head CT.
The first step in the evaluation of a patient with closed head injury is to insure a reliable history and physical exam can be obtained. Therefore, the patient should not be intoxicated, their baseline mental status should be noted (the history and possibly the physical exam may be unreliable in the demented patient) and the patient should be able to communicate with the examining physician (language barriers or other limitations to communication will also limit the reliability of the history and physical exam). If one or more of these limiting factors exist, an immediate head CT evaluation should be considered. The next step is a detailed history of what occurred and a thorough physical exam. The Glasgow Coma Scale (GCS as reviewed in table 1) is a quantified way to evaluate patients after head injury. It has been shown to be a reliable tool with reasonably reproducible evaluations even from different examining physicians. Using the history and physical exam, as well as the calculated GCS, patients may be risk stratified.2
High risk patients have a Glasgow Coma Scale less than 15 when calculated two hours after the injury, have vomited more than twice, have a suspected (based on clinical exam) open, depressed or basilar skull fracture, are on a blood thinner like coumadin or have other reasons to bleed easily (hemophilia or severe thrombocytopenia for example), or are over 65 years of age. Any patient with a new focal neurological deficit is also considered high risk.
Intermediate risk patients have retrograde amnesia for greater than 30 minutes prior to the injury or have a mechanism of injury which is especially concerning, such as one that has caused other serious morbidity or a fall onto the head from more than three feet or down more than 5 stairs.2,4,5
Patients with a less concerning mechanism of injury (falls less than 3 feet or down less than 5 stairs) without any of these problems are considered low risk.
All high-risk patients and most with medium risk should be evaluated with a head CT. The results of the head CT will aid in giving quantitative risk stratification for the possibility of increased intracranial pressure as will be discussed in more detail below.2,4,5
Head Injury In The Child
Almost 600,000 children have some type of traumatic brain injury per year. Many of these injuries occur as part of a multiple trauma injury (such as a motor vehicle accident), but many are isolated head injuries from falls or other accidents. The American Academy of Pediatrics has formulated a prac- tice guideline recommendation to deal with cases of closed head injury in children, and the discussion that follows is based on those recommendations.6,7
As was the case with adults, there is probably little reason to get regular x-rays of the head when head CT is available. As in adults, the gold standard for evaluation of acute traumatic head injury in children is the head CT. In very young children it can be tricky to obtain the head CT and some children will require sedation for this. This adds an extra level of complexity in children, since the risks and benefits of sedation versus obtaining the head CT need to be carefully weighed.
The clinical factors we need to evaluate in children are similar to those in adults. First we need to know we can get a reliable history and physical exam. Older children can usually supply a good history of what happened on their own, but for younger children the caregiver will need to be able to tell us what happened. Even if the actual fall is not observed, many caregivers 'hear the thump' of when the child falls and can give details about where the child fell from and what happened immediately after the fall.
The clinical data we need to collect in children is very similar to that obtained in the history and physical exam of the adult, modified to be appropriate for the child. How far was the fall? Did the child cry right away? Were they consolable? Was there a loss of consciousness? Did they vomit? Are they behaving normally now? Do they have any other medical problems, including bleeding problems like hemophilia? For all children with head injury (as with any injury in a child) child abuse must always be considered.
High-risk children include those less than three months old, any child where there is clinical suspicion of skull fracture, any child with altered mental status (for their age), any focal neurological changes, bulging fontanelle or irritability that persists (the inconsolable child). Other indicators of high-risk head injury in children are loss of consciousness for more than a minute, more than four episodes of vomiting after the head injury or a seizure after the head injury.6,7
Intermediate risk children include those with 3-4 episodes of vomiting, transient (less than a minute) duration of loss of consciousness, irritability that resolves, slight change in behavior ('crankier than normal' for example) or a skull fracture that is more than 24 hours old.6,7
Low risk children are those without any of the criteria noted above who appear clinically well. In children with low risk head injuries with no loss of consciousness, no vomiting, no headache (other than that expected from the local bruise), a normal exam and a mechanism of injury that is not overly concerning (a fall onto their head roughly less than their height or three feet, whichever is less), close observation at home by a competent caregiver is usually all that is needed.6,7
All children with high-risk head injuries should be evaluated with a head CT. The situation is not as clear-cut for intermediate risk injuries. The decision to get a head CT versus close observation will need to be made for each individual patient based on the physician's clinical judgment. In small children where sedation would be necessary to get a head CT, many practitioners will lean toward observation over CT scan.6
Head Injury During Sports
are 300,000 sports-related brain injuries per year in the United States. The discussion that follows is based on recommendations from the Family Practice Notebook8 (which made these recommendations based on literature from the journals Neurology, Pediatrics, Physician Sports Medicine and American Family Physician).9-12 For this discussion we will define a concussion as a trauma induced transient loss of normal mental function that lasts less than 24 hours. It can include loss of consciousness, but this is not required for the diagnosis of concussion.
Thankfully, most sports-related concussions are mild and the patient has no long lasting sequelae, but there has been a growing concern for young athletes that suffer repeated concussions. Several recent studies have suggested long term decreases in intellectual and cognitive skills in athletes who suffer repeated concussions (even mild concussions).
One of the 'grading' systems that have been developed to scale levels of concussion will be discussed here. Although concussions really lie on a continuous curve based on the occurrences and symptoms for the individual patient rather than at discreet levels, this grading system allows easier recommendations for treatment and care.
Grade 1 concussion has a brief (less than 15 minutes) trauma induced alteration in mental status (see Table 2 for examples) with no loss of consciousness.8-12 Grade 2 again has no loss of consciousness, but has the symptoms last longer than 15 minutes.8-12 Grade 3 has some loss of consciousness involved.8-12 If the loss of consciousness is more than a few minutes the patient should be immediately brought to the emergency department to be evaluated. The recommendations for athletes that have suffered a concussion depend on the grade of concussion.
For Grade 1 concussion removal from the sports activity and careful observation for 15 minutes is all that is required. If the athlete's symptoms completely resolve they can return to the activity after this period of observation. Any athlete who has had two Grade 1 concussions should be removed from the activity (whether it occurs that same day or at a later date). They will need to be examined by a physician and should not return to sports until symptoms have been resolved for at least one week. A third Grade 1 concussion requires removal from sports for the entire season and re-examination by a physician.8-12
An athlete suffering a Grade 2 concussion should be removed from the sports activity and carefully observed. They will need to be examined by a physician and should not return to sports until symptoms have been resolved for at least one week. A second Grade 2 concussion (or a Grade 1 concussion following a previous Grade 2 concussion) requires re-evaluation by a physician and at least a month off after symptoms have totally resolved. A third Grade 2 concussion requires removal from sports for the entire season and re-examination by a physician.8-12
Any athlete whose symptoms progress during the time they are observed on the 'sidelines' for Grade 1 or 2 concussions, or whose symptoms fail to show some improvement during the 15 minute observation period (and then resolve within the next 15 minutes or so), requires immediate evaluation in the emergency department.8-12
Any athlete suffering a Grade 3 concussion should be removed from the activity and will need immediate evaluation in the emergency department. This is also true of any athlete with neck pain accompanying the head injury (if there is any concern of neck injury the athlete should have their neck immobilized immediately), or if the athlete has any focal neurological changes, vomits twice or more, has a seizure or has any symptoms that do not show improvement in the 15 minute observation recommended for the Grade 1 and 2 concussions noted above. As noted in the previous discussions, some of these patients will need a head CT. Athletes who have suffered a Grade 3 concussion should be symptom free at least one month prior to returning to any sports activity. A second Grade 3 concussion should again get evaluation in the emergency department and the sports season will need to be terminated. A third Grade 3 concussion again needs evaluation in the emergency department, and the sport (and other high risk sports) should be terminated completely.
Prognosis of Closed Head Injury
One of the most pressing concerns in patients with closed head injury is identifying those at risk for increased intracranial pressure from any associated traumatic brain injury and then avoiding the subsequent severe consequences. The predictive value of the evaluations recommended above will help identify patients at risk for increased ICP and is discussed below. Much of this discussion is based on literature from the Brain Trauma Foundation and from work supported by the British Trauma Society and the International Trauma Anesthesia and Critical Care Society (ITACCS)13-21.
The volume of the intracranial space is a constant for patients once the fontanels have closed. Even for infants whose fontanels are open, the overall potential compensatory volume possible to accommodate bleeding or swelling is limited. In the early 19th century Monro-Kellie proposed a model of the head as:
Intracranial volume = brain volume + CSF volume + blood volume + mass (lesion, bleeding, etc.) volume.
Cerebral spinal fluid (CSF) volume may decrease as a compensatory mechanism for increased volume from a mass lesion, but once a critical value for the volume of the mass lesion has been reached, intracranial pressure (ICP) rises exponentially. A catastrophic consequence of this increase in intracranial pressure can be brain herniation and death.
Normal ICP is 0-10 mmHg. Although there is no absolute number for which treatment for increased intracranial pressure should be initiated, 20 mmHg is used by many authors. Table 3 summarizes approximate risks for increased intracranial pressure based on factors noted in the discussion above.
Noting the relative risk for increased intracranial pressure in Table 3 can help guide possible therapeutic decisions. Patients at high risk for increased intracranial pressure will need to be admitted to an intensive care facility with the capability to monitor ICP.
Treatment Options For Patients With Increased ICP
The first step in treatment for closed head injury is to insure adequate oxygenation and to maximize cerebral perfusion. Cerebral perfusion pressure (CPP) can be calculated from the mean arterial pressure (MAP) by:
For a given MAP this relationship illustrates why preventing increased ICP is so important. It also illustrates why maintaining MAP (usually in the range of 100-110 mmHg) is so fundamental. The usual ABC's of resuscitation apply for head injury. Insuring good oxygenation requires a patent airway and adequate respiratory effort or assistance of respirations, as well as support of blood pressure where indicated.
Treatment for increased ICP will need to be decided on a case-by-case basis, and usually in consultation with a neurosurgeon. Where suspicion of increased ICP is high, either based on initial clinical indicators as outlined above or based on observed deterioration of the patient's clinical status, initial interventions should include elevation of the head to 30-40 degrees, minimizing stimuli (such as suctioning the airway), and keeping fluids at roughly half to 2/3 of maintenance. If immediate monitoring of ICP is not possible, empiric mannitol therapy should also be considered.13
Mannitol (and other diuretics) has been shown to be effective in reducing ICP. Serum osmolalities greater than 320 mOSsm/L should be avoided, as should hypovolemia or adverse affects on MAP. There is data showing improved clinical outcomes in patients with increased ICP treated with mannitol, and hence it is a commonly used and recommended intervention.13 There is also some data that indicates that bolus therapy might be preferable to continuous infusions.
There has been a lot of attention given to rapid sequence intubation (RSI) for patients requiring intubation who have suffered closed head injury. Lidocaine is often recommended to decrease transient rises in ICP in response to laryngeal stimulation, although a recent review article22 notes that there is no definitive evidence of its effectiveness. Since several authors still recommend it, and it has not been shown to have any deleterious effects, pretreatment with lidocaine is still a reasonable option. Narcotic agents are also often recommended as pretreatment during a RSI protocol to avoid increases in ICP from a pain response and possibly for vasodilatory affects. Most of the sedating agents (for example benzodiazepines, etomidate or sodium thiopental) commonly used for RSI are known to decrease ICP (except ketamine which raises ICP and should be avoided in head injury patients) and no study to date has shown preference of one agent over another. Succinylcholine is known to cause fasciculations in patients, which may also cause transient rises in ICP, and so many authors recommend a defasciculating dose of a paralytic agent as part of a RSI protocol for head injury patients prior to intubation.13
Many other therapeutic interventions for ICP have been considered in the past, but are no longer recommended. At present, hyperventilation is NOT considered appropriate, since it has been shown to decrease cerebral perfusion. Mild hyperventilation to CO2 around 30-35 is still recommended by some authors.13 Steroids have been considered in the past for increased ICP but have not been shown to improve outcomes, and so are not routinely recommended. However, selected patients with tumors or other mass lesions with significant cerebral edema might still benefit from steroid therapy. Empiric seizure prophylaxis is also recommended by some authors to avoid increases in ICP in patients who may seize.13
Some early research has shown that treatment with indomethacin can decrease ICP, however there is at present no clinical evidence of improved outcomes with this treatment and until more research can be done no recommendations for its use can be made. Other possible therapeutic interventions include hypothermic treatment, barbiturate coma and mild sustained hyperventilation. These last options would only be considered in consultation with a neurosurgeon in appropriate monitored settings.13
Summary
Head injury is a common occurrence and will frequently be seen by physicians in a variety of settings including office visits, emergency departments and in the field. Recommendations for evaluations of patients for particular clinical scenarios are outlined above. These recommendations are guidelines to be used in conjunction with the physician's clinical judgment to help decide appropriate testing for a given patient. Results of these evaluations may also yield prognostic information that will also help guide treatment.
There is lots of ongoing research into possible therapeutic interventions to improve outcome in severely injured closed head trauma patients. Firm recommendations can be made at this time for treatment with mannitol for those patients with (or at high risk for) increased ICP. Other therapeutic options used in specialized centers include hypothermic treatments and barbiturate coma. Patients with significant traumatic brain injury will need to be managed with input from a qualified neurologist and/or neurosurgeon.
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