| Head injury | |
|---|---|
| Classification and external resources | |
| ICD-10 | S00.0S09 |
| ICD-9 | 800-879 |
| eMedicine | neuro/153 |
| MeSH | D006259 |
Head injury refers to trauma of the head. This may or may not include injury to the brain.[1] However, the terms traumatic brain injury and head injury are often used interchangeably in medical literature.[2]
The incidence (number of new cases) of head injury is 300 of every 100,000 per year (0.3% of the population), with a mortality rate of 25 per 100,000 in North America and 9 per 100,000 in Britain. Head trauma is a common cause of childhood hospitalization.
Contents |
Head injuries include both injuries to the brain and those to other parts of the head, such as the scalp and skull.
Head injuries may be closed or open. A closed (non-missile) head injury is where the dura mater remains intact. The skull can be fractured, but not necessarily. A penetrating head injury occurs when an object pierces the skull and breaches the dura mater. Brain injuries may be diffuse, occurring over a wide area, or focal, located in a small, specific area.
A head injury may cause a minor headache skull fracture, which may or may not be associated with injury to the brain. Some patients may have linear or depressed skull fractures.
If intracranial hemorrhage occurs, a hematoma within the skull can put pressure on the brain. Types of intracranial hemorrage include subdural, subarachnoid, extradural, and intraparenchymal hematoma. Craniotomy surgeries are used in these cases to lessen the pressure by draining off blood.
Brain injury can be at the site of impact, but can also be at the opposite side of the skull due to a contrecoup effect (the impact to the head can cause the brain to move within the skull, causing the brain to impact the interior of the skull opposite the head-impact).
If the impact causes the head to move, the injury may be worsened, because the brain may ricochet inside the skull causing additional impacts, or the brain may stay relatively still (due to inertia) but be hit by the moving skull (both are contrecoup injuries).
Specific problems after head injury can include:
Mild concussions are associated with sequelae. Severity is measured using various concussion grading systems.
A slightly greater injury is associated with both anterograde and retrograde amnesia (inability to remember events before or after the injury). The amount of time that the amnesia is present correlates with the severity of the injury. In all cases the patients develop postconcussion syndrome, which includes memory problems, dizziness, tiredness, sickness and depression.
Cerebral concussion is the most common head injury seen in children.
Types of intracranial hemorrhage are roughly grouped into intra-axial and extra-axial. The hemorrhage is considered a focal brain injury; that is, it occurs in a localized spot rather than causing diffuse damage over a wider area.
Intra-axial hemorrhage is bleeding within the brain itself, or cerebral hemorrhage. This category includes intraparenchymal hemorrhage, or bleeding within the brain tissue, and intraventricular hemorrhage, bleeding within the brain's ventricles (particularly of premature infants). Intra-axial hemorrhages are more dangerous and harder to treat than extra-axial bleeds.[3]
| Hematoma type | Epidural | Subdural |
|---|---|---|
| Location | Between the skull and the dura | Between the dura and the arachnoid |
| Involved vessel | Temperoparietal locus (most likely) - Middle meningeal artery Frontal locus - anterior ethmoidal artery Occipital locus - transverse or sigmoid sinuses Vertex locus - superior sagittal sinus |
Bridging veins |
| Symptoms | Lucid interval followed by unconsciousness | Gradually increasing headache and confusion |
| CT appearance | Biconvex lens | Crescent-shaped |
Extra-axial hemorrhage, bleeding that occurs within the skull but outside of the brain tissue, falls into three subtypes:
Cerebral contusion is bruising of the brain tissue. The majority of contusions occur in the frontal and temporal lobes. Complications may include cerebral edema and transtentorial herniation. The goal of treatment should be to treat the increased intracranial pressure. The prognosis is guarded.
Diffuse axonal injury, or DAI, usually occurs as the result of an acceleration or deceleration motion, not necessarily an impact. Axons are stretched and damaged when parts of the brain of differing density slide over one another. Prognoses vary widely depending on the extent of damage.
Presentation varies according to the injury. Some patients with head trauma stabilize and other patients deteriorate. A patient may present with or without neurologic deficit.
Patients with concussion may have a history of seconds to minutes unconsciousness, then normal arousal. Disturbance of vision and equilibrium may also occur.
Common symptoms of head injury include coma, confusion, drowsiness, personality change, seizures, nausea and vomiting, headache and a lucid interval, during which a patient appears conscious only to deteriorate later.[4]
Symptoms of skull fracture can include:
Because brain injuries can be life threatening, even people with apparently slight injuries, with no noticeable signs or complaints, require close observation. The caretakers of those patients with mild trauma who are released from the hospital are frequently advised to rouse the patient several times during the next 12 to 24 hours to assess for worsening symptoms.
The Glasgow Coma Scale is a tool for measuring degree of unconsciousness and is thus a useful tool for determining severity of injury. The Pediatric Glasgow Coma Scale is used in young children.
Common causes of head injury are motor vehicle traffic collisions, home and occupational accidents, falls, and assaults. Bicycle accidents are also a cause of head injury-related death and disability, especially among children. Wilsons disease has also been indicative of head injury. [5]
The need for imaging in patients who have suffered a minor head injury is debated. A non-contrast CT of the head should be performed immediately in all those who have suffered a moderate or severe head injury,an MRI is also an option.[6]http://www.jpmsonline.com/jpms-vol1-issue3-pages78-82-oa.html
Most head injuries are of a benign nature and require no treatment beyond analgesics and close monitoring for potential complications such as intracranial bleeding. If the brain has been severely damaged by trauma, neurosurgical evaluation may be useful. Treatments may involve controlling elevated intracranial pressure. This can include sedation, paralytics, cerebrospinal fluid diversion. Second line alternatives include decompressive craniectomy (Jagannathan et al. found a net 65% favorable outcomes rate in pediatric patients), barbiturate coma, hypertonic saline and hypothermia. Although all of these methods have potential benefits, there has been no randomized study that has shown unequivocal benefit.
In children with uncomplicated minor head injuries the risk of intra cranial bleeding over the next year is rare at 2 cases per 1 million.[7]
In some cases transient neurological disturbances may occur, lasting minutes to hours. Malignant post traumatic cerebral swelling can develop unexpectedly in stable patients after an injury, as can post traumatic seizures. Recovery in children with neurologic deficits will vary. Children with neurologic deficits who improve daily are more likely to recover, while those who are vegetative for months are less likely to improve. Most patients without deficits have full recovery. However, persons who sustain head trauma resulting in unconsciousness for an hour or more have twice the risk of developing Alzheimer's disease later in life.[8]
Head injury may be associated with a neck injury. Bruises on the back or neck, neck pain, or pain radiating to the arms are signs of cervical spine injury and merit spinal immobilization via application of a cervical collar and possibly a long board.
If the neurological exam is normal this is reassuring. Reassessment is needed if there is a worsening headache, seizure, one sided weakness, or has persistent vomiting.
|
||||||||||||||||||||||||||