Head Injury 1

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Traumatic Brain Injury (Ⅰ ) Department of Neurosurgery,The First Affiliated Hospital of Zhengzhou University Xu Bin

HEAD ANATOMY

Skull Anatomy The skull is a rounded layer of bone designed to protect the brain from penetrating injuries.

Interior Skull Surface Bony ridges

The base of the skull is rough, with many bony protuberances.These ridges can result in injury to the temporal lobe of the brain during rapid acceleration.

Injury from contact with skull

Blood Vessels of the Skull

The brain requires a rich blood supply, and the space between the skull and cerebrum contains many blood vessels.These blood vessels can be ruptured during trauma, resulting in bleeding.

Groove for middle meningeal artery

The Meninges The meninges are layers of tissue that separate the skull and the brain. Skull Dura mater Arachnoid Layer Pia Mater Brain

Among central nervous system disorders,craniocerebral trauma is second only to stroke as a cause of death.Traumatic injury is the leading cause of death in persons below age 45 and head injury constitutes a major portion of deaths in this group.

Approximately 500,000 head injuries,accounting for the loss of 70,000 lives,occur each year in the USA.Craniocerebral trauma produces severe disability and imposes a huge financial and psychologic burden on the patient,the patients family and society.

Epidemiology of Head Injury ❧2,000 people /100,000/year attend hospital ❧300 of these will be admitted ❧Prevalence of significant disability estimated at 150/100,000

Every 21 Seconds One Person In The U.S. Sustains A Brain Injury

Epidemiology of Head Injury ❧Age: 15-25 years ❧Sex: M:F ~ 3:1 ❧Causes: Falls Road Traffic Accidents Assault Sports Work ❧Alcohol: ~ 50%

Overview ❧Head injury is a common traumatic disease in normal time. It has a high mortality rate. According to the anatomic position injured, head injury can be divided into three types. That is scalp injury, skull fracture and cerebral injury, which could happened separately or simultaneously.

The stereotactic phenomena explain the deep cerebral lesions.

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The stereotactic phenomena explains the importance of the contrecoup cerebral lesions.

❧Meninges ❧Bones ❧Scalp

Head injuries can range from a minor bump on the head to a devastating brain injury. Learning to recognize a serious head injury and implementing basic first aid can make the difference in saving someone's life. Common causes of head injury include traffic accidents, falls, physical assault and accidents at home, work, outdoors or while playing sports.

The brain is a soft organ which floats in fluid inside the skull. In an accident the brain can be damaged by bruising, tearing, shearing, shaking or twisting. Bleeding can occur in or around the brain.

The brain is divided into sections called lobes. The lobes carry out different functions around the body. Typically in a Traumatic Brain Injury (TBI) the frontal and temporal lobes are damaged. These lobes control functions which include learning, emotions, memory, and language. Every brain injury is very different, however, and no area of the brain is invulnerable.

Head injury can be classified as either closed or opening. opening The signs and symptoms of a head injury may occur immediately or develop slowly over several hours.

Closed Head Injury When a person receives an impact to the head from an outside force, but the skull does not fracture or displace this condition is termed a "closed head injury". In closed head injury, the head sustains a blunt force by striking against an object. Again, separate terminology is added to describe the brain injury. For example, a person may have a closed head injury with a severe traumatic brain injury.

Opened Head Injury If the force that hits a person's head is great enough, the skull can fracture or become out of place. When this happens, the person is described as having an "open head injury". This terminology is referring to the condition of the skull and not the brain. Separate terms are used to describe the condition of the brain. For example, a person may be described to have an open head injury with a severe traumatic brain injury.

In opening head injuries, a high velocity object breaks through the skull and enters the brain. When the head receives an impact from an outside source, if the brain is injured the brain may swell. If the skull is fractured or displaced, this can allow the brain room to swell and can assist in reducing the squeezing of brain tissues.

If the skull is fractured or displaced, bone fragments from the skull can enter the brain and cause further injury. Because the skull is damaged or open, it cannot protect the brain as it did before. The once protected brain is now exposed, which leaves it vulnerable to infections and further injury.

Persons with an open head injury may be assigned to wear a helmet to protect the exposed brain from impact and further injury.If a piece of the skull is displaced during traumatic injury, that piece of skull may be surgically replaced at a later date. An artificial skull piece may be applied also.

PATHOLOGY OF BRAIN INJURIES ❧Scalp injuries ❧Skull fracture ❧Cerebral concussion ❧Cerebral contusion ❧Diffuse Axonal Injury ❧Epidural hematoma ❧Subdural hematoma

SCALP This consists of five layers; the first three layers are bound together and moved as a unit. The layers are: A.Skin B.Subcutaneous tissue This is a fibro-fatty layer. The fibrous septa unite the skin to the underlying aponeurosis of the fronto- occipitalis muscle. The scalp Vessels lie within this layer.

C.Epicranial aponeurosis This is a thin fibrous sheath attached to the bellies of the Fronto-occipitalis muscle. Deep to it is the sub aponeurotic space. D.Loose areolar layer Occupying the sub aponeurotic space. This layer contains emissary veins. E.Pericranium Which is periosteum of the skull bone.

The scalp is very vascular and laceration can cause severe loss of blood. The vessels within the scalp do not constrict when injured because the wall is adherent to the surrounding fibre fatty tissue in the subcutaneous area. Bleeding can be controlled by applying pressure or suturing the scalp.

Scalp: Scalp lacerations are common and are important chiefly as sources of significant hemorrhage or infection.Thick scalp with its overlying hair provides a cushion for the skull and brain;blunt trauma commonly cause stellate burst lacerations.

Numerous arterial and venous anastomoses contribute to brisk bleeding but also to effective healing.Most of these vessels lie in the subcutaneous fat immediately superficial to the galea,the dense fibrous tissue that makes the scalp stiff and unyielding.

scalp injury ❧Hematoma of the scalp (1) Subcutaneous hematoma (2) Subgaleal hematoma (3) Subperiosteal hematoma ❧Laceration of scalp

Subcutaneous hematoma ❧hematoma lie in subcutaneous tissues layer. As there are much longitudinal fibrous tissues between skin and subcutaneous layer, the hematoma is not liable spreading. Clinical finding is a swelling limited.

Subgaleal hematoma ❧hematoma is located in subgaleal layer. Because this layer is rarefaction and has no separated tissues, the hematoma always spread to total head. Clinical finding is skull enlarged, swelling and fluctuation.

Subperiosteal hematoma ❧hematoma is located in subperiosteal layer. As periosteum is tight junction to bone in bone suture, the hematoma is limited in one cranium, and always goes along with bone fraction.

laceration of scalp ❧always wounded by sharp object, such as knife. If the galea aponeurotica break, the wound will be dehiscence like baby’s mouth, and have much more bleeding. Treatment: debridment and suture the whole layers

Treatment ❧Scalp hematoma can be absorbed by itself. If it is tremendous and can not be absorbed after 2 weeks, suction hematoma through puncture is necessary.

Fracture of the skull

Classification ❧(1) Classified by shape: ❧linear fracture ❧depressed fracture ❧Compound fracure ❧(2) Classified by site: ❧fracture of the vault of the skull ❧fracture of the base of the skull

Skull Fracture ❧Blunt trauma ❧Severe headache, nausea, deformity, “raccoon eyes”, bleeding/CSF (nose, ear) ❧Immobilize, EMS, monitor for complications (intracranial bleeding, infection)

fracture of anterior fossa: raccoon eyes

fracture of posterior fossa:Bell’s sign

Skull: A variety of skull injuries may follow blunt trauma: 1.Simple skull fracture-Linear non-displaced vault fractures are common and require no specific treatment but are important as markers of the significant force that was delivered to the head.The patient must be carefully observed for 12-24hours for possible neurologic deterioration secondary to intracranial hematoma.

Diagnosis:plain film of skull(axial or tangent)

2.Depressed skull fractures-These usually occur as a result of low-velocity injuries such as blows by small objects.The inner table of the skull invariably suffers greater damage than the outer table.These injuries may result in dual or brain lacteration,and if the depression is greater than the thickness of the skull or if it involves the posterior wall of the frontal sinus,surgical elevation may required.

3.Compound fractures-These are fractures in which the overlying scalp has been lacerated.Proper treatment is essentially the same as with simple fractures and includes adequate wound debridement and closure of the laceration.

4.Basal skull fractures-These exceedingly common fractures are diagnosed largely on clinical grounds.As with liner fractures involving the vault of the skull,basal fractures are important as markers of the severity of injury.In addition,they may cause cerebrospinal fluid leakage,with the attendant risk of meningitis or brain abscess formation.

Cerebrospinal fluid leaks usually result from fractures into the paranasal sinuses or mastoid air cells with laceration of the overlying dura and loss of cerebrospinal fluid into the nose or ears.Basilar skull fractures also may injure cranial nerves that course through the skull base.

Treatment ❧(1) Using antibiotics. ❧(2) Avoiding cough, constipation. ❧(3) If the CSF leakage can not be stopped in four weeks, the operation should be done.

Ping Pong Skull Fracture This is a green stick fracture of the skull , it occurs in the first few months of life when the skull bones are still soft. It is caused after falls when the skull hit the edge of a blunt structure as the edge of a table .It shows as a deformity of the skull , it looks as a shallow trench on the surface of the skull. If large and showing as a significant deformity it can be easily treated by elevating the depressed bone fragment.

Injury to the brain is either localized or diffuse. Localized injury is the result of deformation of the brain at the point of impact, by a small object as a hammer, or a rock or a golf ball. The result is injury to the scalp, skull fracture and this could be associated with dural laceration and underlying brain contusion or laceration. Usually there is a localized surrounding edema around the site of the impact.

Localized injury

DIFFUSE BRAIN INJURY This carries a greater risk of damage to the brain and the mechanisms involved in this injury are acceleration/deceleration injury. injury

In acceleration injury the head is put into motion from a stand still position, as a result of which the different layers of the brain travels at different velocities with shearing effects and rotation of the brain within the skull. The shearing stresses between different layers of the brain result in petechial haemorrhages as well as diffuse axonal injury involving the white matter and brain stem. This is seen in motor vehicles accidents where the car is hit from the back.

Acceleration injury

In deceleration injury the head is brought to a stand still from a moving position as in falls. The same mechanism applies.

Deceleration injury

COMPRESSION INJURY The head is compressed between two solid objects as in motor vehicle accidents. The result is multiple linear fractures particularly in the weak areas of the skull base resulting in multiple cranial nerve injuries.

COMPRESSION INJURY

The extent of the diffuse injury and the axonal damage determines the outcome. The more severe the injury is, more brain damage occurs with more axonal injury . This would be associated with higher morbidity and mortality.

The brain may be injuried directly under the site of impact(coup injuries) or in some instances,diagonally opposite to the point of impact(contrecoup injuries).Because of the rough surface of the floor of the frontal and temporal fossae,the anterior and inferior portions of the frontal and temporal lobes are in particular jeopardy.Abrupt movement of the brain within the skull causes contusion of these areas.

TBI: A biological event within the brain ❧Tissue damage ❧Bleeding ❧Swelling

Mechanisms of Injury ❧Focal ❧Polar ❧Diffuse axonal ❧Secondary insults

Focal

Polar

Diffuse axonal

Secondary

Injury to the brain is caused by rapid deceleration,acceleration,rotation or a combination of these associated with a blow to the head.The initial impact can produce neuronal and axonal disruption,which constitutes the primary jnjury.Any subsequent jnjury complication such as an intracranial hematoma,cerebral edema,hypoxia,hypotension,hydrocephalus or endocrine disturbance characterizes secondary injury,which compounds the initial injury insult.