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Ppt. Patho Head Injury

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Head trauma refers to injury to the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in the medical literature.

The incidence (number of new cases) of head injury is 300 per 100,000 per year (0.3% of the population), with a mortality of 25 per 100,000 in North America and 9 per 100,000 in Britain. Head trauma is a common cause of childhood hospitalization

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Common causes of head injury are : traffic accidents, home and occupational accidents, falls assaults.

-Bicycle accidents are also a common cause of head injury-related death and disability, especially among children.

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► A closed (non-missile) head injury is one in which the skull is not broken.

► 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.

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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).

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Isolated scalp trauma is generally classified as a minor injury. Because its many blood vessels constrict poorly, the blood bleeds porfusely when injured.

Trauma may result in abrasion (brush wound), contusion, lacerartion, or hematoma beneath the layers of the tissue of the scalp( sublageal hematoma).

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A large avulsion ( tearing away) of the scalp may be potentially life-threatening and is a true emergency

Diagnosis of a scalp injury is based on physical examination, inspection, and palpation.

Scalp wounds are potential portals of entry of organisms that cause intracranial infections

Therefore, the area is irrigated before the laceration is sutured, to remove foreign material and to reduce the risk of infection.

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A skull fracture is a break in one or more of the bones in the skull caused by a head injury. It may occur with or without damage of the brain.

Skull Fractures are classified as: Simple Comminuted Depressed Basilar

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A simple ( linear) fracture is a break in the continuity of the bone. It is the most common type of skull fracture, occur

in 69% of patients with severe head injury. Growing fracture a linear fracture can develop

and lengthen as the brain swells. This can cause growth of cysts in the meninges

Diastatic fractures are linear fractures that cause the bones of the skull to separate at the skull sutures in young children whose skull bones have not yet fused

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The bottom row are images from the previous slide, showing the comminuted but undisplaced and undepressed left squamous temporal fracture.

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Comminuted skull fractures, refers to a splintered or multiple fracture line.

Depressed skull fractures, when bone fragments is embeded into brain tissue

- Depressed skull fractures carries a high risk of increasing pressure on the brain, crushing the delicate tissue.

- Depressed skull fractures may require surgery to lift the bones off the brain if they are causing pressure on it.

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Basilar skull fractures, breaks in bones at the base of the skull, require more force to cause than cranial vault fractures.

Basilar fractures have characteristic signs: blood in the sinuses; a clear fluid called cerebrospinal fluid (CSF) leaking from the nose or ears; raccoon eyes (bruising of the orbits of the eyes that result from blood collecting there as it leaks from the fracture site); and Battle's sign (caused when blood collects behind the ears and causes bruising).

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Radiologic Examination Physical Examination and Evaluation of

Neurologic Status CT scan MRI ( Magnetic Resonance Imaging) Cerebral Angiography

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Depends on the severity and distribution of the underlying brain injury

Localized pain ( usually suggests that a fracture is present)

Swelling in the region of the fracture

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Nondepressed skull fractures generally do not require surgical treatment; however, close observation of the patient is essential.

Depressed skull fractures usually requires surgery, particularly if contaminated or deformed fractures are present.

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Concussion Cerebral Contusion Epidural hematoma Subdural hematoma Diffuse axonal injury

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Concussion, from the Latin concutera ("to shake violently") or the Latin concussus ("action of striking together"), is the most common type of traumatic brain injury (TBI). It is a temporary loss of neurologic function with no apparent structural damage to the brain.

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A concussion may temporarily or permanently damage nerve tissue, producing amnesia, irritability, and fatigue; memory is often impaired. Recovery from a concussion is generally complete and prompt after less severe injuries.

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Acceleration (g-forces) can exert rotational forces in the brain, especially the midbrain and diencephalon.

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A concussion generally involves a period of unconsciousness lasting from a few seconds to a few minutes. The jarring of the brain may be so light as to cause only dizziness and spots before the eyes ( “seeing the stars”), or it may be severe enough to cause complete loss of consciousness for a time. Sometimes, post traumatic amnesia may occur lasting up to 24 hours.

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Increased pressure on the brain stem probably accounts for the slowing or temporary suspension of respiration and the reduced pulse rate that accompany a concussion; additional symptoms include pallor, sweating, and a drop in blood pressure. Dizziness, nausea, and a dull, restless feeling often follow a return to consciousness. Aftereffects such as headaches, dizziness, and nervousness may continue for several days, weeks, or even years after the initial injury.

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Common causes include: sports injuries, bicycle accidents, car accidents, and falls; the latter two are the most

frequent causes among adults.

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Concussion may be caused by a blow to the head, or by acceleration forces without a direct impact. The forces involved disrupt cellular processes in the brain for days or weeks. On the battlefield, MTBI is a potential consequence of nearby explosions.

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The patient may be hospitalized overnight for rest and observation or discharged from the hospital in a relatively short time after a concussion.

Treatment involves observing the patient for headache, irritability, and anxiety.

( the occurrence of these symptoms after injury is referred to a post concussion syndrome)

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Cerebral contusion, Latin contusio cerebri, a form of traumatic brain injury, is a bruise of the brain tissue. Like bruises in other tissues, cerebral contusion can be associated with multiple microhemorrhages, small blood vessel leaks into brain tissue. Contusion occurs in 20–30% of severe head injuries.

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Contusion can present with weakness, lack of motor coordination, numbness, aphasia, and memory and cognitive problems. Signs depend on the contusion's location in the brain.

Contusions typically form in a wedge-shape with the widest part in the outermost part of the brain.

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Often caused by a blow to the head, contusions commonly occur in coup or

contre-coup injuries. In coup injuries, the brain is injured

directly under the area of impact, while in contrecoup injuries it is injured on the side opposite the impact.

Contusions occur primarily in the cortical tissue, especially under the site of impact or in areas of the brain located near sharp ridges on the inside of the skull.

Multiple petechial hemorrhages has sharp ridges by which a moving brain can be injured.

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Numerous small contusions from broken capillaries that occur in grey matter under the cortex.

Caused by shearing injuries at the time of impact, these contusions occur especially at the junction between grey and white matter and in the upper brain stem, basal ganglia, thalamus and areas near the third ventricle.

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The hemorrhages can occur as the result of brain herniation, which can cause arteries to tear and bleed. A type of diffuse brain injury, multiple petechial hemorrhages are not always visible using current imaging techniques like CT and MRI scans.

MRI showing damage due to herniation in a patient who had had contusions in the frontal lobes.

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Since cerebral swelling presents a danger to the patient, treatment of cerebral contusion aims to prevent swelling. Measures to avoid swelling include prevention of:

hypotension (low blood pressure), hyponatremia (insufficient sodium), hypercapnia (excess carbon dioxide in the blood). Due to the danger of increased intracranial

pressure, surgery may be necessary to reduce it. People with cerebral contusion may require intensive care and close monitoring

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Epidural or extradural hematoma (haematoma) is a type of traumatic brain injury (TBI) in which a buildup of blood occurs between the dura mater (the tough outer membrane of the central nervous system) and the skull. The dura mater also covers the spine, so epidural bleeds may also occur in the spinal column.

Nontraumatic epidural hematoma in a young woman. The grey area in the top left is organizing hem-atoma, causing midline shift and compression of the ventricle.

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Often due to trauma, the condition is potentially deadly because the buildup of blood may increase pressure in the intracranial space and compress delicate brain tissue. The condition is present in one to three percent of head injuries. Between 15 and 20% of patients with epidural hematomas die of the injury.

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Acute Extradural Haematoma:Intracranial haematoma - non-evacuated

This scan shows another intracranial haematoma, namely an extradural. You will note that this haematoma has a concave shape, a bit like the human lens and this is because it is occurring between the bone and the dura and is not actually lying on the surface of the brain itself. The points of attachment of the dura limit the extension of this haematoma anteriorly and posteriorly. You can see that there is shift of the midline. Look at the frontal horns in their relation to the falx cerebri (falx cerebri is outlined on the normal scan). This scan would be classified "Intracranial haematoma - non evacuated."

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Symptoms are caused by the expanding hematoma. Usually a momentary loss of consciousness occurs at the time of injury, followed by an interval of apparent recovery ( lucid interval)

Epidural bleeds, like subdural and subarachnoid hemorrhages, are extra-axial bleeds, occurring outside of the brain tissue, while intra-axial hemorrhages, including intraparenchymal and intraventricular hemorrhages, occur within it.

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Epidural bleeding is rapid because it is usually from arteries, which are high pressure. Epidural bleeds from arteries can grow until they reach their peak size at six to eight hours post injury, spilling from 25 to 75 cubic centimeters of blood into the intracranial space. As the hematoma expands, it strips the dura from the inside of the skull, causing an intense headache.

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Epidural bleeds can become large and raise intracranial pressure, causing the brain to shift, lose blood supply, or be crushed against the skull. Larger hematomas cause more damage. Epidural bleeds can quickly expand and compress the brain stem, causing unconsciousness, abnormal posturing, and abnormal pupil responses to light.

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The main cause of epidural hematoma is usually traumatic, although spontaneous hemorrhage is known to occur.

Hemorrhages commonly result from acceleration-deceleration trauma and transverse forces. 10% of epidural bleeds may be venous.

The interior of the skull has sharp ridges by which a moving brain can be injured.

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Epidural hematoma commonly results from a blow to the side of the head. The brain may be injured by prominences on the inside of the skull as it scrapes past them.

Epidural hematoma is usually found on the same side of the brain that was impacted by the blow, but on very rare occasions it can be due to a contrecoup injury.

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As with other types of intracranial hematomas, the blood may be aspirated surgically to remove the mass and reduce the pressure it puts on the brain.

The hematoma is neurosurgically evacuated through a burr hole or craniotomy.

The diagnosis of epidural hematoma requires a patient to be cared for in a facility with a neurosurgeon on call to decompress the hematoma if necessary and stop the bleed by ligating the injured vessel branches.

As with other types of intracranial hematomas, the blood may be aspirated surgically to remove the mass and reduce the pressure it puts on the brain.

The hematoma is neurosurgically evacuated through a burr hole or craniotomy.

The diagnosis of epidural hematoma requires a patient to be cared for in a facility with a neurosurgeon on call to decompress the hematoma if necessary and stop the bleed by ligating the injured vessel branches.

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If they can receive surgery quickly. In TBI patients with epidural hematomas, prognosis is better if there was a lucid interval (a period of consciousness before coma returns) than if the patient was comatose from the time of injury. Unlike most forms of TBI, people with epidural hematoma and a Glasgow Coma Score of 3 (the lowest score) are expected to make a worst outcome.

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A subdural hematoma or subdural haematoma (British English) also known as a subdural hemorrhage (SDH) is a type of hematoma, a form of traumatic brain injury in which blood gathers within the inner meningeal layer of the dura mater (the outer protective covering of the brain).

Epidural hematomas are usually caused by tears in arteries, resulting in a buildup of blood between the dura and the skull.

Another subdural hematoma.

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Acute Subdural Haematoma Demonstrating Midline Shift:Midline shift >5mm

Intracranial haematoma - non evacuated Cortical contusion >1cm in diameter

Obliteration of 3rd Ventricle (not seen - refer to normal CT scan)This CT scan shows a right sided acute haematoma, as well as an associated cerebral contusion (bruising). The true midline has been outlined by yellow dots and you can see that the frontal horns of the lateral ventricles have been pushed over to the left. In addition, the third ventricle is now not visible and it is also extremely difficult to make out the basal cisterns. This scan demonstrates four of the features which are included on the Early Outcome Form, namely midline shift greater than 5mm, intracranial haematoma - non evacuated, cortical contusion greater than 1cm in diameter and obliteration of the third ventricle. This haematoma requires surgical evacuation, otherwise deterioration of the patient's condition is inevitable.

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Acute Subdural HaematomaIntracranial haematoma - non-evacuated

This scan demonstrates a left sided acute subdural haematoma. The scan is taken through a slightly higher part of the brain and shows the bodies of the lateral ventricles. The left lateral ventricle has been compressed and the midline is deviating to the right. The right lateral ventricle is actually slightly larger than normal and this is because the increased pressure is preventing escape of the cerebrospinal fluid from that ventricle. Dilatation of the contralateral ventricle like this indicates that there is very significant pressure on the brain. This scan would be classified as "Intracranial haematoma - non evacuated" on the Early Outcome Form.

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Symptoms of subdural hemorrhage have a slower onset than those of epidural hemorrhages because the lower pressure veins bleed more slowly than arteries. Thus, signs and symptoms may show up within 24 hours but can be delayed as much as 2 weeks. If the bleeds are large enough to put pressure on the brain, signs of increased ICP or damage to part of the brain will be present.

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A history of recent head injury

Loss of consciousness or fluctuating levels of consciousness

Irritability Seizures Pain Numbness Headache (either

constant or fluctuating) Dizziness Disorientation Amnesia

Weakness or lethargy Nausea or vomiting Loss of appetite Personality changes Inability to speak or

slurred speech Ataxia, or difficulty

walking Altered breathing

patterns Blurred Vision Deviated gaze, or

abnormal movement of the eyes.

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Subdural hematomas are most often caused by head injury, when fast changing velocities within the skull may stretch and tear small bridging veins.

Subdural hematomas due to head injury are described as traumatic. Much more common than epidural hemorrhages, subdural hemorrhages generally result from shearing injuries due to various rotational or linear forces.

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Subdural hemorrhage is a classic finding in shaken baby syndrome, in which similar shearing forces classically cause intra- and pre-retinal hemorrhages.

Subdural hematoma is also commonly seen in the elderly and in alcoholics, who have evidence of cerebral atrophy. Cerebral atrophy increases the length the bridging veins have to traverse between the two meningeal layers, hence increasing the likelihood of shearing forces causing a tear.

It is also more common in patients on anticoagulants, especially aspirin and warfarin. Patients on these medications can have a subdural hematoma with a minor injury.

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Diffuse axonal injury involves widespread damage to axons in the cerebral hemispheres, corpus callosum, and brain stem.

It can be seen with mild, moderate, or severe head trauma.

The patient experiences no lucid intervals, immediate coma, decorticate and decerebrate posturing and global cerebral edema.

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Diffuse Axonal Injury:One or more petechial haemorrhages within the brain

The presence of petechial haemorrhages is usually an indication of a very severe primary brain injury. Petechial haemorrhages tend to occur at the interface of grey and white matter. It can also occur in the dorsolateral quadrant of the midbrain at the middle orange arrow, as well as elsewhere within the brain substance. Note on this scan, that the lateral ventricles and the third ventricle are visible and there is no midline shift. It is often a characteristic of diffuse axonal injury, in which there are numerous petechial haemorrhages that there is no evidence of brain swelling, or midline shift. This scan would be classified as showing one, or more, petechial haemorrhages within the brain.

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DAI is classified into grades based on severity of the injury:

Grade I, widespread axonal damage is present but no focal abnormalities are seen.

Grade II, damage found in Grade I is present in addition to focal abnormalities, especially in the corpus callosum.

Grade III damage encompasses both Grades I and II plus rostral brain stem injury and often tears in the tissue.

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DAI is the result of traumatic shearing forces that occur when the head is rapidly accelerated or decelerated, as may occur in auto accidents, falls, and assaults. It usually results from rotational forces or severe deceleration.

Vehicle accidents are the most frequent cause of DAI; it can also occur as the result of child abuse such as in shaken baby syndrome

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The major cause of damage in DAI is the disruption of axons, the neural processes that allow one neuron to communicate with another.

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Diagnosis is made by clinical signs in conjunction with a CT or MRI scan.

DAI is difficult to detect because it does not show up well on CT scans or with other macroscopic imaging techniques, though it shows up microscopically.