Transcript mechanical

Mechanical Injuries
Of
Brain and Meniges
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1 Traumatic
Lesions
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2 Alterations
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1
Traumatic Lesions
Extracerebral lesions
Intracerebral lesions
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Traumatic Lesions
Close injury
Open injury
Extracerebral Lesions
Epidural bleeding
Subdural bleeding
Subaracnoid bleeding
Intraventricular bleeding
Intracerebral Lesions
Contusions
Lacerations (or Wounds)
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2
Alterations
Circulatory disorder
Necroses and hemorrhages
Post-traumatic hydrocephalus
Secondary infections
Fat and air embolism
Epidural
Bleeding
Epidural Bleeding
Epidural / Extradural
Hemorrhage / Hematoma
Causes
Skull fracture
Separation of dura and skull bone
Tear of a dural artery ,its branches
and/or occasionally of a vein
Most common site: lateral convexity
of a cerebral hemisphere
Location: it almost always at the site
of a skull fracture
Uncommon occur in the elderly
Children: skull deformation with
separation of the dura from the bone
without skull fracture
Acute hematoma: artery bleeding
Delayed hematoma: venous bleeding,
transient arterial spasm
Progression of the bleeding
Space occupying hematoma
Increase intracranial pressure
Confusion
Alteration of consciousness
Pupillary dilatation: on the hematoma side
Central respiratory failure
If venous bleeding ,or transient
arterial spasm: Lucid interval
Consciousness (may be) ,no signs of
confusion: occipital poles and/or
cerebellum
Chronic Epidural Hematoma
The hematoma spontaneously shrinks and
becomes encapsulated by fibrous
connective tissue.
Subdural
Bleeding
Subdural bleeding
Trauma
Rupture of aneurysm
Arteriovenous malformation
Vein:
- Tearing of one
or
- Several bridging vein
- Insignificant trauma (sometime):
abnormally located blood vessels
Artery:
- particularly in branches of the middle
cerebral artery
- severe cortical contusions and bleeding
into subarachnoid space:
(usually) tears of arachnoid membrane
Artery:
- More frequently on the side opposite
the impact
- (May) without brain contusions
or significant subarachnoid hemorrhage
Time of onset
Acute: within 12 to 24 hr.
Subacute: from 24 hr. to 7 d.
Chronic: more than 7 d.
Most Location: over the convexities and
the lateral aspects of the cerebral
hemisphere
Often: extend over the base of frontal and
temporal lobes
Occasionally: between the hemisphere
In skull intact: occur as often as with skull
fracture
Rare in the posterior cranial fossa , around
the brain stem and cerebellum
Chronic Subdural Hematoma
Enlargement if untreat
Isotonicity
Local presence of fibrinolytic enzymes:
bleeding tendency
Subaracnoid
Bleeding
Subaracnoid bleeding
Trauma / Nontrauma
Extension of intraventricular hemorrhage
Moderately severe blow to the face or
forehead
Sudden ,usually severe hyperextension of
the head , as from a fall onto the forehead
Subarachnoid over the brain stem and
basal cisterns = hydrocephalus
Forgetfulness , confusion , psychotic state
Spasticity of the lower extremities
Intraventricular
bleeding
Intraventricular bleeding
Most often arterial in origin
Trauma
Non-trauma: such as rupture AVM or
Aneurysms
Intracerebral
Lesions
Contusions
Lacerations (Wounds)
Contusions
Contusion hemorrhage
Contusion necrosis
Contusion tear
Intracerebral Hematoma
In the deeper portions of contusions
More frequent in the frontal and /or
temporal lobes
Location: white matter > grey matter
Intracerebral Hematoma
Secondary rupture into the ventricular
system and/or the subarachnoid space
usually does not occur.
Lacerations
Stab wounds
Gunshot wounds
Gunshot wounds
Shearing forces within brain tissue
Expansile cavitation
Distant contusions (hemorrhages)
Classification of
Contusions
According to causative mechanism
Depending on site and direction of impact
: Coup , Intermediary coup , Contrecoup
Independent of site and direction of impact
: Fracture contusion , Gliding contusion ,
Herniation contusion
Axonal injury
Shearing forces due to blunt head injuries
Focal , diffuse
Early ,the areas: little or no change on
gross examination of the white matter
Older lesions: slightly gray pallor
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Alterations
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Alterations
Circulatory disorder
Necroses and hemorrhages
Post-traumatic hydrocephalus
Secondary infections
Fat and air embolism
Circulatory disorder
Swelling of the brain: edema and cell
necrosis
Usually reversible
Perifocal: surrounding a 1๐ brain lesion
Generalize: a primary lesion , shock
Other rare causes
Obstruction of the superior sagittal sinus
Traumatic thrombus or obstruction in
internal carotid artery
Necroses/Hemorrhages
Vascular compression
Shearing lesions
Necroses/Hemorrhages
Many lesion are large: such as midbrain
and pons
If rapidly progressing space occupying
lesion: secondary lesion may appear
within 30 mins. After injury
Hemorrhage : sometimes small or absent
Hydrocephalus
Traumatic or Non-traumatic cause
White matter loss following a shearing
lesion and degeneration of myelinated
axons
Distension of ventricles by elevated
pressure of the CSF
Secondary infections
Meningitis
Intracerebral abscesses
Meningitis
An infected open injury caused by a
foreign body
A fracture in the wall of one of the cranial
sinuses associated with a tear in the dura
and arachnoid
Intracerebral abscesses
In the vicinity of the primary lesion
Complication: rupture into the underlying
ventricle (Pyocephalus)
Fat and air embolism
Primary or Secondary lesions
Fat embolism: fractures , stab wound at
neck
Air embolism: stab wound at neck , a skull
fracture lacerating a paranasal dural sinus