Mechanical Injuries Of Brain and Meniges

1๐ Traumatic Lesions 2๐ Alterations

1๐ Traumatic Lesions Extracerebral lesions Intracerebral lesions

1๐ Traumatic Lesions Close injury Open injury

Extracerebral Lesions Epidural bleeding Subdural bleeding Subaracnoid bleeding Intraventricular bleeding

Intracerebral Lesions Contusions Lacerations (or Wounds)

2๐ 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)

Contusions According to causative mechanism 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

2๐ Alterations

2๐ 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