Nervous system 1 introduction raised intracranial pressure and trauma
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Nervous system 1 Introduction, raised intracranial pressure and trauma. Professor John Simpson. This lecture will cover. NS cell reactions to injury raised intracranial pressure, including herniation of the brain traumatic brain injury.

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Nervous system 1 introduction raised intracranial pressure and trauma l.jpg

Nervous system 1Introduction, raised intracranial pressure and trauma

Professor John Simpson


This lecture will cover l.jpg
This lecture will cover

  • NS cell reactions to injury

  • raised intracranial pressure, including herniation of the brain

  • traumatic brain injury



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Why is the NS different? body systems?

  • brain and cord sit in closed spaces

  • autoregulation of blood flow

  • blood-brain barrier

  • high dependency on O2 and glucose

  • absence of lymphatics

  • limited immune surveillance

  • unique cell population with distinctive responses to injury and healing


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Microscopic structure of the nervous system body systems?

  • neurons (essentially end cells)

    • cell bodies - aggregated in grey matter

      • layers, ganglia, columns, nuclei

      • In specific domains

    • cell processes - include

      • axons in bundles in white matter

  • glial cells (capable of dividing)

    • astrocytes, oligodendrocytes and ependyma – neuroectodermal origin

    • microglia – mesodermal origin


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Glial cell roles body systems?

  • astrocytes

    • neuronal support, blood-brain barrier, healing and repair (by gliosis)

  • oligodendrocytes

    • myelin production (~ = Schwann cells in periphery)

  • ependyma

    • related to choroid plexus/CSF production

  • microglia

    • NS macrophages


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Cellular reaction to injury - neurons body systems?

  • cell death

    • in chronic disease, often seen as reduced cellularity

  • cell “degeneration”

    • variety of changes ~ disease, e.g. accumulations, inclusions

  • axonal reaction

    • regeneration possible if only axon damaged



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Symptoms and signs of NS disease body systems?

  • headache

  • neck stiffness

  • coma/impaired consciousness

  • loss or disturbance of movement

  • abnormal reflexes

  • muscle atrophy

  • sensory impairment/paraesthesia

  • visual disturbances

  • tinnitus/deafness


Intracranial pressure icp l.jpg
Intracranial pressure (ICP) body systems?

  • major components of ICP

    • brain, CSF and blood

  • increased volume of any one will raise ICP, unless compensatory reduction in one/both of other components

  • presence of anything else “extra” inside skull will do the same

  • if ICP continues to increase, compensatory mechanisms will fail


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Common causes of raised ICP body systems?

  • intracranial expanding lesions (“space-occupying lesions”) – e.g. tumour, haematoma, abscess

  • hydrocephalus (excess CSF)

  • cerebral oedema – increase in brain water content, due to blood-brain barrier problem

    • localised (e.g. around tumours)

    • generalised (e.g. following severe head injury or hypoxic brain damage)


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Possible effects of raised ICP body systems?

  • compression of veins and ventricles

  • reduced CSF

  • flattening of gyri and narrowing of sulci

  • papilloedema

  • midline shift

  • herniation of parts of brain

  • eventual compression of vital brain stem centres

  • (before skull sutures fused, enlarged cranium)


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Raised intracranial pressure body systems?

Decompensation

- causes “shifts” and herniation

Cushing reflex

- haemodynamic changes

(raised BP, slowed pulse)


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Focal cerebral oedema in body systems?

frontal lobe



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Sites of brain herniation body systems?

  • subfalcine

  • (trans)tentorial

  • tonsillar

  • (also through skull defect in trauma)



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Subfalcine herniation body systems?

  • (= supracallosal or cingulate hernia)

  • usually due to primary abnormality in one cerebral hemisphere

  • ipsilateral cingulate gyrus herniates under the free edge of falx

  • pericallosal arteries are compressed, so possible cerebral infarction

  • anterior cerebral artery may also be affected, causing larger infarct


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Subfalcine hernia body systems?

due to glioblastoma


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Tentorial herniation body systems?

  • medial aspect of temporal lobe through tentorium

    • affects hippocampus

  • midbrain compressed and distorted

    • compressed aqueduct impairs CSF flow (obstructive hydrocephalus)

    • haemorrhage in pons and midbrain

  • risk to

    • ipsilateral 3rd nerve

    • posterior cerebral artery

    • opposite cerebral peduncle


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Tentorial herniation body systems?


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Large tentorial hernia body systems?

due to cerebral glioblastoma


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Brain herniation body systems?


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Pontine haemorrhages after tentorial herniation body systems?

Figure 28-3 Duret hemorrhage involving the brainstem at the junction of the pons and midbrain.

Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 2 February 2007 01:43 PM)

© 2005 Elsevier



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Tonsillar herniation tentorial herniation

  • (= foramen magnum or foraminal herniation = coning)

  • cerebellar tonsils move down – with medulla form “cone” shape

  • exit from 4th ventricle blocked impairing CSF flow (obstructive hydrocephalus)

  • compression of breathing and cardiac centres in medulla


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Tonsillar herniation tentorial herniation


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Cerebellar tonsillar necrosis tentorial herniation

following tonsillar

herniation


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Lumbar puncture tentorial herniation

Lumbar puncture is dangerous and should be avoided if ICP raised. Why?

Is there any way you might check for raised ICP before doing an LP?


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Traumatic brain injury tentorial herniation

  • missile or non-missile - latter commoner

  • in non-missile, primary or secondary damage

    • primary – focal lesions (contusion/tear) or diffuse axonal injury

    • secondary – e.g. traumatic vascular injury with intracranial haematoma, oedema, herniation, infarction, hydrocephalus, infection

  • clinical effects

    • minor (?) - concussion

    • major – e.g. death, epilepsy, persistent vegetative state (PVS), post traumatic dementia


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Brain – tearing missile injury tentorial herniation


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Cerebral contusions tentorial herniation

  • coup

    • immediately under site of injury

  • contre coup

    • at opposite side of brain



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Temporal lobe contusions tentorial herniation


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Coup and contre coup tentorial herniation


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Diffuse axonal injury tentorial herniation

  • particularly in deep white matter

  • even with very minor trauma

  • axonal swelling and focal haemorrhage

  • contribute to cerebral oedema and raised ICP

  • long term effects variable


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Traumatic vascular injury tentorial herniation

  • extradural

    • especially injury to middle meningeal artery

    • classical clinical presentation

  • subdural

    • dural veins, ? shearing stress

    • acute or chronic (? recurrent bleeding)

    • more common in the elderly and in any bleeding diathesis

    • injury often trivial /missed

  • (subarachnoid and intracerebral

    • usually secondary to contusions)


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Skull fracture tentorial herniation


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Extradural v subdural haematoma tentorial herniation



Extradural haemorrhage l.jpg
Extradural haemorrhage tentorial herniation


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Subdural haematoma tentorial herniation


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Subdural haematoma tentorial herniation


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Spinal cord trauma tentorial herniation

  • most often due to accidents and displacement of vertebral column +/- vascular problem

  • cord/nerve root compression, transection etc

  • effects depend on site and severity

    • paraplegia, quadriplegia, respiratory compromise


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