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Understanding Brain Anatomy and Head Injuries

Gain knowledge of the brain's anatomy, head injuries, & neurological assessment. Learn about skull fractures, brain lobes, ventricles, CSF, and intra-cranial pressure.

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Understanding Brain Anatomy and Head Injuries

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  1. Aims Of The Session • To gain knowledge and understanding of the anatomy of the brain • To gain knowledge and understanding about head injuries • To gain knowledge and understanding of neurological assessment and the skills involved in assessing patients

  2. Introduction • Each year 1.4 million people in the UK suffer head injury, 150,000 will be admitted to hospital with most being discharged within 48 hours.

  3. Indications For Admission • Patients who are unwell or who have a risk of later deterioration from an intracranial haematoma • Patients who have lost consciousness or who have suffered amnesia of more than 5 min • Presence of abnormal neurological findings • Skull fractures

  4. Indications For Surgery • Elevation of depressed skull fracture • Evacuation of a haematoma • Arrest of a cerebral bleed

  5. Anatomy - Bones Of The Skull • Support and protect the brain • Frontal • Temporal • Parietal • Occipital

  6. The Coverings of the Brain • Meninges: three connective tissue membranes that cover the brain and spinal cord • Dura mater - white fibrous tissue: outer layer • Arachnoid - delicate membranes: middle layer contains cerebrospinal fluid • Pia mater - inner layer contains blood vessels

  7. Major Parts Of The Brain • Cerebrum • Largest area of the brain • Divided into left and right hemispheres • Right cerebral hemisphere controls the left side of the body • Left cerebral hemisphere controls the right side of the body • Each hemisphere is divided into four lobes – frontal, parietal, temporal, occipital

  8. Lobes Of The Brain • Frontal Lobe • associated with reasoning, planning, parts of speech, movement, emotions, and problem solving • Parietal Lobe • associated with movement, orientation, recognition, perception of stimuli • Occipital Lobe • associated with visual processing • Temporal Lobe • associated with perception and recognition of auditory stimuli, memory, and speech

  9. Major Parts Of The Brain • Cerebellum • Second largest part of the brain • It is connected to the brain stem • Helps provide smooth coordinated body movement

  10. Major Parts Of The Brain • Brain Stem • is responsible for basic vital life functions such as breathing, heartbeat, and blood pressure. • Midbrain • Pons • Medulla oblongata

  11. Ventricles

  12. CSF And Ventricles • Cerebrospinal fluid • Clear watery substance made in the ventricles by the choroid plexus • Cushions the brain and spinal cord • It circulates through the ventricles and sub-arachnoid space

  13. Intra-cranial Pressure • When intra-cranial pressure begins to rise, the body’s own compensatory mechanisms include decreasing the production of CSF and restricting the blood flow to the brain (by vasoconstriction). • Once the capacity of these compensatory mechanisms is exceeded, the intra-cranial pressure can continue to rise. • In addition, as intra-cranial pressure rises, the cerebral blood vessels are constricted, reducing blood flow further.

  14. Intra-cranial Pressure • Normal intracranial pressure (ICP), usually measured as a mean pressure, is often cited as 0-10mmHg • Sustained high pressures can cause 'coning' (tentorial herniation), when brainstem tissue is forced through the foramen magnum into the spinal cord.

  15. Cushing’s Response • The following three symptoms are known collectively as Cushing's response triad • Hypertension. • Bradycardia. • Abnormal respiratory pattern. • They indicate brainstem dysfunction and exhaustion of compliance (Hickey 1997a); without urgent intervention, patients are likely to die.

  16. Causes Of Raised Intra-Cranial Pressure • Anything that increases the volume of brain tissue, blood or CSF within the skull will raise intra-cranial pressure: • volume of brain (cerebral oedema): - injury • infection • hypoxia • CSF (eg due to obstruction to drainage) • haemorrhage (eg subarachnoid) • tumour • haematoma

  17. Head Injuries • Head injury is most likely to happen to young men, with an average age of 30 who are involved in road traffic accidents • Other causes of adult injuries include contact sports, such as rugby and boxing • Children often suffer head injury from bicycle accidents or pedestrian-vehicle collisions and very young children and old adults can suffer injury from falls

  18. Head Injuries • The head is vulnerable to injury • Analogy for a head injury • Blancmange (brain) • Wrapped in cling film (arachnoid mater) • In a paper bag (dura mater) • Inside a cardboard box (skull) • Wrapped in brown paper (skin) • Any layer may be damaged by • Direct impact on the box (blow) • Dropping the box (fall) • Shaking the box (acceleration/deceleration)

  19. Head Injuries • Skull fracture • Simple: • Linear or hairline • Depressed fracture – fragments are driven inwards

  20. Head Injuries • Intracranial haemorrhage • The dura and arachnoid membranes and their associated blood vessels are readily torn by impact or fractured bone fragments • There are four types of intracranial haemorrhages • Extradural • Subdural • Subarachnoid • Intracerebral

  21. Head Injuries • Extradural haemorrhage • Results from rupture of one of the meningeal arteries that run between the dura and the skull. • The middle meningeal artery is most commonly affected. • Usual cause is a skull fracture

  22. Head Injuries • Subdural haemorrhage • More common than extradural haemorrage • Associated with sudden jarring or rotation of the head • Shears and tears the small veins which bridge the gap between the dura and cortical surface of the brain

  23. Head Injuries • Intracerebral haemorrhage: • May benatural, due to spontaneous rupture of a small blood vessel which has been weakened by the effects long-standing high blood pressure. • Traumatic due to extension of haemorrhage from surface contusions deep into the substance of the brain.

  24. Assessment Of Head Injuries • Glasgow Coma Scale (GCS) • Scoring system originally described for patients with head injury; now applied to other causes of coma • The Glasgow coma scale (GCS) is a reliable and universally comparable way of recording the conscious state of a person.

  25. Assessment Of Head Injuries • Three types of response are measured, and added together to give an overall score. • The lower the score the lower the patient's conscious state. • GCS 13-15 (Mild) • GCS 9-12 (Moderate) • GCS 3-8 (Severe)

  26. E + M + V = 3 to 15 • 8 is the critical score • Less than or equal to 8 at 6 hours - 50% die • 9-11 = moderate severity • Greater than or equal to 12 = minor injury • Coma is defined as: • (1) not opening eyes, • (2) not obeying commands • (3) not uttering understandable words.

  27. DECORTICATE Decorticate posturing is also called decorticate response, decorticate rigidity, flexor posturing

  28. DECEREBRATE Decerebrate posturing :typically the head is arched back, the arms are extended by the sides, and the legs are extended

  29. Neurological Observations • Assess conscious level • Speech • Mental state • Eyes • Can the patient see • Is there an eye injury – eye maybe closed • Can the patient focus

  30. Neurological Assessment • It is important to assess a patient’s neurological state if a patient has a head injury, in a coma or have had neuro surgery performed • This assessment can indicate quite quickly a need for intervention • Neurological assessment may be carried out every fifteen minutes or half hourly depending on the condition of the patient • The most serious situation is the deterioration of conscious level due to raised intracranial pressure

  31. Patient A 21 yr Male Bicycle Trauma (no PMH) Can’t open eyes Can’t answer questions Doesn’t respond to stimuli What is the GCS ?

  32. Patient B 52 Female (2 week history of headache) Responds to verbal commands Responds to questions is coherent but confused Localises to pain (moves hand away from site) What is the GCS ?

  33. Neurological Observations • Pupillary observations • What is their size – normal, moderately dilated or fully dilated • What is the pupil reaction to light – brisk, sluggish or fixed

  34. Neurological Observations • Limb movement & tone • Can the patient move their limbs on command • Movement is it normal, weak, severely weak or absent • If absent does the patient respond to painful stimuli • Is there any abnormal involuntary movement

  35. Neurological Observations • Blood pressure • Pulse • Respiration • Temperature

  36. Headache Vomiting Increasing drowsiness Deterioration in mental and verbal response Inequality of the pupils with sluggish reaction to light Development of hemiparesis Incontinence Pulse rate becomes slower Blood pressure rises Respiration – depth, rate and rhythm change when patient loses consciousness Signs Of Raised ICP

  37. Any Questions?

  38. Bibliography • Verran B, Aisbett P.(1988) Neurological and Neurosurgical Nursing. London Edward Arnold Publishing

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