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Scalp protects skull but infection can enter through veins draining the face or through the loose connective tissue layer Trauma to skull can produce hematomas.

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Presentation on theme: "Scalp protects skull but infection can enter through veins draining the face or through the loose connective tissue layer Trauma to skull can produce hematomas."— Presentation transcript:

1 Scalp protects skull but infection can enter through veins draining the face or through the loose connective tissue layer Trauma to skull can produce hematomas or fractures that can let infection enter Cerebrospinal fluid protects the brain, but can carry infection Meningeal layers can have hemorrhages & hematomas

2 Vertebral column can dislocate, fracture, or disks can protrude, which can affect neural function Lordosis – exaggerated lumbar curvature Kyphosis – exaggerated thoracic curvature Scoliosis – lateral displacement Discs decrease in size & flexibility with age and can herniate

3 Autoregulation of blood flow guarantees adequate blood supply to the brain Infarcts occur at margins of adjacent vascular fields that supply the cortex – watershed zones, after impaired perfusion (fibrillation) or oxygenation (CO poisoning, drowning) Areas of infarct undergo liquefaction nerosis, leaving a cyst – lacunae Vasogenic edema – with inflammation Brain tissue swells if capillaries get permeable & allow accumulation of fluid Cytotoxic edema – results from hypoxia – intracellular swelling

4 Expansion of brain, CSF, blood in the skull can increase intracranial pressure, impair perfusion, compress, shift or tear tissue, herniation can occur Compensations include decreased CSF & blood volume, with eventual hypoxia that increase blood pressure, eventually coma & death Oversecretion, impaired absorption, blocked circulation of CSF expands the ventricles – hydrocephalus – alleviated by shunting

5 Consciousness levels can be measured to assess neural function Causes of coma include alcohol or barbiturate overdose, trauma, stroke, epilepsy, meningitis, diabetes, kidney failure, heart disease Reflexes & automatic functions aid in localization of CNS lesions

6 Neural tube defects can lead to defects in the bone or meninges, abnormal development of tissue - spin bifida in spinal cord, anencephaly in the brain

7 Aneurysms are dilation of an artery at an injury or weak side, usually by the circle of Willis – berry or fusiform, or secondary to hypertension – microaneurysms Hemorrhage causes violent headaches, blood in the CSF Subarachnoid vasospasms happen spontaneously or secondary to subarachnoid hemorrhage Arteriovenous malformation are congenital and can cause ischemia and hemorrhage

8 Infection or inflammation can cause clots in cerebral veins or venous sinuses Usually arise from ear, sinuses, scalp, nasal cavity, or the face

9 Cerebrovascular accidents occur when blood flow is impaired by occlusion or hemorrhage – will affect function controlled by the area More common in people with hypertension, heart disease, hypercholesterolemia, diabetes, atherosclerosis, oral contraceptive use, smokers TIA – brief vasospasm of an artery from a developing plaque but are temporary and reversible Amaurosis fugax with TIA in ophthalmic artery

10 Thrombotic CVA is from a thrombus on a plaque, usually due to atherosclerosis, asymptomatic until major stenosis blocks flow Ischemia is followed by infarct & liquefaction necrosis embolic CVA’s are 2 nd most common, usually from a-fib, but also from fractures or tumors - they occur more rapidly Hemorrhagic CVA can produce a hematoma mass, usually because of hypertension and aneurisms, blood can enter ventricles or subarachnoid space

11 Bacterial infection of subarachnoid space – pyogenic meningitis – causes stiff neck, fever, vomiting, + Brudzinski & Kernig signs Nisseria meningitides, streptococcus pneumoniae, hemophilus influenzae most common causes Other bacteria are syphilis, lyme disease, tuberculosis can affect brain tissue Viral infections can cause viral meningitis & fatal encephalitis

12 Varicella & measles virus remains in nervous tissue Reye’s syndrome is postviral, affects the CNS, seen after aspirin use Brain abscesses are treated with antibiotics CNS tumors vary between children & adults Adult tumors arise in glial cells that still undergo mitosis, secondary metastasis from lung, breast, skin, kidney cancers Stem cell tumors usually arise in children

13 Drugs that affect autonomic function produce broad or focused effects by blocking or stimulating receptors Peripheral nerve injuries can repair, 1.5mm/day; not central lesions because of atrophy and scar tissue Peripheral nerve injuries - decreased muscle tone, weakness or paralysis of voluntary movement, loss of reflexes, muscle atrophy Upper motor neuron – increased muscle tone, weakness or loss of voluntary movement, increased reflexes, abnormal plantar reflex

14 Cerebellar lesions cause tremor, difficulty in performing voluntary movements Basal ganglia lesions cause difficulty initiating movement, tremor or other movements at rest, rigidity

15 Parkinson disease – from a lesion in the substantia nigra – loss of dopamine - muscle rigidity, bradykinesia, tremor, stooped posture, shuffling gait, autonomic dysfunction Huntington disease – dominant inheritance – loss of GABA - motor disorder, cognitive impairment, derangement

16 Cerebral palsy – ante or perinatal lesion to a normal nervous system impairs voluntary control, hyperreflexia, symptoms like either basal ganglia or cerebellar dysfunction

17 Muscle diseases, usually from genetic or autoimmune disorders, cause muscle weakness Myasthenia gravis is a disorder of neuromuscular junction, autoimmune loss of neurotransmitter receptors for acetylcholine Acetylcholinesterase inhibitors allow ACh accumulation to counteract loss of receptors

18 Multiple sclerosis – sensory, motor, psychic abnormalities from an immune- mediated attack on central nervous system myelin that leaves scars called plaques Guillain-Barre syndrome is immune attack of peripheral myelin

19 Agents can cause lesions in peripheral nerves Viatmin B12 deficiency can affect spinal cord function, and alcoholic degeneration Korsakoff’s psychosis Entrapment syndrome cause focal lesions, with weakness & impaired sensations

20 Injury to the spinal cord interrupts sensory, motor pathways, with increased reflex activity below the site of the lesion

21 Amyotrophic lateral sclerosis – loss of corticospinal neurons without any cognitive impairment Autosomal recessive disorders: Wednig-Hoffmann disease – weakness – floppy baby syndrome Wohlfart-Kugelberg- Welander disease - loss of motor supply to proximal muscles Friedrech’s Ataxia – thin spinal cord affecting movements

22 Alzheimer disease – progressive loss of cortical neurons, degenerative dementia that affects all mental function Biopsies show neurofibrillary tangles and neuritic plaques of amyloid

23 Seizure – rapidly evolving disturbance of brain function that can produce impaired consciousness, abnormal sensations or mental functioning, or convulsive movements Nonepileptic seizures are secondary to conditions like alcohol withdrawal, meningitis, liver or kidney failure

24 Epileptic seizures result when a relatively permanent change in the environment, input, or nature of cortical gray matter pyramidal cells allows some of them – the focus – to discharge spontaneously & recruit larger areas Pyramidal cells are predisposed to generating seizures

25 Most seizures begin focally and produce temporary recruitment that presents as an aura – mental, sensory, or motor phenomena at the onset;, localized EEG activity, abnormal movements, sensations, consciousness, or psychic function Prodrome – set of symptoms that warns of an impending seizure

26 Partial seizures begin at a limited focus Simple partial seizure can spread to become a complex or generalized (secondarily generalized tonic-clonic seizure) Complex seizures include an alteration of consciousness, may show automatisms – purposeless behaviors Generalized seizures arise instantly with no evidence of focal origin

27 Absence seizures – minor impairments of neural function & consciousness Tonic-clonic grand mal seizures – begin with prodrome, and have jerks Normal consciousness depends on sensory stimulation & processing and integrated function of the reticular activating system, cortex, hippocampus Consciousness is unimpaired in simple partial seizures, impaired in partial complex & specific generalized seizures

28 Grand mal status epilepticus (tonic-clonic status) is medical emergency Acidosis, increased CO2, hypo- glycemia from muscle contraction, can lead to death

29 Evaluation of tendency to have seizures involves routine EEG, CT, MRI drug therapy with a single anticonvulsant is usual medical management


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