Nervous System

1. Marilyn Rose RT, RDMS Nervous System

2. outline • Physiology • Infections • Meningitis • Osteomyelitis of the skull • Encephalitis • Brain abscess • Tumors • Glioma • Meningioma • Acoustic neuroma • Pituitary adenoma • Craniopharyngioma • Pineal tumors • Chordoma • Metastatic carcinoma

3. Outline contd • Trauma • Skull fracture • Epidural / subdural hematoma • Cerebral contusion • Intracerebral hematoma • Subarachnoid hemorrhage • Carotid artery injury • Facial fractures • Vascular disease • Stroke/ TIA • Intraparenchymal hemorrhage • Subarachnoid hemorrhage • MS • Epilepsy and convulsive disorders • Degenerative disease • Aging • Alzheimer's • Huntington’s dz • Parkinson’s dz • Cerebellar atrophy • Amyotrophic lateral sclerosis ( Lou Gehrig’s Dz) • Hydrocephalus • Sinusitis

4. physiology • CNS - brain and spinal cord • PNS • 12 pairs of cranial nerves • 31 pairs of spinal nerves • Afferent (sensory) - Efferent (motor) • Somatic- striated skeletal muscles • Autonomic- smooth muscles of heart, glandular • Basic unit= neuron • Axon from the nerve body and one or more dendrites with a fatty covering called myelin sheath - > rate of transmission (deterioration= MS) • Involuntary reactions from CNS= reflex arc • Voluntary actions- reaction to stimulation • Synapse- impulses pass from one neuron to another • Cerebrum- two cerebral hemispheres • Gyri/sulci/ fissures • Cortex-outer (gray)cell body - inner(white)nerve fibers • CSF- formed by filtration of plasma from blood in choroid plexus of lat ventricles • Lateral ventricles- connect to 3rd by foramen of Monro • Fourth lies between the cerebellar hemispheres • 3rd and 4th are connected by aqueduct of Sylvius

5. Physiology contd • Cerebral cortex • Receive sensory information from all parts of the body- govern all motor activity • Visual impulses transmitted - posterior • Olfactory (smell) and auditory impulses - lateral • Higher functions like memory and creative thought • Corpus callosum- mass of white matter -connects two cerebral hemispheres • Between cerebrum/spinal cord= brain stem • Midbrain ( mesencephalon) • Pons • Medulla- vomit, cough, sneeze, hiccup, swallow • 12 cranial nerves • Centers for cardiac, vasomotor, respiratory

6. Physiology contd • Cerebellum- two lateral masses with the central vermis • Coordinates activities of groups of muscles to maintain equilibrium and posture • Diencephalon • Between cerebrum and midbrain • Located around 3rd ventricle • Thalamus- relay and processor of sensory information • Hypothalamus- link between mind and body- pleasure / reward • Release hormones • Regulate normal body temperature • Waking state

7. Physiology contd. • Spinal cord- w/in vertebral column • inner core -gray matter • surrounded by white matter tracts • conduct impulses up the cord • down the cord to spinal nerves • Brain/ spinal cord are protected by two layers: • Outer- cranial bone/ vertebral column • Inner- meninges • Pia mater- innermost layer adhering to outer brain and spinal cord • Dura mater- tough outermost covering- 3 extensions • falx cerebri- in longitudnal fissure- cerebral hemispheres • falx cerebelli – cerebellar hemispheres • tentorium cerebelli- covering over the cerebellum- occipital lobe/ cerebrum • Arachnoid membrane- delicate cobweb

8. infections • Meningitis • Acute inflammation of the pia and arachnoid • Middle ear, up resp tract or frontal sinus or by blood from lungs • Bacterial- (most common) • H influenzae in neonates/ peds • Meningococci/ pneumococci in adolescent/ adult • Viral- mumps, polio, herpes • Radiographic: • vascular congestion, edema • otherwise MRI and CT scans are normal • if infection extends…can cause diffuse brain swelling- • MRI and CT are useful in evaluating the complications..a/v vasculitis/ thrombosis, hydrocephalus or abscess. • A spinal tap is necessary to determine the cause • Osteomyelitis of the skull • Caused by direct extension • From paranasal sinus or scalp • Radiographic changes take 1-2 weeks to show • Radiographic: • Small multiple areas of lucency • Reactive sclerosis as bone tries to heal

9. Infections contd • Encephalitis • Viral inflammation • Mild headache/ fever- seizures and coma • 30% in children • Caused by herpes simplex= fatal • Radiographic: • Poor marginated- patchy temporal area • Mass effect is common- midline shift • Toxo- ring enhancement • Brain abscess • Chronic infection- middle ear, paranasal sinus- or systemic infection- pneumonia, bacterial endocarditis, osteomyelitis • Step most common • AIDS- toxo and cryptococcosis are common causes • Radiographic: • Area of abnormal density- poor defined borders • vascular edema • liquafaction • MRI is the best modality

10. Tumors • Intracranial Neoplasm -Manifest • seizure disorders • neurologic deficits • 50 % primary and 50% are mets • Radiographic: • Depend on location/ Site of mass effect • MRI is most sensitive for suspected tumors • Tumor extent and hydrocephalus • Brain stem and posterior fossa • Gliomas- most common primary malignant brain tumor • glial cells • Peak incidence in midlife- rare <30 yrs • Glioblastomas- mainly cerebral, malignant • Astrocytomas- 70% slow growing, infiltrative- pseudocyst • cerebrum, cerebellum, thalamus, optic chiasm and pons • Ependymomas- wall of 4th ventricle- children, lateral vents in adults • Medulloblastoma- rapid growing- disseminated in spinal fluid- subarachnoid • Oligodendrocytomas- slow growing arise in cerebrum- ca++ • Radiographic: • gliomas appear as masses of high signal intensity • single nonhomogeneous mass • glioblastomas have both increased and decreased density • Irregular ring of contrast enhancement

11. Tumors contd • Meningioma • Benign tumors of arachnoid • Attached to dura • Common sites- calvaria, olfactory groove, tuberculum sellae, spinal canal (25% of spine tumors) • Radiographic • Anatomic distortion • Isointense with brain tissue • Thin rim of low intensity, CSF cleft, vascular rim, ca++ w/in • Contrast enhances • Abut ting the dural surface • Acoustic neuroma • Slow growing benign tumor • Solitary or part of neurofibromatosis • Inner auditory canal- vestibular portion • Radiograph • Focal or generalized enlargement of the 8th cranial nerve • Erosion of the auditory canal • Large tumors can compress the 4th ventricle- hydrocephalus

12. Tumors • Pituitary adenoma • Anterior lobe- 10 % all intracranial tumors • Most nonsecreting chromophobe adenomas • Enlarge- adjoining secreting cells w/in sellaturcica are compressed leading to < secretion and < levels of growth hormone, gonadotropin,thyrotropic and ACTH hormones • Can distort optic chiasm • A hormone secreting pituitary tumor • hyperseceretion of growth hormone • gigantism prior to epeiphyses closure - pediatrics • acromegaly - adults • Excess secretion of adrenocorticotropic= • hypersecretion of steroid= Cushing’s disease • TSH= hyperthyroidism, • prolactin= galactorrhea-amenorrhea syndrome • Radiographic • Homogeneous and hyperdense to surrounding brain • Adjacent bone erosion • Compression of optic nerves, 3rd ventricle • MRI is the best modality

13. Tumors • Craniopharyngioma • Benign cystic and solid lesions • < 20 years of age • Arise anterior to sellaturcica from embryonic remnants • Depresses optic chiasm and extend into 3rd ventricle • Radiographic • Ca++ like eggshell on the periphery of a mixed cystic and solid lesion. • Hydrocephalus is Foramen of Monro is compressed • Pineal tumors • Germinomas and teratomas, rapid growing germ cell • Males < 25 yrs • Associated with precocious puberty • Radiographic • Sagittal MRI are ideal • Compress midbrain- lift up the splenium or the corpus callosum • Teratomas can have a mixed intensity- cystic and fat • Punctate ca++ is seen within the mass

14. Tumors • Chodoma • Arise from remnant of the notochord (embryonic neural tube)- or any part of the vertebral column or base of skull • Clivus and lumbosacral region most common • Locally invasive but not metastatic • Radiographic • Bulky mass- ill defined bone destruction or cortical expansion • Cloudlike (flocculent) ca++ can develop within a soft tissue mass • Metastatic carcinoma • Hematogenous spread • Most common metastasis is from the lung and breast • Melanoma, colon cancer , testicular and kidney tumors also cause brain mets • Radiographic • Singel or multiple masses of high signal intensity • Situated at the junction of gray and white matter

15. Trauma- skull • Skull fx • Linear- sharp lucent line on xray- irregular, jagged • Must distinguish from suture- which are serrated, bilateral and symmetrical • Diastaticfx- intersects a suture and courses along it • If fx involves: • vessel laceration= epidural hematoma • Sinus/ mastoid air cells- air is seen in ventricles • fragment of bone can be depressed into the cranial cavity- stellate or star shaped • Need tangential views to appreciate depth. • Basilar skull fx- air/ fluid level in sphenoid sinus • Complication of basal skull fx- CSF leak, meningitis and damage to facial nerve • PRESENSCE OR ABSENCE OF A SKULL FX DOES NOT CORRELATE WITH INTRACRANICAL ABNORMALITIES

16. Trauma- facial • Nasal bone (most common) • Range from simple-nondisplaced, to comminuted with depression of the septum • Best seen on R/L soft tissue lat projection • Blowout • Blow to the front of the orbit- thin orbital floor fx • Modified Water’s • Zygomatic arch • Blow from side of face- inward displacement of central fragments- outward displacement of zygomatic and temporal ends of arch • Jug handle view- submentovertex projection • Tripod • Fx to zygomatic arch and orbital floor- free floating zygoma • Mandible • Oblique views- angle is most common but bilateral fx are also common • Le Fort • Severe injury with separation and formation of large detached fragment- bilat and horizontal fx of the maxillae- type I,II or III

17. Trauma- epidural vs subdural • Epidural • Acute arterial bleed • Most common over parietotemporal convexity • Laceration • High pressure • Rapid mass effect • Acute neurologic symptoms • Radiographic • Biconvex, peripheral, high density • Midline shift to the opposite side • Subdural • Venous bleeding • Ruptured veins between dura and meninges • Low pressure • Chronic course- headache, agitation, confusion, drowsiness and gradual neurologic deficits • Radiographic • Peripheral zone of increased density follows surface of the brain in crescentic, mass effect with displacement of midline structures • Absence of midline shift can indicate bilateral subdural hematomas

18. Trauma-bleed • Cerebral contusion • Movement of the brain within the calvaria after blunt trauma to the skull • Patient looses consciousness- cannot remember • Radiographic • Low density edema, multiple small areas of hemorrhage • Frontal and anterior temporal regions most common • Post IV contrast will enhance for several weeks • Intracerebralhematoma • Shearing forces to intraparenchymal arteries • @ the junction of gray and white matter • Cause traumatic aneurysms to rupture • Radiographic • Well-circumscribed homogeneous, high density surrounded by low density edema- becomes isodense • Subarachnoid hemorrhage • Injury to surface veins, cerebral parenchyma or cortical arteries • Bleeding into ventricular system • Radiographic • Increased density within the basilar cistern, cerebral fissure and sulci • Identifying the falx on noncon CT is an indication of of subarachnoid blood

19. Trauma- bleed • Carotid artery injury • Extracerebralcarotid • injured from penetrating trauma- gunshot or stab • Trauma to internal carotid associated with 50% of traumatic fistulas • Radiographic • Angiography- demonstrate a laceration • dissection, thrombotic occlusion • Hyperextension- motor vehicle accident • intimal damage to carotid or vertebral- pseudoaneurysm • Traumatic arteriovenous fistulas arise between internal carotid and cavernous sinus Lt carotid dissection Traumatic aneurysm

20. Vascular disease • (1) Stroke • Sudden focal neurological deficit • Range from hemiplegia- coma to a trivial neurologic disorder • Neurologic defect depends on artery involved • Acute brain infarction- internal carotid artery • Symptoms- acute hemiparesis, dysarthria • Radiographic- rule out other causes for the symptoms • Rule out intracranial hemorrhage before using anticoagulants • Radiographic • Non con CT or MRI- best to evaluate for stroke • IV contrast is contraindicated- blood brain barrier - > edema and slower recovery • CT can be normal with a small infarct- large- will show a triangular shape hypodensity • Mass effect is maximal at 7-10 days • As the Infarct ages-brain tissue atrophies and adjacent sulci and ventricles enlarge • MRA is more sensitive to evaluate the edema and evolution

21. Vascular disease • (2) TIA • Manifest as focal neurological - resolve within 24 hours • May result from emboli – plaque • Temporary occlusion of cerebral vessels • Stenosis of an extracerebral artery- reduction in blood perfusion to the brain • 2/3 athrosclerotic strokes are preceded by TIA • Radiographic • Most common location of surgically treatable athroscleroticdz is carotid bifurcation in the neck • Asymptomatic bruit • Carotid duplex ultrasound is the preferred method to begin evaluation of the neck vessels. • Second evaluation is done by a MRA • May still need angiography or can rule it out with the US and MRA • Stenosis >60 % indicated advanced disease and requires surgical intervention • Anticoagulation therapy or endarterectomy

22. Vascular disease • (3) intraparenchymal hemorrhage • Principal cause- hypertensive vascular disease • Less common- rupture of Berry aneurysm or AVM • Significant mass effect • HTN hemorrhage most common in basal ganglia, white matter, thalamus, cerebral hemispheres and pons • Common complication is hemorrhage into ventricular system or subarachnoid space (subarachnoid hemorrhage) • Radiographic • MRI or non CON CT • Fresh hematoma- homogeneous dense round to oval shape • Hematoma- ventricular compression • considerably large- midline shift and brain herniation • Contrast enhancement develops around the periphery after 7-10 days • If pt has an aneurysm- it is important to locate the number of them • < 20 years of age- AVM is most common cause • On MRI a mass of vascular structures or CT an irregular tangle of vessels after contrast Subarachnoid- Berry rupture

23. Multiple Sclerosis (MS) • Most common demyelinating disorder • Recurrent attacks of focal neurologic deficits • Spinal cord, optic nerves ,white matter -brain • Peak incidence- 20-40 years- women • Multiple relapse and remission • Impairment of nerve conduction • degeneration of myelin sheaths- • Symptoms- • double vision, nystagmus(involuntary movement of eyeball in all directions), loss of balance and poor coordination, shaking tremor, muscular weakness, difficulty in speaking clearly and bladder dysfunction • Radiographic • MRI best modality • Scattered plaques of demyelination involve primarily • Periventricular white matter, cerebellum, brainstem and spinal cord • Optic nerve or chiasm- require contrast • CT during an acute episode and distinguish old plaque (non enhancing) from new active foci (enhancing) lesions.

24. Epilepsy/ Convulsive • Condition of brain impulses are temporarily disturbed • Spectrum of symptoms • loss of consciousness for a few seconds to violent seizures • Idiopathic- Can be the result of injury • trauma, depressed skull fx, birth trauma or infection • Mildest- petit mal • children- brief loss of consciousness and mild muscular twitching- disappear in adolescent • Grand mal- generalized convulsions- • pt falls to floor, hypersalivates and losses control of urine and feces • An approaching seizure- aura, ringing in ear, tingling in fingers or spots before the eyes.Radiographic • Wait until patient is clinically stable • MRI to evaluate for a brain tumor • AVM or hippocampal sclerosis- most common cause for seizure that do not respond to therapy. • Otherwise CT/ MRI are normal Eight patients of all epileptic symptoms were cured by the team during the study. 

25. Degenerative Disease • Normal aging • Gradual loss of neurons- • enlargement of ventricular system and sulci • Alzheimer's • Presenile dementia- • diffuse form of progressive cerebral atrophy- • develop earlier than senile period • Huntington’s • Inherited- autosomal dominant- men • Early to middle adult- dementia • Choreiform movements- involuntary- rapid, jerky, continuous • Atrophy of caudate nucleus and putamen- focal dilation of frontal horns • Parkinson’s • Shaking palsy • Progressive- stooped posture, stiffness and slowness of movement • Basal ganglia • Enzyme defect resulting in inadequate production of neuronal transmitter dopamine (l-dopa) • Cerebellar atrophy • Inherited, degenerative or toxic effect of drugs as alcohol and phenytoin (Dilantin) • Lou Gehrig’s • Amyotrophic lateral sclerosis • Progressive – unknown cause • Atrophy and loss of motor nerve cells leading to extensive paralysis and death from respiratory weakness or aspiration pneumonia

26. Hydrocephalus • Dilation of the ventricular system • Increased intracranial pressure • Noncommunicating (obstructive) • Obstruction of CSF along the pathway • Enlarged lateral- normal 3rd- foramen of Monro • Enlarged lateral, 3rd- normal 4th-aquaduct of Sylvius • Enlarged system- Dandy Walker cyst at 4th vent • Communicating (nonobstructive)- more common • Generalized ventricular enlargement • Sulci normal or absent • Syndrome of gait ataxia, urinary incontinence, dementia are associated with ventricular dilation- with normal CSF pressure

27. Sinusitis • Paranasal sinuses • Maxillary, ethmoid, frontal, and sphenoid • Paired , air-filled cavities lined with mucous membrane • Size and shape vary in different age periods • Ethmoid- 6 yrs • Frontal- 10 yrs • Sphenoid- 2-3 and mature by adolescence • Viral infections cause upper respiratory obstruction with pain/ tender/ fever • Radiographic • Mucosal thickening • Water’s- patient erect- demonstrate air/ fluid levels • CT now modality of choice • MRI for complications such as mucocele, osteomyelitis and underlying intracranial dz