Chapter 8 Nervous System
Terms in this set (69)
What does the Nervous system consist of?
central and peripheral systems
What does the Central Nervous System consist of?
What does the Peripheral Nervous system made up of?
-12 pairs of cranial nerves
-31 pairs of spinal nerves
The PNS is composed of two types of neurons and what are they?
afferent and efferent
conduct impulses from peripheral receptors to the CNS
(carries to brain)
conduct impulses away from the CNS to the peripheral effectors
(from brain to part affected)
Somatic nervous system
supplies the striated skeletal muscles
Autonomic Nervous system
supplies smooth muscle, cardiac muscle, and glandular epithelial tissue
is an acute inflammation of the pia mater and arachnoid
Meningitis can be caused by?
infection in the middle ear, upper respiratory tract or frontal sinus
spread through the bloodstream (hematogenously)
lung or other site infection in the lungs
can also be caused by bacteria and viruses
What is the most common form of meningitis?
Bacterial meningitis (pyogenic)
viral inflammation of the brain and meninges (meningencephalitis)
Encephalitis has what kind of symptoms?
wide range of symptoms
ranging from mild headache and fever to severe cerebral dysfunction, seizures and coma
The herpes simplex virus can cause what with Encephalitis?
a sudden, severe and fatal process
result of chronic infections of the middle ear, paranasal sinuses, or mastoid air cells, of systemic infections (pneumonia, bacterial endocarditis, osteomyelitis)
suppurative process in the space between the inner surface of the dura and the outer surface of the arachnoid
What is the most common cause of Subdural Empyema?
spread of infection from the frontal or ethmoid sinuses
What are the other causes of Subdural Empyema?
Middle Ear Infection
Penetrating Skull wounds
Osteomyelitis of skull
almost always associated with osteomyelitis in a cranial bone
Where does the Epidural Empyema originate from?
an infection in the ear or paranasal sinuses
Where does the Epidural Empyema infection occur ?
outside the dural membrane and beneath the inner table of the skull
What area of the brain is usually affected with Epidural Empyema?
the frontal region is usually affected because it is close to the frontal sinuses and the dura is easily stripped from the bone
Osteomyelitis of the Skull
is most commonly caused by direct extension of a suppurative process from the paranasal sinuses, mastoid air cells or scalp
radiographic changes develop 1 to 2 weeks after the onset of clinical symptoms and signs
are the most common primary malignant brain tumors
What is Glioma composed of?
glial cells (supporting connective tissues in the CNS)
How is Glioma spread in the brain?
by direct extension
can cross rom one cerebral hemisphere to the other through connecting white matter tracts, such as the corpus callosum
What is the peak age incidence for Glioma?
middle age adults
infrequent in persons less than 30 years of age
There are 2 types of Gliomas and what are they?
Astrocytomas- most common
There are less common types of Gliomas and what are they?
benign tumor that arises from arachnoid lining cells
attached to the dura mate
What are the most common sites of Meningioma?
-convexity of the calvaria
usually arise in the anterior lobe
What is the most common type of Pituitary Adenoma?
nonsecreting chromophobe adenoma
What does the mass effect of Pituitary Adenoma suppresses?
pituitary hormone secretions
Hormone-secreting pituitary adenomas produce what?
symptoms related to excess hormones, rather than mass effect
-Gigantism in adolescents
-Acromegaly in adults
What are the most common Pineal Tumors?
both are rapidly-growing germ cell tumors
most common in males under 35
(significant time of growth for males)
most common primary cancers to spread to the brain are
usually reach to the brain by hematogenous spread
What can cause brain metastasis?
Melanomas, colon carcinomas, and testicular and kidney tumors
appears on plain radiograph as sharp lucent line that is often irregular or jagged and occasionally branches
a linear fracture that intersects a suture and courses along it, causing sutural separation
-often stellate (star-shaped) with multiple fracture lines radiating outward from a central point
-when viewed en face, the fragment overlap makes the fracture line appear denser than the normal bone
-tangential views are required to determine the amount of depression
is caused by acute arterial bleeding, usually from a laceration to the middle meningeal artery
typically appears as a biconvex (lens-shaped), peripheral, high-density lesion
caused by venous bleeding
usually a vein between the dura and other meninges
appears on CT as a crescent shaped peripheral zone of increased density
follows the surface of the brain
lies adjacent to the inner table of skull
injury to brain tissue caused by movement of the brain within the calvaria after blunt trauma to the skull
-occurs when the brain contacts rough skull surfaces
-typically appear on CT scans as low-density areas of edema and tissue necrosis
-may or may not have mixed densities which indicate small, multiple hemorrhages
traumatic hemorrhage into the brain parenchyma
it results from shearing forces to intraparenchymal arteries
usually occurs at the junction of the gray and white matter
on CT, it appears as a well-circumscribed homogeneous, high density region often surrounded by low-density edema
bleeding into the ventricular system due to injury to surface veins, cerebral parenchyma or cortical arteries
CT shows increased density within the basilar cisterns, cerebral fissures, and sulk
MRI requires fluid-attenuated inversion recovery (FLAIR) sequence to demonstrate
Carotid Artery Injury
injured by penetrating trauma to the neck
associated with 50%percent of traumatic fistulas
thin bones with no protection
Nasal Bones are the most commonly fractured
What are the other types of Facial Fractures?
Zygomatic Arch Fracture
denotes the sudden and dramatic development of a focal neurologic deficit
also termed acute brain infarction
varies from dense hemiplegia and coma to only a trivial neurologic disorder
specific neurologic defect depends on the affected arteries
internal carotids are most commonly involved
Transient Ischemic Attacks (TIAs)
focal neurologic deficits that completely resolve within 24 hours
result from emboli originating from the surface arteriosclerotic ulcerated plaque (embolic stroke) or from stenosis of an extra cerebral artery
almost 2/3 of strokes are preceded by this
important to diagnose since 5 year cumulative risk of stroke in patients with this may be high as 50 percent
most common location is the region of the carotid bifurcation in the neck
termed hemorrhagic stroke
hypertensive vascular disease
congenital berry aneurysm rupture
hypertensive hemorrhages result in oval or circular collections that displace the surrounding brain and cause a significant mass effect
another form of hemorrhagic stroke
primary cause is a ruptured berry aneurysm
Multiple Sclerosis (MS)
most common demyelinating disorder
recurrent attacks of focal neurologic deficits
primarily involves the spinal cord, optic nerves, and central white matter of the brain
peak incidence is ages 20 to 40 years
strong predominance in women
clinical course is characterized by multiple relapses and remissions
MRI is the modality of choice for demonstrating this disease
What does MS look like on MRI?
scattered plaques of demyelination that demonstrate as multiple areas of increased signal intensity on T2-weighted images
condition in which brain impulses are temporarily disturbed
spectrum of symptoms ranging from loss of consciousness for a few seconds to violent seizures (shaking and thrashing movements of all extremities)
most cases of this disease are idiopathic
may be caused by head injury, birth trauma, or infection
There are two primary forms of epilepsy and what are they?
Petite Mal and Grand Mal
mildest form most commonly seen in children and generally disappears in young adulthood
brief episodes of loss of consciousness which may be associated with mild muscular twitching
generalized convulsions associated with the patient falling to the floor, hyper salivating (foaming at the mouth), and losing control of urine and sometimes feces
evidenced on images as enlargement of the ventricular system and sulk
caused by a gradual loss of neurons
diffuse form of progressive cerebral atrophy that develops at an earlier age than the senile period
CT and MRI demonstrate nonspecific findings of cerebral atrophy, including symmetrically enlarged ventricles with prominence of the cortical sulci
is an inherited (autosomal dominant) condition that predominately involves men
presents in early to middle adult years with dementia and typical chloroform movements (involuntary movements that are rapid, jerky and continuous)
What does Huntington's disease look like on CT?
atrophy of caudate nucleus and putamen
appearance of focal dilation of the frontal horns and a loss of their normal concave shape on CT images
generalized enlargement of the ventricles and dilation of the cortical sulk can also occur
the "shaking palsy" is a progressive, degenerative disease
stiffness and slowness of movement
fixed facial expression
involuntary rhythmic tremor of the limbs that disappears with voluntary movement
shows up in middle or later life
gradually progressive and exhibits a prolonged course
isolated atrophy of the cerebellum
an inherited disorder
toxic effect of prolonged use of such drugs as alcohol and phenytoin (Dilantin)
Amyotrophic Lateral Sclerosis (ALS)
Lou Gehrig's disease
characterized by widespread selective atrophy and loss of motor nerve cells (movement)
death is usually from respiratory weakness or aspiration pneumonia
dilation of the ventricular system that is usually associated with increase intracranial pressure
pattern of ventricular enlargement and other characteristics seen on images help in identifying type or location of obstruction
Two types of Hydrocephalus
-CSF flow blocked somewhere in its normal pads
CSF flows into extraventricular subarachnoid space
caused by a viral upper respiratory infections
localized pain, tenderness and fever
radiographically appears as a soft tissue density lining the walls of the involved sinuses
maxillary are the most infected
(best visualized on waters)
an air fluid level in a sinus is usually considered a manifestation of acute inflammatory disease