Lecture 8: Nervous System Flashcards
What systems make up the central nervous system?
The central and peripheral nervous systems
What makes up the central nervous system?
Brain and spinal cord
What makes up the peripheral nervous system?
12 pairs of cranial nerves, 31 pairs of spinal nerves, autonomic nerves and ganglia
What type of neurons make up the PNS?
Afferent (sensory) and Efferent (motor) neurons
What are afferent neurons?
Neurons that conduct impulses from peripheral receptors to the CNS
What are efferent neurons?
Neurons that conduct impulses away from the CNS to peripheral effectors
What is the somatic nervous system?
Nerves that supplies the striated skeletal muscles
What is the autonomic nervous system?
Nerves that supply smooth muscles, cardiac muscles and glandular epithelial tissues
What are types of CNS infections?
- Meningitis
- Encephalitis
- Brain abscess
- Subdural emphyma
- Epidural emphyma
- Osteomyelitis of the skull
What is meningitis?
An acute inflammation of the protective membranes covering the brain and spinal cord (meninges) - pia mater and arachnoid
What are the most common symptoms of meningitis?
Fever, intense headaches, vomiting and neck stiffness and occasional photophobia
How do infecting organisms of meningitis reach the meninges?
Infection in the middle ear, upper respiratory tract or frontal sinus, spread through the bloodstream or infection in the lungs
What is meningitis caused by?
Bacteria and viruses
What is the most common type of meningitis?
Bacterial meningitis (pyogenic)
What is encephalitis?
Viral inflammation of the brain and meninges
What are the cymptoms of encephalitis?
Ranges from mild headaches and fever to severe cerebral dysfunction, seizures and coma
What is one of the causes of encephalitis?
Herpes simplex virus
What is a brain abscess?
Usually a result of chronic infections of the middle ear, paranasal sinus or mastoid air cells or systemic infections (pneumonia, bacterial endocarditis, osteomyelitis)
What is subdural empyema?
A suppative 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 in the frontal or ethmoid sinuses
What are some other causes of subdural empyema?
Mastoiditis, middle ear infections, purulent meningitis, penetrating skull wounds, canietctomy or osteomyelitis of the skull
What is epidural empyema?
Infection outside the dural membrane and beneath the inner table of the skull
What is epidural empyema almost always associated with?
Ostepmyelitis in a cranial bone
Where do epidural empyema infections originate from?
From an infection in the ear or paranasal sinuses
What are the surgical interventions for epidural empyema?
Craniotomy, twist drill or burr holes
What is osteomyelitis of the skull?
A bone infection in the skull most commonly caused by direct extension of a supparative process form the paranasal sinuses, mastoid air cells or scalp
When do radiographic changes show in osteomyelitis of the skull?
1-2 weeks after the onset of clinical symtoms
What are CNS tumors?
- Glioma
- Meningioma
- Acoustic Neuroma
- Pituitary Adenoma
- Craniopharyngioma
- Pineal tumors
- Chordoma
- Metastases
What is the most common primary malignant brain tumor?
Glioma
What are glioma composed of?
Glial cells (supporting connective tissues in the CNS
What is the peak incidence of glioma?
Middle age adults, infrequent under 30 years
What are the types of gliomas?
- Glioblastoma
- Astrocytoma
- Oligodendeoglioma
- Ependymoma
- Medulloblastoma
What are the most common types of Glioma?
Glioblastoma and Astrocytoma
What is glioblastoma?
A highly agressive cancerous tumor that develops in the brain and forms in the shape of star shaped cells
What is astrocytoma?
The most common type of tumor that forms in your brain that can develop randomly
What is Oligodendrocytoma?
A CNS tumor that mostly affects the brain
What is ependymoma?
A growth of cells that form in the brain and spinal cords that form a tumor from ependymal cells
What are the ependymal cells responsible for?
Line the passageways that carry CSF
What is medulloblastoma?
A type of brain tumor that primarily affects children that originates in the cerebellum (responsible for coordination and balance)
What are the symtoms of medulloblastoma?
Headaches, nausea and problems with balance and coordination
What is glioblastoma multiforme?
A grade 4 glioma brain tumor that arises from glial cells
What is a tumors grade based on?
How likely the tumor is to grow and spread
What is the most aggressive and serious type of tumor
Grade 4
What is meningioma?
Tumor that grows from the membranes that surround the brain and spinal cord (meninges)
Why is a meningioma not classified as a brain tumor?
It forms in the head and not on the brain, but it can press on the brain, nerves and vessels
What is acoutic neuroma?
A slowly growing bening tumor that arises from Schwann cells in the vestibular portion of the auditory nerve
Where do acoustic neuroma usually originate?
In the internal auditory canal and entend into the cerebellopontine angle cistern
What is a pituitary adenoma?
A benign tumor that develops in the pituitary gland and affects pituitary hormone secretions
What is the most common type of pituitary adenoma?
Non-secreting chromophobe adenoma
What effect does non-secreting chromophobe adenoma have?
Mass effect tumor that supresses pituitary hormone secretions
What is hormone secreting pituitary adenoma?
Produce excess hormones causing gigantism in adults or acromegaly in children
What is craniopharygioma?
A benign tumor with both cystic and solid components usually nera the pituitary gland and hypothalamus
When is Craniopharyngioma usually seen?
Before the age of 20
Where are Craniopharyngioma most commonly located?
Above the sella turcica and depresses the optic chiasma
What are pineal tumors?
Tumors in the pineal gland with germinoma and teratoma being the most common types
Who are pineal tumors most common in?
Males younger than 25
What is chrodoma?
Tumors that arise from remnants of the notochord (the embryonic neural tube)
What are the most common sites of chordoma?
Clivus and lumbosacral region
What are metastases?
Cancers that spread to the brain from a different site of origin
What are the most common cancers to spread to the brain?
Lung and breast
What other cancers cause brain metatstases?
Melanomas, colon carcinomas, testicular and kidney tumors
What are traumatic processes of the CNS?
- Skull fracture
- Epidural hematoma
- Subdural hematoma
- Cerebral contusion
- Intracerebral hematoma
- subarachnoid hemorrhage
- carotid artery injury
- facial fractures
What are the types of skull fractures?
Linear, diastatic, and depressed
What are linear fractures?
Appear on plain radiographs as a sharp lucent line that is often irregular/jagged and occassionally branches
What are diastatic fractures?
A linear gracture that intersects a suture and couses along it, causing sutural separation
What is a depressed fracture?
Often stellate (start shaped) fracture lines that radiate outward from a central point
What is an epidural hematoma?
A collection of blood that forms between the skull and dura mater usually caused by acute arterial bleeding from a laceration
How do epidural hematomas usally appear?
As a biconvex peripheral, high density lesion
What is a subdural hematoma?
A collection of blood between the dura and other meninges usually caused by venous bleeding
How does a subdural hematoma usually appear?
On CT scans as a crescent shaped, peripheral zone of increase density
What is a cerebtal contusion?
An injury to the brain tissue caused by movement of the brain within the calvaria after blunt trauma to the skull
When do cerebral contusions occur?
When the brain contacts the rough skull surface
What are the types of traumatic brain injuries?
Direct impact injury
Acceleration-deceleration injury
Blast injury
What is an intracerebral hematoma?
A traumatic hemorrhage into the brain parenchyma that occurs at eht jungtion of gray and white matter
What is a subarachnoid hemorrage (SAH)
Bleeding into the ventricular systems due to injuries to surface veins, cerebral parenchyma or cortical arteries
What is the primary cause of a subarachnoid hemorrhage (SAH)?
Caused by a ruptured berry aneuysm
Where do subarachnoid hemorrhage tend to occur?
Contralateral to the site of direct impact
What is a diffuse axonal injury?
A form of traumatic brain injury that happens when the brain rapidly shifts inside the skill as an injury is occuring
What happens to the acons as a result of a diffuse axonal injury?
The axons are sheared as the brain rapidly accelerates and decelerates
What is a carotid artery injury?
Trauma to the extracerebral carotid arteries caused by penetrating trauma to the neck (gunshot or stabbing)
What are the types of facial fractures?
Blowout, tripod, Lefort, zygomatic arch and mandible fracture
Why are facial bones easily fractured?
They are thing bones with limited protection
Which facial bones are most commonly fractured?
Nasal bones
What are types of CNS vascular diseases?
- Stroke syndrome
- Transient Ischemic attacks
- Intraparencymal hemorrhage
- Subarachnoid hemorrhage
What is stroke syndrome?
A sudden and dramatic development of a focal neurological deficit (acute brain infarction)
How do stroke syndromes usually vary?
Vary from dense hemiplegia and coma to only trivial neurological disorders
What are the two main types of strokes?
Hemorrhagic and Ischemic strokes
What is a hemorrhagic stroke?
Caused by a blockage of one of the cerebral blood vessels
What is an ischemic stroke?
Caused by a blood vessel rupture and characterized by bleeding in the brain
What is a middle cerebral artery infarct?
A stoke that heppens when there is a blockage to the middle cerebral artery in the brain
What is a transient ischemic attack (mini stroke)?
Focal neurological deficits that resolve within 24 hours
What do TIA’s result from?
A brief blockage of blood flow to the brain and typically only lasts a few minutes and does not cause long-term damage
How many people who have a TIA will have a full stroke?
1 in 3
How many strokes are preceded by a TIA?
2/3
What is carotid artery stenosis?
A narrowing or construction of any part of the carotid arteries ususally caused by athersclerosis
What is intraparenchymal hemorrhage?
Hemorrhagic stroke caused by head trauma, hypertensive vascular disease, congenital berry aneurysm rupture or arteriovenous malformation
What is multiple sclerosis?
The most common demyelinating disorder that shows as recurrent attaches of focal neurologic deficits
What are the symptoms of MS?
Tremors, coordination issues, speech issues, vertigo, numbness, fatigue and weakness
What does MS primarily involve?
Spinal cord, optic nerve and central white matter of the brain
When are the peak incident of MS?
Between 20-40
What is the modality of choice for demonstrating MS?
MRI since it shows scatter plaques of dymyelination
What is epilepsy?
A condition in which the brain impulses are temporarily disabled
What are the symptoms of epilepsy?
Lack of consciousness, violent seizures
What are the two primary forms of epilepsy?
Petit mal and Grand mal
What is a petit mal seizure?
Mildest form of a seizure most commonly seen in children that diseapper into adulthood, that are bried episode of LOC and mild twitching
What are grand mal seizures?
Generalized convulsions associated with falling to the floor, hypersalivation and losing control of urine
What are degenerative diseases of CNS?
- Normal aging
- Alzheimers
- Huntington Disease
- Parkinson’s Disease
- Cerebellar Atrophy
- Amyotropic Lateral Sclerosis (ALS)
- Hydrocephalus
- Sinusitis
How is normal aging evidenced on imaging?
Enlargement of the ventricular systems and sulci caused by gradual loss of neurons
What are symtoms of normal aging?
Eye trouble, hearing loss, high blood pressure, decrease in mobility, agility and balance, decrease in muscle mass and stamina, high risk of accidents
What is alzheimer’s disease?
A diffuse form of progressive cerebral atrophy that develops at an earlier age than the senial period
What is alzheimer’s a form of?
Dementia
What modalities show alzeimer’s disease?
CR and MRI that show cerebral atrophy
What is Huntington’s disease?
An inherited condition primarily in men that presents in early to middle adult years causing dementia and jerky movements
What is a pathologic hallmark of Huntington’s disease?
Atrophy of the caudate nucleus and putamen
What is parkinson’s disease?
A progressive degenerative disease often called Shaking Palsy
What is parkinson’s disease characterized by?
Stooped posture, stiffness and slowness of movement, fixed facial expressions, involvuntary rhythmic tremor of the lims
When does parkinson’s disease usually show?
In middle or later life
What is cerebellar atrophy?
An isolated atrophy of the cerebellum
What is amyotrophic lateral sclerosis (ALS)?
Lou Gehrig’s disease that is characterized by widespread selective atrophy and loss of motor nerve cells
What does ALS result in?
Extensive paralysis and death from respiratory weakness
What is hydrocephalus?
A dilation of the ventricular system that is usually associated with increased intracranial pressure
What are the twp types of Hydrocephalus?
Non-communicating and communicating
What is non-communicating hydrocephalus?
An obstructive process in which CSF flow is blocked somewhere in its normal path
What is communicating hydrocephalus?
CSF flow into extraventricular subarachnoid space where it shouldn’t be cauing buildup and swelling
What is sinusitis?
Cuased by viral upper respiratory infections that obtructs draininage and causes pain, tenderness and swelling
How does sinusitis show radiographically?
As a soft tissue density lining the walls of the sinuses
What are most commonly affected by sinusitis?
Maxillary which can be visualized on a Water’s projection
