• 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
• 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
• 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
• 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
• 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
• 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
• 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
• Infection or inflammation can cause clots in cerebral veins or
venous sinuses
• Usually arise from ear, sinuses, scalp, nasal cavity, or the face
• 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
• 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 2nd
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
• 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
• 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
• 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
• Cerebellar lesions
cause tremor,
difficulty in
performing voluntary
movements
• Basal ganglia lesions
cause difficulty
initiating movement,
tremor or other
movements at rest,
rigidity
• 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
• Cerebral palsy – ante or perinatal lesion to a normal
nervous system impairs voluntary control,
hyperreflexia, symptoms like either basal ganglia or
cerebellar dysfunction
• 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
• Multiple sclerosis
– sensory, motor,
psychic
abnormalities
from an immunemediated attack
on central
nervous system
myelin that
leaves scars
called plaques
• Guillain-Barre
syndrome is
immune attack of
peripheral myelin
• 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
• Injury to the
spinal cord
interrupts
sensory, motor
pathways, with
increased
reflex activity
below the site
of the lesion
Amyotrophic lateral
sclerosis – loss of
corticospinal neurons
without any cognitive
impairment
• Autosomal recessive
disorders:
• Wednig-Hoffmann
disease – weakness –
floppy baby syndrome
• Wohlfart-KugelbergWelander disease - loss
of motor supply to
proximal muscles
• Friedrech’s Ataxia – thin
spinal cord affecting
movements
• Alzheimer disease
– progressive loss
of cortical
neurons,
degenerative
dementia that
affects all mental
function
• Biopsies show
neurofibrillary
tangles and
neuritic plaques
of amyloid
• 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
• 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
• 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
• 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
• 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
• Grand mal
status
epilepticus
(tonic-clonic
status) is
medical
emergency
• Acidosis,
increased
CO2, hypoglycemia
from muscle
contraction,
can lead to
death
• Evaluation of
tendency to have
seizures involves
routine EEG, CT,
MRI
drug therapy
with a single
anticonvulsant is
usual medical
management