Transcript Neuro - Quia

Neurosurgery
Neuron- nerve cell

Dendrite
One or more
Conducts
impulses toward
the cell body

Axon
Conducts
impulses away
from the cell body
Synapse
Space between
the junction of two
neurons
Neurotransmitter
Substance that is
released when the
axon is excited
Travels across the
synapse to the
target cell



Norepinephrine
Acetylcholine
Dopamine
Myelin
The phospholipidprotein of the cell
membranes of
Schwann
(neuroglia) cells
which forms a
sheath around
neurons
Myelin, cont.
Acts as an
insulator to support
and protect the
nerve cell, and to
increase the
velocity of impulse
transmission
Gray Matter
Nerve tissue
composed mainly
of the cell bodies
of neurons, rather
than their
myelinated
processes
Gray Matter, cont.
Term is generally
applied to the gray
portions of the
central nervous
Gray Matter, cont.
Cerebral cortex
Basal ganglia
Gray columns of
the spinal cord
which forms an Hshaped region
surrounded by
white matter
White Matter
The white
substance of the
spinal cord and
brain, consisting
principally of
myelinated nerve
axons
The Nervous System
The Nervous System
Central nervous
system

Consists of the
brain and the
spinal cord
Peripheral
nervous system

Consists of the
cranial and spinal
nerves
The Nervous System
Divided
functionally into:


Voluntary
Autonomic
(involuntary)
Sympathetic
Parasympathetic
The Nervous System
Functions include:

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



Orientation
Coordination
Conceptual
thought
Emotion
Memory
Reflex response
Cranial Sensation
The only pain sensitive structures that
cover the brain are:



The scalp
Extracranial arteries
Portions of the dura mater
The brain itself is insensate
Scalp
Layers include:


Skin
Subcutaneous
tissue



Galea
Subgaleal space
Pericranium
Scalp, cont.
Skin

Tends to be thick
Subcutaneous
tissue


Dense, tough,
vascular
Attached to the
galea
Scalp, cont.
Galea


Tough, fascia
like tissue
covering the
cranium
Connects
muscles to the
temples,
forehead, and
base of the skull
Scalp, cont.
Subgaleal space



Loose areolar
tissue
Permits mobility of
the scalp
Bloodless plane,
used in standard
craniotomy flap
Scalp, cont.
Pericranium


Periosteum of the
skull
Separates the galea
from the cranium
Arterial supply for
the scalp

From branches of
the external carotid
artery
Skull
Formed by 24 bones, joined by serrated
bony seams called sutures
Skull, cont.
8 bones form the walls of the cranial
cavity which houses the brain
Skull, cont.

4 single bones
frontal, occipital, ethmoid, and sphenoid
Skull, cont.

2 paired bones
temporal and parietal
Skull, cont.
Consists of
flattened irregular
shaped bones,
comprised of 2
tables of compact
bone enclosing a
layer of spongy
bone
Cranial Fossae
Interior
anatomically
divided into 3
cranial fossae:

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
Anterior
Middle
Posterior
Foramen Magnum
Largest opening
in the skull
Permits the
spinal cord to
join with the
brainstem
Major sutures of the skull
Coronal

Joins the frontal
and parietal bones
Squamous

Borders the
squamous part of
the temporal bone
Major sutures of the skull, cont.
Major sutures of
the skull

Lambdoid
Joins the occipital
and parietal
bones

Sagittal
Joins the two
parietal bones in
the median plane
Fontanelles
Anterior and posterior
Located at the top of the skull in front of
and behind the parietal bones
Both are open at birth
Fontanelles, cont.
Posterior is generally closed by 2 months
Anterior is generally closed by about 18
months
Meninges
Three (3)
membranous
layers between
the brain and the
skull
"The meninges
P.A.D. the brain.“

Pia; Arachnoid;
Dura.
Meninges
Dura Mater

Tough shiny fibrous
outermost membrane
Arachnoid

Middle layer, fine
membrane
Pia Mater

Innermost
membrane, like
gossamer
Dura Mater
Tentorium Cerebelli


A transverse fold of dura forming the roof of
the posterior fossa
Supports the temporal and occipital lobes of
the cerebral hemispheres.
Supratentorial

Structures above the tentorium
Infratentorial

Structures below the tentorium
Dura Mater
Falx cerebri

A fold of the dura
mater that lies in
the longitudinal
fissure and
separates the
two cerebral
hemispheres
Falx Cerebri
Dura Mater
Falx cerebelli

A fold of the dura mater that forms a vertical
partition between the hemispheres of the
cerebellum
Venous sinuses

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Lie at the margins of the dural folds
Drain blood from the intracranial structures
into the jugular veins
Dura Mater
Venous sinuses


Venous
channels found
between the
layers of the
dura mater
They receive
blood from
internal and
external veins of
the brain and
ultimately empty
into the internal
jugular vein.
Arachnoid
Outer surface of the arachnoid membrane
adheres closely to the dura, with no space
normally between the 2 membranes
The inner surface of the arachnoid is
separated from the pia mater beneath it
by the subarachnoid space, which is filled
with CSF
Pia Mater
Attaches to the gray matter and dips into
the sulci and gyri
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Sulci- furrow, groove,
or slight depression
Gyri- convolutions
Fissures- deeper grooves
Has a rich vascular network that helps
form the choroid plexus of the ventricles
Brain
Cerebrum

Largest part of the brain
Midbrain
(mesencephalon)

Between the cerebral
hemispheres and the pons
Brainstem
(hindbrain)

Immediately below the
midbrain
Brain
Encephalon

The brain
Diencephalon

2nd portion of the
brain, or
interbrain
(deep structures)
Cerebrum
Divided into right and left cerebral
hemispheres by a longitudinal fissure
Cerebrum, cont.
Each hemisphere controls sensation and
motor activity to and receives sensory
stimuli from the opposite half of the body
Cerebrum, cont.
Each hemisphere is divided into frontal,
parietal, occipital and temporal lobes, insula,
rhinencephalon, basal ganglia, thalamus
and hypothalamus
Frontal lobe
Higher mental
functions of
intellect
Abstract
reasoning
Parietal lobe
Make sense of
speech and
formulate words
with emotional
content
Hearing and the
ability to
understand
speech
Parietal lobe, cont.
Interpret sensory
information
Read printed
words
Visual memory
Music
Occipital lobe
Posterior to the
parieto-occipital
fissure
Receives and
integrates visual
impulses and
registers them as
meaningful
images
Temporal lobe
Comprehension
and verbalization
of words
Insula
a.k.a. Island of Reil
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Central lobe of the cerebral hemisphere
Triangular area of the cerebral cortex lying in
the floor of the lateral fissure
Concerned with autonomic functions
Insula, cont.
Processes convergent information to produce
an emotionally relevant context for sensory
experience
Has an important role in pain experience and
the experience of a number of basic emotions,
including anger, fear, disgust, happiness and
sadness
Imaging studies have also implicated the insula
in conscious desires, such as food craving and
drug craving
Rhinencephalon
Near the sphenoid bone

Receives and integrates olfactory impulses
Basal Ganglia
Four masses of gray matter located
deep in the cerebral hemispheres
Basal Ganglia, cont.
Contribute to some
of the subconscious
aspects of voluntary
movement
Initiate stimuli for
movement and
provide essential
links in complex
motor circuits
Thalamus
Ovoid, gray
nuclear mass in
the lateral wall of
the 3rd ventricle
Is part of the
diencephalon
Intimately
connected to the
pituitary gland
Thalamus, cont.
All sensory stimuli,
with the exception
of olfactory, are
received,
associated,
integrated, and
relayed to the
specific cortical
areas
Hypothalamus
Activates, controls
and integrates the
peripheral
autonomic nervous
system, endocrine
processes, and
many somatic
functions such as
body temperature,
sleep and appetite
Sulci and Gyri
Surface of the hemispheres form
convolutions called gyri and
intervening furrows called sulci.
Lateral sulcus
a.k.a. fissure of Sylvius
Marks off the temporal lobe.
Central sulcus
A.K.A. Fissure of Rolando
Separates the motor from the sensory cortex
Central sulcus, cont.
Anterior to central sulcus is the motor area,
controlling voluntary motor function
Central sulcus, cont.
Posterior to the central sulcus is the sensory
area, which receives sensory impulses
Midbrain
A.K.A.
Mesencephalon
Between the
cerebral
hemispheres
and the pons
Connects the
pons and the
cerebellum with
the hemispheres
of the cerebrum
Midbrain, cont.
Contains reflex
centers for eye
and head
movements in
response to
visual and
auditory stimuli
Controls the
majority of eye
movements
Brainstem
A.K.A. hindbrain
Immediately below
the midbrain
Consists of the
Pons and the
Medulla
Oblongata
Surgery here is
very dangerous
Pons
Origin of cranial
nerves V, VI, VII,
and VIII
Relays sensory
information between
the cerebellum and
cerebrum
helps regulate
respiration
Medulla Oblongata
Origin of cranial
nerves IX, X, XI,
and XII
Controls
cardiovascular
and respiratory
regulatory
centers
Cerebellum
Occupies most of the posterior fossa
Has 2 lateral lobes and a medial portion
called the vermis
Cerebellum, cont.
Principally concerned with balance and
coordination of movement
Cerebrospinal fluid
A.K.A. CSF
Clear and colorless
fluid
Much of it
originates in the
choroid plexuses
of the ventricles
Bathes the brain
and spinal cord
Cerebrospinal fluid functions
Helps support the
weight of the brain
Acts as a cushion for
the brain and spinal
cord by absorbing
some of the force of
external trauma
Keeps intracranial
pressure (ICP)
constant by variations
of volume
Ventricles
Four
communicating
cavities filled
with CSF
Lateral ventricles (2)
One lying in each
cerebral hemisphere
Each has a body
and three hornsfrontal, occipital,
and temporal
Drains into the
foramen of Monro
(aka interventricular
foramen)
Third ventricle
Centrally located
below the bodies of
the lateral ventricles
Communicates
anteriorly with the
lateral ventricles
through the foramen
of Monro
Third ventricle, cont.
Communicates
posteriorly with the
fourth ventricle
through the
aqueduct of Sylvius,
a long narrow
channel passing
through the
midbrain
Fourth ventricle
In the posterior
fossa between the
cerebellum and the
brainstem
CSF escapes into
the subarachnoid
space via the
foramen of
Magendie and the
two foramina of
Luschka
Brain blood supply
Brain requires 20%
more O2 than any
other organ, and
utilizes glucose as
its chief source of
energy
The brain normally
receives 20% of
cardiac output
Brain blood supply, cont.
Internal carotid
arteries (2)

Anterior
Vertebral arteries
(2)

Posterior
Brain blood supply, cont.
Communicate at
the base of the
brain through the
circle of Willis
Ensures continuity
of circulation if any
one of the four
main channels is
interrupted
Brain blood supply, cont.
Cerebral veins
do not parallel
the arteries
Located in the
meninges and
the deep cerebral
veins
Cranial Nerves- 12 pairs
On Old Olympus'
Towering Top A Finn
And German Viewed
Some Hops
Oh Oh Oh To Touch
And Feel Very Good
Velvet, Ah Heaven
Oh, Oh, Oh, To Touch
And Feel Very Good
Velvet. Such Heaven
Cranial Nerve I (#1)- Olfactory
Sense of smell
You only have one
nose…
Cranial Nerve II (#2)- Optic
Sense of sight
…but you have
two eyes
Cranial Nerve III (#3)Oculomotor
Controls four
extrinsic eye
muscles (except
the lateral rectus
and superior
oblique)
Controls the
intrinsic muscles
(cilliary and iris)
Cranial Nerve IV (#4)- Trochlear
Controls the
superior oblique
eye muscle
Cranial Nerve V (#5)- Trigeminal
Sensory supply to
the head, face,
nose, and mouth,
and the motor
intervention for the
muscles of
mastication
(chewing)
Cranial Nerve VI (#6)- Abducens
Controls the lateral
rectus muscle of
the eye
“Abducts” the eye
Cranial Nerve VII (#7)- Facial
Controls
superficial
muscles of the
face and scalp,
and the anterior
two thirds of the
tongue for taste
Cranial Nerve VIII (#8)- Acoustic
A.K.A.
Vestibulocochlear
Cochlear branch
for hearing and a
vestibular branch
for balance
Cranial Nerve IX (#9)Glossopharyngeal
Taste and
sensations of the
tongue, swallowing,
secretions of saliva,
and pharyngeal
muscles (partially)


Glosso- Tongue
PharyngealPharynx
Cranial Nerve X (#10)- Vagus
Innervation of
pharyngeal and
laryngeal
musculature,
control of heart
rate, regulation of
acid secretions in
the stomach, and
peristalsis
Cranial Nerve XI (#11)- Spinal
Accessory
Motor nerve to the
sternocleidomastoid
and trapezius
muscles
Called either Spinal
Accessory or just
Accessory
Cranial Nerve XII (#12)Hypoglossal
Motor nerve for the
tongue


Hypo- below
Glossal- tongue
Cranial Nerves- Recap
Spinal Column
Consists of 33
vertebrae

7
7 cervical

12 thoracic

5 lumbar
12
5


5 sacral
4 coccygeal
5
4
Cervical (C1 to C7)
1st - the atlas

Supports the skull
2nd – the axis

Ligaments hold
the 1st and 2nd
together but allow
for considerable
rotational
movement
Thoracic (T1 to T12)
Distinguished by
the presence of
costal facets for the
articulation of the
heads of ribs
Body is
intermediate in size
between the
cervical and lumbar
vertebrae
Lumbar (L1 to L5)
Body
Spinous
process
Transverse
process
Lamina
Articular facets
Intervertebral disc
Fibrocartilaginous cushion separating one
vertebral body from another
Can herniate
Sacrum (S1 to S5)
Fused as one
large triangular
shaped bone
Articulates with
L5, Co1 and the
two pelvic bones
Coccyx (Co1 to Co4)
Fused as one
A.K.A. tailbone
Spinal cord
Develops from
the embryonic
neural tube
Covered by the
meninges
Passes through a
central canal in
the spinal column
to the level of the
1st or 2nd lumbar
vertebrae
Spinal cord, cont.
Blood supply is
from the vertebral
arteries
Cauda equina

Collection of
spinal roots from
the inferior
(terminal) spinal
cord which
resembles a
horses tail
Spinal Nerves
31 pairs
2 pairs of spinal
nerves exit at
each vertebral
level


Anterior motor
root
Posterior
sensory root
Pathology
Craniosynostosis
Premature
ossification of the
sutures (and
fontanelles) of the
skull.
The skull cannot
expand as the brain
grows, so it may
require surgical
intervention.
Pre-op
Post-op
Hydrocephalus
Condition characterized by abnormal
accumulation of CSF within the cranial
vault with subsequent dilation of the
ventricles
Hydrocephalus, cont.
Results from an increase in CSF
production or a decrease in CSF
absorption
Hydrocephalus, cont.
TX- surgical
intervention to correct
the obstruction, reduce
production, or shunt
the excess fluid to the
right atrium or to the
peritoneal cavity
Intervention has about
an 80% success rate
Meningitis
Infection or inflammation of the meninges
May elevate CSF pressure
Encephalitis
Inflammatory condition of the brain
May elevate CSF pressure
Meningocele
Sac like protrusion
of the meninges
through a
congenital defect in
the skull or spinal
column
Forms a herniated
cyst filled with CSF,
but does not
contain neural
tissue
Spina Bifida
A congenital
defect in the
walls of the
spinal canal
caused by a
lack of union
between the
lamina of the
vertebrae
Spina Bifida, cont.
Commonly
lumbar
Membranes
of the cord
are pushed
through the
opening if it
is wide
enough
Spina Bifida, cont.
Contents of
the spinal
canal may
protrude
Relatively
common

10-20 per
1000 live
births
AV Malformation
Thin walled vascular channels that
connect arteries and veins without the
usual intervening capillaries
AV Malformation, cont.
May be microscopic or massive
Fistulas may be congenital, or may result
from trauma or disease
AV Malformation, cont.
Difficult to treat successfully



Feeding vessels can be clipped
Total removal gives the best results
Laser and Gamma Knife have been
successful
Trigeminal Neuralgia
Disorder of the
trigeminal (fifth)
cranial nerve
Causes episodes of
intense, stabbing,
electric shock-like
pain along one or
more of it’s branches,
but usually along the
maxillary nerve
Trigeminal Neuralgia, cont.
Also called “tic
douloureux”
because it’s often
accompanied by a
brief facial spasm or
tic
Most frequently
occurring of all the
nerve pain disorders
Trigeminal Neuralgia, cont.
Episodes last from
seconds to 2
minutes in duration
Cause is thought to
be pressure from
blood vessels on
the trigeminal nerve
root
Trigeminal Neuralgia, cont.
Treatment options
include:


Medications
Microvascular
Decompression
Surgery
Placement of Teflon
pad between vessel
and nerve root
Considerations
Hemostatic agents





Bone wax
Scalp clips
Cottonoids
Gelfoam and
topical thrombin
Bipolar and
monopolar
cautery
Considerations
Hair may be removed with electric
clippers, then shaved

Hair is considered the patients property and
is placed in a specimen container, labeled
and documented on the operative record
Considerations
Headrest or skull clamp may be used for
positioning
Considerations
Positioning
varies depending
upon surgical
approach, and
may include
prone, lateral,
supine, or sitting
Considerations
Patient may be positioned on a
hypothermia mattress to reduce cerebral
blood flow and venous pressure, and to
decrease blood volume and ICP
Air embolism is a potential problem when
the sitting position is used.


Brain is higher than the heart.
Venous pressure may be lower than
atmospheric and can allow for air entry into
open venous channels
Considerations
Incision site may be
marked prior to the
prep, or after the prep
and prior to draping
Mayfield or similar
table may be used for
cranial procedures
Considerations
Prevent sudden movement around the
surgeon and bumping of the OR table or
microscope, as slips can be fatal
Considerations
Irrigation must be warm (body temperature)
to prevent shock to the brain or nerves

Warming basins are available
Microscope may have a camera attached
to allow for anticipation
Anesthesia may be local or general for
craniotomy
Surgical interventions
Surgical interventions
Burr Holes
(Trephination)
Craniectomy
Craniotomy
Intracranial Aneurysm
AV Malformation
Transsphenoidal
Hypophysectomy
Cranioplasty
Stereotaxis
Ventriculoatrial Shunt
Ventriculoperitoneal
Shunt
Laminectomy
Anterior Cervical Fusion
Carotid Artery Ligation
Sympathectomy
Nerve Repairs
Carpal Tunnel Syndrome
Ulnar Nerve
Transposition
Burr holes (trephine)
Perforator - cranial burr
Placed to remove a localized collection of
fluid beneath the dura
May be used to tap a ventricle, or to drain
or treat an abscess
Craniectomy
Incision into the skull and removal of
bone by enlarging one or more burr
holes
Craniotomy
Incision into the
skull
Use a craniotome
to make burr
holes, then
“connect the dots”
Craniotomy, cont.
Bone flap may be
left attached or
removed (free)
Bone flap should
be wrapped in a
moist sponge
Craniotomy, cont.
Moist cottonoid strips and bone wax
control bleeding
Dura hook, #11 blade, and dura scissors
4-0 Neuralon on fine needles for
retraction and closure of the dura
Craniotomy, cont.
Moist cottonoids and strips help prevent
air emboli
Frequent irrigation to prevent drying of the
brain tissue
Procedure of choice done, depending
upon pathology
Craniotomy, cont.
Bone flap may not be replaced if swelling
is anticipated, but may be preserved for
later use
Always hold the bone flap with two hands
Bone flap may be placed using wires or
plates and screws
Intracranial aneurysm
Vascular dilation
usually caused by a
local defect in the
arterial wall
Hemorrhage into the
subarachnoid space,
causing sudden,
severe headache, is
usually the first sign
Intracranial aneurysm, cont.
Fatal hemorrhage is the
greatest hazard of this
condition, and of the
operation
Aneurysm clips are
frequently used, and
should only be opened
using their applying
forceps, and only once
Transsphenoidal Hypophysectomy
Removal of pituitary gland
tumors through a
transsphenoidal approach
Tumors are usually
benign, and are often
responsible for
overproduction of specific
pituitary hormones
Transsphenoidal Hypophysectomy
Incision is made in the
upper gum margin (or may
be through the nasal
cavity), nasal mucosa is
elevated, floor of the
sphenoid sinus is removed,
and floor of the sella
turcica is entered
Transsphenoidal Hypophysectomy
Performed under general
anesthesia, semi-sitting
position
An ENT surgeon may
enter and close the cavity
Cranioplasty
Repair of skull defects resulting from
trauma, malformations, or a surgical
procedure
May use bone, cartilage, celluloid, metals,
synthetic resins such as methyl
methacrylate and silicone rubber
Stereotaxis
Accurate location of a definite
circumscribed area within the brain from
external points or landmarks on the skull
Defines 3 dimensional coordinates
(planes) by which to approach deep
structures without damaging overlying
structures
Stereotaxis, cont.
Performed under local anesthesia
The patients head is placed in a
stereotaxic frame
Uses CT, MRI or PET to locate target site
May use lasers, cryotherapy, radiation,
etc.
Ventriculoatrial or
Ventriculoperitoneal Shunt
Excess CSF drained
to the right atrium of
the heart or
Peritoneal cavity
Performed for
treatment of
hydrocephalus
Ventriculoatrial or
Ventriculoperitoneal Shunt
Multi-holed ventricular
catheter placed via a
burr hole
Reservoir and valve
system directs CSF
away from the
ventricles
Distal draining tube
Laminectomy
Removal of one or
more vertebral
laminae to expose
the spinal canal
Performed for
herniated disk,
compression
fracture, cord
tumors, etc.
Laminectomy, cont.
Can be performed
in the prone
(lumbar), lateral or
knee-chest
(thoracic), sitting
(cervical), or
supine
Spinal needle and
x-ray used to
check position
Laminectomy, cont.
Use a moist
sponge to remove
tissue from the
rongeur


Bone- is
discarded at most
hospitals
Disc- is saved and
sent to pathology
as a specimen
Anterior cervical disk with fusion
(ACF)
AKA Cloward procedure
Removal of the disk and fusion of the
cervical bodies
Supine position, head turned slightly to
the left, and right hip elevated
Bone graft is taken from the iliac crest
Carotid artery ligation
Performed to occlude the internal carotid
artery
Performed to control anticipated
hemorrhage during intracranial surgery for
vascular anomalies
Permanent occlusion may be performed
to control intracranial hemorrhage or for
small, repeated strokes from an
intracranial lesion
Sympathectomy
Excision of a portion of the sympathetic
division of the autonomic nervous system
Performed to treat intractable pain from
certain debilitating nerve injuries, or
chronic abdominal conditions (vagotomy)
Position, approach, and instrumentation
depends upon area to be resected
Nerve repairs
For peripheral nerve injuries
Recovery will occur only if regeneration of
nerve axons takes place from healthy
proximal segments
Nerve stimulator and microscope may be
used
Carpal tunnel syndrome
Compression of the median nerve
Release of the carpal ligament
decompresses the nerve
Usually performed as an open procedure,
but may be done endoscopically
Ulnar nerve transposition
At the elbow
Performed for traumatic or anatomic
problems that irritate it, causing chronic
discomfort
Dissect the nerve free and relocate the
nerve to a more anterior position
You have now reached the
END of the Neuro
presentation!
Have a Great Day! 