SCHWARTZ Ch42 - Neurosurgery Flashcards
Neurologic and Neurosurgical Emergencies
1) Raised ICP
2) Brain Stem Compression
3) Stroke
4) Seizure
Normal ICP
4-14mmHg
Sustained ICP level that can injure the brain
20 mmHg
3 normal contents of the
cranial vault:
1) Brain tissue (80%)
2) Blood (10%)
3) CSF (10%)
Brain’s content expand due to:
1) swelling from traumatic brain injury (TBI)
2) Stroke
3) reactive edema
Blood volume can increase by:
1) Extravasation to form hematoma
2) reactive vasodilation in a hypoventilating, hypercarbic patient
CSF volume increases by:
Hydrocephalus
Temporal lesions push
the uncus medially and compress the midbrain.
uncal herniation
Masses higher up in the
hemisphere can push the cingulate gyrus under the falx cerebri
subfalcine herniation
passes between the uncus and midbrain and may be
occluded, leading to an occipital infarct.
posterior cerebral artery
PCA
the branches of this artery run along the medial surface of
the cingulate gyrus
anterior cerebral artery (ACA)
posterior cerebral artery
PCA
leading to an occipital infarct.
anterior cerebral artery (ACA)
leading to
medial frontal and parietal infarcts.
Cushing’s triad
hypertension, bradycardia, and irregular respirations.
increased ICP, or intracranial hypertension,
often will present with..
- headache
- nausea
- vomiting and
- progressive mental status decline
Initial management of intracranial hypertension
airway protection and adequate ventilation
a characteristic “crashing patient,”
- rapidly loses airway protection,
- becomes apneic,
- and herniates.
The cingulate gyrus shifts across midline
under the falx cerebri
Subfalcine herniation
The uncus (medial temporal lobe gyrus) shifts medially and compresses the midbrain and cerebral peduncle
Uncal herniation
The diencephalon and midbrain shift caudally through the tentorial incisura.
Central transtentorial herniation
The cerebellar tonsil shifts caudally
through the foramen magnum.
Tonsillar herniation.
posterior fossa
brain stem and cerebellum
Symptoms of brain stem
compression include:
-hypertension
-agitation
-progressive
obtundation
-followed rapidly by brain death
brain stem compression management:
emergent neurosurgical
evaluation for possible ventriculostomy or suboccipital craniectomy
defined as an uncontrolled synchronous organization of neuronal electrical activity
seizure
three main areas of neurosurgical
focus for trauma are:
1) traumatic brain injury (TBI)
2) spinal cord injury (SCI)
3) peripheral nerve injury
most common type of cerebral hernia
Subfalcine hernia
Subfalcine hernia
also known as midline shift or cingulate hernia
caused by unilateral frontal, parietal, or temporal lobe disease that creates a mass effect with medial direction, pushing the ipsilateral cingulate gyrus down and under the falx cerebri
Subfalcine hernia
the movement of brain tissue from one intracranial compartment to another. This includes uncal, central, and upward herniation
Transtentorial herniation
Neurological signs that reflect dysfunction distant or remote from the expected anatomical locus of pathology
false localizing signs
The initial assessment of the
trauma patient includes
- primary survey
- resuscitation
- secondary survey
- definitive care
GCS Motor score
1 to 6
GCS Verbal score
1 to 5
GCS eye score
1 to 4
Normal GCS range
3-15
this fracture
is covered by intact skin
closed fracture
fracture is
associated with disrupted overlying skin
An open, or compound, fracture
The fracture lines may
be
- single (linear);
- multiple and radiating from a point (stellate);
- multiple, creating fragments of bone (comminuted)
Closed
skull fractures do not normally require specific treatment
Open
fractures require repair of the scalp and operative debridement
Indications for craniotomy
-depression greater than the cranial thickness, -intracranial hematoma, -frontal sinus involvement
Depressed skull fractures may result from
a focal injury
of significant force
GCS range for intubated patients
3T to 10T
simple laceration
copiously irrigated and closed primarily
laceration is short, a single-layer
percutaneous suture closure
laceration is long or has multiple arms
patient may need debridement and closure in the operating room, with its superior lighting and wider selection of instruments and suture materials
Extravasation of
blood results in ecchymosis behind the ear,
Battle’s sign
fracture of the anterior skull base can result in
1) anosmia (loss of smell from damage to the olfactory nerve), 2) CSF drainage from the nose (rhinorrhea),
3) periorbital ecchymosis,
(raccoon eyes)
A fracture of the temporal bone, for
instance, can damage the facial or vestibulocochlear nerve,
resulting in
vertigo, ipsilateral deafness, or facial paralysis
a carbohydrate-free isoform of transferrin exclusively found in
the CSF
β-2 transferrin testing
this test assesses for a double ring when a drop of the fluid is allowed to fall on an absorbent surface
The “halo” test
when the CSF leak is
in the lumbar thecal sac
the head of the bed should be flat so as to maximize hydrostatic pressure of the CSF fluid column at the cranial vault, away from the site of the defect
When
there is a contraindication, to lumbar drain placement
an extraventricular
drain should be used for CSF diversion
The initial impact, defined as the immediate injury to
neurons from transmission of the force of impact
primary injury
Subsequent neuronal damage due to the sequelae of trauma is referred to as
secondary injury
mechanisms of secondary injury
- Hypoxia,
- hypotension,
- hydrocephalus,
- intracranial hypertension,
- thrombosis,
- intracranial hemorrhage
ABCD of resucitation
airway
breathing
circulation
disability
severe head injury
GCS score is 3 to 8
moderate head injury
GCS score is 9 to 12
mild head injury
GCS score is 13 to 15
TBI patients who are asymptomatic, who have only
headache, dizziness, or scalp lacerations, and who did not lose consciousness
low risk for intracranial injury
Patients with a history of altered consciousness, amnesia, progressive headache, skull or facial fracture, vomiting, or
seizure
moderate risk for intracranial injury
Patients with depressed consciousness, focal neurologic
deficits, penetrating injury, depressed skull fracture, or changing
neurologic examination
high risk for intracranial injury
may be discharged home without a head CT scan
low risk for intracranial injury
undergo a prompt head CT
moderate risk for intracranial injury
Types of Closed Head Injury
Concussion
Contusion
Diffuse Axonal Injury
Penetrating Injury
Colorado grading system
Concussion
Colorado grading system:
Head trauma patients with confusion
grade 1
Colorado grading system: patients with amnesia
grade 2
Colorado grading system: patients who lose consciousness
grade 3
The brain is also much more susceptible to injury from
even minor head trauma in the first 1 to 2 weeks after concussion. Patients should be informed that, even after mild head injury, they might experience memory difficulties or persistent headaches.
second-impact syndrome
temporary neuronal
dysfunction following nonpenetrating head trauma; head CT is normal, and deficits resolve over minutes to hours
concussion
defined as:
- transient loss of consciousness,
- alteration of mental status.
- Memory difficulties
- amnesia of the event
concussion
a bruise of the brain, and occurs when the force from trauma is sufficient to cause breakdown of small vessels and extravasation of blood into the brain
contusion
frontal, occipital, and temporal poles are most often involved
contusion
Contusions also may occur in brain tissue opposite the site of impact. These contusions result from deceleration of the brain against the skull
contre-coup injury.
caused by damage to axons throughout the brain, due to rotational acceleration and then deceleration
Diffuse axonal injury (DAI)
considered to be a severe
form of a concussion, often with irreversible consequence.
Diffuse axonal injury (DAI)
due to bullets or fragmentation devices
missile (Penetrating Injury)
due to knives or ice picks
nonmissile (Penetrating Injury)
Traumatic Intracranial Hematomas
1) Epidural Hematoma
2) Acute Subdural Hematoma
3) Intraparenchymal Hemorrhage
4) Pneumocephalus
accumulation of blood
between the skull and the dura
Epidural Hematoma
results from arterial disruption, especially of the middle meningeal artery
Epidural Hematoma
Epidural Hematoma on head CT
the blood clot is bright,
biconvex in shape (lentiform), and has a well-defined border
that usually respects cranial suture lines
result of an accumulation of blood between the arachnoid membrane and the dura
Acute Subdural Hematoma
results from venous bleeding, typically from tearing of a bridging vein running from the cerebral cortex to the dural sinuses
Acute Subdural Hematoma
Acute Subdural Hematoma on head CT
the clot is bright or mixed-density, crescent-shaped (lunate), may have a less distinct border, and does
not cross the midline due to the presence of the falx
Open craniectomy for evacuation of the congealed clot and
hemostasis generally is indicated for EDH.
- clot volume <30 cm3
- maximum thickness <1.5 cm, –GCS score >8
Open craniotomy for evacuation of acute SDH is indicated
for any of the following:
-thickness >1 cm
-midline shift >5 mm
-GCS drop by two or more points from the time of injury to
hospitalization
a collection of blood breakdown products that is at least 2 to 3 weeks old
Chronic Subdural Hematoma
Chronic Subdural Hematoma on head CT
Acute hematomas are bright white (hyperdense) on CT scan for approximately 3 days, after which they fade to isodensity with brain, and then to hypodensity after 2 to 3 weeks. A true chronic SDH will be nearly as dark as CSF on CT
Traces of white
are often seen due to small, recurrent hemorrhages into the collection. These small bleeds may expand the collection enough
to make it symptomatic
acute-on-chronic SDH
often occur in patients without a clear history of head trauma as they may arise from minor head injury.
Alcoholics, the elderly, and patients on anticoagulation are at
higher risk for developing chronic SDH
Chronic Subdural Hematoma (CSDHs)
consists of a viscous fluid
with the texture and dark brown color reminiscent of motor oil.
Chronic Subdural Hematoma (CSDHs)
Isolated hematomas within the brain parenchyma are most often associated with hypertensive hemorrhage or arteriovenous malformations (AVMs)
Intraparenchymal Hemorrhage
Intraparenchymal Hemorrhage - Indications for craniotomy include:
-any clot volume >50 cm3
-clot volume >20 cm3 with referable neurologic deterioration
(GCS 6–8)
-associated midline shift >5 mm or basal cistern
compression
defect in the skull that allows air to enter the intracranial cavity. This may occur following may represent an
iatrogenic defect created following cranial surgery or following head trauma
Pneumocephalus
occurs when the intracranial
air pocket is under tension which can result in life threatening
herniation if left untreated
tension pneumocephalus
Two radiographic features have been associated with a tension pneumocephalus
1) “Mount Fuji” sign
2) “air bubble” sign
where the air pocket separates the frontal lobes and widens the inter-hemispheric fissure
“Mount Fuji” sign
where there are multi-focal pockets of air throughout the subarachnoid cisterns, putatively within the subarachnoid space
“air bubble” sign
two major mechanisms by which pneumocephalus develops
1) “ball valve”
2) “inverted bottle”
involves the passage of air into the intracranial cavity during periods of positive pressure, whereby the defect in the skull acts as a one-way valve
“ball valve”
management involves avoiding positive pressure ventilation,
and laying the head of the bed flat to minimize air traveling
upwards into the cranial cavity
“ball valve”
mechanism involves air entering the intracranial space due to a negative pressure gradient created by the drainage of CSF
“inverted bottle”
management should be focused on minimizing CSF drainage through the defect
“inverted bottle”
the head of bed must be elevated so as to reduce hydrostatic pressure in the ventricular CSF fluid column, and controlled CSF diversion can be performed using an extraventricular or lumbar drain
“inverted bottle”
Peptic ulcers occurring in patients with head injury or high ICP are referred to as
Cushing’s ulcers
refers to violation of the vessel wall intima
dissection
Blood at arterial pressures can then open a plane between the intima and media, within the media, or between the media and adventitia. The newly created space within the vessel wall is referred to as
false lumen
Traumatic dissection may occur in the carotid artery
(anterior circulation)
Traumatic dissection may occur in the vertebral or basilar arteries
(posterior circulation)
result from neck extension combined with lateral bending to the opposite side, or trauma from an incorrectly placed shoulder belt tightening across the neck in a motor vehicle accident
Carotid Dissection
Symptoms of cervical carotid dissection
-contralateral neurologic deficit from brain ischemia
-headache
-ipsilateral Horner’s syndrome from disruption of the sympathetic tracts ascending from the stellate ganglion on the surface
of the carotid artery
-bruit
result from sudden rotation or flexion/extension of the neck,
chiropractic manipulation, or a direct blow to the neck.
Vertebrobasilar Dissection
Symptoms of vertebrobasilar dissection
- neck pain
- headache
- brain stem stroke
- SAH
absence of signs of brain stem function or motor response to deep central pain in the absence of pharmacologic or systemic medical conditions that could impair brain function
Brain Death
Documentation of no brain stem function requires the following:
- nonreactive pupils
- lack of corneal blink,
- oculocephalic (doll’s eyes)
- oculovestibular (cold calorics) reflexes
- loss of drive to breathe (apnea test)
TUMORS OF THE CENTRAL NERVOUS SYSTEM
1) Intracranial Tumors
2) Metastatic Tumors
3) Glial Tumors
4) Neural & Mixed Tumors
5) Neural Crest Tumors
6) Miscellaneous Tumors
7) Embryologic Tumors
8) Spinal Tumors
commonly present with focal neurologic deficit, such as contralateral limb weakness, visual field deficit, headache, or seizure
Supratentorial tumors
cause increased ICP due to hydrocephalus from compression of the fourth ventricle, leading to
headache, nausea, vomiting, or diplopia
Infratentorial tumors
result in ataxia, nystagmus, or cranial nerve palsies
Cerebellar hemisphere
or brain stem dysfunction
Initial management of a patient with a symptomatic brain tumor generally includes
dexamethasone for reduction of vasogenic edema, and phenytoin or levetiracetam if the patient has seized
most common type of intracranial tumor
Metastatic Tumors
The sources of most cerebral metastases are (in
decreasing frequency):
lung, breast, kidney, GI tract, and melanoma
Meningeal involvement may result in carcinomatous meningitis
leptomeningeal carcinomatosis
Metastatic cells usually travel to the brain hematogenously and frequently seed the gray-white junction due to characteristic blood vessel caliber change
Metastatic Tumors
Glial Tumors
1) Astrocytoma
2) Oligodendroglioma
3) Ependymoma
4) Choroid Plexus Papilloma
provide the anatomic and physiologic support for
neurons and their processes in the brain
Glial cells
most common primary CNS
neoplasm
Astrocytoma
The term _____ often is used to refer to astrocytomas specifically, excluding other glial tumors
glioma
low-grade astrocytoma or low grade glioma
Grades I and II
anaplastic astrocytoma
grade III
glioblastoma multiforme (GBM)
grade IV
Median survival is 8 years after diagnosis
low-grade tumor
Median survival is 2 to 3 years after diagnosis
anaplastic astrocytoma
Median survival is 1 year after diagnosis
GBM
Histologic features associated with higher grade astrocytoma
- hypercellularity
- nuclear atypia
- endovascular hyperplasia
- **Necrosis is present only with GBMs
