Clin Med Neurosurgery Flashcards
Where is cerebrospinal fluid (CSF) produced?
choroid plexus tissue in ventricles - mainly in lateral ventricles
CSF circulates…
unilaterally through ventricles, then multidirectionally through subarachnoid space
CSF is reabsorbed…
through dural venous sinuses through arachnoid granulations
Define hydrocephalus
Excessive accumulation of CSF in brain resulting in increased intracranial pressure (ICP)
Define ventriculomegaly
Dilation of the ventricles in the brain
Ventriculomegaly & hydrocephalus
ventriculomegaly does not equal HCP
Hydrocephalus symptoms
- Headache
- Recurrent emesis (not related to diarrhea or any other GI symptom)
- Lethargy
- Irritability
- Papilledema
- Sundowning (commonly seen in children, they physically can’t look up)
Hydrocephalus in infants
- macrocephaly (FOC crossing percentiles)
- full/firm fontanelle
- splayed sutures
- prominent scalp veins
Advanced hydrocephalus
Cushing’s triad:
- increased blood pressure
- bradycardia
- irregular breathing
Communicating hydrocephalus
- Entire ventricular system dilated
- Problem with absorption of CSF
- Post-hemorrhage
- Post meningitis - Or overproduction
- Choroid plexus tumors
- Choroid plexus hyperplasia
Noncommunicating/obstructive
hydrocephalus
- Dilation of ventricular system upstream from block
- Aqueductal Stenosis
- Tumors
Ex-vacuo in relation to hydrocephalus
- could be seen in a kid who has had a bad infection or stroke, so the brain is atrophied
- it looks like hydrocephalus on CT, but the physical exam doesn’t match it
Hydrocephalus dx
- CT is the easiest, but US is good for children with fontanelle
- can also use MRI
- consult ophthalmology to evaluate for papilledema
- intracranial pressure monitor (normal ICP < 20 mm Hg)
What are shunts?
used to create an alternate outflow for CSF
Types of shunts
- Ventriculo-peritoneal (VPS)
- Ventriculo-atrial (VAS)
- Ventriculo-pleural
- Subgaleal
Components of shunts
- Ventricular catheter (proximal)
- Valve/reservoir
- Distal catheter
Subgaleal shunt
- temporary (lasts about 4 weeks)
- ends in a subgaleal pocket created during surgery
- for pts with low body weight <1500 grams
What newborn condition are subgaleal shunts often used for?
Intraventricular Hemorrhage (IVH) of Newborn: high RBCs or protein in CSF -this basically turns to a sludge and clogs the valves of other shunts
Shunt malfunctions manifest as…
hydrocephalus symptoms, because it’s as if you don’t have a shunt at all.
Shunt malfunctions
- stats
- reasons why
- 50% of shunts fail in first 2 years of life, then 10% per year
- no rhyme or reason why they fail but,
- MC reason is proximal - tissue clogs holes, malpositioned catheter
- other reasons: valve clogs
- distal reasons: fractured tubing, infection
Dx of shunt malfunction
CT, shunt series, and shunt tap
Shunt infections
- Usually occur at time of surgery with skin flora
- Occur within first 6 months following placement
- Typically a distal malfunction
- Tx: Externalize shunt, IV antibiotics, then replace entire shunt system
External ventricular drains (EVD)
- A short term solution
- Direct drain from ventricle with usually frontal placed catheter to drainage system
- Level of chamber acts as valve (low drains more, high drains less)
Endoscopic third ventriculostomy (ETV)
- Creates an alternative pathway within the brain
- Works for cases of obstruction at level of aqueduct
Who does ETV not work well on??
Does not work well on infants or communicating hydrocephalus
Choroid plexectomy
- Coagulate or remove choroid plexus
- Decreases CSF production enough to control head growth
- Works for patient with little or no cerebral cortex
Intraventricular hemorrhages (IVH)
- Arises from germinal matrix
- Graded I-IV
- May cause communicating hydrocephalus
- Dx by head US
What population is at risk for IVH?
Infants born more than 10 weeks premature are at greatest risk
What is often confused as hydrochephalus?
Benign extra-axial fluid of infancy
Benign extra-axial fluid of infancy characteristics
- Normal variant
- Enlarged subarachnoid spaces over frontal poles with normal ventricular size
- Macrocephalic with flat fontanelle
- Asymptomatic
- May be familial macrocephaly
- Usually resolves spontaneously by 2 years old
Define spina bifida
Neural tube fails to develop or close properly causing defects in spinal cord and vertebrae
- 1-2/1500 live births
- genetic and environmental factors
2 types of spina bifida
Open (myelomeningocele or meningocele) v. Closed (lipomyelomeningocele) neural tube defect
What 3 factors are most strongly correlated to spina bifida?
Carbamazepine, Valproic acid, and low folate most strongly related
Spina bifida level of defect
*determines physical findings
L2 - Hip flexors L3 - Knee extensors L4 - Knee flexors, ankle dorsiflexors L5 - Long toe extensors S1 - Ankle plantar flexors S2-4 - Bowel/bladder sphincter
The higher the defect, the less the patient is able to do.
Tx of spinda bifida
- Keep patient flat/prone with sterile saline soaked gauze and IV antibiotics for open defects
- Close open defects within first 48-72 hours of life
- Closed defects can be repaired around 6 months of life
- Layered repair closure – bring the layers of the spinal cord as close together as possible, then layer muscle, then skin
- In utero fetal closure
Spina bifida late problems
- Neurologic - 80-90% of patients have HCP and require shunting (Higher lesion = higher risk of hydrocephalus)
- Chiari malformation
- syrinx
- tethered cord
- Often need orthopedics for scoliosis, clubfoot, etc.
- 100% have neurogenic bladder
- latex allergy
Tethered Cord
occult spina bifida
- Tissue attachments limit the movement of spinal cord within the spinal column
- Causes abnormal stretching of spinal cord
- Low conus or fatty filum terminals
Signs of tethered cord
Cutaneous lesions:
- Tuft of hair
- Hemangioma or nevus
- Dermal sinus
- Dimple
- Asymmetric gluteal cleft
- Subcutaneous lipoma
- Tail
Symptoms of tethered cord
- changes in lower extremity strength/sensation
- gait abnormality – walk on outsides of feet
- back/leg pain
- bowel/bladder issues (incontinence/retention)
- may cause scoliosis
Dx of tethered cord
***MRI is gold standard
Lumbar spinal ultrasound in newborn - 6 months old
Lumbar MRI if ultrasound abnormal or > 6mo
Surgery for tethered cord
- lumbar laminectomy with microscopic sectioning of filum
- early surgery (even if asymptomatic) is recommended, because over time they’ll eventually get symptoms
- incontinence is often the first symptom and regain continence in only 50%
Encephalocele
- neural tube defect resulting in extension of intracranial structures outside normal confines of skull
- 1 in 12,000 births
- most often occipital or frontal
Chiari malformation
- cerebellar tonsils extend through the foramen magnum > 5mm, resulting in compression of cerebellum and brainstem and possible alteration of CSF flow (associated hydrocephalus)
- typically asymptomatic and an incidental finding
Types of chari malformation
Classified as 3 types: I, II (Arnold-Chiari) & III
Which type of chiari malformation is associated with spina bifida?
Type II (Arnold-Chiari)
*typically asymptomatic
Dx of chiari malformation
C-spine CT or MRI
Symptoms of chiari malformation
- Occipital headache with exertion, coughing, sneezing or straining
- Balance problems, dizziness
- Muscle weakness or numbness
- Trouble speaking or swallowing
- Problems with hand coordination, fine motor skills
*often asymptomatic, symptoms may not develop until adolescence or adulthood
Chiari malformation may be associated with…
syringomyelia
-may also have associated hydrocephalus
Define syrinx
- tubular cyst within central canal of spinal cord which results in pain, weakness, and stiffness in the back, shoulders, arms, or legs
- if severe, may have loss of pain or temperature sensation
When to operate for chiari malformation
- severe headaches or presence of a syrinx
- surgery involves removing portion of posterior fossa skull and lamina of C1/C2 aka “Posterior fossa decompression (PFD)”
GFS scale for head trauma
- Minor head injury 15-13
- Moderate head injury 13-9
- Severe head injury <= 8
- Even if you are dead you have a score of at least 3
In a patient with head trauma you assess…
- assess motor strength and sensation in all extremities
- assess reflexes
- cranial nerve exam (check EOM, make them stick out their tongue, make them smile)
Skull fracture
- Very common
- May have associated intracranial injuries
- In infants/children: make sure mechanism of injury fits to rule out NAT (non-accidental trauma aka child abuse)
Skull fracture symptoms
-Headache
-emesis
-lethargy
+/- LOC
-overlying scalp edema
-bleeding from nostrils/ears
Dx of skull fracture
noncontrast CT
Skull fracture types
- simple, linear, non-displaced
- depressed
Simple skull fracture
- Nonsurgical
- 24 hours observation
- if through sinus/mastoid, may have pneumocephalus or CSF leak
Depressed skull fracture
- more significant trauma
- clinical judgement about surgery
Growing skull fracture
- involves a dural tear
- usually involves severe underlying brain injury
- delayed repair necessary
Epidural hematoma (EDH)
- Accumulation of blood between skull and dura
- Brief LOC followed by lucid interval, then obtundation
- Deterioration typically over a few hours
EDH is usually a disruption of what artery?
Middle meningeal A
EDH on CT
Crescent shape
-represents space-occupying lesion to brain and can lead to herniation
Tx of EDG
Evacuate blood with craniotomy
Subdural hematoma (SDH)
- Blood between dura and arachnoid
- Can be acute, chronic or acute on chronic
Vessels involved in SDH
Tearing or bridging veins of brain
SDH on CT
follows contours of brain
Tx of SDH
depends on size and growth
Subarachnoid hemorrhage (SAH)
- Bleeding between arachnoid membrane and pia matter
- Often minor head trauma or due to ruptured cerebral aneurysm
Symptoms of SAH
“thunderclap” headache, neck stiffness
SAH on CT
within arachnoid folds
Tx of SAH
Angiogram/embolization if indicated
Why is SAH called chemical meningitis?
the blood inside their head is really irritating and it hurts like meningitis
Intraparenchymal Hemorrhage (IPH)
- Usually moderate to severe trauma
- Essentially bruise of brain near bony prominence
IPH on CT
rounded white spot
Diffuse axonal injury (DAI)
- sloshing of brain in skull shears axons
- cellular level damage
- may not even have increased ICP despite poor neurological exam
DAI on CT
little to no CT findings
Non-accidental trauma
- Story is often not consistent
- Common story: baby found not breathing or scalp swollen with no known cause of injury
- Any level of injury: simple fracture to DAI
What is the “incredibly shrinking brain”?
Significant anoxic injury and stroke – then the brain dies off
Cranial sutures
- Allow passage through birth canal, growth of skull and absorb mechanical forces during childhood
- Metopic typically closes between 3-9 months
- Coronal, sagittal and lambdoid sutures close between 22-39 months
Define Plagiocephaly
Benign positional molding
“Parallelogram skull”
Characteristics of plagiocephaly
- Ear forward on side of flattening with frontal bossing
- No pressure on brain
- No imaging needed
- Improves with repositioning and time
- No neurosurgical intervention/helmets indicated
Craniosynostosis
- Fusion of suture present at birth
- Worsens with time
- No movement across suture and ridging on palpation
- requires surgical correction
Dx of craniosynostosis
3D head CT is definitive study
Metopic synostosis
- Trigonocephaly
- Narrow bitemporal width
- Lateral orbital rims retracted
- May only result in metopic ridging on the forehead
Coronal synostosis
- Asymmetry of forehead - flat forehead on ipsilateral side
- Harlequin eye
- Trapezoid shape
- Ear forward on flat side
Sagittal synostosis
- Most common
- Scaphocephaly with parietal narrowing
- Frontal and occipital bossing
Lambdoid synostosis
- Unilateral occipital flattening
- Ear posterior
- Forehead not protruded
- Trapezoid
- Often confused with plagiocephaly
Which synostosis is the most common?
Sagittal
Lambdoid synostosis is often confused for…
plagiocephaly
Craniosynostis surgery
- Cranial vault remodeling (CVR)
- Synostectomy: removal of affected suture
- May involve both neurosurgery and plastic surgery
Plagio vs. cranio
review slide 65
Small anterior fontanelle
- Normal variant
- Fontanelle closes between 1-24 months
- Check growth curve
- Development
- Shape of head
Most pediatric brain tumors are…
primary tumors
Location of brain tumors
60% located in posterior fossa, 40% in cerebral hemispheres
Types of brain tumors
- medulloblastoma
- juvenile pilocytic astrocytoma (JPA)
- ependymoma, diffuse internsic pontine glioma (DIPG)
- craniopharyngioma
Symptoms of brain tumor
- headache (worse in morning or awakens pt at night)
- vomiting
- ataxia
- vision changes
- memory changes
- seizures
Dx of brain tumor
MRI with and without contrast
-also obtain MRI of C/T/L spine with and without contrast to look for metastasis
Brain tumor surgery
biopsy, tumor debulking
Tx of brain tumor
Further treatment including chemo, proton therapy or radiation therapy as indicated by heme/onc
Arachnoid cyst
- Congenital
- Typically asymptomatic and incidental finding
- Most common in middle cranial fossa
- Surgery if causing localized headaches or pressure on surrounding brain
