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NS6 Neurosurgery Toronto Notes 2023

Cerebral Blood Flow

CBF -

CPP / CVR

CPP= MAP-ICP

• brain receives about 15% of cardiac output (~750 mL/min)

• CBF is the vital parameter for brain function, it depends on CPP and CV’

R

• CPP is the difference between MAP and ICP (normal CPP >50 mrnHg)

• cerebral autoregulation: mechanism that maintains constant CBI despite changes in CPP, unless:

• high ICP such that CPP <40 mmHg

• MAP >150 mmHg or MAP <50 mmHg (these setpoints can be higher in hypertensives, thus

important to avoid hypotension)

increased C02 = increased CBP via vasodilation

O2 <50 mmHg = increased CBF via vasodilation

• brain injury: e.g. SAH,severe trauma

MAP Targets in Trauma

TBI: MAP >80 mmHg

SCI:MAP between 85-90 mmHg in first

7 d post injury

Autoiegulation: CBF maintained despite

change in CPP ICP Measurement i

•normal ICP 10- 15 mmHg for adult, 3-7 mmHg for child, 1.5-6 mmHg for infant; varies with patient J

position

• ICP >25 mmHg > end-organ damage possible, treatment should be initiated

•ICP >40 mmHg > life-threatening emergency, urgent pressure reduction required

ICP measurements should be considered in the context of underlying pathology when evaluating

severity

t

- *

1

-V

o <60 iron Hu H 50 in111Hu

Low BP or High ICP High BP

Cerebral perfusion pressure (MAP-ICP)

Acute Monitoring

•indications include: severe FBI (CCS <8T) t abnormal CT; or severe '

FBI and normal CT if two or

more of: age >40, BP <90 mmHg, or abnormal motor posturing

•methods:

intraventricular catheter (EVD) is the “

gold standard”

; most accurate method and allows

therapeutic drainage of CSF

• parenchymal ICP monitor

• non-invasive methods (e.g. transcranial Doppler, CT/MR1, fundoscopy, etc.) fail to measure ICP

accurately enough to be used as routine measurement techniques

Figure 6. Cerebral autoregulation

curve

'J pledliotri:Lindsay KW.BoneI.Fuller 6.

Neurology and Neurosurgery illustrated.. 2004.

With permission fromElsevier

LP can be used (or ICP monitoring,

although it is not the most accurate.

LP can precipitate tonsillar and uncal

herniation with elevated ICP This

procedure is absolutely contraindicated

in the setting of suspected acutely raised

ICP or obstructive hydrocephalus, and

relatively contraindicated with known/

suspected intracranial mass

Chronic Monitoring

•Licox monitor (intraventricular, intraparenchymal,subdural),subarachnoid bolt (Richmond screw),

and epidural monitor

Elevated ICP

Etiology

• pathologic structure

• intracranial mass (tumour, cyst)

» cerebral edema

vasogenic: BBB compromised (meningitis,hypertensive encephalopathy, tumour, late

ischemia)

cytotoxic: BBB intact (cell death in: early ischemia, brain injury, encephalitis,status

epilepticus)

interstitial: transudation of CSF into periventricular white matter in hydrocephalus

osmotic:osmotic gradient increases intracellular free H:0 (acute hyponatremia, hepatic

encephalopathy)

other space occupying lesions: depressed skull fracture, foreign body, pus/empyema

< increased intracranial blood volume

• space occupying blood: epidural and subdural hematomas, intraparenchymal and subarachnoid

hemorrhages

• venous obstruction (venous sinus thrombosis, superior vena cava syndrome, cor pulmonale,

venous sinus compression)

• impaired autoregulation (hypotension, HTN, brain injury,status epilepticus)

• vasodilation (increased p(X):/decreascd pO’

/decreased extracellular pH)

• increased intracranial CSF volume (see Hydrocephalus, Tabic 7, NS9)

non-obstructive: increased production ( rare, choroid plexus papilloma,secretory vestibular

schwannoma), decreased absorption (e.g. post-traumatic, post-SAH/lVH, post-meningitis)

obstructive: blockage in CSF pathway

• idiopathic intracranial HTN (pseudotumour cerebri;see Idiopathic Intracranial Hypertension, .VS,S')

Consider Monitoring ICP in the

Following Situations

• Patients with an abnormal head CT

(SAH. hematoma,contusion, basal

cistern compression,swelling, and

herniation), and GCS score <8 after

CPR

OR

• Patients with a norma! head CT and

GCS score of <8 AND the presence of

two or more of the following:

• >40 yr

• Unilateral or bilateral motor

posturing

• sBP <90 mmHg

• Postoperative monitoring

• Investigation of NPH

Cautioned Medication Use in Elevated

ICP

• Nitroprusside: can raise ICP in

patients with intracranial mass

lesions due to direct vasodilation

(arterial>venous)

• Nitroglycerine:can raise ICP

via vasodilation but less so

than nitroprusside because

venous>arterial

• Succinylcholine:induced

fasciculations may increase ICP

rT

L.J

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NS7 Neurosurgery Toronto Notes 2023

Clinical Features

Table 4. Clinical Features of Elevated ICP Blood-Brain Barrier (BBB)

Glucose and amino acids cross slowly

Non polar:lipids cross fast

Clinical Features Acutely Elevated ICP Chronic Progressive ICP Elevation

Both aggravated by stooping,coughing,and straining (Valsalva)

Morning H/A: vasodilation due to increased C02 with recumbency

Present in both,though greater predilection inacutely elevated ICP

Lethargy if ICP - dBP or midbrain compression

Headache

Infarction/neoplasm •

*

destroy tight

Nausea and Vomiting junctions » vasogenic edema

LOC Irritability,inaltentiveness. Normal or modestly

reduced LOC. confusion

GCS Significant decline In GCS Can be unchanged or modestly decreased

Best index to monitor progress and predict outcome ol

acute intracranial process (see Naitoltatima.«535)

Sublie changes suggesting papilledema (subtle elevations Obvious papilledema

in disc margin,mild disc hyperemia) tretinalhemorrhages

(may take 24- 48h to develop)

Cushing's Triad of Acute Raised ICP

(Full triad soon in 1/3 of cases)

• Bradycardia (late finding)

HTN

• Irregular respiratory pattern

Optic Disc Changes

Less common.Olten not affected initially:however, visual Optic atrophy/blindness due tochronic papilledema

obscurations,flickering,or blurring can occur

Visual Changes

Enlarged blind spot,if advanced *

episodic

constrictions of visual fields ("grey-outs" lasting

~20 min)

Differentiate from papillitis (usually unilateral with

decreased visual acuity)

Papilledema

• Optic disc swelling with blurred

margins (most commonly bilateral)

• Larger blind spot

less common. CN VI palsy:due to long intracranial course. Often full extraocular movement

more sensitive lo ICP changes and thus earlier sign of

acutely increasedICP

Often falsely localiiing (causative lesion remote lo nerve)

Upward gate palsy and sunset eyes (especially in children

with obstructive hydrocephalus due lo pressure on tectal

plate)

Often occur

Focal deficits present

Extraocular Movements

Herniation Syndromes

Neurologic Deficits

Present if acule-on- chronic presentation

focal deficits can be present

f . Subtalcine

2. Central

L 3. Uncal

3 4. Upward

15. Tonsillar

Investigations

• patients with suspected elevated ICP require an urgent CT/MR1 to identify etiology, assess for MLS/

herniation

• ICP monitoring where appropriate 'S

s

1

Herniation Syndromes fi

Figure 7. Herniation types

Table 5. Herniation Syndromes

Herniation Syndrome Definition Etiology Clinical Features

1.Subfalcine Cingulate gyrus herniates under lateral supratentorial lesion Usually asymplomatic

Warns of impending transtentorialherniation

Risk of anterior cerebral artery (ACA) compression

Small pupils,moderately dilated,fixed (rostral to caudal

deterioration), sequential failure of diencephalon,medulla

Decreased LOC (midbrain compression),extraocular movement

|E0M),

'

upward gaze impairment ("sunset eyes"):compression of

pretectum and superior colliculi (Parinaud's syndrome)

Risk of posterior cerebral artery (PCA) compression

Brainstem (Durcl) hemorrhage: secondary lo shearing ol basilar

arlery perforating vessels

Ol (traction on pituitary stalk and hypothalamus), end- stage sign

Ipsilatcial non reactive dilated pupil(cailiest, most reliable sign)

-> ipsilalera! EOM paralysis, plosis (CH III compression)

Decreased LOC (midbrain compression)

Risk of PCA compression

Contralateral hemiplegia t extensor lupgoing) plantar response

1ipsilateral hemiplegia ("Kernohan's notch" - a false localizing

sign resulting from pressure from the edge of the tentorium on the

contralateral cerebral peduncle)

Cerebellar infarct (superior cerebellar artery (SCA) compression)

Hydrocephalus (cerebral aqueduct ol Sylvius compression)

hh

2. Central Tentorial (Axial) Displacement of diencephalon

through tentorial notch

Supratentorial midline lesion

Diffuse cerebral swelling

tale uncal herniation

3, lateralIcntoria (Uncal) Uncus ol temporal lobe herniates

down through tentorial nolch

lalcral supratentorial lesion (often rapidlycipandmg

traumatic hematoma)

4. Upward Cerebellar vermis herniates

through tentorial incisura

Posterior lossa mass,brainstem or cerebellar infarction,

exacerbated by ventriculostomy or ventriculoperitoneal

(VP) shunt

Infratentorial lesion

following central lenlotial herniation

following IPin presence ol intracranial mass lesion

5. Tonsillar Cerebellar tonsils tierniatc

through loramen magnum

Neck stillness and head lilt (tonsillar impaction)

Decreased LOC (midbrain compression)

flaccid paralysis

Respiratory irregularities,respiratory arrest (compression ol

medullary respiratory centres)

Blood pressure instability (compression ol medullary

cardiovascular centres) +

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XS8 Neurosurgery Toronto Notes 2023

Treatment of Elevated ICP

Treatment of Elevated ICP

• treatment principle:treat primary etiology (i.e. remove masslesions, ensure adequate ventilation e.g.

in acute respiratory distresssyndrome (ARDS))

• if elevated K.

'

P persists following treatment of primary cause, consider therapy when ICP >20 mmHg

• targets: ICP <20 mmHg,CPP 60-70 mmHg, sBP >100 (ages 50-69) or >110 (age <50 or >70) mmHg

(individualize targets based on patient's clinical picture and progression)

ICP HEAD

Intubate

Calm (sedate)fComa

Place drain/lfcralysis

Hyperventilate

Elevate head

Adequate BP

Diuretic (mannitol)

Table 6. Management of Elevated ICP

Consideration Intervention Rationale

Conservative Measures

Position Elevate head of bed at 30"

Maintain neck inneutral position

Increases

1. Jugular venouspatency

2. Intracranial venous outflow with minimal effect on MAP

Decrease basal metabolic and oxygen demands in order to

minimise brain injury

Maintains CBP

Irialof Decompressive Craniectomy for Traumatic

IntracranialHypertension

NEJM 2016:375:1119-1130

Purpose loconpaie the effect oldecompressive

craniectomy onOmul outcomes to that pimedcaf

management in patients with traumabt brain myury

(181) and refractory intracranial hypertension |HIH|.

Methods Patients with TBI and refractory

intracranialHIN >25 mmHg were randomiied to

undergo decompressive craniectomy or receive

ongo:g medical care.Primary outcome wasExtended

Glasgow OutcomeScale at 6 mo.

lesntts:Patients treated with decompressive

craniectomy had lower mortality rales|26.9% vs.

48.9%) hst tighei rates oldisability 18.53,vs. 2.1%

lower sewredisabiiity, 21.9% vs.14.4% upper severe

dsabitty.154% vs. 8.0% nodeidle disability).

Conclusion: Compared lomedical care,

decompressive craniectomy inpatients with 181and

refractory intracranialHIN results m lower mortality

but higher rates of vegetative slate and severe

disability.

Fever Management Acetaminophen or mechanical cooling

Prevent Hypotension PRN: Fluid, vasopressors, dopamine,

norepinephrine

Ventilate to pCOi 35- 40 mmHg

Target pOa »60 mmHg

Normocarbia Prevents vasodilation

Adequate 02

Osmolar Diuresis

Prevents hypoxic brain injury

Mannitol 20% IV solution1-1.5 g/kg,then 0.25 g/kg Increases serum tonicity -*

osmolically drives fluid out of

q6 h to serum osmolarily of 315-320 mOsm/kg brain

Ads in 15-30 min,maintain sBP >100 mmHg

Hyperionic saline 3% comparable lo mannitol

Dexamethasone Decrease vasogenic edema over subsequent days around

brain tumour, abscess,blood

No proven value In head Injury or siroke

Corticosteroids

Aggressive Measures

Sedation Usually propolol

Others:barbiturates/codeine, or fenlanyl/MgS04

Light - barbiturateslcodeine

Heavy -fentanyl/MgS04

Vecuronium

Reduces sympathetic tone

Reduces HIN induced by muscle contraction

Reduces sympathetic tone

Reduces HTNinduced by musdecontraction

Reduce CBF and metabolism

Decreases mortality, but no elfect onneurologic outcome

No role lor the use ol hypothermia in head injury

Decreases CBF and thus ICP. but use lor Uriel periods only

Paralysis

Barbiturate-Induced Coma Phenobarbital 10mg/kg over 30 min. then 1mg/

(refractory ICP) kg qlh continuous inlusion

Hyperventilate Target pCOz 30-35 mmHg

Avoid within 24 h following trauma

Insert EVD (it acute)or shunt

Drain 3-5mLCSF

Decompressive craniectomy

Drain CSF Reduces intracranial volume

Decompression Allows brain to swell while reducing risk of herniation

Idiopathic Intracranial Hypertension

(Pseudotumour Cerebri)

Definition

• raised ICP with papilledema, but without: mass, hydrocephalus, infection, or hypertensive

encephalopathy (diagnosis of exclusion)

• diagnosed by modified Dandy’s criteria

Etiology

• unknown (majority), but associated with:

vascular: dural venous sinus thrombosis

habitus/diet: obesity, hypervitaminosis A

endocrine: reproductive age, menstrual irregularities,Addison's/Cushing's disease

• hematologic: iron deficiency anemia, polycythemia vera

drugs:steroid withdrawal, tetracycline, amiodarone, lithium, nalidixic acid, oral contraceptive,

growth hormone, retinoids

• risk factors overlap with those of venous sinus thrombosis;similar to those for gallstones (“fat, female,

fertile,forties")

Modified Dandy's Criteria

1. Symptoms olraised ICP

2.No localizing signs except CN VI palsy

3.Patient awake and alert

4.Normal neuroimaging without

evidence of thrombosis

5.LP opening pressure >25 cm ECO,

normal CSF

6.No better explanation for raised ICP

r T

L J

Epidemiology

• incidence: general population -I -2 in 100000 per yr;women of childhearing age with obesity 19-21 in

100000 per yr

+

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NS9 Neurosurgery Toronio Notes 2023

Clinical Features

•symptoms: H/A in >90%, nausea, transient visual obscurations, pulsatile tinnitus,diplopia can occur

with CN VI palsy, neck/back pain

•signs:CN VI palsy can occur (otherwise no neurologic deficits), visual acuity and field deficits,

papilledema, optic atrophy

•morbidity: risk of blindness and severe visual impairment (6-24% risk) are the major morbidity of

idiopathic intracranial hypertension (11H ), but are not reliably correlated to duration,symptoms, or

clinical course

•clinical course: usually self-limited, recurrence in 10%, chronic in some

Investigations

•MRI brain (with and without contrast): slit-like ventricles and distended perioptic subarachnoid

space, but otherwise normal

rule out: venous sinus thrombosis, mass, infection, hydrocephalus

•LP findings

opening pressure >25 cmH’

O

normal CSP analysis

• ophthalmologic: fields, acuity, papilledema

Effect of Acetazolamide on Visual Function

in Patients with Idiopathic Intracranial

Hypertension and Mild Visual toss(IIHTT)

JAMA 2014:311(16|:1641-1651

Purpose :to determine whether acetarolamide and

a low-sodi un weight reduction diet is beneficial in

impronrg ms- on compared to diet alone m patients

with IIH and mild visual loss.

Methods patients were landomited to Mirer a

tow-sodium wreigM reduction diet plus the maiireally

tolerated dosage of acetaiolamideor placeSo for

Smo.

Desilts:Acelaiolamide wassuperior to placebo with

regards toperimetric mean deviation improvement

(P^O.05).papilledema grade improvement tP« 0.001).

insios-related quality of life (H.003),and weight

reduction (M1.001).

Conclusion: Acetazolamide w tit low-sodium weightreduction diet resulted In Improvement in visual field

function in patients with IIH and mildvisual loss.

Treatment

• lifestyle change: encourage weight loss, fluid/salt restriction

• pharmacotherapy: acetazolamide (decreases (

’SI production ), thiazide diuretic, or furosemidet

discontinue offending medications

• surgery: if above fail,serial LPs (temporizing), optic nerve sheath fenestration (if progressive

impairment of visual acuity),shunt placement (ventriculo-peritoneal, lumbo-peritoneal)

• long term: 2 yr follow-up, repeat imaging to rule out occult tumour,ophthalmology follow-up

Hydrocephalus

• for hydrocephalus in children,see Paediatric Neurosurgery. NS42

Definition

•accumulation of excess CS1

;

in the brain, functionally divided into obstructive and communicating

• flow of CSF: produced by choroid plexus, lateral ventricles > foramen of Monro > 3rd ventricle

> cerebral aqueduct of Sylvius > 4th ventricle > foramen of Luschka (lateral) and Magendie

(medial) > subarachnoid space where CSF is reabsorbed by arachnoid villi/granulations into

dural venous sinuses

Classification

CSF production - CSF reabsorption *

-•500 mL/d in normal adults

Normal CSF volume ~150 mL (50%

spinal. 50% intracranial » 25 mL

intraventricular, 50 ml subarachnoid)

Table 7. Classification of Hydrocephalus

Disorder Definition Etiology Findings on CT/MRI

CSF circulation blocked Acquired

within ventricular system Aqucductal stenosis: adhesions alter

proximal to the arachnoid inlection, hemorrhage:gliosis,tumour|e.g.

granulations medulloblastoma)

Intraventricular lesions: tumours,e.g. 3rd

ventricle colloid cyst, hematoma

Mass causing tentorial herniation causing

aqueduct/4th ventricle compression

Others: neurosarcoidosis,abscess/granulomas.

arachnoid cysts

Obstructive ( NonCommunlcatlng)

Hydrocephalus

Ventricular enlargement proximal

to block (enlarged temporal

horns, ballooning frontal and/or

occipital horns, enlarged 3rd14th

ventricles)

Periventricular hypodensity/

lucency (transependymal

migration of CSF forced info

extracellular space)

Sulcal effacemenl, reduced

visibility of Sylvian and

Congenital interhemispherlc fissures

Primary aqueductal stenosis. Dandy -Walker

malformation. Arnold -Chian malformation,

myelomeningocele,enccphalocele (see /

’ot

-tfra/nc

Hmosurgeiy.#542)

Post infectious (#1 cause)*meningitis, abscess. All ventricles dilated

cysticercosis

Post- hemorrhagic (

*2 cause) -» SAH. IVH. traumatic

Leptomeningeal carcinomatosis- metastatic

meningitis

Choroid plexus papilloma

Idiopathic » NPH

Idiopathic (50%)

Others:SAH. meningitis,trauma, radiationinduced

MosIcommonlyCSF

absorption blocked at

extraventricular site *

arachnoid granulations,

rarely CSF absorption is

overwhelmed by increased

production

Persistent ventricular

dilation In the con text ol

normal CSF picssure

Ventricular enlargement Normal aging

resulting Irom atrophy ol Degenerative dementias:Alzheimer's,

surrounding brain tissue frontotemporal.Crculzleldt Jakob disease|sce

Neuioloqy. N 2?|

Non -Obstructive

(Communicating)

Hydrocephalus

1. Lateral ventricles

2.Choroid plexus

3.Third ventricle

4.Cerebral aqueduct (of Sylviusl

5.Fourth ventricle

-

6. Foramina of Luschka and Magendie 2

7.Arachnoid granulations

8.Subarachnoid space

9.Confluence of sinusesItorcula)

r t

5

L J

Normal Pressure

Hydrocephalus (NPH)

Enlarged ventricles without

increased prominence of cerebral

sulci

Figure 8. The flow of CSF

Enlarged ventricles and sulci

Cerebral atrophy

Hydrocephalusfx

Voeuo +

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NS10 Neurosurgery Toronto Notes 2021

Etiology

• impaired CSF dynamics

• obstruction of CSF How

• decreased CSF absorption

increased CSF production ( rarely in choroid plexus papilloma 0.4- 1% of intracranial tumours)

• congenital and acquired causes

Epidemiology

• estimated prevalence 1-1.5%; incidence of congenital hydrocephalus -1-2 in 1000 live births

Clinical Features

• acute hydrocephalus:signs and symptoms of acutely elevated ICP (see Table 4\, S7 )

• chronic/gradual onset hydrocephalus:(wk to mo;i.e. NPH) presents with a classic triad (Hakim’

s

triad)

• Ataxia (magnetic gait) i apraxia (pressure of ventricle on lower extremity motor fibres > gait

disturbance)

• Incontinence (pressure on cortical bowel/bladder centre)

• Dementia (subcortical)

Classic (Hakim's) Triad of NPH

Progression

“W*t. wacky,wobbly": Incontinence,

dementia, ataxia

Important Features to Note on CT and

MRI (± contrast enhancement)

• Lesions (iedema,necrosis,

hemorrhage)

• MLS and herniations

• Effacement of ventricles and sulci

(often ipsilateral). basal cisterns

• Single or multiple (multiple implies

metastasis)

Investigations

• imaging

• CT/MR1 findings (see Table 7, NS9)

• ultrasound (through anterior fontanelle in infants): ventriculomegaly. size and location of lesions

(e.g. lVH )

mantle radionuclide cisternography can test CSF flow and absorption rate (unreliable)

• ICP monitoring (e.g. LP, EVD) may be used to investigate NPH and test response to shunting (lumbar

tap test)

Treatment

• EVD (acute hydrocephalus, intraventricular hemorrhage)

• intermittent LPs for transient communicating hydrocephalus (SAH, 1VH in premature infants)

• eliminating obstruction (i.e.excision of mass, posterior fossa decompression for Chiari malformation)

• endoscopic

endoscopic third ventriculostomy (ETV) ± choroid plexus cauterization (for obstructive

hydrocephalus)

• endoscopic placement of aqueductal stent

Complications of Specific

Hydrocephalus Treatments

1. VP Shunt:intra abdominal cysts,

adhesions,ascites

2. VA Shunt:greater infection risk,

septicemia,emboli

3. Ventriculopleural Shunt:pleural

effusion, hydrothorax, respiratory

distress

4. LP Shunt radiculopathy. CSF leaks,

adhesions,arachnoiditis

5. ETV:56% success rate, hypothalamic

injury, iatrogenic basilar aneurysm

• shunt

• VP: most common shunt

ventriculopleural

ventriculoatrial (VA)

lumboperitoneal:for communicating hydrocephalus and pseudotumour cerebri

Shunt Complications

Table 8. Shunt Complications

Complication Etiology Clinical Features Investigations

Obstruction by choroid plexus

Buildup of proteinaceous accretions, blood, cells ICP

(inflammatory or tumour)

Infection

Disconnection or damage

5. epidermidis

S. aureus

P. owes

Gram- negative bacilli

Acute hydrocephalussigns and symptoms of increased "Shuntseries" (plain x-rays of entire shunt that only

rule-out disconnection, break, tip migration)

Obstruction

(most common)

Proximal Catheter

Valve

Distal Catheter

Infection

(3-6%)

C!

Radionuclide "shunlogram"

fever, N/V.anorexia, irritability

Meningitis

Peritonitis

Signs and symptoms of shunt obstruction

Shunt nephritis(VA shunt)

Slit ventricle syndrome, collapse of ventricles Chronic or recurring H /A often iclieved when lying

leading lo occlusion olshunt ports by ependymal down

lining

CBC

Blood culture

Tap shunt for CAS (LP usually NOT recommended)

Overshunting

(10% over 6.5 yr)

C1/MRI

Slil-like ventricles on imaging

SDH Asymptomatic CT

Collapsing brain tears bridging veins(especially H/A, vomiting,somnolence

common in NPH patients)

Secondary craniosynostosis(children):

apposition and overlapping ol the cranial

sutures in an infant following decompression ol

hydrocephalus

Ventricular shunts only

Abnoimalhead shape Clinical

CT

Seizures

(5.5% risk in1st yr,1.1% after 3rd yr)

Inguinal hemia

(13-15% incidence when shunt

inserted in childhood)

EEC

Increased intraperitoneal pressure/fluid results Inguinal swelling, discomfort +

in hernia becomingapparcnt

U /S

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NS11 Neurosurgery Toronto Notes 2023

Spontaneous Intracranial Hypotension

Definition

• low CSI;

pressure t postural headache secondary to CSI:

leak

• symptoms not attributable to another disorder, no recent history of dural puncture

Etiology

• CSI;

leakage from the thecalsac within or along the spinal canal

Epidemiology

• incidence: ~2-5 in 100000 per yr,but likely underdiagnosed; M:l-

'

=1:2

can occur at any age, but most frequently in 4th or 5th decade

Clinical Features

• symptoms: orthostatic H/A in 75-80%,tinnitus or auditory disturbance (“underwater feeling") in

50%,dizziness in 50%, nausea, vomiting, photophobia, meningismus

• signs:CN 111,CN IV, CN VI palsy in <10%

• morbidity: misdiagnosis and underdiagnosis are common, leading to delays in treatment and

inappropriate treatment for mimickers of intracranial hypotension

• clinical course: usually self-limited, recurrence in 10%, chronic in some

Investigations

• MKI brain with contrast:sagging of the brain (e.g. low cerebellar tonsils), pachymeningeal

enhancement,subdural hematoma or hygroma, pituitary hyperemia

• MKI spine with contrast:extrathecal fluid collections/extrathecal contrast accumulation and/or

meningeal diverticula

• CT myelogram with contrast:preferred method to diagnose and localize CSF leak

digital subtraction myelogram (DSM): combinesfluoroscopy and ability to subtract background

imagesto visualize small CSF leaks by contrast extravasation

• LP:opening pressure <6 cmHiO; xanthochromia, elevated protein, lymphocytic pleocytosis

Treatment

• conservative management: bed rest, hydration, caffeine, possibly theophylline

• epidural blood patch: mainstay treatment; autologous blood (10-20 niL) injected into epidural space

• surgery:indicated if epidural blood patches are ineffective and site of leak has been localized

CNS Tumours E

Ventricular: colloid cyst,choroid plexus

papilloma, ependymoma,

germinoma, teratoma,

meningioma

DDx for Ring Enhancing lesion on CT

with Contrast , Supratentorial extra-axial:

K

^

meningioma.cysts

/ MAGICAL DR

Metastases*

Abscess*

Glioblastoma (high-grade glioma)*

Infarct

Contusion

AIDS (toxoplasmosis)

lymphoma

Dcmyclinatlon

Resolving hematoma. Radiation Necrosis

(*3 most common diagnoses)

I

\

\ Supratentorial

intra-axial:

astrocytoma,

[glioblastoma,

oligodendroglioma,

ganglioma,

!lymphoma,

metastases

. I -s.

'N

/

lt

chordoma

Skull

jugulare

base

, osteoma

,

:

glontus

carcinoma

—

,

^

V.\ -Posterior fossa intra-axial:

schwannoma,meningioma,

cysts, metastases.

medulloblastoma *

Ring Enhancing Lesions in Patients

with HIV

DDx:toxoplasmosis or CNS lymphoma

Treatment: Empiric treatment with

pyrimethamine and sulfadiazine:brain

biopsy if no resolution with antimicrobial

therapy

Primary CNS lymphoma reported in

6-20% of HIV infected patients\

Sellar or suprasellar: \

pituitary adenoma, |

craniopharyngioma,

optic nerve glioma, cyst

\ Posterior fossa extra-axial:

schwannoma, meningioma,

cyst, metastases oT

Figure 9. Tumours of the CNS n

iJ

Classification

• benign vs.malignant, primary vs.metastatic (e.g. primary in breast, lung), intra-axial (parenchymal)

vs. extra-axial,supratentorial vs. infratentorial, adult vs. paediatric

• benign: non-invasive, but can be devastating due to mass effect in fixed volume of skull (e.g. most

meningiomas)

• malignant: implies rapid growth, invasiveness, possibly drop-metastases to spinal cord from a

primary CNS tumour (rare)

+

Primary Brain Tumours

Rarely undergo metastasis

Adults - mostly supratentorial

Children - mostly infratentorial

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XS12 Neurosurgery Toronto Notes 2023

• Based on the 2021 WHO Classification of Tumours of the CNS guideline which integrates molecular

diagnostics with other diagnostic approaches (i.e. immunohistochemistry,histology)

Table 9. WHO 2021Classification of Tumours of the CNS

Gliomas, Glioneuronal Tumours, Neuronal Tumours

Adult-lype diffuse qliomas Astrocytoma.IOH -mulant

Oligodendroglioma, IDH mutant,and 1p/19q-codelcled

Glioblastoma, IDH-wildlypc

Oiffuse astrocytoma. MYB- or AMlf-altered

Angiocentric glioma

Polymorphous low-grade neuroepithelial tumour of the young

Diffuse low-grade glioma.MAPK pathway-altered

Diffuse midlrne glioma,H3K27-allcred

Diffuse hemispheric glioma.H3G34-mutant

Diffuse paediatric-type high- grade glioma. H3-wildlypc and IDH wildtype

Infant-type hemispheric glioma

Pilocytic astrocytoma

High-grade astrocytoma with piloid features

Pleomorphic lanthoastrocytoma

Subependymal giant cell astrocytoma

Chordoid glioma

Astroblastoma,MUI- altered

Gangliogtioma

Desmoplastic infantile ganglioglioma/desmoplastic infantile astrocytoma

Dysembryoplastic neuroepithelial tumour

Diffuse glioneuronal tumourwith oligodendroglioma-like features and nuclear clusters

Papillary glioneuronal tumour

Rosette- forming glioneuronal tumour

Myxoid glioneuronal tumour

Diffuse leptomeningeal glioneuronal tumour

Gangliocytoma

Multinodular and vacuolatingneuronal tumour

Dysplastic cerebellar gangliocytoma (Lhermitte-Duclos disease)

Central neurocytoma

Extraventricular neurocytoma

Cerebellar liponcurocytoma

Supratentorial ependymoma (includingIflAfusion- positive or YAPI fusion-positive)

Posterior fossa ependymoma (including group PfA andPf8)

Spinal ependymoma (including AWAf-amplified)

Myxopapillary ependymoma

Subependymoma

Paediatric-type diffuse low- grade gliomas

Paediatric- type diffuse high- grade gliomas

Circumscribed astrocytic gliomas

Glioneuronal andneuronal tumours

Ependymal tumours

Choroid Ploxuslumours

Choroid plexus papilloma

Atypical choroid plexuspapilloma

Choroid plexus carcinoma

Embryonal Tumours

Medulloblastoma Medulloblastomas,molecularly defined:WNI-activated.SHH-activaled and IPS3-

wildtype.SHH -adivaled and fPSTmutant, non-WNI/non- SHH

Medulloblastomas, histologically defined

Atypical teratoid/rhabdoid tumour

Cribriform neuroepithelial tumour

Embryonal tumour with multilayered rosettes

CHS neuroblastoma,POWi

-activated

CNS tumour withBCOB internal tandem duplication

CHS embryonal tumour

Other CHS embryonal tumours

Pineal Tumours

Pineocytoma

Pineal parenchymal tumourof intermediate

differentiation

Pineoblastoma

Papillary tumour of the pinealregion

Desmoplastic myxoid tumour of the pinealregion.

JM/MOf-mutant

Cranial and Paraspinal Nerve Tumours

Schwannoma

Neurofibroma

Perineurioma

Hybrid nerve sheath tumour

Malignant melanotic nerve sheath tumour

Malignant peripheral nerve sheath tumour

Paraganglioma

r1I

1 I J

Meningiomas +

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NS13 Neurosurgery Toronto Notes 2023

Table 9. WHO 2021Classification of Tumours of the CNS

Mesenchymal.Non-Meningothclial Tumours

Soil tissue tumours Fibroblastic and myofibroblastic tumours:solitary fibrous tumour

Vascular tumours:haemangiomas and vascular malformatrons. hemangioblastomas

Skeletal muscle tumours:rhabdomyosarcoma

Uncertain differentiation:intracranial mesenchymal tumour.fCJ-CUB mutation positive,

C/f-rearranged sarcoma,primary intracranial sarcoma.0/f£W-mutant.Ewing sarcoma

Chondrogenic tumours:mesenchymal chondrosarcoma,chondrosarcoma

Notochordal tumours:chordoma (including poorly differentiatedchordoma)

Chondro-osseous tumours

Metanocytic Tumours

Diffuse meningeal melanocylic neoplasms Meningeal melanocylosis

Meningeal melanomatosis

Meningeal melanocyloma

Meningeal melanoma

Circumscribed meningeal melanocylic neoplasms

Hemalolymphoid Tumours

lymphomas CNS lymphomas:primary diffuse large 8- cell lymphoma olthe CKS. mmunodefluencyassociated CNS lymphoma,lymphomatoid granulomatosis,intravascular large B cell

lymphoma

Miscellaneous rare lymphomas in the CNS: MALT lymphoma of the dura,other low-grade

B-cell lymphomas of the CNS,anaplastic large cell lymphoma [ALK*

/ALK-).T-cell and

NK/T-cell lymphomas

Erdheim-Chesler disease

Rosai-Dorfman disease

Juvenile xanthogranuloma

Langerhans cell histiocytosis

Histiocytic sarcoma

Histiocytic tumours

Germ Cell Tumours

Teralotna:mature,immature,somatic - type malignancy

Germinoma

Embryonal carcinoma

Volk sac tumour

Choriocarcinoma

Mixed germ cell tumour

Tumours of theSellar Region

Adamantinomatous craniopharyngioma

Papillary craniopharyngioma

Pituicy toma.granular cell tumour of the sellar region,

and spindle cell oncocytoma

Pituitary adenoma/PitNET

Pituitary blastoma

Metastascs to the CNS

Mctasfases to the brain and spinal cord parenchyma

Metastases to the meninges

Familial Syndromes Associated with CNS Tumours

• ataxia telangiectasia

• Cowden syndrome

• familial adenomatous polyposis

• hereditary non-polvposis-related colorectal cancer

• Li-l-

'