Anesthesia for Hydrocephalus and Neural Defect Surgery

ARBA MINCH UNIVERSITY
DEPARTMENT OF ANAESTHESIA
erioperative Anesthesia management for
Hydrocephalus and Neural defect congenital
anomalies surgical treatment
By: Kanbiro Gedeno(BSC, MSC in ACA)
kanbgedeno45@gmail.com

Outline:
 Objectives
 Introduction
 Pathophysiology
 Perioperative management of:
 Shunt/ventricular drain placement;
 Endoscopic third ventiriculostomy (ETV)
 Meningiomyelocele repair
 References
3/9/2023 kanbgedeno45@gmail.com 2

Objectives:
 At the end of this presentation, you will be able to:
 Explain about CSF production and hydrodynamics
pathophysiology
 Discuss the intracranial compliance management
 Discuss associated congenital anomalies
 Provide perioperative management for challenges
related with hydrocephalus and neural tube defects

Introduction: Hydrocephalus
 Hydrocephalus: the excess accumulation of CSF in the ventricular
system, caused by obstruction to CSF flow or excess CSF production.
 The incidence estimated at 3-5 /1000 live births.
 An estimated 750,000 people have hydrocephalus, approximately 160
000 VP shunts are inserted worldwide each year.
 Without surgery only 20% reached adulthood and 50% of the
survivors were brain damaged.
 The development of silicone shunt systems have dramatically
improved the outcome.
(Kahle KT et al. 2016)

Background pathophysiology:
Cerebrospinal fluid (CSF): is continuously produced
by:
 Choroid plexus: 60-75% of CSF by lateral ventricles,
third and fourth ventricles
 Extrachoroidal secretion: extracellular fluid and cerebral
capillaries across the blood-brain barrier.
Amount: the rate of production of CSF
 In adult between 400 to 600 ml per day
 In children 0.2-0.4 ml/min with around 250 ml produced
per day

Background…
 Volume is estimated: 150 ml, with a distribution
of within the:
 Subarachnoid spaces: 125 ml
 Ventricles: 25 ml
 Renewed 4-5 times/ 24 hours in young adults

Mechanism: two steps
1. Passive filtration of plasma:
 From choroidal capillaries to the choroidal
interstitial compartment => pressure gradient.
2. Active transport:
 From the interstitial compartment to the ventricular
lumen => carbonic anhydrase and membrane ion
carrier proteins
Background…

Circulation: is a dynamic phenomenon.
 Circulates from the sites of secretion to the sites
of absorption by:
 In ventricular cavities: unidirectional
rostrocaudal flow
 In subarachnoid spaces: multidirectional flow
 CSF flow is pulsatile=> to the systolic pulse
wave.
Background…

Composition:
 Na, Cl and Mg: higher concentrations
 K and Ca: lower concentrations
Absorption:
 Absorbed into the internal jugular system via cranial
arachnoid granulations (Arachnoid villi)
 The pressure gradient between subarachnoid
spaces and the venous sinus (3 - 5 mmHg)=> CSE
drainage.
Background…

Physio…
Background…

Pathology:
 Any interruption to normal flow, increased production
or decreased reabsorption of CSF =>hydrocephalus
 Types:
 Obstructive (Non-communicating): Blockage in the
fluid pathway of the CSF
 Eg. Arnold – Chiari malformation, aqueductal stenosis
 Non-obstructive: overproduction of the CSF or
Diminished reabsorption
 Eg. choroid plexus papilloma, scarring of arachnoid villi,
Tuberculeous arachnoiditis (Orešković D, Klarica M et al. 2011)
Background…

 The cranial contents: brain tissue (80%), blood (10%) and
CSF(10%).
 Neonates have open cranial sutures and fontanelles => able to
expand in response to rising ICP.
 The accommodation has a maximum limit which once exceeded
will lead to an increase in ICP.
 Posterior fontanelle closes at 2 months of age, and the anterior
fontanelle is closed in most infants by 2 years of age.
 The volume of the cranial vault is fixed once the sutures of the
skull have become fused.
Background…

 Cerebral blood flow (CBF):
 Higher in children compared to adults (100 vs. 50
ml/100g/min).
 Coupled to the metabolic demands
 Autoregulation=> left shift (CPP: 40- 60mmHg)
 PaCO2 reactivity is normal
 ICP:
 In infants: 3 - 4 mmHg
 In adults: 10 - 15 mmHg
Background…
(Vavilala MS, Sulpicio, S.G et al. 2009)

Symptoms and signs of increased ICP:
 Vomiting, irritability, drowsiness, bulging fontanelle,
increasing head circumference,
 Downward gaze of the eyes (“setting sun” sign),
 Cushing’s response (hypertension, bradycardia,
irregular respiration).

Symptoms…signs..
 Long term increases in ICP=> impair neurological
development
 Acute => distortion and displacement of the cerebral
contents (herniation)
 Cerebellar herniation: through foramen magnum -
“coning” - leading to coma, respiratory arrest and death.
 Transtentorial herniation: uncus of the temporal lobe is
pushed down=> compression of the third cranial nerve,
brainstem.
=> Ischemia: focal or global

Surgical management
 Extracranial shunts:
 Ventriculoperitoneal
 Ventriculatrial
 Ventriculopleural
 Endoscopic ventriculostomy

Surgery…mgt
 Endoscopic ventriculostomy: is an alternative to
extracranial shunt placement.
 Allows CSF to bypass the obstruction and restores
normal CSF flow to third ventricle.
 Complications:
 Large volume blood loss => injury to the basilar artery
 Adequate resuscitation materials and warmed fluid
readily available
 Neurologic injury

Perioperative challenges:
 Difficult airway management
 ICP control
 Neurological deficit
 Associated prematurity, and congenital abnormalities.
 Rapid sequence induction and intubation
 Pediatrics concerns
(K Allopi et al. 2014)

Perioperative management of Shunt/ ETV :
 Preoperative assessment:
 Standard anesthetic history
 Associated congenital anomalies (VACTERL)
 Raised ICP
 Level of consciousness
 Neurological deficit
 Recurrent respiratory infections
 Volume status and electrolytes
 Sedative premedication considered carefully

Periop…mgt..
 Intraoperative:
 The method of induction:
 (proprofol 2-4 mg/kg, thiopentone 3-5 mg/kg) vs. Gaseous
induction (sevoflurane or halothane)
 Ketamine should not be used
 Non-depolarising NMB are preferable than Suxamethonium??
 Laryngoscopy and airway manipulation minimized.
 Appropriate sized tracheal tube and Firmly secured with
waterproof tape .

Periop…mgt..
 The aim is to maintain CPP and avoid increases in ICP.
 Hypotension should be avoided
 Maintain normocarbia (EtCO2: 4-4.5 kPa)
 PEEP minimized => avoid venous congestion
 Optimizing venous drainage to increase CPP, reduce
venous bleeding and improve the surgical field.
 The core temperature monitored and normothermia
maintained.
 Judicious amount of normal saline should be used

Periop…mgt..
 Pain mgt: most stimulating parts are initial incision and
tunnelling under the skin.
 A short acting opioid: fentanyl (1-3 mcg/kg) or
remifentanil (1 mcg/kg)
 Increased depth of anesthesia
 Standard monitoring

Periop…mgt..
 Postoperative:
 Extubate once awake
 Post-operative analgesia:
 Infiltration of local anesthetic (bupivacaine: 0.25% (0.5-0.75
ml/kg) and
 PCM suppository (15 mg/kg)
 High doses of long acting opioids avoided
 Shunt complications: Blocked, Septic, Exposed, Over
drainage, Disconnection, Valve malfunction
 Monitored in a suitable environment
(Wu Y et al. 2007)

Anesthetic management of neural defects
congenital anomalies

Introduction:
 Neural defects congenital anomalies occur most
frequently as midline defects along the neural axis
involving the head or spine.
 Defects range from minor bony or soft tissue structure to
major malformations of neural tissue.
 Its incidence is about 0.2 to 5 per 1000 live births.
(Shin M, Besser L et al. 2010)

Pathophysiology:
 Spinal cord development: neurulation and forms the
neural tube
 By approximately the 20th day of gestation
 The ectoderm => neural plate => neural fold => neural
crest=> fuse in the midcervical region => the fusion
continues upward and downward.
(Sadler TW et al. 2006)

Pathophy…
 Neural tube defects result from failure of the neural plate
in 3–4-week-old embryos.
 Encephalocele- brain herniation through cephalad defect
 Spina bifida: the neural tube defect of the spinal cord.
 Two types:
 Spina bifida occulta
 Spina bifida cystica

Pathophy…
 Spina bifida cystica- fusion fails in the midline or caudal
neural groove
 Myelodysplasia- Congenital failure of the neural tube to
close
 Meningocele (20%):
 Herniation of meninges only
 Neurological manifestations usually absent
Meningomyelocele (80%)-
 Contains neural elements along with meninges.
 Majority of defects occur in lumbosacral area.
 Neurological deficits distal to defect are most severe
(Toshimi Horiki et al. 2015)

Pathophy…

Etiology:
 Genetic
Females are more affected
More common in Caucasians and blacks
 Environmental- folic acid deficiency
 Teratogenic drugs- Carbamazapine
 Higher prevalence in lower socio economic groups
(Copp AJ, Adzick NS et al 2015)

Associated anomalies:
 Arnold Chiari II malformation ( 80-90%)
 Hydrocephalus (80%)
 Neurogenic bladder(90%)
 Musculo skeletal defects (club foot)
 Urogenital anomalies
 Facial clefts
 Umbilical hernia
 Congenital heart diseases - rare

Associa… ano…
 Types of Chiari malformations:
 Type I Chiari malformations: caudad displacement of
the cerebellar tonsils below the foramen magnum.
 occur in healthy children without myelodysplasia.
 Chiari type II malformation (Arnold-Chiari malformation):
 Usually present with myelodysplasia.
 Caudal displacement of the cerebellar vermis, the fourth
ventricle, and lower brainstem below the level of the
foramen magnum.
 Cervical cord compression occur.

Clinical features:
 Fluid filled swelling at back
 Paraparesis with muscle wasting
 Sensory symptoms
 Neurogenic bladder and bowel
 Convulsions/ tonic spasms
 Cranial nerve dysfunctions

Complications:
 Rupture of sac during birth process=> cover with sterile
dressing
 CSF leak
 Raised ICP- vomiting, convulsions, altered sensorium,
irritability
 Infection – fever, unconsciousness, altered sensorium
(meningitis)

Diagnosis:
Prenatal:
 Prenatal ultrasound picks up the defect in 100% of the
cases

Management:
 Surgery is mainstay of treatment and includes repair of
the defect and a VP shunt ( if associated with
hydrocephalus)
 Meningomyelocele is repaired within first day or two of
life as an emergency because:
 Rupture of sac
 Spinal cord vulnerable to infection
 Sepsis commonest cause of death

Surgi..mgt…
 Surgery < 24 hours for open defects which minimizes
bacterial contamination and further neurological
damage
 Closed lesions should be operated within 48 hours
 Many cases are now scheduled electively before birth
for repair, because the defect is usually apparent on
prenatal ultrasonography (Adzick NS et al. 2011)

Pre anesthetic Evaluation:
 Assess Neurological impairment including
 Cranial nerve function and ability to protect airway
 Neurological deficits
 Signs of ↑ICP
 Volume status and IV access
 Any drug therapy
 Steroids
 Mannitol, diuretics
 Anti - convulsants

Pre op..evalu..
 Investigations
Hb, Blood Grouping and Cross Matching
X Ray chest, echo,.. ( if required)
 Pre op preparation
 Pre op advice
Explain NPO to parents
Adequate hydration to be maintained
Usually no pre medication is required

Induction of anesthesia:
 Intubation is a challenge
 Supine position:- with sac resting in a donut shaped
cushioned ring or rolled blankets to support the baby’s back
and take pressure off the meningomyelocele.
 Right lateral decubitus position:- defect is too large.
 head held in midline by an assistant
 Difficult airway:- awake intubation with atropine
premedication (20mcg/kg, minimum 0.1 mg) and
preoxygenation
 Succinylcholine can be used.

Maintenance of anesthesia:
 Patient positioning - prone position
 Abdomen should be free=> rolls under chest and pelvis
 Excessive rotation/flexion of the neck avoided 
brainstem compression, rise in ICP
 Extremities relaxed and padded
 Eyes protected with ointment and thick pads

Mainten…anes..
 Ventilation:
 Maintain normocapnia
 Prevent barotrauma
 Avoid prolonged exposure of high FiO2
 Body temperature need to be maintained
 Fluid management
 IV maintenance fluids
 High third space losses
 Blood loss is not excessive ( about 30 ml, or 10% of blood
volume). However if lesion is extensive, blood loss
increases significantly

Post operative care:
 Oxygen therapy
 Nursing in prone/ lateral position
 Pain relief by IV fentanyl, paracetamol suppositories
 Insertion of an epidural catheter by the surgeon under
direct vision can provide a conduit for the
administration of local anesthetics and opioids for the
management of postoperative pain but consider age

Latex allergy:
 Myelodysplasia patients are at high risk of developing
allergic reactions to latex.
 Due to repeated exposure to latex products during
surgery, or repeated bladder catherizations.
 Manifests as hypotension and wheezing with or without
rash
(Cote C, Lerman J et al. 2013)

Latex aller…
 To prevent early sensitization, myelomeningocele
patients should be treated as if they are latex allergic
 Anaphylaxis should always be anticipated
 Treatment – removal of source of latex and
administration of IV fluids and vasopressors

The study showed 50% of the patients a sensitization to
latex and
The increased number of surgical interventions was
associated with a higher risk of becoming sensitized.

References:
 ANAESTHESIA FOR VENTRICULO-PERITONEAL SHUNT
INSERTION ANAESTHESIA TUTORIAL OF THE WEEK 121 8TH
DECEMBER 2008
 Orešković D, Klarica M. Development of hydrocephalus and
classical hypothesis of cerebrospinal fluid hydrodynamics: facts and
illusions. Prog Neurobiol. 2011 Aug;94(3):238-58.
 Kahle KT, Kulkarni AV, Limbrick DD, Warf BC. Hydrocephalus in
children. Lancet. 2016 Feb 20;387(10020):788-99
 Spina Bifida: Background, Pathophysiology, Etiology.
Emedicine.medscape.com. 2019. Available from:
http://emedicine.medscape.com/article/311113-overview
 Textbook of Neuroanesthesia and Neurocritical Care. Volume I
Neuroanesthesia
 Clinical anesthesia/edited by Paul G. Barash . . . [et al.]. – 7th ed
 MILLER’S ANESTHESIA, EIGHTH EDITION

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