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Anesthesia for

Neurosurgery in Infants and

ChildrenBarbara Van de Wiele, M.D.

Los Angeles, California

R3

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Introduction

Age related differences and procedure related issuesdifferent from adult neuroanesthesia

Neuroanatomy Neurophysiology Neuropathophysiology Review anesthesia considerations for selectedneurosurgical procedures

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Pressure Volume Relationship

ICP Infants : 0~6mmHg

Toddlers : 6~11mmHg

Adolescents : 13~15mmHg

Infants and children Slow inc. in intracranium vol.

: compensated by expansion of the cranium.

Rapid inc. are not well tolerated.

Pressure Volume relationship Proportional to the volume of the neuroaxis

: ICP rises more rapidly in children than adults

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Symptoms of Intracranial Hypertension

Symptom of Increased ICP Neonate and infants

Quite nonspecific : increased irritability and poor feeding

Children Headache on awakening and vomiting

All age group Lethargy, decreased consciousness, loss of upward gaze and

Cushings triad

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Neuropathology

Brain tumor Second m/c malignancy of childhood after leukemia

Children supra and infratentorial tumors

Pediatric brain tumor Involve midline structures

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Neuropharmacology

Effects of Inhalation anesthetics and IV anestheticson CBF and CBV Similar in children and adults

Sevoflurane

less inc. in CBV than halothane Isoflurane, sevoflurane, desflurane

Quantitatively similar effect on CBF

Propofol Dec. CBF velocity in excess of change in MAP consistent

CO2 reactivityplateaus at 30mmHg Epileptiform EEG changes

Described in children during sevofluraneanesthesia.(>1.5MAC)

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Fluid Management

Preop dehydration is common Isotonic crystalloid

Choice for intraop. maintenance and hydration

Hypotonic fluid (Ringers lactate 273mOsm/L)

Exacerbate brain edema

Glucose containing fluid

Increase the risk of neurologic injury

Hypertonic saline

Beneficial in resuscitation after traumatic head injury inchildren

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Diuretics

Mannitol Rapid mannitol administration

Hypotension in children

Recommend rate 0.5gms/kg/20min

Furosemide(0.3~0.4mg/kg) Adjunct to mannitol

Decrease CSF production and improve cellular watertransport

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Ventricular Shunts and Related

Procedures Hydrocephalus

Surgical treatment

Ventriculoperitoneal, ventriculatrial, ventriculopleural shuntsand endoscopic third ventriculostomy

Acute shunt malfunction in children Intracranial hypertension and neurologic status deteriorate

rapidly.

Complication of procedure

CSF drainageabrupt decrease in BP

Stimulation of the floor of the third ventriculotomy high

incidence of bradycardia

Arrythmia and tachycardia and rare severe Cx.

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Craniotomy for Surgical Treatment

of Intracranial Vascular disease

Craniotomy for AVM arteriovenous malformation) Infant c large cerebral AVM

CHF in neonatal period

Craniotomy for aneurysmvery rare procedure Located in the post. circulation

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Selective Dorsal Rhizotomy

Reduce spasticity and improve function with spastic cerebralpalsy Anesthetic consideration

Cerebral palsy, testing for selection of n. roots, postop. pain , lowbirth weight and IVH

GER, poor laryngeal and pharyngeal reflexes, and seizure disorder Procedure

Laminectomy, division of post. rootlets (M. relaxant cannot beused)

Inhalation anesthesia is superior to N2O-propofol M. spasm during stimulation of n. rootlets

Elevation of body temperature Significant postop. Pain

Intrathecal and epidural analgesics

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Encephalocele Repair

Herniation of cranial contents M/C located in the occipital region

Undertaken in the early neonatal period

High incidence of anomalies of other organ system

Anesthetic consideration Avoiding trauma to the lesion during airway management

may be challenging.

Substantial blood loss from vascular structures within

occipital encephaloceles.

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Myelomeningocele Repair

Protrusion of meninges and dysplastic neural tissue throughmidline bony defects of the spine M/C lumbosacral region Neurologic function is impaired distal to the lesion

Repair Early neonatal period

Features Congenital heart defect(ASD) 1/3 Short trachea 1/3 Arnold Chiari malformation present in most pt. with

myelomeningocele

Anesthetic consideration Intraop. N. stimulation

Necessary to reverse neuromuscular blockade.

Significant fluid requirements and transfusion Repair of large lesions

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Surgical Treatment of

Craniosynostosis Anesthetic consideration

Major blood loss

Multiple suture craniosynostosis repair and calvarialreconstructive procedures

Percentage of estimated blood vol. Single strip craniectomy 25%

Metopic craniosynostosis 42%

Bicoronal synostosis 65%

Multiple suture 85%

In excess of 100cc/kg asso. With coagulopathy Endoscopic precedure

Blood loss and incidence VAE reduced

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Encephalodurosynangiosis

Moya Moya Progressive occlusive cerebrovascular

Transient or permanent neurologic deficits d/t inadequatecerebral blood flow

Surgical procedure Transposing the temporal artery to the surface of the brain

via a small craniotomy Stimulate formation of collateral vessels.

Goal of anesthesia Minimize neurologic morbidity

By avoiding agitation, hyperventilation,increase in cerebralmetabolism assoc. with painful stimuli, By maintaining normacarbia, maintaing systemic blood pr.

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Encephalodurosynangiosis

Postop period Risk for cerebral ischemia and stroke (As collateral

circulation develops)

Avoiding dehydration, fever, hyperventilation and agitation

d/t pain Long term prognosis

Excellent in most children after cranial revascularization

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Traumatic Brain Injury

Focused on mitigating secondary insult Poor outcome

Hypotension(SBP < 50% 70mmHg + 2age)

Hypoxemia(PaO2 < 60-65 or SaO2 < 90%)

Cerebral perfusion pr < 40mmHg

Severe elevation in ICP

Guideline Tx of cerebral perfusion pr. And Hypotension

Option Tx of ICP > 20mmHg, correction of hypoxia

Recommended therapy Avoidance of prophylactic hyperventilation