Anesthesia for Neurosurgery in Infants and Children by sammyc2007

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									Anesthesia for Neurosurgery in Infants and Children
Barbara Van de Wiele, M.D. Los Angeles, California

경희의료원 마취통증의학과 R3 전주연

Introduction
 Age related differences and procedure related issues different from adult neuroanesthesia

Neuroanatomy Neurophysiology Neuropathophysiology Review anesthesia considerations for selected neurosurgical procedures

Neuroanatomy
 Size : Doubles in the first year  Weight : 80% of adult weight by the age of two, larger
percent of TBW(10% vs 2%)

 Skull suture : not fused  Fontanelles
Ant. fontanelles - 2~3month Post. fontanelle – 7~19month.

Open fontanelle
Noninvasive assessment of ICP US imaging of intracranial structures Untreated progressive hydrocephalus Fusion of the skull sutures is not complete until adolescence

Spinal Cord
 Anatomical position
Infants – L3 Adult – L1-2 disk

 Tethered cord
Spinal cord migration hindered (progressive neurologic deficits)
Middline dimple over spine above the gluteal fold (asymptomatic tethered cord) -Increased risk of neurologic injury with regional anesthesia or diagnositic lumbar puncture

Cerebral Blood Flow and Metabolism
 Global cerebral blood flow
neonates < adults < children

 Brain oxygen and glucose utilization
neonates < adults < children

 Autoregulation of CBF in neonate
lower absolute values and over a narrow range Baseline MAP
closer to the lower limit of autoregulation in infants and young children than in older children

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

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 Cushing’s triad

Neuropathology
 Brain tumor
Second m/c malignancy of childhood after leukemia Children supra and infratentorial tumors

 Pediatric brain tumor
Involve midline structures

Neuropharmacology
 Effects of Inhalation anesthetics and IV anesthetics on 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 reactivity plateaus at 30mmHg Epileptiform EEG changes Described in children during sevoflurane anesthesia.(>1.5MAC)

Sedation and Induction
 Risk and benefic of sedation and induction
Case by case basis

 Midazolam premedication
Minimal alteration in vetilation in children

 Induction of the child c intracranial HTN
Ideally accomplished using an IV hypnotic agent, nondepolarizing m. relaxant and adjuvant therapy prior to laryngoscopy.

Fluid Management
 Preop dehydration is common
Isotonic crystalloid
Choice for intraop. maintenance and hydration

Hypotonic fluid (Ringer’s lactate 273mOsm/L)
Exacerbate brain edema

Glucose containing fluid
Increase the risk of neurologic injury

Hypertonic saline
Beneficial in resuscitation after traumatic head injury in children

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 water transport

Position and Venous Air Embolism
 Risk of venous air embolism(VAE)
Supine position
Infants > Adults

Sitting position
Similar in children and adults

 Risk of hypotension with detectable VAE
Greater in children

 Bilat. Jugular venous pressure
Increase cerebral venous pressure in children positioned with the head elevated and may assist locating the source of air entrainment

Ventricular Shunts and Related Procedures
 Hydrocephalus
Surgical treatment
Ventriculoperitoneal, ventriculatrial, ventriculopleural shunts and endoscopic third ventriculostomy

 Acute shunt malfunction in children
Intracranial hypertension and neurologic status deteriorate rapidly.

 Complication of procedure
CSF drainage – abrupt decrease in BP Stimulation of the floor of the third ventriculotomy – high incidence of bradycardia Arrythmia and tachycardia and rare severe Cx.

Craniotomy for Surgical Treatment of Intracranial Vascular disease
 Craniotomy for AVM(arteriovenous malformation)
Infant c large cerebral AVM CHF in neonatal period

 Craniotomy for aneurysm – very rare procedure
Located in the post. circulation

Selective Dorsal Rhizotomy
 Reduce spasticity and improve function with spastic cerebral palsy  Anesthetic consideration
Cerebral palsy, testing for selection of n. roots, postop. pain , low birth weight and IVH GER, poor laryngeal and pharyngeal reflexes, and seizure disorder

 Procedure
Laminectomy, division of post. rootlets (M. relaxant cannot be used) 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

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.

Myelomeningocele Repair
 Protrusion of meninges and dysplastic neural tissue through midline 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

Surgical Treatment of Craniosynostosis
 Definition
Premature fusion of one or more cranial sutures sagittal suture (m/c) Skull growth is restricted and deformity ensues Assoc. with difficult airway management

 Repair
In the first six months (Improves skull geometry and allows for normal brain growth ) Strip craniectomy, calvarial reconstruction and endoscopic craniectomy

 Feature of craniosynostosis
Intracranial hypertension – 23% Elevated ICP – more common in multiple suture
synostosis

Surgical Treatment of Craniosynostosis
 Anesthetic consideration
Major blood loss Multiple suture craniosynostosis repair and calvarial reconstructive 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

Encephalodurosynangiosis
 Moya Moya
Progressive occlusive cerebrovascular Transient or permanent neurologic deficits d/t inadequate cerebral 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 cerebral metabolism assoc. with painful stimuli, By maintaining normacarbia, maintaing systemic blood pr.

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

Neurosurgical Treatment of Pediatric Epilepsy
 Procedure
Temporal lobectomy, Focal cortical resection, callosotomy, hemispherectomy, and placement of vagal n. stimulators

 Anesthetic consideration
Antiepileptic drugs Anticonvulsant and proconvulsant effect Metabolic acidosis
Topiramate – more common in children Ketogenic diet

 Vagal n. stimulation (new treatment)
Refractory to medical treatment Severe bradycardia(1/1000), Hoarseness d/t unilat. Vocal cord paralysis (1%)

Traumatic Brain Injury
 Focused on mitigating secondary insult
Poor outcome
Hypotension(SBP < 50% 70mmHg + 2ⅹage) 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


								
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