경희의료원 마취통증의학과 R3 전주연

1. Anesthesia for Neurosurgery in Infants and ChildrenBarbara Van de Wiele, M.D. Los Angeles, California 경희의료원 마취통증의학과 R3 전주연

2. Introduction • Age related differences and procedure related issues different from adult neuroanesthesia • Neuroanatomy • Neurophysiology • Neuropathophysiology • Review anesthesia considerations for selected neurosurgical procedures

3. 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

4. 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

5. 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

6. 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

7. 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

8. Neuropathology • Brain tumor • Second m/c malignancy of childhood after leukemia • Children supra and infratentorial tumors • Pediatric brain tumor • Involve midline structures

9. 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)

10. 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.

11. 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

12. 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

13. 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

14. 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.

15. 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

16. 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

17. 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.

18. 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

19. 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

20. 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

21. 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.

22. 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

23. 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%)

24. 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