Case Presentation Meningomyelocele

1. Case PresentationMeningomyelocele Moderator : Dr. Shende Presenter : Dr. Puneet www.anaesthesia.co.inanaesthesia.co.in@gmail.com

2. Case • Name: B/o Ashma Praveen • Age : 2 days • Sex : Male • Place : Delhi • Informant : Mother

3. Chief complaints History of presenting illness • Swelling in the back since birth • Swelling in the back since birth, not increasing in size, no discharge from the swelling • No h/o fever, running nose and laboured breathing • No h/o seizures, increase in head size, involuntary movements • No h/o irritability, vomiting (accepting feed normally) • No h/o bowel and bladder incontinence

4. Past history • No h/o yellowish discoloration or bluish discoloration of skin • No h/o seizures, apenic or cyanotic spells

5. Antenatal history • Primi, no h/o fever with rash during 1st trimester, radiation exposure during pregnancy • No h/o drug intake except iron and folic acid supplement • Birth history • Born at term by elective LSCS (short stature) • Cried immediately after birth, passed meconium and urine on D1 • H/o moving all the four limbs • Birth weight 2.5 kg

6. Examination • Child conscious, lying quietly • Moving all 4 limbs • Afebrile • No pallor, icterus, cyanosis • No signs of dehydration • Anterior fontanelle – full • Airway • No obvious facial deformity • Head size -

7. Vital signs • HR 130/min • RR 40/min • Capillary refill time <3 seconds • IV line present

8. Systemic examination • Spine • Swelling in thoracic region (T8-T12) • 2cm in diameter, soft, cystic, compressible, bluish discoloration covered with normal skin • CNS • Moving all four limbs • Tone normal • CVS - S1S2 +, no murmur • RS - B/L air entry + clinically clear • P/A : Soft

9. Provisional diagnosis • Term neonate with swelling in the back T8-T12 region with no neurological deficit most probably unruptured meningomyelocele

10. Investigations • Hb : 15.1 g% • TLC : 11,000 • Platelet : 5.3 x 103 • Blood urea : 38 • Na/K : 142/4.3 • C-X-ray : WNL • USG head : No hydrocephalous • CT head and MRI spine

11. Proposed surgery • Meningomyelocele excision and repair

12. Anaesthetic considerations • Neonatal surgery (airway, thermoregulation) • Positioning (do nut for intubation, prone for surgery) • Volume status (CSF leak, blood loss) • Maintenance, analgesia • Emergence (postop monitoring) • Latex allergy prophylaxis

13. Preoperative management • Informed and written parental consent • NPO x 4 hours for breast milk • Maintenance IV fluids to continue • Premedication – none • Anesthesia machine check • Emergency drugs • Monitors

14. Preoperative management (contd…) • Induction : preoxygenation, fentanyl (5µg) + thiopentone (12.5mg) after confirming ability to ventilate – Atracurium 1.5 mg • IPPV • Airway secured with 3.0 uncuffed ETT fixed at 9 cm • Maintenance O2 + N2O+ isoflurane, fentanyl, atracurium

15. Neural Tube Defects • Meningocele = meninges + CSF • Meningomyelocele = meninges + neural tissue + CSF • Myelocele = neural tissue

17. Neural Tube Defects • Spina Bifida Latin “split spine” • Failure in closure of the neural tube during early embryologic development • Trilaminar embryo day 16-17 gestation • Endoderm → gut • Mesoderm → muscle and skeletal system • Ectoderm → skin & nervous tissue • Neural tube formation days 18-27 • Neural folds fuse in midline days 22-23 • Disjunction of superficial ectoderm from neural tube • Failure of any step → dysraphia → maldevelopment of the neural structures and adjacent mesodermal structures

18. Neural Tube Defects

19. Meningomyelocele

20. Etiology • Nutritional deficiency / Metabolic defect • Folate 0.4mg/day – US Public Health Service • Decrease risk of NTD by ~ 70% • Teratogens • Valproic acid, carbamezapine, cytochalasins, calcium channel blockers • Genetics • Lower risk in blacks(1:3000), increased risk caucasian (1:1000) • Increased risk if previous child with NTD • 1 affected child risk=2-5% • 2 affected children risk 10-15% • Non-Mendelian transmission • Point mutations in folate receptor genes C677G, A127T • MTHF and CT677 mutations → abnormal maternal folate metabolism

21. Diagnosis • Pre-natal ultrasound 18wk GA • Inter-operator variability • Sensitivity increases with risk of NTD • 60% low risk, 89% high risk • α-Fetoprotein levels • Sensitivity 64% • Non-specific • Combined 86% sensitivity Br J Obstet Gynaecol. 1995 May;102(5):370-6.

22. MMC Effects by Organ System • CNS • Open defect → CSF leak → High infection risk → Damage to exposed neural tissue • Depends on level of lesion • Flaccid paralysis below lesion • Sensory deficits • Bladder / Bowel dysfunction • Hydrocephalus (15% at primary closure→ 90% post closure) • VP shunting • Arnold-Chiari Type II malformation • Small posterior fossa • Caudal displacement of cerebellum, medulla, and pons into cervical canal

23. ~80% incidence with MMC ~20% develop symptoms of brainstem dysfunction Dysphagia Poor feeding Recurrent Aspiration Vocal cord paralysis Stridor Apnea Abnormal responses to hypoxia, hypercapnea BEWARE extreme head flexion → brainstem compression Arnold-Chiari Malformation Type II

24. Pulmonary • Sequellae of recurrent aspiration • Possible restrictive pulmonary function post-closure • Kyphoscoliosis • CVS • Congenital cardiac defects ~40%, F>M • Secundum ASD most common then VSD • GI • Neurogenic bowel dysfunction / incontinence

25. GU • Bladder extrophy • Neurogenic bladder dysfunction • Urinary incontinence/obstruction • Recurrent UTIs/pyelonephritis • Bladder dysfunction → chronic vesico-ureteric reflux • Renal dysfunction → ESRD • MSK • Kyphoscoliosis • Clubfoot • Hip dislocation • Flexion Contractures • IMMUNE • High risk population for latex allergy

26. Latex Allergy • Tosi et al. 1993 J Pediatr Orthop reported 40% serologic evidence of sensitivity • Pittman et al. 1995 Pediatr Neuro Surg 50% IgE latex antibodies • Exact cause unknown • Sensitization due to early and repeated exposure with many medical procedures • Spectrum from localized dermatitis, conjunctivitis, rhinorrhea, to anaphylactic shock

27. Latex free medical care • Medic Alert bracelet if sensitized • High suspicion for latex allergy and anaphylaxis

28. Pre-Op Assessment • Pre-natal hx, method of delivery, complications • Gestational Age • Medications – antibiotics re: meningitis • Family history • Physical Exam • Vital signs • Neurologic deficits • Associated anomalies • Volume status ?fluid deficit • Vascular access – adequate? • Investigations • CBC, Lytes, Cr, ABG • Echocardiogram? • Pre-Medication • SBE prophylaxis?

29. Latex free anesthetic – gloves, foleys, stopcocks, medication stoppers • Vascular Access – maintenance + blood products PRN • Monitoring – routine, bladder catheter +/- arterial line / CVC PRN • Warm Room, warming blanket • Positioning • Supine or lateral for induction, airway management • Donut for protection of defect from pressure, trauma if supine • Prone for repair • Induction • Inhalational or IV • Succinylcholine for intubation – not associated with ↑K+ • Endotracheal intubation – armoured ETT

30. Maintenance • Avoid long acting muscle relaxants – neural element identification • Ventilation – may develop restrictive defect with large closure • Volume status • Deficits + maintenance fluid • Blood loss • Replace CSF loss with NS • Emergence • Confirm adequacy of analgesia • Confirm adequate spontaneous ventilation • Beware vocal cord paralysis, stridor • Be prepared for emergent re-intubation • Disposition • ICU setting for post-op monitoring - apneas • Prone or lateral position • Monitoring for CSF leak, infection, hydrocephalus

31. Spinal Anesthesia for Closure of MMC • Viscomi et al. Anes Analg 1995;81:492-5 • Case series • n=14 neonatal lumbo-sacral MMC closures • Prone positioning with chest roll • Hyperbaric tetracaine 0.5% injected at caudal border • Supplemental intrathecal tetracaine infused by surgeon PRN for “crying related to surgical manipulation” • “Fussy” infants given pacifier +/- midazolam for sedation 9/14 • Post-op apnea monitoring x 36 hrs with impedance monitor • Results • Spinal anesthesia 100% successful • Supplemental spinal anesthesia required in 50% @ 93+/-14 minutes • 2 post-op respiratory events correlated to dose of midazolam • Considerations • Contraindicated with local infection • Uncontrolled neonatal airway in prone position

32. Primary Closure of MMC • Emergency neonatal surgery • Goal closure within 24-72hr of delivery • Surgical Goals • Close dural defect and stop CSF leak • Prevent infection • Preserve neural function • Prevent secondary tethering of spinal cord • Surgical Technique • Separate neural placode • Dissection of the dura • Approximation of tissues in midline • Closure of dural sac and skin defect (may require rotational flap if the defect is large)

33. MMC Other Surgical Procedures • VP Shunting • Hydrocephalus 15% at primary closure • 80-90% post-closure • Frequent revisions through childhood • Deterioration in neurological condition – must determine ↑ICP vs. brain-stem compression • Hindbrain decompression • ~20% develop symptoms of brainstem dysfunction • Dysphagia, poor feeding, choking, aspiration, apnea • Posterior fossa decompression • Genitourinary procedures • High incidence of bladder extrophy • Vesicoureteral reflux 2° neurogenic bladder • Urethral dilation • Vesicostomy • Orthopedic Revisions • Club foot • Hip dislocation • Spinal kyphosis

34. Fetal Surgery for MMC Closure • Animal studies suggest in utero closure of MMC defect may • mitigate neurological damage • decreased incidence of hydrocephalus • “Two Hit” Hypothesis • First Hit = failure of neuralation → open defect • Second Hit = amniotic fluid induced spinal cord injury + CSF leak through neural tube defect

35. Fetal Surgery for MMC Closure • Fetal risks • Mortality 4% • Increased risk of: • Oligohydramnios • Pre-term delivery • Low birth weight • Maternal risks • Uterine rupture • Placental abruption • Post-op bowel obstruction www.anaesthesia.co.inanaesthesia.co.in@gmail.com