Pediatric Neurosurgery

PEDIATRIC NEURO-ONCOLOGY

WHY DO WE SEE SO MANY BRAIN TUMORS?

Brain tumors are the most common form a solid pediatric cancer(only leukemia and lymphoma are more common), newly diagnosed in approximately 2300 children annually

Treatment for leukemia and lymphoma has lowered their mortality to the point that brain tumors are now the number 1 cause of childhood oncology mortality

SYMPTOMS

  • Severe head and neck pain
  • Nausea/Vomiting
  • Dizziness
  • Balance problems
  • Double or blurred vision
  • Hypersensitivity to bright lights
  • Brain stem findings, e.g. swallowing or breathing difficulties

HISTORY

  • When walked
  • When potty trained
  • Swallowing or respiratory issues
  • Pain(where, when)
  • Feeding
  • Head growth
  • Seizures
  • Motor Skills
    • Gross Motor
    • Fine Motor

PHYSICAL EXAMINATION

  • Gait
  • Reflexes
  • Tone
  • Sensory disturbance (temperature, proprioception)
  • Anterior fontanelle
  • Disc margins
  • Coordination

Rule of Age

  • Tumor could not be there for more than the patient's age + 9 months(gestation)
  • Therefore, the risk of recurrence drops dramatically(essentially to 0) after the patient's age has doubled from the time of diagnosis(= 9 month)

PRE-OPERATIVE PREPARATIONS

  • All patients should have a CBC, CMP, and T&C for at least 2 units PRBCs
  • All patients will need peri-operative anti-biotics(25-50mg/kg IV Ancef, barring allergy)
  • NPO after 0100
  • Maintenance IVF(usually D5NS + 20KCl)
  • All patients need an MRI(usually a head MRI with planning)
  • Stryker is now our intra-operative neuro-navigation system. Fiducials are last generation
  • We will have intra-operative MRI in 12-18 months

FRAMELESS STEREOTAXY

COMPLICATIONS

  • Bleeding/Infection
  • Failure to Re-open CSF Pathways
  • CSF leak
  • Seizures
  • Neurological Dysfunction
  • Cerebellar Mutism

LOCATION OF TUMORS

  • About 2/3 of pediatric brain tumors are posterior fossa and 1/3 are supra-tentorial
  • Posterior Fossa tumors usually present with hydrocephalus symptoms and coordination issues
  • Supra-tentorial tumors will often present with seizures or focal neurological deficit
  • Head-aches are common regardless of location

MEDULLOBLASTOMA

Most Common of the pediatric brain tumors(if supra-tentorial, same pathology = PNET-premature neuro-ectodermal tumor)

Spinal Metastases are common(and ominous). CSF often needs to be obtained via LP post-operatively

Initial Treatment is surgical, with the goals of:

  • Diagnosis
  • Opening of CSF pathways
  • Gross total resection

CEREBELLAR ASTROCYTOMA

  • Second most common type of pediatric brain tumor
    • Primary treatment is surgical
    • Commonly presents with hydrocephalus
    • Rarely metastasize (With gross total resection, there is a >80% chance of surgical cure (particularly in the lower grade tumors, e.g. JPA=Juvenile Pilocytic Astrocytoma)
    • Grade of tumor (I-IV) is directly related to long term prognosis

CEREBELLAR ASTROCYTOMA

EPENDYMOMA

  • Third most common type of pediatric cerebellar tumor
  • Initial treatment is surgical
  • Commonly presents with hydrocephalus
  • Occasionally metastasize
  • Adjuvant treatment (at least XRT) is needed

EPENDYMOMA DIFFUSE (OR MULTI-FOCAL) BRAIN STEM GLIOMA

  • Most common type of pediatric brain stem tumor
  • Initial diagnosis is radiographic
  • Surgery is rarely indicated(if so, only for biopsy)
  • Adjuvant treatment with chemo +/− XRT is of limited utility

SURGICAL TECHNIQUE FOR POSTERIOR FOSSA TUMORS

  • EVD placement
  • Midline sub-occipital incision
  • Sub-occipital Craniotomy
  • Dural opening
  • Resection tumor
  • Opening of obex/CSF pathways
  • Closure of dura using patch(usually autologous muscular fascia)

SUPRA-TENTORIAL GLIOMA

  • Most common type of pediatric cerebral hemisphere tumor
  • Initial treatment is surgical, which is likely curative
  • Adjuvant treatment is rarely indicated
  • Anti-convulsants are continued 6+ months post-operatively

SUPRA-TENTORIAL GLIOMA

CRANIOPHARYNGIOMA

  • Most common type of pediatric cystic supra-sellar tumor
  • Initial treatment is surgical, which is likely curative
  • Adjuvant treatment is rarely indicated
  • Pituitary Dysfunction is common(up to 25%)
  • Visual concern, particularly with peripheral vision due to proximity to optic chiasm

OPTIC GLIOMA

  • Most common with NF-1
    • Initial diagnosis is radiographic
    • Surgical treatment is rarely helpful
    • Adjuvant treatment is usually indicated
    • Pituitary Dysfunction is of concern
    • Visual fields and acuity need to be assess regularly

UNUSUAL TUMORS

  • Choroid Plexus Carcinomas
  • Metastases
  • Germ Cell Tumor
    • Need to send markers, e.g. AFP, HCG

METASTASIS

Several years ago, I published the first documented case of transplacental transmission of metastatic melanoma to the neural axis. The patient was a 7 month old boy who presented with signs and symptoms of elevated intracranial pressure. Magnetic resonance imaging revealed a 5x5x6cm inhomogeneously enhancing posterior fossa mass, filling the fourth ventricle. Posterior fossa craniotomy was performed. Pathology confirmed metastatic melanoma, with pathology identical to his mother's. He received aggressive chemotherapy with repeat resection. He also required a ventriculo-peritoneal shunt for treatment of his hydrocephalus. He lived longer than any other case of trans-placental transmission of metastatic melanoma but ultimately succumbed to the disease, 18 months after his initial presentation.