Medulloblastoma surgery removes a fast-growing tumor from the cerebellum, relieves hydrocephalus and provides tissue for molecular subgrouping before craniospinal radiotherapy and chemotherapy. The goal is maximum safe removal without injuring the brainstem. At Biruni Hospital in Istanbul, our pediatric neurosurgeons operate with navigation and nerve monitoring, and our neuro-oncology board plans radiotherapy on the Elekta Versa HD and follows each child for years.
About This Department
Pediatric Neurosurgery
Medulloblastoma is the most common malignant brain tumor of childhood. Safe surgery opens the path to radiotherapy, chemotherapy and cure.
Medulloblastoma surgery removes a fast-growing tumor from the cerebellum, the back part of the brain that controls balance and coordination, in children and occasionally in adults. The operation relieves pressure on the brain, provides tissue for the molecular tests that define the tumor's subgroup, and removes as much tumor as is safe before radiotherapy and chemotherapy. Safety comes before the last few millimeters. In 787 patients from 35 centers, removing every visible trace gave no survival advantage over leaving a residue smaller than 1.5 square centimeters once the molecular subgroup was taken into account (Thompson and colleagues, Lancet Oncology, 2016). Children with average risk disease reach five-year event-free survival above 80 percent with modern treatment (Michalski and colleagues, Journal of Clinical Oncology, 2021). This page explains symptoms, tests, hydrocephalus, the operation, speech problems after surgery, molecular subgroups, radiotherapy and chemotherapy, follow-up, and how families from abroad arrange medulloblastoma surgery at Biruni Hospital in Istanbul.
80
Percent or more five-year event-free survival in average risk medulloblastoma
787
Patients showing no survival gain from removing small residues at the cost of brain injury
4
Molecular subgroups that now guide the intensity of treatment
Free
Review of your child's MRI and pathology by our pediatric neuro-oncology board
Medulloblastoma grows from immature cells in the cerebellum, often in the midline near the fourth ventricle, one of the fluid spaces of the brain.
Who it affects
Medulloblastoma at a glance
Feature
Detail
Note
Share of childhood brain tumors
Around one in five
Most common malignant type
Peak age
Three to eight years
Also infants and adults
Spread
Through the spinal fluid to the brain and spine
Checked at diagnosis
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Treatment in three parts
Surgery, then radiotherapy to the brain and spine for children over three or four years, then chemotherapy.
Medulloblastoma grows fast, but it also responds well to radiotherapy and chemotherapy. Most children with average risk disease are cured.
The diagnosis is frightening. A clear plan in the first days, made by an experienced team, makes the biggest difference.
The team
Specialist
Role
When
Pediatric neurosurgeon
Surgery and hydrocephalus care
First days
Pediatric neuro-oncologist
Chemotherapy and overall plan
From diagnosis
Radiation oncologist
Craniospinal radiotherapy
Four weeks after surgery
Neuropathologist
Diagnosis and molecular subgroup
After surgery
Symptoms
How medulloblastoma shows itself
Symptom
Cause
Typical pattern
Morning headache and vomiting
Raised pressure from blocked fluid
Worse on waking, eases later
Unsteady walking, clumsiness
Pressure on the cerebellum
Weeks to months
Double vision, head tilt
Pressure on nerves
Later sign
Large head in infants
Hydrocephalus
Bulging soft spot
Symptoms build over weeks and are mistaken for stomach upsets or migraine at first. Repeated morning vomiting with headache, or new clumsiness, calls for a brain scan.
When to go to the emergency department
Sign
Why
Action
Drowsiness or confusion
Rising brain pressure
At once
Severe headache with vomiting
Rising brain pressure
At once
Sudden loss of vision
Pressure on the optic nerves
At once
Could we have noticed earlier?
Early symptoms of medulloblastoma look like common childhood illnesses, and parents and doctors miss them in many cases. The time to diagnosis rarely changes the outcome as much as the quality of treatment that follows.
Once a scan shows a tumor, children start steroids to reduce brain swelling and are seen by a neurosurgeon the same day.
Tests before surgery
MRI of the whole brain and the whole spine is done before surgery whenever possible, because blood and debris after the operation can mimic tumor spread on spine images.
Tests before medulloblastoma surgery
Test
Purpose
Timing
MRI brain with contrast
Tumor size, position, hydrocephalus
At diagnosis
MRI whole spine
Spread through the spinal fluid
Before surgery
Blood tests
Fitness for surgery
Day before
Eye examination
Swelling of the optic nerve
At diagnosis
A spinal fluid sample, taken by lumbar puncture about two weeks after surgery, looks for tumor cells. Together with MRI, it decides the stage.
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Tumor board
The pediatric neuro-oncology board meets before surgery to agree the plan, including what follows the operation.
Genetic counseling is offered when the tumor type suggests an inherited condition, such as Gorlin syndrome or Li-Fraumeni syndrome.
Staging after surgery
Staging elements
Element
Method
Effect on treatment
Residual tumor
MRI within 48 to 72 hours of surgery
Over 1.5 square centimeters raises the risk group
Spread
Spine MRI and spinal fluid
Metastatic disease needs more intensive treatment
Biology
Histology and molecular subgroup
Defines risk
Hydrocephalus
Most children with medulloblastoma have hydrocephalus at diagnosis, because the tumor blocks the flow of spinal fluid out of the fourth ventricle. Steroids reduce swelling, and removing the tumor reopens the pathway in many children.
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Temporary drain
A thin tube placed into the ventricle at the start of surgery drains fluid and controls pressure for several days.
Some children still need a permanent solution after surgery, either an endoscopic third ventriculostomy, which creates a new pathway for fluid inside the brain, or a shunt that drains fluid to the abdomen.
Will our child need a shunt for life?
Many children do not. When hydrocephalus persists after tumor removal, an endoscopic third ventriculostomy avoids a shunt in a good share of them. When a shunt is needed, it is checked at each visit and replaced if it blocks.
What parents can expect
The first week moves fast.
Scans, steroids, the meeting with the neurosurgeon, the operation and the first days in intensive care all fall within a few days of diagnosis, and families face decisions with little time to think, so we give each family one named contact, explain each step in plain words with an interpreter when needed, and write down the plan for the weeks that follow, from pathology results to the start of radiotherapy. Parents stay with the child before anesthesia and in the room throughout the stay.
Questions are welcome at every step.
The operation
A typical operation
Step
What happens
Time
Anesthesia and positioning
Child lies face down, head fixed
One hour
Opening
Incision at the back of the head, small bone window
Thirty minutes
Tumor removal
Microscope, navigation, monitoring
Three to five hours
Closing
Bone replaced, skin closed
One hour
The surgeon opens the back of the skull and reaches the tumor between the two halves of the cerebellum, through the natural space below them, called the telovelar approach, or through the midline. Neuronavigation, nerve monitoring of the brainstem and ultrasound guide the removal.
The brainstem lies directly in front of the tumor. Where the tumor sticks to it, the surgeon leaves a thin layer rather than risk injury.
Children wake in the pediatric intensive care unit and stay one to two days.
Most go home seven to ten days after surgery.
An MRI within 48 to 72 hours confirms how much tumor was removed.
How much tumor to remove
Extent of resection in 787 patients
Comparison
Progression-free survival
Overall survival
Complete against near-complete removal
No difference
No difference
Complete against residue over 1.5 square centimeters
Benefit, mainly in group 4
No significant difference
WNT, SHH and group 3 tumors
No benefit from more removal
No benefit
Older studies treated any residual tumor as high risk, which pushed surgeons toward aggressive removal. The international analysis that took molecular subgroup into account showed that maximum safe resection remains the goal, but chasing small residues at the cost of brain injury does not improve survival (Thompson and colleagues, 2016).
Second surgery
When the early MRI shows a residue larger than 1.5 square centimeters that can be removed safely, a second look operation is discussed before radiotherapy.
What decides the extent
Factor
Effect
Example
Attachment to the brainstem
Leave a thin layer
Floor of the fourth ventricle
Molecular subgroup
More removal helps some groups
Group 4 with metastases
Child's age
Protect function in infants
Radiotherapy delayed
Speech and mutism after surgery
Speech after posterior fossa surgery, 426 children in 26 European centers
Finding
Result
Note
Speech impairment after surgery
30 percent
Mutism or severely reduced speech
Mutism
14 percent
Starts within the first days
Medulloblastoma against benign astrocytoma
2.85 times the risk
Midline tumors carry more risk
Telovelar against transvermian approach
No significant difference
Approach not the main factor
Cerebellar mutism syndrome causes loss of speech, irritability, poor swallowing and unsteadiness one to two days after surgery. Younger age, midline location and medulloblastoma raised the risk in the European cohort, while the surgical route did not (Grønbæk and colleagues, Lancet Child and Adolescent Health, 2021).
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Recovery
Speech returns in nearly every child. In the European cohort, half of the children with mutism were speaking again around 16 days after it began, and others needed weeks to months.
Speech and language therapy, physiotherapy and swallowing support start in the first days, and parents learn ways to communicate while speech returns.
Can we prevent mutism?
No technique removes the risk. Careful handling of the cerebellar pathways, avoiding unnecessary retraction and leaving tumor on the brainstem when needed lower it. We explain the risk before surgery so that families recognize it if it happens.
Some children keep subtle problems with speech fluency, coordination or attention, and our rehabilitation team follows them closely.
Molecular subgroups
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Four groups
WNT, SHH, group 3 and group 4 medulloblastoma differ in age, behavior and outlook, an international consensus agreed in 2010 (Taylor and colleagues, Acta Neuropathologica, 2012).
What each group means
Medulloblastoma subgroups
Subgroup
Typical patient
Outlook
WNT
School age children and teenagers
Excellent, trials test lighter treatment
SHH
Infants and adults, some with inherited syndromes
Variable, depends on TP53
Group 3
Infants and young children, MYC amplification in some
Poorest, intensive treatment
Group 4
Most common, all ages
Intermediate
Tumor tissue goes for molecular testing in a reference laboratory. Results arrive within two to three weeks and refine the risk group before radiotherapy starts.
Treatment is adjusted to subgroup in current protocols, intensified for very high risk tumors and studied for reduction in WNT tumors.
Why tissue quality matters
A well preserved tumor sample, frozen and fixed in the operating room, is needed for these tests, and our surgeons and neuropathologists prepare the samples together during the operation.
Radiotherapy
Reduced volume and reduced dose radiotherapy, average risk medulloblastoma
Comparison
Five-year event-free survival
Conclusion
Boost to tumor bed only
82.5 percent
Not inferior
Boost to whole posterior fossa
80.5 percent
Standard before the trial
Low dose craniospinal, 18 Gy, young children
71.4 percent
Inferior to 23.4 Gy at 82.9 percent
Craniospinal radiotherapy
Radiotherapy treats the whole brain and spine, because medulloblastoma spreads through the spinal fluid, with a higher dose to the tumor bed. It starts within four weeks of surgery and runs daily for about six weeks. The American trial showed that a smaller boost volume is safe, while lowering the craniospinal dose in young children lowered survival (Michalski and colleagues, 2021).
Our radiation oncology team plans craniospinal radiotherapy on the Elekta Versa HD linear accelerator, with image guidance at each session and play specialists who help young children lie still without anesthesia when possible.
Children receive weekly vincristine during radiotherapy, and blood counts are checked every week.
Chemotherapy and young children
After radiotherapy, six to nine months of chemotherapy follow, with cisplatin, vincristine and lomustine or cyclophosphamide.
Chemotherapy side effects we watch for
Effect
Cause
Protection
Hearing loss
Cisplatin
Hearing tests before each cycle, dose changes
Low blood counts and infection
All drugs
Blood tests, fever plan
Kidney strain
Cisplatin
Fluids and kidney tests
Children under three to four years are treated without craniospinal radiotherapy or with delayed radiotherapy, because radiation affects the developing brain most at this age. Intensive chemotherapy, sometimes with high dose chemotherapy and stem cell rescue, and chemotherapy into the spinal fluid replace it in selected children.
Each young child's plan depends on subgroup and spread. We discuss the balance between cure and long-term effects openly.
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Shared care
Chemotherapy can be given in Istanbul or at home with the same protocol, with scans reviewed by our board.
Follow-up and late effects
Follow-up after medulloblastoma treatment
Test
How often
Purpose
MRI brain and spine
Every three months in years one and two, then less often
Tumor return
Hearing tests
Yearly
Cisplatin effects
Growth and hormone tests
Yearly
Pituitary and thyroid effects of radiotherapy
Neuropsychology
At set ages
Learning and memory
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Hormones
Radiotherapy can reduce growth hormone and thyroid function, and replacement treatment restores normal growth in many children.
Most relapses appear within the first three years. Follow-up continues into adulthood for late effects.
Learning and memory can be affected after radiotherapy, especially in younger children. Early neuropsychological testing allows school support before problems grow.
Second tumors
Long-term survivors have a small risk of a second tumor in the radiotherapy field, which is one reason follow-up continues for life.
Back to school
Return to school gives back a normal life.
Most children return to school during or after chemotherapy, at first part time, and our teachers and psychologists prepare a report for the school on fatigue, hearing, attention, balance and the support the child needs in class, from seating at the front to extra time in examinations, while physiotherapy continues for balance and coordination problems that remain after surgery. Brothers and sisters receive support too.
Children adapt, with the right help.
For families from abroad
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Length of stay
Surgery and recovery take two to three weeks. Radiotherapy adds six weeks, and families planning both in Istanbul should expect two to three months. Fitness to fly follows wound healing and stable hydrocephalus.
Send MRI images of the brain and spine with reports, any operation notes and pathology reports, and a summary of symptoms. Medulloblastoma needs prompt treatment, and the board reviews new cases within one working day.
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After you return home
Chemotherapy and scans continue with your local team, and our neuro-oncology board reviews MRI and results by video and message.
One coordinator from the international patients office handles arrangements from the first message through discharge and answers the same WhatsApp number after you return. The office works in English, Arabic, French, Russian, Serbian, Romanian and Spanish and books interpreters for other languages, and it arranges the visa invitation letter, airport transfers, daily transport and accommodation near the hospital. Halal, vegetarian and diabetic meals, a prayer room on site, and a female physician on request wherever the rota allows.
Traveling with raised brain pressure
Children with hydrocephalus and symptoms should not fly until pressure is controlled. We then advise immediate treatment at the nearest neurosurgical center, keep in contact with its team and coordinate transfer to Istanbul as soon as the child is stable enough to travel safely.
Families staying for radiotherapy can rent apartments near the hospital, and siblings can join.
Cost
The quote follows the plan the neuro-oncology board proposes and lists surgery, hospital stay, radiotherapy and chemotherapy separately. We send it in writing after reviewing MRI and reports, before you travel.
Compare quotes for the same plan, and check that intensive care, early MRI, molecular testing and rehabilitation are included.
Thompson EM, Hielscher T, Bouffet E, et al. Prognostic value of medulloblastoma extent of resection after accounting for molecular subgroup, a retrospective integrated clinical and molecular analysis. Lancet Oncol. 2016;17(4):484-495.
Grønbæk JK, Wibroe M, Toescu S, et al. Postoperative speech impairment and surgical approach to posterior fossa tumours in children, a prospective European multicentre cohort study. Lancet Child Adolesc Health. 2021;5(11):814-824.
Michalski JM, Janss AJ, Vezina LG, et al. Children's Oncology Group phase III trial of reduced-dose and reduced-volume radiotherapy with chemotherapy for newly diagnosed average-risk medulloblastoma. J Clin Oncol. 2021;39(24):2685-2697.
Taylor MD, Northcott PA, Korshunov A, et al. Molecular subgroups of medulloblastoma, the current consensus. Acta Neuropathol. 2012;123(4):465-472.
Editor's note
Written by the Biruni Hospital medical editorial team. Reviewed by Assistant Professor Kamil Değer DEVECİOĞLU, Pediatric Surgery.
