Dr Vandana, cranio spinal irradiation, radiotherapy, medulloblastoma, cancer, radiation, treatment, diagnosis, management, natural history of medulloblastoma, signs & symptoms of medulloblastoma, current approach, future advancements
Text of Diagnosis, Treatment & Management of Medulloblastoma
1. Presented By: Dr. VandanaDeptt. of Radiotherapy CSMMU, Lucknow
The origin of Medulloblastoma is frommedulla( Latin for marrow),blastos(Greek word for germ) andoma( Greek for tumor);
means tumor of primitive undeveloped cells located inside the cerebellum.
Most common malignant primary brain tumor of child age group.
First described byHarvey CushingandPercival Baileyin 1930.
Initially described as spongioblastoma cerebelli - a soft, suckable tumor usually arising in the vermis of cerebellum.
In 1925, changed name to medulloblastoma - from medulloblast - a hypothetical multipotent cell.
A highly malignant primary brain tumor that originates in the cerebellum vermis or posterior fossa.
Arise in cerebellum and projects into 4 thventricle.
Originate from embryonal cells k/a medulloblastof cerebellar stem cells. The exact cell of origin, or medulloblast has yet to be identified.
It is currently thought that it arises from Germinative neuroepithelial cells in the external granular layer of cerebellum.
Posterior fossa contains hindbrain which consists of cerebellum, pons and medulla.
The cavity of hindbrain is fourth ventricle. This is bounded in front by pons and medulla and behind by cerebellum.
Thevermisseparates two lateral lobes or cerebellar hemspheres.
Because of the location of the fourth ventricle, ventral to the cerebellum, mass lesions or swelling of the cerebellum can cause obstructive hydrocepahalus.
Relevant Neuroanatomy 5. CSF Pathways
CSF is producedby modified ependymal cells in choroid plexus
It circulates from lateral ventricles into the third ventricle through the foramen of munro.
It then passes into the fourth ventricle through the narrow cerebral aqueduct.
From the fourth ventricle, it passes slowly through median aperture (foramen of magendie) and lateralforamina (foramen of luschka) and enters the subarachnoid space over brain and spinal cord.
It is reabsorbed into venous sinus blood via arachnoid granulations.
Lateral Ventricle Foramen of Munro Third Ventricle Foramen of Luschka Foramen of Magendie Central canal of Spinal Cord Subarachnoid Space 6. Epidemiology
Overall account~ 7% all braintumors
10-20% of brain tumors in pediatric agegroup
0.4%1% of all adult centralnervous system tumors
40% of tumors of the posteriorfossa
Peak incidence at the age of5 6yrs In children and25yrs in adults
Approximately 20% of Medulloblastoma present in infants younger than 2 years old; .
male : female (3:2)
Figure:Distribution of pediatric central nervous system (CNS) tumors by location in the CNS and by tumor type. 7. Adult vs. Paediatric Medulloblastoma Child Adult Usual age ~ 4 - 8 yrs Median age ~ 24 - 30 yrs Shorter clinical History (~ 3 months) Longer history ( ~ 5 months) Classical type predominates Desmoplastic type relatively commoner Median cerebellar syndrome predominates Lateral cerebellar syndrome seen Biologically more agressive Biologically less aggressive Poorer resectability - median location Greater resectability - lateral location Higher surgical morbidity and mortality Lower surgical morbidity and mortality - impact of location and age Poorer RT tolerance Better RT tolerance Poorer long term survival Better long term survival 8. Natural History Arising in the midline cerebellar vermis (roof of the 4 thventricle) Grows into the 4 thventricle Fills into the 4 thventricle Spread around the 4 thventricle Invasion of ventricular floor Invasion of brain stem Invasion of brachium pontis CSF Spread Extra neural spread :Y oung age, males and diffuse subarachnoid disease 9. Mode of Spread
Floor of forth ventricle
Inf cervical spine
Sup- above tentorium
Extraneural (5%) Most common CNS tumor to spread
MC sites are Long Bones and Ribs(10-15%)
10. Pathological Features
Highly cellular tumor
High N:C ratio
Cells arranged in typical Homer -Wright rosettes
Multiple histological subtypes
Classic medulloblastomas- 70-80%
Medulloblastoma with extensive nodularity (MBEN) - 3%
WHO classification-2007large cell / anaplastic (LCA) 10% to 22%. 11.
Medulloblastoma with extensive nodularity (MBEN):occurs in infants and is associated with a good prognosis.
classic medulloblastoma medulloblastoma with extensive nodularity 12.
Large cell medulloblastoma:Large nuclei, abundant cytoplasm.
These large cells tend to mix with cells with nuclear pleomorphism and k/a anaplastic cells.
Diffuse anaplasia is associated with poor prognosis.
Desmoplastic/nodular: nodular, reticulin-free zones or pale islands. Surrounded by densely packed mitotically active cells.
large cell medulloblastomaanaplastic medulloblastoma 13. Chang Surgical classification 1969T1 Tumour < 3 cm in diameter and limited to classic position in vermis, roof of fourth ventricle, or cerebellar hemisphere T2 Tumour > 3 cm in diameter and further invading one adjacent structure or partially filling the fourth ventricle T3a Tumour further invading two adjacent structures or completely filling the fourth ventricle, with extensions into aqueduct or foramina of Magendie or Luschka with marked internal hydrocephalusT3b Tumour arising from the floor of fourth ventricle or brain stemand filling the fourth ventricle T4 Tumour penetrates aqueduct to involve third ventricle or midbrain or extends to cervical cord No N StageM0 No metastases M1 Microscopic evidence of tumour cells in CSF. M2 Macroscopic metastases in cerebellar and/or cerebral subarachnoid space and/or supratentorial ventricular system M3 Macroscopic metastases to spinal subarachnoidal space M4 Metastases outside the central nervous system 14. Clinical Features
Raised ICT:Due to obstructive or non communicating hydrocephalus
Pressure Syndrome: Nocturnal or morning head-ache, nausea and vomiting and papilledema.
Symptoms usually precede presentation by no more than 2 months.
Presenting symptoms are related to the age of the patient.
infants with open cranial sutures, irritability, anorexia, failure to thrive, macrocephaly and setting sun sign.
The younger, nonverbal patient presents with behavioral changes, listlessness, irritability, vomiting, and decreased social interactions.
Older children and adults complain of headache, especially upon awakening in the morning.
Decerebrate rigidity, head tilt, stiff neck s/o herniation
In children, tumor involve cerebellar vermis causes gaitataxia.
In Adults, desmoplastic variant arises in cerebellar hemisphere causing ipsilateral dysmetria.
Worsening handwriting ,difficulty with hoping or running, slurring speech and hypotonia.
Neighbourhood syndrome :focal deficit due to pressure effect.
Brain stem :diplopia, 6th cranial nerve palsy, positional dizziness, nystagmus, tinnitus, hearing loss, facial sensory and motor loss .