Medulloblastoma

Introduction

The most common type of primary malignant brain tumor in children is medulloblastoma, in which it accounts for approximately 25% of childhood brain tumors. ^, Medulloblastomas can also occur in adults, but they comprise less than 1% of primary brain tumors, and their incidence decreases with patient age. ^, However, these behave similarly to pediatric medulloblastomas in which the 5-year overall survival rates range from 56% to 84%, median survivals range from 6 to 17.6 years, and the 5-year progression-free survival rates range from 40% to 61%. ^, As with children, the primary prognostic factors are extent of resection and presence of localized (nondisseminated) disease. ^, In this chapter, we present a case of a young adult with medulloblastoma.

Example case

Chief complaint: headaches

History of present illness

A 21-year-old, right-handed man with no significant past medical history presented with headaches. Over the past 4 to 5 months, he has complained of progressive headaches. More recently, he developed nausea and vomiting. He was seen in the emergency room where imaging revealed a brain lesion ( Fig. 31.1 ).

Medications : None.
Allergies : No known drug allergies.
Past medical and surgical history : None.
Family history : No history of intracranial malignancies.
Social history : College student. No smoking or alcohol.
Physical examination : Awake, alert, oriented to person, place, and time; Cranial nerves (CN) II to XII intact; No drift, moves all extremities with full strength; Cerebellar: no finger-to-nose dysmetria, no truncal ataxia.
Magnetic resonance imaging spine : No lesions noted.

	Steven Brem, MD, University of Pennsylvania, Philadelphia, PA, United States	George I. Jallo, MD, Johns Hopkins All Children\x92s Hospital, St. Petersburg, FL, United States	James Rutka, MD, PhD, University of Toronto, Sick Kids Toronto, Canada	Charles Teo, MBBS, University of New South Wales, Sydney, Australia
Preoperative
Additional tests requested	Complete spine MRI	Complete spine MRI	Complete spine MRI Neuroophthalmology evaluation	None
Surgical approach selected	Midline suboccipital craniotomy	Midline suboccipital craniotomy and endoscope-assisted	Midline suboccipital craniotomy	Midline suboccipital craniotomy and endoscope-assisted
Anatomic corridor	Telovelar	Telovelar, possible transvermian	Telovelar	Transvermian
Goal of surgery	Maximal safe resection	GTR	GTR	GTR
Perioperative
Positioning	Prone-concorde	Prone	Prone	Prone
Surgical equipment	Surgical navigation IOM (SSEP, BAERs, cranial nerves 7\x9611) Ultrasonic aspirator	Surgical navigation IOM (MEP, SSEP, cranial nerve 5\x9612 EMG, BAERs) Surgical microscope Ultrasound Nerve stimulator Ultrasonic aspirator Endoscope	IOM Surgical microscope Ultrasonic aspirator	Central line Surgical microscope 30-degree endoscope
Medications	Steroids Mannitol	Steroids	None	Steroids
Anatomic considerations	Structures within floor of fourth ventricle, seventh nerve nuclei	Structures within floor of fourth ventricle	Structures within floor of fourth ventricle	Structures within floor of fourth ventricle, cerebral aqueduct
Complications feared with approach chosen	Hydrocephalus, brainstem injury, cranial neuropathy, pseudomeningocele	Ophthalmoplegia, facial palsy, hearing low, lower cranial nerve dysfunction, truncal/appendicular ataxia, cerebellar mutism	Ophthalmoplegia, facial palsy, dysmetria/ataxia	Brainstem injury
Intraoperative
Anesthesia	General	General	General	General
Skin incision	Midline linear from inion to C2	Midline linear	Midline linear	Midline linear
Bone opening	Suboccipital craniotomy and C1 laminectomy	Suboccipital craniotomy and C1 laminectomy	Suboccipital craniotomy +/\x96 C1 laminectomy	Suboccipital craniotomy and C1 laminectomy
Brain exposure	Cerebellar hemispheres, cerebellomedullary junction	Cerebellar hemispheres, cerebellomedullary junction	Cerebellar hemispheres, cerebellomedullary junction	Cerebellar hemispheres, cerebellomedullary junction
Method of resection	Place EVD, position prone, linear incision from inion to C2, bilateral suboccipital craniotomy from transverse sinus superiorly to posterior lip of foramen magnum inferiorly and make sufficiently wide, Y-shaped dural opening, telovelar approach to fourth ventricle with dynamic retraction under microscopic visualization, goal would be 100% resection, care taken at floor of fourth ventricle, watertight dural closure, reinforce with artificial dural graft, bone flap replacement or titanium mesh cranioplasty	Midline incision, bilateral suboccipital craniotomy and C1 laminectomy, Y-shaped dural opening, unilateral telovelar exposure, identify and ligate tela choroidea and inferior medullary velum, protect spinal canal with cottonoid, internal debulking, identify floor of fourth ventricle, stimulate if any residual remains to identify ability to sharply remove without transgressing floor, Frazier point burr hole and EVD if necessary, inspect for residual with endoscope, watertight dural closure with dural substitute	Midline incision, bilateral suboccipital craniotomy +/\x96 C1 laminectomy, Y-shaped dural opening, tumor should present itself beneath tonsils, telovelar exposure if needed, debulk tumor early with ultrasonic aspirator, identify floor of the fourth ventricle, debulk tumor down to the ventricular floor, if tumor invades floor of ventricle do not transgress floor, remove tumor up to aqueduct, dural closure with dural substitute and Tisseel	Midline incision, limited occipital craniotomy/craniectomy and C1 laminectomy, Y-shaped dural opening monitoring and coagulation of midline and circular sinuses, identification of tumor below vermis and early protection of floor of ventricle, total resection and if necessary, midline split of vermis and endoscopic inspection including lateral recesses
Complication avoidance	EVD, telovelar approach, care at floor of fourth ventricle	Telovelar exposure, identify floor of fourth ventricle, stimulate to identify eloquence, sharply remove from floor, endoscope for inspection	Telovelar exposure, identify floor of fourth ventricle	Early protection of ventricular floor, vermian split if necessary, endoscope for inspection
Postoperative
Admission	ICU	ICU	ICU	ICU
Postoperative complications feared	Hydrocephalus, cranial neuropathy (diplopia, facial diplegia, hearing loss, swallowing difficulty), apnea, pseudomeningocele, ataxia	CSF leak, lower cranial neuropathy (facial weakness, hearing loss, dysphagia), ataxia	CSF leak, hydrocephalus, brainstem injury, cranial nerve palsies	Hydrocephalus
Follow-up testing	MRI within 24 hours after surgery Spinal MRI 2 weeks after surgery	MRI within 48 hours after surgery	MRI within 24 hours after surgery	MRI within 24 hours after surgery
Follow-up visits	1 month after surgery 1 week after surgery with medical oncology 5 weeks after surgery with radiation oncology	14\x9621 days after surgery	4\x966 weeks after surgery	6\x968 weeks after surgery
Adjuvant therapies recommended	STR\x96reduced dose craniospinal radiation with chemotherapy GTR\x96craniospinal radiation, possible proton therapy	STR\x96possible repeat surgery NTR\x96radiation/chemotherapy GTR\x96radiation/chemotherapy	STR\x96possible repeat surgery NTR\x96radiation/chemotherapy GTR\x96radiation/chemotherapy	STR\x96possible repeat surgery NTR\x96per oncology GTR\x96per oncology