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27year old male

Brain Stem Glioma(Well Differentiated Astroctyoma)

Brainstem glioma is a generic term for tumors involving the brainstem

Bimodal age distribution, a peak incidence 5-10, and a second peak in the fourth decade.

Approximately 3/4 younger than 20 years.

Approximately 2.4% of all intracranial tumors in adults and 9.4% of intracranial tumors in children

A more indolent course in adults, which are more likely to be low grade and remain localized

Histology

Composed of a heterogeneous group of gliomas

malignant (60-70%) anaplastic astrocytoma, glioblastoma multiforme

low grade (30-40%) astrocytomas (low grade), gangliogliomas, JPA

may be associated with a deletion of chrom. 9p

Grossly, can be broken down into diffuse, focal, or exophytic

Diffuse (60-70%)

most common type of brain stem glioma

arise in the pons

usually anaplastic astrocytoma with poor survival

have symptoms lasting wks -> months (rapid growth)

common triad reflects diffuse brain stem involvement:

ataxia

bilateral dysfunction of the cranial nerves

long tract signs

Focal (10-20%)

isolated cystic or solid tumor in medulla & brain stem

most often low-grade astrocytoma

5 yr survival: 50-60%

more isolated and have protracted symptoms (mo.-> yrs)

behavioral changes with varying combinations of unilateral deficits: - cerebellar

cranial nerves (6th, 7th)

upper motor signs (pyramidal tract signs)

Exophytic

dorsal - penetrate thru the ependymoma into the 4th ventricle causing obstructive hydrocephalus; less malignant pathology with good prognosis

lateral - invade the 7th & 8th CN as they exit the brainstem; mainly malignant with poor prognosis

cervico-involve the cervicomedullary junction; neck pain, dysfunction of the lower CN, medullary spastic quadriparesis; generally low-grade tumor with good prognosis

Imaging Characteristics

commonly solid and infiltrating, with some expansion

Most common located in pons

Hypo to isointense on T1; usually best seen on T2

Contrast enhancement variable

Hard to visualize on CT

Favorable prognostic factors

Neurofibromatosis

symptoms of at least 12 months’ duration before diagnosis

exophytic location,

pathology suggestive of low-grade tumor histology

focal tectal and cervicomedullary tumors

calcification on CT scan.

Poor prognostic indicators

age less than 2 years

multiple brainstem signs

cranial nerve palsies

diffuse intrinsic lesions of the pons

short duration of signs and symptoms prior to the time of diagnosis

high-grade histology on tumor biopsy.

Treatment

Surgery

Diffuse – empirical radiation sometimes without biopsy

Focal - surgery indication for histologic typing, tumor removal, cyst drainage, and relief of obstructed CSF

Exophytic - surgery indicated for all types with same indications as for focal type

Radiation (adjuvant)

doses of >5,000 cGy will increase survival rates

local field radiation since recurrence usually in poster. fossa

Usually used in all cases except if tumor ganglioglioma or JPA

may use hyperfractionated protocol (bid)

Differential Diagnosis

Tuberculosis (most common worldwide)

Lymphoma

Pontine myelinolysis

metastasis

Demyelinating disorders

Rhombic encephalitis (listeria)

Resolving hematoma

infarct

Tuberculosis

Tuberculous meningitis with tuberculoma

Lymphoma

Metastasis

Pontine infarct

Ischemia related to vascular invasion by lymphoma

Hypertensive Hemorrhage

Viral meningoencephalitis

Multiple Sclerosis

Radiation

Hypertension

Toluene ingestion

Central Pontine myelinolysis

Oculomotor Nerve Teratoma

GM2 gangliosidoses (i.e.Tay-sach’s disease)

Amyloidosis