Clinical
Presentation: Four-year-old girl presented with history of dizziness, ataxia, vision problem and vomiting for two months.
Radiological
Findings:
Figure 1:Large hypodense lesion causing diffuse enlargement of the brain stem with no enhancement.
Figure 2: Hypointense mass lesion causing diffuse enlargement of pons with surrounding mass effect causing compression of the 4th ventricle posteriorly. There is tonsillar herniation through foramen magnum due to mass effect.
Figure 3: Mass lesion is showing bright signal on T2 image with encasement of the basilar artery.
Figure 4: Post-contrast images do not reveal any significant enhancement in this mass lesion.
Diagnosis:Diffuse brainstem glioma
Discussion: Brain stem gliomas constitute about 15% of all pediatric CNS tumors with peak incidence between 3 and 10 years of age. These are heterogeneous group of tumors that may be diffuse, focal, dorsally exophytic, or cervicomedullary. These are highly aggressive tumors commonly presenting with symptoms of double vision, weakness, unsteady gait, difficulty in swallowing, headache, dysarthria, nausea, and vomiting. Rarely behavioral changes and seizures may also be seen in children with this tumor. Although no definite familial tendency is known, there is an increased incidence of brainstem gliomas in patients with neurofibromatosis type 1.
Magnetic resonance imaging has emerged as the primary diagnostic modality for brainstem gliomas. MRI multiplanar images assist in the establishment of the tumor diagnosis, identification of tumor epicenter, and prediction of its biological behavior. Diffuse neoplasms tend to smoothly enlarge the affected area without focal areas of exophytic tumor. They are generally poorly marginated and involve more than 50% of the brainstem in the axial plane at the level of maximal involvement. Minimal or no contrast enhancement is seen after gadolinium, although enhancement is commonly seen after radiation therapy. It is difficult to biopsy these lesions because of the proximity of vital structures and thus imaging plays a crucial role in the diagnosis. Focal tumors are generally well marginated and involve less than 50% of brainstem in the axial plane. Focal neoplasms often enhance and have a better prognosis in general than diffuse neoplasms.
Diffuse gliomas are unfortunately the most common brainstem lesions, and they have the worst prognosis among the brainstem gliomas. Most children die within 18 months of diagnosis, which is similar to the clinical course of glioblastoma multiforme. There is no role for radical surgery or biopsy since stereotactic biopsy does not change the management strategy. Radiation and/or chemotherapy are the current mainstays of treatment for diffuse brainstem gliomas. The majority of focal neoplasms are amenable to surgery and longer survival.
References:
Jallo GI, Biser-Rohrbaugh A, Freed D. Brainstem gliomas. Childs Nerv Syst. 2004 Mar; 20(3):143-53. Epub 2003 Dec 11. Review. [Medline]
Allen JC, Siffert J. Contemporary chemotherapy issues for children with brainstem gliomas. Pediatr Neurosurg. 1996;24(2):98-102. [Medline]
Barkovich AJ. Pediatric Neuroimaging, Lippincott Williams & Wilkins, 2000. Chapter 7.
