Table 1.

Adult Brainstem Gliomas’ main epidemiological, clinical, and histological features.

	Diffuse Intrinsic Low-Grade Gliomas	Enhancing Malignant Gliomas	Focal Tectal Gliomas	Exophytic Brainstem Gliomas	Brainstem Gliomas Associated with Neurofibromatosis Type 1
% of Brainstem gliomas	50%	30%	<5%	rare	extremely rare
Age at diagnosis	20–50 years	>40 years
Prognosis/median survival time	6–7 years	11–12 months	good prognosis, usually stable up to >10 years	good prognosis	good prognosis, usually asymptomatic and stable
Symptoms	cranial nerve palsies, long-tract signs	rapid onset and progression of cranial nerve palsies and long-tract signs	obstructive supra-ventricular hydrocephalus	long-lasting headache and vomiting	asymptomatic. symptomatic: intracranial hypertension, seizures and vision impairment
Epicenter	medulla (60%), pons (30%)	brainstem	midbrain	subependymal tissue adjacent to the floor of the fourth ventricle	brainstem (second most common site after the optic pathway)
Behavior and typical spreading	-infiltrative and causing enlargement of the brainstem and obliteration of adjacent cisterns; -typical spreading along the cerebellar peduncles to the cerebellar hemispheres posteriorly, to the midbrain and thalamus cranially, and to the medulla caudally; -rarely, pontine-centered tumors show an exophytic growth and encase the basilar artery anteriorly	rapidly infiltrative	-commonly small, with no infiltrative behavior; -bulky types: compression of the aqueduct of Sylvius	slow-spreading with a typical exophytic growth, which may cause compression of the brainstem and obstruction of the cisterns	- infiltrative and causing enlargement of the brainstem
Main histological type	low-grade tumors, may evolve into anaplastic astrocytomas and/or glioblatomas	anaplastic astrocytomas, glioblatomas	low-grade tumors	low-grade and high-grade variants	low-grade and high-grade variants