Over the same period improvements in neurosurgical techniques and perioperative care have made surgery feasible for all except diffuse intrinsic tumors [1].

The classically quoted incidence of brainstem tumors in children identifies 70–80 % as diffusely infiltrating lesions (primarily arising in the pons) with the remainder identified as one of the focal or benign tumor types. They arise in the pons and cause diffuse enlargement of the brainstem (Fig. 36.2). Extension to the midbrain and medulla and/or exophytic growth is seen in at least two thirds of cases. The histologies are usually fibrillary astrocytomas with a potential for malignant change and have a very poor prognosis. The most common presenting symptoms for the diffusely infiltrating pontine gliomas include diplopia, motor weakness, and difficulty with speech, swallowing, and walking. Neurologic signs include ataxia, cranial nerve palsies (most commonly pontine nerves followed by the medullary nerves), and long tract signs. Only 10 % of the lesions have hydrocephalus at diagnosis. Tumors of the midbrain and medulla may be diffuse or focal, even diffuse tumors show much less infiltration and expansion of the brainstem than seen with the pontine gliomas.

The duration of symptoms correlates with the type of brainstem glioma. Children with diffusely infiltrating pontine gliomas have a brief history of neurologic symptoms almost appears in weeks and usually less than 6 months. The more focal, less aggressive brainstem tumors are often associated with prolonged symptoms, typically confined to deficits in one or two cranial nerves alone unlike diffusely infiltrating tumors.

MRI is the definitive test for diagnosis and delineation of tumor extent and type. The typical diffusely infiltrating pontine glioma is homogeneous or hypodense on T1 imaging. The tumor expands the pons and infiltrates into other brainstem segments. They are best seen on T2 weighted or FLAIR MRI which should be the imaging modality of choice. There is often little or no enhancement, but inhomogeneous areas of enhancement can be noted [2]. The presence of a ring enhancement is suggestive of high-grade histology. Biopsy of the classic, diffusely infiltrating pontine glioma is generally unnecessary, and there is no clear benefit derived from biopsy when the imaging and clinical picture show a typical diffusely infiltrating tumor. Histological series show equal proportions of low and high grade [3]. There is no consistent correlation between histology and outcome; generally all diffusely infiltrating pontine tumors show poor duration of response to irradiation, and median survival is less than 1 year [4–9]. It is of interest that most such tumors show malignant astrocytoma at autopsy even the ones showing low-grade histology at initial diagnosis.

Brainstem tumors have recently been shown to express ERBB1 with the degree of overexpression is proportional with increasing g grade [10]. These findings suggest that EGFR inhibitors can be worth studying in these kinds of tumors in conjunction with radiation. One of the studies ongoing among the Pediatric Tumor Consortium examines gefitinib and radiation in pediatric patients newly diagnosed with brainstem tumors in a phase I/II manner.

The management of pediatric brainstem gliomas basically depends on the location of the tumor and the specific imaging characteristics of the tumor. Patients with nonenhancing focal tumors in the tectal region who present with only hydrocephalus may do well without any treatment other than CSF diversion. Active intervention including biopsy is reserved for clinical and radiologic progression. Surgery is the treatment of choice for focal tumors at other locations that are surgically accessible (either they extend toward the surface of the brainstem laterally or at the floor of the fourth ventricle) and have imaging characteristics of low-grade histology (uniform bright enhancement with contrast material which correlated with pilocytic histology, the absence of peritumoral hypodensity) as mentioned above. Similar to completely or subtotally resected low-grade gliomas at other sites results can be excellent in a high percentage [3, 11]. Results are less satisfactory for patients with bulky tumors and for patients in the medulla with lower cranial nerve deficits because of high risk of postoperative complication in these cases. For surgically inaccessible focal lesions, conventional radiotherapy should be the standard of care. Looking at the treatment results of the series using conventional radiotherapy in the brainstem tumors, it is reasonable to assume that 50–70 % of focal lesions may be permanently controlled with such treatment [2–4, 9, 12]. Dorsal exophytic lesions are treated with surgery, and ultrasound guidance is used to achieve maximal tumor resection during the procedure. However, as there is no definite interface between tumor and brainstem in most of the cases, there are usually a thin layer of residual tumor cells after the surgery on the floor of the fourth ventricle. Nonetheless there is no standard postoperative radiation therapy for these kinds of tumors as the majority of the children do well following surgery. Radiotherapy should be considered for patients that found to have high-grade lesions or for patients that have low-grade tumors who are found to have progressive disease in the first 1–9 months after the surgery. For patients that recur after this period re-surgery, further surgery should be considered and radiation should be reserved for those who have inoperable disease. According to the literature, the salvage is possible with excellent overall prognosis, especially for dorsal exophytic lesions [11, 13, 14].

Cervicomedullary lesions arise in the upper cervical cord and grow rostrally beyond the foramen magnum, and they are usually low-grade lesions whose axial growth is limited by the pyramidal decussations located at the junction of cervical cord and medulla. The tumor grows posteriorly causing a bulge in the dorsal of medulla toward the fourth ventricle. Surgery is the treatment of choice in these tumors with a gross total resection achieved in 75 % of the cases and subtotal resection in the remaining 25 %. For the typical low-grade lesions, outcomes after surgery are excellent. There is no routine indication for postoperative radiotherapy for these kinds of lesions. Radiation is reserved for surgically inaccessible lesions and high-grade tumors.

Surgery has no role in the management of diffuse intrinsic lesions. Even biopsy is no longer considered as necessary in the context of a typical clinical presentation with the characteristic MRI findings; histology does not affect the outcome of these patients and does not influence the treatment [15, 16]. In conventional radiation, the majority of the patients (75 % and over) with diffuse intrinsic tumors improve clinically. The improvements in signs and symptoms begin after several weeks during and after irradiation. Improvement in MRI has been reported in 30–70 % of children. However, the progression-free interval is short with a median of less than 6 months, and survival is poor with median survival less than 1 year and survival rates at 2 years is less than 20 % [3–5, 7, 12, 17]. Intrinsic focal pontine lesions often must be irradiated at diagnosis because of the neurological signs. With the availability of the precision volume techniques, the risk benefit ratio may favor early intervention in these lesions.