Brain stem glioma

Brain stem glioma is a rare but highly demanding pathology for neurosurgeon. Brain stem corridor is more demanding surgery.

1. BRAIN STEM GLIOMA 31.08.2016 BRAIN STEM GLIOMA NINAS

2. Key concept MRI can differentiate malignant from benign lesions Trend: lower grade tumors tend to occur in the upper brainstem, and higher grade tumors in the Lower brainstem/medulla Usually presents with multiple cranial nerve palsies and long tract findings. Most are malignant, have poor prognosis, and are not surgical candidates. Role of surgery primarily limited to dorsally exophytic lesions and shunting. 31.08.2016 BRAIN STEM GLIOMA NINAS

3. Brainstem gliomas (BSG) tend to occur during childhood and adolescence (77% are < 20 yrs old T hey comprise 1% of adult tumor BSG are one of the 3 most common brain tumors in pediatrics. 31.08.2016 BRAIN STEM GLIOMA NINAS

4. PRESENTATION Upper brainstem tumors tend to present with cerebellar findings and hydrocephalus Lower brainstem tumors tend to present with multiple lower cranial nerve deficits and long tract finding. 31.08.2016 BRAIN STEM GLIOMA NINAS

5. Due to their invasive nature, signs and symptoms usually do not occur until the tumor is fairly extensive in size.

6. SIGNS AND SYMPTOMS: 1. Gait disturbance 2. Headache 3. Nausea/vomiting 4. Cranial nerve deficits: diplopia, facial asymmetry 5. Distal motor weakness in 30% 6. Papilledema in 50% 7. Hydrocephalus in 60%, usually due to aqueductal obstruction (often late, except with periaqueductal tumors, e.g. below) 8. Failure to thrive (especially in age ≤ 2 yrs ) 31.08.2016 BRAIN STEM GLIOMA NINAS

7. PATHOLOGY Heterogeneous group. There may be a tendency towards lower grade tumors in the upper brainstem (76% were low-grade) versus the lower brainstem (100% of the glioblastomas were in the medulla ) 31.08.2016 BRAIN STEM GLIOMA NINAS

8. LOCATION OF BRAIN STEM GLIOMAS A- tectal glioma   B- focal midbrain tumor  C- focal intrinsic pontine glioma   D- doral / exophytic glioma   E- Diffuse Intrinsic Pontine Glioma   F- focal medullary glioma   G- cervicomedullary glioma

9. A cystic component is seen rarely. Calcifications are also rare. 31.08.2016 BRAIN STEM GLIOMA NINAS

10. Growth patterns that can be identified by MRI that may correlate with prognosis 1. diffuse : all are malignant (most are anaplastic astrocytomas , the rest are glioblastomas ). On MRI these tumors extend into the adjacent region in vertical axis (e.g. medullary tumors extend into pons and/or cervical cord) with very little growth towards obex , remaining intraaxial . 2. cervicomedullary : most (72%) are low-grade astrocytomas . The rostral extent of these tumors is limited to the spinomedullary junction. Most bulge into the obex of the 4th ventricle (some may have an actual exophytic component ). 31.08.2016 BRAIN STEM GLIOMA NINAS

11. 3. focal: extent limited to medulla (does not extend up into pons nor down into spinal cord). Most (66%) are low-grade astrocytomas 4. dorsally exophytic : may be an extension of “focal” tumors . Many of these may actually be low grade gliomas including: a) Pilocytic astrocytomas , b) G angliogliomas : very rare, only 13 cases reported as of 1984. Compared to other BSGs, these patients tend to be slightly older and the medulla is involved more frequently. 31.08.2016 BRAIN STEM GLIOMA NINAS

12. Evaluation MRI The diagnostic test of choice. MRI evaluates status of ventricles, gives optimal assessment of tumor (CT is poor in the posterior fossa) and detects exophytic component. T1WI : almost all are hypointense , homogeneous (excluding cysts). T2WI : increased signal, homogeneous ( excluding cysts ). Gadolinium enhancement is highly variable. 31.08.2016 BRAIN STEM GLIOMA NINAS

13. COMPUTED TOMOGRAPHY Most do not enhance on CT, except possibly an exophytic component. If there is marked enhancement, consider other diagnoses (e.g. high grade vermian astrocytoma). 31.08.2016 BRAIN STEM GLIOMA NINAS

14. Treatment Surgery Biopsy : should not be performed when the MRI shows a diffuse infilt rating brainstem lesion (does not change treatment or outcome). Treatment is usually non -surgical. 31.08.2016 BRAIN STEM GLIOMA NINAS

15. Exceptions where surgery may be indicated: 1. tumors with a dorsally exophytic component2: see below these may protrude into 4th ventricle or CP angle tumor which tend to enhance with IV contrast, tend to be lower grade. 2. some success has been achieved with non- exophytic tumors that are not malignant astrocytomas . (surgery in malignant astrocytomas is without benefit) 3. shunting for hydrocephalus

16. Dorsally exophytic tumors These tumors are generally histologically benign (e.g. gangliogliomas ) and are amen able to radical subtotal resection. Prolonged survival is possible, with a low incidence of disease progression at short-term follow-up . Surgical goals in exophytic tumors include: 1. enhanced survival by subtotal removal of exophytic component broad attachment to the floor of 4th ventricle is typical and usually precludes complete excision (although some “safe entry” zones have been described. An ultrasonic aspirator facilitates debulking . 2. establishing diagnosis: radiographic differentiation of exophytic brainstem gliomas tumors from other lesions (e.g. medulloblastoma , ependymoma and dermoids ) may be difficult. 3. tumors that demonstrate recurrent growth after resection remained histologically benign and were amenable to re-resect ion. 31.08.2016 BRAIN STEM GLIOMA NINAS

17. Complications of surgery generally consisted of exacerbation of pre-operative symptoms (ataxia, cranial nerve palsies) which usually resolved with time. 31.08.2016 BRAIN STEM GLIOMA NINAS

18. Medical Management No proven chemotherapeutic regimen. Steroids are usually administered. In pediatrics , there is some indication of response to temozolomide . 31.08.2016 BRAIN STEM GLIOMA NINAS

19. Radiation Tradition ally given as 45–55 Gy over a six week period, five days per week. When combined with steroids , symptomatic improvement occurs in 80% of patients. Possible improved survival with so called “ hyperfractionation ” where multiple smaller doses per day are used. 31.08.2016 BRAIN STEM GLIOMA NINAS

20. Prognosis Most children with malignant BSG will die within 6–12 months of diagnosis. XRT may not prolong survival in patients with grade III or IV tumors . A subgroup of children have a more slowly growing tumor and may have up to 50% five-year survival. Dorsally exophytic tumors comprised of pilocytic astrocytomas may have a better prognosis. 31.08.2016 BRAIN STEM GLIOMA NINAS