Archives ofDisease in Childhood 1993; 69: 621-624 621 ARCHIVES OF Arch Dis Child: first published as 10.1136/adc.69.6.621 on 1 December 1993. Downloaded from DISEASE IN CHILDHOOD The Jtournal of the British Paediatric Association Annotations Stereotactic techniques for brain biopsies Stereotactic techniques for brain biopsy, as well as for less tumours compared with 40-45O/o in adults.'0 As with all common indications, are now well established in adult intrinsic brain lesions it is our belief that histopathological neurosurgery and are widely applied. In the paediatric age confirmation of the neuroradiological imaging diagnosis is group, however, its potential has yet to be fully realisedl 2 mandatory for rational patient management and for and many paediatric neurosurgical units still have little accurate assessment of any treatment given. Because of the experience with stereotactic techniques. This is disap- common sites of paediatric brain tumours described above pointing as the advantages of minimal brain traumatisation stereotactic methods are a particularly important means of and a high degree of point target accuracy (to within 1-2 obtaining histology. In our stereotactic practice less than mm) have much to commend stereotaxy to a wide variety 10% of procedures are performed on children (7 1% of the of paediatric neurosurgical problems. last 155 cases performed in the 18 months since January Stereotaxy in children requires minimal technical modi- 1992). However when considering the management of fications. Although local anaesthesia may be used in posterior fossa lesions this figure increases to 23%. adults, this is inadvisable in children where compliance Before modem stereotaxy the open methods of obtain- may be more problematic and general anaesthesia should ing tissue from intrinsic brain stem lesions were unreliable always be used. The smaller size of the child's head rarely and of high risk to the child. Conversely some patients http://adc.bmj.com/ causes a problem; indeed the skull reaches 80% of its adult were treated empirically without any attempt to obtain size by the age of 2 years, and most stereotactic frames histology. However, at present the combination of high supply longer skull pins for paediatric uses. For very young quality MRI and computed tomography with stereotactic children, under 2 years of age, where the skull is both small methods provides a safe and reliable method of obtaining and very thin we avoid potential pin trauma to the soft and tissue. There have been two criticisms of stereotactic thin skull by using a plaster of Paris cap which is applied to biopsy in this situation, namely that the small samples are the child's head and the stereotactic frame fixed in turn to not representative of the brain stem lesion'l and that on September 25, 2021 by guest. Protected copyright. it with the 'skull' pins in the normal way. In general any knowledge of the histology does not affect subsequent target within the child's cranium may be reached safely management. 12 We would disagree with both these points; using stereotactic techniques. Stereotactic computed firstly stereotactic biopsies may be positioned exactly to the tomography, magnetic resonance imaging (MRI), and appropriate imaging abnormality (such as computed angiography may all be used to plan surgery. We have tomography contrast enhancement or certain features of found MRI to be particularly useful in the paediatric age MRI), and, especially when the frontal route is used, group because of the large number of lesions in the multiple serial biopsies along the axis of the tumour may posterior fossa requiring biopsy. safely be taken. Secondly in our series of brain stem At present the role of stereotactic neurosurgery in biopsies 15% produced surprising results that changed patients under the age of 16 years is largely within the field subsequent management, though only one (a cryptogenic of paediatric neuro-oncology.38 Approximately 200 paedi- arteriovenous malfunction ifi a 13 year old boy) was in atric intracerebral tumours are diagnosed each year in the the paediatric age group.'3 Furthermore, advanced UK, and such tumours constitute the second commonest histopathological methods, including immunocytochem- childhood cancer behind the haematological malignancies.9 istry and cell culture performed on stereotactic biopsy The range ofpaediatric brain tumours differs from those in samples, have increased significantly the body of scientific adults both with respect to the relative frequency of the knowledge regarding these conditions, particularly as histological types and, partly as a result of this fact, the stereotaxy allows the accurate correlation of histology with intracranial position. Thus, intracranial tumours in adults neuroradiological imaging abnormalities. are supratentorial in approximately 70%, whereas the same Juvenile thalamic gliomas are a poor prognostic group. proportion are infratentorial in children. In addition Radical stereotactic excision of these lesions has been midline tumours in both the infratentorial and supra- attempted by some who have been able successfully to tentorial compartments are commoner in children. Thus reduce the tumour burden with acceptable associated medulloblastomas, pineal region tumours, and intrinsic morbidity,'4 15 although the balance of opinion indicates brain stem tumours are relatively more common. Overall that such aggressive treatment does not affect outcome glial tumours account for 70-80% of paediatric brain significantly. In any case stereotactic biopsy provides a safe 622 2Thomas, Kitchen means of obtaining tissue and thus enabling the clinician to 1 PattisapuJV, Walker ML, Heilbrun MP. Stereotactic surgery in children. PaediatricNeuroscience 1989; 15: 62-5. Arch Dis Child: first published as 10.1136/adc.69.6.621 on 1 December 1993. Downloaded from offer an accurate prognosis for the child. 2 StorrsBB, Walker ML. Use of a computed tomography-guided stereotaxic Stereotactic brachytherapy has been used in children for apparatus in pediatric neurosurgery. Concepts in Pediatric Neurosurgery 1985; 5: 214-23. over two decades in the treatment of cystic craniopharyn- 3 Broggi G, Franzini A, Migliavacca F, Allegranza A. Stereotactic biopsy of but has only been used rarely for other indi- deep brain tumors in infancy and childhood. Childs Brain 1983; 10: giomas,16 92-8. cations,17 though with successful results reported 4 Davis DH, Kelly PJ, MarshWR, Kall BA, Goerss SJ. Computer-assisted It is likely that the use of this technique stereotactic biopsy of intracranial lesions in pediatric patients. Pediatric sporadically.1820 Neuroscience 1988; 14: 31-6. will increase in the future, especially in the treatment of 5 Godano U, Frank F, Fabrizi AP, Ricci FR. Stereotactic surgery in the man- locally recurrent disease after primary treatment. agement of deep intracranial lesions in infants and adolescents. Childs Nerv Syst 1987; 3: 85-8. Though stereotaxy in paediatrics has its main role in 6 Hirsch JF, Sainte-Rose C, Pierre-Kahn A, Renier D, Hoppe-Hirsch E. lesion biopsy the following applications indicate the wide Neurosurgery with craniotomy and CT stereotactic guidance in the treat- ment of intracerebral space-occupying lesions. Childs Nerv Syst 1990; 6: potential of stereotactic techniques. 323-6. In children with slit ventricles stereotactic methods may 7 Kelly PJ. Computer assisted stereotactic biopsy and volumetric resection of pediatric brain tumors. Neurologic Clinics of North America 1991; 9: be used to position the ventricular catheter in shunting 317-36. procedures or to place an Ommaya reservoir where this is 8 Nauta HJW, Briner RP, Eisenberg HM. Computed tomogram-guided stereotactic brain biopsy in the pediatric patient. Pediatric Neuroscience required for intrathecal antibiotics or chemotherapy. In 1985/1986; 12: 63-7. obstructive hydrocephalus stereotactic localis- 9 Till K. Paediatric neurosurgery. Oxford: Blackwell Scientific Publications, aqueductal 1975: 1. ation often accompanied by endoscopic visualisation have 10 Milhorat TH. Pediatric neurosurgery. Philadelphia: FA Davis Company, enabled the floor of the third ventricle to be safely 1978: 211. 11 Rorke LB. To whose advantage is the needle brain biopsy? Pediatric approached via the foramen of Monro and fenestrated in Neuroscience 1985/1986; 12: 193-5. third ventriculostomy procedures.21 12 Packer RJ, Nicholson HS, Johnson DL, Vezina LG. Dilemmas in the man- agement of childhood brain tumors: brainstem gliomas. Pediatr Neurosurg There are occasional cases where stereotactic methods are 1991-1992; 17: 37-43. appropriate in the management of children with medically 13 Kratimenos GP, Thomas DGT. The role of image-directed biopsy in the diagnosis and management of brainstem lesions. Br J Neurosurg 1993; 7: intractable movement disorders secondary to birth injury 155-64. and neonatal hypoxia, particularly of tremor and dystonia 14 McGirr SJ, Kelly PJ, Scheithauer BW. Stereotactic resection of juvenile pilocytic astrocytomas of the thalamus and basal ganglia. Neurosurgery types.2223 Epilepsy is a condition that often affects children. 1987; 20: 447-52. In this age group stereotactic methods have been used 15 Drake JM, Joy M, Goldenberg A, Kreindler D. Computer- and robot- assisted resection of thalamic astrocytomas in children. Neurosurgery 1991; mostly in the removal of epileptogenic lesions, for example 29: 27-33. dysembryoplastic neuroepithelial tumours, cavernomas,2425 16 Backlund EO, Johansson L, Sarby B. Studies on