Introduction

There is little difference in neuroradiological examination of children and adolescents as compared to that of adults. The main reason to recognize pediatric neuroradiology as a specific entity is the significant difference in the panorama of diseases. Hence, the radiologist must possess good knowledge of the specific pathology that can be encountered in the central nervous system of the neonate, infant and adolescent. Such knowledge is a necessary prerequisite for the ability to practice good pediatric neuroradiology. The radiologist must also remain sensitive to the legitimate needs of the parents of sick and handicapped children, to be given as specific diagnosis as is possible, even if no treatment is available.

Clinical examination of the central nervous system is difficult to perform in children, particularly in the newborn. Various types of neuroradiological investigation have come to play an increasing role in the assessment of children during the last decade. This is particularly true in the newborn with cerebral pathology. The most common indications for neuroradiological investigation of children are the evaluation of psychomotor handicap, epilepsy, cerebral inflammation and when a malignancy is suspected. Tumours of the brain are, next to leukaemia, the most common form of malignancy in children. However, the types of brain tumors found in children are quite different from those found in adult patients in reference to both cell type and localization. Although brain tumors are considered common in children, the actual number is small compared to that of adult patients with this disease. A large number of investigations are carried out on the suspicion of hydrocephalus and as follow-up examinations after shunting. Although cerebrovascular disease is the most common indication for neuroradiological investigation in adult patients, this disease is less common in children. The large group of perinatal cerebral diseases represents a common cause for investigation, unique to the pediatric population.

Spinal tumors and degenerative diseases of the spine are uncommon in children and the main indication for neuroradiological investigation of the spine and its contents in infant and adolescent is the suspicion of a congenital malformation. This situation has a major impact on the choice of imaging modality and on the mode of investigation.

The essence of pediatric neuroradiology is found in choosing the correct imaging modality and the optimal way of performing the investigation. Hence, it is impossible to exclude the presence of a malformed brain on a CT or MR investigation in which the images are degraded by motion. Neuroradiological investigation of a child is an uncommon event in most radiology departments and the general radiologist will have limited experience. However, lack of experience can partly be counter-balanced by careful planning of the examination and by using optimal techniques. The greatest risk for error in interpreting a pediatric neuroradiological investigation lies in incorrectly calling an examination normal rather than as signing the incorrect pathological diagnosis. Thus it might be assumed, that radiological methods including a review of previous films, are unable to provide the correct diagnosis and that further radiological efforts would be considered futile. Neuroradiological investigations of children are usually performed either by adult neuroradiologists or pediatric radiologists and only rarely is a pediatric neuroradiologist available. However, it is always wise to have films reviewed by colleagues more experienced and knowledgeable in the special cerebral and spinal pathology that can be found in children - pediatric neuroradiologists.

It may be true that many diagnoses overlooked by less experienced radiologists may have less or no impact for future treatment of the child but this is poor defence for less than optimal radiology. One should never underestimate the psychological impact of a correct diagnosis even if no treatment is available. The correct diagnosis on a malformation of the brain can have a significant impact of the parent's ability to accept that their child is handicapped. Furthermore, correct diagnosis of a malformation can alleviate much anxiety and worry that certain events in the perinatal period could be associated with the handicap of the child.

A discussion of common clinical problems rather than a systematic review of a variety of pathological entities are therefore appropriate.

Olof Flodmark and Derek Harwood-Nash