Value of brainstem acoustic evoked potentials in posterior fossa tumours in childhood.

Abstract

Brainstem acoustic evoked potentials (BAEPs) were measured in 14 children with different type of posterior fossa tumours several times during the clinical course, in order to assess the value of this simple and non-invasive method in the diagnosis and follow-up of posterior fossa tumours in childhood. Eight children had midline medulloblastoma, three children had lateral astrocytoma, three had intrinsic brainstem glioma. Different BAEP patterns could be detected in different tumour's type: bilateral symmetrical or slightly asymmetrical I-V. IPL prolongation in midline medulloblastomas, unilateral or markedly asymmetrical I.-V. IPL prolongation or wave V. depression on the contralateral side in lateral astrocytomas, and severely distorted asymmetrical waveform in intrinsic brainstem gliomas. The BAEPs were abnormal earlier than CT scan in a case of craniospinal astrocytoma. BAEPs were useful in the follow-up: the effect of the preoperative chemotherapy or the progression of the inoperable tumours could be as well documented by this method, as by the CT scan. BAEPs proved effective in the assessment of postoperative neurological complications: bilateral symmetrical IPL prolongation and wave V. depression with clinical signs of increased intracranial pressure occurred in a case of postoperative occlusive hydrocephalus, unilateral IPL prolongation occurred during irradiation or chemotherapy after medulloblastoma removal as signs of cerebral oedema.