Brain and spinal tumours: Case

Framing the case

This seven-year-old girl has the classic presentation of a posterior fossa tumour with obstructive hydrocephalus. The progressive early morning headache that wakes her from sleep, the vomiting that relieves it, the papilloedema, the false-localising right sixth palsy, and the truncal ataxia with the dysmetria, together make a posterior fossa mass the working diagnosis, and the first decision is to move the child from an elective workup to an emergency resuscitation. The framework that organises the case is the location, the posterior fossa, and the biology, the embryonal medulloblastoma that is the commonest malignant brain tumour of childhood. ^[2][3]

Immediate assessment and stabilisation

The assessment begins with the airway, the breathing and the circulation, and the level of consciousness, because a drowsy child with the papilloedema and the ataxia is at risk of the herniation from the unrelieved hydrocephalus. The child is admitted to a paediatric neuro-oncology centre, and the dexamethasone is started at zero point one to zero point two milligrams per kilogram per dose every six hours to control the vasogenic oedema. The head is elevated, the isotonic fluids are maintained, and the neurosurgical and the oncology teams are alerted. The hydrocephalus is managed with the external ventricular drain at the surgery or before it, because the obstructed cerebrospinal fluid pathway is the immediate threat. ^[11]

The diagnostic pathway

The magnetic resonance imaging of the brain with and without contrast confirms the posterior fossa mass, the oedema, the hydrocephalus and the relationship to the fourth ventricle and the brainstem. The whole neuraxis is imaged at the diagnosis because the medulloblastoma disseminates through the cerebrospinal fluid, and the spinal magnetic resonance shows no drop metastases. The cerebrospinal fluid cytology, sent once the pressure is relieved, shows no malignant cells. The maximal safe resection is performed, and the residual tumour on the postoperative scan measures under one point five square centimetres. The histology confirms the medulloblastoma, and the molecular studies place it in the molecularly average-risk category. ^[3][4]