Introduction

The intervention of cerebrospinal fluid (CSF) shunting for CSF accumulations has brought about long-term survival and avoidance of disabilities in children suffering from hydrocephalus. Unfortunately, the insertion of inert non-growing hardware in infants and children who are usually very active and can expect to grow 20 to 30 times their birth weight leads to a high rate of shunt complications. Some studies find that 60% or more shunts need revising after several years. The task of the Emergency Physician is to diagnose those complications, commence time critical treatments and refer to a neurosurgical service when appropriate.

Clinical presentation

The developmental stage of the child with a CSF shunt can cause considerable variation in the clinical presentation of shunt complications. The most obvious is the presence of an open anterior fontanelle in infants up to the age of approximately 9 to 18 months. Simply looking and feeling the fontanelle allows an estimation of intracranial pressure. A bulging fontanelle is a highly specific but not very sensitive sign of under-shunting; a sunken fontanelle can be a sign of overshunting.

The cranial sutures in children are not fused and can undergo diastasis due to raised intracranial pressure. The older a child is, the longer and higher the intracranial pressure has to be to cause diastasis. This also means that the head circumference will rapidly increase when there is inadequate shunting. Therefore it is important to measure the occipitofrontal circumference and compare it with previous records if available and plot it on growth centile charts. A head circumference that is rapidly crossing centiles in an upward fashion or a head circumference that is in the very high centile range especially when the other parameters, weight and length, are not, is an indicator of undershunting. Another implication of unfused cranial sutures is that because this allows an increase in cranial volume it retards the rise in intracranial pressure. This may be the reason that small infants present with more non-specific signs and symptoms than older children.

The most common question an emergency physician will have to answer when confronted with a child who has a CSF shunt is ‘Should I refer this patient to the neurosurgical service?’ A recent study by Piatt et al¹ attempted to quantify the power of various symptoms and sign to predict shunt malfunction or infection. Table 8.1.2 shows the strongly predictive signs and symptoms that allow referral to be made on the basis of that single finding. This may be done even before computerised tomography (CT) scanning, as the neurosurgeon may prefer to have the scan done locally to allow for easier comparison with previous scans (see discussion of CT scanning below). Table 8.1.3 shows the signs and symptoms with strong positive predictive power but not strong enough to warrant immediate referral if just one feature is present on its own. Thus in a patient with a ventriculoperitoneal shunt (VPS) who presents with fever alone, an initial general work up for a cause of the fever is warranted and then consideration for referral to neurosurgery made if no definite cause for the fever is found. However, fever with another feature listed in Table 8.1.3,