The fontanelle tonometer: a noninvasive method for measurement of intracranial pressure

Anterior fontanelle pressure monitoring for the evaluation of asymptomatic infants with increased head growth rate

We studied non-invasive intracranial pressure monitoring in 20 asymptomatic infants with increased head growth rate. Both basal anterior fontanelle pressure (AFP) traces and occurrence of pressure waves were analysed and compared with normal range values previously established. Eight recordings were classified as pathological; cerebral imaging showed subdural collections or ventricular dilatation in all cases. Five out of these eight infants further developed neurological deficits and/or increase of the ventricular size, and required neurosurgical procedures. Twelve infants had normal AFP traces; six of these had normal cerebral imaging and six showed enlargement of subarachnoid spaces with normal ventricles. All of these 12 patients normalised their head growth rate and remained asymptomatic. This observation suggests that AFP monitoring may be helpful in asymptomatic infants with increased head growth rate to identify a progressive intracranial process and the potential need for a neurosurgical procedure.

Non-invasive measurement of intracranial pressure in the newborn and the infant: the Rotterdam teletransducer

Knowledge of intracranial pressure may be important in many clinical situations in neonates and young infants. The best way to obtain this information would be a non-traumatic procedure. In order to test the reliability of a new fontanometer, the Rotterdam teletransducer, 25 simultaneous measurements of cerebrospinal fluid (CSF) pressure and anterior fontanelle pressure (AFP) were performed. Mean (SD) difference between CSF pressure and AFP was -0.2 (1.8) mm Hg (95% confidence interval from -0.48 to -0.88 mm Hg). The AFP was also measured in 60 healthy children (15 premature, 30 term newborn babies, and 15 infants). The different aspects of AFP were analysed and normal values computed. These results suggest that the Rotterdam teletransducer gives reliable continuous information about intracranial pressure and can be used in clinical practice. Interpretation of AFP plots must take the influence of postconceptional age and the physiological occurrence of pressure waves into account.

Magnetic resonance imaging in pseudotumor cerebri

The pathophysiology of pseudotumor cerebri is unclear, but may relate to an abnormality in water transport in the brain. The authors performed MR imaging in seven children with pseudotumor cerebri; the signal intensity in the white matter was normal in all patients. These data suggest that periventricular brain water content is not increased markedly in children with pseudotumor cerebri. The authors speculate that this may relate to the establishment of an equilibrium between increased resistance to cerebrospinal fluid outflow and increased brain stiffness, occurring as a consequence of increased cerebral blood-volume and/or interstitial pressure.

Strain-gauge fontanometry--an advance in non-invasive intracranial pressure measurement

The validation of a fontanometer based on the strain-gauge principle is described. Fontanelle pressures correlated well with invasively determined cerebrospinal fluid (CSF) pressures in a group of neonates and infants with hydrocephalus. This device, which can be zeroed in vivo, has the additional advantage of a fast response time and allows reliable measurements of spontaneous pulsations and induced changes in CSF pressure. Unlike previously reported devices, the accuracy of this transducer was shown to be independent of external forces.

Value of intracranial pressure monitoring of asphyxiated newborn infants

Twenty-three infants suffering the effects of moderate or severe hypoxic-ischaemic encephalopathy were continuously monitored for intracranial pressure (ICP) by means of a subarachnoid catheter for a total of 1083 hours. Cerebral perfusion pressure (CPP) was also continuously monitored for 21 of the infants. The median age at the start of ICP monitoring was 17 hours, and the opening pressure correlated poorly with maximum sustained pressures. Maximum sustained ICP allowed the infants to be divided into three groups: (1) those with no elevation of ICP (nine), of whom two died and five had a normal outcome; (2) those with sustained rises in ICP which were resistent to treatment (nine), of whom seven died and two survivors are severely handicapped; and (3) those in whom the pressure was elevated but could be controlled medically (five), of whom two survived to be quite normal. No infant with a sustained elevation of ICP of 15mmHg or more survived to be normal, nor any who had had a CPP below 20mmHg for one hour or more. Hypotension was the cause of low CPP in most cases. There was a highly significant correlation between sustained elevation of ICP above 10mmHg and poor outcome, but no correlation between outcome and minimum CPP. It was not possible to predict clinically which infants would develop intracranial hypertension, and some infants with very severe perinatal asphyxia did not develop intracranial hypertension, and some infants with very severe perinatal asphyxia did not develop raised intracranial pressure at any time.

New fontanometer for continuous estimation of intracranial pressure in the newborn

Intracranial pressure was estimated by a new pneumatic applanation fontanometer in babies in intensive care. A close correlation with cerebrospinal fluid pressure was found on 35 separate occasions. In 12 control babies the mean (SD) fontanelle pressure was 5.2 (2.2) cm H2O, in eight with a hypoxic-ischaemic encephalopathy it was 12.6 (4.3) cm H2O, and in nine with post-haemorrhagic hydrocephalus it was 10.8 (4.3) cm H2O. In four babies monitored continuously over seven days the correlation remained good. The fontanometer enables pressure to be monitored accurately, continuously, and non-invasively in neonates at risk of raised intracranial pressure.