Evaluation of venous hypertension in craniosynostosis

Craniosynostosis is defined as the premature fusion of one or more cranial
sutures. Although many theories have been formulated on its aetiology,
definitive answers have not yet been found. One of the most important
consequences of the premature fusion of cranial sutures is a higher chance of
elevated intracranial pressure (ICP).
The old hypothesis stated that elevated intracranial pressure was caused by a
too small intracranial volume due to the synostosis of the cranial sutures and
that the elevated ICP induced the neurocognitive development impairment. Our
ongoing research on this topic has proven this theory wrong: patients have a
normal brain volume and a normal or enlarged intracranial volume. Our current
hypothesis is that elevated ICP is mainly caused by venous hypertension and
local perfusion disturbances of the brain. Additional factors that have a
detrimental effect on ICP are increased cerebrospinal fluid volume and
obstructive sleep apnea, but these are only of significance for patients with
syndromic craniosynostosis.
To prove this theory, this study focuses on intracranial venous haemodynamics.
With the use of a transcranial colour-coded sonography the haemodynamics of the
superior sagittal sinus (SSS) will be evaluated and compared to a control
group. The SSS is the most important venous outflow tract for the brain.
Secondly, by evaluating its haemodynamics before and after surgery the effect
of our surgery on venous haemodynamics can be evaluated. Thirdly, flow
measurements at the level of the jugular veins will be performed in order to
assess the effect of the jugular veins on intracranial venous haemodynamics.
Lastly, this study aims to analyse the relationship between venous
haemodynamics and the occurrence of elevated ICP. Our standard treatment
protocol evaluates patients for signs of elevated ICP. By assessing these data
in relation to the venous haemodynamics measured earlier its relationship can
be clarified.

Primary Objective: To evaluate intracranial venous haemodynamics in single
suture craniosynostosis, and to determine the effect of surgery.
Secondary Objective: Provide insight in the relationship between venous
haemodynamics and intracranial pressure in single suture craniosynostosis.

This will be an observational study: a prospective cohort study with a (nested)
case-control study.

This study proposes to perform two ultrasounds in craniosynostosis patients,
before and after surgery. This does not pose any health risk to the patient. It
does however take time. Performing the complete ultrasound will take
approximately 30 minutes. By planning the ultrasounds together with the routine
follow-up appointments patients will not need to come to the hospital solely
for this study. After the second ultrasound patients will be followed according
to standard treatment protocol.
Control group
The control group will consist of NSOP patients. As said earlier ultrasound
does not pose any health risk to the subject. Inclusion in this study as a
control implies an elongation of two regular hospital visits of 30 minutes.
Benefits
By assessing venous haemodynamics in trigonocephaly and scaphocephaly patients
more insight into the pathophysiology is gained and the effect of our surgery
on intracranial venous haemodynamics can be evaluated. Secondly, the role of
venous haemodynamics in the occurrence of elevated ICP can be analysed.
This provides us with valuable information on the possible causes of elevated
ICP. By identifying these factors at an early age elevated ICP and its long
term consequences can possibly be prevented. Comparison with a well-defined,
representative, control group provides us with valuable information of the
effect of craniosynostosis on intracranial venous haemodynamics. In current
literature such a control group is not available.