Interpretation of Overnight Monitoring of ICP in Shunted
Children: an Observational Study
Martin U. Schuhmann, MD PhD, Leipzig, Germany; Sandeep Sood, MD, Detroit, MI;
Steven D. Ham, DO, Detroit, MI; James P. McAllister II, PhD, Detroit, MI; Zofia
Czosnyka, PhD, Cambridge, United Kingdom; Marek Czosnyka, PhD, Cambridge, United Kingdom
Our intracranial pressure (ICP) overnight monitoring study was conducted to observe patients that visited the office or emergency center with abnormal but unclear symptoms related to their hydrocephalus.

Monitoring ICP overnight can give more information to the physician than a single ICP determination because the software used for monitoring not only gives continuous pressure readings but also analyzes brain physiology. For example, B waves emitted from the brain reflect its compliance and, therefore, help to determine whether the patient should remain/become shunt-dependent. Below is the abstract for this study when it was presented at the Annual Meeting of the AANS/CNS Section on Pediatric Neurological Surgery, December 2-5, 2003, Salt Lake City, Utah.
Abstract
Introduction: A pattern of exaggerated nocturnal ICP dynamic, B, or plateau waves is commonly observed in hydrocephalic children and may manifest as disturbances of CSF compensation. Successful shunting should minimize the occurrence and especially the magnitude of these events. We used computerized ICP overnight monitoring combined with positional maneuvers to verify the feasibility of in-vivo assessment of CSF compensatory reserve and shunt function.
Method: 65 overnight datasets and 25 positional maneuvers from 43 monitoring sessions in 32 hydrocephalic children were analyzed prospectively. All had a history of shunting; 26 patients had shunts in-situ. Mean ICP, magnitude of slow waves, ICP pulse amplitude and RAP coefficient, indicating pressure volume compensatory reserve, were recorded continuously.
Results: Mean ICP was 11.2±SD4.3 mmHg. Time trends of ICP indicated overnight vasogenic dynamics in 52 datasets, manifested by episodes (in periods from 1-3 hours) of increased slow ICP wave amplitudes, associated with an increase in ICP pulse amplitude and a decrease in compensatory reserve (if RAP increased to >+0.6 ). In these periods, mean ICP increased by 53% to 17.1±5.8. Peak ICP exceeded 25 mmHg (mean of 34.5±9.7 mmHg) in 35 datasets, indicating pathological CSF dynamics associated with active hydrocephalus or a malfunctioning shunt. Positional tests suggested shunt overdrainage in 10 patients.
Conclusion: Computerized continuous ICP monitoring can assess shunt functioning and characterize the status of CSF compensation in vivo. It furthermore aids clinicians, nurses and parents with permanent bedside trends. Its overall clinical value should be confirmed by a larger clinical study.