Objective B wave analysis in 55 patients with non-communicating and communicating hydrocephalus

Abstract

Background: B waves, slow and rhythmic oscillations in intracranial pressure (ICP), are claimed to be one of the best predictors of outcome after surgery for normal pressure hydrocephalus (NPH). Object: To determine the relation between the percentage of B waves and outcome in patients with hydrocephalus, and also the diurnal variation of B waves. Methods: ICP and patient behaviour were recorded overnight (17 to 26 hours) in 29 patients with noncommunicating hydrocephalus and 26 with NPH. The B wave activity, measured with an amplitude threshold of 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, and 5.0 mm Hg, was estimated as the percentage of total monitoring time (% B waves) using a computer algorithm, and correlated with postoperative outcome, defined as changes in 12 standardised symptoms and signs. Results: There was no linear correlation between improvement after surgery in the 55 patients and total % B waves, but a correlation was found between improvement and % B waves during sleep (r = 0.39, p = 0.04). The percentage of B waves was the same during sleep and wakefulness, and patients with NPH had the same proportion of B waves as the non-communicating patients. Conclusions: B waves are commonly observed in patients with both communicating and noncommunicating hydrocephalus, but are only weakly related to the degree of postsurgical improvement.

Aqueductal Stroke Volume: Comparisons with Intracranial Pressure Scores in Idiopathic Normal Pressure Hydrocephalus

“…19,40 In this context, the MWA is computed from the single cardiac-induced ICP waves, while B waves are short-lasting (Ͻ 1 minute) increases in static ICP (mean ICP). It has previously been reported that occurrences of B waves and single ICP waves (expressed by the MWA) do not correlate.…”

Adaptive method for assessment of cerebrospinal fluid outflow conductance

“…An aspect which might remedy this is that the magnitude of the ICP variations vary widely between patients [21]. This indicates that the measurement time could be reduced for patients with smaller variations, as compared with patients with larger variations, without reducing the reliability of those investigations.…”

Real-Time Analysis of Intracranial Pressure Waveform Morphology

“…There exists positive [51,52] and negative [53][54][55] evidence that frequent presence of ICP slow waves predicts a positive outcome after shunt implant. ICP slow waves, also known as Lundberg's B-waves, are defined as oscillations with a frequency of 2-0.5/minute and large amplitude [56].…”

“…However, the capability of overnight ICP monitoring to predict shunt response remains controversial. [51,[53][54][55].…”