Pulse pressure waveform in hydrocephalus: what it is and what it isn't

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Apart from its mean value, the pulse waveform of intracranial pressure (ICP) is an essential element of pressure recording. The authors reviewed their experience with the measurement and interpretation of ICP pulse amplitude by referring to a database of recordings in hydrocephalic patients.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The database contained computerized pressure recordings from 2100 infusion studies (either lumbar or intraventricular) or overnight ICP monitoring sessions in patients suffering from hydrocephalus of various types (both communicating and noncommunicating), origins, and stages of management (shunt or no shunt). Amplitude was calculated from ICP waveforms by using a spectral analysis methodology.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>The appearance of a pulse waveform amplitude is positive evidence of a technically correct recording of ICP and helps to distinguish between postural and vasogenic variations in ICP. Pulse amplitude is significantly correlated with the amplitude of cerebral blood flow velocity (R = 0.4, p = 0.012) as assessed using Doppler ultrasonography. Amplitude is positively correlated with a mean ICP (R = 0.21 in idiopathic normal-pressure hydrocephalus [NPH]; number of cases 131; p &lt; 0.01) and resistance to cerebrospinal fluid outflow (R = 0.22) but does not seem to be correlated with cerebrospinal elasticity, dilation of ventricles, or severity of hydrocephalus (NPH score). Amplitude increases slightly with age (R = 0.39, p &lt; 0.01; number of cases 46). A positive association between pulse amplitude and increased ICP during an infusion study is helpful in distinguishing between hydrocephalus and predominant brain atrophy. A large amplitude is associated with a good outcome after shunting (positive predictive power 0.9), whereas a low amplitude has no predictive power in outcome prognostication (0.5). Pulse amplitude is reduced by a properly functioning shunt.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Proper recording, detection, and interpretation of ICP pulse waveforms provide clinically useful information about patients suffering from hydrocephalus.</jats:p></jats:sec>

CSF dynamic analysis of a predictive pulsatility-based infusion test for normal pressure hydrocephalus

“…AMPmean is therefore likely to be low in these patients. The theory that these patients are less likely to respond to shunt surgery is in agreement with our previous findings [32], and it is potentially explained by these patients suffering from large ventricles due to brain atrophy rather than NPH [12].…”

Utilidad de la monitorización de la PIC en pacientes con sospecha de disfunción valvular

“…En los primeros parece más relacionada con los cambios en el volumen sanguíneo cerebral y en los segundos con las cifras de PIC media 2 . Algunos autores han demostrado que la respuesta positiva a la derivación es superior en HCA en aquellos pacientes en los que la amplitud del pulso de la PIC es mayor 7,3 , así como que dicha amplitud se reduce tras la colocación de dispositivos de derivación de LCR 6,3 . En los pacientes de esta serie se aprecia cómo el aumento de la PIC media se correlaciona con mayores diferencias entre los componentes sistólico y diastólico de la PIC.…”

Real-Time Analysis of Intracranial Pressure Waveform Morphology

“…There exists indirect evidence that certain characteristics of ICP slow waves may contain useful information for correctly diagnosing NPH and predicting shunt response. It was recently found that increased ICP pulse pressure amplitude has a predictive value for shunt response [9,57]. In this section, we describe our recent attempt [13] to detect and separate periods of ICP slow waves (BW, "B-wave") from those of flat or nearly flat ICP (NW, "no wave") in an overnight ICP recording.…”