TO THE EDITOR: We have read with great attention the article by Doron et al.1 (Doron O, Barnea O, Stocchetti N, et al. Cardiac-gated intracranial elastance in a swine model of raised intracranial pressure: a novel method to assess intracranial pressure–volume dynamics. J Neurosurg. Published online June 5, 2020. doi:10.3171/2020.3.JNS193262). We would like to congratulate the authors. Their paper is very relevant, and we agree with most of the authors’ statements, especially with the description of a possible new model for monitoring intracranial pressure (ICP).
Our team believes that one great global need nowadays is to make ICP monitoring accessible to the largest number of patients possible for use in the treatment of many neurological and clinical diseases, not only neurological injury, because we believe that more widespread use of this method may ensure a better overall prognosis for these patients.
The article in question presents a study that uses small animals and a very small sample, and therefore the scientific evidence for using this ICP model clinically in human patients is still hypothetical. In addition, the method used by the authors of insufflation-deflation of the balloon is able to generate only one mechanism of a pathological process. The study did not define the borderline values of intracranial elastance that are associated with clinical findings. Details about the methodology used are also lacking, as it is still unknown if this method may be adversely affected by other parameters, in addition to the physiological ones already mentioned, like intracranial mass, hydrocephalus, and other clinical conditions.
Despite the search for a numerical limit value for ICP and new alternative models of monitoring, such as volume dynamics, by many in the scientific community,2,3 we believe that the ICP waveform (ICPwf) as a method of assessing and monitoring patients provides more accurate information than just the ICP cutoff number. The use of the ICPwf was associated with intracranial compliance (ICC),4,5 and in 2017 Ballestero et al.6 observed for the first time the relation between the peaks obtained with ICPwf monitoring, the P2/P1 ratio, as a marker for studying hydrocephalus. This waveform can also be used in other cases, such as in patients with neoplasms, contusions, and intracranial trauma, in order to monitor ICC. Thus, the numerical values are more referential than conclusive, due to their variations and the limited information about the outcomes.
Technological advances in the medical field have allowed the creation of a new noninvasive model to monitor ICC, the B4C sensor (Braincare), which Ballestero et al.6 applied in their study. This model includes a tension meter and recorder connected to a mechanical device that touches the scalp surface in the frontoparietal area lateral to the sagittal suture. The ICP monitoring function of this instrument is based on the detection of brief changes in the measurements of the skull that result from pressure changes within it; that is, it relates the deformation of the skull with the detection of changes in mean ICP.6
We believe that this noninvasive ICPwf register technique would be of value to monitor neurocritical patients under various circumstances. Its advantages are affordability, efficiency, and simple and practical handling. Besides that, it does not trigger complications, such as infections or hemorrhages, which are frequent adverse effects from the use of invasive methods to monitoring ICP.
Disclosures
The authors report no conflict of interest.
References
- 1↑
Doron O , Barnea O , Stocchetti N , et al. Cardiac-gated intracranial elastance in a swine model of raised intracranial pressure: a novel method to assess intracranial pressure-volume dynamics . J Neurosurg . Published online June 5, 2020. doi:10.3171/2020.3.JNS193262 .
- 2↑
Alperin NJ , Lee SH , Loth F , et al. MR-Intracranial pressure (ICP): a method to measure intracranial elastance and pressure noninvasively by means of MR imaging: baboon and human study . Radiology . 2000 ;217 (3 ):877 –885 .
- 3↑
Kiehna EN , Huffmyer JL , Thiele RH , et al. Use of the intrathoracic pressure regulator to lower intracranial pressure in patients with altered intracranial elastance: a pilot study . J Neurosurg . 2013 ;119 (3 ):756 –759 .
- 4↑
Okon MD , Roberts CJ , Mahmoud AM , et al. Characteristics of the cerebrospinal fluid pressure waveform and craniospinal compliance in idiopathic intracranial hypertension subjects . Fluids Barriers CNS . 2018 ;15 (1 ):21 .
- 5↑
Westhout FD , Paré LS , Delfino RJ , Cramer SC . Slope of the intracranial pressure waveform after traumatic brain injury . Surg Neurol . 2008 ;70 (1 ):70 –74 .
- 6↑
Ballestero MFM , Frigieri G , Cabella BCT , et al. Prediction of intracranial hypertension through noninvasive intracranial pressure waveform analysis in pediatric hydrocephalus . Childs Nerv Syst . 2017 ;33 (9 ):1517 –1524 .
