Saulius Rocka

Erratum to: Optimal differentiation of high- and low-grade glioma and metastasis: a meta-analysis of perfusion, diffusion, and spectroscopy metrics.

Introduction To perform a meta-analysis of advanced magnetic resonance imaging (MRI) metrics, including relative cerebral blood volume (rCBV), normalized apparent diffusion coefficient (nADC), and spectroscopy ratios choline/creatine (Cho/Cr) and choline/N-acetyl aspartate (Cho/NAA), for the differentiation of high- and low-grade gliomas (HGG, LGG) and metastases (MTS).

Association of Severe Traumatic Brain Injury Patient Outcomes With Duration of Cerebrovascular Autoregulation Impairment Events

BACKGROUND Cerebrovascular autoregulation (CA) is an important hemodynamic mechanism that protects the brain against inappropriate fluctuations in cerebral blood flow in the face of changing cerebral perfusion pressure. Temporal CA failure is associated with worse outcomes in various acute neurological diseases. An integrative approach is presently used according to the existing paradigm for the association of series of temporal CA impairments with the outcomes of patients with traumatic brain injury (TBI). OBJECTIVE To explore the influence of the duration of CA impairment events on severe TBI patient outcomes. Patient age was also included in the analysis of the prospectively collected clinical data. METHODS CA monitoring included 33 prospective severe TBI patients. The pressure reactivity index [PRx(t)] was continuously monitored to collect information on the dynamics of CA status and to analyze associations between the duration of the longest CA impairment event and patient outcomes. RESULTS The Glasgow outcome scale and the duration of the longest CA impairment were negatively correlated. The duration of autoregulation impairment significantly correlated with worse outcomes. Multidimensional representation of Glasgow outcome scale plots showed that better outcomes were obtained for younger patients (age < 47 years) and those whose longest CA impairment event was shorter than 40 minutes if PRx(t) was above 0.7 in the CA impairment event. CONCLUSION Unfavorable outcomes for TBI patients are more significantly associated with the duration of the single longest CA impairment episode at a high PRx(t) value, rather than with averaged PRx(t) values or the average time of all CA impairment episodes. ABBREVIATIONS ABP, arterial blood pressureABP(t), continuous reference arterial blood pressureCA, cerebrovascular autoregulationCBF, cerebral blood flowCPP, cerebral perfusion pressureGOS, Glasgow outcome scaleGOSHD, Glasgow outcome scale after hospital dischargeGOS6M, Glasgow outcome scale at 6 months after dischargeICP, intracranial pressureICP(t), continuously monitored intracranial pressureLCAI, longest CA impairmentoptCPP, optimal cerebral perfusion pressurePRx(t), pressure reactivity indexTBI, traumatic brain injury.

Intrathecal Baclofen Therapy for the Treatment of Spasticity in Lithuania

Spasticity of cerebral or spinal origin severely impairs an individuals functional ability and quality of life. Intrathecal baclofen (ITB) therapy via an implantable pump is indicated for use in patients unresponsive to oral antispasmodics. ITB therapy improves the daily caring for and relief of painful spasms. In Lithuania, ITB therapy was introduced in clinical practice just recently. We share our experience of spasticity management with the ITB pump system in five patients at Vilnius University Hospital Santariskiu Klinikos. Four patients had spastic tetraplegia associated with cerebral palsy, and one patient developed spastic paraplegia after a spinal epidural abscess.

Novel Technology of Non-invasive Cerebrovascular Autoregulation Monitoring

A novel technology for non - invasive cerebrovascular auto regulation (CA) status monitoring is presented. This fully non-invasive CA monitor is based on ultrasonic time-of-flight (TOF) measurement of cerebral blood volume pulsations within the brain parenchyma, processing of volumetric waves, and calculation of CA estimation indexes without using any additional arterial blood pressure (ABP) measurements. The CA status is estimated by extracting informative and reference slow waves from non-invasively measured TOF signals and by calculating Pearsons correlation coefficient between these waves as a CA index. The analysis of the signal extracted from the envelope of non-invasively measured pulse waves showed good agreement between this signal and ABP waves (r=0.68). Consequently, it shows that this signal might be used instead of ABP waves as a reference signal for calculation of the CA estimation indexes. Comparative invasive versus non-invasive CA monitoring study of 11 traumatic brain injury patients showed that correlation between invasively measured CA index and fully non-invasively measured CA index (no arterial line) was r=0.75. The proposed innovative CA real-time monitoring method gives us new possibilities to perform estimation of the CA status from intracranial waves only as well as to exclude the ABP lines errors and artifacts from the measurement results.

Non-invasive Cerebrovascular Autoregulation Assessment Using the Volumetric Reactivity Index: Prospective Study

BackgroundThis prospective study of an innovative non-invasive ultrasonic cerebrovascular autoregulation (CA) monitoring method is based on real-time measurements of intracranial blood volume (IBV) reactions following changes in arterial blood pressure. In this study, we aimed to determine the clinical applicability of a non-invasive CA monitoring method by performing a prospective comparative clinical study of simultaneous invasive and non-invasive CA monitoring on intensive care patients.MethodsCA was monitored in 61 patients with severe traumatic brain injuries invasively by calculating the pressure reactivity index (PRx) and non-invasively by calculating the volumetric reactivity index (VRx) simultaneously. The PRx was calculated as a moving correlation coefficient between intracranial pressure and arterial blood pressure slow waves. The VRx was calculated as a moving correlation coefficient between arterial blood pressure and non-invasively-measured IBV slow waves.ResultsA linear regression between VRx and PRx averaged per patients’ monitoring session showed a significant correlation (r = 0.843, p < 0.001; 95% confidence interval 0.751 – 0.903). The standard deviation of the difference between VRx and PRx was 0.192; bias was − 0.065.ConclusionsThis prospective clinical study of the non-invasive ultrasonic volumetric reactivity index VRx monitoring, based on ultrasonic time-of-flight measurements of IBV dynamics, showed significant coincidence of non-invasive VRx index with invasive PRx index. The ultrasonic time-of-flight method reflects blood volume changes inside the acoustic path, which crosses both hemispheres of the brain. This method does not reflect locally and invasively-recorded intracranial pressure slow waves, but the autoregulatory reactions of both hemispheres of the brain. Therefore, VRx can be used as a non-invasive cerebrovascular autoregulation index in the same way as PRx and can also provide information about the CA status encompassing all intracranial hemodynamics.

Response to Dr. Frederick Adam Zeiler

Dear Editor, We are very thankful to Dr. Frederick Adam Zeiler for his comments and interest in our article (Petkus V, Preiksaitis A, Krakauskaite S, Bartusis L, Chomskis R, Hamarat Y, et al. Non-invasive Cerebrovascular Autoregulation Assessment Using the Volumetric Reactivity Index: Prospective Study. Neurocrit Care. 2018 June 27; Epub Ahead of Print). We fully agree that the model of association between VRx and PRx is generally nonlinear [1]. On the other hand, we are using arterial blood pressure (ABP), intracranial blood volume, and intracranial pressure (ICP) slow waves for real-time monitoring of VRx(t) and PRx(t). Amplitudes of all slow waves are much smaller comparing with an interval of mean ABP and mean ICP changes observed during severe traumatic brain injury (TBI) patients’ treatment in neurosurgical intensive care units. Slow waves are almost always observed in a linear part of mean ICP versus mean intracranial volume curve. We appreciate the proposal of Dr. Frederick Adam Zeiler to use more sophisticated statistical analysis in order to evaluate the association between VRx and PRx [1]. We intend to do that and to publish more extended analysis results from our prospectively collected data base of VRx and PRx clinical data. We do not believe that VRx will replace PRx in the near future. Our intent is to apply VRx in clinical fields where invasive PRx monitoring technology is not applicable [2, 3]. We appreciate the excellent idea to validate noninvasive VRx on the Lassen curve [4]. We see the lower limit of cerebrovascular autoregulation according to the Lassen curve in our clinical studies of VRx(t) monitoring data during cardiac surgery with cardiopulmonary bypass and during intensive care of severe TBI patients. We intend to publish an additional article on this aspect of our prospective VRx monitoring studies.

Timing of Surgery for Neurologically Compromised Traumatic Cervical Spine Injuries

Timing of surgical decompression for traumatic cervical spine injuries remains uncertain. Numerous preclinical studies demonstrate the benefit of early decompression, and clinical data are controversial. We review the existing evidence and discuss the effect of timing on clinical, functional, and neurologic outcomes.

Right Median Nerve Electrical Stimulation for Coma Treatment—Recent Experience in Lithuania and the U.S.A.

Everyone knows what consciousness is until he attempts of define it [1]. From the point of view of a psychologist, consciousness, from our natal day, is a teeming multiplicity of objects and relations. What we call simple sensations are results of discriminative attention, often pushed to a very high degree [1]. It is usually associated with the higher mental functions, such as feelings, attitudes and emotions, based on past memories and experience. From the viewpoint of physician, consciousness is the state of the patient’s momentary awareness of self and environment and his responsiveness to external stimulation and inner need [2]. This is the more simple definition, what accents the voluntary response to the environment. The opposite of consciousness is unconsciousness: the state of unawareness of self and environment. Between these two extremes lie various conditions, which have indistinct limits. From the practical point of view of a physician, it is common to speak about the level of consciousness. The level of consciousness (LOS) is described in various scales, with the Glasgow Coma Scale (GCS) used most widely among the neurologists and neurosurgeons [3].