Quantitative pupillometry, a new technology: normative data and preliminary observations in patients with acute head injury. Technical note

Comparison of ultrasonographic versus infrared pupillary assessment

OBJECTIVES

To evaluate the correlation between ultrasonographic and infrared pupillary assessments in critically ill patients, including neurocritically ill patients.

DESIGN

Prospective, observational study.

SETTING

Tertiary teaching hospital intensive care unit (ICU) in Montevideo, Uruguay.

PATIENTS

Twenty-six adults patients with age 18 or older admitted to the intensive care unit with and without neurologic pathology. A total of 212 pupillary measures were made between ultrasonographic pupillary assessment (UPA) and infrared pupillary assessment (IPA).

INTERVENTIONS

This was a study that utilized non-invasive (minimal risk) ultrasonographic and infrared pupillary assessment in patients admitted to the ICU. Time between UPA and IPA in a single patient was consistently less than 3 min.

MEASUREMENTS AND MAIN RESULTS

There was a strong positive association between UPA and IPA (right eye [OD]: r = de 0.926, p-value < 0.001; left eye [OS], r = 0.965, p-value < 0.001), also observed in the group of neurocritically ill patients (OD: r = 0.935, p-value < 0.001; OS: r = de 0.965, p-value < 0.001). Taking IPA as reference measure, the percent error for all subjects was 2.77% and 2.15% for OD and OS, respectively, and for neurocritically ill patients it was 3.21% and 2.44% for OD and OS, respectively.

CONCLUSIONS

Ultrasonographic pupillary assessment is strongly correlated with infrared pupillary assessment in critically ill patients, including neurocritically ill patients. Ultrasonographic pupillary assessment is a quick, feasible, non-invasive method that allows accurate pupillary assessment, particularly neurologic function, in patients in whom a more precise measurement of the pupil is required or eye opening is not possible (e.g., periorbital edema due to traumatic brain injury).

Automated Pupillary Measurements Inversely Correlate With Increased Intracranial Pressure in Pediatric Patients With Acute Brain Injury or Encephalopathy

OBJECTIVES

The purpose of this study was to determine correlation and temporal association between automated pupillary measurements and intracranial pressure in pediatric patients with brain injury or encephalopathy requiring intracranial pressure monitoring. We hypothesized that abnormal pupillary measurements would precede increases in intracranial pressure.

DESIGN

A prospective cohort study was performed. Automated pupillometry measurements were obtained at the same frequency as the patients' neurologic assessments with concurrent measurement of intracranial pressure, for up to 72 hours. Pupillary measurements and the Neurologic Pupil index, an algorithmic score that combines measures of pupillary reactivity, were assessed for correlation with concurrent and future intracranial pressure measurements.

SETTING

Single-center pediatric quaternary ICU, from July 2017 to October 2018.

PATIENTS

Pediatric patients 18 years or younger with a diagnosis of acute brain injury or encephalopathy requiring an intracranial pressure monitor.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Twenty-eight patients were analyzed with a total of 1,171 intracranial pressure measurements. When intracranial pressure was elevated, the Neurologic Pupil index, percent change in pupillary size, constriction velocity, and dilation velocity were significantly lower than when intracranial pressure was within normal range (p < 0.001 for all). There were mild to moderate negative correlations between concurrent intracranial pressure and pupillary measurements. However, there was an inconsistent pattern of abnormal pupillary measurements preceding increases in intracranial pressure; some patients had a negative association, while others had a positive relationship or no relationship between Neurologic Pupil index and intracranial pressure.

CONCLUSIONS

Our data indicate automated assessments of pupillary reactivity inversely correlate with intracranial pressure, demonstrating that pupillary reactivity decreases as intracranial pressure increases. However, a temporal association in which abnormal pupillary measurements precede increases in intracranial pressure was not consistently observed. This work contributes to limited data available regarding automated pupillometry in neurocritically ill patients, and the even more restricted subset available in pediatrics.

Validation of Noninvasive Absolute Intracranial Pressure Measurements in Traumatic Brain Injury and Intracranial Hemorrhage

BACKGROUND

Increased intracranial pressure (ICP) causes secondary damage in traumatic brain injury (TBI), and intracranial hemorrhage (ICH). Current methods of ICP monitoring require surgery and carry risks of complications.

OBJECTIVE

To validate a new instrument for noninvasive ICP measurement by comparing values obtained from noninvasive measurements to those from commercial implantable devices through this pilot study.

METHODS

The ophthalmic artery (OA) served as a natural ICP sensor. ICP measurements obtained using noninvasive, self-calibrating device utilizing Doppler ultrasound to evaluate OA flow were compared to standard implantable ICP measurement probes.

RESULTS

A total of 78 simultaneous, paired, invasive, and noninvasive ICP measurements were obtained in 11 ICU patients over a 17-mo period with the diagnosis of TBI, SAH, or ICH. A total of 24 paired data points were initially excluded because of questions about data independence. Analysis of variance was performed first on the 54 remaining data points and then on the entire set of 78 data points. There was no difference between the 2 groups nor was there any correlation between type of sensor and the patient (F[10, 43] = 1.516, P = .167), or the accuracy and precision of noninvasive ICP measurements (F[1, 43] = 0.511, P = .479). Accuracy was [-1.130; 0.539] mm Hg (CL = 95%). Patient-specific calibration was not needed. Standard deviation (precision) was [1.632; 2.396] mm Hg (CL = 95%). No adverse events were encountered.

CONCLUSION

This pilot study revealed no significant differences between invasive and noninvasive ICP measurements (P < .05), suggesting that noninvasive ICP measurements obtained by this method are comparable and reliable.

Multimodal non-invasive assessment of intracranial hypertension: an observational study

BACKGROUND

Although placement of an intra-cerebral catheter remains the gold standard method for measuring intracranial pressure (ICP), several non-invasive techniques can provide useful estimates. The aim of this study was to compare the accuracy of four non-invasive methods to assess intracranial hypertension.

METHODS

We reviewed prospectively collected data on adult intensive care unit (ICU) patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), or intracerebral hemorrhage (ICH) in whom invasive ICP monitoring had been initiated and estimates had been simultaneously collected from the following non-invasive indices: optic nerve sheath diameter (ONSD), pulsatility index (PI), estimated ICP (eICP) using transcranial Doppler, and the neurological pupil index (NPI) measured using automated pupillometry. Intracranial hypertension was defined as an invasively measured ICP > 20 mmHg.

RESULTS

We studied 100 patients (TBI = 30; SAH = 47; ICH = 23) with a median age of 52 years. The median invasively measured ICP was 17 [12-25] mmHg and intracranial hypertension was present in 37 patients. Median values from the non-invasive techniques were ONSD 5.2 [4.8-5.8] mm, PI 1.1 [0.9-1.4], eICP 21 [14-29] mmHg, and NPI 4.2 [3.8-4.6]. There was a significant correlation between all the non-invasive techniques and invasive ICP (ONSD, r = 0.54; PI, r = 0.50; eICP, r = 0.61; NPI, r = - 0.41-p < 0.001 for all). The area under the curve (AUC) to estimate intracranial hypertension was 0.78 [CIs = 0.68-0.88] for ONSD, 0.85 [95% CIs 0.77-0.93] for PI, 0.86 [95% CIs 0.77-0.93] for eICP, and 0.71 [95% CIs 0.60-0.82] for NPI. When the various techniques were combined, the highest AUC (0.91 [0.84-0.97]) was obtained with the combination of ONSD with eICP.

CONCLUSIONS

Non-invasive techniques are correlated with ICP and have an acceptable accuracy to estimate intracranial hypertension. The multimodal combination of ONSD and eICP may increase the accuracy to estimate the occurrence of intracranial hypertension.

Effects of Mild Traumatic Brain Injury on Stereopsis Detected by a Virtual Reality System: Attempt to Develop a Screening Test

Purpose

The study aimed to evaluate stereopsis as a surrogate marker for post-concussion oculomotor function to develop an objective test that can reliably and quickly detect mild traumatic brain injuries (TBI).

Methods

The cohort of this prospective clinical study included 30 healthy subjects (mean age 25 ± 2 years) and 30 TBI patients (43 ± 22 years) comprising 11 patients with moderate TBI and 19 patients with mild TBI. The healthy subjects were examined once, whereas the TBI patients were examined immediately after hospitalization, at 1 week, and at 2 months. A virtual reality (VR) program displayed three-dimensional rendering of four rotating soccer balls over VR glasses in different gaze directions. The subjects were instructed to select the ball that appeared to be raised from the screen as quickly as possible via remote control. The response times and fusion abilities in different gaze directions were recorded.

Results

The correlation between stereopsis and TBI severity was significant. The response times of the moderate and mild TBI groups were significantly longer than those of the healthy reference group. The response times of the moderate TBI group were significantly longer than those of the mild TBI group. The response times at follow-up examinations were significantly shorter than those immediately after hospitalization. Fusion ability was primarily defective in the gaze direction to the right (90°) and left (270° and 315°).

Conclusions

TBI patients showed impaired stereopsis. Measuring stereopsis in different positions of the visual field using VR can be effective for rapid concussion assessment.

A Systematic Review Assessing the Current State of Automated Pupillometry in the NeuroICU

The aim of this study was to assess the current state of automated pupillometry technology and its application in the neurointensive care unit (neuroICU). We performed a literature search using the PubMed, MEDLINE, and EMBASE databases from database inception through a search end date of October 18, 2018, to identify studies reporting on the use of automated pupillometry in the care of critically ill patients with neurological impairment. Two independent reviewers reviewed all titles and abstracts in two filtering phases. Data were extracted independently. One hundred and forty-one articles/abstracts have been published on the use of automated pupillometry in critical care since inception of the PubMed, MEDLINE, and EMBASE databases. We selected and reviewed 22 full-text articles and 8 abstracts, of which 26 were prospective, 2 were retrospective, and 2 were larger case series. Automated pupillometry increased precision, reliability, and reproducibility compared with the manual pupillary examination; detected subtle and early pupillary changes; detected pupillary changes that indicate a rise, or impending rise, in intracranial pressure detected level of analgesia and depth of sedation; served as a prognostic indicator; estimated the clinical severity of aneurysmal subarachnoid hemorrhage; and served as a noninvasive monitor of response to osmotic therapy. At present, no consensus guidelines exist endorsing routine use of automated pupillometry in the neuroICU. However, an increasing quantity of research supports the usefulness of automated pupillometry in this setting. Further large-scale prospective studies are needed before updated consensus guidelines recommending widespread adoption of automated pupillometry are produced.

Establishing a normative database for quantitative pupillometry in the pediatric population

BACKGROUND

Pupillary evaluation is a crucial element of physical exams. Noting size, reactivity, and consensual response is critical in assessing for optic nerve dysfunction. We aim to establish normative data for scotopic pupillary size and function in the pediatric population in a clinical setting.

METHODS

Pupillometry was obtained prospectively for consecutive, normal patients < 18 years old being evaluated by Lurie Children's Ophthalmology. Quantitative data included maximum (MAX) and minimum (MIN) diameters, constriction percentage (CON), latency (LAT), average (ACV) and maximum (MCV) constriction velocities, average dilation velocity (ADV), and 75% recovery time (T75). Iris color was noted as light, intermediate, or dark.

RESULTS

196 eyes of 101 participants (42.6% male, ages 1-17 years, average age 10.3 years) were analyzed. Mean MAX was 6.6 mm (5.1-8.1 mm 95% CI); MIN was 4.7 mm (3.1-6.1 mm 95% CI); CON was 30% (17-42 95% CI); LAT was 230 milliseconds (160-300 ms 95% CI); ACV was 3.70 mm/sec (2.21-5.18 mm/sec 95% CI); and ADV was 0.88 mm/sec (0.38-1.38 mm/sec 95% CI). Age had a positive correlation with MAX, MIN, and CON. 84.2 and 95.8% of participants showed resting pupil asymmetry of ≤0.5 mm and ≤ 1.0 mm, respectively.

CONCLUSIONS

Quantitative pupillometry can be a useful tool for screening pediatric patients. We sought to establish normative data in this group. We found males to have significantly greater MCV and CON than females (p < 0.05). Also, age had a positive correlation with MAX, MIN, and CON.

Early outcome prediction with quantitative pupillary response parameters after out-of-hospital cardiac arrest: A multicenter prospective observational study​

We aimed to determine the characteristics of quantitative pupillary response parameters other than amplitude of pupillary light reflex (PLR) early after return of spontaneous circulation (ROSC) and their implications for predicting neurological outcomes early after cardiac arrest (CA). Fifty adults resuscitated after non-traumatic out-of-hospital CA from four emergency hospitals were enrolled. Pupil diameters, PLR, constriction velocity (CV), maximum CV (MCV), dilation velocity (DV), latency of constriction, and Neurological Pupil index (NPi) were quantitatively measured at 0, 6, 12, 24, 48, and 72 h post-ROSC using an automated pupillometer. Change over time of each parameter was compared between favorable (Cerebral Performance Category [CPC] 1 or 2) and unfavorable neurological outcome (CPC 3–5) groups. Prognostic values of 90-day favorable outcome by these parameters and when combined with clinical predictors (witness status, bystander cardiopulmonary resuscitation, initial shockable rhythm, implementation of target temperature management) were tested. Thirteen patients achieved favorable outcome. CV, MCV, DV (P < 0.001), and NPi (P = 0.005) were consistently greater in the favorable group than in the unfavorable outcome group. Change over time was not statistically different between the groups in all parameters. CV, MCV, DV (ρ = 0.96 to 0.97, P < 0.001, respectively), and NPi (ρ = 0.65, P < 0.001) positively correlated with PLR. The prognostic value of 0-hour CV (area under the curve, AUC [95% confidence interval]: 0.92 [0.80–1.00]), DV (0.84 [0.68–0.99]), and NPi (0.88 [0.74–1.00]) was equivalent to that of PLR (0.84 [0.69–0.98]). Prognostic values improved to AUC of 0.95–0.96 when 0-hour PLR, CV, DV, or NPi was combined with clinical predictors. The 0-hour CV, MCV, and NPi showed equivalent prognostic values to PLR alone/in combination with clinical predictors. Using PLR among several quantitative pupillary response parameters for early neurological prognostication of post-CA patients is a simple and effective strategy.

Neuromonitoring of delirium with quantitative pupillometry in sedated mechanically ventilated critically ill patients

BACKGROUND

Intensive care unit (ICU) delirium is a frequent secondary neurological complication in critically ill patients undergoing prolonged mechanical ventilation. Quantitative pupillometry is an emerging modality for the neuromonitoring of primary acute brain injury, but its potential utility in patients at risk of ICU delirium is unknown.

METHODS

This was an observational cohort study of medical-surgical ICU patients, without acute or known primary brain injury, who underwent sedation and mechanical ventilation for at least 48 h. Starting at day 3, automated infrared pupillometry-blinded to ICU caregivers-was used for repeated measurement of the pupillary function, including quantitative pupillary light reflex (q-PLR, expressed as % pupil constriction to a standardized light stimulus) and constriction velocity (CV, mm/s). The relationship between delirium, using the CAM-ICU score, and quantitative pupillary variables was examined.

RESULTS

A total of 59/100 patients had ICU delirium, diagnosed at a median 8 (5-13) days from admission. Compared to non-delirious patients, subjects with ICU delirium had lower values of q-PLR (25 [19-31] vs. 20 [15-28] %) and CV (2.5 [1.7-2.8] vs. 1.7 [1.4-2.4] mm/s) at day 3, and at all additional time-points tested (p < 0.05). After adjusting for the SOFA score and the cumulative dose of analgesia and sedation, lower q-PLR was associated with an increased risk of ICU delirium (OR 1.057 [1.007-1.113] at day 3; p = 0.03).

CONCLUSIONS

Sustained abnormalities of quantitative pupillary variables at the early ICU phase correlate with delirium and precede clinical diagnosis by a median 5 days. These findings suggest a potential utility of quantitative pupillometry in sedated mechanically ventilated ICU patients at high risk of delirium.

Interrater reliability in pupillary assessment among intensive care nurses

BACKGROUND

Pupillary abnormalities are a common and reliable finding of brain herniation, ischaemia, and acute brain injury in critically ill patients. Reliable pupil assessment is a vital evaluation in diagnostic and therapeutic procedures for neurocritical patients.

AIM

To evaluate inter-rater reliability of pupillary assessment among intensive care.

METHODS

In this prospective, blind observational study, intensive care nurses and two researchers evaluated the pupil size, reactivity and symmetry of 200 patients with neurosurgery or neurological diseases. A total of 200 pupillary measurement sets were completed independently and blindly.

RESULTS

Three observers -two researchers and the nurse- found fair-to-good and excellent agreements in initial pupil size evaluations of right and left pupils, respectively (ICC = 0.70, 95%; ICC = 0.75, 95%). In patients with pupil size ≥4 mm, the observers found fair-to-good agreements in both right and left pupil initial size measurements (ICC = 0.52; ICC = 0.65). Agreement in pupil symmetry was moderated (K = 0.58), and reactivity was near perfect (K = 0.89) between the three observers.

CONCLUSION

Although the two researchers found near perfect agreement in pupil size, symmetry and reactivity assessment, two researchers and the nurse found moderate agreement in pupil symmetry and fair-to-good agreement in pre- and post-light stimulation pupil size.

Eyelid squinting improves near vision in against-the-rule and distance vision in with-the-rule astigmatism in pseudophakic eyes: an eye model experimental study

Background

To elucidate whether eyelid squinting improves near and distance vision in against-the-rule (ATR) and with-the-rule (WTR) simple myopic astigmatism in pseudophakic eyes.

Methods

A refraction-model eye was mounted on a wavefront analyzer. The eyelid fissure was simulated using a slit placed horizontally in front of the model eye. Four different refractive statuses [− 1.50 diopters (D) and − 3.00 D of both WTR and ATR simple myopic astigmatism] were set using cylindrical lenses. For each refractive status (emmetropia, − 1.50 D WTR, − 1.50 D ATR, − 3.00 D WTR, and − 3.00 D ATR astigmatism), wavefront aberrations were measured, both with and without the slit, 40 times each.

Results

The 2 mm horizontal slit caused a hyperopic focus shift (+ 6.69 μm) in − 1.50 D WTR astigmatism, whereas, in − 1.50 D ATR astigmatism, it caused a myopic focus shift (− 2.01 μm). The astigmatism was decreased in the ATR astigmatism groups and increased in the emmetropia and WTR astigmatism groups, respectively. Total aberrations were decreased in the emmetropia and WTR astigmatism groups and increased in the ATR astigmatism groups. When the reference plane was set to the near plane, total aberrations were decreased in the ATR astigmatism groups.

Conclusion

As the horizontal slit was placed in front of the model eye, the focus moves nearer in ATR astigmatism and farther in WTR astigmatism. These effects of eyelid cause improvement of near vision of pseudophakic eyes with ATR astigmatism.

Using Pupillary Pain Index to Assess Nociception in Sedated Critically Ill Patients

BACKGROUND

Pupillary reflex dilation is a reliable indicator of response to noxious stimulation. In a proof of concept study, we investigated the performance of pupillary pain index, a new score derived from pupillary reflex dilation measurements, to predict nociceptive response to endotracheal suctioning in sedated critically ill patients.

METHODS

Twenty brain-injured and 20 non-brain-injured patients were studied within 48 hours of admission (T1) in the intensive care unit and at 48-72 hours later (T2). Video-based pupillometer was used to determine pupillary reflex dilation during tetanic stimulation. The tetanic stimulation (100 Hz) was applied to the skin area innervated by the ulnar nerve and was stepwise increased from 10 to 60 mA until pupil size had increased by 13% compared to baseline. The maximum intensity value allowed the determination of a pupillary pain index score ranging from 1 (no nociception) to 9 (high nociception). The Behavioral Pain Scale response to endotracheal suctioning was measured thereafter.

RESULTS

Behavioral Pain Scale responses to endotracheal suctioning and pupillary pain index scores were positively correlated at T1 and T2 (both P < .01). After adjustments for repeated measurements and group of patients, the area under the receiver operating characteristic curve of pupillary pain index to predict Behavioral Pain Scale response to endotracheal suctioning was of 0.862 (95% CI, 0.714-0.954). In the combined set of patients, a pupillary pain index score of ≤4 could predict no nociceptive response to endotracheal suctioning with a sensitivity of 88% (95% CI, 68%-97%) and a specificity of 79% (95% CI, 66%-88%). By contrast with endotracheal suctioning, tetanic stimulation had no effect on intracranial pressure in the brain-injured group.

CONCLUSIONS

These results are a proof of concept. The nociceptive response to endotracheal suctioning could be accurately predicted using the determination of pupillary pain index score in sedated critically ill patients whether they have brain injury or not.

Review of non-invasive intracranial pressure measurement techniques for ophthalmology applications

Assessment and monitoring of intracranial pressure (ICP) are important in the management of traumatic brain injury and other cerebral pathologies. In the eye, ICP elevation and depression both correlate with optic neuropathies, the former because of papilledema and the latter related to glaucoma. While the relationship between ICP elevation and papilledema is well established, the relationship between low ICP and glaucoma is still poorly understood. So far, ICP monitoring is performed invasively, but this entails risks including infection, spurring the study of non-invasive alternatives. We review 11 methods of non-invasive estimation of ICP including correlation to optic nerve sheath diameter, intraocular pressure, ophthalmodynamometry and two-depth transcranial Doppler of the ophthalmic artery. While none of these methods can fully replace invasive techniques, certain measures show great potential for specific applications. Although only used in small studies to date, a MRI based method known as MR-ICP, appears to be the best non-invasive technique for estimating ICP, with two-depth transcranial ultrasound and ophthalmodynamometry showing potential as well.

Impact of Increased Intracranial Pressure on Pupillometry: A Replication Study

In a diverse, multicenter population, to confirm or refute the conclusions that pupillary light reflex changes are associated with increased intracranial pressure.

Use of the Neurological Pupil Index to Predict Postoperative Visual Function After Resection of a Tuberculum Sellae Meningioma: A Case Report

The Neurological Pupil index (NPi) is a standardized method for evaluating pupil reactivity that removes inter-examiner variability. Changes in the NPi can predict clinical deterioration in patients with traumatic brain injury (TBI); however, its use to predict visual impairment after the resection of parasellar meningiomas has not been described. A 71-year-old female underwent a modified expanded bifrontal craniotomy for resection of a 3.1 cm tuberculum sella meningioma that caused compression of the optic chiasm and resulted in left temporal and right superior temporal visual field deficits. Postoperatively, she lost vision in the right eye. Pupillometer measurements demonstrated an asymmetrically low NPi at that time, which improved to normal prior to partial vision recovery. The average NPi in the right pupil was 1.67 during the time of vision loss compared to 3.47 in the left pupil (p=1.7x10^-10). Statistical analysis was performed with the Student’s t-test and the significance level was set at p-value < 0.01. Resection of parasellar meningiomas is challenging because of the proximity of the optic apparatus. We report a case of unilateral vision loss after resection of a tuberculum sella meningioma in which the impaired eye’s NPi value correlated closely with visual function. NPi values that decrease below 3 predict spikes in intracranial pressure in TBI patients; similarly, increases in the NPi value above 2.5-3 predict improvement in vision in the case reported here. By monitoring the proximal portion of the oculomotor reflex, the NPi can be a marker of visual impairment after surgery.

Quantitative Pupillometry in the Intensive Care Unit

Quantitative pupillometry provides a noninvasive and objective assessment within the neurological examination. This review details the physiology of the pupillary light response, the clinical significance of changes in pupillary reactivity, and the variables that compose the Neurological Pupil index or NPi are discussed. This article reviews the most recent applications and advances in quantitative pupillometry for noninvasive intracranial pressure monitoring, postcardiac arrest prognostication, and subarachnoid hemorrhage. Also discussed are the limitations and confounders of quantitative pupillometry in the modern neurological intensive care unit.

Time effect for in-situ dry needling on the autonomic nervous system, a pilot study

Study design: Pilot study.Background: Dry needling has been an emerging treatment option for physical therapists over the last decade. Despite the fact that studies have demonstrated the overall benefit of dry needling, there is no clear understanding how long needles should be left in place (situ). This pilot study investigated the effects of needles remaining in situ based on autonomic responses over time.Methods: A convenience sample of 21 subjects were recruited for this study. Automated pupillometry was utilized to obtain a direct measure of autonomic nervous system activity. Directly following a baseline measurement, 8 type J Seirin Acupuncture needles were inserted paravertebral at the C7-T3 segments. A total of 8 post-needling 60 seconds pupil measurements were taken at 3 minutes intervals for 24 minutes post needling.Outcomes: A statistical significant difference in mean pupil diameter was found following the needle intervention (p < .01), which implies an increased sympathetic activity. This subject sample had a statistically significantly larger mean pupil diameter immediately after the needling, which lasted until measure point 7, at 18 minutes (P < .05). At measure point 8 there was no longer a statistical significant difference compared to the premeasurement measure.Discussion: The results of this study provide evidence that dry needling results in a significant increased activity of the sympathetic nervous system for up to 18 minutes. Between 18 and 21 minutes autonomic activity returned to a non-significant difference compared to baseline. The results of this study could assist clinicians in clinical decision making to determine needle placement time.

Intracranial pressure monitoring: Gold standard and recent innovations

Intracranial pressure monitoring (ICP) is based on the doctrine proposed by Monroe and Kellie centuries ago. With the advancement of technology and science, various invasive and non-invasive modalities of monitoring ICP continue to be developed. An ideal monitor to track ICP should be easy to use, accurate, reliable, reproducible, inexpensive and should not be associated with infection or haemorrhagic complications. Although the transducers connected to the extra ventricular drainage continue to be Gold Standard, its association with the likelihood of infection and haemorrhage have led to the search for alternate non-invasive methods of monitoring ICP. While Camino transducers, Strain gauge micro transducer based ICP monitoring devices and the Spiegelberg ICP monitor are the emerging technology in invasive ICP monitoring, optic nerve sheath diameter measurement, venous opthalmodynamometry, tympanic membrane displacement, tissue resonance analysis, tonometry, acoustoelasticity, distortion-product oto-acoustic emissions, trans cranial doppler, electro encephalogram, near infra-red spectroscopy, pupillometry, anterior fontanelle pressure monitoring, skull elasticity, jugular bulb monitoring, visual evoked response and radiological based assessment of ICP are the non-invasive methods which are assessed against the gold standard.

Quantitative pupillometry for the monitoring of intracranial hypertension in patients with severe traumatic brain injury

Background

Elevated intracranial pressure (ICP) is frequent after traumatic brain injury (TBI) and may cause abnormal pupillary reactivity, which in turn is associated with a worse prognosis. Using automated infrared pupillometry, we examined the relationship between the Neurological Pupil index (NPi) and invasive ICP in patients with severe TBI.

Methods

This was an observational cohort of consecutive subjects with severe TBI (Glasgow Coma Scale [GCS] < 9 with abnormal lesions on head CT) who underwent parenchymal ICP monitoring and repeated NPi assessment with the NPi-200® pupillometer. We examined NPi trends over time (four consecutive measurements over intervals of 6 h) prior to sustained elevated ICP > 20 mmHg. We further analyzed the relationship of cumulative abnormal NPi burden (%NPi values < 3 during total ICP monitoring time) with intracranial hypertension (ICHT)—categorized as refractory (ICHT-r; requiring surgical decompression) vs. non-refractory (ICHT-nr; responsive to medical therapy)—and with the 6-month Glasgow Outcome Score (GOS).

Results

A total of 54 patients were studied (mean age 54 ± 21 years, 74% with focal injuries on CT), of whom 32 (59%) had ICHT. Among subjects with ICHT, episodes of sustained elevated ICP (n = 43, 172 matched ICP-NPi samples; baseline ICP [T_− 6 h] 14 ± 5 mmHg vs. ICPmax [T_0 h] 30 ± 9 mmHg) were associated with a concomitant decrease of the NPi (baseline 4.2 ± 0.5 vs. 2.8 ± 1.6, p < 0.0001 ANOVA for repeated measures). Abnormal NPi values were more frequent in patients with ICHT-r (n = 17; 38 [3–96]% of monitored time vs. 1 [0–9]% in patients with ICHT-nr [n = 15] and 0.5 [0–10]% in those without ICHT [n = 22]; p = 0.007) and were associated with an unfavorable 6-month outcome (15 [1–80]% in GOS 1–3 vs. 0 [0–7]% in GOS 4–5 patients; p = 0.002).

Conclusions

In a selected cohort of severe TBI patients with abnormal head CT lesions and predominantly focal cerebral injury, elevated ICP episodes correlated with a concomitant decrease of NPi. Sustained abnormal NPi was in turn associated with a more complicated ICP course and worse outcome.

Comparison of full-endoscopic and minimally invasive decompression for lumbar spinal stenosis in the setting of degenerative scoliosis and spondylolisthesis

OBJECTIVE

The management of lumbar spinal stenosis (LSS) with concurrent scoliosis and/or spondylolisthesis remains controversial. Full-endoscopic unilateral laminotomy for bilateral decompression (ULBD) facilitates neural decompression while preserving stabilizing osseoligamentous structures and may be uniquely suited for the treatment of LSS with concurrent mild to moderate degenerative deformity. The safety and efficacy of full-endoscopic versus minimally invasive surgery (MIS) ULBD in this patient population is studied here for the first time.

METHODS

A retrospective analysis of prospectively collected data was conducted on 45 consecutive LSS patients with concurrent scoliosis (≥ 10° coronal Cobb angle) and/or spondylolisthesis (≥ 3 mm). Patient demographics, operative details, complications, and imaging characteristics were reviewed. Outcomes were quantified using back and leg visual analog scale (VAS) scores and the Oswestry Disability Index (ODI) at 2 weeks, 3 months, and 1 year.

RESULTS

A total of 26 patients underwent full-endoscopic and 19 underwent MIS-ULBD with an average follow-up period of 12 months. The endoscopic cohort experienced a significantly shorter hospital length of stay (p = 0.014) and fewer adverse events (p = 0.010). Both cohorts experienced significant improvements in VAS and ODI scores at all time points (p < 0.001), but the endoscopic cohort demonstrated significantly better early ODI scores (p = 0.024).

CONCLUSIONS

Endoscopic and MIS-ULBD result in similar functional outcomes for LSS with mild to moderate deformity, while the endoscopic approach demonstrates a favorable rate of complications. Further studies are required to better delineate the characteristics of spinal deformities amenable to this approach and the durability of functional results.

Comparison of clinical outcomes following minimally invasive or lumbar endoscopic unilateral laminotomy for bilateral decompression

OBJECTIVE

Minimally invasive lumbar unilateral tubular laminotomy for bilateral decompression has gradually gained acceptance as a less destabilizing but efficacious and safe alternative to traditional open decompression techniques. The authors have further advanced the principles of minimally invasive surgery (MIS) by utilizing working-channel endoscope-based techniques. Full-endoscopic technique allows for high-resolution off-axis visualization of neural structures within the lateral recess, thereby minimizing the need for facet joint resection. The relative efficacy and safety of MIS and full-endoscopic techniques have not been directly compared.

METHODS

A retrospective analysis of 95 consecutive patients undergoing either MIS (n = 45) or endoscopic (n = 50) unilateral laminotomies for bilateral decompression in cases of lumbar spinal stenosis was performed. Patient demographics, operative details, clinical outcomes, and complications were reviewed.

RESULTS

The patient cohort consisted of 41 female and 54 male patients whose average age was 62 years. Half of the patients had single-level, one-third had 2-level, and the remaining patients had 3- or 4-level procedures. The surgical time for endoscopic technique was significantly longer per level compared to MIS (161.8 ± 6.8 minutes vs 99.3 ± 4.6 minutes; p < 0.001). Hospital stay for MIS patients was on average 2.4 ± 0.5 days compared to 0.7 ± 0.1 days for endoscopic patients (p = 0.001). At the 1-year follow-up, endoscopic patients had a significantly lower visual analog scale score for leg pain than MIS patients (1.3 ± 0.3 vs 3.0 ± 0.5; p < 0.01). Moreover, the back pain disability index score was significantly lower in the endoscopic cohort than in the MIS cohort (20.7 ± 3.4 vs 35.9 ± 4.1; p < 0.01). Two patients in the MIS group (epidural hematoma) and one patient in the endoscopic group (disc herniation) required a return to the operating room acutely after surgery (< 14 days).

CONCLUSIONS

Lumbar endoscopic unilateral laminotomy for bilateral decompression is a safe and effective surgical procedure with favorable complication profile and patient outcomes.

Automated Pupillometry and Detection of Clinical Transtentorial Brain Herniation: A Case Series

Introduction

Transtentorial herniation (TTH) is a life-threatening neurologic condition that typically results from expansion of supratentorial mass lesions. A change in bedside pupillary examination is central to the clinical diagnosis of TTH. Materials and.

Methods

To quantify the changes in the pupillary examination that precede and accompany TTH and its treatment, we evaluated 12 episodes of herniation in three patients with supratentorial mass lesions using automated pupillometry (NeurOptics, Inc., Irvine, CA). Herniation was defined clinically by the onset of fixed and dilated pupils in association with decreased levels of consciousness. Automated pupillometry was measured simultaneously with the bedside clinical examination, but the clinical team was blinded to these results and could not act on the data. Data from the pupillometer were downloaded 1-2 times per week onto a secured laptop, and data processing was facilitated by the use of Mathematica 8.0.

Results

Neurologic Pupil Index measurements, values generated by the pupillometer based on an algorithm that incorporates pupillary size and reactivity in a normal population, were found to be abnormal before 73% of TTHs. This abnormality occurred at a median of 7.4 h before TTH. All episodes of TTH were reversed after clinical intervention at a median of 43 min after the event. The value did not fall to 0 in 42% of clinical herniations, but it did decrease to very abnormal values of 0.5-0.8.

Conclusions

The potential of automated pupillometry to guide the management of severely injured neurologic patients is intriguing and warrants further study in the critical care unit and beyond. The utility of a portable device in the combat setting may allow for triage of patients with severe neurologic injury.

The relationship between seizure in electroconvulsive therapy and pupillary response using an automated pupilometer

OBJECTIVES

Seizure duration and morphology, postictal suppression, and sympathetic nervous system activation are all recommended as assessments of adequate seizure in electroconvulsive therapy (ECT). However, blood pressure and heart rate are not typically assessed as part of sympathetic nervous system activation because of the administration of anesthetic or cardiovascular agents during ECT. Although the pupils are known to reflect to the activity of autonomic nervous system and the degree of brain damage, previous studies have not examined the relationship between seizure of electroconvulsive therapy and pupillary response.

METHODS

We conducted 98 sessions of ECT with 13 patients, divided into two groups according to seizure quality: (1) adequate or (2) inadequate. Pupillary light reflex [% constriction = (maximum resting pupil size {MAX} - minimum pupil size after light stimulation)/MAX × 100] was measured using a portable infrared quantitative pupilometer before anesthesia induction and immediately after electrical stimulation.

RESULTS

The number regarded as adequate was 67 times and as inadequate was 31 times. Maximum pupil size at the control and immediately after electrical stimulation was similar between the adequate and inadequate groups. Pupillary light reflex was similar at the control between both groups, but significantly smaller immediately after stimulation in the adequate group (2.5 ± 3.6%) compared with the inadequate group (10.6 ± 11.5%). Receiver operating characteristic curve analysis revealed that pupillary light reflex (> 5.5%) predicted adequate seizure.

CONCLUSIONS

The current findings suggest that pupillary constriction immediately after ECT could provide a helpful method for assessing the efficacy of ECT.

Multimodality Monitoring in Neurocritical Care: Decision-Making Utilizing Direct And Indirect Surrogate Markers

Substantial progress has been made to create innovative technology that can monitor the different physiological characteristics that precede the onset of secondary brain injury, with the ultimate goal of intervening prior to the onset of irreversible neurological damage. One of the goals of neurocritical care is to recognize and preemptively manage secondary neurological injury by analyzing physiologic markers of ischemia and brain injury prior to the development of irreversible damage. This is helpful in a multitude of neurological conditions, whereby secondary neurological injury could present including but not limited to traumatic intracranial hemorrhage and, specifically, subarachnoid hemorrhage, which has the potential of progressing to delayed cerebral ischemia and monitoring postneurosurgical interventions. In this study, we examine the utilization of direct and indirect surrogate physiologic markers of ongoing neurologic injury, including intracranial pressure, cerebral blood flow, and brain metabolism.

Understanding the Relationship Between the Neurologic Pupil Index and Constriction Velocity Values

The pupillary light reflex (PLR) describes the response when light hits the retina and sends a signal (cranial nerve II) to the Edinger-Westphal Nucleus which via cranial nerve III results in pupillary constriction. The Neurological Pupil index^TM (NPi) and pupil constriction velocity (CV) are two distinct variables that can be observed and measured using a pupillometer. We examine NPi and CV in 27,462 pupil readings (1,617 subjects). NPi values <3.0 and a CV < 0.8 mm/sec were considered abnormal. Regression was used to clarify the effect of pupil size and repeated measures. An odds ratio of abnormal CV given normal NPi (and vice versa) was computed using the glimmixed (SAS) regression. Of 27,462 readings, 49.2% revealed bilaterally normal NPi wtih brisk CV, and 10.8% revealed bilaterally abnormal NPi and slow CV; 9.1% with unilaterally normal NPi and brisk CV where the opposite pupil had an abnormal NPi and slow CV. The remaining 30.9% revealed that one or both PLR had either a normal NPi with slow CV, or abnormal NPi with brisk CV. Brisk CV does not rule out an abnormal PLR; slow CV does not rule in abnormal PLR. Practitioners should consider these implications when interpreting pupillometry readings.

Eyeing up the Future of the Pupillary Light Reflex in Neurodiagnostics

The pupillary light reflex (PLR) describes the constriction and subsequent dilation of the pupil in response to light as a result of the antagonistic actions of the iris sphincter and dilator muscles. Since these muscles are innervated by the parasympathetic and sympathetic nervous systems, respectively, different parameters of the PLR can be used as indicators for either sympathetic or parasympathetic modulation. Thus, the PLR provides an important metric of autonomic nervous system function that has been exploited for a wide range of clinical applications. Measurement of the PLR using dynamic pupillometry is now an established quantitative, non-invasive tool in assessment of traumatic head injuries. This review examines the more recent application of dynamic pupillometry as a diagnostic tool for a wide range of clinical conditions, varying from neurodegenerative disease to exposure to toxic chemicals, as well as its potential in the non-invasive diagnosis of infectious disease.

Noninvasive Intracranial Pressure Monitoring for Severe Traumatic Brain Injury in Children: A Concise Update on Current Methods

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of pediatric morbidity and mortality worldwide and intracranial pressure (ICP) monitoring plays a crucial role in its management. Based on existing literature, we review the current practicing noninvasive ICP monitoring devices and their accuracy in predicting increased ICP in pediatric TBI.

METHODS

A thorough literature search was conducted on PubMed, Medline, and the Cochrane database, articles were selected systematically and reviewed completely, and relevant data were summarized and discussed.

RESULTS

A total of 27 articles pertaining to pediatric TBI were included and reviewed. We found various modalities of noninvasive ICP monitoring devices used over the last few years. The noninvasive modalities so far attempted in pediatric TBI and so reviewed here are transcranial Doppler, optic nerve sheath diameter, otoacoustic emission, near-infrared spectroscopy, contrast-enhanced ultrasonography, and quantitative pupillometry.

CONCLUSIONS

Invasive monitoring methods are the current gold standard for monitoring ICP; however, complications caused by their invasive nature are of concern. Of all the noninvasive methods based on the literature, we found transcranial Doppler and optic nerve sheath diameter assessment to be the best tools to monitor ICP in pediatric TBI. The promising results and developments of noninvasive ICP monitoring modalities with its ideal features of high sensitivity, diagnostic accuracy, and simple acquisition technique may make it the future of neurointensive monitoring in pediatric TBI.

Differences in pupillary light reflex between optic neuritis and ischemic optic neuropathy

Objectives

To determine the differences in pupillary light reflex (PLR) between the acute and chronic phases of optic neuritis (ON) and nonarteritic anterior ischemic optic neuropathy (NAION).

Methods

The study included 30 patients with ON and 22 patients with NAION whose PLR were measured by a dynamic pupillometer (PLR-200; NeurOptics Inc., Irvine, USA). Age-matched controls included 58 healthy individuals with normal vision and optic nerve function. Pupil diameters, latency, constriction ratio, constriction velocity and dilation velocity were noted. The differences in PLR measurements were compared among the acute and chronic phases of ON and NAION, and in age-matched controls. Regression analysis determined factors associated with PLR measurements, including visual acuity, color vision defect, visual field defects and retinal nerve fiber layer thickness measurements on optical coherence tomography.

Results

Pupillary constriction velocity, constriction ratio and latency were all significantly decreased in the acute phase of ON and NAION. ON showed significantly delayed constriction latency compared to NAION (P = 0.047). Pupillary constriction velocity, constriction ratio and latency were recovered in the chronic phase of ON (P = 0.038, 0.018, and 0.045), however, these parameters were not recovered in NAION (P = 0.693, 0.173 and 0.994).

Conclusions

Pupillary constriction velocity, constriction ratio, and latency were significantly decreased in the acute phase of ON and NAION compared to normal controls. ON showed delayed constriction latency compared to NAION. Decreased PLR were recovered in the chronic phase of ON, but not in NAION.

Noninvasive Neuromonitoring: Current Utility in Subarachnoid Hemorrhage, Traumatic Brain Injury, and Stroke

Noninvasive neuromonitoring is increasingly being used to monitor the course of primary brain injury and limit secondary brain damage of patients in the neurocritical care unit. Proposed advantages over invasive neuromonitoring methods include a lower risk of infection and bleeding, no need for surgical installation, mobility and portability of some devices, and safety. The question, however, is whether noninvasive neuromonitoring is practical and trustworthy enough already. We searched the recent literature and reviewed English-language studies on noninvasive neuromonitoring in subarachnoid hemorrhage, traumatic brain injury, and ischemic and hemorrhagic stroke between the years 2010 and 2015. We found 88 studies that were eligible for review including the methods transcranial ultrasound, electroencephalography, evoked potentials, near-infrared spectroscopy, bispectral index, and pupillometry. Noninvasive neuromonitoring cannot yet completely replace invasive methods in most situations, but has great potential being complementarily integrated into multimodality monitoring, for guiding management, and for limiting the use of invasive devices and in-hospital transports for imaging.

The use and uptake of pupillometers in the Intensive Care Unit

BACKGROUND

Traumatic brain injury (TBI) is a significant public health issue. Assessing pupil reactivity is a crucial aspect of its management and the pupillometer has been shown to be a more objective tool compared to the standard penlight. Its use, however, is not widespread.

OBJECTIVE

To investigate the paucity in uptake, we examined the frequency of use of pupillometers (NeurOptics^®NPi-100™) amongst Intensive Care Unit (ICU) doctors and nurses, evaluated its user-friendliness and explored barriers to its use.

DESIGN

An online cross-sectional survey.

METHODS

Surveys were distributed five months after the introduction of pupillometers (in May 2015) to ICU doctors and nurses working in a quaternary referral centre providing state services for trauma. The survey included sections on: questions on demographics and experience, methods of conventional pupillary assessment in patients with TBI, experience of using the pupillometer, and questions on barriers to its use. Responses were collated as discrete variables and summarised using counts and proportions. Comparisons among proportions were undertaken using the chi-squared test and reported with 95% confidence intervals.

RESULTS

A total of 79 responses were recorded, predominantly 94.9% (n=75) from nursing staff. A total of 50 (63.3%) responders were using the pupillometers, with a mean frequency-of-use rating of 4.67 out of 10 and a mean user-friendliness rating of 6.28 out of 10. There was no association between frequency of use and user-friendliness (p=0.36). The main identified barriers to its use included a lack of education with regards to its use, a perceived lack of clinical significance, a lack of standardisation of documenting findings, and difficulties with access to disposable patient shields (Smartguards).

CONCLUSIONS

There was good adoption of the technology in the early phases of ICU implementation with user-friendliness rated favourably. In this paper we identify barriers to use and discuss possible solutions to increase clinical utility.

Noninvasive monitoring intracranial pressure - A review of available modalities

Background:

Intracranial pressure (ICP) monitoring is important in many neurosurgical and neurological patients. The gold standard for monitoring ICP, however, is via an invasive procedure resulting in the placement of an intraventricular catheter, which is associated with many risks. Several noninvasive ICP monitoring techniques have been examined with the hope to replace the invasive techniques. The goal of this paper is to provide an overview of all modalities that have been used for noninvasive ICP monitoring to date.

Methods:

A thorough literature search was conducted on PubMed, selected articles were reviewed in completion, and pertinent data was included in the review.

Results:

A total of 94 publications were reviewed, and we found that over the past few decades clinicians have attempted to use a number of modalities to monitor ICP noninvasively.

Conclusion:

Although the intraventricular catheter remains the gold standard for monitoring ICP, several noninvasive modalities that can be used in settings when invasive monitoring is not possible are also available. In our opinion, measurement of optic nerve sheath diameter and pupillometry are the two modalities which may prove to be valid options for centers not performing invasive ICP monitoring.

Controversies in the Management of Traumatic Brain Injury

Traumatic brain injury (TBI) is a physical insult (a bump, jolt, or blow) to the brain that results in temporary or permanent impairment of normal brain function. TBI describes a heterogeneous group of disorders. The resulting secondary injury, namely brain swelling and its sequelae, is the reason why patients with these vastly different initial insults are homogenously treated. Much of the evidence for the management of TBI is poor or conflicting, and thus definitive guidelines are largely unavailable for clinicians at this time. A substantial portion of this article focuses on discussing the controversies in the management of TBI.

Non-invasive intracranial pressure assessment

Assessing intracranial pressure (ICP) remains a cornerstone in neurosurgical care. Invasive techniques for monitoring ICP remain the gold standard. The need for a reliable, safe and reproducible technique to non-invasively assess ICP in the context of early screening and in the neurocritical care environment is obvious. Numerous techniques have been described with several novel advances. While none of the currently available techniques appear independently accurate enough to quantify raised ICP, there is some promising work being undertaken.