Correlation between computed tomography and intracranial pressure monitoring in acute head trauma patients

Midline Shift is Unrelated to Subjective Pupillary Reactivity Assessment on Admission in Moderate and Severe Traumatic Brain Injury

Background

This study aims to determine the relationship between pupillary reactivity, midline shift and basal cistern effacement on brain computed tomography (CT) in moderate-to-severe traumatic brain injury (TBI). All are important diagnostic and prognostic measures, but their relationship is unclear.

Methods

A total of 204 patients with moderate-to-severe TBI, documented pupillary reactivity, and archived neuroimaging were included. Extent of midline shift and basal cistern effacement were extracted from admission brain CT. Mean midline shift was calculated for each ordinal category of pupillary reactivity and basal cistern effacement. Sequential Chi-square analysis was used to calculate a threshold midline shift for pupillary abnormalities and basal cistern effacement. Univariable and multiple logistic regression analyses were performed.

Results

Pupils were bilaterally reactive in 163 patients, unilaterally reactive in 24, and bilaterally unreactive in 17, with mean midline shift (mm) of 1.96, 3.75, and 2.56, respectively (p = 0.14). Basal cisterns were normal in 118 patients, compressed in 45, and absent in 41, with mean midline shift (mm) of 0.64, 2.97, and 5.93, respectively (p < 0.001). Sequential Chi-square analysis identified a threshold for abnormal pupils at a midline shift of 7–7.25 mm (p = 0.032), compressed basal cisterns at 2 mm (p < 0.001), and completely effaced basal cisterns at 7.5 mm (p < 0.001). Logistic regression revealed no association between midline shift and pupillary reactivity. With effaced basal cisterns, the odds ratio for normal pupils was 0.22 (95% CI 0.08–0.56; p = 0.0016) and for at least one unreactive pupil was 0.061 (95% CI 0.012–0.24; p < 0.001). Basal cistern effacement strongly predicted midline shift (OR 1.27; 95% CI 1.17–1.40; p < 0.001).

Conclusions

Basal cistern effacement alone is associated with pupillary reactivity and is closely associated with midline shift. It may represent a uniquely useful neuroimaging marker to guide intervention in traumatic brain injury.

Diagnosis of elevated intracranial pressure in critically ill adults: systematic review and meta-analysis

OBJECTIVES

To summarise and compare the accuracy of physical examination, computed tomography (CT), sonography of the optic nerve sheath diameter (ONSD), and transcranial Doppler pulsatility index (TCD-PI) for the diagnosis of elevated intracranial pressure (ICP) in critically ill patients.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Six databases, including Medline, EMBASE, and PubMed, from inception to 1 September 2018.

STUDY SELECTION CRITERIA

English language studies investigating accuracy of physical examination, imaging, or non-invasive tests among critically ill patients. The reference standard was ICP of 20 mm Hg or more using invasive ICP monitoring, or intraoperative diagnosis of raised ICP.

DATA EXTRACTION

Two reviewers independently extracted data and assessed study quality using the quality assessment of diagnostic accuracy studies tool. Summary estimates were generated using a hierarchical summary receiver operating characteristic (ROC) model.

RESULTS

40 studies (n=5123) were included. Of physical examination signs, pooled sensitivity and specificity for increased ICP were 28.2% (95% confidence interval 16.0% to 44.8%) and 85.9% (74.9% to 92.5%) for pupillary dilation, respectively; 54.3% (36.6% to 71.0%) and 63.6% (46.5% to 77.8%) for posturing; and 75.8% (62.4% to 85.5%) and 39.9% (26.9% to 54.5%) for Glasgow coma scale of 8 or less. Among CT findings, sensitivity and specificity were 85.9% (58.0% to 96.4%) and 61.0% (29.1% to 85.6%) for compression of basal cisterns, respectively; 80.9% (64.3% to 90.9%) and 42.7% (24.0% to 63.7%) for any midline shift; and 20.7% (13.0% to 31.3%) and 89.2% (77.5% to 95.2%) for midline shift of at least 10 mm. The pooled area under the ROC (AUROC) curve for ONSD sonography was 0.94 (0.91 to 0.96). Patient level data from studies using TCD-PI showed poor performance for detecting raised ICP (AUROC for individual studies ranging from 0.55 to 0.72).

CONCLUSIONS

Absence of any one physical examination feature is not sufficient to rule out elevated ICP. Substantial midline shift could suggest elevated ICP, but the absence of shift cannot rule it out. ONSD sonography might have use, but further studies are needed. Suspicion of elevated ICP could necessitate treatment and transfer, regardless of individual non-invasive tests.

REGISTRATION

PROSPERO CRD42018105642.

Management of severe traumatic brain injury (first 24hours)

The latest French Guidelines for the management in the first 24hours of patients with severe traumatic brain injury (TBI) were published in 1998. Due to recent changes (intracerebral monitoring, cerebral perfusion pressure management, treatment of raised intracranial pressure), an update was required. Our objective has been to specify the significant developments since 1998. These guidelines were conducted by a group of experts for the French Society of Anesthesia and Intensive Care Medicine (Société francaise d'anesthésie et de réanimation [SFAR]) in partnership with the Association de neuro-anesthésie-réanimation de langue française (ANARLF), The French Society of Emergency Medicine (Société française de médecine d'urgence (SFMU), the Société française de neurochirurgie (SFN), the Groupe francophone de réanimation et d'urgences pédiatriques (GFRUP) and the Association des anesthésistes-réanimateurs pédiatriques d'expression française (ADARPEF). The method used to elaborate these guidelines was the Grade^® method. After two Delphi rounds, 32 recommendations were formally developed by the experts focusing on the evaluation the initial severity of traumatic brain injury, the modalities of prehospital management, imaging strategies, indications for neurosurgical interventions, sedation and analgesia, indications and modalities of cerebral monitoring, medical management of raised intracranial pressure, management of multiple trauma with severe traumatic brain injury, detection and prevention of post-traumatic epilepsia, biological homeostasis (osmolarity, glycaemia, adrenal axis) and paediatric specificities.

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.

Non-invasive assessment of intracranial pressure

Monitoring of intracranial pressure (ICP) is invaluable in the management of neurosurgical and neurological critically ill patients. Invasive measurement of ventricular or parenchymal pressure is considered the gold standard for accurate measurement of ICP but is not always possible due to certain risks. Therefore, the availability of accurate methods to non-invasively estimate ICP has the potential to improve the management of these vulnerable patients. This review provides a comparative description of different methods for non-invasive ICP measurement. Current methods are based on changes associated with increased ICP, both morphological (assessed with magnetic resonance, computed tomography, ultrasound, and fundoscopy) and physiological (assessed with transcranial and ophthalmic Doppler, tympanometry, near-infrared spectroscopy, electroencephalography, visual-evoked potentials, and otoacoustic emissions assessment). At present, none of the non-invasive techniques alone seem suitable as a substitute for invasive monitoring. However, following the present analysis and considerations upon each technique, we propose a possible flowchart based on the combination of non-invasive techniques including those characterizing morphologic changes (e.g., repetitive US measurements of ONSD) and those characterizing physiological changes (e.g., continuous TCD). Such an integrated approach, which still needs to be validated in clinical practice, could aid in deciding whether to place an invasive monitor, or how to titrate therapy when invasive ICP measurement is contraindicated or unavailable.

Non-invasive methods of estimating intracranial pressure

Non-invasive measurement of intracranial pressure can be invaluable in the management of critically ill patients. We performed a comprehensive review of the literature to evaluate the different methods of measuring intracranial pressure. Several methods have been employed to estimate intracranial pressure, including computed tomography, magnetic resonance imaging, transcranial Doppler sonography, near-infrared spectroscopy, and visual-evoked potentials. In addition, multiple techniques of measuring the optic nerve and the optic nerve sheath diameter have been studied. Ultrasound measurements of the optic nerve sheath diameter and Doppler flow are especially promising and may be useful in selected settings.

The relationship between basal cisterns on CT and time-linked intracranial pressure in paediatric head injury

PURPOSE

Although intracranial pressure (ICP) monitoring is a cornerstone of care for severe traumatic brain injury (TBI), the indications for ICP monitoring in children are unclear. Often, decisions are based on head computed tomography (CT) scan characteristics. Arguably, the patency of the basal cisterns is the most commonly used of these signs. Although raised ICP is more likely with obliterated basal cisterns, the implications of open cisterns are less clear. We examined the association between the status of perimesencephalic cisterns and time-linked ICP values in paediatric severe TBI.

METHODS

ICP data linked to individual head CT scans were reviewed. Basal cisterns were classified as open or closed by blinded reviewers. For the initial CT scan, we examined ICP values for the first 6 h after monitor insertion. For follow-up scans, we examined ICP values 3 h before and after scanning. Mean ICP and any episode of ICP ≥ 20 mmHg during this period were recorded.

RESULTS

Data from 104 patients were examined. Basal cisterns were patent in 51.72% of scans, effaced in 34.48% and obliterated in 13.79%. Even when cisterns were open, more than 40% of scans had at least one episode of ICP ≥ 20 mmHg, and 14% of scans had a mean ICP ≥ 20 mmHg. The specificity of open cisterns in predicting ICP < 20 mmHg was poor (57.9%). Age-related data were worse.

CONCLUSION

Children with severe TBI frequently may have open basal cisterns on head CT despite increased ICP. Open cisterns should not discourage ICP monitoring.

[Post-traumatic temporal lobe lesions: surgical decision making based on CT scan findings]

BACKGROUND

The indication for surgical treatment of post-traumatic parenchymal lesions in the temporal lobe remains controversial.

OBJECTIVE

We reviewed the tomographic parameters that might be useful in making surgical decisions.

METHOD

The tomographic findings of 69 patients were analyzed in a retrospective manner considering: 1) the effects of the lesion (classified into 4 variables: midline shift, status of the cisterns, status of the ventricles, and status of the peripheral sulci); and 2) the characteristics of the lesion: anterior, posterior or anteroposterior location (as defined by a coronal plane tangent to the cerebral peduncles) and its mediolateral diameter.

RESULTS

When none or only one of the aforementioned variables was found to be altered, conservative treatment was instituted (22 out of 38 lesions). In two cases, all four variables were altered, and surgery was performed in both. Anterior, anteroposterior and posterior lesions measuring 21, 23 and 28 mm in diameter, respectively, had a 50% chance of surgical removal.

CONCLUSION

Amongst the patients who underwent surgical intervention, the more anterior the location of the temporal lobe lesion, the smaller the diameter.

Initial head computed tomographic scan characteristics have a linear relationship with initial intracranial pressure after trauma

BACKGROUND

Despite current recommendations by the Brain Trauma Foundation regarding the placement of intracranial pressure (ICP) monitoring devices, advances in computed tomographic (CT) scan technology have led to the suggestion that increased ICP may be predicted by findings on admission head CT scan and that patients without such findings do not require such monitoring. A linear relationship exists between characteristics of admission head CT scan and initial ICP level, allowing for selective placement of ICP monitoring devices.

METHODS

From 1997 to 2001, a retrospective review of patients admitted with a Glasgow Coma Scale (GCS) score < 8 and head CT scan who underwent ventriculostomy placement at our institution, was conducted. Patients undergoing craniotomy with evacuation of mass lesions before ventriculostomy placement were excluded. Age, sex, mechanism of injury, anoxia, osmotic treatment, presence of drugs/alcohol, initial mean arterial pressure, initial GCS score, and initial ICP were recorded. Initial head CT scans were reviewed independently by two neuroradiologists who were blinded to ICP measurements, neurosurgical treatment, patient outcome, and each other's interpretation. Initial CT scans were evaluated and scored on a 1 (normal) to 3 (abnormal) scale with respect to ventricle size, basilar cistern size, sulci size, degree of transfalcine herniation, and gray/white matter differentiation. Initial ICP readings and CT scan findings were compared to determine whether a significant linear relationship existed between the above CT scan findings and ICPs. Logistic and univariate linear regression were used to compare averaged radiologist score versus dichotomized ICP at baseline.

RESULTS

Initial head CT scan characteristics show a linear relationship to baseline ICPs. These findings are associative, but are not uniformly predictive.

CONCLUSION

Therefore, the current Brain Trauma Foundation recommendation of ICP monitoring in those patients presenting with a GCS score < 8 with an abnormal CT scan or a normal CT scan with age > 40 years, systolic blood pressure < 90 mm Hg, or exhibiting posturing should be followed.

The efficacy of routine head computed tomography (CT scan) prior to lumbar puncture in the emergency department

The efficacy of using unenhanced head computed tomography (CT scans) as a routine screening procedure prior to lumbar puncture in the emergency department is studied retrospectively by comparing opening pressure during lumbar puncture to CT scan diagnosis in 42 patients. No correlation was found between CT scan findings and opening pressure.

Role of intracranial pressure monitoring in severely head-injured patients without signs of intracranial hypertension on initial computerized tomography

Previous studies have suggested that only a small proportion (< 15%) of comatose head-injured patients whose initial computerized tomography (CT) scan was normal or did not show a mass lesion, midline shift, or abnormal basal cisterns develop intracranial hypertension. The aim of the present study was to re-examine this finding against a background of more intensive monitoring and data acquisition. Eight severely head-injured patients with a Glasgow Coma Scale score of 8 or less, whose admission CT scan did not show a mass lesion, midline shift, or effaced basal cisterns, underwent minute-to-minute recordings of arterial blood pressure, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) derived from blood pressure minus ICP. Intracranial hypertension (ICP > or = 20 mm Hg lasting longer than 5 minutes) was recorded in seven of the eight patients; in five cases the rise was pronounced in terms of both magnitude (ICP > or = 30 mm Hg) and duration. Reduced CPP (< or = 60 mm Hg lasting longer than 5 minutes) was recorded in five patients. Severely head-injured (comatose) patients whose initial CT scan is normal or does not show a mass lesion, midline shift, or abnormal cisterns nevertheless remain at substantial risk of developing significant secondary cerebral insults due to elevated ICP and reduced CPP. The authors recommend continuous ICP and blood pressure monitoring with derivation of CPP in all comatose head-injured patients.

Initial CT findings in 753 patients with severe head injury. A report from the NIH Traumatic Coma Data Bank

In this prospective multicenter study, the authors have examined data derived from the initial computerized tomography (CT) scans of 753 patients with severe head injury. When the CT findings were related to abnormal intracranial pressure and to death, the most important characteristics of the scans were: midline shift: compression or obliteration of the mesencephalic cisterns: and the presence of subarachnoid blood. Diffuse hemispheric swelling was also found to be associated with an early episode of either hypoxia or hypotension.

Estimation of intracranial pressure using computed tomography scan findings in patients with severe head injury

The relationship between initial intracranial pressure and the findings of the first computed tomography scan on admission was assessed in 100 consecutive moderate-to-severe head injury patients using a method of multiple regression analysis. Intracranial pressure was measured through a slender subarachnoid catheter with a transducer. Thirty-nine checkpoints of computed tomography findings, including a shift of midline structure, the status of ventricles or cisterns, and the amount of subarachnoid hemorrhage, were investigated. The results were as follows: (1) The computed tomography findings that contributed to estimating intracranial pressure were the appearance of cisterns, the size of a subdural hematoma (number of slices), ventricular size, status of subarachnoid hemorrhage, status of cerebral contusion, magnitude of midline shift, and ventricular index, in that order. (2) Approximately 80% of predicted cases of intracranial pressure were included within the range of measured intracranial pressure +/- 10 mmHg. When the predicted intracranial pressure was less than 30 mmHg, the discrepancy between both intracranial pressures was small. It is concluded that an equation using several computed tomography findings gives a reasonably accurate intracranial pressure for the initial stage of severe head injury.

Contraindications to lumbar puncture as defined by computed cranial tomography

Papilloedema is not always an adequate predictor of potential complications from lumbar puncture, and many clinicians are using computed tomography (CT) before lumbar puncture in an effort to identify more accurately the "at risk" patient. This paper identifies the following anatomical criteria defined by CT scanning that correlate with unequal pressures between intracranial compartments and predispose a patient to herniation following decompression of the spinal compartment: lateral shift of midline structures, loss of the suprachiasmatic and basilar cisterns, obliteration of the fourth ventricle, or obliteration of the superior cerebellar and quadrigeminal plate cisterns with sparing of the ambient cisterns. These criteria should be considered to be contraindications to lumbar puncture.

Emergency CT head scans in traumatic and atraumatic conditions

Head trauma and suspected subarachnoid hematoma are encountered frequently by the emergency physician. There are few data to indicate which patients need immediate computerized tomography (CT) and what is the role of lumbar puncture in subarachnoid hemorrhage. Reviewed are the classification of head trauma and subarachnoid hemorrhage, indications for immediate CT, persons needing contrast enhancement, and the use of CT in comparison to skull films, digital subtraction angiography, and magnetic resonance.

CT scan in severe diffuse head injury: physiological and clinical correlations

CT scan findings, clinical features and intracranial pressure were studied in patients with severe diffuse head injury. Compression of the 3rd ventricle and basal cisterns closely correlated with an intracranial pressure greater than 20 mmHg, with clinical signs of midbrain dysfunctions and worse prognosis. These CT scan findings can indicate whether intracranial pressure monitoring is appropriate.

Estimation of intracranial pressure by CT scan in closed head trauma

The predictive values of certain features of computerized tomographic (CT) scans in estimating intracranial pressure (ICP) were investigated in 40 patients following closed head injuries. The various features of CT scans selected for study included ventricular compression, the size of the parenchymal mass lesion, midline shift, and an intraventricular clot. All patients with intraventricular clot exhibited severe elevation of pressure. Ventricular compression correlated well with the level of intracranial pressure. Size of the mass was found to be suggestive of pressure elevation but did not reach statistical significance. Midline shift showed no correlation with the intracranial pressure.

Intracranial pressure: to monitor or not to monitor? A review of our experience with severe head injury

✓ The authors have analyzed their experience with intracranial pressure (ICP) monitoring in 207 patients over a 4-year period. Patients with either high-density or low-density lesions on computerized tomography (CT) at admission had a high incidence (53% to 63%) of intracranial hypertension (ICP persistently over 20 mm Hg). In contrast, patients with normal CT scans at admission had a relatively low incidence of ICP elevation (13%). Among these patients, three features were found to be strongly associated with the development of intracranial hypertension: 1) age over 40 years; 2) systolic blood pressure under 90 mm Hg; and 3) motor posturing — unilateral or bilateral. When two or more of these features were noted at admission, the incidence of intracranial hypertension was 60%, as compared to 4% when only one, or none, of these features were present. Thus, the patients at high risk for developing intracranial hypertension after severe head injury are those with abnormal CT scans at admission, and those with normal CT scans who demonstrate two or more of the above-mentioned adverse features. Based on these criteria, only 16% of this series of patients with normal CT scans would have qualified for monitoring.

In addition to the three clinical features noted above, multimodality evoked potential (MEP) studies were also found to be strong predictors of ICP elevation in the normal CT scan group, with a 75% incidence of intracranial hypertension in patients with disseminated deficits. There was no statistically significant correlation between the Glasgow Coma Scale score, eye movements, pupillary reaction, hypoxia, or anemia at admission and subsequent ICP elevation in the group with normal CT scans.

In this series, an intraventricular catheter was used as the sole monitoring device in 91% of the cases. In the remaining 9%, subarachnoid screws were employed, either alone, or upon failure of the ventriculostomy. While no mortality was directly ascribed to the monitoring process, there was a 7.7% complication rate (infection 6.3% + hemorrhage 1.4%). Eighty-five percent of the infections occurred in patients who had been monitored for 5 days or more, while no infections were noted in those monitored for less than 3 days. Used judiciously, this technique can be valuable in the monitoring and treatment of the brain-injured patient.

Hemostasis and computerized tomography in head injury. Their relationship to clinical features

Coagulation studies (plasma fibrinogen, ethanol gelation test, and fibrin-fibrinogen degradation product concentration) and computerized tomography (CT) scan examinations were performed in 55 patients with blunt head injury. The frequency of abnormalities in both coagulation study results and CT scans was higher in patients with severe clinical features and clinical course than in less severely injured patients; in these same patients the coagulation results were abnormal (64%) more frequently than the CT scans (40%). Very high fibrin-fibrinogen degradation product (FDP) concentrations were found to be associated with combined hemorrhagic lesions and mass effect on CT scans, but not with a specific localization of brain-tissue damage. It was concluded that: 1) FDP concentration reflects the amount of brain-tissue damage rather than its location, and 2) in the absence of other possible causes of disseminated intravascular coagulation, coagulation studies may be more sensitive than CT scanning in demonstrating brain contusion.

CT in head trauma: a review

The diagnosis and management of head trauma has changed significantly with the availability of computed tomography. CT not only demonstrates the presence of a mass, but also delineates acute bleed from brain swelling. CT is useful in determining whether the hematoma is intracerebral or extracerebral, as well as its volume, extent, and multiplicity. CT provides the opportunity for noninvasive sequential studies in the management of the patient with severe head trauma. Sequential CT studies have also been useful in understanding the long-term effects of head trauma. CT has eliminated the need for other diagnostic studies in all but the most exceptional situations.

The excessively small ventricle on cranial computed tomography: clinical correlation in 75 patients

Excessively small ventricle (ESV) was demonstrated in 75 (8.3%) of 9,000 patients over 15 years of age examined by cranial computed tomography (CT). The patients had no other CT abnormality except for ESV. Detailed retrospective analysis of clinical records of these 75 patients revealed four major groups of patients: 1) those with seizures (24%); 2) those with headaches (24%); 3) those with acute non-penetrating head trauma (21.5%); and 4) those with benign increased intracranial pressure (8%). The remaining patients (22.5%) had a variety of cerebral derangements.