The role of transcranial Doppler in the management of patients with subarachnoid haemorrhage--a review

Association Between Ionized Calcium Level and Neurological Outcome in Endovascularly Treated Patients with Spontaneous Subarachnoid Hemorrhage: A Retrospective Cohort Study

BACKGROUND

Spontaneous subarachnoid hemorrhage (SSAH) is associated with significant morbidity and mortality. Pathophysiological processes following initial bleeding are complex and not fully understood. In this study, we aimed to determine whether a low level of ionized calcium (Ca⁺⁺), an essential cofactor in the coagulation cascade and other cellular processes, is associated with adverse neurological outcome, development of early hydrocephalus, and symptomatic vasospasm among patients with SSAH.

METHODS

This was a retrospective single-center cohort study of all patients admitted for SSAH between January 1, 2009, and April 31, 2020. The primary outcome was an unfavorable neurological status at discharge, defined as a modified Rankin Scale score greater than or equal to 3. Secondary outcomes were the development of early hydrocephalus and symptomatic vasospasm. Multivariable logistic regression was performed to determine whether Ca⁺⁺ was an independent predictor of these outcomes.

RESULTS

A total of 255 patients were included in the final analysis. Hypocalcemia, older age, admission Glasgow Coma Scale (GCS) score, and admission Hunt-Hess classification scale (H&H) grades IV and V were independently associated with unfavorable neurological outcome, with adjusted odds ratios (ORs) of 1.93 (95% confidence interval [CI] 1.1-3.4; p = 0.02) for each 0.1 mmol L^-1 decrease in the Ca⁺⁺ level, 1.04 (95% CI 1.01-1.08; p = 0.02) for each year increase, 0.82 (95% CI 0.68-0.99; p = 0.04), and 6.29 (95% CI 1.14-34.6; p = 0.03), respectively. Risk factors for the development of hydrocephalus were hypocalcemia and GCS score, with ORs of 1.85 (95% CI 1.26-2.71; p = 0.002) for each 0.1 mmol L^-1 decrease in the Ca⁺⁺ level and 0.83 (95% CI 0.73-0.94; p = 0.005), respectively. Ca⁺⁺ was not associated with symptomatic vasospasm (OR 1.04 [95% CI 0.76-1.41]; p = 0.81). Among patients with admission H&H grade I-III bleeding, hypocalcemia was independently associated with unfavorable neurological outcome at discharge, with an adjusted OR of 1.99 (95% CI 1.03-3.84; p = 0.04) for each 0.1 mmol L^-1 decrease in the Ca⁺⁺ level. Hypocalcemia was also an independent risk factor for the development of early hydrocephalus, with an adjusted OR of 2.95 (95% CI 1.49-5.84; p = 0.002) for each 0.1 mmol L^-1 decrease in the Ca⁺⁺ level. Ca⁺⁺ was not associated with symptomatic vasospasm. No association was found between Ca⁺⁺ and predefined outcomes among patients with admission H&H grade IV and V bleeding.

CONCLUSIONS

Our study shows that hypocalcemia is associated with worse neurological outcome at discharge and development of early hydrocephalus in endovascularly treated patients with SSAH. Potential mechanisms include calcium-induced coagulopathy and higher blood pressure. Trials are needed to assess whether correction of hypocalcemia will lead to improved outcomes.

Transcranial Doppler in the Detection and Management of Arterial Vasospasm after Aneurysmal Subarachnoid Haemorrhage

Delayed cerebral ischaemia (DCI) and cerebral infarction is a much-feared complication of aneurysmal subarachnoid haemorrhage (aSAH). It has been largely attributed to focal hypoperfusion from reversible cerebral arterial narrowing, “vasospasm,” from the effects of prolonged exposure of the arteries to perivascular blood and oxy-haemoglobin. Transcranial Doppler (TCD) provides a non-invasive method for detecting and monitoring vasospasm. We report a 38-year-old lady who developed sudden dizziness and catastrophic generalised headache with neck pain (Pain Score 10/10) while voiding her bowels. She subsequently became drowsy and was brought to hospital. On examination, she was already alert and orientated. Blood pressure was 175/109 mm Hg. Her neurological examination was normal but for severe neck stiffness to passive flexion. Computed tomography of the brain showed extensive SAH. Cerebral angiography revealed a 6 × 3 mm aneurysm along the posteromedial aspect of the supraclinoid left internal carotid artery. She underwent aneurysm coiling that night. She was given intravenous and then oral nimodipine. TCD monitoring of the circle of Willis on day 14 detected very high velocities in the right and left middle cerebral arteries, mean velocity 187 and 141 cm/s, middle cerebral artery/internal carotid artery ratio 6.03 and 4.15, suggestive of severe and moderate vasospasm, respectively. She did not develop any related neurological symptoms or deficits. She was maintained in a euvolemic state and given high volumes of intravenous saline (2.4 L/day). Repeat TCD 7 days later was normal. The intravenous saline was gradually tailed off and she was subsequently discharged. TCD has an important role in the non-invasive detection and monitoring of vasospasm after aSAH.

LPS Pretreatment Provides Neuroprotective Roles in Rats with Subarachnoid Hemorrhage by Downregulating MMP9 and Caspase3 Associated with TLR4 Signaling Activation

Subarachnoid hemorrhage (SAH), as a severe brain disease, has high morbidity and mortality. SAH usually induced neurological dysfunction or death and the treatment is far from satisfaction. Here, we investigated the effect of low dose of LPS pretreatment and underlying molecular mechanism in rat SAH model. Firstly, SAH model was induced by prechiasmal cistern injection method (SAH1) and common carotid artery-prechiasmal cistern shunt method (SAH2), respectively, to select the more suitable SAH model. At 6, 12, 24, 48, and 72 h after SAH, brain injury including neurological dysfunction, blood-brain barrier disruption, brain edema, and cell apoptosis were detected. And the expression of MMP9, HMGB1/TLR4, and caspase3 in cortex were also explored. Then, SB-3CT, an inhibitor of MMP9, was administrated to investigate the exact function of MMP9 in the brain injury at 24 h after SAH. Moreover, low dose of LPS was used to verify whether it had nerve protection after SAH and the mechanism involving in MMP9 and caspase 3 was investigated. Our results showed SAH1 seems to be the most suitable SAH model. In addition, MMP9 activated by HMGB1/TLR4 may promote or aggravate brain injury, while inhibiting MMP9 via SB-3CT exerted a neuroprotective effect. Moreover, LPS improved the neurological dysfunction, reduced Evans blue extravasation and brain edema, and inhibited cell apoptosis of cortex in rats with brain injury induced by SAH. Importantly, LPS pretreatment increased the expression level of TLR4, and decreased the level of MMP9 and caspase3. Therefore, the present study revealed that low dose of LPS pretreatment could provide neuroprotective effects on brain injury caused by SAH via downregulating MMP9 and caspase3 and activating TLR4 signal pathway.

Prediction of Delayed Cerebral Ischemia After Subarachnoid Hemorrhage Using Cerebral Blood Flow Velocities and Cerebral Autoregulation Assessment

BACKGROUND

The risk of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is associated with large cerebral artery vasospasm, but vasospasm is not a strong predictor for DCI. Assessment of cerebral autoregulation with transcranial Doppler (TCD) may improve the prediction of DCI. The aim of this prospective study was to assess the value of TCD-derived variables to be used alone or in combination for prediction of DCI.

METHODS

We included consecutive patients with low-grade aneurysmal SAH within 4 days of aneurysm rupture. Cerebral autoregulation was evaluated using the moving correlation coefficient Mx calculated from spontaneous fluctuations of cerebral blood flow velocities and arterial blood pressure. Transcranial color-coded sonography was performed to assess large artery vasospasm.

RESULTS

Thirty patients (19 women and 11 men; mean age ± SD 44.7 ± 12.1 years) were included. Twenty (66.7%) patients had vasospasm. DCI occurred in six (20%) patients after a median delay of 10 days (range 8-13 days). Cerebral autoregulation was impaired at baseline and at day 7 and then returned to normal at day 14. Neither cerebral autoregulation impairment nor large artery vasospasm alone was associated with DCI. In contrast, the combination of large artery vasospasm with worsening impairment of cerebral autoregulation from baseline to day 7 was significantly correlated to subsequent DCI (p = 0.007).

CONCLUSIONS

Early deterioration of cerebral autoregulation was strongly predictive of DCI in patients with large artery vasospasm after low-grade SAH. Our results suggest that consideration to both cerebral blood flow velocities and cerebral autoregulation may improve the prediction of DCI.

Reduced circulating endothelial progenitor cells in reversible cerebral vasoconstriction syndrome

BACKGROUND

The pathophysiology of reversible cerebral vasoconstriction syndrome (RCVS) remains elusive. Endothelial dysfunction might play a role, but direct evidence is lacking. This study aimed to explore whether patients with RCVS have a reduced level of circulating circulating endothelial progenitor cells (EPCs) to repair the dysfunctional endothelial vasomotor control.

METHODS

We prospectively recruited 24 patients with RCVS within one month of disease onset and 24 healthy age- and sex-matched controls. Flow cytometry was used to quantify the numbers of circulating EPCs, defined as KDR+CD133+, CD34+CD133+, and CD34+KDR+ double-positive mononuclear cells. The Lindegaard index, an index of vasoconstriction, was calculated by measuring the mean flow velocity of middle cerebral arteries and distal extracranial internal carotid arteries via color-coded sonography on the same day as blood drawing. A Lindegaard index of 2 was chosen as the cutoff value for significant vasoconstriction of middle cerebral arteries based on our previous study.

RESULTS

Patients with RCVS had a reduced number of CD34+KDR+ cells (0.009 ± 0.006% vs. 0.014 ± 0.010%, p = 0.031) but not KDR+CD133+ cells or CD34+CD133+ EPCs, in comparison with controls. The number of CD34+KDR+ cells was inversely correlated with the Lindegaard index (rs = -0.418, p = 0.047). Of note, compared to controls, patients with a Lindegaard index > 2 (n = 13) had a reduced number of CD34+KDR+ cells (0.007 ± 0.005% vs. 0.014 ± 0.010%, p = 0.010), but those with a Lindegaard index ≤ 2 did not.

CONCLUSIONS

Patients with RCVS had reduced circulating CD34+KDR+ EPCs, which were correlated with the severity of vasoconstriction. Endothelial dysfunction might contribute to the pathogenesis of RCVS.

Aneurysmal subarachnoid hemorrhage models: do they need a fix?

The discovery of tissue plasminogen activator to treat acute stroke is a success story of research on preventing brain injury following transient cerebral ischemia (TGI). That this discovery depended upon development of embolic animal model reiterates that proper stroke modeling is the key to develop new treatments. In contrast to TGI, despite extensive research, prevention or treatment of brain injury following aneurysmal subarachnoid hemorrhage (aSAH) has not been achieved. A lack of adequate aSAH disease model may have contributed to this failure. TGI is an important component of aSAH and shares mechanism of injury with it. We hypothesized that modifying aSAH model using experience acquired from TGI modeling may facilitate development of treatment for aSAH and its complications. This review focuses on similarities and dissimilarities between TGI and aSAH, discusses the existing TGI and aSAH animal models, and presents a modified aSAH model which effectively mimics the disease and has a potential of becoming a better resource for studying the brain injury mechanisms and developing a treatment.

Correlation of transcranial color Doppler to n20 somatosensory evoked potential detects ischemic penumbra in subarachnoid hemorrhage

Background:

Normal subjects present interhemispheric symmetry of middle cerebral artery (MCA) mean flow velocity and N20 cortical somatosensory evoked potential (SSEP). Subarachnoid haemorrhage (SAH) can modify this pattern, since high regional brain vascular resistances increase blood flow velocity, and impaired regional brain perfusion reduces N20 amplitude. The aim of the study is to investigate the variability of MCA resistances and N20 amplitude between hemispheres in SAH.

Methods:

Measurements of MCA blood flow velocity (vMCA) by transcranial color-Doppler and median nerve SSEP were bilaterally performed in sixteen patients. MCA vascular changes on the compromised hemisphere were calculated as a ratio of the reciprocal of mean flow velocity (1/vMCA) to contralateral value and correlated to the simultaneous variations of interhemispheric ratio of N20 amplitude, within each subject. Data were analysed with respect to neuroimaging of MCA supplied areas.

Results:

Both interhemispheric ratios of 1/vMCA and N20 amplitude were detected >0.65 (p <0,01) in patients without neuroimages of injury. Both ratios became <0.65 (p <0.01) when patients showed unilateral images of ischemic penumbra and returned >0.65 if penumbra disappeared. The two ratios no longer correlated after structural lesion developed, as N20 detected in the damaged side remained pathological (ratio <0.65), whereas 1/vMCA reverted to symmetric interhemispheric state (ratio >0.65), suggesting a luxury perfusion.

Conclusion:

Variations of interhemispheric ratios of MCA resistance and cortical N20 amplitude correlate closely in SAH and allow identification of the reversible ischemic penumbra threshold, when both ratios become <0.65. The correlation is lost when structural damage develops.

"Optimal cerebral perfusion pressure" in poor grade patients after subarachnoid hemorrhage

BACKGROUND

Cerebrovascular pressure reactivity depends on cerebral perfusion pressure (CPP), with the optimal CPP (CPPopt) defined as pressure at which cerebrovascular reactivity is functioning optimally, reaching minimal value of pressure reactivity index (PRx). The study investigates the association between vasospasm, PRx, and CPPopt in poor grade patients (WFNS 4&5) after subarachnoid hemorrhage (SAH).

METHODS

Data of intracranial pressure (ICP), arterial blood pressure (ABP), and flow velocities (FV) in the Middle Cerebral Artery (MCA) on transcranial Doppler from 42 SAH patients were analyzed retrospectively. PRx was calculated as a correlation coefficient between 10 s mean values of ABP and ICP calculated over a moving 3 min window. Data recorded during the first 48 h were available in 25 cases and during the first 3 days in 29 patients. Recordings obtained from day 4 to day 24 were available in 23 patients.

RESULTS

PRx at optimal CPP measured during the first 48 h showed better cerebrovascular reactivity in patients who were alive at 3 months after ictus than in those who died (PRx value -0.17 +/- 0.05 vs. 0.1 +/- 0.09; P < 0.01). PRx below zero at CPPopt during the first 48 h had 87.5% positive predictive value for survival. CPPopt was lower before than during vasospasm (78 +/- 3 mmHg, N = 29 vs. 98 +/- 4 mmHg; N = 17, P < 0.0001). The overall correlation between CPPopt and Lindegaard ratio was positive (R = 0.39; P < 0.01; N = 45).

CONCLUSION

Most WFNS 4&5 grade SAH patients with PRx below zero at optimal CPP during the first 48 h after ictus survived. Optimal CPP increases during vasospasm.

Xenon-CT and transcranial Doppler in poor-grade or complicated aneurysmatic subarachnoid hemorrhage patients undergoing aggressive management of intracranial hypertension

OBJECTIVE

To evaluate whether elevated flow velocimetry values are associated with critically reduced cerebral blood flow values in deeply sedated patients with acute aneurysmatic subarachnoid hemorrhage and in whom the detection of clinical vasospasm is not feasible.

DESIGN

Retrospective analysis of prospectively collected data.

SETTING

Neurosurgical and trauma patients in an intensive care unit in a regional hospital.

PATIENTS AND PARTICIPANTS

Twenty-nine patients in the acute phase following subarachnoid hemorrhage who were sedated and ventilated for elevated intracranial pressure, transcranial Doppler vasospasm, or respiratory failure and were studied with at least a coupled xenon-CT/transcranial Doppler study.

MEASUREMENTS AND RESULTS

Combined measurement and comparison of cerebral blood flow by means of xenon-CT and of mean velocity by means of transcranial Doppler in middle cerebral artery territories. The case mix studied was consistent with patients' predominantly poor grade and with a complicated course. The results suggest that in sedated patients flow velocity and measured cortical mixed cerebral blood flow are not correlated, and, more specifically, that flow velocities values above 120 or 160 cm/s and Lindegaard index above 3 are not associated with an ischemic regional cerebral blood flow. Conversely, as many as 55% of the xenon-CT studies were associated with hyperemia.

CONCLUSIONS

In patients with elevated intracranial pressure, mean middle cerebral artery flow velocity or Lindegaard Index does not help to detect critical cerebral blood flow nor elevated cerebral blood flow.

Cerebrovascular Dynamics With Head-of-Bed Elevation in Patients With Mild or Moderate Vasospasm After Aneurysmal Subarachnoid Hemorrhage

• Background In patients with aneurysmal subarachnoid hemorrhage, elevation of the head of the bed during vasospasm has been limited in an attempt to minimize vasospasm or its sequelae or both. Consequently, some patients have remained on bed rest for weeks.

• Objectives To determine how elevations of the head of the bed of 20° and 45° affect cerebrovascular dynamics in adult patients with mild or moderate vasospasm after aneurysmal subarachnoid hemorrhage and to describe the response of mild or moderate vasospasm to head-of-bed elevations of 20° and 45° with respect to variables such as grade of subarachnoid hemorrhage and degree of vasospasm.

• Methods A within-patient repeated-measures design was used. The head of the bed was positioned in the sequence of 0°-20°-45°-0° in 20 patients with mild or moderate vasospasm between days 3 and 14 after aneurysmal subarachnoid hemorrhage. Continuous transcranial Doppler recordings were obtained for 2 to 5 minutes after allowing approximately 2 minutes for stabilization in each position.

• ResultsNo patterns or trends indicated that having the head of the bed elevated increases vasospasm. As a group, there were no significant differences within patients at the different positions of the head of the bed. Utilizing repeated-measures analysis of variance, P values ranged from .34 to .97, well beyond .05. No neurological deterioration occurred.

• Conclusions In general, elevation of the head of the bed did not cause harmful changes in cerebral blood flow related to vasospasm.