Whole brain CT perfusion combined with CT angiography in patients with subarachnoid hemorrhage and cerebral vasospasm

Objective

To assess cerebral vasospasm (CVS) and monitor cerebral microcirculatory changes in patients with acute subarachnoid hemorrhage (SAH) via CT angiography (CTA) combined with whole-brain CT perfusion (CTP) techniques.

Methods

Sixty patients with SAH (SAH group) and 10 patients without SAH (control group) were selected for a prospective study. CTP combined with CTA and digital subtraction angiography (DSA) studies were performed on patients with initial onset of SAH less than three days. CTA and DSA as well as the CTP parameters such as cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time-to-peak (TTP) were acquired and analyzed. The relationship of CTA and CTP measurements was assessed in these acute SAH patients.

Results

CTP techniques were used to achieve the perfusion maps of the whole brain in patients with acute SAH. Compared to the control group, mean CBF value was significantly lower while both MTT and TTP values were significantly higher in SAH group (all p < 0.05). Further analysis revealed that mean CBF in patients with CVS, sCVS, Fisher III–IV and Hunt–Hess III–V significantly decreased when compared to patients with nCVS, asCVS, Fisher I–II and Hunt–Hess I–II (p < 0.05). Furthermore both MTT and TTP values were also significantly reduced in patient with CVS, sCVS, Fisher III–IV and Hunt–Hess III–V (p < 0.05).

Conclusion

The study demonstrated that changes of microcirculation in patients with SAH could be assessed by whole-brain CTP. CTP combined with CTA could detect both macroscopic evident vasospasm on CTA and alterations of microcirculation on CTP. Mean CBF was significantly lower in patients with SAH.     

Computed Tomography Angiography in the Diagnosis Of Brain Death: A Systematic Review and Meta-Analysis

Background

Physiological instability and confounding factors may interfere with the clinical diagnosis of brain death. Computed tomography angiography (CTA) has been suggested as a potential ancillary test for confirmation of brain death, but its diagnostic accuracy remains unclear.

Methods

We searched MEDLINE, EMBASE, and CENTRAL for studies comparing CTA with other accepted methods of diagnosing brain death (clinical or radiographic). Summary estimates of diagnostic accuracy were computed using random effects models. Subgroup analyses and meta-regression were performed to assess associations between CTA sensitivity and study or patient characteristics.

Results

Twelve studies, involving 541 patients, were included. If the CTA criterion for brain death was complete lack of opacification of intracranial vessels, then the pooled sensitivity was 62 % (50–74 %) for venous phase and 84 % (75–94 %) for arterial phase imaging. The sensitivity of CTA was higher when the criterion for brain death involved absence of opacification of internal cerebral veins, either alone (99 %, 97–100 %) or in combination with lack of flow to the distal middle cerebral artery branches (85 %, 77–93 %). CTA sensitivity was not influenced by different reference standards (clinical vs. radiographic) or predominant diagnostic category (stroke vs. brain trauma). Specificity of CTA could not be adequately determined from the existing data.

Conclusion

Many patients who progress to brain death by accepted clinical or radiographic criteria have persistent opacification of proximal intracranial vessels when CTA is performed. The specificity of CTA in the diagnosis of brain death has not been adequately assessed. Routine use of CTA as an ancillary test in the diagnosis of brain death is therefore not recommended until diagnostic criteria have undergone further refinement and prospective validation. Absence of opacification of the internal cerebral veins appears to be the most promising angiographic criterion.     

Pressures,Flow, and Brain Oxygenation During Plateau Waves of Intracranial Pressure

Background

Plateau waves are common in traumatic brain injury. They constitute abrupt increases of intracranial pressure (ICP) above 40 mmHg associated with a decrease in cerebral perfusion pressure (CPP). The aim of this study was to describe plateau waves characteristics with multimodal brain monitoring in head injured patients admitted in neurocritical care.

Methods

Prospective observational study in 18 multiple trauma patients with head injury admitted to Neurocritical Care Unit of Hospital Sao Joao in Porto. Multimodal systemic and brain monitoring of primary variables [heart rate, arterial blood pressure, ICP, CPP, pulse amplitude, end tidal CO₂, brain temperature, brain tissue oxygenation pressure, cerebral oximetry (CO) with transcutaneous near-infrared spectroscopy and cerebral blood flow (CBF)] and secondary variables related to cerebral compensatory reserve and cerebrovascular reactivity were supported by dedicated software ICM+ (www.neurosurg.cam.ac.uk/icmplus). The compiled data were analyzed in patients who developed plateau waves.

Results

In this study we identified 59 plateau waves that occurred in 44 % of the patients (8/18). During plateau waves CBF, cerebrovascular resistance, CO, and brain tissue oxygenation decreased. The duration and magnitude of plateau waves were greater in patients with working cerebrovascular reactivity. After the end of plateau wave, a hyperemic response was recorded in 64 % of cases with increase in CBF and brain oxygenation. The magnitude of hyperemia was associated with better autoregulation status and low oxygenation levels at baseline.

Conclusions

Multimodal brain monitoring facilitates identification and understanding of intrinsic vascular brain phenomenon, such as plateau waves, and may help the adequate management of acute head injury at bed side.     

Brain CT perfusion improves intracranial vessel occlusion detection on CT angiography

Background and purpose

To evaluate whether brain CT perfusion (CTP) aids in the detection of intracranial vessel occlusion on CT angiography (CTA) in acute ischemic stroke.

Changes in Cerebral Perfusion with Induced Hypertension in Aneurysmal Subarachnoid Hemorrhage: A Pilot and Feasibility Study

Background

The effects of induced hypertension (IH) on cerebral perfusion after subarachnoid hemorrhage (SAH) are unclear. The objectives of this investigation are to: (1) determine whether there are differences in cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) measured with computed tomography perfusion (CTP) before and after IH; (2) evaluate differences in the presence of infarction and clinical outcome between patients with and without IH.

Methods

We performed a retrospective cohort analysis of 25 aneurysmal SAH patients. IH was initiated as per the standard institutional protocol when patients showed clinical symptoms of delayed cerebral ischemia (DCI). Differences in CBF, CBV, and MTT between early (<72 h after aneurysm rupture) and late (7–10 days after aneurysm rupture) CTP were quantified in patients with (n = 13) and without IH (n = 12). Outcome measures included cerebral infarction and clinical outcome at 3 months.

Results

Early MTT was significantly greater in the IH group compared to the no-IH group. There was no difference in early or late CBV or CBF between the two groups. In patients that received IH, there was a significant decrease in MTT between the early (7.0 ± 1.2 s) and late scans (5.8 ± 1.6 s; p = 0.005). There was no difference in the incidence of infarction (5/13 vs. 2/11) or poor outcome (3/11 vs. 6/13) between the IH and no-IH groups, respectively (p > 0.05).

Conclusions

Elevated MTT is a significant factor for the development of DCI in patients eventually requiring IH therapy and is improved by IH treatment. Therapies to prevent DCI and improve clinical outcome may need to be initiated earlier, when cerebral perfusion abnormalities are first identified.

     

The Use of Transcranial Doppler Ultrasound in Confirming Brain Death in the Setting of Skull Defects and Extraventricular Drains

Background

Transcranial Doppler ultrasound (TCD) has been used as a confirmatory test for the diagnosis of brain death (BD), but may be inaccurate in patients with a skull defect or extraventricular drain (EVD).

Methods and Results

We report three cases of patients with a skull defect or EVD in whom TCD supported a diagnosis of BD but in which the clinical examination later refuted the diagnosis.

Conclusion

We caution against the use of TCD to confirm the diagnosis of BD in the presence of a skull defect or EVD.     

Low rate of contrast-induced Nephropathy after CT perfusion and CT angiography in acute stroke patients

Background

The aim of the study was to assess (i) the rate of contrast-induced nephropathy (CIN), (ii) the amount and time course of renal dysfunction, (iii) the identification of risk factors and calculation of a risk score for CIN in acute stroke patients after CT perfusion (CTP) and CT angiography (CTA).

Methods

162 patients were investigated,who had received 140 ml of non-ionic low osmolar contrast agent (300 mg iodine per ml, Ultravist 300^®, Schering AG) for CTA and CTP. We assessed electrolytes, creatinine, and creatinine clearance before and up to 7 days after administration of contrast agent. In addition, the risk factors for CIN were recorded and a previously validated risk score for CIN was calculated.We also assessed the amount of crystalloid fluid substitution and newly prescribed drugs. CIN was defined as an increase of the serum creatinine-level of > 0.5 mg/dl or > 25% above baseline within 48 hours after contrast agent administration.

Results

154 patients (94 %) received crystalloid fluid substitution (mean 6.1 l) within 48 h after contrast agent administration. During follow-up the creatinine values and the creatinine clearance remained stable while sodium and potassium increased significantly (p < 0.0001) after contrast agent administration. In patients with a pathological creatinine value on admission (n = 40), the creatinine clearance did not decrease significantly (p = 0.18). The risk score for developing a CIN was low in the majority of stroke patients. A manifest CIN occurred in 3 patients (2 %). No patient had to be hemodialysed.

Conclusion

CIN is a rare complication in acute stroke patients examined by multimodal contrast-based CT due to the low prevalence of risk factors associated with CIN. In conjunction with appropriate fluid substitution, low osmolar nonionic contrast agents seem to be safe in clinical routine.

     

Dual-Energy CT to Diagnose Pseudoedema in Contrast-Induced Encephalopathy Following Cerebral Angiography

Background

Contrast-induced encephalopathy (CIE) is a syndrome that may be clinically unrecognized and misdiagnosed as cerebral edema.

Methods

Case report and review.

Results

A 72-year-old woman was admitted for elective endovascular embolization of a 10-mm left anterior communicating artery aneurysm. One hour post-procedure, she acutely developed global aphasia. Emergent head computed tomography (CT) and computed tomography-angiography (CTA) showed high attenuation of the left hemispheric subarachnoid spaces interpreted as hemispheric edema; emergent magnetic resonance imaging revealed left hemispheric punctate infarcts. At 12 h, she developed right hemiparesis and encephalopathy. Repeat CTA and CT perfusion revealed decreased left hemisphere cerebral blood flow and diminutive caliber of distal left middle cerebral artery territory vasculature. Repeated angiography with intra-arterial verapamil and systemic blood pressure augmentation were performed for presumed vasospasm. At 20 h, head CT was concerning for worsening left hemispheric edema, but dual-energy, iodine-subtracting sequences revealed significant contrast extravasation contributing to the appearance of sulcal effacement but without actual edema. Out of concern for blood–brain barrier breakdown from CIE, pressor augmentation was discontinued and the patient gradually improved to full neurological recovery within 72 h of symptom onset.

Conclusions

Our case is the first known to report the use of dual-energy, iodine-subtracting CT as a diagnostic tool in differentiating between cerebral edema and pseudoedema in CIE.

     

Continuous Electroencephalography (cEEG) Changes Precede Clinical Changes in a Case of Progressive Cerebral Edema

Background

Continuous electroencephalogram (cEEG) is tightly linked to cerebral metabolism and is sensitive to cerebral ischemia and hypoxia. The severity of cerebral ischemia can be seen on cEEG as changes in morphology, amplitude, or frequency, and cEEG may detect neuronal dysfunction at a reversible stage.

Methods

Case report and imaging.

Results

We present a case of focal cerebral edema with changes seen on cEEG 24 h before clinical signs of increased intracranial pressure. cEEG showed developing asymmetry in the left hemisphere followed by burst suppression. The right hemisphere showed similar progression to burst suppression. Complete suppression of both hemispheres was noted 6 h before clinical signs of herniation. Computed tomography (CT) head confirmed a large left parietal intracerebral hematoma with mass effect.

Conclusions

cEEG has applications in monitoring cerebral dysfunction in addition to detecting seizure activity in the intensive care unit. It may serve a vital role in multi-modality monitoring for early recognition of neurological complications from brain injuries that may not be noticed clinically, which is paramount to early intervention.     

Consideration of the Intracranial Pressure Threshold Value for the Initiation of Traumatic Brain Injury Treatment: A Xenon CT and Perfusion CT Study

Background

Monitoring of intracranial pressure (ICP) is considered to be fundamental for the care of patients with severe traumatic brain injury (TBI) and is routinely used to direct medical and surgical therapy. Accordingly, some guidelines for the management of severe TBI recommend that treatment be initiated for ICP values >20 mmHg. However, it remained to be accounted whether there is a scientific basis to this instruction. The purpose of the present study was to clarify whether the basis of ICP values >20 mmHg is appropriate.

Subject and Methods

We retrospectively reviewed 25 patients with severe TBI who underwent neuroimaging during ICP monitoring within the first 7 days. We measured cerebral blood flow (CBF), mean transit time (MTT), cerebral blood volume (CBV), and ICP 71 times within the first 7 days.

Results

Although the CBF, MTT, and CBV values were not correlated with the ICP value at ICP values ≤20 mmHg, the CBF value was significantly negatively correlated with the ICP value (r = ?0.381, P < 0.05) at ICP values >20 mmHg. The MTT value was also significantly positively correlated with the ICP value (r = 0.638, P < 0.05) at ICP values >20 mmHg.

Conclusion

The cerebral circulation disturbance increased with the ICP value. We demonstrated the cerebral circulation disturbance at ICP values >20 mmHg. This study suggests that an ICP >20 mmHg is the threshold to initiate treatments. An active treatment intervention would be required for severe TBI when the ICP was >20 mmHg.

     

Multiple encephalogaleoperiosteal synangiosis for bilateral carotid artery stenosis in a 13-year-old girl: a case report

Introduction

Encephalogaleoperiosteal synangiosis (EGS) has been widely used to treat children with moyamoya disease (MMD). We present the first case of successful multiple EGS in a patient with brain ischemic disease who presented with different cerebrovascular findings from MMD.

Methods

A 13-year-old girl had an increased frequency of transient ischemic attacks that affected her right extremities. Digital subtraction angiography showed tapering of the internal carotid artery (ICA). The anterior cerebral artery (ACA) and middle cerebral artery (MCA) were visible on vertebral angiogram, but not on carotid angiogram. The intact circle of Willis and lack of hypervascularity of the lenticulostriate arteries were observed. Decreased regional cerebral blood flow (CBF) in the bilateral ACA and MCA territories quantified by ¹²³I-N-isopropyl-p-iodoamphetamine-single photon emission computed tomography indicated the need for extracranial-intracranial bypass surgery. Multiple EGS procedures were performed instead of direct anastomosis, which is the standard procedure for intracranial ICA stenosis, because the space for the craniotomy was limited by transdural anastomosis.

Results

Despite the fact that the diagnosis of MMD was questionable, the hemispheres were well vascularized, and the neurology and CBF improved postoperatively.

Conclusion

The preserved circle of Willis and lack of moyamoya vessels were inconsistent with the features of MMD. However, childhood onset, bilateralness, chronic intracranial ICA stenosis, and transdural anastomosis indicated the same underling pathogenicity as MMD. It is hypothesized that ICA stenosis occurred immediately proximal to the posterior communicating artery in this case. This would have produced the atypical finding of the remaining circle of Willis without growth of the basal moyamoya vessels.

     

Impact of Methamphetamine on Regional Metabolism and Cerebral Blood Flow After Traumatic Brain Injury

Background

Substance abuse is a frequent comorbid condition among patients with traumatic brain injury (TBI), but little is known about its potential additive or interactive effects on tissue injury or recovery from TBI. This study aims to evaluate changes in regional metabolism and cerebral perfusion in subjects who used methamphetamine (METH) prior to sustaining a TBI. We hypothesized that METH use would decrease pericontusional cerebral perfusion and markers of neuronal metabolism, in TBI patients compared to those without METH use.

Methods

This is a single center prospective observational study. Adults with moderate and severe TBI were included. MRI scanning was performed on a 3 Tesla scanner. MP-RAGE and FLAIR sequences as well as Metabolite spectra of NAA and lactate in pericontusional and contralateral voxels identified on the MP-RAGE scans. A spiral-based FAIR sequence was used for the acquisition of cerebral blood flow (CBF) maps. Regional CBF images were analyzed using ImageJ open source software. Pericontusional and contralateral CBF, NAA, and lactate were assessed in the entire cohort and in the METH and non-METH groups.

Results

Seventeen subjects completed the MR studies. Analysis of entire cohort: pericontusional NAA concentrations (5.81 ± 2.0 mM/kg) were 12 % lower compared to the contralateral NAA (6.98 ± 1.2 mM/kg; p = 0.03). Lactate concentrations and CBF were not significantly different between the two regions; however, regional CBF was equally reduced in the two regions. Subgroup analysis: 41 % of subjects tested positive for METH. The mean age, Glasgow Coma Scale, and time to scan did not differ between groups. The two subject groups also had similar regional NAA and lactate. Pericontusional CBF was 60 % lower in the METH users than the non-users, p = 0.04; contralateral CBF did not differ between the groups.

Conclusion

This small study demonstrates that tissue metabolism is regionally heterogeneous after TBI and pericontusional perfusion was significantly reduced in the METH subgroup.     

A successful treatment of arterial ischemic stroke with stent insertion in a child with congenital heart disease

Introduction

Diagnosis of arterial ischemic stroke in pediatric patients is often delayed due to the uncertainty and variability of clinical symptoms. Early diagnosis of arterial ischemic stroke can bring a favorable prognosis with prompt thrombolytic therapy or stent insertion, via transfemoral cerebral arteriogram. Acute thrombolytic therapy is rarely attempted in children because of the delayed diagnosis.

Patient and method

We report a case of a 4-year-old girl with complex heart disease who was presented with arterial ischemic stroke at the right distal internal carotid artery and successfully treated by stent insertion in which repeated thrombolysis or ballooning had failed.

Result

Left hemiparesis was nearly recovered 6 days after the stent insertion. The mean flow velocity of the right middle cerebral artery has slightly improved compared to that of the initial study. She has been followed-up for 6 months in the outpatient clinic without neurologic sequelae.

Conclusion

This case suggests that intracranial stent insertion may be a safe and an effective modality in young children, when the thrombolytic therapy or ballooning is inapplicable. Additionally, transcranial Doppler ultrasonography is useful to monitor the cerebral blood flow after stent insertion in children.     

Cerebral Blood Flow and Transcranial Doppler Sonography Measurements of CO2-Reactivity in Acute Traumatic Brain Injured Patients

Background

Cerebral blood flow (CBF) measurements are helpful in managing patients with traumatic brain injury (TBI), and testing the cerebrovascular reactivity to CO₂ provides information about injury severity and outcome. The complexity and potential hazard of performing CBF measurements limits routine clinical use. An alternative approach is to measure the CBF velocity using bedside, non-invasive, and transcranial Doppler (TCD) sonography. This study was performed to investigate if TCD is a useful alternative to CBF in patients with severe TBI.

Method

CBF and TCD flow velocity measurements and cerebrovascular reactivity to hypocapnia were simultaneously evaluated in 27 patients with acute TBI. Measurements were performed preoperatively during controlled normocapnia and hypocapnia in patients scheduled for hematoma evacuation under general anesthesia.

Main Finding and Conclusion

Although the lack of statistical correlation between the calculated reactivity indices, there was a significant decrease in TCD-mean flow velocity and a decrease in CBF with hypocapnia. CBF and TCD do not seem to be directly interchangeable in determining CO₂-reactivity in TBI, despite both methods demonstrating deviation in the same direction during hypocapnia. TCD and CBF measurements both provide useful information on cerebrovascular events which, although not interchangeable, may complement each other in clinical scenarios.     

Sphenoid and Subdural Hemorrhage as a Presenting Sign of Ruptured Clinoid Aneurysm

Background

Aneurysm rupture presenting as an isolated or pure subdural hematoma (SDH) without subarachnoid hemorrhage is an extremely rare radiographic presentation. We present a case of a ruptured internal carotid artery aneurysm with a pure SDH and concurrent sphenoid sinus hemorrhage.

Methods

Case report and review of the literature.

Results

We describe a case of a 48-year-old right-handed woman found comatose brought by emergency medical services to an outside hospital. A non-contrast head CT scan demonstrated bilateral acute SDHs without evidence of intraparenchymal or subarachnoid hemorrhage. A CT angiogram of the head showed a focal hyperdensity in the distal left internal carotid artery (ICA) and was confirmed by conventional cerebral angiography to be a 7-mm left supraclinoid ICA aneurysm. On repeat CT scan a new hemorrhage was seen in the sphenoid sinus indicating a re-bleeding. The aneurysm was treated with coil embolization and complete occlusion was confirmed with subsequent angiograms. The patient had an eventful hospital course complicated by a Takotsubo cardiomyopathy and pulmonary edema. She was medically treated with successful recovery of her cardiopulmonary function. She remained markedly disabled and was transferred to an inpatient rehabilitation center for continued convalescence.

Conclusions

Acute subdural hematoma may be due to a ruptured clinoid carotid aneurysm. Acute hemorrhage into the sphenoid sinus can be an important clue.     

Acute Effect of Intravenous Sildenafil on Cerebral Blood Flow in Patients with Vasospasm After Subarachnoid Hemorrhage

Background

The phosphodiesterase-5 inhibitor sildenafil has been shown to attenuate delayed cerebral ischemia (DCI) and improve neurologic function in experimental subarachnoid hemorrhage (SAH). We recently demonstrated that it could improve cerebral vasospasm (CVS) in humans after SAH. However, successful therapies for DCI must also restore cerebral blood flow (CBF) and/or autoregulatory capacity. In this study, we tested the effects of sildenafil on CBF in SAH patients at-risk for DCI.

Methods

Six subjects with angiographically confirmed CVS received 30-mg of intravenous sildenafil (mean 9 ± 2 days after aneurysmal SAH). Each underwent ¹⁵O-PET imaging to measure global and regional CBF at baseline and post-sildenafil.

Results

Mean arterial pressure declined by 10 mm Hg on average post-sildenafil (8 %, p = 0.01), while ICP was unchanged. There was no change in global CBF (mean 34.5 ± 7 ml/100g/min at baseline vs. 33.9 ± 8.0 ml/100g/min post-sildenafil, p = 0.84). The proportion of brain regions with low CBF (<25 ml/100g/min) was also unchanged after sildenafil infusion.

Conclusions

Infusion of sildenafil does not lead to a change in global or regional perfusion despite a significant reduction in cerebral perfusion pressure. While this could reflect the ineffectiveness of sildenafil-induced proximal vasodilatation to alter brain perfusion, it also suggests that cerebral autoregulatory function was preserved in this group. Future studies should assess whether sildenafil can restore or enhance autoregulation after SAH.

     

Iatrogenic intracranial aneurysms in childhood: case-based update

Purpose

Iatrogenic aneurysms are very rare in children. Characteristic clinical manifestations are variable and asymptomatic course is possible especially for fusiform dilatation of internal carotid artery. Even though radiological diagnosis is easy, the management of iatrogenic intracranial aneurysm is still a subject for discussion.

Methods

Fusiform dilatations of internal carotid artery were diagnosed on three pediatric patients during follow-up imaging after primary surgery for suprasellar–parasellar tumor. All patients were asymptomatic. Conservative treatment was proposed because the lesion did not show any progression in subsequent examinations. Patients are stable under conservative treatment.

Conclusions

Iatrogenic aneurysm may have an unusual presentation and their therapy still remains unclear. Fusiform dilatation of internal carotid artery rarely causes symptoms and there is no published paper of subarachnoid bleeding. Treatment would be difficult, since the main arterial branches arise from the dilated carotid segment. Conservative treatment is a choice only if aneurysm has no progression or in case of spontaneous healing. Intervention should be performed only in case of progression or if the aneurysm becomes symptomatic.     

Variability in Brain Death Determination in Europe: Looking for a Solution

Background

Criteria for determining brain death (BD) vary between countries. We report the results of an investigation designed to compare procedures to determine BD in different European countries.

Methods

We developed a web-based questionnaire that was sent to representatives of 33 European countries. Responses were reviewed, and individual respondents were contacted if clarification was required.

Results

Responses were received from 28 (85 %) of the 33 countries to which the questionnaire was sent. Each country has either a law (93 %) or national guidance (89 %) for defining BD. Clinical examination is sufficient to determine BD in 50 % of countries; coma, apnea, absence of corneal, and cough reflexes are mandatory criteria in all. Confirmation of apnea is required in all countries but not defined in 4 (14 %). In the 24 (86 %) of countries with a formal definition of the apnea test, a target pCO₂ level (23/24, 96 %) is the pre-specified end point in most. The (median, range) number of clinical examinations (2, 1–3) and minimum observation time between tests (3 h, 0–12 h) vary greatly between countries. Additional (confirmatory) tests are required in 50 % of countries. Hypothermia (4 %), anoxic injury (7 %), inability to complete clinical examination (61 %), toxic drug levels (57 %), and inconclusive apnea test (54 %) are among the most common indications for confirmatory tests. Cerebral blood flow (CBF) investigation is mandatory in 18 % of countries, but optional or indicated only in selected cases in 82 %. Conventional angiography is the preferred method of determining absent CBF (50 %), followed by transcranial Doppler sonography (43 %), computerized tomography (CT) angiography (39 %), CT perfusion, and magnetic resonance imaging (MRI) angiography (11 %). Electroencephalography is always (21 %) or optionally (14 %) recorded.

Conclusions

Although legislation or professional guidance is available to standardize nationally the BD diagnosis process in all European countries, there are still disparities between countries. The current variation in practice makes an international consensus for the definition of BD imperative.     

Plantar Flexion with Noxious Dorsal Foot Stimulation in Brain Death

Background

Plantar flexion with plantar stimulation has been well described in brain death, and is compatible with brain death. However, plantar flexion with stimulation to the dorsal surface of the foot has not been reported previously in brain dead patients.

Methods

Case report with Technetium-99?m hexamethylpropyleneamine oxime brain scan and video.

Results

A 46-year-old woman suffered severe anoxic brain injury following massive pulmonary embolism 5?days after arthroscopic knee surgery. Neurologic examination was consistent with brain death, with the exception of plantar flexion when noxious stimulation was applied to the dorsal surface of the great toe on each side. Ancillary testing with a technetium-99?m nuclear scan demonstrated absence of cerebral perfusion, supporting the diagnosis of brain death.

Conclusions

Noxious stimulation to the dorsal surface of the foot may trigger spinally mediated plantar flexion in patients with brain death.     

Default Mode Network Perfusion in Aneurysmal Subarachnoid Hemorrhage

Background

The etiology of altered consciousness in patients with high-grade aneurysmal subarachnoid hemorrhage (SAH) is not thoroughly understood. We hypothesized that decreased cerebral blood flow (CBF) in brain regions critical to consciousness may contribute.

Methods

We retrospectively evaluated arterial-spin labeled (ASL) perfusion magnetic resonance imaging (MRI) measurements of CBF in 12 patients with aneurysmal SAH admitted to our neurocritical care unit. CBF values were analyzed within gray matter nodes of the default mode network (DMN), whose functional integrity has been shown to be necessary for consciousness. DMN nodes studied were the bilateral medial prefrontal cortices, thalami, and posterior cingulate cortices. Correlations between nodal CBF and admission Glasgow Coma Scale (GCS) score, admission Hunt and Hess (HH) class, and GCS score at the time of MRI (MRI GCS) were tested.

Results

Spearman’s correlation coefficients were not significant when comparing admission GCS, admission HH, and MRI GCS versus nodal CBF (p > 0.05). However, inter-rater reliability for nodal CBF was high (r = 0.71, p = 0.01).

Conclusions

In this retrospective pilot study, we did not identify significant correlations between CBF and admission GCS, admission HH class, or MRI GCS for any DMN node. Potential explanations for these findings include small sample size, ASL data acquisition at variable times after SAH onset, and CBF analysis in DMN nodes that may not reflect the functional integrity of the entire network. High inter-rater reliability suggests ASL measurements of CBF within DMN nodes are reproducible. Larger prospective studies are needed to elucidate whether decreased cerebral perfusion contributes to altered consciousness in SAH.