Oleg Y. Chernyshev

Safety of tPA in stroke mimics and neuroimaging-negative cerebral ischemia

Background: Patients with acute neurologic symptoms may have other causes simulating ischemic stroke, called stroke mimics (SM), but they may also have averted strokes that do not appear as infarcts on neuroimaging, which we call neuroimaging-negative cerebral ischemia (NNCI). We determined the safety and outcome of IV thrombolysis within 3 hours of symptom onset in patients with SM and NNCI. Methods: Patients treated with IV tissue plasminogen activator (tPA) within 3 hours of symptom onset were identified from our stroke registry from June 2004 to October 2008. We collected admission NIH Stroke Scale (NIHSS) score, modified Rankin score (mRS), length of stay (LOS), symptomatic intracerebral hemorrhage (sICH), and discharge diagnosis. Results: Among 512 treated patients, 21% were found not to have an infarct on follow-up imaging. In the SM group (14%), average age was 55 years, median admission NIHSS was 7, median discharge NIHSS was 0, median LOS was 3 days, and there were no instances of sICH. The most common etiologies were seizure, complicated migraine, and conversion disorder. In the NNCI group (7%), average age was 61 years, median admission NIHSS was 7, median discharge NIHSS was 0, median LOS was 3 days, and there were no instances of sICH. Nearly all SM (87%) and NNCI (91%) patients were functionally independent on discharge (mRS 0–1). Conclusions: Our data support the safety of administering IV tissue plasminogen activator to patients with suspected acute cerebral ischemia within 3 hours of symptom onset, even when the diagnosis ultimately is found not to be stroke or imaging does not show an infarct.

Heads down: flat positioning improves blood flow velocity in acute ischemic stroke.

Background: Acute stroke patients are routinely positioned with the head of the bed (HOB) elevated at 30° despite lack of evidence for increased intracranial pressure. Objectives: To determine the effect of HOB positions in real time on residual blood flow velocity in acutely occluded arteries causing stroke and whether resistance to residual flow increased with lower HOB positions. Methods: In a repeated-measures quasi-experiment, the effect of 30, 15, and 0° HOB on middle cerebral artery (MCA) mean flow velocity (MFV) in patients with acute (<24 hours) ischemic stroke was measured with transcranial Doppler using MFV and pulsatility index (PI) of the residual flow signals at the site of persisting acute occlusion. Results: Twenty patients were evaluated (mean age 60 ± 15 years; median NIH Stroke Scale [NIHSS] score 14 points). MCA MFV increased in all patients with lowering head position (maximum absolute MFV value increase 27 cm/s, range 5 to 96% from baseline values at 30°). On average, MCA MFV increased 20% (12% from 30 to 15° and 8% from 15 to 0°; p ≤ 0.025). Mean arterial pressure and heart rate were unchanged throughout the intervention. PI remained unchanged (mean values 0.89 at 30° elevation, 0.91 at 15° elevation, and 0.83 at 0° elevation) at each HOB position, indicating no increase in resistance to blood flow. Immediate neurologic improvement (average 3 NIHSS motor points) occurred in three patients (15%) after lowering head position. Conclusion: Acute ischemic stroke patients may benefit from lower head-of-the-bed positions to promote residual blood flow to ischemic brain tissue.

Yield and Accuracy of Urgent Combined Carotid/Transcranial Ultrasound Testing in Acute Cerebral Ischemia

Background and Purpose— We routinely perform an urgent bedside neurovascular ultrasound examination (NVUE) with carotid/vertebral duplex and transcranial Doppler (TCD) in patients with acute cerebral ischemia. We aimed to determine the yield and accuracy of NVUE to identify lesions amenable for interventional treatment (LAITs). Methods— NVUE was performed with portable carotid duplex and TCD using standardized fast-track (<15 minutes) insonation protocols. Digital subtraction angiography (DSA) was the gold standard for identifying LAIT. These lesions were defined as proximal intra- or extracranial occlusions, near-occlusions, ≥50% stenoses or thrombus in the symptomatic artery. Results— One hundred and fifty patients (70 women, mean age 66±15 years) underwent NVUE at median 128 minutes after symptom onset. Fifty-four patients (36%) received intravenous or intra-arterial thrombolysis (median National Institutes of Health Stroke Scale (NIHSS) score 14, range 4 to 29; 81% had NIHSS ≥10 points). NVUE demonstrated LAITs in 98% of patients eligible for thrombolysis, 76% of acute stroke patients ineligible for thrombolysis (n=63), and 42% in patients with transient ischemic attack (n=33), P<0.001. Urgent DSA was performed in 30 patients on average 230 minutes after NVUE. Compared with DSA, NVUE predicted LAIT presence with 100% sensitivity and 100% specificity, although individual accuracy parameters for TCD and carotid duplex specific to occlusion location ranged 75% to 96% because of the presence of tandem lesions and 10% rate of no temporal windows. Conclusions— Bedside neurovascular ultrasound examination, combining carotid/vertebral duplex with TCD yields a substantial proportion of LAITs in excellent agreement with urgent DSA.

Blood flow velocity and pulsatility index differences in patients with unilateral migraine

Objective.—To evaluate blood flow velocity and pulsatility in unilateral migraine without aura during the headache‐free period using transcranial Doppler (TCD) sonography.

Intracranial Atherosclerosis Is Associated with Progression of Neurological Deficit in Subcortical Stroke

Background: Progression of neurological deficit (PND) is a frequent complication of acute subcortical ischemic stroke (SCS). The role of intracranial atherosclerosis (IAS) in PND is controversial. Our goal was to evaluate IAS on admission, as predictor of PND in SCS patients. Methods: SCS patients were identified from our prospective database from 2004 to 2008. Clinical and laboratory data were collected from charts, and radiographic data from original radiographs. The proximal intracranial arteries were graded as patent, irregular, stenotic, or occlusion. IAS was defined as irregularity or stenosis. PND was defined as a change in the National Institutes of Health Stroke Scale >1 point. Results: Two hundred and two SCS patients were identified. In 14%, PND occurred at a median of 2 days from onset. Univariate analysis by infarct location showed the following to be associated with PND: for anterior circulation infarcts (centrum semiovale/basal ganglia), M1 atherosclerosis (p = 0.042); for posterior circulation infarcts, vertebral artery atherosclerosis (p = 0.018). For both groups, we found a non-significant association with age (p = 0.2) and HbA1c levels (p = 0.095). No association was found with admission glucose levels. Multivariate analysis showed the following association with PND: for anterior circulation infarcts, M1 atherosclerosis (OR 4.7; 95% CI 1.2–18.8; p = 0.03); for pontine infarcts, vertebral artery atherosclerosis (OR 5.8; 95% CI 1.1–29.4; p = 0.033). There was an increase in PND likelihood with an increasing number of atherosclerotic vessels. Discussion: In our cohort of SCS patients, PND was associated with IAS of the responsible vessels. These results suggest a role for IAS in the pathogenesis of PNF in SCS patients.

Nonpulsatile Cerebral Perfusion in Patient With Acute Neurological Deficits

Background and Purpose— An extremely low pulsatile cerebral perfusion can result in a massive cerebral infarction and poor outcome. We report a patient who had complete recovery from initial neurological deficits in spite of nonpulsatile perfusion in the middle cerebral artery. Methods— We used carotid duplex and transcranial Doppler to evaluate cerebral hemodynamics and the National Institutes of Health Stroke Scale (NIHSS) to score the neurological deficits. Results— A 62-year-old man had a sudden chest pain and right hemispheric symptoms with NIHSS score of 18 on arrival. Carotid duplex showed no blood flow in the right common carotid artery. Transcranial Doppler showed a nonpulsatile waveform with slow antegrade flow in right middle cerebral artery. Chest CT angiography revealed type A aortic dissection. After surgical repair for the aortic dissection with brain retroperfusion, the patient had dramatic recovery from the initial neurological deficit, and normal pulsatile cerebral perfusion in the right carotid territory. Conclusions— Nonpulsatile cerebral perfusion points to a proximal source of arterial flow obstruction that may necessitate interventional treatment or surgery in order to restore brain perfusion and potentially reverse impending stroke.

A pilot study: portable out-of-center sleep testing as an early sleep apnea screening tool in acute ischemic stroke.

Introduction Prompt diagnosis of obstructive sleep apnea (OSA) after acute ischemic stroke (AIS) is critical for optimal clinical outcomes, but in-laboratory conventional polysomnograms (PSG) are not routinely practical. Though portable out-of-center type III cardiopulmonary sleep studies (out-of-center cardiopulmonary sleep testing [OCST]) are widely available, these studies have not been validated in patients who have recently suffered from AIS. We hypothesized that OCST in patients with AIS would yield similar results when compared to conventional PSG. Methods Patients with AIS had simultaneous type III OCST and PSG studies performed within 72 hours from symptom onset. The accuracy of OCST was compared to PSG using: chi-square tests, receiver operatory characteristic curves, Bland–Altman plot, paired Student’s t-test/Wilcoxon signed-rank test, and calculation of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results Twenty-one out of 23 subjects with AIS (age 61±9.4 years; 52% male; 58% African-American) successfully completed both studies (9% technical failure). Nearly all (95%) had Mallampati IV posterior oropharynx; the mean neck circumference was 16.8±1.6 in. and the mean body mass index (BMI) was 30±7 kg/m2. The apnea hypopnea index (AHI) provided by OCST was similar to that provided by PSG (19.8±18.0 vs 22.0±22.7, respectively; P=0.49). On identifying subjects by OCST with an AHI ≥5 on PSG, OCST had the following parameters: sensitivity 100%, specificity 85.7%, PPV 93%, and NPV 100%. On identifying subjects with an AHI ≥15 on PSG, OCST parameters were as follows: sensitivity 100%, specificity 83.3%, PPV 81.8%, and NPV 100%. Bland–Altman plotting showed an overall diagnostic agreement between OCST and PSG modalities for an AHI cutoff >5, despite fine-grained differences in estimated AHIs. Conclusion Compared with PSG, OCST provides similar diagnostic information when run simultaneously in AIS patients. OCST is a reliable screening tool for early diagnosis of OSA in AIS patients.

Neurological Respiratory Failure

West Nile virus infection in humans is mostly asymptomatic. Less than 1% of neuro-invasive cases show a fatality rate of around 10%. Acute flaccid paralysis of respiratory muscles leading to respiratory failure is the most common cause of death. Although the peripheral nervous system can be involved, isolated phrenic nerve palsy leading to respiratory failure is rare and described in only two cases in the English literature. We present another case of neurological respiratory failure due to West Nile virus-induced phrenic nerve palsy. Our case reiterates the rare, but lethal, consequences of West Nile virus infection, and the increase of its awareness among physicians.

Coexistence of obstructive sleep apnea worsens the overall outcome of intracranial aneurysm: a pioneer study.

OBJECTIVE Obstructive sleep apnea (OSA) is associated with the progression of abdominal and thoracic aortic aneurysms. However, the role of OSA in the overall outcome of intracranial aneurysms (IAs) has not yet been established. Authors of this report investigated the role of OSA in the overall outcome of IAs. METHODS Radiological and clinical data on patients (from 2010 through 2015) with confirmed IA were retrospectively reviewed. Significant differences between the OSA and non-OSA groups were determined using a chi-square test. Logistic regression analysis was performed to identify the predictors of an unfavorable IA outcome. RESULTS Among the 283 patients with confirmed IAs, 45 patients (16%) were positively screened for OSA, a proportion that was significantly higher than the prevalence of OSA in nonaneurysmal neurosurgical patients (4%, p = 0.008). The percentage of patients with hypertension (p = 0.018), a body mass index ≥ 30 kg/m2 (p < 0.0001), hyperlipidemia (p = 0.034), diabetes mellitus (p = 0.005), chronic heart disease (CHD; p = 0.024), or prior stroke (p = 0.03) was significantly higher in the OSA group than in the non-OSA group. Similarly, the percentage of wide-necked aneurysms (p = 0.00001) and patients with a poor Hunt and Hess Grade IV-V (p = 0.01) was significantly higher in the OSA group than in the non-OSA group. In addition, the percentage of ruptured aneurysms (p = 0.03) and vasospasms (p = 0.03) was significantly higher in the OSA group. The percentage of patients with poor modified Rankin Scale (mRS) scores (3-6) was significantly higher in the OSA group (p = 0.03). A separate cohort of patients with ruptured IAs showed similar results. In both univariate (p = 0.01) and multivariate (p = 0.04) regression analyses, OSA was identified as an individual predictor of an unfavorable outcome. In addition, hypertension and prior stroke were revealed as predictors of a poor IA outcome. CONCLUSIONS Complications of IA such as rupture and vasospasm are often the consequence of uncontrolled OSA. Overall outcome (mRS) of IAs is also affected by the co-occurrence of OSA. Therefore, the coexistence of OSA with IA affects the outcome of IAs. Obstructive sleep apnea is a risk factor for a poor outcome in IA patients.