Hemorrhagic transformation in patients with acute ischaemic stroke and an indication for anticoagulation

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) can occur in patients following acute ischaemic stroke in the form of hemorrhagic transformation, and results in significant long-term morbidity and mortality. Anticoagulation theoretically increases risk. We evaluated stroke patients with an indication for anticoagulation to determine the factors associated with hemorrhagic transformation.

METHODS

Three-hundred and forty-five patients with ICD-9 codes indicating: (i) acute ischaemic stroke; and (ii) an indication for anticoagulation were screened. One-hundred and twenty-three met inclusion criteria. Data were collected retrospectively. Neuroimaging was reviewed for infarct volume and evidence of ICH. Hemorrhages were classified as: hemorrhagic conversion (petechiae) versus intracerebral hematoma (a space occupying lesion); symptomatic versus asymptomatic. Using multivariable logistic regression, we determined the hypothesized factors associated with intracerebral bleeding.

RESULTS

Age [odds ratio (OR) = 1.50 per 10-year increment, 95% confidence interval (CI) 1.07-2.08], infarct volume (OR = 1.10 per 10 ccs, 95% CI 1.06-1.18) and worsening category of renal impairment by estimated glomerular filtration rate (eGFR; OR = 1.95, 95% CI 1.04-3.66) were predictors of hemorrhagic transformation. Ninety- nine out of 123 patients were anticoagulated. Hemorrhage rates of patients on and off anticoagulation did not differ (25.3% vs. 20.8%; P = 0.79); however, all intracerebral hematomas (n = 7) and symptomatic bleeds (n = 8) occurred in the anticoagulated group.

CONCLUSIONS

The risk of hemorrhagic transformation in patients with acute ischaemic stroke and an indication for anticoagulation is multifactorial, and most closely associated with an individual's age, infarct volume and eGFR.

Deferiprone reduces hemosiderin deposits in the brain of a patient with superficial siderosis

A man with superficial siderosis showed improvement in symptoms and reduction in hemosiderin by MR imaging following treatment with deferiprone, a lipid-soluble iron chelator.

Stroke treatment: beyond the three-hour window and in the pregnant patient

For acute stroke patients who arrive at the hospital within 3 h of symptom onset, the focus of care involves screening for eligibility to receive intravenous tissue plasminogen activator. The publication of the National Institute of Neurological Disorders and Stroke recombinant tissue-type plasminogen activator (tPA, or alteplase) study in 1995 (Marler, J.R. 1995, New England Journal of Medicine333: 1581-1587) spurred protocol changes, which continue to evolve, throughout the health care system in an effort to streamline the patient through the Emergency Medical System. The need to expedite patient evaluation involving emergency department, laboratory, radiology, and clinical neurology testing is clear and has been a focus of many stroke centers. For some patients, intravenous thrombolysis within 3 h has a dramatic effect on outcome. However, that is not the only course of action for acute stroke patients. This article will review some of the effective treatments for stroke patients beyond the first 3 h of their care.

Diffusion-weighted imaging and National Institutes of Health Stroke Scale in the acute phase of posterior-circulation stroke

BACKGROUND

Occlusive disease of the posterior circulation represents a heterogeneous group of strokes that differ in etiology, clinical presentation, and prognosis. Computed tomography provides suboptimal visualization of posterior-circulation infarcts. Anatomic definition of traditional magnetic resonance imaging sequences has been used for clinicoradiologic correlation in patients with posterior-circulation disease. These studies focused on the subacute rather than the acute phase of ischemia. Lesion volumes on diffusion-weighted imaging (DWI) and perfusion imaging were found to have a good correlation with 24-hour National Institutes of Health stroke scale (NIHSS) score in ischemia of the anterior circulation. Correlation between NIHSS score and lesion volume in posterior-circulation infarcts is unknown.

OBJECTIVES

To investigate whether DWI is useful for clinicoradiologic correlation of posterior-circulation ischemia within 24 hours after symptom onset and whether NIHSS score correlates with lesion volumes in patients with posterior-circulation stroke.

PATIENTS AND METHODS

In a database analysis of 631 patients with stroke from June 26, 1996, to July 30, 1999, 115 patients (18%) had symptoms of posterior-circulation ischemia by imaging and clinical criteria. Among these 115, we included all patients (n = 40) who underwent DWI within 24 hours from symptom onset (mean, 9.7 +/- 7.1 hours). All 40 patients also underwent magnetic resonance angiography and T2-weighted imaging. Seventy-five did not meet inclusion criteria: in 45, magnetic resonance imaging was performed more than 24 hours after symptom onset; 12 did not have DWI; in 11 patients, symptoms resolved within 24 hours; 6 had hemorrhages; and 1 had a border zone infarct.

RESULTS

An acute lesion on DWI corresponding to the patient's symptoms was detected in all 40 patients, 16 (40%) of whom had detectable acute lesions on T2-weighted images. The lesions on DWI were larger in 11 of the 16 patients with positive T2-weighted images. Acute lesion volume did not correlate with NIHSS score (n = 40; rho = 0.30; P =.06, Spearman rank) also when DWI lesion volumes were divided by cause and territory.

CONCLUSIONS

Diffusion-weighted imaging is more effective than T2-weighted imaging in patients with acute posterior-circulation strokes. The DWI lesion volume did not significantly correlate with NIHSS score, suggesting that NIHSS is more weighted toward anterior-circulation stroke symptoms.

MRI features of intracerebral hemorrhage within 2 hours from symptom onset

BACKGROUND AND PURPOSE

MRI has been increasingly used in the evaluation of acute stroke patients. However, MRI must be able to detect early hemorrhage to be the only imaging screen used before treatment such as thrombolysis. Susceptibility-weighted imaging, an echo-planar T2* sequence, can show intracerebral hemorrhage (ICH) in patients imaged between 2.5 and 5 hours from symptom onset. It is unknown whether MRI can detect ICH earlier than 2.5 hours. We describe 5 patients with ICH who had MRI between 23 and 120 minutes from symptom onset and propose diagnostic patterns of evolution of hyperacute ICH on MRI.

METHODS

As part of our acute imaging protocol, all patients with acute stroke within 24 hours from symptom onset were imaged with a set of sequences that included susceptibility-weighted imaging, diffusion- and perfusion-weighted imaging, T1- and T2-weighted imaging, fluid-attenuated inversion recovery (FLAIR), and MR angiography using echo-planar techniques. Five patients with ICH had MRI between 23 and 120 minutes from the onset of symptoms.

RESULTS

ICH was identified in all patients. Distinctive patterns of hyperacute ICH and absence of signs of ischemic stroke were the hallmark features of this diagnosis. The hyperacute hematoma appears to be composed of 3 distinct areas: (1) center: isointense to hyperintense heterogeneous signal on susceptibility-weighted and T2-weighted imaging; (2) periphery: hypointense (susceptibility effect) on susceptibility-weighted and T2-weighted imaging; and (3) rim: hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging, representing vasogenic edema encasing the hematoma.

CONCLUSIONS

MRI is able to detect hyperacute ICH and show a pattern of evolution of the hematoma within 2 hours from the onset of symptoms.

Electromyographic Record of Classical Conditioning of Eye Withdrawal in the Crab

Classical (Pavlovian) conditioning of the eye withdrawal reflex of the green crab, Carcinus maenas, was studied by recording electromyograms (EMGs) from the main abductor muscle of the eye (19a). The EMG record was a reliable indicator of the response, and it was always correlated with physical movement of the eye, whether evoked by the unconditioned stimulus (a puff of air to the eye), or by the conditioned stimulus (a mild vibration of the carapace). The EMG was used to study the acquisition of conditioned responses in animals with an immobilized eye. Six of eight experimental animals developed responses to the conditioned stimulus in a manner similar to that for animals with freely moving eyes; unpaired controls showed few responses. The results indicate that eye movement is not required for learning. Behavioral tests after conditioning and after the eyes had been freed supported this conclusion. The results exclude theories of classical conditioning of eye withdrawal that invoke a role for stimuli due to eye movement (such as a change in visual field).