American Heart Association


Responsiveness after Hemorrhagic Stroke – Role of the Frontal Networks

Rizwan Kalani, MD

Mikell CB, Banks GP, Frey HP, Youngerman BE, Nelp TB, Karas PJ, et al. Frontal Networks Associated With Command Following After Hemorrhagic Stroke. Stroke. 2014

We often assess level of arousal by a patient’s ability to follow commands. In this study, Mikell et al evaluated which brain structures are necessary to follow commands in the setting of acute intracerebral hemorrhage (ICH) or subarachnoid hemorrhage (SAH) using a multimodality approach – a combination of structural and functional MRI (fMRI) as well as continuous EEG monitoring.

Data from 25 patients with spontaneous ICH or SAH that completed all components of the multi-modality testing were analyzed from a prospective, single-center database. 9 patients (36%) were unresponsive (unable to follow simple, 1-step commands) and 16 were awake at time of testing. Structural injury to the pons, midbrain, and thalamus was initially evaluated (by lesion volume quantification) using structural MRI. Resting state fMRI was then used to identify which brain networks were disrupted in the unresponsive patients compared to those who were awake. The relationship between the default mode network (DMN – the brain regions active when a person is awake and at rest) and the task-positive network (TPN – areas responding to attention-demanding tasks) were evaluated. Lastly, continuous EEG was used to confirm changes in functional connectivity seen.

There was no significant difference between the hemorrhage sizes of the unresponsive and awake patients. 6 functional networks were impaired in unresponsive patients by fMRI – these were located in the premotor, dorsal anterior cingulate, and supplementary motor areas. Connectivity between the DMN and right orbitofrontal cortex was decreased in unresponsive patients. Interestingly, new connections between the TPN and DMN were seen in unresponsive patients that were not seen in those who were awake. These findings were supported by EEG coherence data.

This manuscript suggests that disruption of frontal network connectivity (instead of the actual structural injury) accounts for unresponsiveness in the setting of ICH/SAH. It supports the idea that altered connectivity to (rather than within) the DMN is lost in an unresponsive state. Future studies will need to evaluate the mechanisms by which these network connectivity changes occur and how each individual network involved affects consciousness. The principal limitations of this study are the small number of patients included and inability to evaluate the effect of intracranial pressure on the findings.

By |December 10th, 2014|prognosis|0 Comments

Ischemia on CT is Predictive of Recurrent Stroke within 90 days for TIA/non-disabling Stroke Patients

Duy Le, MD

Wasserman JK, Perry JJ, Sivilotti MLA, Sutherland J, Worster A, Émond M, et al. Computed Tomography Identifies Patients at High Risk for Stroke After Transient Ischemic Attack/Nondisabling Stroke: Prospective, Multicenter Cohort Study. Stroke. 2014

Wasserman et al evaluate the predictive value of CT findings and risk of stroke. Specifically, they evaluate 2028 patients who presented to the hospital within 48 hours of symptoms, who had either a TIA or non-disabling stroke, receiving a scan within 24 hours. Head CT’s were evaluated by local neuro-radiologist as either being present or absent for evidence of acute ischemia, chronic ischemia and microagniopathy. Do these aforementioned patients with recent TIA or non-disabling stroke predict a higher likelihood of stroke in the forthcoming days? Wasserman et al answer: Yes! Stroke risk at 90 days was greater if baseline CT showed acute ischemia alone (10.6%; p = 0.002), acute + chronic ischemia (17.4%; p = 0.007), acute ischemia + microangiopathy (17.6%; p=0.019), or acute + chronic + microangiopathy (25.0%; p =0.029). The average age of patient’s was 67.9 +/- 14.5. 

Limitations of this study include the fact that only CT’s were used. CT’s are known to be less sensitive at detecting ischemia as compared to MRI’s. However some may argue that this models real world practical evaluation of strokes in the acute and early sub-acute strokes. A second limitation is that there was no distinction made between symptomatic and non-symptomatic acute lesions on head CT. Although acute ischemia seen on imaging in those with TIA symptoms or non-disabling stroke was shown to have higher risk of repeat ischemic event, from the data, we are unable to determine if patient’s new event was secondary to a new stroke or progression of the original stroke. This potentially may skew the data.

This study nonetheless, does show that imaging is useful in predicting future stroke in 90 days. Some may argue that imaging used as single parameter in this clinical setting may not be too useful. However, if used in conjunction with the ABCD2 score (as is seen in the new ABCD2I score), there may be clinical application. As with the ABCD2 score which stratifies risk of an immediate stroke, using imaging as a stroke risk marker will act to dictate management. Should a patient be admitted for expedited stroke work up inpatient, or can the patient have an outpatient work up? For those who mull over this question, imaging can act as an additional data point. It does seem intuitive otherwise that having a prior stroke would increase the risk of a subsequent stroke. However, now we can quantify that risk within 90 days and specify that to imaging findings.

By |December 5th, 2014|prognosis|0 Comments

Back Again: Hospital Readmissions after Stroke

Mark L. McAllister, MD

Evaluating an acute ischemic stroke patient in the inpatient setting, our concerns are often focused on determination of stroke etiology and secondary prevention measures, evaluating and treating early complications, and preparing patients for rehabilitation. What happens after the patient leaves the hospital is often a secondary concern. Readmission to the hospital is a common and deleterious outcome for many stroke patients.

The authors here investigated the rates of readmission among stroke patients in Dijon, France. Of 519 patients with first time stroke who survived initial hospitalization, 32% had a hospitalization in the first year after their discharge. The leading cause of admission was neurologic complaints, with stroke or TIA being the most frequent in that category. Unsurprisingly, patients who were older, had more comorbidities, and more severe initial strokes were most likely to have readmission in the year following stroke.

What is not clear in this study is what proportion of hospitalizations were due to preventable causes, and especially causes that were preventable based on actions taking place during the acute hospitalization for stroke. Readmission adversely affects patients’ general level of health and independence, emphasizing the need to minimize preventable readmissions. Finally, the correlation with initial stroke severity and rehospitalization further underscores the need for aggressive primary prevention measures in stroke to avoid these patients’ initial hospitalization.  

By |November 25th, 2014|prognosis|0 Comments

Broken Cookie Cutter: The Natural History of Unruptured Intradural Fusiform Aneurysms

Vikas Pandey, MD

Fusiform intracranial aneurysms are an entity that are not well studied, mainly due to the fact that fusiform aneursysms are rarer compared to saccular ones. The concept that the etiology of fusiform aneurysms is multifold leads to questions whether the approach to treat these types of aneuryms should be different based on specific aneurysmal characteristics as well as parts of the patient’s medical history. The authors headed by the interventional neuroradiology group from Toronto challenged the idea that treating fusiform intradural aneurysms carries a poor prognosis, an idea that has been ingrained due to poor prognosis of previously studied populations of veretebrobasilar fusiform aneurysms, and proposed that the natural histories of the different etiologies of fusiform aneurysms may be different.

The author conducted a retrospective study of patients seen between a 13 year period at Toronto Western Hospital cerebrovascular clinic and looked at 121 patients with unruptured intradural aneurysmal dilatation of >50% of the vessel wall circumference. Patients that were excluded were those with diameter >2.5 cm (these have a known poor natural history) and those with entirely extradural aneurysms. The aneurysms were categorized into those that were related to atherosclerosis and those that weren’t based on imaging criteria such as presence of eccentric, calcified plaques present within the aneurysms, as well as with supporting criteria based on risk factors for atherosclerosis (25 out of 121 put into this group). The groups were followed for 193 and 97 person-years for the non-atherosclerotic and atherosclerotic groups respectively. Results showed that the mortality in the atherosclerotic group was higher (5.2%/year vs 0.51%/year) and they had a higher aneurysm progression risk (12%/year vs 1.6%/year compared to the non-atherosclerotic counterparts.

The results provide an interesting dimension to treatment algorithms for fusiform aneurysms. The common sense risk factors such as a size and symptomatic presentation are not to be overshadowed, but looking into aspects of the pathophysiology of aneurysms which may appear similar on initial radiographic studies is an idea that should be applied to all areas of medicine. The authors bring up the very valid point that atherosclerotic aneurysms and non-atherosclerotic fusiform aneurysms should be thought of as entirely different disease entities. “Cookie cutter” medicine is very hard, especially in the field of stroke neurology and the authors provide us with an excellent example of this.


By |September 30th, 2014|prognosis|0 Comments

Time is Brain, again and again!

Chirantan Banerjee, MD

Muchada M, Rodriguez-Luna D, Pagola J, Flores A, Sanjuan E, Meler P, et al. Impact of Time to Treatment on Tissue-Type Plasminogen Activator–Induced Recanalization in Acute Ischemic Stroke. Stroke. 2014

The importance of time in hyperacute stroke care cannot be emphasized enough. In the NINDS tPA trial, the odds of a good functional outcome with IV tPA dropped from 2.6 if given between 0 – 90 min to 1.2 when given 271 – 360 min. Similarly, the NNT increased from 4.5 to 21.4. In the IMS-III trial, one of the major messages that emerged from the data was again that delays in time to angiographic reperfusion lead to a decreased likelihood of good clinical outcome in patients after moderate to severe stroke. With every step we take towards advancing acute stroke care, the importance of time to reperfusion keeps coming up again and again.

Now that the effect of time on functional outcome has been established, one interesting question that I have always had is that does delay in tPA delivery fail to improve outcomes with time because the brain tissue is not salvageable anymore, or that its efficacy to recanalize suffers as the clot matures, or a combination of the two. Muchada et al in the current issue of Stroke aimed to assess the influence of time on tPA induced recanalization in acute stroke patients. 508 consecutive acute stroke patients with proven MCA occlusions by TCD and who received IV tPA up to 4.5 hours, as well as ~6% who received tPA between 4.5 – 6 hours (selected by penumbral imaging) were included. Mean time to treatment was 171 min over the 7 year study period. TCD was repeated 1 hour post tPA. Any improvement in the TCD signal was considered to indicate recanalization. There was no linear association between time-to-treatment and recanalization. However, when converted to sequential 30 min time-to-treatment windows, as well as when dichotomized to <=270 min or >270 min, recanalization was seen to decrease with time. Several findings in the study corroborate with prior data. 

Overall recanalization rate of 36% is consistent with 30-40% previously reported. Also, higher NIHSS score, hyperglycemia, older age and female sex were again seen to decrease chance of recanalization.  Proximal MCA occlusions had a trend towards lower recanalization rate, especially after the first 90 min, in synergy with previous reports.  Distal occlusions had a recanalization rate ~30% regardless of time. The main limitation of the study is the measurement bias associated with use of TCD to assess vessel status. Also, the fact that only 6% patients received tPA >270 minutes affects the distribution of data. Some variables such as pre-treatment ASPECTS which have been previously shown to affect recanalization status were not included in the model.
This study again emphasizes the importance of time in acute stroke care, and finds poor recanalization outcomes beyond 270 min for proximal MCA occlusions. The authors argue that IV thrombolysis may be insufficient beyond this window, and more aggressive therapies should be explored. The critical question is, would it even matter if you do recanalize the occluded vessel at that point, or has the ship sunk already! 
By |August 26th, 2014|prognosis|0 Comments