EEG electrode localization with 3D iPhone scanning using point-cloud electrode selection (PC-ES).

Objective.Electroencephalography source imaging (ESI) is a valuable tool in clinical evaluation for epilepsy patients but is underutilized in part due to sensitivity to anatomical modeling errors. Accurate localization of scalp electrodes is instrumental to ESI, but existing localization devices are expensive and not portable. As a result, electrode localization challenges further impede access to ESI, particularly in inpatient and intensive care settings.Approach.To address this challenge, we present a portable and affordable electrode digitization method using the 3D scanning feature in modern iPhone models. This technique combines iPhone scanning with semi-automated image processing using point-cloud electrode selection (PC-ES), a custom MATLAB desktop application. We compare iPhone electrode localization to state-of-the-art photogrammetry technology in a human study with over 6000 electrodes labeled using each method. We also characterize the performance of PC-ES with respect to head location and examine the relative impact of different algorithm parameters.Main Results.The median electrode position variation across reviewers was 1.50 mm for PC-ES scanning and 0.53 mm for photogrammetry, and the average median distance between PC-ES and photogrammetry electrodes was 3.4 mm. These metrics demonstrate comparable performance of iPhone/PC-ES scanning to currently available technology and sufficient accuracy for ESI.Significance.Low cost, portable electrode localization using iPhone scanning removes barriers to ESI in inpatient, outpatient, and remote care settings. While PC-ES has current limitations in user bias and processing time, we anticipate these will improve with software automation techniques as well as future developments in iPhone 3D scanning technology.

Carotid endarterectomy should not be based on consensus statement duplex velocity criteria.

OBJECTIVE: Randomized trials support carotid endarterectomy (CEA) in asymptomatic patients with ≥60% internal carotid artery (ICA) stenosis. The widely referenced Society for Radiologists in Ultrasound Consensus Statement on carotid duplex ultrasound (CDUS) imaging indicates that an ICA peak systolic velocity (PSV) ≥230 cm/s corresponds to a ≥70% ICA stenosis, leading to the potential conclusion that asymptomatic patients with an ICA PSV ≥230 cm/s would benefit from CEA. Our goal was to determine the natural history stroke risk of asymptomatic patients who might have undergone CEA based on consensus statement PSV of ≥230 cm/s but instead were treated medically based on more conservative CDUS imaging criteria. METHODS: All patients who underwent CDUS imaging at our institution during 2009 were retrospectively reviewed. The year 2009 was chosen to ensure extended follow-up. Asymptomatic patients were included if their ICA PSV was ≥230 cm/s but less than what our laboratory considers a ≥80% stenosis by CDUS imaging (PSV ≥430 cm/s, end-diastolic velocity ≥151 cm/s, or ICA/common carotid artery PSV ratio ≥7.5). Study end points included freedom from transient ischemic attack (TIA), freedom from any stroke, freedom from carotid-etiology stroke, and freedom from revascularization. RESULTS: Criteria for review were met by 327 patients. Mean follow-up was 4.3 years, with 85% of patients having >3-year follow-up. Four unheralded strokes occurred during follow-up at <1, 17, 25, and 30 months that were potentially attributable to the index carotid artery. Ipsilateral TIA occurred in 17 patients. An additional 12 strokes occurred that appeared unrelated to ipsilateral carotid disease, including hemorrhagic events, contralateral, and cerebellar strokes. Revascularization was undertaken in 59 patients, 1 for stroke, 12 for TIA, and 46 for asymptomatic disease. Actuarial freedom from carotid-etiology stroke was 99.7%, 98.4%, and 98.4% at 1, 3, and 5 years, respectively. Freedom from TIA was 98%, 96%, and 95%, freedom from any stroke was 99%, 96%, and 93%, and freedom from revascularization was 95%, 86%, and 81% at 1, 3, and 5 years, respectively. CONCLUSIONS: Patients with intermediate asymptomatic carotid stenosis (ICA PSV 230-429 cm/s) do well with medical therapy when carefully monitored and intervened upon using conservative CDUS criteria. Furthermore, a substantial number of patients would undergo unnecessary CEA if consensus statement CDUS thresholds are used to recommend surgery. Current velocity threshold recommendations should be re-evaluated, with potentially important implications for upcoming clinical trials.

Risk of stroke after chiropractic spinal manipulation in medicare B beneficiaries aged 66 to 99 years with neck pain.

OBJECTIVE: The purpose of this study was to quantify risk of stroke after chiropractic spinal manipulation, as compared to evaluation by a primary care physician, for Medicare beneficiaries aged 66 to 99 years with neck pain. METHODS: This is a retrospective cohort analysis of a 100% sample of annualized Medicare claims data on 1 157 475 beneficiaries aged 66 to 99 years with an office visit to either a chiropractor or primary care physician for neck pain. We compared hazard of vertebrobasilar stroke and any stroke at 7 and 30 days after office visit using a Cox proportional hazards model. We used direct adjusted survival curves to estimate cumulative probability of stroke up to 30 days for the 2 cohorts. RESULTS: The proportion of subjects with stroke of any type in the chiropractic cohort was 1.2 per 1000 at 7 days and 5.1 per 1000 at 30 days. In the primary care cohort, the proportion of subjects with stroke of any type was 1.4 per 1000 at 7 days and 2.8 per 1000 at 30 days. In the chiropractic cohort, the adjusted risk of stroke was significantly lower at 7 days as compared to the primary care cohort (hazard ratio, 0.39; 95% confidence interval, 0.33-0.45), but at 30 days, a slight elevation in risk was observed for the chiropractic cohort (hazard ratio, 1.10; 95% confidence interval, 1.01-1.19). CONCLUSIONS: Among Medicare B beneficiaries aged 66 to 99 years with neck pain, incidence of vertebrobasilar stroke was extremely low. Small differences in risk between patients who saw a chiropractor and those who saw a primary care physician are probably not clinically significant.

Interhospital helicopter transport for stroke.

INTRODUCTION: The safety, cost efficacy, and time-to-treatment benefit of air transport of stroke patients have been acknowledged. We describe stroke patients transported to our facility by helicopter emergency medical services (HEMS) from a large rural area and compare 2 consecutive 3-year periods. METHODS: A retrospective chart review was conducted of all patients transferred by HEMS to our facility over 6 years. Data collected included patient demographics, pretransport imaging interpretation, final diagnosis, treatment, and outcomes. Trends between period 1 (January 1, 2003'December 31, 2005) and period 2 (January 1, 2006'December 31, 2008) were examined. RESULTS: A total of 347 acute stroke patients were transported by HEMS to our facility. The final diagnosis was intracerebral hemorrhage in 44%, subarachnoid hemorrhage in 24%, subdural hematoma in 14%, ischemic stroke or transient ischemic attack in 9%, and a nonstroke diagnosis in 7% of patients. Conventional cerebral angiography was performed in 28% of patients, and neurosurgical intervention, hematoma evacuation, or aneurysm clipping was performed in 32%. A final diagnosis of ischemic stroke or transient ischemic attack increased 3 times (4% vs. 12%, P < .05) from period 1 to 2. There was also a significant increase in the number of patients receiving intravenous tissue plasminogen activator before transport (0% vs. 3%, P < .01). CONCLUSIONS: The majority of our patients transported by HEMS for the management of acute stroke undergo urgent specialized diagnostics or interventions. This supports the role of interhospital HEMS transport in extending access to care in rural communities.

Critical care of patients with acute ischemic and hemorrhagic stroke: update on recent evidence and international guidelines.

Patients with acute ischemic and hemorrhagic stroke are often managed in a critical care setting. Disturbances in BP, body temperature, and serum glucose are commonly observed but their management remains controversial. The reversal of antithrombotic medications and prognostication are especially challenging for intracerebral hemorrhages. This review highlights recent clinical trials and the recommendations found in international guidelines relevant to these topics. We aim to provide a practical and brief, yet current, review of these more problematic areas of stroke care.

A fatal case of postpartum cerebral angiopathy with literature review.

INTRODUCTION: Postpartum cerebral angiopathy (PCA) is a rare and pathophysiologically ill-characterized cerebral vasoconstriction syndrome, occurring within 30 days of a usually uncomplicated pregnancy and delivery. Its onset has been associated with the use of vasoactive medications, particularly ergot alkaloids. Other cases have occurred in the absence of these medications, prompting conjecture into possible overlap between PCA and other conditions known to cause cerebral vasoconstriction, including primary angiitis of the central nervous system and postpartum eclampsia. The vast majority of cases follow a relatively benign course; however, a fatal case has been reported. Histopathologic findings in PCA, so far limited to the fatal case and two more recent biopsies, have been nonspecific. OBJECTIVE: Here we present a second fatal case of PCA, including pre- and post-mortem histopathologic analysis. We also include a review of all PCA cases reported in the English literature. METHODS: Criteria for the clinical diagnosis of PCA are proposed and used to select case reports from the medical literature. Data pertaining to patient characteristics, clinical symptomatology, cerebral imaging findings, and clinical outcomes are compared between cases associated with the postpartum use of vasoactive medications and spontaneous cases. CONCLUSIONS: We conclude that histopathologic findings in PCA are nonspecific and secondary to ischemic brain injury. Functional vasoconstriction is the most likely primary pathophysiologic process in PCA. The etiology in cases associated with medications may be due to idiosyncratic reactions to these agents. Significant overlap in symptomatology and clinical features exists between spontaneous cases and late postpartum eclampsia.

"Triple-H" therapy for cerebral vasospasm following subarachnoid hemorrhage.

The combination of induced hypertension, hypervolemia, and hemodilution (triple-H therapy) is often utilized to prevent and treat cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Although this paradigm has gained widespread acceptance over the past 20 years, the efficacy of triple-H therapy and its precise role in the management of the acute phase of SAH remains uncertain. In addition, triple-H therapy may carry significant medical morbidity, including pulmonary edema, myocardial ischemia, hyponatremia, renal medullary washout, indwelling catheter-related complications, cerebral hemorrhage, and cerebral edema. This review examines the evidence underlying the implementation of triple-H therapy, and makes practical recommendations for the use of this therapy in patients with aneurysmal SAH.

Hemispheric asymmetry in a dissociation between the visuomotor and visuoperceptual streams.

We have explored the level of interaction between the putative visuoperceptual (VP) and visuomotor (VM) processing streams within each cerebral hemisphere. Six patients with unilateral brain lesions and 26 intact-brain participants were tested. We presented three-dimensional versions of the Mueller-Lyer illusion separately to the left and to the right hemifields of each participant. In one condition, the participant grasped the central shaft of the illusion object between the thumb and forefinger (visuomotor task). In the other, the participant estimated the size of the shaft using the same fingers (visuoperceptual task). We calculated the magnitude of the illusion in each task for each hemifield. Intact-brain participants had a significantly larger illusion in estimation than in grasping in both hemifields. The two patients with right-hemisphere damage showed a large dissociation between grasping and estimation illusions, whereas the four patients with left-hemisphere damage showed no detectable dissociation. These results are consistent with the idea that the visuomotor and visuoperceptual streams are more dissociated in the left hemisphere than in the right.