Jongyeol Kim

Transcranial Doppler Velocities in a Large, Healthy Population

Transcranial Doppler (TCD) ultrasonography has been extensively used in the evaluation and management of patients with cerebrovascular disease since the clinical application was first described in 1982 by Aaslid and colleagues TCD is a painless, safe, and noninvasive diagnostic technique that measures blood flow velocity in various cerebral arteries. Numerous commercially available TCD devices are currently approved for use worldwide, and TCD is recognized to have an established clinical value for a variety of clinical indications and settings. Although many studies have reported normal values, there have been few recently, and none to include a large cohort of healthy subjects across age, race, and gender. As more objective, automated processes are being developed to assist with the performance and interpretation of TCD studies, and with the potential to easily compare results against a reference population, it is important to define stable normal values and variances across age, race, and gender, with clear understanding of variability of the measurements, as well as the yield from various anatomic segments.

Dynamic vascular analysis shows a hyperemic flow pattern in sickle cell disease.

Background. By the age of 20 years, 10% of sickle cell disease (SCD) patients have experienced a stroke. It is unclear if SCD stroke is due primarily to hemodynamic effects of intracranial stenosis, or metabolic failure from anemia. Transcranial Doppler ultrasound (TCD) identifies a SCD subgroup with high stroke risk, but high mean flow velocity (MFV) can be due to stenosis or high flow rate, as with metabolic hyperemia of severe anemia. Dynamic Vascular Analysis (DVA; New Health Sciences, Inc., Bethesda, MD) is a new way to analyze TCD data, with potential to separate structural from metabolic causes of high MFV.

Cardiac Arrhythmias and Abnormal Electrocardiograms After Acute Stroke

&NA; Cardiac arrhythmias and electrocardiogram (ECG) abnormalities occur frequently but are often underrecognized after strokes. Acute ischemic and hemorrhagic strokes in some particular area of brain can disrupt central autonomic control of the heart, precipitating cardiac arrhythmias, ECG abnormalities, myocardial injury and sometimes sudden death. Identification of high‐risk patients after acute stroke is important to arrange appropriate cardiac monitoring and effective management of arrhythmias, and to prevent cardiac morbidity and mortality. More studies are needed to better clarify pathogenesis, localization of areas associated with arrhythmias and practical management of arrhythmias and abnormal ECGs after acute stroke.

Pupil to limbus ratio: Introducing a simple objective measure using two-box method for measuring early anisocoria and progress of pupillary change in the ICU

Introduction: Measurement of static pupillary size in the ICU is of importance in cases of acutely expanding intracranial mass lesions. The inaccuracies with subjective assessment of pupillary size by medical personnel preclude its use in emergent neurological situations. Objective: To determine if the ratio of pupil to limbus diameter (PLD ratio) measured by a two-box method is a reliable measure of pupil size for detecting early anisocoria and measuring pupillary changes. Materials and Methods: The PLD ratio was defined as the ratio of the pupillary diameter measured at a para-horizontal axial plane with the limbus diameter measured at the same or parallel axial plane. A two-box method was used to estimate the diameters of imaged pupils. Eyes were imaged using an iPhone 4S cellphone camera. Background illumination was measured and kept constant. The pupils of a 78-year-old woman, who presented with a large intra-axial parenchymal hemorrhage, were imaged. The patient had left pupillary miosis in dark but not in bright light. After presenting this case along with the images of the pupillary examination, a group of 21 medical staff were asked several questions on the pupillary examination. Reliability of PLD ratio were assessed via standard error of mean (S.E.M) of PLD ratios for 3 different subjects each imaged under constant illumination and fixation but from different angles to the optical axis. Results: Analysis of questionnaire data together with PLD ratios revealed that ~ 14% and 10% of participants could estimate the pupillary size in darkness and bright light respectively but none were simultaneously accurate indicating that subjective assessment of pupillary size was unreliable. The approach towards a systematic pupillary examination was inconsistent among the participants. The PLD ratio was found to be a reliable measure of pupillary size with standard error of mean below 0.1 mm for the three subjects tested. Conclusion: Static pupillary sizes can be objectively and consistently evaluated using PLD ratios using a two-box method. PLD ratios are resistant, within limits, to changes in imaging angle or choice of para-horizontal axes for measurement.

Subacute Neurological Deterioration with Selective Axonal Injury in Patients with Acute Ischemic Stroke following Reperfusion of Middle Cerebral Artery Occlusion.

To date, the long-term effects of reperfusion on the salvaged brain tissues have not been addressed in the literature. We report 4 cases presenting subacute neurological deteriorations with selective axonal injury following reperfusion therapies for acute ischemic stroke. Our case series based on 4 patients showed common features distinct from those of early reperfusion injury in that (1) the neurological symptoms developed after 1–2 months of reperfusion therapies, (2) these symptoms were accompanied by the subcortical white matter changes on brain MRI, and (3) these findings were mostly reversible with time. This suggests that axons in the reperfused brain may be vulnerable to further neurological injury.

Effects of arm weight on gait performance in healthy subjects

Previous studies have investigated how additional arm weights affect gait. Although light weights (0.45u202fkg) seemed to elicit performance improvements in Parkinsonian patients, it was not studied how light weights affect gait parameters in healthy individuals. It is important to understand normal responses in a healthy population so that clinical effects might be better understood. Therefore, the purpose of this study was to investigate the effects of arm weights on arm swing amplitude, gait performance, and muscle activity in healthy people. Twenty-two subjects walked overground at their preferred speed under different weight carriage conditions (C1: no weight; C2: unilateral arm weight; C3: bilateral arm weights; C4: waist weights). Gait speed increased in C2 (pu202f=u202f0.018) and C4 (pu202f=u202f0.013) when compared with C1(C1: 1.21u202f±u202f0.08; C2: 1.25u202f±u202f0.11; C3: 1.24u202f±u202f0.11; C4: 1.25u202f±u202f0.11u202fm/s) with an increase in cadence during C2 (pu202f<u202f0.001), C3 (pu202f=u202f0.008), and C4 (pu202f<u202f0.001) (C1: 105.5u202f±u202f5.2; C2: 108.5u202f±u202f5.6; C3: 107.9u202f±u202f5.6; C4: 108.5u202f±u202f5.3 steps/min) and in tibialis anterior electromyographic activity on the unweighted side in C2 (pu202f=u202f0.048) (C1: 21.05u202f±u202f4.59; C2: 25.10u202f±u202f6.10; C3: 23.93u202f±u202f4.75; C4: 24.33u202f±u202f6.32u202fμV). The results indicate that an additional sensory input with the application of the weights may result in an overcompensation with the whole body and facilitate faster walking speed when applied on one arm or around the waist. The locations of the weights and amount of the weights may elicit different responses. Various strategies of adding weights should be further investigated as a potential intervention to improve performance in individuals with various gait impairments. Although there is evidence for benefits of this intervention in Parkinsonian patients, further study is warranted in other patient populations, such as stroke patients, who might benefit from this intervention to improve gait performance.

Translational Correlation: Migraine

Abstract Migraine is an episodic, unilateral or bilateral, moderate to severe throbbing headache, generally associated with nausea, vomiting, light sensitivity, or sound sensitivity. Migraine can be broadly divided into migraine with and without aura. There is no unified mechanism that can explain pathogenesis of migraine. The treatment for migraine consists of acute or abortive treatment and preventive treatment.

Does Doppler detection of asymptomatic embolization predict stroke risk in symptomatic carotid artery stenosis

Does Doppler detection of asymptomatic embolization predict stroke risk in symptomatic carotid artery stenosis?