The relationship between mean flow velocity and functional and neurologic parameters of ischemic stroke patients undergoing rehabilitation

Transcranial Doppler ultrasonography can predict inpatient rehabilitation functional outcome in patients with stroke

BACKGROUND

Despite advances in imaging techniques and treatment modalities, tools to predict recovery after stroke remain limited.

OBJECTIVE

To determine if transcranial Doppler (TCD) mean flow velocities were predictive of functional recovery following ischemic stroke.

METHODS

Data were collected from patients with stroke admitted to an academic tertiary care facility in the southeastern region of the United States between 2012 and 2019 who had a middle cerebral artery distribution ischemic stroke, TCD, and were discharged to our inpatient rehabilitation facility. Mean flow velocities were categorized as low (<40 cm/s), normal (40-80 cm/s), or high (>80 cm/s). Functional Independence Measure (FIM) scores were collected on admission to and discharge from inpatient rehabilitation. Multiple linear regression models were used to assess the differences in mean FIM score changes by categories of mean flow velocities.

RESULTS

We enrolled 57 patients, mean age 60 years, 73.7% male. Compared to the normal velocity group, those with abnormally low velocities had a significantly smaller change in their FIM score (adjusted β = -8.42; p = .01). Compared to the normal velocity group, those with abnormally high velocities experienced a greater change in FIM score, but this association was not statistically significant (beta = 1.12; p = .77).

CONCLUSIONS

In this limited population, we found that low mean flow velocity as measured by TCD ultrasonography after a middle cerebral artery stroke is associated with poorer functional recovery following inpatient rehabilitation. Our results suggest that the value of TCD ultrasonography as a tool to predict motor recovery after stroke warrants further investigation.

Effect of head-down tilt on clinical outcome and cerebral perfusion in ischemic stroke patients: A case series

Background

The effect of head position on stroke is not clear. The current study aimed to observe the effect of head-down tilt on acute ischemic stroke (AIS) patients with large vessel occlusion.

Methods

We observed the influence of head-down tilt position on clinical outcomes, myocardial enzymogram and N-terminal pro b-type Natriuretic Peptide in 4 AIS patients who suffered early neurological deterioration (END). Cerebral perfusion imaging was performed in 3 patients using arterial spin labeling.

Results

In series of AIS patients with END, head down tilt (-20°) prevented further neurological deterioration and improved clinical outcomes. An increase in cerebral blood flow was observed by arterial spin labeling after head down tilt treatment. No obvious adverse events occurred.

Conclusion

The case series suggest that head-down tilt may improve clinical outcome in AIS patients through increasing the cerebral perfusion with no obvious adverse events. The finding needs to be confirmed in future clinical trials.

Transcranial Color Coded Duplex Sonography Findings in Stroke Patients Undergoing Rehabilitation: An Observational Study

Background  Transcranial color-coded duplex sonography (TCCD) provides information on intracranial blood flow status in stroke patients and can predict rehabilitation outcomes. Objective  This study aimed to assess middle cerebral artery (MCA) parameters using TCCD in MCA territory stroke patients admitted for rehabilitation and correlate with clinical outcome measures. Materials and Methods  Patients aged 18 to 65 years with a first MCA territory stroke, within 6 months of onset were recruited. The clinical outcome scales and TCCD parameters were assessed at both admission and discharge. The scales used were the Scandinavian stroke scale (SSS), Barthel Index (BI), modified Rankin Scale (mRS), Fugl-Meyer upper extremity scale (FMA-UE), modified motor assessment scale (mMAS) scores. TCCD parameters measured were MCA peak systolic, end diastolic, mean flow velocities (MFV), and index of symmetry (SI) and were correlated with clinical scores. Results  Fourteen patients were recruited with median age of 56.5 years, median duration of stroke was 42.5 days. Mean flow velocities of affected and unaffected MCA were 46.2 and 50.7 cm/s, respectively. Flow velocities and SI did not change between the two assessments. There was significant improvement in clinical outcome scores at discharge. Significant correlation was observed for patient group with SI > 0.9 at admission with FMA-UE, SSS, and BI scores at discharge ( p  < 0.05). Conclusion  Flow velocity parameters did not change during in-patient rehabilitation. Patients with symmetric flow at admission had improved clinical outcomes measure scores at discharge. Thus SI can predict rehabilitation outcomes in stroke survivors.

Statistical analysis plan for the Head Position in Stroke Trial (HeadPoST): An international cluster cross-over randomized trial

Background There is evidence to indicate that the lying flat head position increases cerebral blood flow and oxygenation in patients with acute ischemic stroke, but how these physiological effects translate into clinical outcomes is uncertain. The Head Position in Stroke Trial aims to determine the comparative effectiveness of lying flat (0°) compared to sitting up (≥30°) head positioning, initiated within 24 h of hospital admission for patients with acute stroke. Design An international, pragmatic, cluster-randomized, crossover, open, blinded outcome assessed clinical trial. Each hospital with an established acute stroke unit (cluster) site was required to recruit up to 140 consecutive cases of acute stroke (one phase of head positioning before immediately crossing over to the other phase of head positioning), including both acute ischemic stroke and intracerebral hemorrhage, in each randomized head position as a 'business as usual' policy. Objective To outline in detail the predetermined statistical analysis plan for the study. Methods All accumulated data will be reviewed and formally assessed. Information regarding baseline characteristics of patients, their process of care and management will be outlined, and for each item, statistically relevant descriptive elements will be described. For the trial outcomes, the most appropriate statistical comparisons are described. Results A statistical analysis plan was developed that is transparent, verifiable, and predetermined before completion of data collection. Conclusions We developed a predetermined statistical analysis plan for Head Position in Stroke Trial to avoid analysis bias arising from prior knowledge of the findings, in order to reliably quantify the benefits and harms of lying flat versus sitting up early after the onset of acute stroke. Trial registration ClinicalTrials.gov identifier NCT02162017; ANZCTR identifier ACTRN12614000483651.

Head position and cerebral blood flow in acute ischemic stroke patients: Protocol for the pilot phase, cluster randomized, Head Position in Acute Ischemic Stroke Trial (HeadPoST pilot)

Rationale

Few proven interventions exist for acute ischemic stroke (AIS), and most are expensive and restricted in applicability. Lying flat ‘head down’ positioning of AIS patients has been shown to increase by as much as 20%, mean cerebral blood flow velocities (CBFV) measured by transcranial Doppler (TCD) but whether this translates into clinical improvement is uncertain.

Aim

To determine if the lying flat position increases mean CBFV in the affected territory as compared to the sitting up position in AIS patients.

Methods and design

Head Position in Acute Ischemic Stroke Trial (HeadPoST pilot) is a cluster randomized (clusters being months), assessor-blinded end-point, phase IIb trial, where consecutive adults with anterior circulation AIS within 12 h of symptom onset are positioned to a randomized position for 48 h with TCD performed serially.

Study outcomes

Primary outcome is mean CBFV on TCD at 1 and 24 h after positioning. Secondary outcomes include: serious adverse events, neurological impairment at seven days, and death and disability at 90 days.

Sample size estimates

Assuming an increase of 8.3 (SD 11.4) cm/s in average of mean CBFV when tilted from 30° to 0°, 46 clusters are required (92 patients in total) to detect a 20% increase of mean CBFV with 90% power and 5% level of significance.

Conclusion

HeadPoST pilot is a cluster randomized multicenter clinical trial investigating the effect of head positioning on mean CBFV in anterior circulation AIS.

The Effects of Acupuncture on Cerebral Blood Flow in Post-Stroke Patients: A Randomized Controlled Trial

BACKGROUND/OBJECTIVE

Stroke is a major cause of disability and death in the Western world. Studies have shown a direct relationship between specific mental and motor activity and changes in cerebral blood flow. Acupuncture is often used in post-stroke patients, but there is a lack of sham-controlled studies evaluating the effects of acupuncture on cerebral blood flow following a stroke. This pilot concept-assessment study sought to evaluate the effects of true acupuncture on cerebral blood flow velocity compared with sham acupuncture and lay a foundation for future work in this field.

METHODS

Seventeen inpatients (age range, 44-79 years) 1-3 months post-stroke were allocated to acupuncture at true acupuncture (TA) points or at sham acupuncture (SA) points. The treatment was 20 minutes long. Transcranial Doppler ultrasonography was used to measure mean flow velocity (MFV) and peak flow velocity (PFV) at both healthy and damaged hemispheres before (T0), in the middle of (T15), and 5 minutes after (T25) treatment. Blood pressure was measured at T0 and T25.

RESULTS

A statistically significant (p < 0.04) MFV increase in both hemispheres was found during and after TA; this increase was higher than that seen with SA (p < 0.035). Acupuncture had no significant effect on PFV. Systolic blood pressure significantly decreased after acupuncture (p < 0.005) in a similar manner for both TA and SA. National Institutes of Health Stroke Scale score was negatively correlated with MFV at T15 (r = -0.825; p < 0.05).

CONCLUSION

This pilot study showed a significant influence on cerebral blood flow velocity by TA. This study lays a foundation for larger-scale studies that may prove acupuncture to be a useful tool for cerebral blood flow enhancement during post-stroke rehabilitation.

Head Position in Stroke Trial (HeadPoST)--sitting-up vs lying-flat positioning of patients with acute stroke: study protocol for a cluster randomised controlled trial

Background

Positioning a patient lying-flat in the acute phase of ischaemic stroke may improve recovery and reduce disability, but such a possibility has not been formally tested in a randomised trial. We therefore initiated the Head Position in Stroke Trial (HeadPoST) to determine the effects of lying-flat (0°) compared with sitting-up (≥30°) head positioning in the first 24 hours of hospital admission for patients with acute stroke.

Methods/Design

We plan to conduct an international, cluster randomised, crossover, open, blinded outcome-assessed clinical trial involving 140 study hospitals (clusters) with established acute stroke care programs. Each hospital will be randomly assigned to sequential policies of lying-flat (0°) or sitting-up (≥30°) head position as a ‘business as usual’ stroke care policy during the first 24 hours of admittance. Each hospital is required to recruit 60 consecutive patients with acute ischaemic stroke (AIS), and all patients with acute intracerebral haemorrhage (ICH) (an estimated average of 10), in the first randomised head position policy before crossing over to the second head position policy with a similar recruitment target. After collection of in-hospital clinical and management data and 7-day outcomes, central trained blinded assessors will conduct a telephone disability assessment with the modified Rankin Scale at 90 days. The primary outcome for analysis is a shift (defined as improvement) in death or disability on this scale. For a cluster size of 60 patients with AIS per intervention and with various assumptions including an intracluster correlation coefficient of 0.03, a sample size of 16,800 patients at 140 centres will provide 90 % power (α 0.05) to detect at least a 16 % relative improvement (shift) in an ordinal logistic regression analysis of the primary outcome. The treatment effect will also be assessed in all patients with ICH who are recruited during each treatment study period.

Discussion

HeadPoST is a large international clinical trial in which we will rigorously evaluate the effects of different head positioning in patients with acute stroke.

Trial registration

ClinicalTrials.gov identifier: NCT02162017 (date of registration: 27 April 2014); ANZCTR identifier: ACTRN12614000483651 (date of registration: 9 May 2014). Protocol version and date: version 2.2, 19 June 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-0767-1) contains supplementary material, which is available to authorized users.

Constraint-induced movement therapy alters cerebral blood flow in subacute post-stroke patients

We attempted to evaluate patterns of hemispheric activation, according to cerebral blood flow changes, in post-stroke patients during motor tasks with and without arm restriction. Bilateral continuous middle cerebral artery monitoring of 6 healthy subjects (control group) and 28 post-stroke patients by transcranial Doppler sonography was executed while performing three simple motor tasks using the paretic or nondominant (in controls) hand: ball grasping, pegs insertion, and "eating" with a spoon. The nonaffected or dominant (in controls) arm was free and thereafter restricted. Mean blood flow velocity and flow velocity changes during the tests were estimated. No significant mean blood flow velocity changes were found in the healthy subjects. Significant elevation of mean blood flow velocity in damaged middle cerebral artery was recorded in post-stroke patients after restricting the undamaged hand. This may explain the positive effect of constraint-induced movement therapy on upper limb function.

Imaging of perfusion, angiogenesis, and tissue elasticity after stroke

Blood flow interruption in a cerebral artery causes brain ischemia and induces dramatic changes of perfusion and metabolism in the corresponding territory. We performed in parallel positron emission tomography (PET) with [(15)O]H(2)O, single photon emission computed tomography (SPECT) with [(99m)Tc]hexamethylpropylene-amino-oxime ([(99m)Tc]HMPAO) and ultrasonic ultrafast shear wave imaging (SWI) during, immediately after, and 1, 2, 4, and 7 days after middle cerebral artery occlusion (MCAO) in rats. Positron emission tomography and SPECT showed initial hypoperfusion followed by recovery at immediate reperfusion, hypoperfusion at day 1, and hyperperfusion at days 4 to 7. Hyperperfusion interested the whole brain, including nonischemic areas. Immunohistochemical analysis indicated active angiogenesis at days 2 to 7, strongly suggestive that hyperperfusion was supported by an increase in microvessel density in both brain hemispheres after ischemia. The SWI detected elastic changes of cerebral tissue in the ischemic area as early as day 1 after MCAO appearing as a softening of cerebral tissue whose local internal elasticity decreased continuously from day 1 to 7. Taken together, these results suggest that hyperperfusion after cerebral ischemia is due to formation of neovessels, and indicate that brain softening is an early and continuous process. The SWI is a promising novel imaging method for monitoring the evolution of cerebral ischemia over time in animals.

Positron emission tomograghy with [¹³N]ammonia evidences long-term cerebral hyperperfusion after 2h-transient focal ischemia

BACKGROUND AND PURPOSE

It is well known that after cerebral ischemia, brain suffers blood flow changes over time that have been correlated with inflammation, angiogenesis and functional recovery processes. Nevertheless, post-ischemic spatiotemporal changes of brain perfusion have not been fully investigated to date. Here we tested whether PET with [¹³N]ammonia would evidence the perfusion changes presented by different brain regions in an experimental model of brain ischemia.

EXPERIMENTAL PROCEDURES

Seven rats were subjected to a 2-h transient middle cerebral artery occlusion with reperfusion. PET studies were performed longitudinally using [¹³N]ammonia at 1, 3, 7, 14, 21 and 28 days after cerebral ischemia.

RESULTS

In vivo PET imaging showed a significant increase in [¹³N]ammonia uptake at 7 days after cerebral ischemia with respect to one day after the occlusion in the cerebral territory irrigated by the MCA in both the ischemic and contralateral hemispheres. This increase was followed by a return to control values at day 28 after ischemia onset. Brain regions located both inside and outside the primary infarct areas showed similar perfusion changes after cerebral ischemia.

CONCLUSIONS

[¹³N]ammonia shows hemodynamic changes after stroke involving hyperperfusion that might be related to angiogenesis and functional recovery. Long-term blood hyperperfusion is found both in ischemic and remote areas to infarction. These results may contribute to a better understanding of the evolution of cerebral ischemic lesion in animal models.

Mean flow velocity in the middle cerebral artery is associated with rehabilitation success in ischemic stroke patients

OBJECTIVE

To evaluate the association between mean flow velocity (MFV) in the middle cerebral artery (MCA) measured by using transcranial Doppler (TCD) and functional and neurologic impairment change during rehabilitation after acute stroke.

DESIGN

Cross-sectional observational study.

SETTING

Acute neurologic rehabilitation department.

PARTICIPANTS

Consecutive patients (N=67; 53 men, 14 women; mean ± SD age, 61.54±8.92y) referred to the rehabilitation center during the first 6 months of 2006 for a first ischemic stroke in the MCA area.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

All subjects were evaluated on admission and at discharge by using the National Institutes of Health Stroke Scale (NIHSS) and the FIM. TCD measurements of MFV of the ipsilateral and contralateral MCA were performed on admission (during the first 20 days after stroke) and a few days before discharge.

RESULTS

Contralateral MFV at admission was associated significantly with all indexes of functional rehabilitation success (FIM score at discharge [β=.169; P=.010], change in FIM score [β=.554; P=.010], relative improvement in FIM score [β=.783; P=.003]). No significant association was found between indexes of NIHSS change and ipsilateral or contralateral MFV.

CONCLUSIONS

Ipsilateral or contralateral MFV measured at admission did not change during the 2-month rehabilitation period. Our data showed a significant association between blood flow velocity in the contralateral MCA and functional rehabilitation parameters of patients after first ischemic stroke in the MCA area.

Transcranial doppler monitoring during language tasks in stroke patients with aphasia

PURPOSE

To investigate the pattern of hemispheric activation, according to cerebral blood flow changes, as measured by Transcranial Doppler Ultrasonography (TCD) during language tasks in stroke patients with aphasia.

METHOD

Prospective study investigating results of TCD monitoring during language naming and recognition tasks in ischemic stroke patients (n = 32) with and without aphasia and 5 control subjects.

RESULTS

Delta mean flow velocity (MFV) in the left Middle Cerebral Artery (MCA) was found to be much lower in aphasia patients as compared to healthy subjects. Negative statistical correlation was found between the improvement of language ability and the blood flow velocity parameters in the left hemisphere. Aphasia patients with good language ability showed much higher MFV in the right MCA during the first test. Left hemispheric blood flow velocity shift was found to be higher during speech tasks in the patients with poor language ability.

CONCLUSIONS

Our study suggests that the performance of language tasks in aphasia patients during early recovery after stroke is associated with relatively high right hemisphere activation. High blood flow velocity in the right MCA of aphasia patients was found to be a good prognostic sign for better language ability. Arterial blood flow that shifted towards the left hemisphere during speech tasks was associated with poor language ability.

Orthostatic hypotension and cerebral blood flow velocity in the rehabilitation of stroke patients

The objective of this study was to investigate the results of transcranial Doppler monitoring during tilt table tests in stroke patients with and without orthostatic hypotension. In stroke patients without orthostatic hypotension, the mean flow velocity was almost similar in both middle cerebral arteries and was stable during the test. In patients with orthostatic hypotension symptoms, a significant difference was found between the two hemispheres. Mean flow velocity in the damaged middle cerebral artery was lower in the supine position and stayed almost the same at 80 degrees standing. In the non-damaged middle cerebral artery, however, the mean flow velocity was much higher when supine and dropped in the standing position. These findings suggest that the appearance of orthostatic hypotension symptoms may be associated in post-stroke patients with decreased blood velocity in the damaged middle cerebral artery. Those patients are at a high risk of developing syncopal reactions and should be treated on the tilt table with caution, especially at the beginning of the rehabilitation.