ORCID Profile
0000-0001-5218-863X
Current Organisation
The University of Auckland
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Publisher: SAGE Publications
Date: 10-2017
Abstract: Background and Objective. The likelihood of regaining independent walking after stroke is of concern to patients and their families and influences hospital discharge planning. The objective of this study was to explore factors that could be combined in an algorithm for predicting whether and when a patient will walk independently after stroke. Methods. Adults with new lower limb weakness were recruited within 3 days of having a stroke. Clinical assessment, transcranial magnetic stimulation, and magnetic resonance imaging were completed 1 to 2 weeks poststroke. Classification and regression tree (CART) analysis was used to identify factors that predicted whether a patient achieved independent walking by 6 or 12 weeks, or remained dependent at 12 weeks. Results. We recruited 41 patients (24 women median age 72 years, range 43-96 years). The CART analysis results were used to create the Time to Walking Independently after STroke (TWIST) algorithm, which made accurate predictions for 95% of patients. Patients with a trunk control test score at 1 week walked independently within 6 weeks. Patients with a trunk control test score only achieved independent walking by 12 weeks if they also had hip extension strength of Medical Research Council grade 3 or more. Neurophysiological and neuroimaging measures did not predict independent walking after stroke. Conclusions. In this exploratory study, the TWIST algorithm accurately predicted whether and when an in idual patient walked independently after stroke using simple bedside measures 1 week poststroke. Further work is required to develop and validate this algorithm in a larger study.
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.BRAINRES.2016.11.004
Abstract: Transcranial magnetic stimulation (TMS) is used to examine corticospinal tract integrity after stroke, however, generating motor-evoked potentials (MEPs) in the lower limb (LL) can be difficult. Previous studies have used activation of the target leg to facilitate MEPs in the LL but this may not be possible after stroke due to hemiplegia. The dominance of the target limb may also be important, however the neurophysiological effects of LL dominance are not known. We investigated whether voluntary activation of the non-target leg combined with optimal TMS coil orientation increases corticomotor excitability in healthy adults, and whether limb dominance influences these results. TMS was delivered to induce a posterior-anterior (PA) and a medial-lateral (ML) cortical current in 22 healthy adults. MEPs were recorded in tibialis anterior (TA) with the participant at rest and when activating the non-target leg. We found that non-target leg activation increased corticomotor excitability in the target leg (reduced rest motor threshold (RMT) and MEP latency, and increased recruitment curve slope). ML cortical current also reduced RMT and MEP latency. The degree of footedness correlated with the degree of RMT asymmetry, with a PA but not ML cortical current direction. In summary, cross-facilitation by activating the non-target leg in a task requiring postural stabilisation and inducing ML current increase corticomotor excitability regardless of limb dominance. This protocol may have practical application in testing CST integrity after stroke when paretic limb thresholds are high, by increasing the likelihood of eliciting a MEP.
Publisher: SAGE Publications
Date: 18-05-2022
DOI: 10.1177/15459683221085287
Abstract: The likelihood of regaining independent walking after stroke influences rehabilitation and hospital discharge planning. This study aimed to develop and internally validate a tool to predict whether and when a patient will walk independently in the first 6 months post-stroke. Adults with stroke were recruited if they had new lower limb weakness and were unable to walk independently. Clinical assessments were completed one week post-stroke. The primary outcome was time post-stroke by which independent walking (Functional Ambulation Category score ≥ 4) was achieved. Cox hazard regression identified predictors for achieving independent walking by 4, 6, 9, 16, or 26 weeks post-stroke. The cut-off and weighting for each predictor was determined using β-coefficients. Predictors were assigned a score and summed for a final TWIST score. The probability of achieving independent walking at each time point for each TWIST score was calculated. We included 93 participants (36 women, median age 71 years). Age 80 years, knee extension strength Medical Research Council grade ≥ 3/5, and Berg Balance Test 6, 6 to 15, or ≥ 16/56, predicted independent walking and were combined to form the TWIST prediction tool. The TWIST prediction tool was at least 83% accurate for all time points. The TWIST tool combines routine bedside tests at one week post-stroke to accurately predict the probability of an in idual patient achieving independent walking by 4, 6, 9, 16, or 26 weeks post-stroke. If externally validated, the TWIST prediction tool may benefit patients and clinicians by informing rehabilitation decisions and discharge planning.
Publisher: Public Library of Science (PLoS)
Date: 22-03-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2017
DOI: 10.1161/STROKEAHA.116.016478
Abstract: In people with preserved corticospinal tract (CST) function after stroke, upper limb impairment resolves by ≈70% within 3 months. This is known as the proportional recovery rule. Patients without CST function do not fit this rule and have worse upper limb outcomes. This study investigated resolution of motor impairment in the lower limb (LL). Patients with stroke and LL weakness were assessed 3 days and 3 months after stroke with the LL Fugl–Meyer. CST integrity was determined in a subset of patients using transcranial magnetic stimulation to test for LL motor-evoked potentials and magnetic resonance imaging to measure CST lesion load. Linear regression analyses were conducted to predict resolution of motor impairment (ΔFugl–Meyer) including factors initial impairment, motor-evoked potential status, CST lesion load, and LL therapy dose. Thirty-two patients completed 3-month follow-up and recovered 74% (95% confidence interval, 60%–88%) of initial LL motor impairment. Initial impairment was the only significant predictor of resolution of motor impairment. There was no identifiable cluster of patients who did not fit the proportional recovery rule. Measures of CST integrity did not predict proportional LL recovery. LL impairment resolves by ≈70% within 3 months after stroke. The absence of a nonfitter group may be because of differences in the neuroanatomical organization of descending motor tracts to the upper limb and LL. Proportional recovery of the LL is not influenced by therapy dose providing further evidence that it reflects a fundamental biological process.
Publisher: Cold Spring Harbor Laboratory
Date: 02-11-2018
DOI: 10.1101/459776
Abstract: Inter-subject variability complicates trials of novel stroke rehabilitation therapies, particularly in the sub-acute phase after stroke. We tested whether selecting patients using motor evoked potential (MEP) status, a physiological biomarker of motor system function, could improve trial efficiency. A retrospective analysis of data from 207 patients (103 women, mean (SD) 70.6 (15.1) years) was used to estimate s le sizes and recruitment rates required to detect a 7-point difference between hypothetical control and treatment groups in upper-limb Fugl-Meyer and Action Research Arm Test scores at 90 days post-stroke. Analyses were carried out for the full s le and for subsets defined by motor evoked potential (MEP) status. Selecting patients according to MEP status reduced the required s le size by 75% compared to an unselected s le. The estimated time needed to recruit the required s le was also reduced by 72% for patients with MEPs, and was increased by 2-3-fold for patients without MEPs. Using biomarkers to select patients can improve stroke rehabilitation trial efficiency by reducing the s le size and recruitment time needed to detect a clinically meaningful effect of the tested intervention.
Publisher: American Physiological Society
Date: 05-2020
Abstract: Magnetic resonance spectroscopy indicated higher excitation-inhibition ratios within motor cortex during subacute recovery than age-similar healthy controls. Measures obtained from adaptive threshold hunting paired-pulse transcranial magnetic stimulation indicated greater tonic inhibition in patients compared with controls. Therapeutic approaches that aim to normalize motor cortex inhibition during the subacute stage of recovery should be explored.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2017
DOI: 10.1161/STROKEAHA.116.015790
Abstract: Several clinical measures and biomarkers are associated with motor recovery after stroke, but none are used to guide rehabilitation for in idual patients. The objective of this study was to evaluate the implementation of upper limb predictions in stroke rehabilitation, by combining clinical measures and biomarkers using the Predict Recovery Potential (PREP) algorithm. Predictions were provided for patients in the implementation group (n=110) and withheld from the comparison group (n=82). Predictions guided rehabilitation therapy focus for patients in the implementation group. The effects of predictive information on clinical practice (length of stay, therapist confidence, therapy content, and dose) were evaluated. Clinical outcomes (upper limb function, impairment and use, independence, and quality of life) were measured 3 and 6 months poststroke. The primary clinical practice outcome was inpatient length of stay. The primary clinical outcome was Action Research Arm Test score 3 months poststroke. Length of stay was 1 week shorter for the implementation group (11 days 95% confidence interval, 9–13 days) than the comparison group (17 days 95% confidence interval, 14–21 days P =0.001), controlling for upper limb impairment, age, sex, and comorbidities. Therapists were more confident ( P =0.004) and modified therapy content according to predictions for the implementation group ( P .05). The algorithm correctly predicted the primary clinical outcome for 80% of patients in both groups. There were no adverse effects of algorithm implementation on patient outcomes at 3 or 6 months poststroke. PREP algorithm predictions modify therapy content and increase rehabilitation efficiency after stroke without compromising clinical outcome. URL: anzctr.org.au . Unique identifier: ACTRN12611000755932.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2017
DOI: 10.1161/STROKEAHA.116.016020
Abstract: Recovery of upper-limb motor impairment after first-ever ischemic stroke is proportional to the degree of initial impairment in patients with a functional corticospinal tract (CST). This study aimed to investigate whether proportional recovery occurs in a more clinically relevant s le including patients with intracerebral hemorrhage and previous stroke. Patients with upper-limb weakness were assessed 3 days and 3 months poststroke with the Fugl–Meyer scale. Transcranial magnetic stimulation was used to test CST function, and patients were dichotomized according to the presence of motor evoked potentials in the paretic wrist extensors. Linear regression modeling of Δ Fugl–Meyer score between 3 days and 3 months was performed, with predictors including initial impairment (66 − baseline Fugl–Meyer score), age, sex, stroke type, previous stroke, comorbidities, and upper-limb therapy dose. One hundred ninety-two patients were recruited, and 157 completed 3-month follow-up. Patients with a functional CST made a proportional recovery of 63% (95% confidence interval, 55%–70%) of initial motor impairment. The recovery of patients without a functional CST was not proportional to initial impairment and was reduced by greater CST damage. Recovery of motor impairment in patients with intact CST is proportional to initial impairment and unaffected by previous stroke, type of stroke, or upper-limb therapy dose. Novel interventions that interact with the neurobiological mechanisms of recovery are needed. The generalizability of proportional recovery is such that patients with intracerebral hemorrhage and previous stroke may usefully be included in interventional rehabilitation trials. URL: www.anzctr.org.au . Unique identifier: ANZCTR12611000755932.
Publisher: Wiley
Date: 24-10-2017
DOI: 10.1002/ACN3.488
No related grants have been discovered for Marie-Claire Smith.