Neural correlates in the development of and recovery from dysphagia after supratentorial stroke: A prospective tractography study.

BACKGROUND: Swallowing impairment after stroke may be related to the state of the corticobulbar tract (CBT), which is the motor projection fiber responsible for deglutition, but evidence is still lacking regarding which parameter could relate to poststroke swallowing recovery as measured by videofluroscope findings. This prospective study evaluated diffusion tensor imaging (DTI) parameters among dysphagic stroke patients compared with those of nondysphagia stroke patients and age-matched healthy subjects and followed swallowing recovery in dysphagic patients as assessed with the Modified Barium Swallow Impairment Profile (MBSImP©). METHODS: Diffusion tractography was performed in 69 subjects, consisting of 27 S patients with dysphagia, 18 healthy subjects and 24 S patients with no evidence of dysphagia. DTI was performed within 14 days of stroke onset. Follow-up DTI was performed in the dysphagic group at three months. The tract volume (TV) of the CBT and frontal operculum as determined by fractional anisotropy (FA) was compared among the 3 groups. Correlations of these parameters with initial dysphagia severity and swallowing parameters at baseline and 3 months postonset were assessed. RESULTS: All stroke patients showed lower CBT TV on the affected and unaffected sides than those in the control group, even in those who showed no evidence of clinical dysphagia. The dysphagia group showed a greater reduction in CBT TV on the affected side (P < 0.001). Receiver operating characteristic analysis showed that cutoff values of 4.1 cm3 for TV and 0.24 for FA from the affected side could classify dysphagia with good accuracy (AUC = 0.77, 0.75, respectively) and specificity levels. FA values in the unaffected frontal operculum showed a significant correlation (rho = -0.40, P = 0.02) with swallowing outcome as observed by the total scores of MBSImP©. In addition, these values proved to be significant variables to predict swallowing outcome in multiple regression analysis (R2 = 0.6317, adjR2 = 0.5815, F = 12.58, p < 0.001, AIC = 203.65). CONCLUSIONS: Even when clinical dysphagia is not apparent, individuals with a supratentorial stroke may show reduced CBT parameters compared to healthy controls. Supratentorial stroke may manifest with dysphagia if a certain extent of CBT volume and white matter tract integrity is involved, with a greater degree of CBT injury in the affected sides determining poststroke dysphagia severity. In contrast, recovery was independent of the affected parameters, and an initial lower FA value in the unaffected frontal operculum was indicative of a poorer 3-month dysphagia outcome. DTI parameters obtained within two weeks of stroke onset may help classify those with dysphagia, predict recovery and help plain therapeutic strategies to maintain the adaptive role of the white matter tract, which is crucial in swallowing recovery.

Role of Catechol-O-methyltransferase Val158Met Polymorphism on Transcranial Direct Current Stimulation in Swallowing.

Transcranial direct current stimulation (tDCS) is one of the latest post-stroke dysphagia treatment modalities, and the effect of tDCS is known to be affected by various factors including genetic polymorphisms. However, the role of catechol-O-methyltransferase (COMT) polymorphisms on tDCS in swallowing is unclear. In this prospective pilot study, we aim to explore the effect of tDCS on the swallowing cortex and subsequent swallowing motor function according to COMT polymorphism. Twenty-four healthy participants received either anodal tDCS or sham mode tDCS on the mylohyoid motor cortex at random order, after inhibitory repetitive transcranial magnetic stimulation (rTMS) for preconditioning. The primary outcome was the changes of mylohyoid-motor-evoked potentials (MH-MEP) amplitude in each COMT polymorphism group, from the post-inhibitory rTMS baseline state to immediate, 30, and 60 min after tDCS. The secondary outcomes were the changes in swallowing function. The results showed that COMT Val/Val polymorphism showed improvement across time in the MH-MEP amplitudes and triggering time of swallowing after tDCS, whereas COMT Met carrier group did not show significant changes of MH-MEP or swallowing function across time. This therapeutic response variability of tDCS in the mylohyoid motor system according to COMT polymorphism support the importance of genetic analysis in individualized dysphagia treatment.

Can initial sarcopenia affect poststroke rehabilitation outcome?

This study investigated the association between the presence of sarcopenia, measured by nonhemiplegic grip strength, and the level of functional recovery, measured by the modified Rankin Scale (mRS) at six months after stroke. We performed a retrospective cohort analysis of a prospectively maintained database of 194 hemiplegic poststroke patients, who had been admitted to the Department of Rehabilitation Medicine of a university-affiliated hospital. At 6 months after stroke, 72.2% of patients had mRS score >3, with more women (81.0% vs. 66.0%, p = 0.024) showing poor recovery. Both men (51.3% vs. 35.9%, p = 0.041) and women (42.2% vs. 6.7%, p = 0.022) with mRS score >3 had a higher rate of sarcopenia. Univariate analysis revealed that the presence of sarcopenia was associated with a 2.71-fold higher risk of poor recovery at six months. In addition, women had a 2.18-fold higher risk of poor outcome. Multivariable logistic regression analysis revealed that the presence of sarcopenia was associated with poor functional outcome (odds ratio [OR] = 2.61, 95% confidence interval [CI]: 1.14-5.98, p = 0.024) in men, but this association was notably stronger in women (OR = 9.93, 95% CI: 1.22-81.19, p = 0.032). This study suggests that the presence of sarcopenia two weeks after stroke may increase the risk of poor functional outcome six months after stroke. Most notably, women with sarcopenia within 2 weeks from stroke onset were more significantly likely to have a poor modified Rankin Scale after 6 months.

Safe Needle Insertion Locations for Motor Point Injection of the Triceps Brachii Muscle: A Pilot Cadaveric and Ultrasonography Study.

OBJECTIVE: To determine the location of the motor endplate zones (MoEPs) for the three heads of the triceps brachii muscles during cadaveric dissection and estimate the safe injection zone using ultrasonography. METHODS: We studied 12 upper limbs of 6 fresh cadavers obtained from body donations to the medical school anatomy institution in Seoul, Korea. The locations of MoEPs were expressed as the percentage ratio of the vertical distance from the posterior acromion angle to the midpoint of the olecranon process. By using the same reference line as that used for cadaveric dissection, the safe injection zone away from the neurovascular bundle was identified in 6 healthy volunteers via ultrasonography. We identified the neurovascular bundle and its location with respect to the distal end of the humerus and measured its depth from the skin surface. RESULTS: The MoEPs for the long, lateral, and medial heads were located at a median of 43.8%, 54.8%, and 60.4% of the length of the reference line in cadaver dissection. The safe injection zone of the medial head MoEPs corresponded to a depth of approximately 3.5 cm from the skin surface and 1.4 cm away from the humerus, as determined by sonography. CONCLUSION: Correct identification of the motor points for each head of the triceps brachii would increase the precision and efficacy of motor point injections to manage elbow extensor spasticity.

Determining Peak Cough Flow Cutoff Values to Predict Aspiration Pneumonia Among Patients With Dysphagia Using the Citric Acid Reflexive Cough Test.

OBJECTIVE: To investigate the clinical usefulness of the peak cough flow generated during the citric acid reflexive cough test (0.28 mol/L) by determining the appropriate cutoff values that could accurately predict aspiration pneumonia within the first 6 months after onset. DESIGN: Retrospective analysis of a prospectively maintained database. SETTING: University-affiliated hospital. PARTICIPANTS: Patients (N=163) with first-ever diagnosed dysphagia attributable to cerebrovascular disease, who had undergone the citric acid reflexive cough test on the same day they underwent the instrumental assessment of swallowing, such as videofluoroscopy or the functional endoscopic swallowing test. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Peak cough flow (L/min) from the citric acid reflexive cough test. RESULTS: A final 163 patients had full medical records with 6-month follow-up. Receiver operating curve analysis showed that peak cough flow cutoff values set at 59 L/min were significantly associated with aspiration pneumonia (area under the curve [AUC] 95% confidence interval =0.88 [0.83-0.93]). This cutoff value significantly (P<.001) predicted the risk of aspiration pneumonia with an odds ratio of 21.56 (9.62-48.28). A multivariate regression logistic regression analysis model including initial dysphagia severity, low body mass index, and decreased level of cognition showed that inclusion of the peak cough flow from the citric acid reflexive cough test significantly improved the predictive model of aspiration pneumonia within the first 6 months after onset (AUC=0.91 vs 0.79). CONCLUSIONS: Those with reflexive cough strength less than 59 L/min may be at high risk of respiratory infections within the first 6 months after dysphagia onset. Objective measurement of reflexive cough strength may help to predict those at risk of aspiration pneumonia.