May clinical neurophysiology help to predict the recovery of neurological early rehabilitation patients?

Machine-Learning-Based Rehabilitation Prognosis Prediction in Patients with Ischemic Stroke Using Brainstem Auditory Evoked Potential

To evaluate the feasibility of brainstem auditory evoked potential (BAEP) for rehabilitation prognosis prediction in patients with ischemic stroke, 181 patients were tested using the Korean version of the modified Barthel index (K-MBI) at admission (basal K-MBI) and discharge (follow-up K-MBI). The BAEP measurements were performed within two weeks of admission on average. The criterion between favorable and unfavorable outcomes was defined as a K-MBI score of 75 at discharge, which was the boundary between moderate and mild dependence in daily living activities. The changes in the K-MBI scores (discharge-admission) were analyzed by nonlinear regression models, including the artificial neural network (ANN) and support vector machine (SVM), with the basal K-MBI score, age, and interpeak latencies (IPLs) of the BAEP (waves I, I-III, and III-V). When including the BAEP features, the correlations of the ANN and SVM regression models increased to 0.70 and 0.64, respectively. In the outcome prediction, the ANN model with the basal K-MBI score, age, and BAEP IPLs exhibited a sensitivity of 92% and specificity of 90%. Our results suggest that the BAEP IPLs used with the basal K-MBI score and age can play an adjunctive role in the prediction of patient rehabilitation prognoses.

Clinical neurophysiology of neurologic rehabilitation

Clinical neurophysiologic testing provides valuable support in predicting outcome in the setting of disorders of consciousness (DOC), including coma and traumatic brain injury (TBI). Electroencephalography (EEG) and evoked potentials (EP) are simple to apply, inexpensive, safe, and available in most rehabilitation facilities. This chapter reviews the use of EEG and EP in postanoxic coma and TBI. Bilateral absence of cortical somatosensory evoked potentials (SSEP) may be regarded as a predictor of poor outcome in hypoxic brain damage. Flash VEP may be useful to differentiate between good and poor outcome. In addition, low EEG frequencies, burst suppression, and isoelectric EEG patterns prognosticate poor outcomes in hypoxic brain damage. While a loss of cortical SSEP is generally regarded as a negative prognostic sign in the acute phase of hypoxic brain damage, absence of cortical SSEP responses is not necessarily associated with poor outcome in TBI. Event-related potentials (ERPs) can provide support in outcome prediction. In particular, the N100, mismatch negativity, P300, and N400 may improve accuracy of outcome prediction DOC of different etiologies. Some evidence suggests that ERPs may be superior to SSEP in predicting functional and DOC outcomes (Lew et al., 2003). ERPs are measured brain responses resulting from specific cognitive tasks, sensory stimulation, or planned motor activity.

Effects of somatosensory electrical stimulation on motor function and cortical oscillations

Background

Few patients recover full hand dexterity after an acquired brain injury such as stroke. Repetitive somatosensory electrical stimulation (SES) is a promising method to promote recovery of hand function. However, studies using SES have largely focused on gross motor function; it remains unclear if it can modulate distal hand functions such as finger individuation.

Objective

The specific goal of this study was to monitor the effects of SES on individuation as well as on cortical oscillations measured using EEG, with the additional goal of identifying neurophysiological biomarkers.

Methods

Eight participants with a history of acquired brain injury and distal upper limb motor impairments received a single two-hour session of SES using transcutaneous electrical nerve stimulation. Pre- and post-intervention assessments consisted of the Action Research Arm Test (ARAT), finger fractionation, pinch force, and the modified Ashworth scale (MAS), along with resting-state EEG monitoring.

Results

SES was associated with significant improvements in ARAT, MAS and finger fractionation. Moreover, SES was associated with a decrease in low frequency (0.9-4 Hz delta) ipsilesional parietomotor EEG power. Interestingly, changes in ipsilesional motor theta (4.8–7.9 Hz) and alpha (8.8–11.7 Hz) power were significantly correlated with finger fractionation improvements when using a multivariate model.

Conclusions

We show the positive effects of SES on finger individuation and identify cortical oscillations that may be important electrophysiological biomarkers of individual responsiveness to SES. These biomarkers can be potential targets when customizing SES parameters to individuals with hand dexterity deficits. Trial registration: NCT03176550; retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12984-017-0323-1) contains supplementary material, which is available to authorized users.

Critical illness polyneuropathy (CIP) in neurological early rehabilitation: clinical and neurophysiological features

BACKGROUND

Critical illness polyneuropathy (CIP) is a complex disease affecting 30-70% of critically ill patients.

METHODS

Clinical (Barthel index, length of stay (LOS), morbidity, duration of mechanical ventilation, routine lab results) and neurophysiological (neurography) data of 191 patients admitted to neurological early rehabilitation and diagnosed with CIP have been analyzed retrospectively.

RESULTS

CIP diagnosis was correct in 159 cases (83%). In this study, systemic inflammation, sepsis, systemic inflammatory response syndrome (SIRS), multiple organic failure (MOF), chronic renal failure, liver dysfunction, mechanical ventilation, diabetes, dyslipidemia and impaired ion homeostasis (hypocalcaemia, hypokalemia) were associated with CIP. Neurography, in particular of the peroneal, sural, tibial and median nerves, helped to identify CIP patients. Compound muscle action potential amplitude (r = -0.324, p < 0.05), as well as sensory (r = -0.389, p < 0.05) and motor conduction velocity (r = -0.347, p < 0.05) of the median nerve correlated with LOS in neurological early rehabilitation but not with outcome measures.

CONCLUSIONS

In most cases, diagnosis of CIP among neurological early rehabilitation patients seems to be correct. Neurography may help to verify the diagnosis and to learn more about CIP pathophysiology, but it does not allow outcome prediction. Further studies on CIP are strongly encouraged.