Evidence of lateralised white matter plasticity: A longitudinal study of balance performance in nonexpert healthy adults.

Training-induced plasticity by practicing expert skills has been of particular interest; however, little is known about white matter plasticity for improving a fundamental element of body function, such as balance or postural control. This study explored white matter plasticity in nonexpert healthy adults, based on stepwise balance training. Seventeen participants were included and performed a home-based balance training program for 4 weeks (30 min/day, 3 days/week). Before commencing training, they underwent a baseline diffusion tensor imaging scan. A second scan was acquired at the end of the 4-week training. Lateralised balance load was applied on the right leg to contrast any lateralised effect on the white matter tracts. The balance function was assessed using the Community Balance & Mobility Scale. We examined changes in the fractional anisotropy values of the tracts of interest between pre- and post-training. After the 4-week training, the fractional anisotropy values were enhanced in the right superior cerebellar peduncle, transverse pontine fibre, body of the corpus callosum, left fornix and left uncinate fasciculus. The Community Balance & Mobility Scale score improved after 4-week training, but an association with changes in fractional anisotropy values cannot be evaluated due to the ceiling effect of the balance assessment tools. Balance training can strengthen the cerebro-cerebellar and interhemispheric structural connections and induce microstructural changes in the limbic structures, including the fornix and uncinate fasciculus. The effect of a lateralised balance load could be projected to the specific white matter tracts in a lateralised manner.

Detection of post-stroke visual field loss by quantification of the retrogeniculate visual pathway.

Visual field loss is associated with poor post-stroke functional outcomes. However, early detection of visual field loss is often challenging in patients with disabling stroke. This study explored the association between the microstructural integrity of the retrogeniculate pathway and visual field loss in disabling stroke patients undergoing inpatient rehabilitation. Thirty patients with stroke lesions involving the retrogeniculate visual pathway were included. The degree of visual field loss was determined by the visual field index and mean deviation using automated perimetry. The fractional anisotropy (FA) values were obtained for the lateral geniculate nucleus and optic radiation; the FA laterality indices, representing the degree of degeneration, were calculated. The FA values were compared between the affected and unaffected hemispheres. The patients were categorized into complete and incomplete hemianopia groups, and their FA values were compared. The relationship between the FA laterality index and the degree of visual field loss was assessed. FA values of the lateral geniculate nucleus and optic radiation were lower on the affected side than on the unaffected side (P < 0.001 and P < 0.001, respectively). The affected optic radiation in the complete hemianopia group showed a lower FA value than in the incomplete group (P = 0.006). The FA laterality index of the optic radiation was positively correlated with the degree of visual field loss (visual field index, ρ = 0.629; mean deviation, ρ = 0.568). The quantification of the retrogeniculate visual pathway may aid in detecting post-stroke visual field loss. The microstructural integrity of the optic radiation is associated with the severity of visual field loss.

Integrity of the Inferior Cerebellar Peduncle Correlates with Ambulatory Function after Hemorrhagic Stroke.

OBJECTIVES: Cerebro-cerebellar connectivity plays a critical role in motor recovery after stroke; however, the underlying mechanism of walking recovery is unclear. The dorsal spinocerebellar pathway has been suggested as a biomarker of poststroke ambulatory function. We aimed to explore the association between ambulatory function and the dorsal spinocerebellar pathway's integrity after intracerebral hemorrhage (ICH). MATERIALS AND METHODS: Twenty-seven patients with ICH who were admitted for inpatient rehabilitation during the subacute phase of stroke and 27 age-matched healthy controls were included retrospectively. Ambulatory function was assessed using the Berg Balance Scale and Mobility score. We measured the fractional anisotropy (FA) values of the corticospinal tract (CST) and inferior cerebellar peduncle (ICP) as the final route of the dorsal spinocerebellar pathway. The FA laterality indices, representing the degree of degeneration, were calculated. A Spearman correlation analysis and multivariate linear regression models were used to determine the associations between the FA laterality indices and ambulatory function. RESULTS: An FA reduction was found in both the ipsilesional CST and contralesional ICP of the patients. The ICP FA laterality index exhibited a moderate correlation with ambulatory function (Berg Balance Scale, ρBBS=0.589; Mobility score, ρMS=0.619). On dividing the patient group into the moderate (mRS 3, 4) and severe disability (mRS 5) groups, a stronger correlation was found (ρBBS=0.777, ρMS=0.856, moderate disability; ρBBS=0.732, ρMS=0.797, severe disability). The ICP FA laterality index and age were independently associated with the Mobility score (R2=0.525). CONCLUSIONS: ICP degeneration occurs after ICH, and its degree is associated with ambulatory function after ICH.

Degeneration of the Inferior Cerebellar Peduncle After Middle Cerebral Artery Stroke: Another Perspective on Crossed Cerebellar Diaschisis.

Background and Purpose- Deafferentation of the cortico-ponto-cerebellar pathway has been proposed as a key mechanism of crossed cerebellar diaschisis. Although the cerebellum receives afferent stimuli from both cortico-ponto-cerebellar and spinocerebellar pathways, evidence on whether spinocerebellar deafferentation contributes to a hypofunctional cerebellum is lacking. Therefore, we aimed to determine whether changes in the spinocerebellar pathway occur after middle cerebral artery stroke. Methods- Twenty-three patients admitted to our inpatient rehabilitation facility and 23 age-matched healthy controls were retrospectively enrolled. Patients' functional ambulation category was determined and the Medical Research Council muscle scale test of the lower limb muscles was performed at admission and discharge. The fractional anisotropy (FA) values of the corticospinal tract and the inferior cerebellar peduncle (ICP), as the final route of the dorsal spinocerebellar pathway, were compared between the groups. The FA laterality indices of the ICP and corticospinal tract were calculated as follows: (FAaffected-FAunaffected)/(FAaffected+FAunaffected). Pearson correlation analysis and multivariate linear regression models were used to determine the associations between the FA laterality indices and ambulatory function. Results- The FAs of the corticospinal tract and ICP were lower in the patient group than in the control group. The FA laterality index of the corticospinal tract was not correlated with the functional ambulation category or Medical Research Council muscle scale score at admission or discharge. The FA laterality index of the ICP at the pontomedullary junction was positively correlated with the functional ambulation category and Medical Research Council muscle scale scores of all hemiplegic lower limb muscles at admission and discharge. The FA laterality index of the ICP at the pontomedullary junction was independently associated with the functional ambulation category according to the multivariate regression models. Conclusions- ICP degeneration occurs in the subacute and early chronic phase of middle cerebral artery stroke. The lower FA laterality index of the ICP was indicative of poorer ambulatory and lower limb function.

Can diffusion tensor imaging and tractography represent cross-sectional area of lumbar multifidus in patients with LUMBAR spine disease?

INTRODUCTION: Cross-sectional area (CSA) is a useful measurement to evaluate the lumbar multifidus, but it cannot reflect the morphological characteristics of the entire muscle. Recently, diffusion tensor imaging (DTI) and tractography (DTT) have been used to assess 3-dimensional muscle structures both qualitatively and quantitatively. In this study we investigate the correlation between CSA and multifidus volume and the clinical utility of DTI and DTT. METHODS: Twenty-eight lumbar multifidi from 14 subjects with lumbar spine disease were analyzed. We conducted correlation analysis between CSA from conventional magnetic resonance images and DTI-derived parameters, including muscle volume, fractional anisotropy (FA), and mean diffusivity (MD); we performed morphological assessment using DTT. RESULTS: Multifidus volume had a strong positive correlation with CSA (r = 0.760, P < 0.001). Neither FA nor MD correlated with CSA. Multifidi spanning fewer vertebral segments were smaller in volume. DISCUSSION: DTT can be a valuable tool to visualize and quantify the lumbar multifidus in lumbar spine disease. Muscle Nerve 57: 200-205, 2018.

Anatomical Localization of Motor Points of the Abductor Hallucis Muscle: A Cadaveric Study.

OBJECTIVE: To identify the anatomical motor points of the abductor hallucis muscle in cadavers. METHODS: Motor nerve branches to the abductor hallucis muscles were examined in eight Korean cadaver feet. The motor point was defined as the site where the intramuscular nerve penetrates the muscle belly. The reference line connects the metatarsal base of the hallux (H) to the medial tubercle of the calcaneus (C). The x coordinate was the horizontal distance from the motor point to the point where the perpendicular line from the navicular tuberosity crossed the reference line. The y coordinate was the perpendicular distance from the motor point to the navicular tuberosity. RESULTS: Most of the medial plantar nerves to the abductor hallucis muscles divide into multiple branches before entering the muscles. One, two, and three motor branches were observed in 37.5%, 37.5%, and 25% of the feet, respectively. The ratios of the main motor point from the H with respect to the H-C line were: main motor point, 68.79%±5.69%; second motor point, 73.45%±3.25%. The mean x coordinate value from the main motor point was 0.65±0.49 cm. The mean value of the y coordinate was 1.43±0.35 cm. All of the motor points of the abductor hallucis were consistently found inferior and posterior to the navicular tuberosity. CONCLUSION: This study identified accurate locations of anatomical motor points of the abductor hallucis muscle by means of cadaveric dissection, which can be helpful for electrophysiological studies in order to correctly diagnose the various neuropathies associated with tibial nerve components.

Identification of early neurodegenerative change in presymptomatic spinocerebellar ataxia type 1: A diffusion tensor imaging study.

We report a 41-year-old man of presymptomatic spinocerebellar ataxia type 1. Diffusion tensor imaging (DTI) verified decreased fractional anisotropy of cerebellar afferent and efferent pathways compared to 5 age-matched healthy controls while conventional MRI revealed normal brain. DTI was valuable in detection of early microstructural damage of cerebellar pathways.

Prolonged Motor Weakness With Syringomyelia in Japanese Encephalitis: A Case Study.

Japanese encephalitis (JE) shows characteristic brain lesions, including bilateral thalamus, midbrain, internal capsule, basal ganglia, and occasionally involves an anterior horn cell. We encountered a case of a 44-year-old man who initially presented with encephalitis, which was finally diagnosed as Japanese encephalomyelitis with syringomyelia. The patient showed severe motor weakness followed by delayed recovery of functional motor activities. Cervical magnetic resonance imaging showed syrinx formation at the C5 level suggesting myelitis, and abnormal electromyographic findings were noted. Clinicians should consider the possibility that the spinal cord may be involved; an example would be syringomyelia due to myelitis in a case of JE presenting with severe and prolonged motor weakness.

Do not rush to return to sports after trigger finger injection.

Trigger finger, or digital stenosing tenosynovitis, is a common hand problem. A widely accepted treatment is steroid injection into the flexor tendon sheath. This can cause rupture of the flexor tendon. However, to the best of our knowledge, there is no report on tendon rupture after a single corticosteroid injection. Moreover, there are no guidelines for patients with tendinopathy who want to return to sports after corticosteroid injection. Clinicians who perform local steroid injections for tendinopathy treatment should be aware of the possible dangers of tendon rupture and should confirm that steroids are not administrated into the tendon. Patients should also be warned about returning to sports prematurely and should be encouraged to gradually resume sports after the injection to prevent further damage. Herein, we report an unusual case of flexor digitorum profundus rupture after a single corticosteroid injection in a 57-yr-old male golfer and we also present a review of the literature.