Maximal Resection of Gliomas Adjacent to the Corticospinal Tract Using 3-T Intraoperative Magnetic Resonance Imaging

BACKGROUND

Gliomas adjacent to the corticospinal tract (CST) should be carefully resected to preserve motor function while achieving maximal surgical resection. Modern high-field intraoperative magnetic resonance imaging (iMRI) enables precise visualization of the residual tumor and intraoperative tractography. We prospectively evaluated the extent of resection and distance between the tumor resection cavity and CST using 3-T iMRI combined with motor evoked potentials (MEP) in glioma surgery.

METHODS

Participants comprised patients who underwent surgery for solitary supratentorial glioma located within 10 mm of the CST. All cases underwent surgery using neuronavigation with overlaid CST under MEP monitoring. The correlation between distance from CST and transcortical MEP amplitude was calculated using Spearman rank correlation.

RESULTS

Among the 63 patients who underwent surgery, 27 patients were enrolled in the study. Gross total resections were achieved in 26 of the 27 cases. Volumetric analysis showed the extent of resection was 98.6%. Motor function was stable or improved in 24 patients (Stable/Improved group) and deteriorated in 3 patients (Deteriorated group). All patients in the Deteriorated group showed motor deficit before surgery. Mean intraoperative minimal distance was significantly longer in the Stable/Improved group (7.3 mm) than in the Deteriorated group (1.1 mm; P < 0.05). MEP amplitude correlated with minimal distance between the resection cavity and CST (R = 0.64).

CONCLUSIONS

Resection of gliomas adjacent to CST with a navigation system using 3-T iMRI could result in an ultimate EOR >98%. The combination of intraoperative tractography and MEP contributes to maximal removal of motor-eloquent gliomas.

The efficacy of preoperative diffusion tensor tractography on surgical planning and outcomes in patients with intramedullary spinal tumor

PURPOSE

The aim of this study was to investigate the efficacy of diffusion tensor tractography (DTT) of spinal cord on surgical planning and postoperative neurological outcomes in patients with spinal intramedullary tumors.

METHODS

The study was conducted retrospectively from the radiological and clinical data of our hospital database. Patients with intramedullary spinal cord tumors who underwent diffusion tensor imaging for spinal cord lesions were selected between 2019 and 2022. Demographic characteristics and intraoperative neurophysiological monitoring data were evaluated. The McCormick scale was used to grade the pre- and postoperative neurological status of the patients. The tumoral lesions were categorized into 3 types according to the fiber course on DTT.

RESULTS

Eleven patients were found to have radiological findings that were compatible with intramedullary tumor; eight (72.7%) of them ultimately underwent surgery following being approved as surgical candidates in the spinal diffusion tensor imaging studies. Six cases had Type 1, one case had Type 2, and 4 cases had Type 3 tumors according to the fiber course. All Type 1 tumors were classified as resectable and all of them were gross totally resected. Type 2 lesion that was rated as resectable by DTI was subtotally resected. Type 3 lesions were followed without surgery except the one with tumoral progression and neurological deficit. The postoperative neurological outcomes were compatible with intraoperative neurophysiological monitoring results.

CONCLUSION

Diffusion tensor imaging and tractography may be beneficial regarding the selection of patients suitable for surgery and in the subsequent surgical planning.

Elevated intraspinal pressure drives edema progression after acute compression spinal cord injury in rabbits

Elevated intraspinal pressure (ISP) following traumatic spinal cord injury (tSCI) can be an important factor for secondary SCI that may result in greater tissue damage and functional deficits. Our present study aimed to investigate the dynamic changes in ISP after different degrees of acute compression SCI in rabbits with closed canals and explore its influence on spinal cord pathophysiology. Closed balloon compression injuries were induced with different inflated volumes (40 μl, 50 μl or no inflation) at the T7/8 level in rabbits. ISP was monitored by a SOPHYSA probe at the epicenter within 7 days post-SCI. Edema progression, spinal cord perfusion and damage severity were evaluated by serial multisequence MRI scans, somatosensory evoked potentials (SEPs) and behavioral scores. Histological and blood spinal cord barrier (BSCB) permeability results were subsequently analyzed. The results showed that the ISP waveforms comprised three peaks, significantly increased after tSCI, peaked at 72 h (21.86 ± 3.13 mmHg) in the moderate group or 48 h (31.71 ± 6.02 mmHg) in the severe group and exhibited "slow elevated and fast decreased" or "fast elevated and slow decreased" dynamic changes in both injured groups. Elevated ISP after injury was correlated with spinal cord perfusion and edema progression, leading to secondary lesion enlargement. The secondary damage aggravation can be visualized by diffusion tensor tractography (DTT). Moreover, the BSCB permeability was significantly increased at the epicenter and rostrocaudal segments at 72 h after SCI; by 14 days, notable permeability was still observed at the caudal segment in the severely injured rabbits. Our results suggest that the ISP of rabbits with closed canals increased after acute compression SCI and exhibited different dynamic change patterns in moderately and severely injured rabbits. Elevated ISP exacerbated spinal cord perfusion, drove edema progression and led to secondary lesion enlargement that was strongly associated with BSCB disruption. For severe tSCI, early intervention targeting elevated ISP may be an indispensable choice to rescue spinal cord function.

Assessment of acute traumatic cervical spinal cord injury using conventional magnetic resonance imaging in combination with diffusion tensor imaging-tractography: a retrospective comparative study

PURPOSE

The application of conventional magnetic resonance imaging (MRI) in combination with diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) to diagnose acute traumatic cervical SCI has not been studied. This study explores the role of MRI with DTI-DTT in the diagnosis of acute traumatic cervical spinal cord injury (SCI).

METHODS

Thirty patients with acute traumatic cervical SCI underwent conventional MRI and DTI-DTT. Conventional MRI was used to detect the intramedullary lesion length (IMLL) and intramedullary hemorrhage length (IMHL). DTI was used to detect the spinal cord's fractional anisotropy (FA) and apparent diffusion coefficient value, and DTT detected the imaginary white matter fiber volume and the connection rates of fiber tractography (CRFT). Patients' neurological outcome was determined using the American Spinal Injury Association (ASIA) Impairment Scale (AIS) grades.

RESULTS

Patients were divided into group A (without AIS grade conversion) and group B (with AIS grade conversion). The IMLL and IMHL of group A were significantly higher than those of group B. The FA and CRFT of group A were significantly lower than those of group B. The final AIS grade was negatively correlated with the IMLL and IMHL, and positively correlated with the FA and CRFT. According to imaging features based on conventional MRI and DTI-DTT, we propose a novel classification and diagnostic procedure.

CONCLUSIONS

The combination of conventional MRI with DTI-DTT is a valid diagnostic approach for SCI. Lower IMLL and IMHL, and higher FA value and CRFT are linked to better neurological outcomes.

Relationship between short-term memory impairment and the dorsolateral prefrontal cortex injury in patients with mild traumatic brain injury

BACKGROUND

The prefrontal cortex (PFC) has been reported to be related to memory function. Especially, the dorsolateral PFC (DLPFC) is a substantial neural structure in short-term memory. In this study, using diffusion tensor tractography (DTT), we investigated the relationship between short-term memory impairment and the DLPFC injury in patients with mild traumatic brain injury (TBI).

METHODS

We recruited 46 consecutive chronic patients with mild TBI and 42 normal control subjects. Fractional anisotropy (FA) and fiber number (FN) of the prefronto-thalamic tracts were determined for both hemispheres.

RESULTS

Significant differences were detected in the FA value of the DLPFC and FN value of the prefronto-thalamic tracts in the patient and control groups (p < 0.05). However, no significant differences were detected in the ventrolateral PFC (VLPFC) and orbitofrontal cortex (OFC) between the patient and control groups (p > 0.05). In addition, the FN value of the DLPFC showed moderate positive correlation with short-term memory (r = 0.510, p < 0.05). However, no significant correlations were detected between the short-term memory and the FA value of the DLPFC, and the FA and FN values of the VLPFC and OFC in the patient group (p > 0.05).

CONCLUSIONS

We found that the short-term memory impairment was closely associated with the DLPFC injury in patients with mild TBI. Our results suggest that the estimation of the DLPFC using DTT would be useful for patients with severity of short-term memory impairment following mild TBI.

Altered Structural and Functional Connectivity of Salience Network in Patients with Classic Trigeminal Neuralgia

Classic trigeminal neuralgia (CTN) is a neuropathic pain disorder displaying spontaneously stabbing or electric shock-like paroxysms in the face. Previous research suggests structural and functional abnormalities in brain regions related to sensory and cognitive-affective dimensions of pain contribute to the pathophysiology of CTN. However, few studies to date have investigated how changes in whole-brain functional networks and white matter connectivity are related to CTN. We performed an independent component analysis to examine abnormalities in resting state functional connectivity of large-scale networks in 48 patients with CTN compared to 46 matched healthy participants. Then, diffusion tensor tractography was performed to test whether these alterations of functional connectivity in intrinsic networks were associated with impairment of the white matter tracts connecting them. Distinct patterns of functional connectivity were detected within default mode network, somatosensory network, and salience network (SN) in the CTN group when compared with healthy controls. Furthermore, abnormality of SN was negatively correlated with pain severity. In support of aberrant functional connectivity within SN, structural disintegration was observed in the white matter tract from left anterior insula (aIns) to left anterior cingulate cortex (ACC) in CTN. These results suggest that altered structural and functional connectivity between aIns and ACC may underpin the aberrant SN in patients with CTN and provide an alternative target for clinical interventions. PERSPECTIVE: This article presents distinctive abnormalities of functional and structural connectivity from aIns to ACC in the patients with CTN, which is associated with pain ratings. This measure could potentially provide an alternative target for clinicians to alleviate this type of intermittent and refractory pain.

Musician developed left putaminal hemorrhage and lost absolute pitch ability-case report

Absolute pitch (AP) recognizes and labels the pitch chroma of a given tone without external reference. Its neural mechanism remains unclear. We report a 68-year-old AP musician who developed a left putaminal hemorrhage edematous lesion under the posterior insular cortex. Diffusion tensor tractography with the region of interest, including Heschl's gyrus, was performed. In the left hemisphere, the middle longitudinal fasciculus was absent, especially at the parietal lobe. Her AP ability was lost. As the hematoma was absorbed and the left MdLF was observed on the tractography, her AP ability recovered. Our case suggested that the left middle longitudinal fasciculus, a part of the ventral auditory pathway, plays a role in AP.

Non-motor connections of the pedunculopontine nucleus of the rat and human brain

INTRODUCTION

The connections of the pedunculopontine nucleus (PPN) with motor areas of the central nervous system (CNS) are well described in the literature, in contrast relations with non-motor areas are lacking. Thus, the aim of the present study is to define the non-motor connections of the PPN in rats using the fluoro-gold (FG) tracer and compare the presence of these connections in healthy human adults using diffusion tensor tractography (DTI).

MATERIALS AND METHODS

We injected FG into the PPN of 12 rats. The non-motor connections of the PPN with cortical, subcortical, and brainstem structures were documented. The non-motor connections of the rats were compared with the DTI obtained from 35 healthy adults.

RESULTS

The results of the tract-tracing study in the rat showed that the PPN was connected to non-motor cortical (cingulate, somatosensory, visual, auditory, medial frontal cortices), subcortical (amygdala, hypothalamus, thalamus, habenular, and bed nucleus of stria terminalis), and brainstem (medullary reticular, trigeminal spinal, external cuneate, pontine reticular, vestibular, superior and inferior colliculus, locus ceruleus, periaqueductal gray, parabrachial, dorsal raphe, pretectal, lateral lemniscus nuclei, and the contralateral PPN) structures. The DTI obtained from healthy adults showed similar PPN non-motor connections as in rats.

CONCLUSION

Understanding the connections of the PPN with non-motor cortical, subcortical, and brainstem areas of the CNS will enrich our knowledge of its contribution in various circuits and the areas that PPN activity can influence. Further, it will provide insight into the role of Parkinson's disease and related disorders and explain the non-motor complications which occur subsequent to deep brain stimulation (DBS) of the PPN.

Relationships among language ability, the arcuate fasciculus and lesion volume in patients with putaminal hemorrhage: a diffusion tensor imaging study

Relationships among language ability, arcuate fasciculus and lesion volume were investigated by use of diffusion tensor tractography in patients with putaminal hemorrhage. Thirty-three right-handed patients within six weeks of hemorrhage onset were recruited. Correlation of the aphasia quotient with subset (fluency, comprehension, repetition, naming) scores, diffusion tensor tractography parameters and lesion volume of patients, aphasia quotient (r = 0.446) with subset (naming: r = 0.489) score had moderate positive correlations with fractional anisotropy of the left arcuate fasciculus. The aphasia quotient subset (repetition) score had a strong positive correlation with fractional anisotropy of the left arcuate fasciculus (r = 0.520), whereas, aphasia quotient subset (fluency and comprehension) scores had no significant correlations with fractional anisotropy of the left arcuate fasciculus after Benjamini-Hochberg correction. Aphasia quotient (r = 0.668) with subset (fluency: r = 0.736, comprehension: r = 0.739, repetition: r = 0.649, naming: r = 0.766) scores had strong positive correlations with the tract volume of the left arcuate fasciculus and strong negative correlations with lesion volume (r = -0.521, fluency: r = -0.520, comprehension: r = -0.513, repetition: r = -0.518, naming: r = -0.562). Fractional anisotropy of the left arcuate fasciculus had a moderate negative correlation with lesion volume (r = -0.462), whereas the tract volume of the left arcuate fasciculus had a strong negative correlation with lesion volume (r = -0.700). According to the result of mediation analysis, tract volume of the left arcuate fasciculus fully mediated the effect of lesion volume on the aphasia quotient. Regarding the receiver operating characteristic curve, the lesion volume cut-off value was 29.17 cm³ and the area under the curve (0.74), sensitivity (0.77) and specificity (0.80) were higher than those of fractional anisotropy, tract volume and aphasia quotient cut-off values. It was found that level of language disability was related to lesion volume as well as to injury severity of arcuate fasciculus in the dominant hemisphere of patients with putaminal hemorrhage. In particular, the tract volume of the arcuate fasciculus in the dominant hemisphere fully mediated the effect of lesion volume on language ability. Additionally, a lesion volume of approximately 30 cm³ was helpful in discriminating arcuate fasciculus discontinuation in the dominant hemisphere.

Recovery of the ascending reticular activating system and consciousness following comprehensive management in a patient with traumatic brain injury

We report on changes in the ascending reticular activating system (ARAS) concurrent with the recovery of impaired consciousness following rehabilitation and cranioplasty in a patient with traumatic brain injury (TBI), which were demonstrated on diffusion tensor tractography (DTT). A 34-year-old male patient was diagnosed with a traumatic intracerebral hemorrhage after falling from a height of approximately 7 m and underwent a right frontoparietotemporal decompressive craniectomy and hematoma removal. At 5 months after onset, when starting rehabilitation, the patient showed impaired consciousness, with a Glasgow Coma Scale (GCS) score of 4. Comprehensive rehabilitative therapy was provided until 14 months after onset, and his GCS score improved to 8. Cranioplasty was performed using auto-bone at 14 months after onset. One month after cranioplasty, his GCS score improved to 12. On the 15-month DTT, the deviated lower dorsal ARAS was restored on both sides, and the right side had become thicker. The right lower ventral ARAS was reconstructed, and increased neural connectivity of the upper ARAS was detected in both the prefrontal cortices. Thus, changes in the ARAS were demonstrated in a patient with TBI during recovery of consciousness following rehabilitation and cranioplasty.

Does injury of the thalamocortical connection between the mediodorsal nucleus of the thalamus and the dorsolateral prefrontal cortex affect motor recovery after cerebral infarct?

We assessed the state of the thalamocortical connection between the mediodorsal nucleus (MD) and the dorsolateral prefrontal cortex (DLPFC) in patients with corona radiata infarct using diffusion tensor tractography (DTT). Altogether, 110 patients with corona radiata infarct were recruited, all of whom underwent DTT at an early stage following infarct onset. Based on the integrity of CST (CST+: CST was preserved around the infarct, CST-: CST was interrupted by the infarct) and the integrity of thalamocortical connection between the MD of thalamus and the DLPFC (DLPFC+: the connection was preserved, DLPFC-: the connection was interrupted), patients were divided into 4 groups: CST+/DLPFC+ (37 patients), CST+/DLPFC- (21 patients), CST-/DLPFC+ (25 patients), and CST-/DLPFC- (27 patients) groups. Motor function was evaluated using the upper Motricity Index (MI), lower MI, modified Brunnstrom classification, and the functional ambulation category at baseline and at 6 months post-onset. In patients with preserved CST integrity, the status of the thalamocortical connection had no impact on the assessed motor outcomes at 6 months post-stroke. However, in patients with disrupted CST integrity, those with preserved thalamocortical connection integrity had significantly higher motor function scores in all assessed outcomes 6 months post-stroke than those with disrupted thalamocortical connection integrity. The preservation or disruption of the thalamocortical connection between the MD of the thalamus and the DLPFC is an important factor for motor function recovery when CST integrity is also disrupted.

A case with bilateral thalamic infarction manifesting mutism - Cerebral blood flow and neural fibers evaluation

Background:

Acute bilateral thalamic infarction is rare, and occlusion of the artery of percheron (AOP) may be one of its reasons. AOP occlusion results in an acute disturbance of consciousness, but mutism due to AOP occlusion is rare. We described a mutism patient with bilateral thalamic infarction presumably due to AOP occlusion. We also performed cerebral blood flow (CBF) evaluation by N-isopropyl-p-[¹²³I]-iodoamphetamine single-photon emission computed tomography (¹²³I-IMP-SPECT) as well as neural fiber evaluation by diffusion tensor tractography, discussing the mechanism of mutism.

Case Description:

A 92-year-old woman presented a gradual deterioration of consciousness. Diffusion-weighted images revealed high-intensity areas at the bilateral thalami, and we diagnosed AOP occlusion. We administered a recombinant tissue plasminogen activator. On day 14, her Glasgow Coma Scale score was 11 (E4V1M6), and she did not present any apparent paresis. She was mute but cognitively alert, although she could communicate by nodding or facial expression. ¹²³I-IMP-SPECT showed CBF increase in the bilateral cerebellum and CBF decrease in the infarcted bilateral thalami and frontal lobes. Diffusion tensor tractography revealed the bilateral dentatothalamo-cortical tracts (DTCs). However, the tracts terminated at the parieto-occipital cortex, but not at the frontal cortex. She still had mutism on day 30.

Conclusion:

We reported the bilateral thalamic infarction patient presumably due to AOP occlusion, who presented mutism. The discontinuity of the bilateral DTCs resulted in her mutism, and our results supported the hypothesis that the cerebellum plays a significant role in uttering, associated with the bilateral DTCs.

The Role of Diffusion Tensor Imaging and Diffusion Tensor Tractography in the Assessment of Acute Traumatic Thoracolumbar Spinal Cord Injury

BACKGROUND

This study explored diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) to assess the prognosis of thoracolumbar spinal cord injury (SCI).

METHODS

Twenty patients with acute traumatic thoracolumbar complete SCI (T1-L1, American Spinal Injury Association Impairment Scale [AIS] grade A) underwent conventional magnetic resonance imaging and DTI examinations. DTI measured the fractional anisotropy (FA) and apparent diffusion coefficient adjacent to the lesion epicenter. DTT was used to detect the white matter fiber morphology and measure the imaginary white matter fiber volume and connection rates of fiber tractography (CRFT). The patients' neurological functions were evaluated by the AIS grades.

RESULTS

At the final-follow-up, among the 20 patients with AIS grade A, 15 maintained the AIS grade (group A), and 5 patients showed improvement of AIS grade (group B). Group A's mean FA value was significantly lower than that of group B, whereas the mean apparent diffusion coefficient value among the 2 groups showed no significant difference. The white matter fibers of most patients in group A were completely ruptured (11/15), but the white matter fibers of all patients in group B were retained in different number (5/5). The mean CRFT of group B was significantly higher than that of group A (P < 0.05). The improvement of AIS grade was slightly positively correlated with FA values and highly positively correlated with CRFT.

CONCLUSIONS

The prognosis of complete thoracolumbar SCI may be related to the FA value and the CRFT. The application of DTI and DTT may optimize the diagnosis of thoracolumbar SCI.

Musician developed right putaminal hemorrhage but conserved absolute pitch ability -Case report

Absolute pitch (AP) is known as the ability to recognize and label the pitch chroma of a given tone without external reference. The neural mechanism and its asymmetry of AP musicians remain unclear. We herein report a 41-year-old AP musician who developed a right putaminal hemorrhage. On a postoperative day 5, a fluid-attenuated inversion recovery image revealed the rest of the hematoma and edematous lesion at the right white matter between the Heschl's gyrus and other cortices. Diffusion tensor tractography with the region of interest at the Heschl's gyrus was performed. In the left hemisphere, the anterior part of the arcuate fiber and middle longitudinal fasciculus were observed. However, these connections were absent in the right hemisphere, but her AP ability was maintained. Our case suggested that the fibers from the right Heschl's gyrus to the right frontal lobe via the right ventral stream is not associated with AP.

The Complex Structure of the Anterior White Commissure of the Human Brain: Fiber Dissection and Tractography Study

OBJECTIVE

Commissural fibers are necessary for bilateral integration, body coordination, and complex cognitive information flow between the hemispheres. The anterior commissure (AC) has a complex architecture interconnecting areas of the frontal, temporal and occipital lobes. The present study aims to demonstrate the connections and the course of the anterior (ACa) and posterior (ACp) limb of the AC using fiber dissection and diffusion tensor imaging (DTI) of the human brain.

METHODS

Fiber dissection was performed in a stepwise manner from lateral to medial on 6 left hemispheres. The gray matter was decorticated and the ACa-ACp was exposed. The ACa and ACp tracts were demonstrated using a high-spatial-resolution DTI with a 3T magnetic resonance unit in 13 cases.

RESULTS

Using both techniques showed that the AC has complex interconnections with large areas of the frontal (olfactory tubercles, anterior olfactory nucleus, olfactory bulb, and the orbital gyri), temporal (amygdaloidal nuclei, temporal and perirhinal cortex), and occipital (visual cortex) lobes. The ACp makes up the major component of the AC and is composed of temporal and occipital fibers. We observed that these fibers do not make a distinct bundle; the temporal fibers joined the uncinate fasciculus and the occipital fibers joined the sagittal striatum to reach their targets.

CONCLUSIONS

Being aware of the course of the AC is important during transcallosal and interforniceal approaches to the third ventricle tumors and temporal lobe epilepsy surgery. The intermingling fibers of the AC can provide a better understanding of the unexplained deficit that may occur during regional surgery.

The relationship between consciousness and the ascending reticular activating system in patients with traumatic brain injury

Background

We investigated the relationship between consciousness and the ascending reticular activating system (ARAS) by using diffusion tensor tractography (DTT) in patients with traumatic brain injury (TBI).

Methods

Twenty-six patients with TBI and 13 healthy control subjects were recruited for this study. Glasgow Coma Scale (GCS) scores were used for evaluation of subject consciousness state at the chronic stage of TBI (at DTT scanning), According to the GCS score, the patient group was divided into two subgroups: A (14 patients;impaired consciousness: GCS score < 15, and B (12 patients;intact consciousness;GCS score = 15). Fractional anisotropy (FA) and tract volume (TV) values were assessed in the lower dorsal and upper ARAS.

Results

The FA values of the lower dorsal ARAS and the upper ARAS in patient subgroup A were significantly lower than those in patient subgroup B and the control group(p <  0.05). However, the FA and TV values for the lower dorsal ARAS and the upper ARAS were not significantly different between patient subgroup B and the control group(p > 0.05). The FA value of the lower dorsal ARAS(r = 0.473,p <  0.05) and the TV of upper ARAS(r = 0.484,p <  0.05) had moderate positive correlations with the GCS score. The FA value of the upper ARAS had a strong positive correlation with the GCS score of the patient group(r = 0.780,p <  0.05).

Conclusions

We detected a close relationship between consciousness at the chronic stage of TBI and injuries of the lower dorsal and upper ARAS (especially, the upper ARAS) in patients who showed impaired consciousness at the onset of TBI. We believe that our results can be useful during the development of therapeutic strategies for patients with impaired consciousness following TBI.

Trial registration

YUMC 2019–06–032-003. Retrospectively registered 06 Jun 2020.

Magnetic resonance-guided focused ultrasound ablation of hypothalamic hamartoma as a disconnection surgery: a case report

We report the case of a patient with hypothalamic hamartoma (HH) who was successfully treated with magnetic resonance-guided focused ultrasound (MRgFUS) for ablation as a disconnection surgery. A 26-year-old man with gelastic epilepsy had been diagnosed with HH at 3 years of age, and antiepileptic drugs were administered due to worsening episodes. Magnetic resonance imaging showed a sessile parahypothalamic hamartoma and MRgFUS ablation was performed, creating an oval-shaped lesion at the boundary area of the HH. Dramatic improvements in seizure symptoms were noted, and he was seizure-free on decreased antiepileptic drugs without any adverse events over the 1-year follow-up period.

Dysphagia prognosis prediction via corticobulbar tract assessment in lateral medullary infarction: a diffusion tensor tractography study

We investigated the capacity for dysphagia prognosis prediction using diffusion tensor tractography (DTT) to assess the state of the corticobulbar tract (CBT) during the initial period following lateral medullary infarction (LMI). Twenty patients with LMI and 20 control subjects were recruited for this study. The patients were classified into two subgroups: subgroup A (16 patients with nasogastric tube required for six months or less after LMI onset) and subgroup B (4 patients with nasogastric tube required for more than six months after onset). DTT was used to reconstruct the CBTs of each patient and control subject, and the fractional anisotropy (FA) and tract volume (TV) measurements were obtained. In the affected hemisphere, the FA value of the CBT was significantly lower in subgroup B than in subgroup A and the control group (p < 0.05), with no significant difference between subgroup A and the control group. In the affected and unaffected hemispheres, the TV values of CBT in subgroups A and B were lower than those of the control group (p < 0.05), with no significant difference between subgroups A and B. In addition, among the four patients of subgroup B, reconstruction of the CBT was not possible in three patients, and the remaining patients exhibited on old lesion in the corona radiate involving descending pathway of the CBT in the affected hemisphere. We found that the injury severity of the CBT in the affected hemisphere appeared to be related to a poor dysphagia prognosis following LMI. Our results suggest that evaluation of the CBT state during the early post-LMI could be useful for dysphagia prognosis prediction.

Injury of Corticospinal tract and Corticoreticular pathway caused by high-voltage electrical shock: a case report

Background

We imaged the corticospinal tract (CST) and corticoreticular pathway (CRP) using diffusion tensor tractography (DTT) to evaluate the cause of muscle weakness in a patient who was exposed to high-voltage electricity.

Case presentation

A 39-year-old man presented with quadriparesis after high-voltage electrical shock from power lines while working about 5.8 years ago. The electrical current entered through the left hand and exited through the occipital area of the head. The degree of weakness on bilateral upper and lower extremities was 3–4 on the Medical Research Council strength scale. Diffusion tensor imaging (DTI) was performed 5.8 years after onset. The CST and CRP were depicted by placing two regions of interest for each neural tract on the two-dimensional fractional anisotropy color map. DTT of the DTI scan showed that the bilateral CST and CRP were thinned compared to those of the healthy control subject. On the nerve conduction test, abnormal findings suggesting peripheral nerve lesion were not observed. Therefore, injury of bilateral CST and CRP seems to have contributed to our patient’s weakness after the electrical shock.

Conclusion

Depiction of neural tracts in the brain using DTT can assist in the accurate and detailed evaluation of the cause of neural deficit after electrical injury.

3-dimensional computer graphics model elucidating involvement of intraparenchymal venous malformation in trigeminal nucleus of brachium pontis with intractable trigeminal neuralgia

Venous malformation (VM) in the posterior cranial fossa occasionally cause trigeminal neuralgia (TN), which were treated with microvascular decompression of its drainer, whereas it was effective only in the limited cases, and its pathological mechanism causing TN is controversial. A 72-year-old man had a 20-year history of typical but severe TN in his left face. Without radiographic evidence of vascular compression on the root entry zone (REZ) of the trigeminal nerve, he underwent stereotactic radiosurgery in previous hospital, resulting in only temporary improvement. On T1-wighted magnetic resonance image with enhancement, the left trigeminal nerve was focally enhanced, which was typical finding after high dose irradiation for TN. Simultaneously, it disclosed small "caput medusa" within the pontine tegmentum, indicated existence of VM in brachium pontis. A 3-dimensional computer graphics model created by fusion of magnetic resonance angiography, diffusion tensor tractography, and fast imaging employing steady-state acquisition elucidated VM was located in the trigeminal nucleus of brachium pontis, which will be very useful for understanding the anatomic correlation of VM and pontine trigeminal nucleus. Since there was no vascular compression at the REZ of the trigeminal nerve, microvascular decompression was not indicated. With minimum dose of gabapentine and carbamazepin, his facial pain completely disappeared and controlled for more than 5 years.

Abdominal pain due to the spinothalamic tract injury in patients with mild traumatic brain injury: a case report

Background

We report on a patient with a mild traumatic brain injury (TBI) who developed abdominal pain due to spinothalamic tract (STT) injuries revealed by diffusion tensor tractography (DTT).

Case presentation

A 53-year-old female patient suffered head trauma resulting from a backward fall. While bathing at a public bathhouse, she fell backward and struck the occipital area of her head against the floor. After the head trauma, she experienced pain in the abdomen and in both hands and feet. She underwent evaluations including conventional brain MRI, abdominal and pelvic ultrasonography, and stomach and intestine endoscopy. No abnormality was observed in her brain or abdomen. In addition, her abdominal pain had not been relieved by medical management. When she came to our hospital 4 years after the head trauma, her pain characteristics and severity were as follows: intermittent pain without allodynia or hyperalgesia; squeezing and warm creeping-like pain in the abdomen (visual analog scale score: 7); tingling pain in both hands and feet (visual analog scale score: 7). She was prescribed pregabalin and gabapentin, and her abdominal and limb pain was well-controlled at a tolerable level. On DTT 4 years after head trauma, the upper portion of the spinothalamic tracts (STTs) in both hemispheres showed partial tearing.

Discussion and conclusions

Injury of the STT was demonstrated by using DTT in a patient who showed abdominal pain that was refractory to medical management following mild TBI. Our results suggest that central pain due to STT injury might be suspected in patients with abdominal pain that is refractory to medical management following TBI.

Prognostic Prediction of Dysphagia by Analyzing the Corticobulbar Tract in the Early Stage of Intracerebral Hemorrhage

We investigated the predictive value of the corticobulbar tract (CBT) for dysphagia using diffusion tensor tractography in the early stage of intracerebral hemorrhage (ICH) for dysphagia. Forty-two patients with spontaneous ICH ± intraventricular hemorrhage (IVH) and 22 control subjects were recruited. The patients were classified into three groups: group A-could remove nasogastric tube (NGT) in the acute stage of ICH, group B-could remove NGT within 6 months after onset, and group C-could not remove NGT until 6 months after onset. The CBT were reconstructed, and fractional anisotropy (FA) and tract volume (TV) values were determined. The FA of the CBT in the affected hemisphere in group A was lower than in the control group (p < 0.05). The FA and TV of the CBT in the affected hemisphere in group B were lower than those in the control group (p < 0.05). In group C, the FA and TV in the affected hemisphere and unaffected hemispheres were lower than in the control group (p < 0.05). The TV of the CBT in the affected hemisphere in group B showed a moderate negative correlation with the length of time until NGT removal (r = 0.430, p < 0.05). We found that patients with CBT injuries in both hemispheres were not able to remove the NGT until 6 months after onset, whereas patients who were injured only in the affected hemisphere were able to remove NGT within 6 months of onset. The severity of injury to the CBT in the affected hemisphere appeared to be related to the length of time until NGT removal.

Effect of repetitive transcranial magnetic stimulation on the ascending reticular activating system in a patient with disorder of consciousness: a case report

Background

We report on a stroke patient with disorder of consciousness (DOC) who underwent repetitive transcranial magnetic stimulation (rTMS) and showed recovery of an injured upper ascending reticular activating system (ARAS) injury, which was demonstrated by using serial diffusion tensor tractography (DTT).

Case presentation

A 45-year-old male patient was diagnosed as subarachnoid and intracerebral hemorrhages in the left fronto-parieto-temporal lobes. At 5 months after onset, the patient exhibited a persistent vegetative state, with a Coma Recovery Scale-Revised (CRS-R) score of 4. He underwent comprehensive rehabilitative therapy that included drugs for recovery of impaired consciousness and rTMS of the right dorsolateral prefrontal lobe. He recovered to a minimally conscious state (CRS-R: 13) at 7 months after onset and was transferred to a local rehabilitation hospital where he underwent similar rehabilitation but without rTMS. At 9 months after onset, his CRS-R score remained at 13. He was then readmitted to our hospital and underwent rehabilitation with rTMS until 10 months after onset. His CRS-R remained at 13, but his higher cognition had improved. The tract volume (TV) of the neural tract in the right prefrontal lobe in the upper ARAS on the 7-month DTT was higher than that on the 5-month DTT. However, compared to the 7-month DTT, the right prefrontal lobe TV was lower on the 9-month DTT. On the 10-month DTT, the TV of that neural tract had again increased.

Conclusions

Increases in neural TV in the right prefrontal lobe of the upper ARAS that were associated with the periods of rTMS application were demonstrated in a stroke patient with DOC.

Anatomical Characteristics of Thalamus-Cortical Sensory Tract in the Human Brain Using Diffusion Tensor Tractography at 3.0 Tesla Scanner

BACKGROUND:

Our knowledge about characteristics of the thalamocortical tract (THT) according to the cerebral origin is still few of studies about this structure on Vietnamese.

AIM:

Here, we aim to characterise the morphology of the thalamocortical tract in the human brain using diffusion tensor tractography (DTT) at 3.0 tesla scanner.

METHODS:

Fifty healthy subjects have enrolled in this study. Reconstructed images of the thalamocortical tract in the human brain were built using DTT at 3.0 tesla scanner.

RESULTS:

The median length of the right thalamocortical tract was 130.64 mm, and the left THT was 123.14 mm, and an average of two sides was 126.34 mm. The difference between the two sides was statically significance (p < 0.001). The median fibre number of the right THT was 401.50, and the left THT was 315.00, and an average of two sides was 365.50. There was a diverse branch of THT: two branches (5%); three branches (25%); four branches (42%); five branches (16%); six branches (12%); in which branched contralateral for the right was 50%, and for the left was 50%.

CONCLUSION:

Using the DTI and 3D image reconstruction techniques allow to build the image of sensory THT intuitively and accurately, which helps to identify the morphological characteristic of the thalamocortical tract of healthy people without invasive effects.

Fiber dissection and 3-tesla diffusion tensor tractography of the superior cerebellar peduncle in the human brain: emphasize on the cerebello-hypthalamic fibers

Experimental studies in various species using tract-tracing techniques showed clear evidence of the presence of cerebello-hypothalamic projections. However, these connections were not clearly described in humans. In the present study we aimed to describe the direct cerebello-hypothalamic connections within the superior cerebellar peduncle (SCP) using fiber dissection techniques on cadaveric brains and diffusion tensor tractography (DTI) in healthy adults. Fiber dissection was performed in a stepwise manner from lateral to medial on 6 cerebral hemispheres. The gray matter was decorticate and fiber tracts were revealed. The SCP was exposed and the fibers were traced distally using wooden spatulas. The MRI examinations were performed in seven cases using 3-tesla 3T unit. The direct cerebello-hyothalamic pathways were exposed using high-spatial-resolution DTI. The present study using both fiber dissection and DTI in adult human showed direct cerebello-hypothalamic fibers within the SCP. The SCP fibers course anterolateral to the cerebral aqueduct reaching the level of the red nucleus of the midbrain. The majority of the fibers crosses over and reached the contralateral diencephalic structures and some of these fibers terminated at the contralateral anterior hypothalamic area. Some of the uncrossed SCP fibers reached the ipsilateral diencephalic structures and terminated at the ipsilateral posterior hypothalamic area. We further reported the close relationship of the SCP with the MCP, lateral lemniscus, red nucleus and substantia nigra. In the DTI evaluations of the SCP we exposed unilateral left cerebello-hypothalamic fibers in five cases and bilateral cerebello-hypothalamic fibers in two cases. The present study demonstrates the direct cerebello-hypothalamic connections within the SCP for the first time using fiber dissection and DTI technique in the human brain. The detailed knowledge of the cerebello-hypothalamic fibers can outline the unexplained deficit that may occur during regional surgery.

Diagnostic Approach to Traumatic Axonal Injury of the Spinothalamic Tract in Individual Patients with Mild Traumatic Brain Injury

Objectives: We investigated an approach for the diagnosis of traumatic axonal injury (TAI) of the spinothalamic tract (STT) that was based on diffusion tensor tractography (DTT) results and a statistical comparison of individual patients who showed central pain following mild traumatic brain injury (mTBI) with the control group. Methods: Five right-handed female patients in their forties and with central pain following mTBI and 12 age-, sex-, and handedness-matched healthy control subjects were recruited. After DTT reconstruction of the STT, we analyzed the STT in terms of three DTT parameters (fractional anisotropy (FA), mean diffusivity (MD), and fiber number (FN)) and its configuration (narrowing and tearing). To assess narrowing, we determined the area of the STT on an axial slice of the subcortical white matter. Results: the FN values were significantly lower in at least one hemisphere of each patient when compared to those of the control subjects (p < 0.05). Significant decrements from the STT area in the control group were observed in at least one hemisphere of each patient (p < 0.05). Regarding configurational analysis, the STT showed narrowing and/or partial tearing in at least one hemisphere of each of the five patients. Conclusions: Herein, we demonstrate a DTT-based approach for the diagnosis of TAI of the STT. The approach involves a statistical comparison between DTT parameters of individual patients who show central pain following mTBI and those of an age-, gender-, and handedness-matched control group. We think that the method described in this study can be useful in the diagnosis of TAI of the STT in individual mTBI patients.

Limited positive predictive value of diffusion tensor tractography in determining clinically relevant white matter damage in brain stem cavernous malformations: A retrospective study in a single center surgical cohort

PURPOSE

Diffusion tensor tractography (DTT) might reflect the postoperative clinical outcome of the patients with brain stem (BS) tumors correlating well with the neurological symptoms, but cavernous malformation (CM) is a hemorrhagic tumor prone to artifacts that may limit DTT. We set out to determine the correlation of DTT findings with the neurological examination before and after surgical resection in patients with BSCMs.

MATERIALS AND METHODS

DTT findings were evaluated bilaterally for fiber tract displacement or deviation, deformation and interruption in every patient before and after the surgery. Neurological examination was performed at admission, discharge and outpatient follow-up visit. The sensitivity, specificity, positive and negative predictive values of DTT were calculated both pre- and post-operatively.

RESULTS

There were 25 patients (9 men 16 women) with a mean age of 39.5±13.9 years. The mean size of the CMs was 6909±8374mm³ (range: 180-38,220mm³) The mean follow-up time was 42.7±23.2 months (range: 8 to 112 months). Preoperatively, the sensitivity, specificity, positive and negative predictive values of DTT for corticospinal tracts (CST) and medial lemnisci (ML) were 100%, 60%, 38.4%, 100% and 87.5%, 11.7%, 31.8%, 66.6%, respectively. Postoperatively, the sensitivity, specificity, positive and negative predictive values of DTT for CSTs and ML were 100%, 64.7%, 40%, 100% and 100%, 0%, 33.3%, 66.6%, respectively.

CONCLUSION

Positive findings on DTT such as fiber tract deviation, deformation, disruption or interruption should be taken cautiously before drawing conclusions of a clinically relevant damage of white matter tracts.

Alterations of white matter network in patients with left and right non-lesional temporal lobe epilepsy

OBJECTIVES

The goal of this study was to investigate alterations of white matter (WM) network in patients with left non-lesional temporal lobe epilepsy (nl-TLE) and right nl-TLE to assess the relationship between the white matter network properties and clinical parameters.

METHODS

T1 magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) were acquired for 45 participants, including 30 nl-TLE patients (13 left, 17 right) and 15 healthy controls. Diffusion tensor tractography was computed to model the WM structural network. The topologic properties of the WM network were obtained by graph theoretical analysis, and the between-group differences in global and nodal properties of the WM network were examined by network-based statistical analysis (NBS). The relationship between WM network properties and clinical parameters was assessed by Pearson's correlation analysis.

RESULTS

NBS results indicated that patients with left and right nl-TLE experienced distinct changes of WM nodal and global network properties compared with HCs. Positive correlation coefficients were found in several regions. The structural disruptions of networks in the two nl-TLE groups were observed to be different in distribution and severity.

CONCLUSIONS

This study provides evidence for changes of the WM network topological properties and structural connectivity in nl-TLE patients, which provide useful insights for the understanding of disease mechanisms of TLE and improving treatment outcomes for nl-TLE.

KEY POINTS

• This study aims to investigate alterations of white matter (WM) network in patients with non-lesional temporal lobe epilepsy (nl-TLE). • Network-based statistical analysis results indicated that patients with left and right nl-TLE experienced distinct changes of WM nodal and global network properties compared with healthy controls. • This study provides useful insights for the understanding of disease mechanisms of TLE and improving treatment outcomes for nl-TLE.

Difference in the Ascending Reticular Activating System Injury Between Mild Traumatic Brain Injury and Cerebral Concussion

Introduction

We investigated differences in the ascending reticular activating system (ARAS) injuries between patients with mild traumatic brain injury (mTBI) and cerebral concussion by using diffusion tensor tractography (DTT).

Methods

Thirty-one patients with mTBI, 29 patients with concussion, and 30 control subjects were recruited. We used DTT to reconstruct the lower ventral and dorsal ARAS, and the upper ARAS. The fractional anisotropy (FA) value and the fiber number (FN) of the lower ventral and dorsal ARAS, and the upper ARAS were determined.

Results

Significant differences were observed in the FA values of the lower ventral and dorsal ARAS on both sides between the mTBI and control groups and between the concussion and control groups (p < 0.05). The FN value was significantly different in the lower ventral ARAS on both sides between the concussion and control groups and between the mTBI and concussion groups (p < 0.05).

Conclusion

Both the mTBI and concussion patients suffered injuries in the lower ventral and dorsal ARAS, with the concussion patients exhibiting more severe injury in the ventral ARAS than that in the mTBI patients. These results suggest that the terms mTBI and concussion should be used differentially, even though they have used interchangeably for a long time.

Injury of auditory radiation and sensorineural hearing loss from mild traumatic brain injury

OBJECTIVES

We report on a patient with sensorineural hearing loss from injury of the auditory radiation following mild TBI, diagnosed by diffusion tensor tractography (DTT).

METHOD

A 35-year-old female patient suffered head trauma. While walking in a crosswalk, her left lumbar area was hit by a turning car and she fell to the ground. She was pulled behind the car for several meters while her occipital area repeatedly hit the ground. She complained that she began to feel hearing impairment approximately two weeks after the head trauma, that aggravated over time. Approximately 1.5 years after head trauma, when she visited a university hospital for evaluation of the brain, she complained of severe hearing impairment. To characterize the patient's hearing loss, pure tone audiometry was evaluated in a sound proof room to screen her hearing status for the frequencies 250-8000 Hz. A pure tone threshold in the range of 41-60 dB HL was considered moderate sensorineural hearing loss and 61-80 dB HL severe. However, no abnormality was observed in either ear on physical examination. The patient was diagnosed with bilateral moderate sensorineural hearing loss.

RESULTS

On 1.5 year DTT, the auditory radiation was narrowed in both hemispheres.

CONCLUSION

Neural injury of the auditory radiation was demonstrated in a patient with sensorineural hearing loss following mild TBI, using DTT.

Diffusion parameters of the core of cingulum are associated with age-related ventricular enlargement: a diffusion tensor tractography study

PURPOSE

To evaluate the influence of the size of lateral ventricles on diffusion parameters of the normal cingulate bundle.

METHODS

Eighty normal subjects (17-55 years) underwent MRI at 3 T including diffusion tensor imaging. Superior (SC) and inferior (IC) cingulum were analyzed separately. Mean diffusivity (MD_0.30) and fractional anisotropy (FA_0.30) were measured by tractography at FA threshold 0.30; further diffusion parameters were analyzed by tractography-based core analysis in volumes of 3.0 cm³/1.5 cm³. The diffusion parameters were correlated with corresponding cross-sectional coronal areas of lateral ventricles. The analysis was performed also separately for young (17-34) and middle-aged (35-55) subjects.

RESULTS

FA_0.30 values did not correlate with ventricular size, but there was a weak negative correlation (r = - 0.225) between MD_0.30 of SC and ventricular size. In all controls and in the older age group, ventricular size correlated positively with core FA of SC (r = 0.262/r = 0.391) and negatively with mean diffusivity (r = - 0.324/r = - 0.303) and radial diffusivity (λ₂: r = - 0.238/r = - 0.277; λ₃: r = - 0.353/r = - 0.424) of the core of SC. In the younger age group, only the mean diffusivity of SC correlated with ventricular size (r = - 0.273). Ventricular size was not associated with axial diffusivity. The core parameters of IC did not correlate with ventricular size.

CONCLUSION

Radial diffusivity of the core of cingulum decreases in age-dependent ventricular enlargement, which can be related to tissue compaction with stretching of axons and diminution of extracellular spaces. The phenomenon, which is reverse to the assumed effect of age-related myelin loss, can influence on DTI parameters in middle-aged subjects.

The Ipsilateral Vestibulothalamic Tract in the Human Brain

Although there are a few studies of portions of the vestibular system such as the vestibulocerebellar tract and the neural connectivity of the vestibular nuclei (VN), no study of the ipsilateral vestibulothalamic tract (VTT) (originating from the VN and mainly connecting to the lateral thalami nuclei) has been reported. In the current study, using diffusion tensor tractography (DTT), we investigate the reconstruction method and characteristics of the ipsilateral VTT in normal subjects. Thirty-three subjects were recruited for this study. For the ipsilateral VTT, the seed region of interest (ROI) was placed on the VN, which was isolated on the FA map using adjacent structures as follows: the reticular formation (anterior boundary), posterior margin of medulla and pons (posterior boundary), medial lemniscus (medial boundary) and restiform body (lateral boundary). The target ROI was placed at the lateral thalamic nuclei using known anatomical locations. The DTT parameters of the ipsilateral VTT were measured. The ipsilateral VTTs that originated from the vestibular nuclei ascended postero-laterally to the upper pons and antero-medially to the upper midbrain via the medial longitudinal fasciculus, and terminated the lateral thalamic nuclei. No significant differences were observed in DTT parameters of the ipsilateral VTT between the right and left hemispheres (p > 0.05). Using DTT, we reconstructed the ipsilateral VTT and observed the anatomical characteristics of the ipsilateral VTT in normal subjects. We believe that the methodology and results in this study could be helpful to researchers and clinicians in this field.

Piriformis muscle syndrome with assessment of sciatic nerve using diffusion tensor imaging and tractography: a case report

Piriformis muscle syndrome (PMS) is difficult to diagnose by objective evaluation of sciatic nerve injury. Here we report a case of PMS diagnosed by diffusion tensor imaging (DTI) and tractography of the sciatic nerve, which can assess and visualize the extent of nerve injury. The patient was a 53-year-old man with a 2-year history of continuous pain and numbness in the left leg. His symptoms worsened when sitting. Physical examination, including sensorimotor neurologic tests, the deep tendon reflex test, and the straight leg raise test, revealed no specific findings. The hip flexion adduction and internal rotation test and resisted contraction maneuvers for the piriformis muscle were positive. There were no abnormal findings on magnetic resonance imaging (MRI) of the lumbar spine. The transverse diameter of piriformis muscle was slightly thicker in affected side on MRI of the pelvis. A single DTI sequence was performed during MRI of the pelvis. Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the sciatic nerve were quantified at three levels using the fiber-tracking method. FA values were significantly lower and ADC values were significantly higher distal to the piriformis muscle. We performed endoscopic-assisted resection of the piriformis tendon. Intraoperatively, the motor-evoked potentials in the left gastrocnemius were improved by resection of the piriformis tendon. The patient's symptoms improved immediately after surgery. There was no significant difference in FA or ADC at any level between the affected side and the unaffected side 3 months postoperatively. MRI-DTI may aid the diagnosis of PMS.

Injury of ascending reticular activating system associated with delayed post-hypoxic leukoencephalopathy: a case report

Background

Delayed post-hypoxic leukoencephalopathy (DPHL) is a demyelinating syndrome characterized by neurological relapse after an initial recovery from hypoxic brain injury. We describe a patient with impaired consciousness following DPHL, concurrent with injury of the ascending reticular activating system (ARAS) shown using diffusion tensor tractography (DTT).

Case presentation

A 50-year-old male patient was in a drowsy mental state after exposure to carbon monoxide (CO) for about ten hours. About a day after the CO exposure, his mental state recovered to an alert condition. However, his consciousness deteriorated to drowsy 24 days after the exposure and worsened to a semi-coma state at 26 days after onset. When he started rehabilitation six weeks after the CO exposure, he had impaired consciousness, with a Glasgow Coma Scale score of 8 and a Coma Recovery Scale-Revised score of 8. On 6-week DTT, decreased neural connectivity of the upper ARAS between the intralaminar thalamic nucleus and the cerebral cortex was observed in both frontal cortices, basal forebrains, basal ganglia and thalami. The lower dorsal ARAS was not reconstructed on the right side, and was thin on the left side. The lower ventral ARAS was not reconstructed on either side.

Conclusions

Using DTT, we demonstrated injury of the ARAS in a patient with impaired consciousness following DPHL. Our result suggests that injury of the ARAS is a plausible pathogenetic mechanism of impaired consciousness in patients with DPHL.

Relationship Between Perisylvian Essential Language Sites and Arcuate Fasciculus in the Left Hemisphere of Healthy Adults

Essential language sites and the arcuate fasciculus (AF) have been extensively researched. However, the relationship between them remains insufficiently studied, especially in healthy people. Navigated transcranial magnetic stimulation (nTMS) is increasingly used in language mapping. While enjoying the advantage of non-invasiveness, it is also capable of inducing a virtual lesion in the brain. Thus, it offers the possibility of using the virtual-lesion method to study the healthy brain. This study combined nTMS and diffusion tensor imaging (DTI) tractography to investigate the relationship between essential language sites and the AF in 30 healthy right-handed volunteers. A total of 143 essential language sites were identified using nTMS, and a total of 175 AF terminations were identified using DTI tractography. Sixty-six sites had a direct correlation with the AF, accounting for 46% of the total essential language sites. Forty-seven AF terminations harbored essential language sites, accounting for 27% of the total AF terminations. Upon data rendering to the cortical parcellation system, a region-related heterogeneity of the correlation rate was found. This study provides the first data on the relationship between essential language sites and the AF in healthy adults.

Diffusion tensor imaging and tractography of the sciatic nerve: assessment of fractional anisotropy and apparent diffusion coefficient values relative to the piriformis muscle, a preliminary study

OBJECTIVE

Piriformis muscle syndrome (PMS) is underdiagnosed. To evaluate the potential of diffusion tensor imaging and diffusion tensor tractography as innovative tools for the diagnosis of PMS by functional assessment of the sciatic nerve, the aims of this study are to assess the reproducibility and to evaluate the changes in the parameters at levels proximal and distal to the piriformis.

MATERIALS AND METHODS

Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the sciatic nerve at three levels were quantified twice each by two examiners using the fiber-tracking method. In the first part of the study, laterality and reproducibility were evaluated using intraclass correlation coefficients (ICC) in ten healthy volunteers. In the second part of the study, the healthy side and symptomatic side were assessed in ten consecutive patients with sciatica. There were three patients with no findings on lumbar magnetic resonance imaging (MRI).

RESULTS

There was no laterality in either FA or ADC values in asymptomatic patients at any level. The mean intra-rater ICC was 0.90 and the mean inter-rater ICC was 0.87. FA was significantly lower and ADC significantly higher on the symptomatic side at each level in patients with sciatica. In the three sciatica patients with no findings on lumbar MRI, FA was significantly lower and ADC was significantly higher only at levels distal to the piriformis. These patients experienced full pain relief after ultrasound-guided injection of local anesthesia.

CONCLUSIONS

Diffusion tensor imaging and diffusion tensor tractography might be innovative tools for the diagnosis of PMS.

Differential involvement of corticospinal tract (CST) fibers in UMN-predominant ALS patients with or without CST hyperintensity: A diffusion tensor tractography study

Diagnosis of amyotrophic lateral sclerosis (ALS) depends on clinical evidence of combined upper motor neuron (UMN) and lower motor neuron (LMN) degeneration, although ALS patients can present with features predominantly of one or the other. Some UMN-predominant patients show hyperintense signal along the intracranial corticospinal tract (CST) on T2- and proton density (PD)-weighted images (ALS-CST +), and appear to have faster disease progression when compared to those without CST hyperintensity (ALS-CST -). The reason for this is unknown. We hypothesized that diffusion tensor tractography (DTT) would reveal differences in DTI abnormalities along the intracranial CST between these two patient subgroups. Clinical DTI scans were obtained at 1.5T in 14 neurologic controls and 45 ALS patients categorized into two UMN phenotypes based on clinical measures and MRI. DTT was used to quantitatively assess the CST in control and ALS groups. DTT revealed subcortical loss ('truncation') of virtual motor CST fibers (presumably) projecting from the precentral gyrus (PrG) in ALS patients but not in controls; in contrast, virtual fibers (presumably) projecting to the adjacent postcentral gyrus (PoG) were spared. No significant differences in virtual CST fiber length were observed between controls and ALS patients. However, the frequency of CST truncation was significantly higher in the ALS-CST + subgroup (9 of 21) than in the ALS-CST - subgroup (4 of 24; p = 0.049), suggesting this finding could differentiate these ALS subgroups. Also, because virtual CST truncation occurred only in the ALS patient group and not in the control group (p = 0.018), this DTT finding could prove to be a diagnostic biomarker of ALS. Significantly shorter disease duration and faster disease progression rate were observed in ALS patients with CST fiber truncation than in those without (p < 0.05). DTI metrics of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were also determined in four regions of interest (ROIs) along the CST, namely: cerebral peduncle (CP), posterior limb of internal capsule (PLIC), centrum semiovale at top of lateral ventricle (CSoLV) and subcortical to primary motor cortex (subPMC). Of note, FA values along the left hemisphere virtual CST tract were significantly different between controls and ALS-CST + patients (p < 0.05) only at the PLIC level, but not at the CSoLV or subPMC level. Also, no significant differences in FA values were observed between ALS subgroups or between control and ALS-CST - groups (p > 0.05) in any of the ROIs. In addition, comparing FA values between ALS patients with CST truncation and those without in the aforementioned four ROIs, revealed no significant differences in either hemisphere. However, visual evaluation of DTT was able to identify UMN degeneration in patients with ALS, particularly in those with a more aggressive clinical disease course and possibly different pathologic processes.

Axial MR diffusion tensor imaging and tractography in clinical diagnosed and pathology confirmed cervical spinal cord astrocytoma

OBJECTIVE

To evaluate the diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) features of cervical spinal cord astrocytoma.

METHODS

Eleven patients with cervical spinal cord astrocytomas and 10 healthy volunteers were recruited in this study. Conventional magnetic resonance imaging (MRI) and axial DTI were performed on a 3.0T MRI system. Apparent diffusion coefficient (ADC), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) values for the lesions were measured. DTT was performed using the principal diffusion direction method.

RESULTS

ADC values of the lesions and the normal-appearing tissue around the tumour (NATAT) on T2-weighted imaging (T2WI) increased. The ADC values of the lesions were higher. The FA values of the lesions and the NATAT decreased significantly, with the lesions having lower FA values. The RD value (1.36±0.49) of the tumours was significantly higher than those found in the healthy controls, but similar for the AD value (1.84±0.56). There were no differences in ADC or FA values between lesions and NATAT in McCormick Type I vs. Type II patients. Based on the DTT, 7 patients with solid mass tumours were classified as Type I. One patient with a solid mass, 2 patients with cystic degeneration inside the lesions, and 1 patient with a cyst around the mass were classified as Type II.

CONCLUSIONS

FA values of the cervical spinal cord astrocytoma decreased, but the ADC values increased. DTI was sensitive for the evaluation of pathological changes that could not be visualized on T2WI. Our preliminary study indicates that DTT can be used to guide operation planning, and that axial images of DTT may be more valuable.

Limb-kinetic apraxia due to injury of corticofugal tracts from secondary motor area in patients with corona radiata infarct

Limb-kinetic apraxia (LKA) is defined as an execution disorder of movements, resulting from injury of the corticofugal tract (CFT) from the secondary motor area. Diagnosis of LKA is difficult because it is made by clinical observation of movements. In this study, using diffusion tensor tractography (DTT), we attempted to investigate injury of the CFT from the secondary motor area in patients with corona radiata infarct. Twenty patients with corona radiata infarct were recruited. A probabilistic tractography method was used in fiber tracking for reconstruction of the corticospinal tract (CST) and CFT. Fractional anisotropy (FA), mean diffusivity, and tract volume of the CSTs and CFTs from the dorsal premotor cortex (dPMC) and supplementary motor area (SMA) were measured. In the affected hemisphere, FA values of the CST from the precentral hand knob and the CFT from the dPMC were significantly decreased compared with those of the unaffected hemisphere (p < 0.05). The tract volumes of the CST from the precentral hand knob and the CFTs from the dPMC and SMA in the affected hemisphere were also significantly decreased compared with those of the unaffected hemisphere (p < 0.05). We demonstrated concurrent injury of the CFTs from the secondary motor area along with injury of the CST in patients with corona radiata infarct, using DTT. Our results suggest that LKA ascribed to injury of the CFTs from the secondary motor area could be accompanied by injury of the CST ascribed to the corona radiata infarct.

Prediction of upper extremity motor recovery after subacute intracerebral hemorrhage through diffusion tensor imaging: a systematic review and meta-analysis

INTRODUCTION

Early assessment of the pyramidal tracts is important for intracerebral hemorrhage (ICH) patients in order to decide the optimal treatment or to assess appropriate rehabilitation strategies, and management of patient expectations and goals. The purpose of this study was to systematically review and summarize the current available literature on the value of Fractional Anisotropy (FA) parameter of the diffusion tensor imaging (DTI) in predicting upper extremity (UE) motor recovery after subacute ICH.

METHODS

PubMed, EMBASE, MEDLINE, Google Scholar, and Cochrane CENTRAL searches were conducted from 1 January 1950 to 31 March 2016 which were supplemented with relevant articles identified in the references. Pooled estimate using correlation between DTI parameter FA and UE motor recovery was done using comprehensive meta-analysis software.

RESULTS

Out of 97 citations, only eight studies met the criteria for inclusion in the systematic review and six studies were included in the meta-analysis. A random effects model revealed that DTI parameter FA is a significant predictor for UE motor recovery after subacute ICH (correlation coefficient = 0.56; 95 % confidence interval 0.44 to 0.65, P value <0.001). However, moderate heterogeneity was observed between the studies (Tau-squared = 0.28, I-squared = 70.3).

CONCLUSION

The studies reported so far on correlation between FA parameter of DTI and UE motor recovery in ICH patients are few with small sample sizes. This meta-analysis suggests a strong correlation between DTI parameter FA and UE motor recovery in ICH patients. Further well-designed prospective studies embedded with larger sample size are needed to confirm these findings.

Injury of the Arcuate Fasciculus in the Nondominant Hemisphere by Subfalcine Herniation in Patients with Intracerebral Hemorrhage : Two Case Reports and Literature Review

Using diffusion tensor tractography (DTT), we demonstrated injury of the arcuate fasciculus (AF) in the nondominant hemisphere in two patients who showed subfalcine herniation after intracerebral hemorrhage (ICH) in the dominant hemisphere. Two patients (patient 1 and patient 2) with ICH and six age-matched control patients who have ICH on the left corona radiata and basal ganglia without subfalcine herniation were recruited for this study. DTT was performed at one month after onset in patient 1 and patient 2. AFs of both hemispheres in both patients were disrupted between Wernicke's and Broca's areas. The fractional anisotropy value and tract numbers of the right AFs in both patients were found to be more than two standard deviations lower than those of control patients. In contrast, the apparent diffusion coefficient value was more than two standard deviations higher than those of control patients. Using the configuration and parameters of DTT, we confirmed injury of the AF in the nondominant hemisphere in two patients with subfalcine herniation following ICH in the dominant hemisphere. Therefore, DTT would be a useful tool for detection of underlying injury of the AF in the nondominant hemisphere in patients with subfalcine herniation.

Central pain due to spinothalamic tract injury caused by indirect head trauma following a pratfall

OBJECTIVES

This study reports on patients who showed central pain due to injury of the spinothalamic tract (STT) caused by fall without direct head trauma.

DESIGN

Prospective study.

PARTICIPANTS

Two patients with mild traumatic brain injury (TBI) resulting from a fall were enrolled. Patient 1 was a 21-year-old female who had suffered a pratfall with no history of direct head trauma. She had begun to feel pain in both upper trunk and lower back and the left leg since ~ 5 days after onset: constant tingling and throbbing sensation with allodynia. Patient 2 was a 39-year-old male who had suffered a pratfall without direct head trauma. He had begun to feel pain in both arms and legs since ~ 4 days after the fall: constant tingling and pricking sensation without allodynia or hyperalgesia.

RESULTS

On diffusion tensor tractograhpy (DTT) of patient 1, partial tearing of the right STT was observed at the subcortical white matter. On DTT of patient 2, partial tearing at the subcortical white matter was observed in the right STT and partial narrowing at the subcortical white matter was observed in the left STT.

CONCLUSIONS

This study demonstrated injury of the STT in patients who suffered from central pain following a fall. The results suggest that minor indirect head trauma can cause traumatic axonal injury of the brain.

Identification of cranial nerves around trigeminal schwannomas using diffusion tensor tractography: a technical note and report of 3 cases

BACKGROUND

There are no large series studies identifying the locations of cranial nerves (CNs) around trigeminal schwannomas (TSs); however, surgically induced cranial neuropathies are commonly observed after surgeries to remove TSs. In this study, we preoperatively identified the location of CNs near TSs using diffusion tensor tractography (DTT).

METHODS

An observational study of the DTT results and intraoperative findings was performed. We preoperatively completed tractography from images of patients with TSs who received surgical therapy. The result was later validated during tumorectomy.

RESULTS

A total of three consecutive patients were involved in this study. The locations of CNs V-VIII in relation to the tumor was clearly revealed in all cases, except for CN VI in case 3.The predicted fiber tracts were in agreement with intraoperative observations.

CONCLUSIONS

In this study, preoperative DTT accurately predicted the location of the majority of the nerves of interest. This technique can be applied by surgeons to preoperatively visualize nerve arrangements.

Longitudinal study on diffusion tensor imaging and diffusion tensor tractography following spinal cord contusion injury in rats

INTRODUCTION

Diffusion tensor imaging (DTI) as a potential technology has been used in spinal cord injury (SCI) studies, but the longitudinal evaluation of DTI parameters after SCI, and the correlation between DTI parameters and locomotor outcomes need to be defined.

METHODS

Adult Wistar rats (n = 6) underwent traumatic thoracic cord contusion by an NYU impactor. DTI and Basso-Beattie-Bresnahan datasets were collected pre-SCI and 1, 3, 7, 14, and 84 days post-SCI. Diffusion tensor tractography (DTT) of the spinal cord was also generated. Fractional anisotropy (FA) and connection rate of fibers at the injury epicenter and at 5 mm rostral/caudal to the epicenter were calculated. The variations of these parameters after SCI were observed by one-way analysis of variance and the correlations between these parameters and motor function were explored by Pearson's correlation.

RESULTS

FA at the epicenter decreased most remarkably on day 1 post-SCI (from 0.780 ± 0.012 to 0.330 ± 0.015), and continued to decrease slightly by day 3 post-SCI (0.313 ± 0.015), while other parameters decreased significantly over the first 3 days after SCI. DTT showed residual fibers concentrated on ventral and ventrolateral sides of the cord. Moreover, FA at the epicenter exhibited the strongest correlation (r = 0.887, p = 0.000) with the locomotion performance.

CONCLUSION

FA was sensitive to degeneration in white matter and DTT could directly reflect the distribution of the residual white matter. Moreover, days 1 to 3 post-SCI may be the optimal time window for SCI examination and therapy.

Prediction of Upper Limb Motor Recovery after Subacute Ischemic Stroke Using Diffusion Tensor Imaging: A Systematic Review and Meta-Analysis

Early evaluation of the pyramidal tract using Diffusion Tensor Imaging (DTI) is a prerequisite to decide the optimal treatment or to assess appropriate rehabilitation. The early predictive value of DTI for assessing motor and functional recovery in ischemic stroke (IS) has yielded contradictory results. The purpose is to systematically review and summarize the current available literature on the value of Fractional Anisotropy (FA) parameter of the DTI in predicting upper limb motor recovery after sub-acute IS. MEDLINE, PubMed, EMBASE, Google Scholar and Cochrane CENTRAL searches were conducted from January 1, 1950, to July 31, 2015, which was supplemented with relevant articles identified in the references. Correlation between FA and upper limb motor recovery measure was done. Heterogeneity was examined using Higgins I-squared, Tau-squared. Summary of correlation coefficient was determined using Random Effects model. Out of 166 citations, only eleven studies met the criteria for inclusion in the systematic review and six studies were included in the meta-analysis. A random effects model revealed that DTI parameter FA is a significant predictor for upper limb motor recovery after sub-acute IS [Correlation Coefficient=0.82; 95% Confidence Interval-0.66 to 0.90, P value<0.001]. Moderate heterogeneity was observed (Tau-squared=0.12, I-squared=62.14). The studies reported so far on correlation between DTI and upper limb motor recovery are few with small sample sizes. This meta-analysis suggests strong correlation between DTI parameter FA and upper limb motor recovery. Well-designed prospective trials embedded with larger sample size are required to establish these findings.

Diffusion tensor tractography imaging in pediatric epilepsy - A systematic review

PURPOSE

Recent years brought several experimental and clinical reports applying diffusion tensor tractography imaging (DTI) of the brain in epilepsy. This study was aimed to evaluate current evidence for adding the DTI sequence to the standard diagnostic magnetic resonance imaging (MRI) protocol in pediatric epilepsy.

MATERIAL AND METHODS

Rapid and qualitative systematic review (RAE, Rapid Evidence Assessment), aggregating relevant studies from the recent 7 years. The PubMed database was hand searched for records containing terms "tractography AND epilepsy." Only studies referring to children were included; studies were rated using "final quality of evidence."

RESULTS

Out of 144 screened records, relevant 101 were aggregated and reviewed. The synthesis was based on 73 studies. Case-control clinical studies were the majority of the material and comprised 43.8% of the material. Low 'confirmability' and low 'applicability' referred to 18 and 17 articles (29.5% and 27.9%), respectively. The sufficient quality of evidence supported performing DTI in temporal lobe epilepsy, malformations of cortical development and prior to a neurosurgery of epilepsy.

CONCLUSIONS

The qualitative RAE provides an interim estimate of the clinical relevance of quickly developing diagnostic methods. Based on the critical appraisal of current knowledge, adding the DTI sequence to the standard MRI protocol may be clinically beneficial in selected patient groups with childhood temporal lobe epilepsy or as a part of planning for an epilepsy surgery.

Topographic organization of motor fibre tracts in the human brain: findings in multiple locations using magnetic resonance diffusion tensor tractography

OBJECTIVES

To identify the hand and foot fibre tracts of the corticospinal tract (CST), and to evaluate the relative locations, angles, and distances of two fibre tracts using diffusion tensor tractography (DTT).

METHODS

Twelve healthy subjects were enrolled. The regions of interests (ROIs) were drawn in the functional magnetic resonance imaging (fMRI) activation areas and pons in each subject for fibre tracking. We evaluated fibre tract distributions using distances and angles between two fibre tracts starting from the location of a hand fibre tract in multiple brain regions.

RESULTS

The measured angles and distances were 96.43-150°/2.69-9.93 mm (upper CR), 91.86-180°/1.63-7.42 mm (lower CR), 54.47-75°/0.75-4.45 mm (PLIC), and 3.65-90°/0.11-2.36 mm (pons), respectively. The distributions between CR and other sections, such as PLIC and pons, were statistically significant (p < 0.05). There were no significant differences between the upper and lower CR\ or between the PLIC and pons.

CONCLUSIONS

This study showed that the somatotopic arrangement of the hand fibre tract was located at the anterolateral portion in CR and at the anteromedial portion in PLIC and pons, based on the foot fibre. Our methods and results seem to be helpful in motor control neurological research.

KEY POINTS

• We evaluated somatotopic arrangement of CST at multiple anatomical locations. • Somatotopic arrangements and fibre tract distributions were evaluated based on hand fibre location. • Relative angles, locations, and distances between two fibres vary according to their anatomical locations.