Increased thalamocortical connectivity to the medial prefrontal cortex with recovery of impaired consciousness in a stroke patient: A case report

RATIONALE

We report a stroke patient who showed increased thalamocortical connectivity to the medial prefrontal cortex (mPFC) with recovery of impaired consciousness that was demonstrated on diffusion tensor tractography (DTT) of the ascending reticular activating system (ARAS).

PATIENTS CONCERNS

A 48-year-old male patient underwent craniectomy and hematoma removal for spontaneous intracerebral hemorrhage in the right basal ganglia and thalamus. When he started rehabilitation at 5 weeks after onset he was in a vegetative state with a Coma Recovery Scale-Revised score of 6.

DIAGNOSES

The patient was diagnosed spontaneous intracerebral hemorrhage in the right basal ganglia and thalamus.

INTERVENTIONS

He underwent comprehensive rehabilitation including neurotropic durgs, transcranial direct current stimulation, and repetitive transcranial magnetic stimulation of the left prefrontal lobe (Brodmann area 10).

OUTCOMES

After 5 weeks of rehabilitation, the patient had recovered to a nearly normal conscious state with a Coma Recovery Scale-Revised score of 22. On 10-week DTT, thickening of the lower dorsal ARAS was observed on both sides compared with 5-week DTT. Decreased neural connectivity to the left PFC was observed on 5-week DTT whereas decreased neural connectivity to the left PFC was increased on 10-week DTT, especially the mPFC.

LESSONS

Increased thalamocortical connectivity to the mPFC was demonstrated in a stroke patient who showed concomitant recovery from a vegetative state to a nearly normal conscious state. The results suggest that the increased neural connectivity to the mPMC contributed to recovery of consciousness in this patient.

Diffusion Tensor Imaging Studies on Spontaneous Subarachnoid Hemorrhage-Related Brain Injury: A Mini-Review

Accurate diagnosis of the presence and severity of neural injury in patients with subarachnoid hemorrhage (SAH) is important in neurorehabilitation because it is essential for establishing appropriate therapeutic strategies and developing a prognosis. Diffusion tensor imaging has a unique advantage in the identification of microstructural white matter abnormalities which are not usually detectable on conventional brain magnetic resonance imaging. In this mini-review article, 12 diffusion tensor imaging studies on SAH-related brain injury were reviewed. These studies have demonstrated SAH-related brain injuries in various neural tracts or structures including the cingulum, fornix, hippocampus, dorsolateral prefrontal region, corticospinal tract, mamillothalamic tract, corticoreticular pathway, ascending reticular activating system, Papez circuit, optic radiation, and subcortical white matter. We believe that these reviewed studies provide information that would be helpful in science-based neurorehabilitation of patients with SAH. Furthermore, the results of these reviewed studies would also be useful for clarification of the pathophysiological mechanisms associated with SAH-related brain injury. However, considering the large number of neural tracts or neural structures in the brain, more research on SAH-related brain injury in other neural tracts or structures should be encouraged.

Diagnosis of Dizziness Due to a Core Vestibular Projection Injury in a Patient with Intracerebral Hemorrhage

Herein, we present a patient diagnosed with dizziness due to a core vestibular projection injury following intracerebral hemorrhage (ICH). A 51-year-old female patient underwent conservative management for a spontaneous ICH in the left hemisphere (mainly affecting the basal ganglia and insular cortex). When she visited the rehabilitation department of the university hospital at two years after the ICH onset, she advised of the presence of moderate dizziness (mainly, light-headedness) that started after ICH onset. She mentioned that her dizziness had decreased slightly over time. No abnormality was observed in the vestibular system of either ear on physical examination by an otorhinolaryngologist. However, diffusion tensor tractography results showed that the core vestibular projection in the left hemisphere was discontinued at the basal ganglia level compared with the patient’s right core vestibular projection and that of a normal subject. Therefore, it appears that the dizziness in this patient can be ascribed to a left core vestibular projection injury.

Tractography-guided surgery of brain tumours: what is the best method to outline the corticospinal tract?

BACKGROUND

Diffusion tensor imaging (DTI) is the imaging technique used in vivo to visualise white matter pathways. The cortico-spinal tract (CST) belongs to one of the most often delineated tracts preoperatively, although the optimal DTI method has not been established yet. Considering that various regions of interests (ROIs) could be selected, the reproducibility of CST tracking among different centres is low. We aimed to select the most reliable tractography method for outlining the CST for neurosurgeons.

MATERIALS AND METHODS

Our prospective study consisted of 32 patients (11 males, 21 females) with a brain tumour of various locations. DTI and T1-weighed image series were acquired prior to the surgery. To draw the CST, the posterior limb of the internal capsule (PLIC) and the cerebral peduncle (CP) were defined as two main ROIs. Together with these main ROIs, another four cortical endpoints were selected: the frontal lobe (FL), the supplementary motor area (SMA), the precentral gyrus (PCG) and the postcentral gyrus (POCG). Based on these ROIs, we composed ten virtual CSTs in DSI Studio. The fractional anisotropy, the mean diffusivity, the tracts' volume, the length and the number were compared between all the CSTs. The degree of the CST infiltration, tumour size, the patients' sex and age were examined.

RESULTS

Significant differences in the number of tracts and their volume were observed when the PLIC or the CP stood as a single ROI comparing with the two- ROI method (all p < 0.05). The mean CST volume was 40054U (SD ± 12874) and the number of fibres was 259.3 (SD ± 87.3) when the PLIC was a single ROI. When the CP was a single ROI, almost a half of fibres (147.6; SD ± 64.0) and half of the CST volume (26664U; SD ± 10059U) was obtained (all p < 0.05). There were no differences between the various CSTs in terms of fractional anisotropy, mean diffusivity, the apparent diffusion coefficient, radial diffusivity and the tract length (p > 0.05). The CST was infiltrated by a growing tumour or oedema in 17 of 32 patients; in these cases, the mean and apparent diffusion of the infiltrated CST was significantly higher than in uncompromised CSTs (p = 0.04). CST infiltration did not alter the other analysed parameters (all p > 0.05).

CONCLUSIONS

A universal method of DTI of the CST was not developed. However, we found that the CP or the PLIC (with or without FL as the second ROI) should be used to outline the CST.

Diagnosis of Complex Regional Pain Syndrome I Following Traumatic Axonal Injury of the Corticospinal Tract in a Patient with Mild Traumatic Brain Injury

A 54-year-old male suffered from direct head trauma resulting from a fall while working. At approximately two months after the accident, he began to feel pain (burning sensation) and swelling of the dorsum of the right hand and wrist. He showed the following clinical features among the clinical signs and symptoms of revised diagnostic criteria for complex regional pain syndrome (CRPS): spontaneous pain, mechanical hyperalgesia, vasodilation, skin temperature asymmetries, skin color changes, swelling, motor weakness. No specific lesion was observed on brain MRI taken at ten weeks after onset. Plain X-ray, electromyography, and nerve conduction studies for the right upper extremity detected no abnormality. A three-phase bone scan showed hot uptake in the right wrist in the delayed image. On two-month diffusion tensor tractography, partial tearing of the corticospinal tract (CST) was observed at the subcortical white matter in both hemispheres (much more severe in the left CST). In addition, the fiber number of the right CST was significantly decreased than that of seven normal control subjects. CRPS I of the right hand in this patient appeared to be related to traumatic axonal injury of the left CST following mild traumatic brain injury.

Relationship between ataxia and inferior cerebellar peduncle injury in patients with cerebral infarct

INTRODUCTION

The inferior cerebellar peduncle (ICP) is a major neural tract in the cerebellum and is involved in coordination of movement and proprioceptive; therefore, ICP injury can be accompanied by poor coordination of movement, including ataxia. In this study, using diffusion tensor tractography (DTT), we investigated the relationship between ataxia and ICP injury in patients with cerebral infarct.

METHODS

We recruited 14 stroke patients with ataxia after the onset of stroke and 12 normal subjects. The Score of Assessment and Rating of Ataxia (SARA) was used to evaluate ataxia. The values of fractional anisotropy (FA), apparent diffusion coefficient, and fiber number (FN) of the ICP were measured for the diffusion tensor imaging parameters.

RESULTS

Significant differences were observed in the FA and FN values of the ICP in the affected hemisphere between the patient and control groups (P < .05). In addition, the FN value of the ICP in the affected hemisphere showed a negative correlation with SARA (r = -0.538, P < .05). However, parameters of the ICP in the unaffected hemisphere or the FN value in the unaffected hemisphere showed no correlation with SARA (P > .05).

CONCLUSION

We found that the ataxia severity was closely related to the severity of ICP injury in patients with cerebral infarct. Our results suggest that evaluation of the ICP using DTT would be useful for patients with ataxia after cerebral infarct.

Diagnosis of the Trigeminal Nerve Injury in a Patient with Pontine Hemorrhage

Herein, we present a patient who was diagnosed with trigeminal nerve injury following a pontine hemorrhage. A 38-year-old male was diagnosed with a left pontine hemorrhage and underwent conservative management at the neurosurgery department of a university hospital. After hemorrhage onset, he felt facial pain on the right side. After seven years, he visited the rehabilitation department of another hospital for evaluation of his right facial pain. He complained of somatosensory impairment and facial pain (tingling and cold sensation) on the right side as well as difficulty chewing and gait disturbance. On neurological examination, decreased touch sensation (approximately 30%) was observed on the right side of the face, in the oral cavity, and on the tongue (anterior two-thirds) as well as weakness of the right-sided masseter muscles. He also exhibitedallodynia without dysesthesia on the right side of the face. Diffusion tensor tractography showed the right trigeminal nerve to be discontinued at the anterior margin of the pons (arrow) compared to the state of the left trigeminal nerve.

Diagnosis of Tinnitus Due to Auditory Radiation Injury Following Whiplash Injury: A Case Study

We report on a patient with tinnitus who showed injury of auditory radiation following whiplash injury, demonstrated by diffusion tensor tractography (DTT). A 48-year-old male patient suffered from a car crash resulting in flexion-hyperextension injury of his head after being hit from behind by a moving car while waiting at a signal while driving a car. Three days after the car crash, he began to feel tinnitus in both ears and his tinnitus became aggravated with the passage of time. No specific lesion was observed on a conventional brain MRI performed two weeks after the car crash. Although he visited several hospitals, the precise cause of his tinnitus was not detected. Two years after the car crash, he underwent evaluation for his tinnitus at the ear, nose and throat department of a university hospital. The pure tone audiometry was evaluated in a sound-proof room to screen his hearing status for the frequencies of 250-8000 Hz and no specific abnormality was detected. Although he was also tested for speech audiometry, there was also no specific abnormality. In order to assess his tinnitus, a tinnitogram was conducted to evaluate the frequency content and the loudness. His tinnitus was characterized at an intensity of 40 dB and a frequency of 4000 Hz. However, no abnormality was observed in either ear on physical examination. On DTT, the auditory radiation showed severe narrowing and tearing in both hemispheres. To summarize, neural injury of the auditory radiation was demonstrated in a patient with tinnitus following whiplash injury, using DTT.

Differences in Corticoreticulospinal Tract Injuries According to Whiplash in Mild Traumatic Brain Injury Patients

Background: This study investigated differences in postural control ability (PCA) and corticoreticulospinal tract (CRT) injury severity according to whiplash in patients with mild traumatic brain injury (mTBI).

Methods: Thirty-one patients with mTBI and 21 healthy control subjects were recruited for this study. The balance error scoring system (BESS) was used for PCA assessment. Based on their whiplash history, the patients were classified into two groups: group A—mTBI with whiplash injury; group B—mTBI without whiplash injury. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), and tract volume (TV) values were estimated for the reconstructed CRTs in all subjects.

Results: Significant differences were observed among the total BESS scores of patient groups A and B and the control group (p < 0.05). The patient group A BESS score was significantly higher than that of patient group B, and that of the patient group B was significantly higher than that of the control group. No significant differences were detected among the FA and ADC values of the CRTs of the two patient groups and the control group (p > 0.05). However, the TV values of the CRT did reveal significant differences; the TV of patient group A was significantly lower than those of patient group B and the control group, and that of patient group B was significantly lower than that of the control group (p < 0.05).

Conclusions: We observed greater CRT injury severity and PCA impairment in mTBI patients with whiplash than in mTBI patients without whiplash. The results indicate that whiplash might lead to a greater level of severity in axonal injuries in mTBI patients.

Characteristics of the Uncinate Fasciculus and Cingulum in Patients with Mild Cognitive Impairment: Diffusion Tensor Tractography Study

Many studies have examined the relationship between cognition, and the cingulum and uncinate fasciculus (UF). In this study, diffusion tensor tractography (DTT) was used to investigate the correlation between fractional-anisotropy (FA) values and the number of fibers in the cingulum and UF in patients with and without cognitive impairment. The correlation between cognitive function, and the cingulum and UF was also investigated. Thirty patients (14 males, age = 70.68 ± 7.99 years) were divided into a control group (n = 14) and mild-cognitive-impairment (MCI) group (n = 16). The Seoul Neuropsychological Screening Battery (SNSB) and DTT were performed to assess cognition and bilateral tracts of the cingulum and UF. The relationship between SNSB values and the cingulum and UF was analyzed. The number of fibers in the right cingulum and right UF were significantly different between the two groups. The MCI group showed thinner tracts in both the cingulum and UF compared to the control group. A significant relationship was found between the number of fibers in the right UF and delayed memory recall. In conclusion, memory loss in MCI was associated with a decreased number of fibers in the right UF, while language and visuospatial function were related to the number of fibers in the right cingulum.

Corticoreticular Tract in the Human Brain: A Mini Review

Previous studies have suggested that the corticoreticular tract (CRT) has an important role in motor function almost next to the corticospinal tract (CST) in the human brain. Herein, the CRT is reviewed with regard to its anatomy, function, and recovery mechanisms after injury, with particular focus on previous diffusion tensor tractography-based studies. The CRT originates from several cortical areas but mainly from the premotor cortex. It descends through the subcortical white matter anteromedially to the CST with a 6- to 12-mm separation in the anteroposterior direction, then passing through the mesencephalic tegmentum and the pontine and pontomedullary reticular formations. Regarding its motor functions, the CRT appears to be mainly involved in the motor function of proximal joint muscles accounting for ~30–40% of the motor function of these joint muscles. In addition, the CRT is involved in gait function and postural stability. However, further studies that clearly rule out the effects of other motor function-related neural tracts are necessary to clarify the precise portion of the total motor function for which the CRT is responsible. With regard to recovery mechanisms for an injured CRT, three recovery mechanisms were suggested in five previous studies: recovery through the original pathway, recovery through perilesional reorganization, and recovery through the transcallosal pathway. However, each of those studies was single-case reports; therefore, further original studies including a larger number of patients are warranted.

Central Pain Due to Injury of the Spinothalamic Tract Misdiagnosed as Complex Regional Pain Syndrome: A Case Report

Objectives: We report on a patient with whiplash injury who had central pain, due to injury of the spinothalamic tract (STT), but who was misdiagnosed as complex regional pain syndrome (CRPS). Case description: While a minivan in which a 43-year-old female was seated in the passenger seat was stopped for a signal, a truck collided with the minivan from behind, and the minivan then repeatedly collided with trucks in front and behind the minivan. Her head repeatedly struck the minivan seat resulting in whiplash injuries. After onset, she felt pain in both legs with mild motor weakness in all four extremities and memory impairment. Eight years after onset, she was diagnosed at a university hospital as CRPS type 1 with the clinical features of hyperalgesia and mild edema and motor weakness of both legs. She visited another university hospital nine years after onset and complained of pain in the right arm and both legs, constant tingling and burning pain along with allodynia and hyperalgesia. She also showed mild weakness in the four extremities, mild edema of both legs, and memory impairment. On diffusion tensor tractography (DTT), the left spinothalamic tract (STT) showed marked narrowing, and the right STT revealed mild narrowing and partial tearing. In addition, partial tears were observed in both corticospinal tracts and the right corticoreticulospinal tract. Discontinuations were observed in the left corticoreticulospinal tract and the left fornical crus. Conclusion: Injury of the STT was demonstrated on DTT in a patient with central pain following whiplash injury. Previously, the patient was misdiagnosed as CRPS.

Differences in corpus callosum injury between cerebral concussion and diffuse axonal injury

BACKGROUND

We investigated differences in corpus callosum (CC) injuries between patients with concussion and those with diffuse axonal injury (DAI) by using diffusion tensor tractography (DTT).

METHODS

Twenty-nine patients with concussion, 21 patients with DAI, and 25 control subjects were recruited. We reconstructed the whole CC and 5 regions of the CC after applying Hofer classification (I, II, III, IV, and V). The whole CC and each region of the CC were analyzed to measure DTT parameters (fractional anisotropy [FA], apparent diffusion coefficient [ADC], and fiber number [FN]).

RESULTS

In the whole CC, significant differences were observed in all DTT parameters between the concussion and control groups and the DAI and control groups (P < .05). Among the 5 regions of the CC, significant differences were observed in FA and ADC between the concussion and control groups and the DAI and control groups (P < .05). Significant differences in FN were observed in CC regions I and II (connected with the prefrontal lobe and secondary motor area) between the concussion and control groups, in CC regions I, II, III, and IV (connected with the frontoparietal lobes) between the DAI and control groups, and in CC regions III, IV (connected with the motor-sensory cortex) between the concussion and DAI groups (P < .05).

CONCLUSION

It was observed that both concussion and DAI patients showed diffuse neural injuries in the whole CC and all 5 regions of the CC. Neural FN results revealed that concussion patients appeared to be specifically injured in the anterior part of the CC connected with the frontal lobe, whereas DAI patients were injured in more diffuse regions connected with whole frontoparietal lobes.

Severe Apathy Due to Injury of Prefronto-caudate Tract

The caudate nucleus, which is vulnerable to hypoxic–ischemic brain injury (HI-BI), is important to cognitive function because it is connected to the prefrontal cortex. Using diffusion tensor tractography (DTT), no study on injury of the prefronto-caudate tract in a patient with HI-BI has been reported so far. Here, we report a patient with severe apathy who showed injury of the prefronto-caudate tract following HI-BI, which was demonstrated by DTT. A 38-year-old female patient suffered HI-BI induced by carbon monoxide poisoning following attempted suicide for a period of approximately four hours. From the onset, the patient showed severe apathy (7 months after onset-the Apathy Scale score was 24 [full score: 42]). Brain MR images taken at seven months after onset showed no abnormality. On 7-month DTT, the neural connectivity of the caudate nucleus to the medial prefrontal cortex (Brodmann area: 10 and 12) and orbitofrontal cortex (Brodmann area: 11 and 13) was decreased in both hemispheres. Using DTT, injury of the prefronto-caudate tract was demonstrated in a patient who showed severe apathy following HI-BI. We believe that injury of the prefronto-caudate tract might be a pathogenetic mechanism of apathy in patients with HI-BI.

Diffusion Tensor Tractography Studies of Central Post-stroke Pain Due to the Spinothalamic Tract Injury: A Mini-Review

Elucidation of the pathophysiological mechanism of central post-stroke pain (CPSP) is essential to the development of effective therapeutic modalities for CPSP. However, the pathophysiological mechanism of CPSP has not yet been clearly elucidated. The recent development of diffusion tensor tractography (DTT), derived from diffusion tensor imaging (DTI), has allowed visualization and estimation of the spinothalamic tract (STT), which has been considered the most plausible neural tract responsible for the pathogenesis of CPSP. In this mini-review, six DTT studies in which CPSP due to STT injury in stroke patients was demonstrated are reviewed. The information provided in the reviewed studies suggests that DTT is useful in the elucidation of the pathophysiological mechanism associated with CPSP. We believe that the reviewed studies will facilitate neurorehabilitation of stroke patients with CPSP. However, DTT studies of CPSP are still in the beginning stage because the total number (six studies) of the reviewed studies is very low and half were case reports. Therefore, further studies involving large numbers of subjects are warranted.

Deterioration of Brain Neural Tracts in Elderly Women with Sarcopenia

OBJECTIVES

Sarcopenia is known to be associated with increased stiffness in brain arteries, which causes deterioration in brain structure and function. In this study, the authors evaluated the deterioration of neural tracts using diffusion tensor tractography (DTT) in elderly women with sarcopenia and investigated whether deterioration of neural tracts is consistent with clinical findings.

METHODS

Twenty elderly women with sarcopenia were recruited. Muscle mass was measured by dual energy x-ray absorptiometry. Hand-grip power and gait speed were also assessed. Memory function was evaluated using the Seoul Neuropsychological Screening Battery. Additionally, using DTT-Studio software, the authors evaluated eight neural tracts: the corticospinal tract (CST), corticoreticular pathway, fornix, cingulum, superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and optic radiation. The authors measured the DTT parameters (fractional anisotropy [FA] and fiber volume [FV]) for each neural tract.

RESULTS

The FA and FV values were decreased in all the evaluated neural tracts, compared with those of the 20 normal comparison subjects. The FVs of the CST were significantly correlated with the hand-grip power of elderly women with sarcopenia. The FVs of the fornix and cingulum in elderly women with sarcopenia were significantly correlated with their memory function.

CONCLUSION

The authors found that the neural tracts in elderly women with sarcopenia were extensively deteriorated, and their hand-grip power and memory function were associated with related neural tracts. The DTT seems to be a useful tool for evaluating structural changes in the brains of people with sarcopenia.

Anatomical and Surgical Evaluation of the Common Marmoset as an Animal Model in Hearing Research

Recent studies have indicated that direct administration of viral vectors or small compounds to the inner ear may aid in the treatment of Sensorineural hearing loss (SNHL). However, due to species differences between humans and rodents, translating experimental results into clinical applications remains challenging. The common marmoset (Callithrix jacchus), a New World monkey, is considered a pre-clinical animal model. In the present study, we describe morphometric data acquired from the temporal bone of the common marmoset in order to define the routes of topical drug administration to the inner ear. Dissection and diffusion tensor tractography (DTT) were performed on the fixed cadaverous heads of 13 common marmosets. To investigate potential routes for drug administration to the inner ear, we explored the anatomy of the round window, oval window (OW), semicircular canal, and endolymphatic sac (ES). Among these, the approach via the round window with posterior tympanotomy appeared feasible for delivering drugs to the inner ear without manipulating the tympanic membrane, minimizing the chances of conductive hearing loss. The courses of four critical nerves [including the facial nerve (FN)] were visualized using three-dimensional (3D) DTT, which may help to avoid nerve damage during surgery. Finally, to investigate the feasibility of actual drug administration, we measured the volume of the round window niche (RWN), which was approximately 0.9 μL. The present findings may help to establish experimental standards for evaluating new therapies in this primate model.

Predictive role of subcomponents of the left arcuate fasciculus in prognosis of aphasia after stroke: A retrospective observational study

The relationship between the left arcuate fasciculus (AF) and stroke-related aphasia is unclear. In this retrospective study, we aimed to investigate the role of subcomponents of the left AF in predicting prognosis of aphasia after stroke. Twenty stroke patients with aphasia were recruited and received language assessment as well as diffusion tensor tractography scanning at admission. According to injury of the left AF, the participants were classified into four groups: group A (4 cases), the AF preserved intactly; group B (6 cases), the anterior segment injured; group C (4 cases), the posterior segment injured; and group D (6 cases), completely injured. After a consecutive speech therapy, language assessment was performed again. Changes of language functions among the groups were compared and the relation between these changes with segments injury of the AF was analyzed. After therapy, relatively high increase score percentage changes in terms of all the subcategories of language assessment were observed both in group A and C; by contrast, only naming in group B, and spontaneous speech in group D. Although no statistical difference was demonstrated among the four groups. In addition, there was no significant correlation between improvement of language function with segments injury of the AF. The predictive role of subcomponents of the left AF in prognosis of aphasia is obscure in our study. Nevertheless, it indicates the importance of integrity of the left AF for recovery of aphasia, namely that preservation of the left AF on diffusion tensor tractography could mean recovery potential of aphasia after stroke.

Microstructural integrity of corticospinal and medial lemniscus tracts: insights from diffusion tensor tractography of right-hand amputees

Reductions in sensory and motor activity following unilateral upper limb amputation during adulthood are associated with widespread, activity-dependent reorganization of the gray matter and white matter through the central nervous system. Likewise, in cases of congenital limb absence there is evidence that limited afferent or efferent activity affects the structural integrity of white matter pathways serving the affected side. Evidence that the structural integrity of mature sensory and motor tracts controlling the lost upper limb exhibits similar activity dependence is, however, sparse and inconsistent. Here we used diffusion tensor tractography to test whether amputation of the dominant right hand during adulthood (n = 16) alters the microstructural integrity of the major sensory (medial lemniscus, ML) and motor (corticospinal tract, CST) pathways controlling missing hand function. Consistent with prior findings, healthy control subjects (n = 27) exhibited higher fractional anisotropy (FA), an index of white matter microstructural integrity, within dominant left CST and nondominant right ML. Critically, in contrast to what might be expected if the microstructural organization of these tracts is activity dependent, these asymmetries persisted in amputees. Moreover, we failed to detect any differences in dominant left ML or CST between healthy control subjects and amputees. Our results are consistent with these white matter tracts being robust to changes in activity once mature or that continued use of the residual limb (in a compensatory fashion or with prosthesis) provides stimulation sufficient to maintain tract integrity. NEW & NOTEWORTHY We report that unilateral hand amputation in adults has no significant effects on the structure of major sensory or motor pathways contralateral to the amputation. Our results are consistent with the organization of these white matter tracts being robust to changes in activity once mature or that continued use of the residual limb (with or without a prosthesis) provides stimulation sufficient to maintain tract integrity.

Diffusion tensor tractography to visualize axonal outgrowth and regeneration in a 4-cm reverse autograft sciatic nerve rabbit injury model

BACKGROUND

Diffusion tensor tractography (DTT) has recently been shown to accurately detect nerve injury and regeneration. This study assesses whether 7-tesla (7T) DTT imaging is a viable modality to observe axonal outgrowth in a 4 cm rabbit sciatic nerve injury model fixed by a reverse autograft (RA) surgical technique.

METHODS

Transection injury of unilateral sciatic nerve (4 cm long) was performed in 25 rabbits and repaired using a RA surgical technique. Analysis of the nerve autograft was performed at 3, 6, and 11 weeks postoperatively and compared to normal contralateral sciatic nerve, used as control group. High-resolution DTT from ex vivo sciatic nerves were obtained using 3D diffusion-weighted spin-echo acquisitions at 7-T. Total axons and motor and sensory axons were counted at defined lengths along the graft.

RESULTS

At 11 weeks, histologically, the total axon count of the RA group was equivalent to the contralateral uninjured nerve control group. Similarly, by qualitative DTT visualization, the 11-week RA group showed increased fiber tracts compared to the 3 and 6 weeks counterparts. Upon immunohistochemical evaluation, 11-week motor axon counts did not significantly differ between RA and control; but significantly decreased sensory axon counts remained. Nerves explanted at 3 weeks and 6 weeks showed decreased motor and sensory axon counts.

DISCUSSION

7-T DTT is an effective imaging modality that may be used qualitatively to visualize axonal outgrowth and regeneration. This has implications for the development of technology that non-invasively monitors peripheral nerve regeneration in a variety of clinical settings.

Recovery of an injured corticospinal tract via an unusual pathway in a stroke patient: Case report

RATIONALE

A few mechanisms of recovery from an injured corticospinal tract (CST) in stroke patients have been reported: recovery of an injured CST through (1) normal CST pathway, (2) peri-lesional reorganization, and (3) shifting of the cortical origin area of an injured CST from the other areas to the primary motor cortex. However, it has not been clearly elucidated so far.

PATIENT CONCERNS

A 57-year-old male patient presented with complete weakness of the right extremities due to an intracerebral hemorrhage (ICH) in the left basal ganglia. At three weeks after onset, the patient showed severe weakness of his right upper and lower extremities (Motricity Index [MI]: 28/100, finger extensor: 0/5). At 6 months after onset, his weakness showed some recovery, however, right finger extensor did not show any recovery (MI: 51/100, finger extensor: 0/5). At 9 months after onset, weakness showed significant recovery, particularly right finger extensor (MI: 64/100, right finger extensor: 3/5) and similar motor function persisted until 11 months after onset (MI: 67/100, right finger extensor: 3/5).

DIAGNOSES

The patient was diagnosed as the right hemiplegia due to ICH in the left corona radiata and basal ganglia.

INTERVENTIONS

Clinical assessment, transcranial magnetic stimulation (TMS), and diffusion tensor tractography (DTT) were performed at 1, 6, 9, and 11 months after onset.

OUTCOMES

Discontinuation of the left CST at the midbrain level was observed on 1-month DTT and the corona radiata on 6-month DTT. However, on 9-month DTT, we observed a CST branch originating from the left posterior parietal cortex and then connecting to the main truck to the CST at the thalamic level and thickened on 11-month DTT. On 1-month TMS, no MEP was evoked from the left hemisphere; on 6-month TMS study, MEPs were obtained at a right hand muscle (latency: 22.8 ms, amplitude: 130 μV) and its amplitude was increased as 300 μV with similar latencies on 9- and 11-month TMS studies.

LESSONS

Recovery of an injured CST via an unusual pathway was demonstrated in a hemiparetic patient with ICH, using DTT and TMS. We believe that our results suggest that precise evaluation for an injured CST using TMS and DTT might be necessary, particularly in young patients, even after 6 months from onset even though the stroke patients show clinical characteristics of severe injury of the affected CST.

Traumatic axonal injury of the cingulum in patients with mild traumatic brain injury: a diffusion tensor tractography study

The cingulum, connecting the orbitofrontal cortex to the medial temporal lobe, involves in diverse cognition functions including attention, memory, and motivation. To investigate the relationship between the cingulum injury and cognitive impairment in patients with chronic mild traumatic brain injury, we evaluated the integrity between the anterior cingulum and the basal forebrain using diffusion tensor tractography in 73 patients with chronic mild traumatic brain injury (39 males, 34 females, age 43.29 ± 11.42 years) and 40 healthy controls (22 males, 18 females, age 40.11 ± 16.81 years). The patients were divided into three subgroups based on the integrity between the anterior cingulum and the basal forebrain on diffusion tensor tractography: subgroup A (n = 19 patients) - both sides of the anterior cingulum were intact; subgroup B (n = 36 patients) - either side of the anterior cingulum was intact; and subgroup C (18 patients) - both sides of the anterior cingulum were discontinued. There were significant differences in total Memory Assessment Scale score between subgroups A and B and between subgroups A and C. There were no significant differences in diffusion tensor tractography parameters (fractional anisotropy, apparent diffusion coefficient, and fiber volume) between patients and controls. These findings suggest that the integrity between the anterior cingulum and the basal forebrain, but not diffusion tensor tractography parameter, can be used to predict the cognitive function of patients with chronic mild traumatic brain injury. This study was approved by Yeungnam University Hospital Institutional Review Board (approval No. YUMC-2014-01-425-010) on August 16, 2017.

Diffusion Tensor Tractography Studies on Injured Anterior Cingulum Recovery Mechanisms: A Mini-Review

The cingulum, a major structure in the limbic system, contains the medial cholinergic pathway, which originates from the basalis nucleus of Meynert (Ch 4) in the basal forebrain. The cingulum is involved in various cognitive functions, including memory, attention, learning, motivation, emotion, and pain perception. In this mini-review, 10 studies reporting on recovery mechanisms of injured cinguli in patients with brain injury were reviewed. The recovery mechanisms of the injured anterior cinguli reported in those 10 studies are classified as follows: Mechanism 1, recovery via the normal pathway of the cingulum between the injured cingulum and Ch 4; mechanism 2, recovery through the neural tract between the injured cingulum and the brainstem cholinergic nuclei; mechanism 3, recovery via the lateral cholinergic pathway between the injured cingulum and the white matter of the temporo-occipital lobes; mechanism 4, recovery through the neural tract between the contralesional basal forebrain and the ipsilesional basal forebrain via the genu of the corpus callosum; and mechanism 5, recovery through the neural tract between the injured cingulum and Ch 4 via an aberrant pathway. Elucidation of the recovery mechanisms of injured anterior cinguli might be useful for neurorehabilitation of patients with anterior cingulum injuries. Diffusion tensor tractography appears to be useful in the detection of recovery mechanisms of injured anterior cinguli in patients with brain injury. However, studies on cingulum injury recovery mechanisms are still in the early stages because most of the above studies are case reports confined to a few brain pathologies. Therefore, further studies involving large numbers of subjects with various brain pathologies should be encouraged. In addition, studies on the influencing factors and clinical outcomes associated with each recovery mechanism are warranted.

Laterality of cerebellar afferent and efferent pathways in a healthy right-handed population: A diffusion tensor imaging study

The cerebellum communicates with the cerebral cortex through the cortico-ponto-cerebellar tract (CPCT, cerebellar afferent) and the dentato-rubro-thalamo-cortical tract (DRTCT, cerebellar efferent). This study explored the laterality of CPCT and DRTCT in a right-handed population. Forty healthy right-handed subjects (18 males and 22 females with age range of 26-79 years old) who underwent diffusion tensor imaging (DTI) were retrospectively enrolled. Bilateral CPCT, DRTCT, and the corticospinal tract (CST) were reconstructed using probabilistic diffusion tensor tractography (DTT). Tract volume (TV) and fractional anisotropy (FA) were compared between dominant and non-dominant tracts. Subjects were divided into age groups (20-40, 41-60, and 61-80 years), and the DTI-derived parameters of the groups were compared to determine age-related differences. TV and FA of non-dominant CPCT were higher than those of dominant CPCT, and the dominant CST was higher than the non-dominant CST. The TV and FA of DRTCT showed no side-to-side difference. The 61-80 years age group had the highest TV of the dominant and non-dominant DRTCT among the three groups and the highest FA of the non-dominant CPCT and DRTCT. The results revealed the structural characteristics of CPCT and DRTCT using probabilistic DTT. Normal asymmetric patterns and age-related changes in cerebellar white matter tracts may be important to researchers investigating cerebro-cerebellar structural connectivity.

Effect of Neuromuscular Electrical Stimulation Training on the Finger Extensor Muscles for the Contralateral Corticospinal Tract in Normal Subjects: A Diffusion Tensor Tractography Study

Objectives: Neuromuscular electrical stimulation (NMES) is a popular rehabilitative modality to improve motor function of the extremities and trunk. In this study, we investigated changes of hand function and the contralateral corticospinal tract (CST) with treatment by NMES on the finger extensor muscles for 2 weeks, using serial diffusion tensor tractography (DTT).

Methods: Thirteen right handed normal subjects were recruited. Treatment was applied to the left hand (the NMES side), and the right hand was the control side. NMES was applied for 30 min/day, 7 days per week, for 2 weeks. Hand motor function was evaluated twice at pre-NMES and post-NMES training using grip strength (GS), Purdue pegboard test (PPT) and tip pinch. The fractional anisotropy (FA), mean diffusivity (MD) and tract volume (TV) of the CST in both hemispheres were measured using DTT.

Results: On the control side, the clinical scores did not differ significantly between pre- and post-NMES training (p > 0.05). However, on the NMES side, PPT and tip pinch improved significantly (p < 0.05), although GS did not. TV of the right CST increased significantly at post-NMES training (p < 0.05) whereas FA and MD did not differ significantly (p > 0.05). By contrast, FA, MD and TV on the left CST did not change significantly (p > 0.05).

Conclusion: We demonstrated facilitation of the contralateral CST with improvement of fine motor activity by 2 weeks of NMES training of peripheral muscles in normal subjects. We think our results can be applied to the normal subjects and patients with brain injury to improve the fine motor function of the hand and facilitate the normal CST or healing of the injured CST.

Recovery process of bilaterally injured corticoreticulospinal tracts in a patient with subarachnoid hemorrhage: Case report

RATIONALE

A few studies using diffusion tensor tractography (DTT) have demonstrated recovery of injured corticoreticulospinal tract (CRT) in patients with intracerebral hemorrhage and infarct. However, no study reported on a patient who showed peri-infarct reorganization of an injured CRT following a middle cerebral artery territory infarct.

PATIENT CONCERNS

A 56-year-old right-handed male patient was diagnosed as spontaneous subarachnoid hemorrhage (SAH) and intraventricular hemorrhage (IVH) and underwent clipping for a ruptured anterior communicating artery aneurysm and right frontal extraventricular drainage for IVH at the department of neurosurgery of a university hospital. After onset, he presented with complete weakness of both legs.

DIAGNOSES

The patient was diagnosed as spontaneous SAH and IVH.

INTERVENTIONS

Clinical assessment and DTT were performed at 1, 3, 6, and 20 months after onset.

OUTCOMES

The weakness of both legs showed slow recovery for 10 months until 11 months after onset (medical research council: 6 months; 3/3 and 11 months; 4/4). As a result, he was able to walk independently on an even floor at 6 months and on stairs at 11 months after onset. The discontinued both CRTs on 1-month DTT were restored to the cerebral cortex on 3-month DTT, and then thickened consecutively on 6-month and 20-month DTTs.

LESSONS

The recovery process of injured CRTs concurrent with recovery of leg weakness was demonstrated in a patient with SAH using DTT. This study has important implications in terms of regaining gait function by the recovery of bilaterally injured CRTs which was facilitated by the long-term rehabilitation.

Delayed-onset central poststroke pain due to degeneration of the spinothalamic tract following thalamic hemorrhage: A case report

RATIONALE

Recent studies have used diffusion tensor tractography (DTT) to demonstrate that central poststroke pain (CPSP) was related to spinothalamic tract (STT) injury in patients with stroke. However, few studies have been reported about delayed-onset CPSP due to degeneration of the STT following a stroke.

PATIENT'S CONCERNS

A 57-year-old female patient presented with right hemiparesis after stroke. Two weeks after onset, she did not report any pain. At approximately 6 months after onset, she reported pain in the right arm and leg, and the pain slowly intensified with the passage of time. At 14 months after onset, the characteristics and severity of her pain were assessed to be continuous pain without allodynia or hyperalgesia; tingling and cold-sensational pain in her right whole arm and leg (visual analog scale score: 5).

DIAGNOSES

The patient was diagnosed as the right hemiparesis due to spontaneous thalamic hemorrhage.

INTERVENTIONS

Clinical assessment and diffusion tensor imaging (DTI) were performed 2 weeks and 14 months after onset.

OUTCOMES

She suffered continuous pain in her right whole arm and leg (visual analog scale score: 5). On DTT of the 2-week postonset DTI scans, the configuration of the STT was well-preserved in both hemispheres. However, in contrast to those 2-week postonset results, the 14-month postonset DTT results showed partial tearing and thinning in the left STT. Regardless, both the 2-week and 14-month postonset DTT showed that the left STT passed through the vicinity of the thalamic lesion.

LESSONS

Diagnostic importance of performing a DTT-based evaluation of the STT in patients exhibiting delayed-onset CPSP following intracerebral hemorrhage.

The different association of allocentric and egocentric neglect with dorsal and ventral pathways: A case report

RATIONALE

Egocentric neglect is characterized by responses missing on the contralateral side with respect to the viewer, while allocentric neglect is characterized in responses missing on the contralateral side with respect to the object . However, little has been reported about the neural tracts associated with egocentric and allocentric neglect. We investigated which neural tracts were involved in two types of neglect (egocentric and allocentric) in a stroke patient who showed allocentric neglect by using the Apple Cancellation test, a specialized test to distinguish between egocentric and allocentric neglect.

PATIENT CONCERNS

He showed good cognitive function but presented with severe neglect on the left side (A 42-year-old, right-handed male patient). He was unable to undergo even the pencil and paper test for evaluation of the severity of neglect.

DIAGNOSES

He was diagnosed as spontaneous intracerebral hemorrhage at the right basal ganglia and underwent conservative management at the neurosurgery department of a university hospital.

INTERVENTIONS

Two weeks after onset, he began rehabilitation at the rehabilitation department of the same university hospital. During a seven month rehabilitation, the patient showed significant improvement of his severe left neglect.

OUTCOMES

We used the Apple Cancellation test to distinguish between egocentric and allocentric neglect; the results failed to reveal egocentric neglect, however, they did reveal severe allocentric neglect. In addition, on diffusion tensor tractography (DTT) at 2 weeks after onset, the right superior longitudinal fasciculus (SLF) showed partial injury and narrowing in the parietal lobe compared to that of the left SLF. In addition, the right inferior fronto-occipital fasciculus (IFOF) was not reconstructed. By contrast, on 7-month post-onset DTT, the right SLF revealed elongation and thickening in the parietal lobe that approached similarity to that for the left SLF. However, the right IFOF was still not reconstructed.

LESSONS

The associations of egocentric neglect with the dorsal pathway (SLF) and the association of allocentric neglect with the ventral pathway (IFOF) in the right hemisphere were demonstrated in a stroke patient. It appears that DTT can be helpful in demonstrating both the affected pathway and the neglect type in patients with neglect.

Mechanism of cognitive impairment in chronic patients with putaminal hemorrhage: A diffusion tensor tractography

It is not clear whether the fornix and cingulum are involved in cognition after putaminal hemorrhage (PH). We investigated structural changes and differences of the neural tracts, and the relationship between the integrity of the neural tracts and cognition not only at the affected but also at the unaffected side.Sixteen patients with left chronic putaminal hemorrhage and 20 healthy volunteers were enrolled. Using diffusion tensor tractography (DTT), we compared fiber number (FN), fractional anisotropy (FA), and apparent diffusion coefficient (ADC) of the neural tracts between patient and control groups. The relationship between the neural tract parameters and neuropsychological results was also analyzed.The left fornix FN was significantly lower than the right fornix FN in the patient group. Except for the cingulum FA, the neural tracts parameters for both the affected and unaffected hemispheres differed significantly between the groups. The fornix FA and ADC at the affected side were significantly correlated with intelligence quotient (IQ), mini-mental status examination (MMSE), and short-term memory. Interestingly, the fornix ADC at the unaffected side was significantly correlated with MMSE. However, none of the cingulum parameters was correlated with neuropsychological results.The fornix integrity is critical for cognitive impairment after putaminal hemorrhage.

Changes in the corpus callosum during the recovery of aphasia: A case report

RATIONALE

The corpus callosum, which is the most important fiber pathway linking the bilateral hemispheres, plays a key role in information access, as well as the functional coordination and reorganization between the bilateral hemispheres. However, whether the corpus callosum will undergo structural changes during the recovery of aphasia is still unclear. In the current study, a Chinese aphasic patient with stroke was reported to develop changes in the corpus callosum after speech therapy.

PATIENT CONCERNS

A 33-year-old right-handed male patient had aphasia only without limb paralysis at 14 months after stroke.

DIAGNOSES

Neuroimaging evaluation confirmed a diagnosis of cerebral infarction in the left frontal lobe, insula and basal ganglia.

INTERVENTIONS

He underwent 5-month speech therapy and received language function evaluation and DTI examination before and after speech therapy.

OUTCOMES

The result ABC showed that the language functions in the patient, including spontaneous speech, auditory comprehension, repetition and naming, were improved after the speech therapy. In addition, results of follow-up DTT suggested that the fiber pathway between the splenium of corpus callosum and the left superior temporal gyrus (Wernicke's area) had been established. At the same time, fiber connections between the genu of corpus callosum and the right inferior frontal gyrus (the mirror region of Broca's area) were increased.

LESSONS

The fibrous structure between the corpus callosum and cortical language areas may be reconstructed during the recovery of aphasia. In addition, and the corpus callosum may play an important role in the occurrence and recovery of aphasia after stroke.

Recovery of an injured medial lemniscus with concurrent recovery of pusher syndrome in a stroke patient: a case report

RATIONALE

A 67-year-old, right-handed male patient underwent craniotomy and drainage for hematoma removal related to an intracerebral hemorrhage (ICH) in the right thalamus and basal ganglia at the neurosurgery department of a university hospital.

PATIENT CONCERNS

He presented with severe motor weakness of left extremities, impairment of proprioception, and severe pusher syndrome at the start of rehabilitation.

DIAGNOSES

He was diagnosed as ICH in the right thalamus and basal ganglia.

INTERVENTIONS

The patient received comprehensive rehabilitative therapy, movement therapy, and somatosensory stimulation.

OUTCOMES

Four months after onset, left leg motor function (Motricity Index [MI] = 51) did not show significant recovery from that at two months after onset (MI = 41); however, in the same period, Nottingham Sensory Assessment and scale for contraversive pushing significantly improved. At four months, the patient was able to stand independently but required manual contact of one person during independent walking on an even floor. At seven months after onset, he was able to walk independently on an even floor.

LESSONS

Recovery of a severely injured medial lemniscus with concurrent recovery of impaired proprioception and pusher syndrome.

Excessive Daytime Sleepiness and Injury of the Ascending Reticular Activating System Following Whiplash Injury

Objectives: This study investigated injuries of the ascending reticular activating system (ARAS) following whiplash injury, in patients with excessive daytime sleepiness (EDS). Methods: Twenty-three patients with whiplash injury and 26 healthy control subjects were recruited for this study. Epworth Sleepiness Scale (ESS) was used for evaluating sleepiness. According to the ESS score, the patients were classified into two groups: subgroup A - ESS score <10, and subgroup B - ESS score ≥10. Three components of the ARAS (lower dorsal, lower ventral, and upper) were evaluated for fractional anisotropy (FA) and tract volume (TV). Results: No significant differences were observed in the FA and TV values of the lower dorsal and upper ARAS between the patient and control groups (p > 0.05). Conversely, the values of FA and TV in the lower ventral ARAS of the patient group were significantly lower than those of the control group (p < 0.05). Comparing the values of subgroups A and B, the TV value of subgroup B was significantly lower than subgroup A (p < 0.05). However, no significant differences were observed in the values of the FA and TV in the lower dorsal and upper ARAS, and the FA value in the lower ventral ARAS (p > 0.05). Conclusions: We found significant injury of the lower ventral ARAS in EDS patients with whiplash injury. These results suggest that diffusion tensor tractography (DTT) could provide useful information for detecting injuries of the ARAS following whiplash injury, in patients with EDS.

Injury of leg somatotopy of corticospinal tract at corona radiata by ventriculoperitoneal shunt: A case report

RATIONALE

A 45-year-old right-handed female patient suffered head trauma after being hit by a truck that ran into a house.

PATIENT CONCERNS

The patient lost consciousness for 1 hour and experienced posttraumatic amnesia for 1 month after the accident.

DIAGNOSES

She underwent conservative management for a subdural hematoma in the left frontotemporal lobes and intracerebral hematoma in the left frontal lobe.

INTERVENTIONS

The patient's Glasgow Coma Scale score was 11. She underwent a VP shunt operation, approached through the right posterior parietal area of the brain, at 4 months after onset. Approximately, 6 months after onset, she was admitted to the rehabilitation department of a university hospital. She presented with moderate weakness of the left leg: Medical Research Council scores: hip flexor; 3, knee extensor; 3+, ankle dorsiflexor; 3-. Brain magnetic resonance imaging revealed a leukomalactic lesion in the right posterior corona radiata along the shunt.

OUTCOMES

On 6-month (2 months after the shunt operation) diffusion tensor tractography, the left CST showed partial injury in the posterior portion compared with the right CST. On 6-month transcranial magnetic stimulation study, the motor-evoked potential obtained at the left tibialis anterior muscle revealed lower amplitude than that on the right side.

LESSONS

Injury of leg somatotopy of a CST was demonstrated in a patient with leg weakness following a VP shunt operation.

A Review of Traumatic Axonal Injury following Whiplash Injury As Demonstrated by Diffusion Tensor Tractography

Whiplash is a bony or soft tissue injury resulting from an acceleration–deceleration energy transfer in the neck. Although patients with whiplash injury often complain of cerebral symptoms, and previous studies have reported evidence indicating brain injury, such an association has not been clearly elucidated. Traumatic axonal injury (TAI) is tearing of axons due to indirect shearing forces during acceleration, deceleration, and rotation of the brain or to direct head trauma. Diffusion tensor imaging (DTI) has a unique advantage to detect TAI in patients whose conventional brain CT or magnetic resonance imaging (MRI) results were negative following head trauma. Since the introduction of DTI, six studies using diffusion tensor tractography (DTT) based on DTI data have reported TAI in patients with whiplash injury, even though conventional brain CT or MRI results were negative. A precise TAI diagnosis in whiplash patients is clinically important for proper management and prognosis. Among the methods employed to diagnose TAI in the six previous studies, the common diagnostic approach for neural tract TAI in individual patients with whiplash injury were (1) whiplash injury history due to car accident; (2) development of new clinical symptoms and signs after whiplash injury; (3) evidence of neural tract TAI in DTT results, mainly via configurational analysis; and (4) coincidence of newly developed clinical manifestations and the function of injured neural tracts. All six studies were individual patient case studies; therefore, further prospective studies involving larger number of subjects should be encouraged.

Recovery of an injured corticofugal tract from the supplementary motor area in a patient with traumatic brain injury: A case report

RATIONALE

We report on a patient with traumatic brain injury who showed motor recovery concurrent with recovery of injured corticofugal tracts (CFTs), diagnosed by diffusion tensor tractography (DTT).

PATIENT CONCERNS

Four weeks after onset, when the patient started rehabilitation, he showed severe weakness of both upper and lower extremities [Motricity Index (MI, full score: 100/100): 9/30].

DIAGNOSES

A 29-year-old male patient underwent conservative management for traumatic hemorrhages in both frontal lobes and right thalamus resulting from a car accident.

INTERVENTIONS

The patient participated in a comprehensive rehabilitative management program, including movement therapy, dopaminergic drugs for improvement of apraxia (pramipexole: 2.5mg, amantadine: 300mg, ropinirole: 0.75 mg, and levodopa: 500mg), and neuromuscular electrical stimulation therapy of the right elbow extensors, finger extensors, both knee extensors, and ankle dorsiflexors.

OUTCOMES

After 2 months' intensive rehabilitation, his motor weakness rapidly recovered to the point that he was able to move all 4 extremities against some resistance (MI: 75/75). The right supplementary motor area (SMA)-CFT showed narrowing and partial tearing in the upper portion on 1-month DTT, and became thicker on 3-month DTT. Compared to the 12 normal control subjects, the fractional anisotropy (FA) values of the right corticospinal tract and both dorsal premotor cortex-CFT were more than 1 standard deviation lower than those of normal control subjects on both 1- and 3-month DTTs.

LESSONS

Although the tract volume of the right SMA-CFT was more than 1 standard deviation lower than normal control subjects on 1-month DTT, it increased to within 1 standard deviation on 3-month DTT. Recovery of the injured SMA-CFT concurrent with motor recovery was demonstrated in a patient with traumatic brain injury.

Aberrant Anterior Thalamic Radiation Structure in Bipolar Disorder: A Diffusion Tensor Tractography Study

Disrupted white matter (WM) integrity in the anterior thalamic radiation (ATR) has been identified in individuals with bipolar disorder (BD). We explored whether structural WM aberration in the ATR could be visually evaluated by diffusion tensor tractography (DTT). The study comprised 114 participants, including 57 patients with BD and 57 healthy controls (HCs). A poorly visualized ATR reflects an abnormal WM structure. We defined a poorly visualized ATR as one in which at least one ATR fiber bundle failed to reach to the boundary between gray and white matter. Poor ATR visualization occurred significantly more frequently in the left ATR of those with BD than in HCs (P = 0.042). Furthermore, we adjusted the fractional anisotropy (FA) value and when evaluation of a given ATR changed from good to poor, we defined that value as the optimal FA threshold. In the right ATR, we successfully classified BD and HCs with 71.1% accuracy (sensitivity = 89.5% and specificity = 52.6%) and an area under the curve of 0.76 using the optimal FA threshold of 0.28. The present results suggest that the optimal FA threshold can serve as a biological marker that distinguishes individuals with BD from HCs. Thus, visual evaluation of the ATR by DTT may prove to be a useful adjunctive diagnostic tool for BD in clinical practice.

Structural neural connectivity of the vestibular nuclei in the human brain: a diffusion tensor imagingS study

Many animal studies have reported on the neural connectivity of the vestibular nuclei (VN). However, little is reported on the structural neural connectivity of the VN in the human brain. In this study, we attempted to investigate the structural neural connectivity of the VN in 37 healthy subjects using diffusion tensor tractography. A seed region of interest was placed on the isolated VN using probabilistic diffusion tensor tractography. Connectivity was defined as the incidence of connection between the VN and each brain region. The VN showed 100% connectivity with the cerebellum, thalamus, oculomotor nucleus, trochlear nucleus, abducens nucleus, and reticular formation, irrespective of thresholds. At the threshold of 5 streamlines, the VN showed connectivity with the primary motor cortex (95.9%), primary somatosensory cortex (90.5%), premotor cortex (87.8%), hypothalamus (86.5%), posterior parietal cortex (75.7%), lateral prefrontal cortex (70.3%), ventromedial prefrontal cortex (51.4%), and orbitofrontal cortex (40.5%), respectively. These results suggest that the VN showed high connectivity with the cerebellum, thalamus, oculomotor nucleus, trochlear nucleus, abducens nucleus, and reticular formation, which are the brain regions related to the functions of the VN, including equilibrium, control of eye movements, conscious perception of movement, and spatial orientation.

Restoration of the corticoreticular pathway following shunt operation for hydrocephalus in a stroke patient

RATIONALE

We report on a stroke patient who showed restoration of discontinued corticoreticular pathways (CRPs) on serial diffusion tensor tractography (DTT) concurrent with recovery of gait disturbance following shunt operation for hydrocephalus.

PATIENT CONCERNS

A 67-year-old female patient underwent stereotactic drainage for management of intraventricular hemorrhage due to a rupture of the left posterior communicating artery.

DIAGNOSES

After 4 weeks from onset, the patient exhibited quadriparesis with more severe weakness in the proximal muscles and could not even stand or walk. She underwent comprehensive rehabilitation for 3 weeks. Her quadriparesis, as a result of hydrocephalus, did not improve significantly.

INTERVENTIONS

On the pre-op DTT, discontinuations (the right CRP: at subcortical white matter level, and the left CRP: at the midbrain level) of the CRP fibers from the premotor cortex were observed in both hemispheres.

OUTCOMES

She underwent a ventriculo-peritoneal shunt operation and her quadriparesis improved, especially the proximal muscles. Consequently, she could walk with mild assistance on an even floor at 5 days and walk on stairs at 4 weeks after the shunt operation. On the post-op DTT, the discontinued CRP fibers were elongated to the premotor cortex in both hemispheres.

LESSONS

Restoration of discontinued CRPs concurrent with recovery of gait disturbance following shunt operation for hydrocephalus was demonstrated in a stroke patient.

Degeneration of the corticofugal tract from the secondary motor area in a Parkinson's disease patient with limb-kinetic apraxia: A case report

RATIONALE

In this case report, we describe a Parkinson's disease (PD) patient with limb-kinetic apraxia (LKA) in whom degeneration of the corticofugal tract (CFT) from the supplementary motor area (SMA) was observed in diffusion tensor tractography (DTT).

PATIENT CONCERNS

A 63-year-old woman presented with a loss of dexterity in both upper extremities, which indicated LKA, and typical PD-related symptoms, including a gait disturbance with a short step, resting tremor in both upper extremities, and rigidity, and these symptoms had been present for 2 years. The F-florinated-N-3-fluoropropyl-2-β-carboxymethoxy-3-β-(4-lodophenyl) nortropane positron emission tomography scanning findings were consistent with PD. Based on the clinical symptoms and imaging findings, we diagnosed the patient with PD. In a coin-rotation test that was used to evaluate the severity of the LKA, the patient's results significantly decreased compared to the results of the normal controls.

DIAGNOSES

The DTT showed that the CFTs from the SMAs in both hemispheres were partially torn and thinned. The fractional anisotropy values and CFT volumes in both SMAs were >2 standard deviations lower than those of the normal controls.

INTERVENTIONS

The patient was treated with an initial dose of 150/37.5 mg/day of levodopa/benserazide, and the dose was gradually increased to 400/100 mg/day.

OUTCOMES

After treatment, although the bradykinesia, rigidity, and resting tremor of the patient significantly decreased, the dexterity of the patient's hands did not improve.

LESSONS

These observations indicated degeneration of the CFTs from the SMAs in both hemispheres in the patient. This degeneration might have, at least in part, contributed to the patient's LKA. The results of this study suggest that CFT degeneration could be one of the pathological mechanisms underlying LKA in patients with PD.

Gait recovery by activation of the unaffected corticoreticulospinal tract in a stroke patient: A case report

RATIONALE

A 50-year-old man presented with complete paralysis at the onset of a putaminal hemorrhage.

PATIENT CONCERNS

The patient presented with complete paralysis of the left upper and lower extremities (Medical Research Council:0/5).

DIAGNOSES

Spontaneous intra crebral hemorrhage on putamen.

INTERVENTION

He underwent comprehensive rehabilitative therapy from 3 weeks after onset. At 3weeks after onset, he presented with severe weakness of the left extremities. The weakness of his left extremities had recovered as follows at 3 months after onset. Consequently, he was able to walk independently on an even floor.

OUTCOMES

On 3-week and 3-month diffusion tensor tractography (DTTs), the right corticospinal tract (CST) and the corticoreticulospinal tract (CRT) showed discontinuations below the lesion. On 3-month DTT, the left CST had become thinner; however, the left CRT had become thicker compared with 3-week DTT (Fig. 1).

LESSONS

To the best of our knowledge, this is the first study to demonstrate the activation process of the CRT in the unaffected hemisphere in relation to gait recovery from early to chronic stage of stroke.

Delayed degeneration of the left fornical crus with verbal memory impairment in a patient with mild traumatic brain injury: A case report

RATIONALE

We report on a patient who showed delayed degeneration of the left fornical crus with verbal memory impairment following mild traumatic brain injury (TBI), which was demonstrated by diffusion tensor tractography (DTT). PATIENT CONCERNS:: fter flexion and hyperextension of her head to the opposite side, the patient experienced a dazed feeling for a while at the time of head trauma. The patient's Glasgow Coma Scale score was 15, and mini-mental state examination score was 30.

DIAGNOSES

A 50-year-old right-handed female with 12 years of education suffered from head trauma resulting from a car accident.

INTERVENTIONS

A The patient showed normal memory function at one year after onset: the Memory Assessment Scale (global memory: 124 (95 percentile (%ile)), verbal memory: 111 (77%ile), and visual memory: 132 (98%ile) (A percentile is a measure used in statistics indicating the value below which a given percentage of observations in a group of observations fall). However, the patient began to experience decline of memory function such as forgetfulness at approximately 1.5 years after onset. On the 2-year evaluation, she showed decrement of memory function (global memory: 108 (70%ile), verbal memory: 86 (18%ile), and visual memory: 129 (97%ile).

OUTCOMES

On 1-year DTT, the integrity of the fornix was well preserved between the fornical column and fornical crus. However, on 2-year DTT, a discontinuation was observed in the left fornical crus.

LESSONS

Delayed degeneration of the left fornical crus was demonstrated in a patient who showed delayed onset of verbal memory impairment following mild TBI.

Recovery of akinetic mutism and injured prefronto-caudate tract following shunt operation for hydrocephalus and rehabilitation: A case report

RATIONALE

A 76-year-old female patient was diagnosed with an aneurysmal subarachnoid hemorrhage following rupture of a right posterior communicating artery aneurysm.

PATIENT CONCERNS

She was treated surgically with clipping of the aneurysmal neck. Six months after onset, when starting rehabilitation at our hospital, she showed no spontaneous movement or speech. DIAGNOSES:: aneurysmal subarachnoid hemorrhage following rupture of a right posterior communicating artery aneurysm.

INTERVENTIONS

During 2 months' rehabilitation, her AM did not improve significantly. As there was no apparent change, she underwent a ventriculo-peritoneal shunt operation for hydrocephalus 8 months after her stroke. After the surgery, she remained in the AM state, but participated in a comprehensive rehabilitative management program similar to that before shunt operation. During 1 month's intensive rehabilitation, her AM gradually improved. At 9 months after onset, she became able to perform some daily activities by herself including eating, washing, and dressing. In addition, she could speak with some fluency.

OUTCOMES

On 6-month DTT, the neural connectivity of the caudate nucleus (CN) to the medial prefrontal cortex (PFC, Broadmann area [BA]: 10 and 12) and orbito-frontal cortex (BA 11 and 13) was low in both hemispheres. However, the neural connectivity of the CN to the medial PFC increased on both sides on 9-month DTT. The integrity of the arcuate fasciculus (AF) was preserved in both hemispheres on both 6- and 9-month DTTs.

LESSONS

Recovery of AM and injured PCTs was observed in a stroke patient.

Severe disinhibition due to injuries of neural tracts related to emotion circuit in a patient with traumatic brain injury: A case report

RATIONALE

Approximately 30% of patients with traumatic brain injury (TBI) develop disinhibition, a condition that involves several brain structures, including the amygdala, orbitofrontal cortex (OFC), and anterior cingulate cortex (ACC). Using diffusion tensor tractography (DTT), we report on a patient with severe disinhibition and injuries of the amygdala, OFC, and ACC following TBI.

PATIENT CONCERNS

A 27-year-old male patient suffered an in-car accident.

DIAGNOSES

Since the onset of the TBI, the patient showed severe disinhibition including violence, as follows: 1) he sometimes attacked therapists and nurses with no provocation, 2) while he was laying on a bed, he shouted and kicked the bed when asked questions, and 3) during therapy with a difficult task, he behaved violently to a therapist. The subscale of disinhibition in Neuropsychiatric Inventory scored three points for severity and for distress.

INTERVENTIONS

N/A.

OUTCOMES

On 10-month DTT, the connectivity of amygdala to the prefrontal cortex including the medial prefrontal cortex and OFC had decreased in both hemispheres. In the prefronto-thalamic tracts, the orbitofronto-thalamic tractshad narrowed (the right hemisphere), and were non-reconstructed (the left hemisphere). Discontinuations of both anterior cingulums were observed in both hemispheres.

LESSONS

Using DTT, concurrent injuries of the amygdala, OFC, and ACC were demonstrated in a patient with severe disinhibition following TBI. Our result suggests the need to assess these neural structures in patients with disinhibition after brain injury.

Limb-kinetic apraxia in a patient with mild traumatic brain injury: A case report

RATIONALE

We report on a patient who developed limb-kinetic apraxia (LKA) due to an injured corticofugal tract (CFT) from the secondary motor area following mild traumatic brain injury (TBI), demonstrated on diffusion tensor tractography (DTT).

PATIENT CONCERNS

She was struck in the right leg by a sedan at a crosswalk and fell to the ground. She lost consciousness and experienced post-traumatic amnesia for approximately ten minutes. She was obliged to wear a cast for a left humerus fracture for two months, and she found she could not move her left hand quickly with intention after removal of the cast; consequently her left hand was almost non-functional. When she visited the rehabilitation department of a university hospital two years after the crash, she had mild weakness of the left upper extremity (manual muscle test: 4/5). However, the movements of the left hand were slow, clumsy, and mutilated when executing grasp-release movements of her left hand.

DIAGNOSES

A 44-year-old female suffered head trauma resulting from a pedestrian car accident.

INTERVENTIONS

When she extended all her left fingers, it took approximately eight seconds at her fastest speed to perform the pattern extending from the thumb to little finger sequentially.

OUTCOMES

On two-year DTT, narrowing and partial tearing was observed in the right supplementary motor area (SMA)-CFT.

LESSONS

Injury of the right SMA-CFT was demonstrated in a patient with LKA in a hand following mild TBI. Our results stress the need to evaluate the CFTs from the secondary motor area for patients with unexplained motor execution problems following mild TBI.

Recovery of injured Broca's portion of arcuate fasciculus in the dominant hemisphere in a patient with traumatic brain injury

RATIONALE

Recovery of injured AF in patients with traumatic brain injury (TBI) has not been reported. In this study, we report on a patient with TBI who recovered from an injury to Broca's portion of AF in the dominant hemisphere, diagnosed by diffusion tensor tractography (DTT).

PATIENT CONCERNS

A 28-year-old right-handed male patient suffered head trauma resulting from sliding while riding a motorcycle.

DIAGNOSES

He was diagnosed with a traumatic contusional hemorrhage in the left frontal lobe, subarachnoid hemorrhage, and subdural hemorrhage in the left fronto-temporal lobe.

INTERVENTIONS

He underwent craniectomy on the left fronto-temporal area, and hematoma removal for the subdural hemorrhage in the neurosurgery department of a university hospital. Two weeks after the injury, he was transferred to the rehabilitation department of another university hospital. He showed severe aphasia and brain MRI showed leukomalactic lesion in the left frontal lobe.

OUTCOMES

The result WAB for the patient showed severe aphasia, with an aphasia quotient of 45.3 percentile. However, his aphasia improved rapidly by 9 months with an aphasia quotient at the 100.0 percentile. 2-week DTT detected discontinuity in the subcortical white matter at the branch to Broca's area of left AF. By contrast, on 9-month DTT, the discontinued portion of left AF was elongated to the left Broca's area.

LESSONS

Recovery of injured Broca's portion of AF in the dominant hemisphere along with excellent improvement of aphasia was demonstrated in a patient with TBI. This study has important implications in brain rehabilitation because the mechanism of recovery from aphasia following TBI has not been elucidated.

Diffusion tensor tractography studies on mechanisms of recovery of injured fornix

The fornix, which connects the medial temporal lobe and the medial diencephalon, is involved in episodic memory as an important part of the Papez circuit. The mechanisms of recovery of an injured fornix revealed by diffusion tensor tractography in the five studies are summarized as follows: 1) recovery through the nerve tract from an injured fornical crus to the medial temporal lobe via the normal pathway of the fornical crus; 2) recovery through the nerve tract originating from an ipsi-lesional fornical body connected to the ipsi-lesional medial temporal lobe via the splenium of the corpus callosum; 3) recovery through the nerve tract from the ipsi-lesional fornical body extending to the contra-lesional medial temporal lobe via the splenium of the corpus callosum; 4) recovery through the nerve tract originating from the ipsi-lesional fornical column connected to the ipsi-lesional medial temporal lobe; and 5) recovery through the nerve tract originating from the contra-lesional fornical column connected to the ipsi-lesional medial temporal lobe via the contra-lesional medial temporal lobe and the splenium of the corpus callosum. These diffusion tensor tractography studies on mechanisms of recovery of injured fornical crus appeared to provide useful information for clinicians caring for patients with brain injury, however, studies on this topic are still in the beginning stages.

Enhanced White Matter Integrity in Corpus Callosum of Long-Term Brahmakumaris Rajayoga Meditators

Meditation has a versatile nature to affect cognitive functioning of human brain. Recent researches demonstrated its effects on white matter (WM) properties of human brain. In this research, we aim to investigate WM microstructure of corpus callosum (CC) in long-term meditators (LTMs) of rajayoga meditation using diffusion tensor imaging. For this cross-sectional analysis, 22 LTMs and 17 control participants of age ranging from 30 to 50 years were recruited. Results show high fractional anisotropy values with low mean diffusivity in whole as well as different segments of CC in the LTM group. Also the experience of meditation was correlated with WM properties of CC tracts. Findings may suggest rajayoga meditation to bring potential changes in microstructure of CC segments. Further studies are suggested in clinical population to check its validity and efficacy against disorders involving agenesis of WM.