Aging of reward dopamine tracts in the human brain: A diffusion tensor imaging study.

The mesocortical tract (MCT) and mesolimbic tract (MLT) are reward dopaminergic tracts that have been shown to play a role in regulating reward stimuli, including both incentive salience and social stimuli. In the current study, we examined aging of the MCT and MLT in normal human participants to explain human brain structures using diffusion tensor tractography (DTT). Sixty-four healthy participants were recruited for this study and allocated to 3 groups based on participants' age. Diffusion tensor imaging was performed, and MCTs and MLTs were reconstructed using the probabilistic tractography method. A significant negative correlation was observed between age and fractional anisotropy and tract volume of the MCT and MLT, whereas a positive correlation was observed between age and mean diffusivity. The mean fractional anisotropy value of the MCT was significantly lower in the old group than in the young and middle-aged groups (P < .05). The mean diffusivity values of the MCT and MLT were significantly higher in the old group than in the young and middle-aged groups (P < .05). The mean tract volume values of the MCT and MLT were significantly lower in the old group than in the young group (P < .05). We found that degenerative changes in the MCT and MLT began in participants in the 20s-30s, progressed steadily throughout life, and accelerated in the 60s.

Neural Injury of the Dopaminergic Pathways in Patients with Middle Cerebral Artery Territory Infarct: A Diffusion Tensor Imaging Study.

The mesocortical tract (MCT) and mesolimbic tract (MLT), dopaminergic pathways originating from the ventral tegmental area in the midbrain to the ventral striatum (nucleus accumbens) and prefrontal cortex, play a crucial role in regulating incentive salience. This study aimed to investigate the potential changes in the MCT and MLT pathways following ischemic stroke, such as middle cerebral artery (MCA) infarction. We enrolled thirty-six patients with MCA infarction and forty healthy individuals with no history of psychiatric or neurological disorders. Using diffusion tensor tractography, we examined the injury to the affected and unaffected MCT and MLT pathways in patients with MCA infarction, comparing them to the control group. Our findings revealed a significant difference in the mean values of fractional anisotropy (FA) and tract volume (TV) of the MCT and MLT pathways between the patient and control groups (p < 0.05). Specifically, the mean FA of the MCT and MLT showed a decrease of 7.94% and 6.33%, respectively, in the affected side compared to the control group (p < 0.05). Similarly, the mean TV of the MCT and MLT showed a decrease of 73.22% and 78.79%, respectively, in the affected side compared to the control group (p < 0.05). These changes were significantly different from those of the unaffected MCT, MLT, and control groups (p < 0.05). Our study suggests that MCA infarction can cause significant damage to the affected MCT and MLT pathways, potentially contributing to our understanding of the pathophysiology of post-stroke depression.

Degeneration of nigrostriatal pathway in patients with middle cerebral infarct: A diffusion tensor imaging study.

The nigrostriatal tract (NST) is a dopaminergic pathway that runs from the substantia nigra pars compacta in the midbrain to the dorsal striatum (caudate nucleus and putamen) and regulates voluntary movement via the basal ganglia motor loops. However, it is unclear whether the effects of ischemic stroke, such as middle cerebral artery (MCA) infarction, are associated with changes in the NST. Thirty MCA infarct patients and 40 healthy subjects with no history of psychiatric or neurological disorders were enrolled in the present study. Diffusion tensor tractography was used to investigate injury to the ipsilesional and contralesional NST in MCA infarct patients compared to the normal human brain. There was a significant difference in the mean fractional anisotropy and tract volume values of the NST between the patient and control groups (P < .05). post hoc analysis revealed that the mean fractional anisotropy and tract volume from the ipsilesional NST showed a significant difference compared with those of the contralesional NST and control groups (P < .05). MCA infarction can lead to damage to the ipsilesional NST, which can impair one's ability to stop unwanted muscular contractions or voluntary movement.

Aging of the mesolimbic tract in the human brain: A diffusion tensor imaging study.

The mesolibic tract (MLT) is a dopaminergic tract that has been shown to play a role in regulating reward stimuli, including both incentive salience and social stimuli. In the current study, we examined the aging of MLT in normal human participants to explain human brain structures using diffusion tensor tractography (DTT). Fifty-seven healthy participants were recruited for this study and allocated to six groups based on their age. Diffusion tensor imaging (DTI) scanning was performed and MLTs were reconstructed using the probabilistic tractography method. MLTs were defined by selecting fibers passing through the seed and target regions of interest placed on the ventral segmental area and nucleus accumbens. A significant negative correlation was observed between age and the voxel number (VN) of MLT, while a positive correlation was observed between age and the apparent diffusion coefficient (ADC). The mean VN value of the MLT was significantly lower in the 60s and 70s age groups than in the 20s, 40s, and 50s (P < .05). The mean ADC value of the MLT was significantly higher in the 60s and 70s groups than in the 20s, 30s, and 40s, 50s groups (P < .05). We found that aging of the MLT began in the 20s or 30s and progressed steadily throughout life until the 60s, when it exhibited significant degeneration. We believe this affect may play a role in the decline of memory and social interaction with aging in normal participants.

Traumatic trigeminal neuropathy after whiplash injury: A case report.

RATIONALE: Many studies using diffusion tensor tractography (DTT) have reported trigeminal neuropathy in various neurological diseases. However, no study on traumatic trigeminal neuropathy following whiplash has been reported. PATIENT CONCERNS: A 51-year old female suffered an indirect head trauma resulting from a flexion-hyperextension injury. At approximately 30 minutes after onset, she began to sense a headache in the left frontal area and sensory changes in the left facial area, signs that intensified with the passage of time. At 7 days after onset, she visited the rehabilitation department of our university hospital and described the characteristics and severity of pain as follows: headache on the left frontal area including the forehead with intermittent squeezing and numbness sensations. Her visual analog scale pain score was 6 with her left cheek having a continuous, dull, swelling sensation (visual analog scale score: 1). On neurological examination, she revealed mild allodynia without hyperalgesia or somatosensory change on the head, cheek, tongue, and oral cavity. DIAGNOSIS: Diffusion tensor imaging data were acquired 7 days after onset. On DTT, the left trigeminal nerve showed discontinuation in the middle portion compared to that of the right trigeminal nerve. Traumatic trigeminal neuropathy was diagnosed based on her clinical features and DTT findings. INTERVENTION: She was prescribed carbamazepine (200 mg/day) and pregabalin (150 mg/day), and her facial pain was well-controlled to a tolerable level. OUTCOMES: These drugs were stopped after approximately 7 month's administration, however, she did not complain of facial pain. LESSONS: By using DTT, we demonstrated traumatic trigeminal neuropathy in a patient with whiplash. We suggest that DTT would be a useful tool for detection of traumatic trigeminal neuropathy in patients who show clinical features of trigeminal neuropathy following whiplash.

Effects of a 12-Week Diet versus Diet plus Aerobic and Resistance Exercise Program on Acylated and Desacylated Ghrelin, and Ghrelin O-Acyltransferase in Adolescent Girls with Obesity.

This study investigated the effects of a 12-week diet versus diet plus aerobic and resistance exercise programme on acylated ghrelin (AG), desacylated ghrelin (DAG), and ghrelin O-acyltransferase (GOAT) concentrations in girls with obesity. We randomised 30 adolescents with obesity to a 12-week aerobic and resistance exercise group (EG) or a control group (CG). At baseline and at 4, 8, and 12 weeks, we measured their body composition, lipid profile, glucose, AG, DAG, and GOAT concentrations. In the EG, the body fat percentage decreased by 2.37% and was significantly lower than that in the CG. The DAG concentrations significantly increased by 48.3% and 27.4% in the EG and CG, respectively. At 4, 8, and 12 weeks, DAG concentrations were significantly higher in the EG than in the CG. AG concentrations were higher at week 12 than at baseline in both groups. In both groups, the GOAT concentrations increased at weeks 8 and 12; however, no between-group differences were observed in the changes in GOAT concentrations. This study showed increased DAG concentrations and non-significant changes in AG and GOAT concentrations after a 12-week aerobic and resistance exercise programme in girls with obesity. These findings suggest that an aerobic and resistance exercise programme influences appetite-regulating hormones, mainly through changes in DAG concentrations.

Aging of the Nigrostriatal Tract in the Human Brain: A Diffusion Tensor Imaging Study.

Background and Objectives: The loss of dopamine neurons in the nigrostriatal tract (NST) is one of the main pathological features of Parkinson's disease (PD), and degeneration of the NST leads to the motor symptoms observed in PD, which include hypokinesia, tremors, rigidity, and postural imbalance. In this study, we used diffusion tensor tractography (DTT) to investigate the aging of the NST in normal human subjects to elucidate human brain structures. Materials and Methods: Fifty-nine healthy subjects were recruited for this study and allocated to three groups, that is, a 20 to ≤39 year old group (the young group), a 40 to ≤59 year old group (the middle-aged group), and a ≥60 year old group (the old group). DTT scanning was performed, and NSTs were reconstructed using the probabilistic tractography method. NSTs were defined by selecting fibers passing through seed and target regions of interest placed on the substantia nigra and the striatum. Results: A significant negative correlation was observed between age and fractional anisotropy and tract volume (TV) of the NST. Mean TV values of the NST were significantly lower in the old group than in the young and middle-aged groups (p < 0.05). The TV values of the NST were significantly reduced with age for men and women (p < 0.05). Conclusion: We found that aging of the NST began in the 3rd decile and progressed steadily throughout life until old age, when it exhibited significant degeneration. We suspect these results are related to the correlation between the incidence of PD and age.

Recovery of an injured arcuate fasciculus via transcallosal fiber in a stroke patient: A case report.

RATIONALE: We report on a patient whose arcuate fasciculus (AF) and corticobulbar tract (CBT) recovered following an infarct in the middle cerebral artery (MCA) territory, demonstrated on serial diffusion tensor tractography (DTT). PATIENT CONCERNS: The patient showed moderate conduction aphasia on the Western Aphasia Battery with an aphasia quotient of 46.5‰ (spontaneous speech: 35.0‰, auditory comprehension: 36.0‰, and naming: 53.1‰) at 1 month after onset. His aphasia improved with an aphasia quotient of 49‰ (spontaneous speech: 71.0‰, auditory comprehension: 52.0‰, and naming: 59.0‰) at 10 months after onset. DIAGNOSIS: A 44-year-old right-handed male patient presented with aphasia and quadriplegia, which occurred at the onset of an infarct in the left MCA territory. INTERVENTION: Diffusion tensor imaging data were acquired twice (1 month and 10 months after onset). OUTCOMES: On one-month DTT, the discontinuation of the left AF and severe narrowing of the right CBT were observed. However, on ten-month DTT, the left AF was connected to the opposite AF by a new tract that passed through the splenium of corpus callosum, and the right CBT had become thicker. LESSONS: We believe that our results suggest a recovery mechanism of injured AF and CBT in stroke patients.

Long-term recovery from a minimally responsive state with recovery of an injured ascending reticular activating system: A case report.

ABSTRACT: We report on a patient with hypoxic-ischemic brain injury (HI-BI) who showed recovery from a minimally consciousness state over 6 years concurrent with recovery of an injured ascending reticular activating system (ARAS), which was demonstrated on diffusion tensor tractography (DTT).A 31-year-old female patient, who suffered from HI-BI, showed impaired consciousness with a minimally conscious state: intermittently obeying simple motor tasks, such as "please grasp my hand." Her consciousness showed recovery with the passage of time; rapid recovery was observed during the recent 2 years.In the upper ARAS, the neural connectivity to both the basal forebrain and prefrontal cortex had increased on 8-year DTT compared with 1.5-year DTT. In the lower dorsal and ventral ARAS, no significant change was observed between 1.5 and 8 years DTTs.Recovery of an injured ARAS was demonstrated in a patient who showed recovery from a minimally consciousness state over 6 years following HI-BI. Our results suggest the brain target areas for recovery of impaired awareness in patients with disorders of consciousness.

Anatomical location of the spinothalamic tract in the subcortical white matter in the human brain: A diffusion tensor imaging study.

INTRODUCTION: We investigated the anatomical location of the spinothalamic tract and its thalamocortical pathway (STT) in the subcortical white matter in normal subjects, using diffusion tensor tractography (DTT). MATERIALS AND METHODS: The STT was reconstructed using FMRIB software in 40 normal subjects. The most probable locations of the STT were defined as the location on an axial slice of the centrum semiovale (CS), corona radiata (CR), and posterior limb of the internal capsule (PL). RESULTS: The STT was located at an average of 62.66% in the anterior to posterior direction along a horizontal line that passed between the anterior and posterior ends of the brain, and an average of 36.29% lateral from the midline in the CS. In the CR, the STT was located at an average of 79.60% in the anterior to posterior direction along the aforementioned horizontal line, and an average of 36.36% lateral from the midline. In the PL, the STT was located at an average of 83.58% in the anterior to posterior direction along a horizontal line that passed the middle point at the genu of the internal capsule and the posterior endpoint of the putamen, and an average of 69.69% lateral from the midline to the lateral end of the putamen. CONCLUSIONS: We found the precise anatomical location of the STT in the subcortical white matter in the human brain using DTT. We believe that the results of this study will be helpful to clinicians in the neuroscience field.

Injury of the dentato-rubro-thalamic tract in a patient with intentional tremor after mild traumatic brain injury: a case report.

OBJECTIVES: We imaged the dentato-rubro-thalamic tract (DRTT) and cortico-ponto-cerebellar tract (CPCT) using diffusion tensor tractography (DTT) to evaluate the cortico-cerebellar-cortical circuit in a patient with tremor in both hands after mild TBI. We found bilateral DRTT injury in the DTT. METHOD: A 50-year-old male presented with action tremor in both hands 1 week after mild TBI. One month before the visit, the patient had a head injury from a fall on a bus. The patient lost consciousness for 1 min and experienced post-traumatic amnesia for approximately 5 min after the accident. His Glasgow Coma Scale score was 15. The action tremor presented with a frequency of 3 Hz in both hands. No specific lesion was observed with a conventional brain MRI. RESULTS: DTT, performed 1.5 months after TBI, showed that the right DRTT was not reconstructed and the left DRTT had thinned. However, CPCT integrity was well-preserved in both hemispheres. The tremor disappeared after oral treatment with 30 mg/day indenol. The patient's tremor would have been caused by disruption of the bilateral DRTT following mild TBI. CONCLUSION: DRTT and CPCT analysis using DTT would be useful for diagnosing abnormal movement problems, including tremor and ataxia, in patients following mild TBI.

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.

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.

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.

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 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.

Optic radiation injury in patients with aneurismal subarachnoid hemorrhage: A preliminary diffusion tensor imaging report.

Visual field defect is one of the various clinical manifestations in patients with subarachnoid hemorrhage (SAH). Little is known about the pathogenic mechanism of visual field defect in SAH. In the current study, we investigated the diffusion tensor imaging (DTI) finding of the optic radiation in patients with SAH following rupture of a cerebral artery aneurysm. We recruited 21 patients with aneurismal SAH (12 males, 9 females, mean age, 52.67 years; range, 41-68 years) who showed no definite lesion along the visual pathway. Twenty-one age-and sex-matched normal control subjects were also recruited. DTI data were acquired at an average of 5.9 weeks (range: 3-12 weeks) after onset and reconstruction of the optic radiation was performed using DTI-Studio software. The fractional anisotropy value, apparent diffusion coefficient value, and fiber number of the optic radiation were measured. The fractional anisotropy value of the optic radiation was significantly decreased, and the apparent diffusion coefficient value was significantly increased, in patients with aneurismal SAH than in normal control subjects. However, there was no significant difference in the fiber number of the optic radiation between patients with aneurismal SAH and normal control subjects. The decrement of fractional anisotropy value and increment of apparent diffusion coefficient value of the optic radiation in patients with aneurismal SAH suggest optic radiation injury. Therefore, we recommend a thorough evaluation for optic radiation injury in patient with aneurismal SAH.

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.