We report on a stroke patient who showed change of the ascending reticular activating system (ARAS) concurrent with recovery from a vegetative state (VS) to a minimally conscious state (MCS), which was demonstrated on diffusion tensor tractography (DTT). A 59-year-old male patient underwent CT-guided stereotactic drainage 3 times for management of intracerebral hemorrhage and intraventricular hemorrhage. After 4 months from onset, when starting rehabilitation, the patient showed impaired consciousness, with a Glasgow Coma Scale (GCS) score of 6 and a Coma Recovery Scale-Revised score of 2. At 10 months after onset, his GCS score had recovered to 11 with a GRS-R score of 20, and he was able to perform rock-scissors-paper using his right hand according to verbal command. On 10-month DTT, marked increased neural connectivity of the thalamic intralaminar nucleus (ILN) to the cerebral cortex was observed in both prefrontal cortexes and the right thalamus compared with 4-month DTT. However, no significant change was observed in the lower dorsal ARAS between the pontine reticular formation (PRF) and the thalamic ILN. In addition, the reconstructed lower ventral ARAS between the PRF and hypothalamus had disappeared in both hemispheres on 10-month DTT. Change of the ARAS was demonstrated in a stroke patient who showed recovery from a VS to an MCS. It appeared that the prefrontal cortex and thalamus, which showed increased neural connectivity, contributed to recovery from a VS to an MCS in this patient.

The main advantage of diffusion tensor tractography is that it allows the entire neural tract to be evaluated. In addition, configurational analysis of reconstructed neural tracts can indicate abnormalities such as tearing, narrowing, or discontinuations, which have been used to identify axonal injury of neural tracts in concussion patients. This review focuses on the characteristic features of axonal injury in concussion or mild traumatic brain injury (mTBI) patients through the use of diffusion tensor tractography. Axonal injury in concussion (mTBI) patients is characterized by their occurrence in long neural tracts and multiple injuries, and these characteristics are common in patients with diffuse axonal injury and in concussion (mTBI) patients with axonal injury. However, the discontinuation of the corticospinal tract is mostly observed in diffuse axonal injury, and partial tearing and narrowing in the subcortical white matter are frequently observed in concussion (mTBI) patients with axonal injury. This difference appears to be attributed to the observation that axonal injury in concussion (mTBI) patients is the result of weaker forces than those producing diffuse axonal injuries. In addition, regarding the fornix, in diffuse axonal injury, discontinuation of the fornical crus has been frequently reported, but in concussion (mTBI) patients, many collateral branches form in the fornix in addition to these findings in many case studies. It is presumed that the impact on the brain in TBI is relatively weaker than that in diffuse axonal injury, and that the formation of collateral branches occurs during the fornix recovery process. Although the occurrence of axonal injury in multiple areas of the brain is an important feature of diffuse axonal injury, case studies in concussion (mTBI) have shown that axonal injury occurs in multiple neural tracts. Because axonal injury lesions in mTBI patients may persist for approximately 10 years after injury onset, the characteristics of axonal injury in concussion (mTBI) patients, which are reviewed and categorized in this review, are expected to serve as useful supplementary information in the diagnosis of axonal injury in concussion (mTBI) patients.

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). A 28-year-old right-handed male patient suffered head trauma resulting from sliding while riding a motorcycle. He was diagnosed with a traumatic contusional hemorrhage in the left frontal lobe, subarachnoid hemorrhage, and subdural hemorrhage in the left fronto-temporal lobe. 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. 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. 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.

We report on a patient with mild traumatic brain injury (TBI) who was diagnosed with conversion disorder for severe weakness of an arm, which was demonstrated using diffusion tensor tractography (DTT) and transcranial magnetic stimulation (TMS). A 23-year-old right-handed female suffered from head trauma resulting from a pedestrian car accident. She underwent rehabilitative management for memory impairment and central pain. At 14 months after onset, she complained of severe weakness of her right arm, which was detected in the morning after sleeping (right shoulder abductor: 3/5, elbow flexor: 3/5, wrist extensor: 1/5, finger flexor: 1/5, and finger extensor: 1/5). Electromyography study for peripheral neuropathy performed at 2 weeks after onset of weakness showed no abnormality. On a 14-month DTT configuration, the integrities of the left corticospinal tract (CST), supplementary motor area-corticofugal tract (SMA-CFT), and dorsal premotor cortex (dPMC)-CFT were well-preserved. Significant differences were not observed for the fractional anisotropy (FA), mean diffusivity (MD), and tract volume (TV) values of the CST, SMA-CFT, and dPMC-CFT in both hemispheres between the patient and ten right-handed age- and sex-matched normal subjects (p > 0.05). On a 14-month TMS study, MEPs obtained at the right abductor pollicis brevis muscle showed no abnormality. Using DTT and TMS, conversion disorder was demonstrated in a patient with mild TBI, who showed severe weakness of an arm. Our results suggest the usefulness of an evaluation of the CST and CFTs from the secondary motor areas using DTT, and the CST using TMS for patients who complain of motor weakness due to conversion disorder.

Rationale: Neurogenic fever is a non-infectious source of fever in a patient with brain injury, especially hypothalamic injury. We report on a stroke patient with neurogenic fever due to injury of hypothalamus, demonstrated by using diffusion tensor imaging (DTI). Patient concerns: A 28-year-old male patient was admitted to the rehabilitation department of university hospital at 30 months after onset. Brain MRI showed leukomalactic lesions in hypothalamus, bilateral medial temporal lobe, and bilateral basal ganglia. He showed intermittent high body temperature (maximum:39.5°C, range:38.5–39.2°C), but did not show any infection signs upon physical examination or after assessing his white blood cell count and inflammatory enzyme levels such as erythrocyte sedimentation rate and C-reactive protein. In addition, 8 age-matched normal (control) subjects (4 male, mean age: 26.6 years, range: 21–29years) were enrolled in the study. Diagnosis: Intraventricular hemorrhage and intracerebral hemorrhage in the left basal ganglia. Interventions: He underwent extraventricular drainage and ventriculoperitoneal shunting for hydrocephalus. Outcomes: DTI was performed at 30 months after onset, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained for hypothalamus. The FA and ADC values of patient were lower and higher, respectively, by more than two standard deviations from control values. Injury of hypothalamus was demonstrated in a stroke patient with neurogenic fever. Lessions: Our results suggest that evaluation of hypothalamus using DTI would be helpful in patients show unexplained fever following brain injury.