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.

Detection of thinned corticospinal tract and corticoreticular pathway in a patient with a calf circumference discrepancy

In clinical practice, it is challenging to elucidate the location of the lesion in a patient＇s nervous system that is causing the neurologic symptoms, because lesions are often microscopic and cannot be revealed by conventional evaluation methods.

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.

Severe bilateral anterior cingulum injury in patients with mild traumatic brain injury

The cingulum,the neural tract connecting the orbitofrontal cortex with the medial temporal lobe,plays an important role in cognition（Bush et al.,2000）.It is also important in memory because it provides cholinergic innervations to the cerebral cortex after obtaining innervation from the medial septal nucleus,the vertical nucleus of the diagonal band, and the nucleus basalis of Meynert via the medial cholinergic pathway （Nieuwenhuys et al., 2008; Naidich and Duvernoy, 2009; Hong and Jang, 2010a）.

Recovery of an injured ascending reticular activating system with recovery from a minimally conscious state to normal consciousness in a stroke patient: a diffusion tensor tractography study

Consciousnessiscontrolledbytheascendingreticularactivating system (ARAS)(Teasdale and Jennett, 1974;Jang and Lee, 2015;Jang et al., 2016a). Scientific medical strategies for recovery in patients with impaired consciousness are relatively few compared with other diseases.

Impaired consciousness caused by injury of the lower ascending reticular activating system: evaluation by diffusion tensor tractography

A 34-year-old male patient underwent conservative management for traumatic hemorrhage in the right frontal lobe（Figure 1A）.The patient lost consciousness for approximately 4 weeks and experienced post-traumatic amnesia continuously from the time of the accident.The patient’s Glasgow Coma Scale score（Teasdale et al.,1974）was 6

Recovery of multiply injured ascending reticular activating systems in a stroke patient

Consciousness is controlled by ular activating system （ARAS）. lower and upper parts between activation of the ascending retic- The ARAS consists mainly of the the thalamus and cerebral cortex （Edlow et al., 2012; Yeo et al., 2013; Jang et al., 2014）. Because the ARAS is composed of several neuronal circuits connecting the brainstem to the cortex. These neuronal connections begin from the reticular formation （RF） of the brainstem and the intralaminar nucleus of thalamus to the cerebral cortex （Gosseroes et al., 2011）. In addition, the ARAS system also includes several brainstem nuclei （such as dorsal raphe, locus coeruleus, pedun-culopontine nucleus, median raphe and parabrachial nucleus）, non-specific thalamic nuclei, hypothalamus, and basal forebrain （Fuller et al., 2011）.

Injury of the superior longitudinal fasciculus by ventriculoperitoneal shunt:a diffusion tensor tractography study

In this study,we report on a patient who suffered from injury of the superior longitudinal fasciculus following ventriculoperitoneal（VP）shunt operation,which was demonstrated with diffusion tensor tractography（DTT）.An 82-year-old female patient was diagnosed as suffering from normal pressure hydrocephalus（NPH）and underwent VP shunt operation approached through the right posterior parietal area in the brain 3 years ago （Figure 1A）.

Recovery of injured corticoreticulospinal tract following cranioplasty in an ischemic stroke patient: a diffusion tensor tractography study

The corticoreticular pathway(CRP),which mainly mediates proximal and axial muscles,is an important neural tract for gait and postural stability,whereas the corticospinal tract is mainly involved in control of the distal muscles(Jang et al.,2005).Since development of diffusion tensor tractography(DTT),which is derived from diffusion tensor imaging(DTI),a few studies have demonstrated injury of neural tracts following cranioplasty in patients with stroke.In the current study,we report on a stroke patient who underwent decompressive craniectomy showed recovery of the CRP,using DTT.A 48-year-old right-handed male was diagnosed with infarction in the left middle cerebral artery(Figure 1A).

The brain activation pattern of the medial temporal lobe during chewing gum: a functional MRI study

The human brain is known to be influenced by environmental stimuli（Feeney et al.,1982;Kaplan,1988）.Therefore,research on the brain activation pattern by external stimuli has been an important topic in neuroscience（Kaplan,1988）.Chewing gum has been known to have a positive effect on cognition,including alertness,attention,cognitive processing speed,

Injury of the dentatorubrothalamic tract in patients with post-traumatic tremor following mild traumatic brain injury: a case-control study

Post-traumatic movement disorder is one of the sequelae of traumatic brain injury. The dentatorubrothalamic tract(DRTT) is reported to be involved in the control of movement. Therefore, injury of the DRTT can be accompanied by abnormal movements, including ataxia, tremor, or dystonia. We investigated DRTT injuries in 27 patients who showed post-traumatic tremor in at least one of four extremities following mild traumatic brain injury. We classified DRTT injuries based on diffusion tensor tractography parameters and configuration: type A: the DRTT showed narrowing, type B: the DRTT showed partial tearing, and type C: the DRTT showed discontinuation. Fractional anisotropy and fiber number of the DRTT were significantly decreased in patients compared with the healthy controls. Based on our DRTT injury classification, among the 54 hemispheres of the 27 patients, type A injury occurred in 22 hemispheres(40.7%) of 17 patients, type B injury was present in 15 hemispheres(27.7%) of 10 patients, and type C injury was observed in 8 hemispheres(14.8%) of 6 patients. Our results suggest that diffusion tensor tractography-based evaluation of the DRTT would be useful when determining cause of post-traumatic tremor in patients with mild traumatic brain injury. The study protocol was approved by the Institutional Review Board of Yeungnam University Hospital(YUMC-2018-09-007) on September 5, 2018.

Injury of the arcuate fasciculus in a patient with progressive bulbar palsy

The arcuate fasciculus is the neural tract connecting the two major speech centers（Broca’s and Wernicke’s areas）and plays a critical role in language function（Catani and Mesulam,2008）.Injury of this tract can lead to several types of language impairment,including conduction aphasia,Broca’s aphasia,anomic aphasia,and apraxia of speech（Anderson et al.,1999;Bartha and Benke,2003;Catani and Mesulam,2008;Bernal and Ardila,2009;Kim et al.,2011）.

Reorganization of injured anterior cingulums in a hemorrhagic stroke patient

In this study, we reported on a patient who showed a new neural tract between the injured anterior cingu- lums and the basal forebrain, as shown by diffusion tensor tractography （DTT）.

Weak phonation due to unknown injury of the corticobulbar tract in a patient with mild traumatic brain injury: a diffusion tensor tractography study

In this study,we report on a patient who showed weak phonation following mild traumatic brain injury（TBI）,which was demonstrated by diffusion tensor tractography（DTT）.

Gait deterioration due to neural degeneration of the corticoreticular pathway:a case report

The corticoreticular pathway（CRP）mainly mediates proximal and axial muscles and therefore it is an important neural tract for walking（Miyai et al.,2002;Matsuyama et al.,2004;Mendoza and Foundas,2007）.Diffusion tensor tractography（DTT）,derived from diffusion tensor imaging（DTI）,

Appearance of a neural bypass between injured cingulum and brainstem cholinergic nuclei of a patient with traumatic brain injury on follow-up diffusion tensor tractography images

The human brain is known to contain a maximum of eight cholinergic nuclei： the basal forebrain region： the medial septal nucleus （Ch 1）, the vertical nucleus of the diagonal band （Ch 2）, the horizontal limb of the diago- nal band （Ch 3）, and the nucleus basalis of Meynert （Ch 4）; the brainstem： the pedunculopontine nucleus （Ch 5）, the laterodorsal tegmental nucleus （Ch 6）, and the para- bigeminal nucleus （Ch 8）; and the thalamus： the medial habenular nucleus （Ch 7） （Nieuwenhuys et al., 2008; Naidich and Duvernoy, 2009）. The cingulum is the neu- ral tract extending from the orbitofrontal cortex to the medial temporal lobe （Mufson and Pandya, 1984）. The cingulum plays an important role in memory because it is a passage of the medial cholinergic pathway, which pro- vides cholinergic innervations to the cerebral cortex after originating from Ch 1 and Ch 2 as well as Ch 4 （mainly） （Selden et al., 1998; Nieuwenhuys et al., 2008; Hong and lang, 2010）.

Selective verbal memory impairment due to left fornical crus injury in a patient with intraventricular hemorrhage

The fornix, a part of the Papez circuit, transfers information of episodic memory between the medial temporal lobe and the medial diencephalon （Aggleton and Brown, 1999）. The right medial temporal lobe is known to be specialized for visual memory and the left medial temporal lobe for verbal memory （Tucker et al., 1988; Aegleton and Brown, 1999）.

Neural Tract Degeneration Correlates with Functional Impairment in Patients with Anoxic Brain Injury:A Tract-based Spatial Statistics Study

Dear Editor,Anoxic brain injury(ABI)is a devastating event caused by cardiac arrest,chemical exposure,or trauma.Despite recent advances in medical diagnostic techniques and treatments,the survival rate after ABI is still very low.Previous studies have reported that 52.6%-64.0%of people who received cardiopulmonary resuscitation after nontraumatic cardiac arrest die,and 9.0%-18.6%remain in a permanent vegetative state within 28 days of treatment[1,2].