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 followingrupture 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.

Delayed gait recovery in a stroke patient

We report on a stroke patient who showed delayed gait recovery between 8 and 11 months after the onset of intracerebral hemorrhage. This 32-year-old female patient underwent craniotomy and drainage for right intracerebral hemorrhage due to rupture of an arteriovenous malformation. Brain MR images revealed a large leukomalactic lesion in the right fronto-parietal cortex. Diffusion tensor tractography at 8 months after onset revealed that the right corticospinal tract was severely injured. At this time, the patient could not stand or walk despite undergoing rehabilitation from 2 months after onset. It was believed that severe spasticity of the left leg and right ankle was largely responsible, and thus, antispastic drugs, antispastic procedures （alcohol neurolysis of the motor branch of the tibial nerve and an intramuscular alcohol wash of both tibialis posterior muscles） and physical therapy were tried to control the spasticity. These measures relieved the severe spasticity, with the result that the patient was able to stand at 3 months. In addition, the improvements in sensorimotor function, visuospatial function, and cognition also seemed to contribute to gait recovery. As a result, she gained the ability to walk independently on even floor with a left ankle foot orthosis at 11 months after onset. This case illustrates that clinicians should attempt to find the cause of gait inability and to initiate intensive rehabilitation in stroke patients who cannot walk at 3-6 months after onset.

Injury of corticoreticular pathway and corticospinal tract caused by ventriculoperitoneal shunting

Ventriculoperitoneal shunting is a commonly used neurosurgical procedure for management of hydrocephalus（Jang et al.,2015）.Various complications of ventriculoperitoneal shunting have been reported,including infection,hemorrhage,shunt malfunction,shunt displacement and brain swelling（Kwon and Jang,2012,2015）.Although ventriculoperitoneal shunting can cause injury of adjacent neural tracts,little is known about injury of the neural tract by ventriculoperitoneal shunting（Kwon and Jang, 2013）.

Unusual neural connection between injured cingulum and brainstem in a patient with subarachnoid hemorrhage

The human brain is known to have six cholinergic nudei （Selden et al., 1998; Nieuwenhuys et al., 2008）. The cerebral cortex obtains cholinergic innervation mainly from the basalis nucleus of Meynert （Ch 4） in the bas- al forebrain through the medial and lateral cholinergic pathways （Selden et al., 1998; Mesulam et al., 1983）. The cingulum, the neural fiber bundle connecting the basal forebrain and the medial temporal lobe, contains the medial cholinergic pathway （Selden et al., 1998; Hong and Jang, 2010）.

Disappearance of unaffected motor cortex activation by repetitive transcranial magnetic stimulation in a patient with cerebral infarct

The ipsilateral motor pathway from the unaffected motor cortex to the affected extremity is one of the motor recovery mechanisms following stroke （Jang, 2011）. Because stroke patients who had shown recovery by this mechanism usually showed poorer motor function, compared with patients who showed recovery by other mechanisms, several researchers have considered this mechanism as a maladaptive plasticity （]ang, 2013）.

Multiple injuries of the ascending reticular activating system in a stroke patient:a diffusion tensor tractography study

Consciousness is mainly controlled by activation of the ascending reticular activating system（ARAS）.Diffusion tensor tractography（DTT）,which is reconstructed from diffusion tensor imaging（DTI）data.

Unusual neural tract between injured fornix and pedunculopontine nucleus in a patient with traumatic brain injury

It has been known that four cholinergic nuclei are located in the septal region and basal forebrain （Ch 1： medial septal nucleus, Ch 2： vertical nucleus of the diagonal band, Ch 3： horizontal limb of the diagonal band and Ch 4： nucleus basalis of Meynert） and two are located in the brainstem （Ch 5： pedunculopontine nucleus and Ch 6： laterodorsal tegmental nucleus） （Selden et al., 1998; Lucas-Meunier et al., 2003; Mesulam, 2004; Nieuwenhuys et al., 2007）. The fornix transfers information on episodic mem- ory between the medial diencephalon and the medial temporal lobe （Afifi and Bergman, 2005; Wolk and Budson, 2010）. The fornix is known to obtain cholinergic innervation from Ch 1 and Ch 2, and to project to the hippocampal formation （Selden et al., 1998; Lucas-Meunier et al., 2003; Mesulam, 2004; Nieu- wenhuys et al., 2007; Dere et al., 2008; Naidich and Duvernoy, 2009; Isaacson and Pribram, 2013）.

Recovery of the corticospinal tracts injured by subfalcine herniation: a diffusion tensor tractography study

Motor weakness is one of the most serious disabling sequelae of stroke. For successful rehabilitation, thorough estimation of the state of injured neural tracts for motor function is mandatory. After development of diffusion tensor tractogra- phy （DTT）, which is derived from diffusion tensor imaging （DTI）, three-dimensional reconstruction and estimation for three motor tracts, such as the corticospinal tract, the rubrospinal tract, and the corticoreticular pathway became possible （Kunimatsu et al., 2004; Puig et al., 2010; Yang et al., 2011）. The corticospinal tract is known to be a major neural tract for motor function in the human brain （Binkofski et al., 1996）.

Optic radiation injury in a patient with intraventricular hemorrhage: a diffusion tensor tractography study

Optic radiation（OR）injury can occur following various brain injuries and it is usually accompanied by visual field defects（Zhang et al.,2006）.OR is very important for performing activities of daily living and providing safety.