Transcallosal fibers from corticospinal tract in patients with cerebral infarct

Abstract

Diffusion tensor image tractography (DTT) can visualize white matter tracts and provide a powerful vehicle with which to investigate the neural pathway at the subcortical level. We attempted to demonstrate the clinical significance of transcallosal fibers (TCF) originating from the corticospinal tract in patients with corona radiata infarct located below the corpus callosum, using diffusion tensor image tractography (DTT). Forty patients with corona radiata infarct located below the corpus callosum and 26 control subjects were enrolled in this study. We classified the DTT findings as follows: no transcallosal fiber from the CST (type A), transcallosal fiber ended in the corpus callosum or connected to the cortex of the opposite hemisphere (type B), and transcallosal fiber that descended toward the lesion after passing through the corpus callosum (type C). Type C indicated that the presence of transcallosal fibers starting from the CST of the unaffected hemisphere was significantly more prevalent in the patients, and these patients showed the poorest motor function. It seems that transcallosal fibers originated from the CST of the unaffected hemisphere, and fibers descending toward the lesion in patients with corona radiata infarct may act to compensate for motor deficits.

Development of the transcallosal motor fiber from the corticospinal tract in the human brain: diffusion tensor imaging study

“…However, no optimal degree of tract turning angle has been reported; instead, TCMF tends to be easily changed by the tract turning angle (Lee et al, 2005). Therefore, we reconstructed the CST using the FA value of 0.2 and compared the incidence of TCMF using three different tract turning angles (45, 60, and 75°), which have been adopted popularly in other studies using DTT for the CST (Jang et al, 2009; Son et al, 2009; Kwon et al, 2011). …”

“…Transcallosal motor fiber (TCMF), which indicates the connection fibers of the corpus callosum between primary motor cortices of the two hemispheres, plays a role in interhemispheric inhibition (IHI) between the two primary motor cortices (Netz, 1999; De Gennaro et al, 2004; Lenzi et al, 2007; Wahl et al, 2007; Wahl and Ziemann, 2008; Jang et al, 2009). IHI has been an important concept in development of the motor system of the brain.…”

“…However, normally developing children and adolescents can represent the associated movements to a various degree depending on the motor task, development of the corpus callosum and maturation of motor control network (Mayston et al, 1999; Hoy et al, 2004; Shim et al, 2008; Koerte et al, 2009; Gasser et al, 2010; Qiu et al, 2010). On the other hand, decrement of IHI following brain injury is a basic mechanism of the contribution of the unaffected motor cortex, which has been regarded as a mechanism for motor recovery (Liepert et al, 2000; Manganotti et al, 2002; Shimizu et al, 2002; Jang et al, 2009; Jang, 2010). Therefore, clarification of the characteristics of IHI and TCMF has been an important topic in neuroscience.…”

“…By contrast, recently developed diffusion tensor tractography (DTT), derived from diffusion tensor imaging (DTI), has a unique advantage in three-dimensional reconstruction of neural tracts by detecting the water diffusion properties (Kunimatsu et al, 2004). Several studies using DTI have reported on TCMF in normal subjects and in patients with brain injury (Wahl et al, 2007; Jang et al, 2009; Koerte et al, 2009; Jang, 2010; Fling et al, 2011, 2012). However, most of these studies focused on the topography of TCMF and little is known about development of TCMF.…”

Both projection and commissural pathways are disrupted in individuals with chronic stroke: investigating microstructural white matter correlates of motor recovery

“…Impairments in M1-M1 and S1-S1 interhemispheric inhibition appear to contribute to motor deficits after stroke [12,14], but the effects of stroke on the integrity of CC motor and sensory fibres and their relation to motor function have not been thoroughly described. Jang et al [15] found that the presence of transcallosal fibers projecting from the unaffected corticospinal tract and descending towards the lesion were associated with poor motor function, but did not specifically evaluate the integrity of fibers within the callosum. Another study demonstrated that transcallosal M1-M1 fibre integrity was reduced in individuals with chronic stroke and that lower integrity of these tracts was associated with less improvement on the Wolf Motor Function Test (WMFT) following 5 consecutive days of non-invasive brain stimulation paired with physical therapy [16].…”