http://informahealthcare.com/bij ISSN: 0269-9052 (print), 1362-301X (electronic) Brain Inj, 2014; 28(11): 1485–1488 ! 2014 Informa UK Ltd. DOI: 10.3109/02699052.2014.930178
CASE STUDY
Changes of an injured fornix in a patient with mild traumatic brain injury: Diffusion tensor tractography follow-up study Han Do Lee & Sung Ho Jang Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Taegu, Republic of Korea
Abstract
Keywords
Background: This study investigated the changes of an injured fornix from early stage to chronic stage in a patient with mild traumatic brain injury (TBI), using diffusion tensor tractography (DTT). Methods: A 25-year-old female suffered from head trauma resulting from a pedestrian car accident. The patient showed a total score of 86 for memory impairment on the Memory Assessment Scale at 2 weeks after onset; however, her memory has been recovered to within normal range, with a score of 105 at 9 months after onset. Results: The middle portion of the right fornical crus showed narrowing and the discontinued left fornical crus was shortened on 9-month DTT compared with 2-week DTT. Two branches from the right fornical column and body were observed on 9-month DTT; in contrast, the two branches from the left fornical column and the left fornical body were elongated and shortened, respectively, on 9-month DTT compared with 2-week DTT. Conclusions: The narrowed lesion in the middle of the right fornical crus and the shortening of the discontinued left fornical crus appear to indicate degeneration following traumatic axonal injury. In contrast, the neural branches from both fornices appear to be related to the functional recovery mechanisms of the injured fornix.
Brain plasticity, diffusion tensor imaging, fornix, memory, traumatic brain injury
Introduction In the human brain, many neural tracts are involved in memory function [1]. Among these neural tracts, the fornix is involved in the transfer of episodic memory as a part of the Papez circuit between the medial temporal lobe and the mamillary body [1]. Diffusion tensor tractography (DTT), which is derived from diffusion tensor imaging (DTI), enables three-dimensional visualization and estimation of the fornix [2, 3]. Many studies have reported on injury of the fornix in various brain pathologies [4–9]. However, fewer studies have demonstrated degeneration or recovery of an injured fornix after brain injury [10, 11]. Follow-up DTT study for an injured fornix from early stage to chronic stage after head injury would be useful in elucidating the mechanism of degeneration or recovery of an injured fornix. However, only few studies using DTT for study of changes of an injured fornix have been reported and little is known about these kinds of changes of an injured fornix on DTT [7, 11]. It was hypothesized that follow-up DTT could clarify the process of
Correspondence: Sung Ho Jang, MD, Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University 317-1, Daemyungdong, Namku, Taegu, 705-717, Republic of Korea. Tel: 82-53-620-3269. Fax: 82-53-620-3269. E-mail: strokerehab@ hanmail.net
History Received 13 November 2013 Revised 15 April 2014 Accepted 28 May 2014 Published online 23 June 2014
neural degeneration or neural re-organization of an injured fornix. This study, using follow-up DTT, attempted to investigate the changes of an injured fornix from early stage to chronic stage in a patient with mild TBI.
Case report A 25-year-old female suffered from head trauma resulting from a pedestrian car accident. The patient did not lose consciousness or experience post-traumatic amnesia from the time of the accident. The Glasgow Coma Scale score of the patient was 15. No specific lesion was observed on brain MRI (T1-weighted, T2-weighted and Fluid attenuated inversion recovery (FLAIR) images) performed at 2 weeks and 9 months after onset (Figure 1a). The patient showed memory impairment at 2 weeks after onset: Wechsler Adult Intelligence Scale ¼ 97, and the Memory Assessment Scale (global memory ¼ 86 (18%ile), short-term memory ¼ 81 (10%ile), verbal memory ¼ 87 (19%ile) and visual memory ¼ 94 (35%ile)) [12, 13]. The patient underwent a rehabilitative management programme, including cognitive therapy and medications (choline alfoscerate 3 T/day and dompezile 5 mg) at the outpatient clinic. Her memory impairment had recovered to normal range at 9 months after onset: Wechsler Adult Intelligence Scale: 108, and the Memory Assessment Scale (global memory ¼ 105 (63%ile),
1486
H. D. Lee & S. H. Jang
Brain Inj, 2014; 28(11): 1485–1488
Figure 1. (a) T2-weighted brain MR images taken at 2 weeks after onset show no abnormal lesions (left). Results of diffusion tensor tractography (DTT) at 2 weeks after onset (right). The right fornix was connected from the right mamillary body to the right medial temporal lobe. In contrast, the left fornical crus showed discontinuation before insertion into the left medial temporal lobe (blue arrow). In addition, two neural branches were observed: a branch originating from the left fornical column extended toward the left medial temporal lobe and a branch originating from the posterior end of the left fornical body extended through the splenium of the corpus callosum. (b) T2-weighted brain MR images taken at 9 months after onset show no abnormal lesions (left). Results of DTT at 9 months after onset (right). In the right fornix, the middle portion of the right fornical crus showed narrowing compared with 2-week DTT and two new branches were observed; a branch originating from the right fornix column extended toward the left medial temporal lobe (red arrow) and another branch originating from the right fornix extended through the splenium of the corpus callosum (violet arrow). In contrast, in the left fornix, the discontinued fornical column was shortened (blue arrow). In addition, the two branches from the left fornix showed changes on 2-week DTT: the branch from the left fornical column was elongated (green arrow) and the branch from the left fornical body was shortened. (c) Results of diffusion tensor tractography of six normal control subjects: both fornices are connected from the mammillary body to the medial temporal lobe.
short-term memory ¼ 87 (19%ile), verbal memory ¼ 95 (37%ile) and visual memory ¼ 114 (83%ile)) [12, 13]. Six age-matched control subjects (two male; mean age ¼ 27.0 years, range ¼ 21–29) with no history of
neurologic disease were recruited for comparison of the configuration of the fornix. All subjects (the patient and control subjects) provided written informed consent and the study protocol was approved by the institutional review board.
Changes of an injured fornix in mild TBI
DOI: 10.3109/02699052.2014.930178
Diffusion tensor imaging DTI was performed two times (two weeks and nine months after onset) using a 6-channel head coil on a 1.5 T Philips Gyroscan Intera (Philips, Ltd, Best, The Netherlands) with single-shot echo-planar imaging. For each of the 32 noncollinear, diffusion-sensitizing gradients, 70 contiguous slices were acquired parallel to the anterior commissure–posterior commissure line. Imaging parameters were as follows: acquisition matrix ¼ 96 96, reconstructed to matrix ¼ 192 192, field of view ¼ 240 240 mm2, TR ¼ 10 726 ms, TE ¼ 76 ms, parallel imaging reduction factor (SENSE factor) ¼ 2, EPI factor ¼ 49, b ¼ 1000 s mm2, NEX ¼ 1 and slice thickness ¼ 2.5 mm (acquired isotropic voxel size ¼ 2.5 2.5 2.5 mm3). Fibre tracking was performed using the fibre assignment continuous tracking (FACT) algorithm implemented within the DTI task card software (Philips Extended MR Work Space 2.6). For reconstruction of the fornix, two regions of interest (ROIs) were placed on the midcolumn on an axial image of the colour map and the junction between the body and column on a coronal image of the colour map. Fibre tracking was performed using a fractional anisotropy (FA) threshold of 40.2 and direction threshold 530 . On 2-week DTT, the right fornix was connected from the right mamillary body to the right medial temporal lobe and no unusual branch was observed, which is consistent with those of normal control subjects (Figure 1b and c). In contrast, the left fornical crus showed discontinuation before insertion into the left medial temporal lobe. In addition, two neural branches were observed: (1) a branch originating from the left fornical column extended toward the left medial temporal lobe and (2) a branch originating from the posterior end of the left fornical body extended through the splenium of the corpus callosum. On 9-month DTT, in the right fornix, the middle portion of the right fornical crus showed narrowing compared with 2-week DTT and two new branches were observed; a branch originating from the right fornix column extended toward the left medial temporal lobe and another branch originating from the right fornix extended through the splenium of the corpus callosum. In contrast, in the left fornix, the discontinued fornical column was shortened. In addition, changes in the two branches from the left fornix were observed on 2-week DTT: the branch from the left fornical column was elongated and the branch from the left fornical body was shortened. On DTT of control subjects, both fornices were connected from the mammillary body to the medial temporal lobe.
Discussion The current study investigated changes of the fornix on DTT between 2 weeks and 9 months after onset in a patient with mild TBI. The results were as follows: (1) the middle portion of the right fornical crus showed narrowing and the discontinued left fornical crus was shortened on 9-month DTT compared with 2-week DTT, (2) two branches from the right fornical column and body, which were not observed on 2-week DTT, were observed on 9-month DTT; in contrast, the two branches from the left fornical column and the left fornical body were elongated and shortened, respectively, on
1487
9-month DTT compared with 2-week DTT. On the other hand, this patient showed good recovery of memory impairment; although the patient showed a total score of 86 for memory impairment on the MAS at 2 weeks after onset, her memory has been recovered to within normal range, with a score of 105 at 9 months after onset. It is believed that the changes of the injured fornix in this patient indicated occurrence of degeneration as well as the presence of a mechanism for functional recovery of the injured fornices simultaneously [7]. The narrowed lesion in the middle of the right fornical crus and the shortening of the discontinued left fornical crus appear to indicate degeneration of the injured fornices between 2 weeks and 9 months after onset following traumatic axonal injury of the fornices. However, it is difficult to determine whether the injury of the right fornix could be ascribed to the primary or a secondary traumatic axonal injury [14–16]. On the other hand, the neural branches from both fornices appear to be related to the mechanism for functional recovery of the injured fornix. The appearance of branches originating from the right fornix and the elongation of the branch extended to the medial temporal lobe after originating from the left fornical column might be attributed to recovery of memory impairment in this patient. The finding of these three neural branches coincided with findings of previous studies reporting on the mechanism for recovery of an injured fornix in patients with brain injury [10, 11]. As a result, it is believed that these changes of the fornix might be the result of neural re-organization in response to injury of the fornix. However, this study is limited; it is based on a single case report; thus, it is suggested that conduct of further studies involving large numbers of patients should be encouraged. In addition, limitations of DTT should be considered in interpretation of the results. Although DTT is a good anatomic imaging tool that can demonstrate gross fibre architecture, the presence of kissing fibres in regions of fibre complexity or false positive fibre trajectories may result in under-estimation or over-estimation [17–19].
Conclusion This study investigated changes of an injured fornix in a patient with mild TBI and the findings indicated degeneration of the injured fornix and changes of branches from the injured fornix, suggesting a mechanism for functional recovery of the injured fornix. The results suggest the importance of follow-up DTT study for accurate diagnosis of traumatic axonal injury and investigation of the mechanisms for recovery of an injured fornix. In detail, follow-up DTT study could clarify the process of neural degeneration or re-organization of an injured fornix following TBI. As a result, further follow-up DTT studies might be useful in development of therapeutic strategies to inhibit the neural degeneration or facilitate the neural re-organization after injury of the fornix.
Acknowledgement This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A4A01001873).
1488
H. D. Lee & S. H. Jang
Brain Inj, 2014; 28(11): 1485–1488
Declaration of interest This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A4A01001873).
References 1. Thomas AG, Koumellis P, Dineen RA. The fornix in health and disease: An imaging review. Radiographics 2011;31:1107–1121. 2. Concha L, Gross DW, Beaulieu C. Diffusion tensor tractography of the limbic system. American Journal of Neuroradiology 2005;26: 2267–2274. 3. Yeo SS, Seo JP, Kwon YH, Jang SH. Precommissural fornix in the human brain: A diffusion tensor tractography study. Yonsei Medical Journal 2013;54:315–320. 4. Nakayama N, Okumura A, Shinoda J, Yasokawa YT, Miwa K, Yoshimura SI, Iwama T. Evidence for white matter disruption in traumatic brain injury without macroscopic lesions. Journal of Neurology, Neurosurgery & Psychiatry 2006;77:850–855. 5. Sugiyama K, Kondo T, Higano S, Endo M, Watanabe H, Shindo K, Izumi S. Diffusion tensor imaging fiber tractography for evaluating diffuse axonal injury. Brain Injury 2007;21:413–419. 6. Wang JY, Bakhadirov K, Devous Sr MD, Abdi H, McColl R, Moore C, Marquez de la Plata CD, Ding K, Whittemore A, Babcock E, et al. Diffusion tensor tractography of traumatic diffuse axonal injury. Archives of Neurology 2008;65:619–626. 7. Hong JH, Jang SH. Degeneration of cingulum and fornix in a patient with traumatic brain injury: Diffuse tensor tractography study. Journal of Rehabilitation Medicine 2010;42:979–981. 8. Lee AY, Shin DG, Park JS, Hong GR, Chang PH, Seo JP, Jang SH. Neural tracts injuries in patients with hypoxic ischemic brain
9.
10. 11. 12. 13. 14. 15. 16. 17.
18.
19.
injury: Diffusion tensor imaging study. Neuroscience Letters 2012; 528:16–21. Yeo SS, Choi BY, Chang CH, Jung YJ, Chang MC, Lee DG, Jang SH. Injury of fornix in patients with intracerebral hemorrhage. International Journal of Neuroscience 2012;122: 195–199. Yeo SS, Jang SH. Neural reorganization following bilateral injury of the fornix crus in a patient with traumatic brain injury. Journal of Rehabilitation Medicine 2013;45:595–598. Yeo SS, Jang SH. Recovery of an injured fornix in a stroke patient. Journal of Rehabilitation Medicine 2013;45:1078–1080. Wechsler D. Manual for the wechsler adult intelligence scalerevised. New York: Psychological Corporation; 1981. Williams JM. Memory assessment scales: Professional manual. Odessa, FL: Psychological Assessment Resources; 1991. Povlishock JT, Christman CW. The pathobiology of traumatically induced axonal injury in animals and humans: A review of current thoughts. Journal of Neurotrauma 1995;12:555–564. Blumbergs PC. Changing concepts of diffuse axonal injury. Journal of Clinical Neuroscience 1998;5:123–124. Buki A, Povlishock JT. All roads lead to disconnection?–traumatic axonal injury revisited. Acta Neurochirurgica (Wien) 2006;148: 181–193; discussion 193–184. Lee SK, Kim DI, Kim J, Kim DJ, Kim HD, Kim DS, Mori S. Diffusion-tensor MR imaging and fiber tractography: A new method of describing aberrant fiber connections in developmental CNS anomalies. Radiographics 2005;25:53–65; discussion 66–58. Parker GJ, Alexander DC. Probabilistic anatomical connectivity derived from the microscopic persistent angular structure of cerebral tissue. Philosophical Transactions of the Royal Society of London Series B: Biological Sciences 2005;360:893–902. Yamada K, Sakai K, Akazawa K, Yuen S, Nishimura T. MR tractography: A review of its clinical applications. Magnetic Resonance in Medical Sciences 2009;8:165–174.
Copyright of Brain Injury is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
CASE STUDY
Changes of an injured fornix in a patient with mild traumatic brain injury: Diffusion tensor tractography follow-up study Han Do Lee & Sung Ho Jang Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Taegu, Republic of Korea
Abstract
Keywords
Background: This study investigated the changes of an injured fornix from early stage to chronic stage in a patient with mild traumatic brain injury (TBI), using diffusion tensor tractography (DTT). Methods: A 25-year-old female suffered from head trauma resulting from a pedestrian car accident. The patient showed a total score of 86 for memory impairment on the Memory Assessment Scale at 2 weeks after onset; however, her memory has been recovered to within normal range, with a score of 105 at 9 months after onset. Results: The middle portion of the right fornical crus showed narrowing and the discontinued left fornical crus was shortened on 9-month DTT compared with 2-week DTT. Two branches from the right fornical column and body were observed on 9-month DTT; in contrast, the two branches from the left fornical column and the left fornical body were elongated and shortened, respectively, on 9-month DTT compared with 2-week DTT. Conclusions: The narrowed lesion in the middle of the right fornical crus and the shortening of the discontinued left fornical crus appear to indicate degeneration following traumatic axonal injury. In contrast, the neural branches from both fornices appear to be related to the functional recovery mechanisms of the injured fornix.
Brain plasticity, diffusion tensor imaging, fornix, memory, traumatic brain injury
Introduction In the human brain, many neural tracts are involved in memory function [1]. Among these neural tracts, the fornix is involved in the transfer of episodic memory as a part of the Papez circuit between the medial temporal lobe and the mamillary body [1]. Diffusion tensor tractography (DTT), which is derived from diffusion tensor imaging (DTI), enables three-dimensional visualization and estimation of the fornix [2, 3]. Many studies have reported on injury of the fornix in various brain pathologies [4–9]. However, fewer studies have demonstrated degeneration or recovery of an injured fornix after brain injury [10, 11]. Follow-up DTT study for an injured fornix from early stage to chronic stage after head injury would be useful in elucidating the mechanism of degeneration or recovery of an injured fornix. However, only few studies using DTT for study of changes of an injured fornix have been reported and little is known about these kinds of changes of an injured fornix on DTT [7, 11]. It was hypothesized that follow-up DTT could clarify the process of
Correspondence: Sung Ho Jang, MD, Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University 317-1, Daemyungdong, Namku, Taegu, 705-717, Republic of Korea. Tel: 82-53-620-3269. Fax: 82-53-620-3269. E-mail: strokerehab@ hanmail.net
History Received 13 November 2013 Revised 15 April 2014 Accepted 28 May 2014 Published online 23 June 2014
neural degeneration or neural re-organization of an injured fornix. This study, using follow-up DTT, attempted to investigate the changes of an injured fornix from early stage to chronic stage in a patient with mild TBI.
Case report A 25-year-old female suffered from head trauma resulting from a pedestrian car accident. The patient did not lose consciousness or experience post-traumatic amnesia from the time of the accident. The Glasgow Coma Scale score of the patient was 15. No specific lesion was observed on brain MRI (T1-weighted, T2-weighted and Fluid attenuated inversion recovery (FLAIR) images) performed at 2 weeks and 9 months after onset (Figure 1a). The patient showed memory impairment at 2 weeks after onset: Wechsler Adult Intelligence Scale ¼ 97, and the Memory Assessment Scale (global memory ¼ 86 (18%ile), short-term memory ¼ 81 (10%ile), verbal memory ¼ 87 (19%ile) and visual memory ¼ 94 (35%ile)) [12, 13]. The patient underwent a rehabilitative management programme, including cognitive therapy and medications (choline alfoscerate 3 T/day and dompezile 5 mg) at the outpatient clinic. Her memory impairment had recovered to normal range at 9 months after onset: Wechsler Adult Intelligence Scale: 108, and the Memory Assessment Scale (global memory ¼ 105 (63%ile),
1486
H. D. Lee & S. H. Jang
Brain Inj, 2014; 28(11): 1485–1488
Figure 1. (a) T2-weighted brain MR images taken at 2 weeks after onset show no abnormal lesions (left). Results of diffusion tensor tractography (DTT) at 2 weeks after onset (right). The right fornix was connected from the right mamillary body to the right medial temporal lobe. In contrast, the left fornical crus showed discontinuation before insertion into the left medial temporal lobe (blue arrow). In addition, two neural branches were observed: a branch originating from the left fornical column extended toward the left medial temporal lobe and a branch originating from the posterior end of the left fornical body extended through the splenium of the corpus callosum. (b) T2-weighted brain MR images taken at 9 months after onset show no abnormal lesions (left). Results of DTT at 9 months after onset (right). In the right fornix, the middle portion of the right fornical crus showed narrowing compared with 2-week DTT and two new branches were observed; a branch originating from the right fornix column extended toward the left medial temporal lobe (red arrow) and another branch originating from the right fornix extended through the splenium of the corpus callosum (violet arrow). In contrast, in the left fornix, the discontinued fornical column was shortened (blue arrow). In addition, the two branches from the left fornix showed changes on 2-week DTT: the branch from the left fornical column was elongated (green arrow) and the branch from the left fornical body was shortened. (c) Results of diffusion tensor tractography of six normal control subjects: both fornices are connected from the mammillary body to the medial temporal lobe.
short-term memory ¼ 87 (19%ile), verbal memory ¼ 95 (37%ile) and visual memory ¼ 114 (83%ile)) [12, 13]. Six age-matched control subjects (two male; mean age ¼ 27.0 years, range ¼ 21–29) with no history of
neurologic disease were recruited for comparison of the configuration of the fornix. All subjects (the patient and control subjects) provided written informed consent and the study protocol was approved by the institutional review board.
Changes of an injured fornix in mild TBI
DOI: 10.3109/02699052.2014.930178
Diffusion tensor imaging DTI was performed two times (two weeks and nine months after onset) using a 6-channel head coil on a 1.5 T Philips Gyroscan Intera (Philips, Ltd, Best, The Netherlands) with single-shot echo-planar imaging. For each of the 32 noncollinear, diffusion-sensitizing gradients, 70 contiguous slices were acquired parallel to the anterior commissure–posterior commissure line. Imaging parameters were as follows: acquisition matrix ¼ 96 96, reconstructed to matrix ¼ 192 192, field of view ¼ 240 240 mm2, TR ¼ 10 726 ms, TE ¼ 76 ms, parallel imaging reduction factor (SENSE factor) ¼ 2, EPI factor ¼ 49, b ¼ 1000 s mm2, NEX ¼ 1 and slice thickness ¼ 2.5 mm (acquired isotropic voxel size ¼ 2.5 2.5 2.5 mm3). Fibre tracking was performed using the fibre assignment continuous tracking (FACT) algorithm implemented within the DTI task card software (Philips Extended MR Work Space 2.6). For reconstruction of the fornix, two regions of interest (ROIs) were placed on the midcolumn on an axial image of the colour map and the junction between the body and column on a coronal image of the colour map. Fibre tracking was performed using a fractional anisotropy (FA) threshold of 40.2 and direction threshold 530 . On 2-week DTT, the right fornix was connected from the right mamillary body to the right medial temporal lobe and no unusual branch was observed, which is consistent with those of normal control subjects (Figure 1b and c). In contrast, the left fornical crus showed discontinuation before insertion into the left medial temporal lobe. In addition, two neural branches were observed: (1) a branch originating from the left fornical column extended toward the left medial temporal lobe and (2) a branch originating from the posterior end of the left fornical body extended through the splenium of the corpus callosum. On 9-month DTT, in the right fornix, the middle portion of the right fornical crus showed narrowing compared with 2-week DTT and two new branches were observed; a branch originating from the right fornix column extended toward the left medial temporal lobe and another branch originating from the right fornix extended through the splenium of the corpus callosum. In contrast, in the left fornix, the discontinued fornical column was shortened. In addition, changes in the two branches from the left fornix were observed on 2-week DTT: the branch from the left fornical column was elongated and the branch from the left fornical body was shortened. On DTT of control subjects, both fornices were connected from the mammillary body to the medial temporal lobe.
Discussion The current study investigated changes of the fornix on DTT between 2 weeks and 9 months after onset in a patient with mild TBI. The results were as follows: (1) the middle portion of the right fornical crus showed narrowing and the discontinued left fornical crus was shortened on 9-month DTT compared with 2-week DTT, (2) two branches from the right fornical column and body, which were not observed on 2-week DTT, were observed on 9-month DTT; in contrast, the two branches from the left fornical column and the left fornical body were elongated and shortened, respectively, on
1487
9-month DTT compared with 2-week DTT. On the other hand, this patient showed good recovery of memory impairment; although the patient showed a total score of 86 for memory impairment on the MAS at 2 weeks after onset, her memory has been recovered to within normal range, with a score of 105 at 9 months after onset. It is believed that the changes of the injured fornix in this patient indicated occurrence of degeneration as well as the presence of a mechanism for functional recovery of the injured fornices simultaneously [7]. The narrowed lesion in the middle of the right fornical crus and the shortening of the discontinued left fornical crus appear to indicate degeneration of the injured fornices between 2 weeks and 9 months after onset following traumatic axonal injury of the fornices. However, it is difficult to determine whether the injury of the right fornix could be ascribed to the primary or a secondary traumatic axonal injury [14–16]. On the other hand, the neural branches from both fornices appear to be related to the mechanism for functional recovery of the injured fornix. The appearance of branches originating from the right fornix and the elongation of the branch extended to the medial temporal lobe after originating from the left fornical column might be attributed to recovery of memory impairment in this patient. The finding of these three neural branches coincided with findings of previous studies reporting on the mechanism for recovery of an injured fornix in patients with brain injury [10, 11]. As a result, it is believed that these changes of the fornix might be the result of neural re-organization in response to injury of the fornix. However, this study is limited; it is based on a single case report; thus, it is suggested that conduct of further studies involving large numbers of patients should be encouraged. In addition, limitations of DTT should be considered in interpretation of the results. Although DTT is a good anatomic imaging tool that can demonstrate gross fibre architecture, the presence of kissing fibres in regions of fibre complexity or false positive fibre trajectories may result in under-estimation or over-estimation [17–19].
Conclusion This study investigated changes of an injured fornix in a patient with mild TBI and the findings indicated degeneration of the injured fornix and changes of branches from the injured fornix, suggesting a mechanism for functional recovery of the injured fornix. The results suggest the importance of follow-up DTT study for accurate diagnosis of traumatic axonal injury and investigation of the mechanisms for recovery of an injured fornix. In detail, follow-up DTT study could clarify the process of neural degeneration or re-organization of an injured fornix following TBI. As a result, further follow-up DTT studies might be useful in development of therapeutic strategies to inhibit the neural degeneration or facilitate the neural re-organization after injury of the fornix.
Acknowledgement This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A4A01001873).
1488
H. D. Lee & S. H. Jang
Brain Inj, 2014; 28(11): 1485–1488
Declaration of interest This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A4A01001873).
References 1. Thomas AG, Koumellis P, Dineen RA. The fornix in health and disease: An imaging review. Radiographics 2011;31:1107–1121. 2. Concha L, Gross DW, Beaulieu C. Diffusion tensor tractography of the limbic system. American Journal of Neuroradiology 2005;26: 2267–2274. 3. Yeo SS, Seo JP, Kwon YH, Jang SH. Precommissural fornix in the human brain: A diffusion tensor tractography study. Yonsei Medical Journal 2013;54:315–320. 4. Nakayama N, Okumura A, Shinoda J, Yasokawa YT, Miwa K, Yoshimura SI, Iwama T. Evidence for white matter disruption in traumatic brain injury without macroscopic lesions. Journal of Neurology, Neurosurgery & Psychiatry 2006;77:850–855. 5. Sugiyama K, Kondo T, Higano S, Endo M, Watanabe H, Shindo K, Izumi S. Diffusion tensor imaging fiber tractography for evaluating diffuse axonal injury. Brain Injury 2007;21:413–419. 6. Wang JY, Bakhadirov K, Devous Sr MD, Abdi H, McColl R, Moore C, Marquez de la Plata CD, Ding K, Whittemore A, Babcock E, et al. Diffusion tensor tractography of traumatic diffuse axonal injury. Archives of Neurology 2008;65:619–626. 7. Hong JH, Jang SH. Degeneration of cingulum and fornix in a patient with traumatic brain injury: Diffuse tensor tractography study. Journal of Rehabilitation Medicine 2010;42:979–981. 8. Lee AY, Shin DG, Park JS, Hong GR, Chang PH, Seo JP, Jang SH. Neural tracts injuries in patients with hypoxic ischemic brain
9.
10. 11. 12. 13. 14. 15. 16. 17.
18.
19.
injury: Diffusion tensor imaging study. Neuroscience Letters 2012; 528:16–21. Yeo SS, Choi BY, Chang CH, Jung YJ, Chang MC, Lee DG, Jang SH. Injury of fornix in patients with intracerebral hemorrhage. International Journal of Neuroscience 2012;122: 195–199. Yeo SS, Jang SH. Neural reorganization following bilateral injury of the fornix crus in a patient with traumatic brain injury. Journal of Rehabilitation Medicine 2013;45:595–598. Yeo SS, Jang SH. Recovery of an injured fornix in a stroke patient. Journal of Rehabilitation Medicine 2013;45:1078–1080. Wechsler D. Manual for the wechsler adult intelligence scalerevised. New York: Psychological Corporation; 1981. Williams JM. Memory assessment scales: Professional manual. Odessa, FL: Psychological Assessment Resources; 1991. Povlishock JT, Christman CW. The pathobiology of traumatically induced axonal injury in animals and humans: A review of current thoughts. Journal of Neurotrauma 1995;12:555–564. Blumbergs PC. Changing concepts of diffuse axonal injury. Journal of Clinical Neuroscience 1998;5:123–124. Buki A, Povlishock JT. All roads lead to disconnection?–traumatic axonal injury revisited. Acta Neurochirurgica (Wien) 2006;148: 181–193; discussion 193–184. Lee SK, Kim DI, Kim J, Kim DJ, Kim HD, Kim DS, Mori S. Diffusion-tensor MR imaging and fiber tractography: A new method of describing aberrant fiber connections in developmental CNS anomalies. Radiographics 2005;25:53–65; discussion 66–58. Parker GJ, Alexander DC. Probabilistic anatomical connectivity derived from the microscopic persistent angular structure of cerebral tissue. Philosophical Transactions of the Royal Society of London Series B: Biological Sciences 2005;360:893–902. Yamada K, Sakai K, Akazawa K, Yuen S, Nishimura T. MR tractography: A review of its clinical applications. Magnetic Resonance in Medical Sciences 2009;8:165–174.
Copyright of Brain Injury is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
