Introduction
Due to advancement in technology various neuroimaging techniques have been developed for mapping human brain connectivity. Various researchers and doctors seek to understand the role that white matter (WM) and other regions of brain play in normal brain function, brain damage, and how they influence human behavior. The most commonly used methods are magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI) (Van Horn et al., 2012). Gage case whereby a “tamping iron” was accidentally lodged into the skull and brain, offers a clear example of understanding how brain damage can affect the behavior and normal functioning of the brain. The authors used Gage’s data obtained from computed tomography (CT) to access the effect of the iron on the brain and damaged that occurred to the white matter and gray matter (GM).
Neo-physiological/ biological components of the case
The iron rod penetrated Gage’s brain when he was working at a construction site causing significant damage to the brain tissue. It pierced through the left check under the zygomatic arch slightly behind the left eyeball. It also passed through the cranial vault below the left forebrain hence penetrating the brain (Van Horn et al., 2012). Medical imaging technology revealed that the grey matter on the left frontal cortical was severed injured and also it extended to the secondary tissues. This could be explained by the fact that he experienced memory deficiencies and failures to plan well. Through atlas mapping studies of human white matter connectome, nerve damage was reported and was linked to Gage’s loss of sight as well as left eyelid ptosis.
Methodology
The authors obtained the original CT data of Gages’ skull and through computational studies they were able to estimate the best-fit rod trajectory across the skull. They then used the MRI and DWI techniques and multimodal analysis to determine the magnitude of acute regional cortical loss and probable extent of damage to other WM pathways (Van Horn et al., 2012). They took measurements of the skull and tamping iron and determined the trajectory paths and network connectivity. They used 110 normal right-handed males between the age of 25 to 36.
Results
They realized that 3.9760.29% of the GM was intersected with the most affected regions being the cortical region (0.25%). The left middle superior and frontal sulcus, left orbital sulcus and gyrus, lateral orbital sulcus, inferior frontal gyrus (orbital), and frontal part of both globular and lateral sulcus of insula. The results showed that the iron rod didn’t pass through the midline contrary to the results of other researchers (Van Horn et al., 2012). The most damage was on the insular cortex and left temporal and left frontal polar. Also, 10.7265.46% of WM was destroyed as well as fiber bundles of the connectivity matrices. Integration studies and segregation studies deficiency revealed a higher path length compared to intact network and lower mean local efficiency. This proved that the Gage’s lesion was severe and it affected white mater connectivity of the left cerebral hemisphere.
Discussion
Various contradictory information regarding damage of the Gage’s brain has been reported since the incidence occurred. Some claim that only the left side was affected while others claim it was both the left and right sides. Van Horn et al. 2012, however, supported the fact that only the left hemisphere was damaged since the midline was not bypassed. Results from this article supports the evidence that the damage was specifically directed to the left frontal lobe with 10% of WM destroyed. In addition, there was alteration of the network connectivity indicating damage to the global network topology such as the basal ganglia, limbic area, and insula of the left hemisphere. The neural system of the brain was hugely destroyed that explains the loss of memory observed with Gage.
An interesting finding was that the small worldness of the tamping iron showed that lesion did not have any effect on network clustering (Van Horn et al., 2012). As such, the unaffected network of the brain maintains its functionality integrity and nodal clustering. Other studies as well have proved that networks are insensitive to lesions and damage occurring to the nodes. Therefore, damage of Gage’s brain network connectivity could be unlikely. However, due to the deleterious effect of lesion on network segregation and integration, sensory-specific changes in connectivity such as blindness is possible. Therefore, these results indicate that iron tamping into Gage’s brain destroyed the limbic, temporal, and central hub structures on the left hemisphere and the effect was spread to network hubs leading to cognitive and symptomatology seen in Gage.
Symptoms of the disorder and treatments
Traumatic brain injury is usually connected with behavioral and social alterations, planning deficits, alteration of social functioning, memory loss, and changes in moods as observed with Phineas Gage. Damage to the network connectivity particularly the uncinated fasciculi affect processing of emotion stimuli. This could be the reason why Gage’s personality was altered. Although this case study did not look at the treatments offered to Gage, a treatment plan for patients undergoing traumatic brain injury has been developed. Empirically-based treatments for this disorder involves specific targeted therapy (Sugden, Kile, Farrimond, Hilty, & Bourgeois, 2006) such as use of amantadine, risperidone, and psychostimulants such as methylene. They improve the symptoms leading to visual attention, less agitation, mood swings as well as attention and increased arousal due to dopaminergic effect. Cholinergic augmentation also has been accepted as a treatment method for cognitive impairment.
The most commonly treatments for traumatic brain injury(TBI) include diuretics, anti-seizure drugs, and coma inducing drugs. Diuretics reduces pressure built-up in the brain. Putting the patient in a coma is crucial since the compressed blood vessels are not able to supply enough oxygen and nutrients to the brain. Treatment for TBI takes several weeks and, therefore, the patients should be monitored often since they take time to stabilize (Sugden, Kile, Farrimond, Hilty, & Bourgeois, 2006). Sometimes symptoms may resolve and within few days they shoot up again. In such cases, the dosage of the drug should be considered carefully. If symptoms worsen the treatment should be changed. For instance, administration of 10 mg of donepezil accelerated the aggressiveness and agitation of the patient. As such, it had to be stopped and administration of 500 mg of Valproic acid (VPA) lowered the intensity of the symptoms.
In severe cases surgery can revert the damage (Sugden, Kile, Farrimond, Hilty, & Bourgeois, 2006). This may involve removal of the clotted blood, repairing skull fractures, and opening a window in the skull. Lastly, rehabilitation of the patient is crucial so that they can relearn the basic skills such as talking, writing, and walking. All these treatments are aimed at controlling the psychiatric symptoms and helping the patients recover. For instance, after treatment Gage recovered from the brain trauma and his mental status stabilized. He was able to take other forms of employment, travel to various countries such as New England, South America, and Western US. Nevertheless, 12 years later he succumbed to epilepsy linked to the white matter connectivity injuries (Van Horn et al., 2012). Although the available treatments alleviate the symptoms of TBI, there is scarcity of information regarding natural recovery. Also, if the brain cells are destroyed completely, there is no repair.
Conclusion
MRI and DWI techniques have played a crucial role neurological disorders studies. The case study of Phineas Gage has contributed hugely to brain studies by offering great insights on what happens when brain is damaged and the pharmacological intervention of diseases causing traumatic brain injury. The iron tamping on Gage’s brain caused direct damage on the left cerebral hemisphere leading to destruction of the white and grey matter. Also, it altered the network hubs and connectivity leading to brain lesions that affected other areas of the brain. As a consequence, the neural system was affected leading to psychological and behavioral changes observed in Gage. This article offers detailed information that eliminates controversies surrounding the Gage case.
References
Sugden, S. G., Kile, S. J., Farrimond, D. D., Hilty, D. M., & Bourgeois, J. A. (2006). Pharmacological intervention for cognitive deficits and aggression in frontal lobe injury. NeuroRehabilitation, 21(1), 3-7.
Van Horn, J. D., Irimia, A., Torgerson, C. M., Chambers, M. C., Kikinis, R., & Toga, A. W. (2012). Mapping connectivity damage in the case of Phineas Gage. PloS one, 7(5), e37454.
