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FALLOUT OF THE RECENT AFFLUENCE IN OMAN- Cajal’s pessimistic views were seriously challenged only Aand the Gulf region in general-is the sharp rise in in the last two decades. We now know not only that there traffic accidents and the consequent head injuries, is continuous growth of brain tissue, but have also begun which render many young people to severe morbidity and to recognize that the brain, when injured, begins a process mortality.l Head injuries result in 10% of global mortal- of healing which involves intrinsic growth, reorganization,
ity and are responsible for more years of life lost than adaptation and environmental interaction that reverses most diseases or medical conditions.2'3 Though Oman is many of the pessimistic connotations of Cajal’s lament. a world leader in health care, facilities for rehabilitation The understanding of the mechanisms of plasticity was of the brain injured remain minimal.4‘6 Until recently an important development.10 Plasticity refers not only to this was understandable and perhaps excusable, since possible cortical changes after injuries but also to a wide experts previously considered it impossible to regenerate variety of biological processes relevant to rehabilitation.11
or anatomically reorganize the adult nervous system, once Among the models and mechanisms suggested to explain damaged.7 This may no longer be the case. Research in plasticity is Vicarience, which infers that different areas of
the nineties-the decade of the brain-has brought new the brain have the potential to take over specific functions insights into the pathophysiology, impairments, functional of damaged tissues. The parallel term in modern neuropsy- limitations and disabilities involved in brain injury. These chology is equipotentiality, the ability of healthy nerve cells may provide a better understanding of the mechanisms of to take over the functions of their damaged counterparts. functional recovery following brain damage, and have kin- Vicarience has been supported by many experiments. dled hopes for more effective rehabilitation.7’ 8 It is instruc- Among these are the longitudinal studies on monkeys and tive to review some of the pertinent medical history and rats by Merzenich et al and more recently, by Al-Adawi.12‘13 then the recent medical progress in our understanding of Following median nerve transection and ligation, the the response of the brain to injury. researchers completely deafferented the animals’ limbs, The belief in irreversibility of neural damage probably thus severing all sensory nerves. Subsequently, ‘new’ inputs goes back to the Spanish anatomist and Nobel Laureate, formed in the brain’s receptive field of deafferented limbs, Santiago Ramony Cajal. In his 1928 book DEGENERA- suggesting that the brain possesses an inherent capacity
TION AND REGENERATION OF THE NERVOUS SYSTEM for reorganization, leading to functional recovery and he declared, ‘Once development is completed, the sources possibly, rehabilitation. Similar reorganization has also of growth and regeneration of axons and dendrites are been reported in humans. Mogilner showed somatotopic irrevocably lost. In the adult brain, nervous pathways are reorganization in two adult subjects who were scanned fixed and immutable; everything may die, nothing is regen- using magnetoencephalography before and after surgical erated’ (p 750).9 For decades, his influential words kept separation of syndactyly (webbed fingers).14 The presur- health planners in inertia under the impression that it was gical maps had displayed shrunken and nonsomatotopic pointless to try to develop training or rehabilitation pro- hand representation. Within weeks of surgery, however, grammes to promote something that could not happen. cortical reorganization occurred up to 39 mm from the site of the original area of representation, reflecting the In addition to these suggested mechanisms of injury new functional status of the separated digits. There are and recovery, another possible mechanism of injury at more experimental and clinical reports that reaffirm the neurochemical level has begun to emerge.22 Experiments mechanism of vicarience.15 Interestingly, neuropsychologi- over the past decades indicate that when a healthy brain cal plasticity, rather than being limited by certain critical is suddenly injured, neurotransmitter activity tends to periods of development, can occur at any age.15 change.23 There is consensus that at the earliest phase of The second popular concept of how recovery might a lesion, the injured, traumatized and dying cells become occur is based on the notion that the brain evolves ‘backup’ unable to control their fluid and ion balance, and release or ‘fail-safe systems’ to be activated when something goes their stores of amino acid neurotransmitters and calcium wrong. This is similar to backup computers or second ions.24 The consequent excitotoxicity weakens and ‘burns brake systems in vehicles, where the standby facility auto- out’ the neurons, which eventually die.19 It is through the matically assumes the functions of the damaged system. understanding of these processes that we now realize that In neuropsychology, such compensatory mechanism is there is a cascade of chemical processes that must occur termed redundancy. In the 197os, Wall and his colleagues for a brain cell to die. The understanding of these processes demonstrated redundancy by showing that previously has given us a realization that there may be a number of silent fibre pathways in the brain stem could become opportunities to affect the process by which cells die, and immediately active when the primary sensory fibres in perhaps by doing so affect the magnitude of the injury the spinal cord were cut.16 Since the appearance of activity itself. While some of the early studies suggest that there occurred soon after the injury, Wall proposed that the new may be a limited window of opportunity during which we pathways were there all the time, but had been masked or may affect these processes, this remains a very fertile area inhibited by the active primary sensory fibres. Redundancy for research and a potentially significant means by which (or unmasking) in the nervous system is often used to we may reduce the morbidity of our patients. explain how a patient can retain function after suffering Each of the areas outlined suggest a response by a major trauma to the brain.17 medicinal/rehabilitation team that, if not pursued, repre- Such recoveries could also be explained as being due to sent a failure of our medical system to apply the knowl- functional substitution, where part of the brain is consid- edge gained over the past decade to the lives of the citizensered ‘reprogrammed’ to take charge of the functions of the who depend on our vigilance. Each advance in knowledge damaged area. Recovery is explained not so much by the invites more than our passive observation. First, as we dis- restoration of normal behaviour as by the development cuss the concept of vicarience, we must not view this as an of alternative behaviour that permit patients to achieve internal process separate from environmental influences. certain goals in everyday life, though not as efficiently as Biernaskie & Corbett have noted that the process of reor- before.18 Examples of functional substitution are demon- ganization seems to be heavily influenced by the stresses on strated by individuals such as physicist Stephen Hawking the organism as it attempts to engage the damaged neural who lost his ability to speak but learned to communicate tissue. 25 For instance, if the damage in the brain results in by using a keyboard. In this conceptual model of rehabili- paralysis of the left arm, it seems the attempt to use the left tation, behavioural substitution is expected to be accom- arm stimulates the organism to more fully reorganize this panied by structural reorganization of the nervous system area of the brain. Without this stress, the reorganization itself.19’20 will be less complete. Efforts in rehabilitation elsewhere The third concept that has received renewed attention is in the world, which have addressed this, have focused on diaschisis, which postulates that when injury or disease has the forced use of the impaired portion of the brain. There disturbed a part, the resultant trauma can affect other quite are entire programs that focus on this forced use concept, distant parts. Diaschisis is thought to be a temporary block which are unique to the process of rehabilitation. of function produced by damage or irritation to brain tis- The second concept discussed suggests that a redun- sue.21 Recent preliminary studies suggest that after injury, dancy of the brain allows for the ‘awakening’ of area of the areas of the brain distant from the actual damage site brain when other primary areas have been injured.A point could become depressed.7 These studies provide evidence that may be lost in these relatively recent discoveries is that that focal subcortical lesions can result in cortical dysfunc- once these areas have been brought “on line” and thus are tion in patients even though the cortex is intact, and vice available for a new function, there is need for this tissue to versa. This may explain why non-specific brain injuries be trained. If we step back and review the development of sometimes lead to impairments. the primary tissue, it is clear that there are years of train-
ng during which this tissue originally obtained its facility With a ‘low child, low adult’ mortality stratum, Oman’s of function. It is not surprising therefore that there needs population has an extremely large youth base, with 65% to be a process of focused ‘rehabilitation’ of this new tissue below 25.33 Recklessness, novelty seeking and proneness to that allows us to maximize its function. accidents peak in adolescence, the underdeveloped frontal Indeed, over the last few years, more cases of func- cortex in young people being cited as one of the many tional recovery after cerebral injury and disease have reasons for this.34 An unusual trend in Oman is reckless been published than anytime before.26 The pathways of driving in young women. Whereas studies from elsewhere neurotransmitters involved have been well charted and the place road traffic accidents in the ‘male turf’, for reasons not safety of the drugs which influence these transmitters has yet apparent, females in Oman have managed to blur such been relatively well established.12 It is important to note demarcation.35 that although these drugs have helped to tease out neu- With the advent of effective emergency care, faster rochemical and pathophysiology behind neurocognitive transportation and acute medical management, the mor- impairment following brain damage, the traditional role of tality rate among the brain-injured has decreased in Oman. retraining and remediation (in other words, rehabilitation) However, merely saving lives and leaving them at that may plays a central role. In a way, the drug appears to kick-start result in a most distressing quality of life for the survivors the system so the retraining or remediation can occur in who are even incapable of self-care.
tandem.” 27 We now know that if an area of the brain has Prevention being infinitely superior to rehabilitation, been injured that there is a change in the neurochemistry the youth of Oman should be intensely targeted from their that affects the function of that tissue. If we study the early teens, and the dangers of reckless driving should involved neurochemistry, a number of medications are become an important part of the campaign to reduce inju- suggested that can introduce or enhance the chemicals ries and discourage lifestyle conducive to the ‘diseases of that have been altered. With severe injury, the focus of the afiluence.’ In 1998, 23 people per 1,000 vehicles were either rehabilitation may be to enhance the ability to attend to the maimed or killed in traffic accidents.3 Psychosocial studies environment. Of the medications most often employed in should be carried out to delineate behavioural factors lead- rehabilitation, neurostimulants are often mentioned prom- ing to injuries and tease out culture-specific factors respon- inently. These allow the individual to begin or to maximize sible for accidents.36 As youth often occurs with a sense of his ability to focus on the environment and on the process invincibility, those more sober forces of society must assist of rehabilitation. With better focus and longer attention in the prevention of the catastrophic. Traffic surveillance to the learning process the elements of reorganization should be stepped up,backed by stiff and inescapable fines. and teaching of the reorganized tissue can be maximized. Programmes should be evolved to wean away youngsters Theses are not independent issues. One must be attended from the thrill of fast cars to sports or other healthier while the other is ongoing. This illustrates the new, complex forms of catharsis relevant for youth. process of neurorehabilaitation. In spite of best efforts at prevention, the numbers of How practical are the above behavioural and neuro- cases of brain damage will keep rising at least in the short chemical descriptions of the mechanisms of injury and and medium term. During just one year from 1999 to 2000,
recovery? They do suggest that the brain can heal, or be debilitating injuries in Oman increased by 9%.3As we have induced to heal, after injury. The individual then can regain discussed, emerging evidence gives hope that these unfor- self-sufficiency and self worth while he or she is eased into tunate people can indeed be rehabilitated to regain self- independent living. sufficiency. This needs now to be a priority for healthcare If one ponders on the practice and services of reha- planners in Oman who are urged to review and revamp bilitation in Oman, a sense of helplessness would likely the policies and facilities for rehabilitating the victims of take hold, for the field and practice have been largely physical, sensory, cognitive, developmental or emotional
disregarded, and worse, there is no such endeavour on the disabilities that have occurred due to brain injuries. We horizon. Each year, o.3-o.4% of the population of Oman must move not one but two steps ahead of our current is estimated to incur brain injury, principally from road practices. We must encourage the primary prevention of traffic accidents, domestic accidents and falls from date the injuries, and then bring to bear the full weight of our palms.28‘30 Another major cause of brain injuries in Oman medical system to address the issues described above. are the ‘diseases of aflFluence’-diabetes, hypercholester- We can and should see each individual as having a emia, and obesity-that lead to strokes.31’ 32 For victims of weakened neurochemical system that can be strength- these, the protocol has limited itself to reducing mortality. ened, as having rescue mechanisms that can be coerced to accelerate, and once introduced, as having new tissue available Which must be trained towards maximal function. These processes require medical diligence. It is time the healthcare system of Oman rose to the occasion and gave due importance to the rehabilitation of those With brain injury.