|Year : 2019 | Volume
| Issue : 7 | Page : 7--8
Peripheral nerve injuries: From surgical reluctance to rewiring - the road less travelled
B Indira Devi
Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
Dr. B Indira Devi
Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka
|How to cite this article:|
Indira Devi B. Peripheral nerve injuries: From surgical reluctance to rewiring - the road less travelled.Neurol India 2019;67:7-8
|How to cite this URL:|
Indira Devi B. Peripheral nerve injuries: From surgical reluctance to rewiring - the road less travelled. Neurol India [serial online] 2019 [cited 2019 Nov 17 ];67:7-8
Available from: http://www.neurologyindia.com/text.asp?2019/67/7/7/250720
The peripheral nervous system is unique in its intricacy and scope of influence. Peripheral nerve injury and lesions result in considerable disability. It is considered that approximately 5% of all patients who sustain traumatic injury have peripheral nerve or brachial plexus injury. While the incidence may be low, the impact traumatic peripheral nerve injury (TPNI) can have on patients and society is substantial. Loss of function of a limb which is unlikely to regain function in a specified time, with or without surgical intervention, is a catastrophe of the worst kind. It disrupts the social network; there is psychological and emotional crisis as well. These injuries predominantly affect young male patients during their years of peak employment, and a sizable proportion of patients who suffer TPNI may not be able to return to work even after surgery, leading to the lifelong physical and psychological morbidity.
Apart from road traffic accidents, other frequent mechanisms of peripheral nervous system (PNS) injuries have been gunshot injuries, and radiation induced neuropathies due to various head and neck, lung and breast cancers. Pain and motor deficits are the main problems related to radiation induced PNS injury. Iatrogenic peripheral nerve injury can be tricky to identify and can even remain overlooked.
There are several considerations in deciding when to operate, and the surgical intervention may be indicated if there is little evidence of progressive spontaneous recovery of motor and sensory function by three months following the injury., Early surgical exploration is frequently indicated in penetrating or open injuries. The functional recovery varies and depends on the type of nerve, the mode of injury, and electrophysiological findings. While complete recovery is often difficult to obtain, an acceptable level of restored function is possible, and patients should be made to understand realistic therapeutic goals. Furthermore, adequate pain management is very important and aggressive physiotherapy has a positive influence on the prognosis of these patients, both in terms of improving their quality of life and functional recovery, until nerve regeneration has occurred. Progress has been made in the understanding and management of peripheral nerve injuries over the past few decades including refinements in microsurgical techniques, resulting in expanded/extended treatment options for these otherwise devastating injuries.
Brachial plexus injury has been attracting rising attention partly because of increasing survival rates for patients after polytrauma. One potential method of getting better functional outcome in the future may be in utilizing neurotrophic factors to strengthen the reinnervation process. While dealing with the painful consequences of brachial plexus injury, dorsal root entry zone (DREZ) thermocoagulation is a very effective method for the treatment of severe neuropathic pain. The healing process for peripheral nerve surgeries is lengthy, proceeds at 1-2 mm/day but patients should not get discouraged by this reality. One of the main concerns in the management of PNS injury is the ignorance and nihilism shown by the treating physician. The first step in the management of these injuries is to recognize that the injury has occurred. Then, advice should be provided to patients and care-givers regarding the physical therapy to be administered, the range of motion of exercises, the ways to prevent the development of contractures and secondary dislocation (due to muscle atrophy), and the methods to follow for regular assessment to determine any improvement.
Functional impairments caused by nerve injuries can be compensated by three mechanisms: the reinnervation of denervated targets by regeneration of injured axons, the reinnervation by collateral branching of undamaged axons, and the remodeling of nervous system circuitry related to the lost functions.
The role of neural plasticity after nerve injury has been explored more recently. Peripheral nerve injuries induce a concurrent cascade of events at the systemic, cellular and molecular levels, initiated by the trauma to peripheral nerves and progressing throughout plastic changes at the spinal cord, brainstem relay nuclei, thalamus and cerebral cortex. Following nerve repair, cortical plasticity may play a favorable role in rehabilitation by promoting sensory reduction and motor learning, but it can also lead to dysfunctional changes resulting in chronic pain or inferior functional outcomes. In the future, understanding the role of cortical plasticity will be a key contributor to further improvements in motor and sensory outcomes.
In the past decade, research has demonstrated that cortical plasticity is a key factor in determining the prognosis of sensorimotor abilities following nerve injury and repair. Brain imaging studies provide evidence linking functional outcome with brain plasticity. It has been highlighted that peripheral nerve injury, its management, and its successful treatment, cause dynamic changes within the brain's default mode network resting state networks, which include not only the obvious sensorimotor network but also the higher cognitive networks such as the salience network and default mode network, which indicates that brain plasticity and compensatory mechanisms are at work. Resting functional magnetic resonance imaging (fMRI) of the brain and diffusion tensor imaging can predict the cortical changes primarily due to peripheral nerve/brachial plexus injury and the altered connectivity. In children with brachial plexus injury due to birth-related injuries, the diffusion tensor imaging (DTI) and volumetry of corpus callosum has shown extensive volume loss.
Perhaps in the not-so-distant future, resting fMRI and DTI may be able to predict the outcomes following an injury. An important direction for ongoing research is the development of therapeutic strategies that not only help in improving functional recovery but also in diminishing the undesirable consequences of nerve injury.
This supplement of Neurology India has many mini-reviews and commentaries on various surgical aspects and surgically treated lesions of peripheral nerves. The review by Ramachandran and Midha succinctly summarizes the current status of the surgical options. The editorial by Rasulić et al., takes us through a short journey of the current philosophy of surgical management of these lesions.
The important yet rarely addressed issue of dyesthetic pain following injury to peripheral nerves is described in the article by Socolovsky et al. The functional outcome following nerve repair has been comprehensively described by Siqueira et al.
Ethically and medico-legally important issues, such as injection-induced nerve palsies and iatrogenic palsies are addressed in the articles by Warade et al., and Kumar et al. The difficult and often disappointing issues of plexiform neurofibromas in patients with NF1 are discussed by Gorrozo in an interesting article. The use of animal models in peripheral nerve injury research is well explained by Mohanty et al.
Markers for peripheral nerve injuries and possible prognostic factors for outcome can be studied with resting fMRI and DTI.
This supplemental issue attempts to comprehensively cover the relatively lesser-known features related to peripheral nerve etiology. In doing so, it attempts to rejuvenate the enthusiasm of neurorologists, neurosurgeons, neuroradiologists, and neuro-electrophysiologists in dealing with this often-neglected field of neuroscience. Any advancements that emerge out of our concentrated attention in this arena will have far-reaching positive consequences on the management of these unfortunate patients, who are usually in the prime years of their productivity.
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