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| COMMENTARY |
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| Year : 2017 | Volume
: 65
| Issue : 3 | Page : 556-557 |
Peripheral nerve injuries – A call for better evaluation and preventive measures
Arun Kumar Singh
Department of Plastic Surgery, King George Medical University, Lucknow, Uttar Pradesh, India
| Date of Web Publication | 9-May-2017 |
Correspondence Address:
Arun Kumar Singh
President, Indian Society for Peripheral Nerve Surgery, Postgraduate Department of Plastic Surgery, King George Medical University, Lucknow, Uttar Pradesh
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/neuroindia.NI_347_17
How to cite this article:
Singh AK. Peripheral nerve injuries – A call for better evaluation and preventive measures. Neurol India 2017;65:556-7 |
Peripheral nerve injuries (PNIs) are an important cause of disability in the general population, of which many of the members belong to the young and productive age group. Data is sparse on the incidence of PNIs and not many evaluations have been performed systematically. In possibly the first systematic evaluation, Mitchell et al., studied such injuries at the time of American Civil War and prepared their excellent compilation.[1] Analysis of a decade-long data revealed a prevalence rate of PNIs at 2.8% in patients suffering from trauma.[2]
It may be noted that an exact estimation of PNIs is fraught with several overlaps and biases. Patients with trauma may have multiple injuries masking the PNIs either because of encephalopathy or indifference, or involving the nerve distribution at different points of the neuraxis making the evaluation complicated.
Kouyoumdjian et al., have attempted an evaluation of patients with PNIs referred to their Neuromuscular Investigation Laboratory for an electrodiagnostic evaluation.[3] In this long-period (26 years) retrospective series, data of 1124 consecutive patients with PNIs (1418) were subjected to analysis. Approximately half of all PNIs occurred after vehicular accidents while approximately one-fourth of all patients suffered from penetrating trauma. Most people in this series were in the early third decade with almost three-fourth of them being males. Individually, or in combination with other peripheral nerves, ulnar nerve was the most commonly involved nerve followed by brachial plexus injury. Understandably, upper limb nerve involvement outnumbered involvement of nerves of the lower limbs.
Seddon [4] and Sunderland [5] classification schemes are commonly used to grade the degree of nerve injury. The Seddon's classification is simple and grades the injury into neurapraxia, axonotmesis, and neurotmesis; while, the Sunderland classification grades the injury into five types and is technically superior. First degree and fifth degree injury of Sunderland correspond to neurapraxia and neurotmesis, respectively. On the other hand, second through fourth degree can be equated with axonotmesis in increasing order of severity of damage to nerves. MR neurography based classification scheme has also been proposed with the advent of high resolution imaging systems.[6]
Electrodiagnostic studies are indispensable in patients with PNIs. Not only do they help in assessing the degree of injury to the nerve, they are also helpful in determining the age of injury and subsequent prognostication. Interventions, thus, can be performed with more confidence in each patient. Nerve conduction studies (NCS) and electromyography (EMG) have their independent advantages and are best performed as complementary evaluations. For example, in a patient suspected of having a root avulsion, with or without brachial plexus injury, it may be impossible to localize the lesion. Late response estimation might be very helpful in patients with proximal lesions where the distal nerve normalcy may be deceptive. Similarly, patients may resume normal motor functioning but may still have a delayed conduction because of the remyelination characteristics.
When to order or perform the electrodiagnostic study after a PNI is extremely important. In the first week post-injury, both NCS and EMG may be normal barring the voluntary estimation of muscle potentials in neurotmesis. NCS in the second week and beyond shows a delay in conduction and a drop in the compound muscle action potentials (CMAPs). On EMG, assessment of recruitment pattern may be very deceptive in any given phase. The recruitment pattern is usually decreased; however, appearance of fibrillation potentials and positive sharp waves suggest a denervation pattern which is usually seen after 3 weeks of injury. Long duration large amplitude potentials (fasciculations) suggest a reinnervation pattern appearing sometime 2-3 months after the injury. It has been shown that single fiber EMG can demonstrate reinnervation in patients with PNI in as early as 3 weeks.[7] Thus, as a rule of thumb, electrodiagnostic studies are best performed around 3 weeks after the injury to get maximum amount of information.[8] It goes without saying that performing a repeat study at subsequent follow-up visits provides a better insight into the course of nerve injury.
Surgical planning after PNIs is a difficult job as it requires a precise time-frame management along with assessment of the degree of recovery desired or possible. Since recovery depends on a lot of factors ranging from the type of injury (sharp versus blunt, clean versus contaminated, etc.) to the site of lesion (proximal versus distal, single versus multiple, etc.), the planning needs to be customized.
Everything said and done, prevention is better than cure. Since most PNIs occur secondary to vehicular accidents involving the most productive age-group of the society, educational activities to disseminate the aspect of safe driving must be undertaken on a larger scale besides better implantation of the road traffic rules and regulations.
| » References | |  |
| 1. | Mitchell SW, Morehouse GR, Keen WW. Gunshot wounds and other injuries of nerves. 1864. Clin Orthop Relat Res 2007 May; 458:35-9.  |
| 2. | Noble J, Munro CA, Prasad VS, Midha R. Analysis of upper and lower extremity peripheral nerve injuries in a population of patients with multiple injuries. J Trauma 1998;45:116-22. [ PUBMED] |
| 3. | Kouyoumdjian JA, Graça CR, Ferreira VFM. Peripheral nerve injuries: A retrospective survey of 1124 cases. |
| 4. | Seddon H. Three types of nerve injury. Brain 1943;66:237-88. |
| 5. | Sunderland S. A classification of peripheral nerve injuries producing loss of function. Brain 1951;74:491-516. [ PUBMED] |
| 6. | Chhabra A, Ahlawat S, Belzberg A, Andreseik G. Peripheral nerve injury grading simplified on MR neurography: As referenced to Seddon and Sunderland classifications. Indian J Radiol Imaging 2014;24:217-24. [ PUBMED] [Full text] |
| 7. | Massey JM, Sanders DB. Single-fiber EMG demonstrates reinnervation dynamics after nerve injury. Neurology 1991;41:1150-1. [ PUBMED] |
| 8. | Campbell WW. Evaluation and management of peripheral nerve injury. Clin Neurophysiol 2008;119:1951-65. [ PUBMED] |
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