Page 14 - Read Online

Ultrasound is already in use for a number of indications and physical examination approach permits formulation
in the evaluation of nerves and is likely to find increasing of a differential diagnosis to guide the neurophysiological
indications in the future. [37‑39] However, further clinical exam and estimate prognosis. Nerve imaging evaluation
and biomedical research is required to further validate its completes the work‑up by visualizing fascicles and
application in preoperative and postoperative monitoring. continuity of the nerve and its surrounding tissue.
Magnetic resonance imaging Clinical and instrumental data should be integrated
MRI is appreciated mainly for its wide overview of the limb to plan adequate treatment and promote functional
with the option of selective volume reconstruction. Direct recovery. High‑resolution nerve imaging, when
nerve visualization by MRI has also been optimized; [40,41] correlated with neurophysiological data, provides the
“MR neurography” combines fat suppression T2‑weighted missing link to clinicians and surgeons, closing the
sequences and diffusion weighting in high magnetic field gap between diagnostic and therapeutic approaches.
gradients (1.5T or higher). The nerve’s signal increases To optimize prognosis, this comprehensive evaluation
significantly following traumatic nerve injury, resulting is mandatory not only during the preoperative stage,
in high contrast of the bright nerve (hyperintense) but also during follow‑up in order to recognize late or
against the surrounding muscle or fat. The increased non‑recovery, thus preventing permanent neurological
nerve signal due to axonal degeneration can be observed disability.
both at the site of the injury and distally, and is the
single most searched MRI sign for localization of nerve REFERENCES
injuries. However, it is not a specific sign, reflecting only
endoneurial or perineural edema and slower axoplasmic 1. Taylor CA, Braza D, Rice JB, Dillingham T. The incidence of peripheral nerve
transport secondary to axonal degeneration. injury in extremity trauma. Am J Phys Med Rehabil 2008;87:381‑5.
2. di Summa PG, Kalbermatten DF, Pralong E, Raffoul W, Kingham PJ,
Diffusion‑weighting imaging has the potential to Terenghi G. Long‑term in vivo regeneration of peripheral nerves through
detect structural anisotropy by determination of the bioengineered nerve grafts. Neuroscience 2011;181:278‑91.
main orientation of the axons within the nerves; 3. Seddon HJ. A classification of nerve injuries. Br Med J 1942;2:237‑9.
4.
Sunderland S. The anatomy and physiology of nerve injury. Muscle Nerve
this method is called diffusion tensor imaging (DTI). 1990;13:771‑84.
From DTI data, a three‑dimensional reconstruction 5. Gupta R, Rummler L, Steward O. Understanding the biology of compressive
of major fascicles can be rendered and is referred to neuropathies. Clin Orthop Relat Res 2005;436:251‑60.
as “tractography”. Tractography provides structural 6. Gupta R, Rowshan K, Chao T, Mozaffar T, Steward O. Chronic nerve
[42]
compression induces local demyelination and remyelination in a rat model
information on the nerves, but has low spatial resolution of carpal tunnel syndrome. Exp Neurol 2004;187:500‑8.
and a low signal‑to‑noise ratio, adding no additional 7. Bernsen HJ, Koetsveld A, Frenken CW, van Norel GJ. Neuropraxia of the
information to neurophysiological data. cervical spinal cord following cervical spinal cord trauma: a report of five
patients. Acta Neurol Belg 2000;100:91‑5.
Many techniques including MRI myelography, MR 8. Lee SK, Wolfe SW. Peripheral nerve injury and repair. J Am Acad Orthop Surg
neurography, and DTI can be combined for additional data, 2000;8:243‑52.
for example in root avulsions in patients with brachial 9. Menorca RM, Fussell TS, Elfar JC. Nerve physiology: mechanisms of injury
and recovery. Hand Clin 2013;29:317‑30.
plexus injuries, but in order for the higher sequences to 10. Koeppen AH. Wallerian degeneration: history and clinical significance.
[43]
be carried out, greater acquisition times are required. J Neurol Sci 2004;220:115‑7.
11. Kleggetveit IP, Jørum E. Large and small fiber dysfunction in peripheral nerve
To overcome current limitations of MRI and enable injuries with or without spontaneous pain. J Pain 2010;11:1305‑10.
investigation of nerves along a limb with faster image 12. Intiso D, Grimaldi G, Russo M, Maruzzi G, Basciani M, Fiore P, Zarrelli M,
acquisition, widespread upgrade to 3T scanners combined Di Rienzo F. Functional outcome and health status of injured patients with
peripheral nerve lesions. Injury 2010;41:540‑3.
with parallel imaging will be required. 13. Pinelli P, Poloni M. Neurology. Principles of Diagnosis and Therapy. 3rd ed.
Future application of new technologies for nerve imaging Rozzano: Casa Editrice Ambrosiana; 2003. p. 75‑87.
such as very high field magnetic fields (9.4T) MRI, 14. Medical Research Council of the UK. Aids to the investigation of peripheral
[44]
nerve injuries. Memorandum No. 45. London: Pendragon House; 1976. p. 6‑7.
or very high frequency ultrasound probes (55 MHz) [45] 15. Aminoff MJ. Electrophysiologic testing for the diagnosis of peripheral nerve
will also increase spatial resolution up to a theoretical injuries. Anesthesiology 2004;100:1298‑303.
histological precision of 30 μm. 16. Robinson LR. Traumatic injury to peripheral nerves. Muscle Nerve
2000;23:863‑73.
At this time, HRU provides the highest spatial resolution 17. Bergquist ER, Hammert WC. Timing and appropriate use of electrodiagnostic
of direct nerve imaging along the limbs, while MRI studies. Hand Clin 2013;29:363‑70.
provides a high contrast delineation of preselected single 18. Kane NM, Oware A. Nerve conduction and electromyography studies.
J Neurol 2012;259:1502‑8.
segments of the body. Both can assist in the resolution 19. Campbell WW. Evaluation and management of peripheral nerve injury.
of pitfalls in injury localization, which may arise if only Clin Neurophysiol 2008;119:1951‑65.
certain proximal nerve fascicles are injured, and others 20. Gutmann L, Pawar GV. An approach to electrodiagnosis of peripheral
neuropathies. Semin Neurol 2005;25:160‑7.
are spared, simulating a distal neuropathy. 21. Fisher MA. Electrophysiology of radiculopathies. Clin Neurophysiol
2002;113:317‑35.
CONCLUSION 22. Perry JD. Electrodiagnosis in musculo‑skeletal disease. Best Pract Res Clin
Rheumatol 2005;19:453‑66.
23. Restuccia D, Valeriani M, Di Lazzaro V, Tonali P, Mauguière F. Somatosensory
Evaluation of peripheral nerve injuries remains a challenge evoked potentials after multisegmental upper limb stimulation in diagnosis of
for both clinicians and surgeons. A comprehensive clinical cervical spondylotic myelopathy. J Neurol Neurosurg Psychiatry 1994;57:301‑8.

154 Plast Aesthet Res || Vol 2 || Issue 4 || Jul 15, 2015