Magnetic resonance neurography of peripheral nerve following experimental crush injury, and correlation with functional deficit.
OBJECTIVE
In a number of clinical studies magnetic resonance (MR) neurography has been used to examine patients with peripheral nerve damage, but little is understood about the sequence of imaging changes following nerve injuries, and how they correlate with functional deficit. The goal of this study was to further understanding of these changes and their implications.


METHODS
Using the rat sciatic nerve crush model, the sciatic nerve was imaged at intervals over 70 days in 12 rats. Sham-operated contralateral nerves served as controls. A 4.7-tesla MR imager with a custom-made surface coil was used. The T2 maps were calculated from images obtained at four echo times and from regions of interest designated on the nerve at three sites. Walking-track analysis was performed at the same intervals as imaging. Magnetic resonance neurography revealed a mean T2 of normal sciatic nerve of 36 msec (standard deviation [SD] 1.2 msec). Crushed nerves demonstrated a sequence of changes in signal intensity that were maximal at 14 days, with a mean T2 of 64 msec (SD 5.2 msec), then falling to a T2 of 53 msec (SD 3.7 msec). Sham-operated nerves had a short and nonsustained rise in signal at 7 days. Walking-track analysis revealed maximum deficit immediately postinjury, with an improvement in function approaching that of control nerves at 30 days.


CONCLUSIONS
In this study the authors demonstrate that quantitative assessment of nerve signals with MR neurography allows the sequence of events following nerve crush injury to be followed in vivo, and that a return toward a normal signal correlates with functional improvement. Assessment of peripheral nerve injury in patients by using MR neurography has the potential to confirm acute nerve injury as well as to monitor the recovery process.
Cudlip
Simon A
SA
Department of Neurosurgery, Atkinson Morley Neuroscience Centre, London, United Kingdom. simon-c@breathemail.net
Howe
Franklyn A
FA
Griffiths
John R
JR
Bell
B Anthony
BA
D000818:Animals; D004195:Disease Models, Animal; D005684:Gait / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D009409:Nerve Crush / Q000009:adverse effects*; D009410:Nerve Degeneration / Q000209:etiology* / Q000473:pathology* / Q000503:physiopathology; D009416:Nerve Regeneration / Q000502:physiology; D009422:Nervous System Diseases / Q000209:etiology* / Q000473:pathology* / Q000503:physiopathology; D059348:Peripheral Nerve Injuries; D010525:Peripheral Nerves / Q000473:pathology* / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000293:injuries* / Q000473:pathology* / Q000503:physiopathology