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Sciatic nerve injury related to hip replacement surgery: imaging detection by MR neurography despite susceptibility artifacts.

Wolf M, Bäumer P, Pedro M, Dombert T, Staub F, Heiland S, Bendszus M, Pham M - PLoS ONE (2014)

Bottom Line: Especially in the presence of metallic implants, commonly applied diagnostic imaging tests generally fail to adequately visualize nervous tissue.MRI has been deemed problematic due to implant-related artifacts after HRS.We were able to determine the localization and fascicular distribution of the sciatic nerve lesion in all 9 patients, which clearly showed on imaging predominant involvement of the peroneal more than the tibial division of the sciatic nerve.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroradiology, University of Heidelberg, Heidelberg, Germany.

ABSTRACT
Sciatic nerve palsy related to hip replacement surgery (HRS) is among the most common causes of sciatic neuropathies. The sciatic nerve may be injured by various different periprocedural mechanisms. The precise localization and extension of the nerve lesion, the determination of nerve continuity, lesion severity, and fascicular lesion distribution are essential for assessing the potential of spontaneous recovery and thereby avoiding delayed or inappropriate therapy. Adequate therapy is in many cases limited to conservative management, but in certain cases early surgical exploration and release of the nerve is indicated. Nerve-conduction-studies and electromyography are essential in the diagnosis of nerve injuries. In postsurgical nerve injuries, additional diagnostic imaging is important as well, in particular to detect or rule out direct mechanical compromise. Especially in the presence of metallic implants, commonly applied diagnostic imaging tests generally fail to adequately visualize nervous tissue. MRI has been deemed problematic due to implant-related artifacts after HRS. In this study, we describe for the first time the spectrum of imaging findings of Magnetic Resonance neurography (MRN) employing pulse sequences relatively insensitive to susceptibility artifacts (susceptibility insensitive MRN, siMRN) in a series of 9 patients with HRS procedure related sciatic nerve palsy. We were able to determine the localization and fascicular distribution of the sciatic nerve lesion in all 9 patients, which clearly showed on imaging predominant involvement of the peroneal more than the tibial division of the sciatic nerve. In 2 patients siMRN revealed direct mechanical compromise of the nerve by surgical material, and in one of these cases indication for surgical release of the sciatic nerve was based on siMRN. Thus, in selected cases of HRS related neuropathies, especially when surgical exploration of the nerve is considered, siMRN, with its potential to largely overcome implant related artifacts, is a useful diagnostic addition to nerve-conduction-studies and electromyography.

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ROI-based measurement of T2-signal intensity of muscle, peroneal and tibial division of the sciatic nerve.siMR neurographic T2-weighted images with fat-saturation (a, b, c). Exemplary ROI-based analysis of signal intensities of the peroneal and tibial portion of the sciatic nerve, the normal appearing musculature, and background noise in patient 5 (a), patient 1 (b) and a healthy control (c). In (a), a distinctive T2-signal increase of the peroneal and tibial nerve in patient 5, and in (b) a T2-signal increase of peroneal division of the sciatic nerve in patient 1 are shown. In the healthy control no pathological nerve signal increase is present (c). In (d) the corresponding SR of the peroneal and tibial portion of the sciatic nerve are shown. In the healthy control, and in the normal appearing tibial portion of the sciatic nerve in patient 1 SR are below 1.7. A SR above 1.7 indicates a lesion of the peroneal portion of the sciatic nerve in patient 1, and in the peroneal and tibial portion of the sciatic nerve in patient 2 (d). Abbreviations: p: peroneal portion of the sciatic nerve or peroneal nerve; SR: nerve-to-muscle T2- signal intensity ratio; t: tibial portion of the sciatic nerve or tibial nerve.
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pone-0089154-g001: ROI-based measurement of T2-signal intensity of muscle, peroneal and tibial division of the sciatic nerve.siMR neurographic T2-weighted images with fat-saturation (a, b, c). Exemplary ROI-based analysis of signal intensities of the peroneal and tibial portion of the sciatic nerve, the normal appearing musculature, and background noise in patient 5 (a), patient 1 (b) and a healthy control (c). In (a), a distinctive T2-signal increase of the peroneal and tibial nerve in patient 5, and in (b) a T2-signal increase of peroneal division of the sciatic nerve in patient 1 are shown. In the healthy control no pathological nerve signal increase is present (c). In (d) the corresponding SR of the peroneal and tibial portion of the sciatic nerve are shown. In the healthy control, and in the normal appearing tibial portion of the sciatic nerve in patient 1 SR are below 1.7. A SR above 1.7 indicates a lesion of the peroneal portion of the sciatic nerve in patient 1, and in the peroneal and tibial portion of the sciatic nerve in patient 2 (d). Abbreviations: p: peroneal portion of the sciatic nerve or peroneal nerve; SR: nerve-to-muscle T2- signal intensity ratio; t: tibial portion of the sciatic nerve or tibial nerve.

Mentions: The evaluation of MRN was performed in consensus by two neuroradiologists (MW, MP) with more than 4 and 7 years, respectively, of training in MRN. Both raters were unblinded because evidence of any HRS implant was inherent to the evaluated images. The sciatic nerve was evaluated for continuity, alterations in caliber and T2-signal intensity within the tibial and peroneal division. The denervation pattern of proximal and distal target muscles of the sciatic nerve at thigh and calf level was analysed by evaluating increased muscular T2- signal. Using the OsiriX Imaging software [18], a Region of Interest (ROI)- based analysis of the T2- signal intensity of the tibial and peroneal division of the sciatic nerve was performed (Figure 1a, b, c). Nerve-to-muscle signal intensity ratios, abbreviated SR, were determined, to objectify the T2-signal of the nerves. The signal intensity of the nerve was related to the signal intensity of normal appearing musculature not in the distribution of the sciatic nerve, i.e. muscles not innervated by the sciatic nerve (Figure 1d).


Sciatic nerve injury related to hip replacement surgery: imaging detection by MR neurography despite susceptibility artifacts.

Wolf M, Bäumer P, Pedro M, Dombert T, Staub F, Heiland S, Bendszus M, Pham M - PLoS ONE (2014)

ROI-based measurement of T2-signal intensity of muscle, peroneal and tibial division of the sciatic nerve.siMR neurographic T2-weighted images with fat-saturation (a, b, c). Exemplary ROI-based analysis of signal intensities of the peroneal and tibial portion of the sciatic nerve, the normal appearing musculature, and background noise in patient 5 (a), patient 1 (b) and a healthy control (c). In (a), a distinctive T2-signal increase of the peroneal and tibial nerve in patient 5, and in (b) a T2-signal increase of peroneal division of the sciatic nerve in patient 1 are shown. In the healthy control no pathological nerve signal increase is present (c). In (d) the corresponding SR of the peroneal and tibial portion of the sciatic nerve are shown. In the healthy control, and in the normal appearing tibial portion of the sciatic nerve in patient 1 SR are below 1.7. A SR above 1.7 indicates a lesion of the peroneal portion of the sciatic nerve in patient 1, and in the peroneal and tibial portion of the sciatic nerve in patient 2 (d). Abbreviations: p: peroneal portion of the sciatic nerve or peroneal nerve; SR: nerve-to-muscle T2- signal intensity ratio; t: tibial portion of the sciatic nerve or tibial nerve.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3928432&req=5

pone-0089154-g001: ROI-based measurement of T2-signal intensity of muscle, peroneal and tibial division of the sciatic nerve.siMR neurographic T2-weighted images with fat-saturation (a, b, c). Exemplary ROI-based analysis of signal intensities of the peroneal and tibial portion of the sciatic nerve, the normal appearing musculature, and background noise in patient 5 (a), patient 1 (b) and a healthy control (c). In (a), a distinctive T2-signal increase of the peroneal and tibial nerve in patient 5, and in (b) a T2-signal increase of peroneal division of the sciatic nerve in patient 1 are shown. In the healthy control no pathological nerve signal increase is present (c). In (d) the corresponding SR of the peroneal and tibial portion of the sciatic nerve are shown. In the healthy control, and in the normal appearing tibial portion of the sciatic nerve in patient 1 SR are below 1.7. A SR above 1.7 indicates a lesion of the peroneal portion of the sciatic nerve in patient 1, and in the peroneal and tibial portion of the sciatic nerve in patient 2 (d). Abbreviations: p: peroneal portion of the sciatic nerve or peroneal nerve; SR: nerve-to-muscle T2- signal intensity ratio; t: tibial portion of the sciatic nerve or tibial nerve.
Mentions: The evaluation of MRN was performed in consensus by two neuroradiologists (MW, MP) with more than 4 and 7 years, respectively, of training in MRN. Both raters were unblinded because evidence of any HRS implant was inherent to the evaluated images. The sciatic nerve was evaluated for continuity, alterations in caliber and T2-signal intensity within the tibial and peroneal division. The denervation pattern of proximal and distal target muscles of the sciatic nerve at thigh and calf level was analysed by evaluating increased muscular T2- signal. Using the OsiriX Imaging software [18], a Region of Interest (ROI)- based analysis of the T2- signal intensity of the tibial and peroneal division of the sciatic nerve was performed (Figure 1a, b, c). Nerve-to-muscle signal intensity ratios, abbreviated SR, were determined, to objectify the T2-signal of the nerves. The signal intensity of the nerve was related to the signal intensity of normal appearing musculature not in the distribution of the sciatic nerve, i.e. muscles not innervated by the sciatic nerve (Figure 1d).

Bottom Line: Especially in the presence of metallic implants, commonly applied diagnostic imaging tests generally fail to adequately visualize nervous tissue.MRI has been deemed problematic due to implant-related artifacts after HRS.We were able to determine the localization and fascicular distribution of the sciatic nerve lesion in all 9 patients, which clearly showed on imaging predominant involvement of the peroneal more than the tibial division of the sciatic nerve.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroradiology, University of Heidelberg, Heidelberg, Germany.

ABSTRACT
Sciatic nerve palsy related to hip replacement surgery (HRS) is among the most common causes of sciatic neuropathies. The sciatic nerve may be injured by various different periprocedural mechanisms. The precise localization and extension of the nerve lesion, the determination of nerve continuity, lesion severity, and fascicular lesion distribution are essential for assessing the potential of spontaneous recovery and thereby avoiding delayed or inappropriate therapy. Adequate therapy is in many cases limited to conservative management, but in certain cases early surgical exploration and release of the nerve is indicated. Nerve-conduction-studies and electromyography are essential in the diagnosis of nerve injuries. In postsurgical nerve injuries, additional diagnostic imaging is important as well, in particular to detect or rule out direct mechanical compromise. Especially in the presence of metallic implants, commonly applied diagnostic imaging tests generally fail to adequately visualize nervous tissue. MRI has been deemed problematic due to implant-related artifacts after HRS. In this study, we describe for the first time the spectrum of imaging findings of Magnetic Resonance neurography (MRN) employing pulse sequences relatively insensitive to susceptibility artifacts (susceptibility insensitive MRN, siMRN) in a series of 9 patients with HRS procedure related sciatic nerve palsy. We were able to determine the localization and fascicular distribution of the sciatic nerve lesion in all 9 patients, which clearly showed on imaging predominant involvement of the peroneal more than the tibial division of the sciatic nerve. In 2 patients siMRN revealed direct mechanical compromise of the nerve by surgical material, and in one of these cases indication for surgical release of the sciatic nerve was based on siMRN. Thus, in selected cases of HRS related neuropathies, especially when surgical exploration of the nerve is considered, siMRN, with its potential to largely overcome implant related artifacts, is a useful diagnostic addition to nerve-conduction-studies and electromyography.

Show MeSH
Related in: MedlinePlus