4/14/2017. Disclosures. Peripheral Nerve Imaging: Lumbosacral plexus MRI. No relevant financial relationship to disclose

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1 Peripheral Nerve Imaging: Lumbosacral plexus MRI Disclosures No relevant financial relationship to disclose Sarah E. Stilwill M.D.- MSK Radiology Division, University of Utah Avneesh Chhabra M.D. Chief of MSK Radiology Division, UT Southwestern R. Kent Sanders M.D. MSK Radiology, North Canyon Medical Center Idaho Megan K Mills M.D. - MSK Radiology Division, University of Utah Importance of imaging the LS Plexus Importance of imaging the LS Plexus Often clinically difficult to tease out spine related abnormalities vs LS plexus pathology Often clinically difficult to tease out spine related abnormalities vs LS plexus pathology MR Neurography has dramatically improved ways of accurately diagnosing exact location, type, extent and cause of the peripheral plexopathy Chhabra et all. MRN: Past, present and future. AJR 2011; 197: Sag T2 Chhabra et all. MRN: Past, present and future. AJR 2011; 197: What is the Lumbosacral plexus? What is the Lumbosacral plexus? Coalescence of the ventral rami of the lumbar and sacral spinal nerve roots forming the lumbrosacral trunk Wikipedia 1

2 What is the Lumbosacral plexus? Coalescence of the ventral rami of the lumbar and sacral spinal nerve roots forming the lumbrosacral trunk Specifically L4-S3 nerves --> LS Plexus What is the Lumbosacral plexus? Coalescence of the ventral rami of the lumbar and sacral spinal nerve roots forming the lumbrosacral trunk Specifically L4-S3 nerves --> LS Plexus Provides motor and sensory innervation to most structures of the pelvis and lower extremities R Femoral Neuropathy Soltados et al. High Resolution 3T MRN of the LS Plexus. Radiographics 2013; What is the Lumbosacral plexus? Educational Objectives Coalescence of the ventral rami of the lumbar and sacral spinal nerve roots forming the lumbrosacral trunk Specifically L4-S3 nerves --> LS Plexus Provides motor and sensory innervation to most structures of the pelvis and lower extremities Very susceptible to traumatic, inflammatory, metabolic, and neoplastic processes Amyloid Review our institutions imaging protocol Cor T1 FS PG Dr. Chhabra Chhabra SSR 2017 Educational Objectives Review our institutions imaging protocol Review normal nerve anatomy Educational Objectives Review our institutions imaging protocol Review normal nerve anatomy Recognize key imaging findings of LS plexus pathology Chhabra SSR 2017 Chhabra SSR

3 Combination of 2D and 3D techniques 1.5T and 3T 3T better SNR, can get thinner slices and MIP recons Combination of 2D and 3D techniques 1.5T and 3T 3T better SNR, can get thinner slices and MIP recons Axial T1 and T2 FS/ SPAIR Cor T1 and / SPAIR Combination of 2D and 3D techniques 1.5T and 3T 3T better SNR, can get thinner slices and MIP recons Axial T1 and T2 FS/ SPAIR Cor T1 and / SPAIR Contrast for tumors and infection >>> inflammation Combination of 2D and 3D techniques 1.5T and 3T 3T better SNR, can get thinner slices and MIP recons Axial T1 and T2 FS/ SPAIR Cor T1 and / SPAIR Contrast for tumors and infection >>> inflammation Future: DWI/DTI sequences Cor T 1 FS PC Dr. Chhabra Zhao L et al. Diffusion-Weighted MR Neurography of Extremity Nerves With Unidirectional Motion-Probing Gradients at 3 T: Feasibility Study. AJR, 2013 vol 200, No 5. Combination of 2D and 3D techniques 1.5T and 3T 3T better SNR, can get thinner slices and MIP recons Axial T1 and T2 FS/ SPAIR Cor T1 and / SPAIR Contrast for tumors and infection >>> inflammation Future: DWI/DTI sequences PSIF??? Selective nerve imaging 2D or 3D Coronal STIR - useful for LS plexus nerve size and signal with excellent contrast resolution for depicting pathology. Great for internal nerve architecture. 3D SPACE 3

4 (Axial and Coronal) T1 non FS-key sequences for peri-neural and intermuscular fat plane evaluation, chronic fatty muscle atrophy, bone marrow signal and Met-hgb blood products (Axial and Coronal) T1 non FS-key sequences for peri-neural and intermuscular fat plane evaluation, chronic fatty muscle atrophy, bone marrow signal and Met-hgb blood products Axial T2 FS +/- SPAIR -2D images provide detailed fascicular depiction of the lumbrosacral plexus nerve roots and their peripheral branches, size, course and caliber - Mainstay sequence Axial T2 FS +/- SPAIR -2D images provide detailed fascicular depiction of the lumbrosacral plexus nerve roots and their peripheral branches, size, course and caliber - Mainstay sequence MR Evaluation of Peripheral Nerves Normal MR Evaluation of Peripheral Nerves Abnormal Normal nerves intermediate signal on T1 WI and intermed/slightly inc signal on T2WI Similar size to adjacent arteries / vessels, with a decrease in size distally Normal fascicular pattern on both T2 >> T1 Smooth, continuous morphology, + preserved perineural fat No enhancement Abnormal nerves are hyperintense on T2 WI Focal or diffusely enlarged, larger than adjacent arteries Abnormal fascicular pattern--> enlarged and/or disrupted fascicles Irregular, focal or diffuse deviations, +/- nerve discontinuty, + effacement of peri-neural fat planes + Enhancement in tumors and infections 2/2 disruption of BBB 4

5 MR Evaluation of Peripheral Nerves Abnormal Proximal Cords Abnormal nerves are hyperintense on T2 WI Focal or diffusely enlarged, larger than adjacent arteries Abnormal fascicular pattern--> enlarged and/or disrupted fascicles Irregular, focal or diffuse deviations, +/- nerve discontinuty, + effacement of peri-neural fat planes + Enhancement in tumors and infections 2/2 disruption of BBB SA Lateral SAG T2 FS Posterior Medial Lumbosacral Plexus: Anatomy Overview LS Trunk- L4-S3 Nerves to know: Lateral femoral cutaneous (L2-3) Obturator (L2-4) mostly L3 Femoral (L2-4) mostly L4 Sciatic Nerve (L4-S3) Common Peroneal (L4-S2) mostly L5 Tibial (L4-S3) mostly S1 Pudendal (S2-4) plexus really the medial inferior sacral plex. at sciatic notch. Proximal sacral nerves larger than distal. Lumbosacral Plexus: L3-S1 nerve course Lumbosacral Plexus: L3-S1 nerve course L4 L5 Ax T1 at L4/L5 Ax T1 at L5/S1 Lumbosacral Plexus: L3-S1 nerve course Lumbosacral Plexus: L3-S1 nerve course Ax Ax T1 T1 at at L5/S1 Sacrum- L5 along sacral alae Ax T1 sciatic notch 5

6 Lumbosacral Plexus: L3-S1 nerve course Lumbosacral Plexus: L3-S1 nerve course Obturator nerve ( L2-L4) --> innervates external obturator, adductor muscles Femoral nerve ( L2-L4) --> innervates iliacus, pectineus, prox anterior thigh muscles Sciatic nerve ( L4-S1) --> via peroneal and tibial nerve components inervates leg muscles Ax T1 sciatic notch MR Case Based Review of LS Plexus Pathology Intrinsic neuropathy Acute vs chronic Focal vs Diffuse Tumor /Tumor like lesions NF/Neurofibromatosis Perineuroma Lymphoma Inflammatory Radiation plexitis/ plexopathy CIDP Trauma Intrinsic Neuropathies: Focal Acute 36 YOF awoke with sciatica following colon surgery Intrinsic Neuropathies: Focal Acute Intrinsic Neuropathies: Focal Acute 36 YOF awoke with sciatica following colon surgery 36 YOF awoke with sciatica following colon surgery Edematous sciatic nerve + Perineural edema No denervation change yet = Acute 6

7 Intrinsic Neuropathies: Focal Acute 36 YOF awoke with sciatica following colon surgery Intrinsic Neuropathies: Acute on Chronic 26 yo F with Myesenthia Gravis and L4/L5 radiculopathy on exam Cor T1 FS PG Edematous sciatic nerve + Perineural edema No denervation change yet = Acute + Enhancement 2/2 stretch injury Intrinsic Neuropathies: Acute on Chronic 26 yo F with Myesenthia Gravis and L4/L5 radiculopathy on exam Intrinsic Neuropathies: Acute on Chronic 26 yo F with Myesenthia Gravis and L4/L5 radiculopathy on exam Subtle asymmetrically enlarged and edematous L4 lateral branch and L5 nerves at L5/S1 Acute denervation edema in gluteus minimus muscle with enlargement of the coursing gluteal nerves Enlarged and edematous sciatic nerve Intrinsic Neuropathies: Acute on Chronic 26 yo F with Myesenthia Gravis and L4/L5 radiculopathy on exam Intrinsic Neuropathies: Acute Femoral Gluteus minimus and glut medius muscle innervation --> Superior gluteal nerve (NR L4-S1) 37 yo M found down + bilateral femoral neuropathy and rhabdomyolysis 7

8 Intrinsic Neuropathies: Acute Femoral Intrinsic Neuropathies: Acute Femoral 37 yo M found down + bilateral femoral neuropathy and rhabdomyolysis 37 yo M found down + bilateral femoral neuropathy and rhabdomyolysis Intrinsic Neuropathies: Acute Femoral Intrinsic Neuropathies: Acute Femoral 37 yo M found down + bilateral femoral neuropathy and rhabdomyolysis Iliopsoas myonecrosis 37 yo M found down + bilateral femoral neuropathy and rhabdomyolysis Intrinsic Neuropathies: Acute Femoral Intrinsic Neuropathies: Acute Obturator 55 yo F s/p anterior lumbar fusion with post op adductor weakness 37 yo M found down + bilateral femoral neuropathy and rhabdomyolysis Denervation muscle edema Cor T1 8

9 Intrinsic Neuropathies: Acute Obturator 55 yo F s/p anterior lumbar fusion with post op adductor weakness Intrinsic Neuropathies: Acute Obturator 55 yo F s/p anterior lumbar fusion with post op adductor weakness Cor T1 Cor T1 Denervation edema OE Top 3 Take Home Points: Know the patient s clinical distribution of symptoms Understand the normal course and configuration of the implicated nerves Know the downstream muscle innervation patterns to assist with upstream localization of plexopathy MR Case Based Review of LS Plexus Pathology Intrinsic neuropathy Acute vs chronic Focal vs Diffuse Tumor /Tumor like lesions NF/Neurofibromatosis Perineuroma Lymphoma Inflammatory Radiation plexitis/ plexopathy CIDP Trauma Tumor and Tumor- like Lesions Malignant plexopathy is commonly due to infiltration/ invasion from primary pelvic tumor Prostate cancer, colorectal cancer Tumor and Tumor- like Lesions Malignant plexopathy is commonly due to infiltration/ invasion from primary pelvic tumor Prostate cancer, colorectal cancer Lymphoma, leukemia, melanoma, breast and lung cancer are the most common extra-pelvic primary malignancies to directly invade the LS plexus Mets to the nerves are very rare 9

10 Tumor and Tumor- like Lesions Tumor and Tumor-like Lesions: Neurofibromatosis Malignant plexopathy is commonly due to infiltration/ invasion from primary pelvic tumor Prostate cancer, colorectal cancer Lymphoma, leukemia, melanoma, breast and lung cancer are the most common extra-pelvic primary malignancies to directly invade the LS plexus Mets to the nerves are very rare Intrinsic tumors of the lumbosacral plexus include: PNST/ NF, perineuroma, neurolymphoma 50 yo F NF-1 MIP 45 yo M with NF-1 MR images show manifestations of neurofibromatosis, with more extensive plexiform disease on the left. Tumor and Tumor-like Lesions: Neurofibromatosis Companion tumor cases: Neurofibromatosis and MPNST 50 yo F NF-1 45 yo M with NF-1 35 yo F with NF-1 and diffuse involvement of the BP 40 yo F with NF-1 and MPNST Coronal T1WI C+ FS StatDx MIP Neurofibromas are the most common benign neural tumor to involve the BP and LSP 1/3 of these tumors occur in patients with NF-1; 2/3 s of cases are sporadic Plexiform neurofibromas are pathopneumonic for NF-1, with increased risk of malignant txf Wittenburg KH. Radiographics, Tumor and Tumor like lesions: Perineuroma 35 yo F with sciatica Tumor and Tumor like lesions: Lymphoma 45 yo F with progressive right lower extremity weakness and pain with known Non-Hodgkin's Lymphoma Dr. Chhabra Dr. Chhabra Cor T1 FS Post contrast Cor T1 FS Post contrast Diffuse nerve enlargement with Iso T1, hyper on T2, avid homogeneous enhancement, with prominent enlarged fasicular pattern Fat planes preserved, no muscle invasion Rodrigues JF et al. Acta Neuropathol Mar; 123 (3): Wadhwa V et al.skeletal Radiology, 2012, V 41, I7, Loss of fascicular architecture Difffuse nerve enlargement Solid tumoral enhancement 10

11 MR Case Based Review of LS Plexus Pathology Intrinsic neuropathy Acute vs chronic Focal vs Diffuse Tumor /Tumor like lesions NF/Neurofibromatosis Perineuroma Lymphoma Inflammatory Radiation plexitis/ plexopathy CIDP Trauma Inflammatory: Radiation induced plexopathy LS plexus often included in the therapeutic FOV for XRT of prostate cancer, colorectal cancer and gynecological tumors Inflammatory: Radiation induced plexopathy LS plexus often included in therapeutic FOV for XRT of prostate cancer, colorectal cancer and gynecological tumors Neuropathy related to radiation therapy tends to occur between 5 and 30 months after treatment, with a peak incidence between 10 and 20 month Inflammatory: Radiation induced plexopathy LS plexus often included in therapeutic FOV for XRT of prostate cancer, colorectal cancer and gynecological tumors Neuropathy related to radiation therapy tends to occur between 5 and 30 months after treatment, with a peak incidence between 10 and 20 month Clinically evident damage is most likely to occur when at least 6000 cgy is administered Inflammatory: Radiation induced plexopathy 59 yo M with progrssive RLE pain and weakness s/p XRT for PCa nodal mets Inflammatory: CIDP AX T1 FS Post contrast Chronic Inflammatory Demyelinating Polyneuropathy Acquired immune-mediated inflammatory disorder of the PNS Progressive symmetrical weakness in both proximal and distal muscles, with sensory deficits and areflexia Patients present with radicular pain, which can be progressive and intermittent Rare; chronic counterpart of GBS Mild to moderate diffuse nerve enlargement within XRT field Variable T2 signal intensity, hypointensity on T1, + perineural edema Mild diffuse enhancement and / or thin tram track pattern of enhancement +/- peripheral soft-tissue scarring in the chronic phase + Downstream denervation changes Crush et al, Radiographics

12 Inflammation: CIDP 26 YO F with progressive neck and back pain progressed over a 2 month period Inflammation: CIDP vs Charcot Marie Tooth (CMT) 26 YO F with CIDP 30 yo F known hx of CMT Bilateral, symmetrical mild diffuse nerve enlargement with abnormal T2/STIR hyperintensity in the classic symmetric form of CIDP DDx: Charcot Marie Tooth and Neurofibromatosis Wadhwa V et al.skeletal Radiology, 2012, V 41, I7, Charcot Marie Tooth: Inherited demyelinating polyneuropathy characterized by distal muscle weakness and atrophy, impaired sensation, and diminished deep tendon reflexes Affected nerves are hyperintense on T2/STIR, diffusely enlarged Thawait et al. AJNR Am J Neuroradiol 32: Sep Top 3 take home points Clinical history is key to diagnosis Be cautious when interpreting the LS plexus post treatment setting as radiation plexitis and recurrent tumor can look the same! Symmetry is your friend Ensure your FOV covers both sides MR Case Based Review of LS Plexus Pathology Intrinsic neuropathy Acute vs chronic Focal vs Diffuse Tumor /Tumor like lesions NF/Neurofibromatosis Perineuroma Lymphoma Inflammatory Radiation plexitis/ plexopathy CIDP Trauma Traumatic Injuries to LS Plexus Traumatic Injuries to LS Plexus Commonly occur in conjunction with bony injuries Acetabulum and pelvic ring Sacral plexus most frequently injured Commonly occur in conjunction with bony injuries Acetabulum and pelvic ring Sacral plexus most frequently injured Post-operative plexus injuries can occur due to XS compressive / traction during the procedure and / or development of a psoas hematoma 12

13 Cranial Caudal 4/14/2017 Traumatic Injuries: Sacral plexus stretch injury 70 yo F with Sacral insufficiency fracture Asymmetric left sided S1 and S2 nerve edema with focal kinking Lateral L3 spinal root L2 spinal root 70 yo M s/p lateral spine surgery w/ acute lumbar plexopathy Femoral nerve Dr. Chhabra L4-5 interspace L3-4 interspace Medial Dr. Mark Mahan Summary Understanding the complex anatomy of the LS plexus is key to interpretation on MRI Recognizing direct and indirect imaging findings of LS plexus pathology aids in early diagnosis and early intervention Don t forget about the soft tissues! Clinical history is key Thank you! Sarah Stilwill MD Sarah.stilwill@hsc.utah.edu References Kim, Y. H., Lee, P. B., Lee, C. J., Lee, S. C., Kim, Y. C., & Huh, J. (2008). Dermatome variation of lumbosacral nerve roots in patients with transitional lumbosacral vertebrae. Anesthesia and Analgesia, 106(4), table of contents. Seyfert, S. (1997). Dermatome variations in patients with transitional vertebrae. Journal of Neurology, Neurosurgery, and Psychiatry, 63(6), Kim, Su-Fin et al.( 2011). MR imaging mapping of skeletal muscle denervation in entrapment and compressive neuropathies. Radiographics, 31: Filler, A. (2009) Diagnosis and treatment of pudendal nerve entrapment syndrome subtypes: imaging, injections, and minimal access surgery. Neurosurgery Focus, 26(2),1-14 Nerve imaging- Neurofibromatosis- Ferner, R. et al.(2004). Neurofibromatous neuropathy in neurofibromatosis 1 (NF1). J. Med. Genet. 41: Sperfeld, A. et al. (2002). Occurrence and characterization of peripheral nerve involvement in neurofibromatosis type 2. Brain, 125: Staser, K. et al. (2012). Pathogenesis of plexiform neurofibroma: tumor-stromal/hematopoetic interactions in tumor progression. Annu. Rev. Pathol. Mech. Dis., 7: Bouchard,C. et al. (1999). Clinicopathologic findings and prognosis of chronic inflammatory demyelinating ployneuropathy. Neurology, 52(3), Plexopathy mimics- Torriani, M. et al. (2009). Isciofemoral impingement syndrome: an entity with hip pain and abnormalities of the quadratus femoris muscle. AJR, 193: Koulouris, G., Connell, D. (2005). Hamstring muscle complex: an imaging review. Radiographics, 25: O Briem, S., Bui-Mansfield, L. (2007). MRI of quadratus femuris muscle tear: another cause of hip pain. AJR, 189: De Smet, A, Best, T. (2000). MR imaging of the distribution and location of acute hamstring injuries in atheletes. AJR, 174: