Can MR neurography of the common peroneal nerve predict a residual motor deficit in patients with foot drop?

OBJECTIVE: To determine if MR neurography of the common peroneal nerve (CPN) predicts a residual motor deficit at 12-month clinical follow-up in patients presenting with foot drop. MATERIALS AND METHODS: A retrospective search for MR neurography cases evaluating the CPN at the knee was performed. Patients were included if they had electrodiagnostic testing (EDX) within 3 months of imaging, ankle and/or forefoot dorsiflexion weakness at presentation, and at least 12-month follow-up. Two radiologists individually evaluated nerve size (enlarged/normal), nerve signal (T2 hyperintense/normal), muscle signal (T2 hyperintense/normal), muscle bulk (normal/Goutallier 1/Goutallier > 1), and nerve and muscle enhancement. Discrepancies were resolved via consensus review. Multivariable logistical regression was used to evaluate for association between each imaging finding and a residual motor deficit at 12-month follow-up. RESULTS: Twenty-three 3 T MRIs in 22 patients (1 bilateral, mean age 52 years, 16 male) met inclusion criteria. Eighteen cases demonstrated common peroneal neuropathy on EDX, and median duration of symptoms was 5 months. Six cases demonstrated a residual motor deficit at 12-month follow-up. Fourteen cases underwent CPN decompression (1 bilateral) within 1 year of presentation. Three cases demonstrated Goutallier > 1 anterior compartment muscle bulk. Multivariable logistical regression did not show a statistically significant association between any of the imaging findings and a residual motor deficit at 12-month follow-up. CONCLUSION: MR neurography did not predict a residual motor deficit at 12-month follow-up in patients presenting with foot drop, though few patients demonstrated muscle atrophy in this study.

Brachial plexus anatomy in the miniature swine as compared to human.

Brachial plexus injury (BPI) occurs when the brachial plexus is compressed, stretched, or avulsed. Although rodents are commonly used to study BPI, these models poorly mimic human BPI due to the discrepancy in size. The objective of this study was to compare the brachial plexus between human and Wisconsin Miniature SwineTM (WMSTM ), which are approximately the weight of an average human (68-91 kg), to determine if swine would be a suitable model for studying BPI mechanisms and treatments. To analyze the gross anatomy, WMS brachial plexuses were dissected both anteriorly and posteriorly. For histological analysis, sections from various nerves of human and WMS brachial plexuses were fixed in 2.5% glutaraldehyde, and postfixed with 2% osmium tetroxide. Subsequently paraffin sections were counter-stained with Masson's Trichrome. Gross anatomy revealed that the separation into three trunks and three cords is significantly less developed in the swine than in human. In swine, it takes the form of upper, middle, and lower systems with ventral and dorsal components. Histological evaluation of selected nerves revealed differences in nerve trunk diameters and the number of myelinated axons in the two species. The WMS had significantly fewer myelinated axons than humans in median (p = 0.0049), ulnar (p = 0.0002), and musculocutaneous nerves (p = 0.0454). The higher number of myelinated axons in these nerves for humans is expected because there is a high demand of fine motor and sensory functions in the human hand. Due to the stronger shoulder girdle muscles in WMS, the WMS suprascapular and axillary nerves were larger than in human. Overall, the WMS brachial plexus is similar in size and origin to human making them a very good model to study BPI. Future studies analyzing the effects of BPI in WMS should be conducted.

Inflammation after spinal cord injury: a review of the critical timeline of signaling cues and cellular infiltration.

Traumatic spinal cord injury (SCI) is a devastating neurological condition that results in a loss of motor and sensory function. Although extensive research to develop treatments for SCI has been performed, to date, none of these treatments have produced a meaningful amount of functional recovery after injury. The primary injury is caused by the initial trauma to the spinal cord and results in ischemia, oxidative damage, edema, and glutamate excitotoxicity. This process initiates a secondary injury cascade, which starts just a few hours post-injury and may continue for more than 6 months, leading to additional cell death and spinal cord damage. Inflammation after SCI is complex and driven by a diverse set of cells and signaling molecules. In this review, we utilize an extensive literature survey to develop the timeline of local immune cell and cytokine behavior after SCI in rodent models. We discuss the precise functional roles of several key cytokines and their effects on a variety of cell types involved in the secondary injury cascade. Furthermore, variations in the inflammatory response between rats and mice are highlighted. Since current SCI treatment options do not successfully initiate functional recovery or axonal regeneration, identifying the specific mechanisms attributed to secondary injury is critical. With a more thorough understanding of the complex SCI pathophysiology, effective therapeutic targets with realistic timelines for intervention may be established to successfully attenuate secondary damage.

Sustained interleukin-10 delivery reduces inflammation and improves motor function after spinal cord injury.

BACKGROUND: The anti-inflammatory cytokine interleukin-10 (IL-10) has been explored previously as a treatment method for spinal cord injury (SCI) due to its ability to attenuate pro-inflammatory cytokines and reduce apoptosis. Primary limitations when using systemic injections of IL-10 are that it is rapidly cleared from the injury site and that it does not cross the blood-spinal cord barrier. OBJECTIVE: Here, mineral-coated microparticles (MCMs) were used to obtain a local sustained delivery of IL-10 directly into the injury site after SCI. METHODS: Female Sprague-Dawley rats were contused at T10 and treated with either an intraperitoneal injection of IL-10, an intramedullary injection of IL-10, or MCMs bound with IL-10 (MCMs+IL-10). After treatment, cytokine levels were measured in the spinal cord, functional testing and electrophysiology were performed, axon tracers were injected into the brainstem and motor cortex, macrophage levels were counted using flow cytometry and immunohistochemistry, and lesion size was measured. RESULTS: When treated with MCMs+IL-10, IL-10 was significantly elevated in the injury site and inflammatory cytokines were significantly suppressed, prompting significantly less cells expressing antigens characteristic of inflammatory macrophages and significantly more cells expressing antigens characteristic of earlier stage anti-inflammatory macrophages. Significantly more axons were preserved within the rubrospinal and reticulospinal tracts through the injury site when treated with MCMs+IL-10; however, there was no significant difference in corticospinal tract axons preserved, regardless of treatment group. The rats treated with MCMs+IL-10 were the only group with a significantly higher functional score compared to injured controls 28 days post-contusion. CONCLUSION: These data demonstrate that MCMs can effectively deliver biologically active IL-10 for an extended period of time altering macrophage phenotype and aiding in functional recovery after SCI.

Ultrasound-Guided Microwave Ablation for the Management of Inguinal Neuralgia: A Preliminary Study with 1-Year Follow-up.

PURPOSE: To evaluate the feasibility and efficacy of ultrasound-guided microwave ablation for the treatment of inguinal neuralgia. MATERIALS AND METHODS: A retrospective review of 12 consecutive ultrasound-guided microwave ablation procedures was performed of 10 consecutive patients (8 men, 2 women; mean age, 41 years [range, 15-64 years]), between August 2012 and August 2016. Inclusion criteria for inguinal neuralgia included clinical diagnosis of chronic inguinal pain (average, 17.3 months [range, 6-46 months]) refractory to conservative treatment and a positive nerve block. Pain response-reduction of pain level and duration and percent pain reduction using a 10-point visual analog scale (VAS) at baseline and up to 12 months after the procedure-was measured. Nine patients had pain after the inguinal hernia repair, and 1 patient had pain from the femoral artery bypass procedure. The microwave ablation procedure targeted the ilioinguinal nerve in 7 cases, the genitofemoral nerve in 4 cases, and the iliohypogastric nerve in 1 case. RESULTS: Average baseline VAS pain score was 6.1 (standard deviation, 2.5). Improved pain levels immediately after the procedure and at 1, 6, and 12 months were statistically significant (P = .0037, .0037, .0038, .0058, respectively). Also, 91.7% (11/12) of the procedures resulted in immediate pain relief and at 1 month and 6 months. At 12 months, 83.3% (10/12) of patients had an average of 69% ± 31% pain reduction. Percent maximal pain reduction was 93% ± 14% (60%-100%), and the average duration of clinically significant pain reduction was 10.5 months (range, 0-12 months.). No complications or adverse outcomes occurred. CONCLUSIONS: Ultrasound-guided microwave ablation is an effective technique for the treatment of inguinal neuralgia after herniorrhaphy.

Peroneal nerve decompression.

Peroneal neuropathy is a common pathology encountered by neurosurgeons. Symptoms include pain, numbness, and foot drop. When secondary to compression of the nerve at the fibular head, peroneal (fibular) nerve release is a low-risk procedure that can provide excellent results with pain relief and return of function. In this video, the authors highlight key operative techniques to ensure adequate decompression of the nerve while protecting the 3 major branches, including the superficial peroneal nerve, deep peroneal nerve, and recurrent genicular (articular) branches. Key steps include positioning, circumferential nerve dissection, fascial opening, isolation of the major branches, and closure. The video can be found here: https://youtu.be/0y9oE8w1FIU .

Lateral femoral cutaneous nerve transposition: Renaissance of an old concept in the light of new anatomy.

Meralgia paresthetica causes pain in the anterolateral thigh. Most surgical procedures involve nerve transection or decompression. We conducted a cadaveric study to determine the feasibility of lateral femoral cutaneous nerve (LFCN) transposition. In three cadavers, the LFCN was exposed in the thigh and retroperitoneum. The two layers of the LFCN canal superficial and deep to the nerve were opened. The nerve was then mobilized medially away from the ASIS, by cutting the septum medial to sartorius. It was possible to mobilize the nerve for 2 cm medial to the ASIS. The nerve acquired a much straighter course with less tension. A new technique of LFCN transposition is presented here as an anatomical feasibility study. The surgical technique is based on the new understanding of the LFCN canal. Clin. Anat. 30:409-412, 2017. © 2017 Wiley Periodicals, Inc.

Intraoperative ultrasound-assisted peripheral nerve surgery.

Historically, peripheral nerve surgery has relied on landmarks and fairly extensive dissection for localization of both normal and pathological anatomy. High-resolution ultrasonography is a radiation-free imaging modality that can be used to directly visualize peripheral nerves and their associated pathologies prior to making an incision. It therefore helps in localization of normal and pathological anatomy, which can minimize the need for extensive exposures. The authors found intraoperative ultrasound (US) to be most useful in the management of peripheral nerve tumors and neuromas of nerve branches that are particularly small or have a deep location. This study presents the use of intraoperative US in 5 cases in an effort to illustrate some of the applications of this useful surgical adjunct.

Preoperative Ultrasound-Guided Localization of the Lateral Femoral Cutaneous Nerve: From Guide Wire to Novel Clip.

BACKGROUND AND OBJECTIVE: Lateral femoral cutaneous nerve (LFCN) decompression and transposition are surgical treatment options for meralgia paresthetica. Identifying the LFCN during surgery may be challenging, and preoperative localization is a valuable adjunct in this case. The objective of this study was to explore a new technique using preoperative ultrasound-guided clip localization (USCL) of the LFCN. METHODS: After Institutional Review Board approval, data were collected on patients who underwent both preoperative ultrasound-guided wire localization (USWL) and USCL over the past 13 years. Skin-to-nerve time was calculated prospectively. RESULTS: Fifty-six patients were identified, 51 had USWL and 5 had USCL; the skin-to-nerve median time was 7.5 and 6 minutes, respectively. Six wires were misplaced, and this was at the beginning of utilization of the USWL technique. There were no nerve injury, infection, or bleeding complications related to either wire or clip placement. CONCLUSION: USWL or USCL is safe and time-efficient in LFCN surgeries.

Anatomical Proximity Between Sciatic Nerve and Ischial Spine and its Relationship to the Development of Deep Gluteal Pain Syndrome.

OBJECTIVE: Deep gluteal syndrome (DGS) is a medical diagnosis in which the pathoanatomy of the subgluteal space contributes to pain. The growing recognition that gluteal neuropathies can be associated with the presence of a bone-neural conflict with irritation or compression may allow us to shed some light on this pathology. This study aims to determine whether the location of the sciatic nerve (SN) in relation to the ischial spine (IS) contributes to the development of DGS. METHODS: The SN - IS relationship was analyzed based on magnetic resonance imaging (MRI) in 15 surgical patients (SPs), who underwent piriformis release, and in 30 control patients who underwent MRI of the pelvis for reasons unrelated to sciatica. The SN exit from the greater sciatic foramen was classified as either zone A (medial to the IS); zone B (on the IS); or zone C (lateral to the IS). RESULTS: The SN was significantly closer to the IS in SPs than in MRI controls (P = 0.014). When analyzing patients of similar age, SNs in SPs were significantly closer (P = 0.0061) to the IS, and located in zone B significantly more (P = 0.0216) as compared to MRI controls. Patients who underwent surgery for piriformis release showed a significant decrease in pain postoperatively (P < 0.0001). CONCLUSIONS: The results from this study suggest that the relationship between the IS and SN may play a role in the development of DGS. This may also help establish which patients would benefit more from surgical intervention.

Anatomical Relationships of the Sciatic Nerve and Pudendal Nerve to the Ischial Spine as They Exit the Greater Sciatic Foramen.

OBJECTIVE: Deep gluteal syndrome is a clinical condition in which discomfort may arise due to the pathoanatomy of the subgluteal space. We conducted an anatomical exploration to categorize the relationship of the piriformis muscle, sciatic nerve (SN), and pudendal nerve (PN) to the ischial spine (IS) and sacrospinous ligament. METHODS: We analyzed 22 cadavers. The piriformis muscle, SN, and PN were exposed through either a transgluteal approach or a gluteal flap. The relationship of the neural structures to the IS, sacrospinous ligament, and ischial bone as they exit the greater sciatic foramen was observed, and the exit zones were classified as zone A, medial to the IS (entirely on sacrospinous ligament); zone B, on the IS; and zone C, lateral to the IS (entirely on ischial bone). RESULTS: The SN was observed either in zone B or zone C in all specimens. The PN was found to be in either zone A or zone B in 97.6% of specimens. The most common combinations were SN in zone B and PN in zone A (type I), and SN in zone C and PN in zone B (type II). CONCLUSIONS: The results from this study show clear anatomical differences in the SN-PN relationship, which may play a role in pain seen in deep gluteal syndrome. Moreover, classification of the SN-IS and PN-IS relationships described in this article will help describe different pathologies affecting the deep gluteal area.

Comparison of nylon, vicryl, and fibrin glue for nerve grafting in rats.

OBJECTIVES: For nerve injuries, not amendable to tensionless epineural coaptation of the nerve, autografts are the preferred treatment. Although absorbable sutures are not recommended for nerve repair, there is no evidence that non-absorbable sutures are superior to absorbable sutures. This study aims to assess the effectiveness of non-absorbable monofilament nylon sutures, absorbable monofilament vicryl sutures, and fibrin glue when used for nerve grafting. METHODS: Lewis rats (N = 32) were subjected to a sciatic nerve transection and randomly assigned to a group: graft with Nylon, graft with Vicryl, graft with Fibrin Glue, or no graft. Motor function, sensory function, and thermal pain were assessed during a 12-week recovery period, and immunohistochemistry was used to assess macrophage response. RESULTS: At 12 weeks, the Vicryl and Nylon groups had significantly larger ankle angles at to lift off, which is a measure of motor function, compared to injured controls (p < 0.05). Grafted rats displayed no difference in thermal response but hypersensitivity to mechanical stimuli compared to the uninjured hindlimb. The Nylon, Vicryl, and Fibrin Glue groups all had significantly less atrophy of the gastrocnemius muscle compared to injured controls (p < 0.0001). In the Fibrin Glue group, 3/9 grafts did not incorporate. The Nylon group had significantly less (p = 0.0004) axon growth surrounding the suture holes compared to the Vicryl group. There were no differences in the axon counts, motor neurons, or sensory neurons between all grafted rats. CONCLUSIONS: These results demonstrate that vicryl sutures work just as well as nylon for nerve recovery after injury and grafting.

Large vertebral artery pseudoaneurysm masquerading as a schwannoma: illustrative case.

BACKGROUND: Extracranial vertebral aneurysms or pseudoaneurysms are rare and result primarily from trauma. Large pseudoaneurysms can masquerade as mass lesions, making it challenging to identify the correct diagnosis. OBSERVATIONS: This is a case report in which a large vertebral pseudoaneurysm posed as a schwannoma and biopsy was attempted. It was later identified as a vascular lesion and treated appropriately with no complications. LESSONS: Vascular etiologies should always be included in the differential diagnosis of spine and nerve pathologies especially lesions that are in the vicinity of major vascular channels such as the transverse foramina of the cervical spine.

Lateral femoral cutaneous nerve transposition.

Lateral femoral cutaneous neuropathy, also known as meralgia paresthetica, is a pathology commonly encountered by neurosurgeons. Symptoms include numbness, tingling, and burning pain over the anterolateral thigh due to impingement on the lateral femoral cutaneous nerve (LFCN). Surgical treatment has traditionally involved nerve release or neurectomy. LFCN transposition is a relatively new approach that can provide excellent symptomatic relief. In this video, the authors highlight key operative techniques to ensure easy identification, adequate decompression, and transposition of the nerve. Key steps include ultrasound-guided wire localization, superficial decompression, opening of the inguinal ligament, deep decompression, and medial transposition. The video can be found here: https://stream.cadmore.media/r10.3171/2022.10.FOCVID2289.

A combined, supraclavicular, infraclavicular, transaxillary, and posterior subscapular approaches for en bloc resection of giant myxofibrosarcoma.

Background: Myxofibrosarcoma (MFS) is a rare and locally infiltrative tumor that commonly occurs in extremities in older adults; however, truncal and head and neck cases have been reported. They are characterized by multinodular growth, incomplete fibrous septa, and myxoid stroma. Surgical resection is the mainstay of treatment. Case Description: The authors report a case of a combined, supraclavicular, infraclavicular, transaxillary, and posterior subscapular approaches for resection of giant MFS. Conclusion: The anatomical complexity and rarity of tumors involving the brachial plexus impose many challenges onto surgeons performing surgical resections. Treatment choices and surgical outcomes rely heavily on meticulous multidisciplinary planning, anatomical knowledge, careful dissection, and extent of resection. This case is unique in utilizing four different approaches to the brachial plexus to resect one tumor.

Peroneal Nerve Repair with Cross-Bridge Ladder Technique: Parallel End-to-Side Neurorrhaphies.

Background Multiple nerve transfer techniques are used to treat patients with nerve injuries when a primary repair is not possible. These techniques are categorized to end-to-end, end-to-side, and side-to-side neurorrhaphy. Our study aims to explore the utility of the cross-bridge ladder technique (H-shaped), which has shown promising results in animal models and probably underutilized clinically. Methods Four patients with significant loss of ankle dorsiflexion were seen in the clinic and underwent evaluation, including electrodiagnostic studies. A cross-bridge ladder repair technique was used between the tibial nerve as the donor and the common peroneal nerve as the recipient via one or two nerve grafts coapted in parallel with end-to-side neurorrhaphies. Dorsiflexion strength was measured preoperatively using the Medical Research Council (MRC) grading system and at each postoperative follow-up appointment. Results All four patients had suffered persistent and severe foot drop (MRC of 0) following trauma that had occurred between 6 and 15 months preoperatively. Three of the four patients improved to an MRC of 2 several months postoperatively. The last patient had an immediate improvement to an MRC of 2 by his first month and had a complete recovery of ankle dorsiflexion within 4 months from surgery. Conclusion We demonstrate the utility and clinical outcomes of the cross-bridge ladder technique in patients with persistent and prolonged foot drop following trauma. Both early and late recovery were seen while all patients regained motor function, with some patients continuing to improve up to the most recent follow-up. IRB Approval: Obtained 2013-1411-CP005.

Gait analysis in swine, sheep, and goats after neurologic injury: a literature review.

Medical research on neurologic ailments requires representative animal models to validate treatments before they are translated to human clinical trials. Rodents are the predominant animal model used in neurological research despite limited anatomic and physiologic similarities to humans. As a result, functional testing designed to assess locomotor recovery after neurologic impairment is well established in rodent models. Comparatively, larger, more clinically relevant models have not been as well studied. To achieve similar locomotor testing standardization in larger animals, the models must be accessible to a wide array of researchers. Non-human primates are the most relevant animal model for translational research, however ethical and financial barriers limit their accessibility. This review focuses on swine, sheep, and goats as large animal alternatives for transitional studies between rodents and non-human primates. The objective of this review is to compare motor testing and data collection methods used in swine, sheep, and goats to encourage testing standardization in these larger animal models. The PubMed database was analyzed by searching combinations of swine, sheep, and goats, neurologic injuries, and functional assessments. Findings were categorized by animal model, data collection method, and assessment design. Swine and sheep were used in the majority of the studies, while only two studies were found using goats. The functional assessments included open pen analysis, treadmill walking, and guided free walking. Data collection methods included subjective behavioral rating scales and objective tools such as pressure-sensitive mats and image-based analysis software. Overall, swine and sheep were well-suited for a variety of assessment designs, with treadmill walking and guided free walking offering the most consistency across multiple trials. Data collection methods varied, but image-based gait analysis software provided the most robust analysis. Future studies should be conducted to standardize functional testing methods after neurologic impairment in large animals.

Inadvertent insertion of nasogastric tube into the brain stem and spinal cord after endoscopic skull base surgery.

A significant number of neurosurgical patients require feeding tube placement via a nasogastric route. It is used as a temporary access for enteral feeding until patients are able to swallow or receive permanent access. Despite how commonly feeding tubes are used, they are not without potential complications. We report a case of inadvertent placement of small-bore feeding tube into the brain stem and spinal cord in a patient with a history of previous endoscopic transnasal resection of clival chordoma. We discuss the management of this complication and the strategies that have been developed to avoid this complication in the future.

Benign eccrine spiradenoma imitating a nerve sheath tumor: illustrative case.

BACKGROUND: Benign eccrine spiradenoma is a rare tumor arising from the sweat glands and is a pathology that is almost never encountered in routine neurosurgical practice. Although this is a rare pathology, it is one that should be included in the differential diagnosis for a patient presenting with a painful, subcutaneous mass, because it can guide further treatment considerations. OBSERVATIONS: The authors present a case of benign eccrine spiradenoma that mimicked a nerve sheath tumor in clinical presentation, imaging characteristics, and gross appearance. LESSONS: Complete local excision of these lesions is the gold standard treatment, because they are painful, and there are reports of local recurrence and malignant degeneration with incomplete resection. For this reason, neurosurgeons should be sure to include this in the differential diagnosis of a patient with a painful, subcutaneous mass, because it may help to guide management decisions.

The Window Test: A Simple Bedside Method to Detect Radial Deviation of the Wrist Commonly Seen in Posterior Interosseous Nerve Palsy.

BACKGROUND: Posterior interosseous nerve palsy (PINP) is a disorder caused by damage to the posterior interosseous nerve, resulting in weak extension of the wrist and fingers as well as radial deviation of the wrist. METHODS: This study analyzed a new type of evaluation for PINP in hopes of increasing ease of diagnosis and earlier detection of the disorder. The window test is performed by the examiner laying hands on the ulnar aspect of the patient's pronated forearm while the patient tries to extend the wrist. A positive test is obtained when a gap (window) appears between the examiner's forearm and the patient's hand. Laypeople, medical students, residents, and practicing providers were assessed prospectively on their ability to correctly diagnose PINP by observing one hand, by observing both hands and by using the window test. RESULTS: The window test was consistently found to be the most effective method of evaluation, as it increased the accuracy of diagnosis in all groups surveyed. Additionally, case studies were performed using the window test on patients, further demonstrating the efficacy of the test by confirming wrist radial deviation. CONCLUSIONS: The window test introduces a reference frame making it easier to assess wrist radial deviation and offering a simple evaluation that can be administered by virtually anyone. These findings indicate that the implementation of the window test will increase the accuracy and effectiveness of PINP diagnosis, thus allowing early diagnosis and better management.