Intraoperative ultrasound-assisted peripheral nerve surgery

Early aggressive constriction resection for hourglass-like constriction of peripheral nerve in the upper extremity: a retrospective study

OBJECTIVES

The hourglass like constriction (HGC) of peripheral nerves is a characteristic pathological manifestation of Neuralgic Amyotrophy. Once identified, early surgical intervention is essential. However, the method of surgery is controversial, particularly regarding whether HGC needs to be excised. This study aims to explore the efficacy of early aggressive resection of HGC in the upper limb nerves.

MATERIALS AND METHODS

This retrospective study focuses on 13 nerves of spontaneous upper limb paralysis treated at our hospital from June 2019 to July 2023, in which HGC was identified during surgery. During surgery, epineurectomy and interfascicular neurolysis were performed on the constricted areas. Post-neurolysis, constriction excision was carried out if any of the following conditions were met: (1) A single constriction with constriction ≥75%. (2) Constriction combined with torsion. (3) The presence of ≥2 constrictions. Regular face-to-face follow-ups were conducted postoperatively.

RESULTS

Four cases with a single constriction of less than 75% underwent epineurotomy and interfascicular neurolysis; eight underwent constriction excision, of which four cases with a single constriction and associated torsion had direct end-to-end suturing after excision, and four had more than two constrictions treated with autologous sural nerve grafts. Postoperative follow-ups showed good recovery in all but one case, which had unique pathological features and had underwent only epineurectomy, showing moderate recovery.

CONCLUSIONS

For early surgical treatment of HGCs in peripheral nerves of the upper limbs, if severe constriction, constriction combined with torsion, or the presence of more than two constrictions are identified during surgery, aggressive constriction resection may be a better option.

Sciatic nerve fascicle differentiation on high-resolution ultrasound with histological verification: An ex vivo study

INTRODUCTION/AIMS

The development of high-resolution ultrasound (HRUS) has enabled the depiction of peripheral nerve microanatomy in vivo. This study compared HRUS fascicle differentiation to the structural depiction in histological cross-sections (HCS).

METHODS

A human cadaveric sciatic nerve was marked with 10 surgical sutures, and HRUS image acquisition was performed with a 22-MHz probe. The nerve was excised and cut into five segments for HCS preparation. Selected HCS were cross-referenced to HRUS, with sutures to improve orientation. Sciatic nerve and fascicle contouring were performed to assess nerve and fascicular cross-sectional area (CSA), fascicle count, and interfascicular distances. Three groups were defined based on HRUS fascicle differentiation in comparison to HCS, namely single fascicle (SF), fascicular cluster (FC), and no depiction (ND) group.

RESULTS

On cross-referenced HRUS to HCS images, 58% of fascicles were differentiated. On HRUS, significantly larger fascicle CSA and smaller fascicle count were observed compared with HCS. Group analysis showed that 41% of fascicles were defined as SF, 47% as FC, and 12% as ND. The mean fascicle CSA in the ND group was 0.05 mm2. Compared with the SF, the FC had significantly larger fascicle CSA (1.2 ± 0.7 vs. 0.6 ± 0.4 mm2; p < .001) and shorter interfascicular distances (0.1 ± 0.04 vs. 0.5 ± 0.3 μm; p < .001).

DISCUSSION

While HRUS can depict fascicular anatomy, only half of the fascicles visualized on HRUS directly correspond to single fascicles observed on HCS. The amount of interfascicular epineurium appears to influence the ability of HRUS to differentiate individual fascicles.

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.

Lower extremity peripheral nerve pathology: Utility of preoperative ultrasound-guided needle localization before operative intervention

Historically, the use of ultrasound (US) in the management of peripheral nervous system (PNS) pathology has been limited to diagnostic confirmation or guidance for interventional injections. This technical case series will demonstrate the utility and versatility of preoperative US-guided needle localization for the excision of lower extremity neuromas and other pathology of the PNS. Five patients with symptomatic lower extremity PNS tumors were retrospectively reviewed. This case series corroborates the technical nuances of localizing lower extremity neuromas by US-guided needle and wire placement prior to operative excision. This was achieved by a multidisciplinary team that included plastic surgery, neurosurgery, and radiology. Five patients had US-guided needle localization of a lower extremity PNS target prior to operative intervention. Three patients had lower extremity neuromas of varying origins, including the lateral femoral cutaneous nerve (LFCN), saphenous nerve, and sural nerve. The remaining two patients had a sciatic nerve sheath Schwannoma and a femoral nerve glomus tumor. Under sonographic visualization, a needle was advanced to the target perimeter and withdrawn, leaving behind a percutaneous guidewire. This technique simplified the marking of the nerve course prior to dissection and led to efficient intraoperative identification of all five PNS tumors without any complications. Preoperative US-guided needle localization led to safe, accurate, and efficient perioperative and intraoperative identification of neuromas and other PNS tumors of the lower extremity prior to excision. By reducing the challenges of nerve identification in a scarred tissue bed, this multidisciplinary approach may decrease postoperative patient morbidity.

Intraneural Lipoma: A Rare Cause of Median Nerve Compression

Intraneural lipomatous tumors are rare lesions that mostly affect the upper extremities. These slowly growing tumors can have a serious neurological and functional impact when they reach a significantly large size. We report herein a case of a 53-year-old female who presented with a large median nerve intraneural lipomatous tumor causing compression-related signs. She was treated with monoblock excision of the tumor that was completely residing between the median nerve fibers. At her last follow-up, no median nerve deficits were recorded, and the patient went to full resolution.

Label-free intraoperative nerve detection and visualization using ratiometric diffuse reflectance spectroscopy

Iatrogenic nerve injuries contribute significantly to postoperative morbidity across various surgical disciplines and occur in approximately 500,000 cases annually in the US alone. Currently, there are no clinically adopted means to intraoperatively visualize nerves beyond the surgeon's visual assessment. Here, we report a label-free method for nerve detection using diffuse reflectance spectroscopy (DRS). Starting with an in vivo rat model, fiber- and imaging-based DRS independently identified similar wavelengths that provided optimal contrast for nerve identification with an accuracy of 92%. Optical property measurements of rat and human cadaver tissues verify that the source of contrast between nerve and surrounding tissues is largely due to higher scattering in nerve and differences in oxygenated hemoglobin content. Clinical feasibility was demonstrated in patients undergoing thyroidectomies using both probe-based and imaging-based approaches where the nerve were identified with 91% accuracy. Based on our preliminary results, DRS has the potential to both provide surgeons with a label-free, intraoperative means of nerve visualization and reduce the incidence of iatrogenic nerve injuries along with its detrimental complications.

Compare the clinical value of two minimally invasive approaches to locating radial nerve in the posterior humeral approach

PURPOSE

To compare the clinical value between locating radial nerve (RN) guided by Color Doppler ultrasonography and posterior antebrachial cutaneous nerve (PACN) in the posterior humeral approach.

METHODS

The five fresh adult cadavers (ten upper arms) were selected to compare the two methods of locating the RN in the posterior humeral approach (guided by ultrasound and PACN) by measuring the operation time, the length of incision, and the area of subcutaneous free. And the comparison between the two groups was statistically analyzed by paired t-test.

RESULTS

The results of this study demonstrated that the length of incision and the area of subcutaneous free in the ultrasound group were smaller than that in the PACN group (P < 0.05), while the operation time was just the opposite (P < 0.05). However, after excluding the time of ultrasound location, the operation time in the ultrasound group was shorter than that in the PANC group, and the difference was statistically significant (P < 0.05).

CONCLUSION

The RN can be quickly and safely exposed by both methods. The ultrasound approach requires a long learning curve, but is more minimally invasive and can help determine whether the intraoperative nerve is compressed by the plate. And the PACN method requires a longer incision and a wider area of subcutaneous free, while specialized equipment and professional training for surgeons are not required. In a word, these two methods have advantages and disadvantages, so they should be selected based on the exact situation.

Radiological diagnosis of median nerve lipoma: A case report from Palestine

Lipomas are benign neoplasms that develop from adipocyte-rich adipose tissue. They affect up to 2% of the population and make up about 50% of all soft-tissue neoplasms. The most common locations for them to appear asymptomatically are the neck, upper back, proximal limbs, and chest. They typically start off as single, distinct, movable lumps. A 50-year-old man who had pain and edema in his right wrist came to our hospital. The patient's history dates back to 9 years ago, when he first began to complain of swelling in his wrist rest but no discomfort. According to a clinical examination, he has a soft, non-painful bump in his right wrist. After being monitored for 9 years with no change in the size of the tumor on his right wrist, the patient started to experience right hand pain and a weak right grasp. Magnetic resonance imaging is the preferred visualization method for examining hand tumors; it is advised to perform a preoperative complementary ultrasound or magnetic resonance imaging investigation in cases of atypical findings or nonfrequent locations of nerve compression, which are clinically interpreted as idiopathic compression.

Median and ulnar nerve fascicle imaging using MR microscopy and high-resolution ultrasound

BACKGROUND AND PURPOSE

Understanding nerve microanatomy is important as different neuropathies and some nerve neoplasms present with fascicle enlargement. The aim of our study was to gain clinically oriented knowledge on nerve fascicular anatomy using imaging modalities.

METHODS

On a cadaveric upper extremity, high-resolution ultrasound (HRUS) scan with 22 MHz probe was performed. Sections of the median and ulnar nerves were excised at the level of the distal arm and after magnetic resonance microscopy (MRM), histological cross-sections (HCS) were prepared. Cross-referencing of the MRM and HRUS images with HCS was performed. Fascicle and nerve contouring was performed with morphometric software in order to assess nerve and fascicular cross-sectional area (CSA), fascicle count, and interfascicular distances. Based on fascicle differentiation, factual fascicle (FF) group and fascicular cluster (FC) group were defined.

RESULTS

On the cross-referenced imaging material, fascicles were differentiated in 92.7% on MRM and in 57.3% on HRUS. High to very high positive correlation among imaging material was observed for the fascicle CSA. FF depiction was 30.1% on HRUS. In comparison to the FF group, the FC group had significantly larger fascicle CSA and shorter interfascicular distances.

DISCUSSION

The findings of our study contribute to understanding of fascicle depiction on imaging modalities. HRUS offers good visualization of fascicles. The capability of differentiating fascicles is modality specific and depends on the fascicle CSA and the amount of interfascicular epineurium.

Fascicular Ratio Pilot Study: High-Resolution Neurosonography-A Possible Tool for Quantitative Assessment of Traumatic Peripheral Nerve Lesions Before and After Nerve Surgery

BACKGROUND

Clinical and electrophysiological assessments prevail in evaluation of traumatic nerve lesions and their regeneration following nerve surgery in humans. Recently, high-resolution neurosonography (HRNS) and magnetic resonance neurography have gained significant importance in peripheral nerve imaging. The use of the grey-scale-based "fascicular ratio" (FR) was established using both modalities allowing for quantitative assessment.

OBJECTIVE

To find out whether FR using HRNS can assess nerve trauma and structural reorganization in correlation to postoperative clinical development.

METHODS

Retrospectively, 16 patients with operated traumatic peripheral nerve lesions were included. The control group consisted of 6 healthy volunteers. All imaging was performed with a 15 to 6 MHz ultrasound probe (SonoSite X-Porte; Fujifilm, Tokyo, Japan). FR was calculated using Fiji () on 8-bit-images ("MaxEntropy" using "Auto-Threshold" plug-in).

RESULTS

Thirteen of 16 patients required autologous nerve grafting and 3 of 16 extra-intraneural neurolysis. There was no statistical difference between the FR of nonaffected patients' nerve portion with 43.48% and controls with FR 48.12%. The neuromatous nerve portion in grafted patients differed significantly with 85.05%. Postoperatively, FR values returned to normal with a mean of 39.33%. In the neurolyzed patients, FR in the affected portion was 78.54%. After neurolysis, FR returned to healthy values (50.79%). Ten of 16 patients showed clinical reinnervation.

CONCLUSION

To our best knowledge, this is the first description of FR using HRNS for quantitative assessment of nerve damage and postoperative structural reorganization. Our results show a significant difference in healthy vs lesioned nerves and a change in recovering nerve portions towards a more "physiological" ratio. Further evaluation in larger patient groups is required.

Intraoperative Ultrasound for Peripheral Nerve Applications

Offering real-time, high-resolution images via intraoperative ultrasound is advantageous for a variety of peripheral nerve applications. To highlight the advantages of ultrasound, its extraoperative uses are reviewed. The current intraoperative uses, including nerve localization, real-time evaluation of peripheral nerve tumors, and implantation of leads for peripheral nerve stimulation, are reviewed. Although intraoperative peripheral nerve localization has been performed previously using guide wires and surgical dyes, the authors' approach using ultrasound-guided instrument clamps helps guide surgical dissection to the target nerve, which could lead to more timely operations and shorter incisions.

Preoperative Ultrasound-Guided Wire Localization of the Lateral Femoral Cutaneous Nerve

BACKGROUND

Difficulty and sometimes inability to find the lateral femoral cutaneous nerve (LFCN) intraoperatively is well known. Variabilities in the course of the nerve are well documented in the literature. In a previous paper, we defined a tight fascial canal that completely surrounds the LFCN in the proximal thigh. These 2 factors sometimes render finding the nerve intraoperatively, to treat meralgia paresthetica, very challenging.

OBJECTIVE

To explore the use of preoperative ultrasound to minimize operative time and eliminate situations in which the nerve is not found.

METHODS

Since 2011, we have used preoperative ultrasound-guided wire localization (USWL) in 19 cases to facilitate finding the nerve intraoperatively. Data were collected prospectively with recording of the timing from skin incision to identifying the LFCN; this will be referred to as the skin-to-nerve time.

RESULTS

In 2 cases, the localization was incorrect. In the 17 cases in which the LFCN was correctly localized, the skin-to-nerve time ranged from 3 min to 19 min. The mean was 8.5 min, and the median was 8 min.

CONCLUSION

Preoperative USWL is a useful technique that minimizes the time needed to find the LFCN. For the less experienced surgeon, it is extremely valuable. For the experienced surgeon, it can identify anatomical abnormalities such as duplicate nerves, which may not be readily recognizable without ultrasound. Collaboration between the surgeon and the radiologist is very important, especially in the early cases.

Pilot study of intraoperative ultrasound-guided instrument placement in nerve transection surgery for peripheral nerve pain syndromes

Surgical transection of sensory nerves in the treatment of intractable neuropathic pain is a commonly performed procedure. At times these cases can be particularly challenging when encountering obese patients, when targeting deeper nerves or those with a variable branching pattern, or in the case of repeat operations. In this case series, the authors describe their experience with ultrasound-guided surgical instrument placement during transection of a saphenous nerve in the region of prior vascular surgery in 1 patient and in the lateral femoral cutaneous nerve in 2 obese patients. The authors also describe this novel technique and provide pilot data that suggests ultrasound-assisted surgery may allow for complex cases to be completed in an expedited fashion through smaller incisions.

Peripheral nerve lipoma: Case report of an intraneural lipoma of the median nerve and literature review

Adipose lesions rarely affect the peripheral nerves. This can occur in two different ways: Direct compression by an extraneural lipoma, or by a lipoma originated from the adipose cells located inside the nerve. Since its first description, many terms have been used in the literature to mention intraneural lipomatous lesions. In this article, the authors report a case of a 62-year-old female who presented with an intraneural median nerve lipoma and review the literature concerning the classification of adipose lesions of the nerve, radiological diagnosis and treatment.