Postoperative Imaging of Peripheral Nerves: Review of Surgical Techniques, Expected Findings, and Complications.

Management of peripheral nerve injury

To distinguish early magnetic resonance (MR) imaging findings in postoperative diskitis from normal postoperative changes, a prospective study was performed in 15 asymptomatic patients (17 disk levels) who underwent uncomplicated lumbar diskectomy and seven patients with proved postoperative diskitis. On postoperative MR images, four of the asymptomatic patients had a finding that could also be seen in patients with diskitis. Gadolinium enhancement was useful in making the distinction and occurred as follows: (a) vertebral bone marrow: all seven diskitis patients and one asymptomatic patient; (b) disk space: five diskitis patients and three asymptomatic patients; and (c) posterior anulus fibrosus: all seven diskitis patients and 13 asymptomatic patients (14 of 17 levels). This entire triad of findings, which is strongly suggestive of postoperative diskitis, was not seen in any of the asymptomatic patients. Changes in the disk space and adjacent bone marrow on pre- and post-contrast MR images after routine diskectomy are uncommon and should not be assumed to be normal postoperative changes without careful consideration and analysis for early diskitis.

Theme: Promoting anatomy to enlighten safe and effective clinical practice
 It is with a greater honor that I welcome you to this Anatomy Annual Congress, the first of its kind in Rwanda. Anatomy is an essential fundamental science in medical education and medical practice and it deserve to be vibrant scientifically. The S-CAR have been founded with the aim of growing the anatomy sciences and this congress is a wonderful outcome of this common commitment. The congress has 4 events that include: a pre-conference workshop on the peripheral nervous system, the S-CAR annual congress, the scientific conference and the world anatomy day (WAD).
 Reinforcing the importance of the PNS, Dr. David HAKIZIMANA, a Senior Consultant Neurosurgeon wrote this, I quote: “Peripheral nerve surgery is used to improve function and minimize pain and disability in people with peripheral nerve disorders, such as acute nerve injuries, entrapment neuropathies, and nerve sheath tumors. It involves rerouting healthy nerves to take over the function of the nerves affected by injury, disease, or condition. Surgical treatment for peripheral nerve injuries involves a team which may include: neurosurgeons, plastic surgeons, orthopedic surgeons. Globally the status of peripheral nerve surgery practice within the global landscape of surgery has long been in the shadow of the more prominent areas. The reasons are many, one of them plausibly being the conceptual frame of the very word “peripheral”, which evoke the notions of marginality and lesser importance especially for neurosurgeons. Some of the related common misconceptions are that neurological deficit in peripheral nerve injury is permanent and irreversible, that peripheral nerves do not have the ability to regenerate, that the results of surgical treatment are insignificant. In Rwanda and Africa in general peripheral nerve surgery in almost non-existing or at embryonic phase at best. Although peripheral nerve surgery is not a life-saving surgery, it has been proved to be a life-changing surgery, with a major impact on the quality of patient’s life, as it improves the patient’s ability to perform every day and professional activities and thus affects his/her physical and psychological well-being. Moreover, since most patients with peripheral nerve injuries and brachial plexus injuries belong to the working-age population, peripheral nerve surgery also has substantial socioeconomic implications. Contrary to the previously held view, the peripheral nerve system has been shown to have a huge regeneration potential, with significant results enhanced by different modalities of stimulation, whereby recent research on brain plasticity indicates that experience-dependent reorganization of neural networks plays an important role in functional recovery. For all these reasons, systematic research, education, and practice in peripheral nerve surgery is definitely worth the effort. The aim of this course will be to train residents and interested surgeons from Rwanda in peripheral nerve surgery skills”. The rich scientific conference program with 37 presentations subdivided in sessions on medical education, congenital defects, anatomy and anatomical variations, neurosciences, free presentations, closure lecture, scientific forum for PhD and MSC candidates, cadavers for education and research will give to you an excellent experience. On behalf of S-CAR, I am grateful to the sponsors (MoH, UR, UGHE, AUCA-ASOME, Operation Smile, CHUK and MMI).

Extensive scar tissue formation after peripheral nerve injury or surgery is a common problem. To avoid perineural scarring, implanting a mechanical barrier protecting the nerve from inflammation processes in the perineural environment has shown promising results for functional recovery. This study investigates the potential of an acellular collagen-elastin matrix wrapped around a peripheral nerve after induction of scar tissue formation. In the present study, 30 Lewis rats were separated into three groups and sciatic nerve scarring was induced with 2.5% glutaraldehyde (GA-CM) or 2.5% glutaraldehyde with a supplemental FDA-approved acellular collagen-elastin matrix application (GA+CM). Additionally, a sham group was included for control. Nerve regeneration was assessed by functional analysis using the Visual Statisc Sciatic Index (SSI) and MR neurography during the 12-week regeneration period. Histological and histomorphometry analysis were performed to evaluate the degree of postoperative scar tissue formation. Histological analysis showed an extensive scar tissue formation for GA-CM. Connective tissue ratio was significantly (p < 0.009) reduced for GA+CM (1.347 ± 0.017) compared to GA-CM (1.518 ± 0.057). Similarly, compared to GA+CM, MR-Neurography revealed extensive scar tissue formation for GA-CM with a direct connection between nerve and paraneural environment. Distal to the injury site, quantitative analysis presented significantly higher axon density (p = 0.0145), thicker axon diameter (p = 0.0002) and thicker myelinated fiber thickness (p = 0.0008) for GA+CM compared to GA-CM. Evaluation of functional recovery revealed a significantly faster regeneration for GA+CM. The supplemental application of an acellular collagen-elastin matrix showed beneficial effects in histological, radiological, and functional analysis. Therefore, applying a collagen-elastin matrix around the nerve after peripheral nerve injury or surgery may have beneficial effects on preventing scar tissue formation in the long run. This represents a feasible approach to avoid scar tissue formation in peripheral nerve surgery.

: This presentation aims to describe the imaging patterns of normal postoperative (post-op) cranium and usual and unusual complications of various cranial surgeries. Many radiologists are dealing with imaging of postoperative cranium in their daily practice. They should be familiar with various types of cranial surgeries, including burr holes, craniotomy, craniectomy, and cranioplasty, as well as normal postoperative changes and complications of each cranial surgery. Findings and procedure details: Imaging is of significant importance in the routine postoperative follow-up of neurosurgical cranial procedures. Computed tomography (CT) is the first choice imaging modality. However, magnetic resonance imaging (MRI) may be needed for early or better detection of some complications, especially for ischemia or infections. The most important mainstay of interpreting a post-op cranium is to distinguish normal post-op changes from complications. The first step is familiarity with the normal anatomy. Although the vast majority of post-op CT or MR images are not normal looking, most of their changes are expected (normal) post-op changes which do not adversely affect the patient outcome. Scalp swelling, simple pneumocephalus, small size hemorrhages or edema in surgical site, extradural or subdural fluid collections and dural or surgical site enhancement in early post-op period are examples of normal post-op changes. Some complications are seen only in special procedures (such as plunging of burr holes or extracranial herniation, trephine syndrome, or external brain tamponade in craniectomy) and others are common for all procedures. Skull fractures, infection (extradural abscess, subdural empyema, and bone flap infection), hemorrhage (subdural, extradural, parenchymal hematoma) and pneumocephalous are common complications of all neurosurgical procedures. The most important role of radiologists is to recognize the less common, but life threatening, post-op complications such as tension pneumocephalus, external brain tamponade and paradoxical herniation. Early and accurate diagnosis is essential for improving the outcome. Since some findings may be seen in asymptomatic patients (pseudocomplications), one should always consider the patients clinical status when interpreting the post-op images. Interpretation of post-op cranium images requires knowledge of the normal anatomy, types of craniosurgery, and differentiating normal post-op changes from complications. Reporting a complication, especially a life threatening one, always should be done with clinical correlation.

Peripheral nerve injuries and brachial plexus injuries are relatively frequent. Significance of these injuries lies in the fact that the majority of patients with these types of injuries constitute working population. Since these injuries may create disability, they present substantial socioeconomic problem nowadays. This article will present current state-of-the-art achievements of minimal invasive brachial plexus and peripheral nerve surgery. It is considered that the age of the patient, the mechanism of the injury, and the associated vascular and soft-tissue injuries are factors that primarily influence the extent of recovery of the injured nerve. The majority of patients are treated using classical open surgical approach. However, new minimally invasive open and endoscopic approaches are being developed in recent years—endoscopic carpal and cubital tunnel release, targeted minimally invasive approaches in brachial plexus surgery, endoscopic single-incision sural nerve harvesting, and there were even attempts to perform endoscopic brachial plexus surgery. The use of the commercially available nerve conduits for bridging short nerve gap has shown promising results. Multidisciplinary approach individually designed for every patient is of the utmost importance for the successful treatment of these injuries. In the future, integration of biology and nanotechnology may fabricate a new generation of nerve conduits that will allow nerve regeneration over longer nerve gaps and start new chapter in peripheral nerve surgery.

Google Trends Analysis of Peripheral Nerve Disease and Surgery

Peripheral nerve injuries commonly occur due to trauma, like a traffic accident. Peripheral nerves get severed, causing motor neuron death and potential muscle atrophy. The current golden standard to treat peripheral nerve lesions, especially lesions with large (≥ 3 cm) nerve gaps, is the use of a nerve autograft or reimplantation in cases where nerve root avulsions occur. If not tended early, degeneration of motor neurons and loss of axon regeneration can occur, leading to loss of function. Although surgical procedures exist, patients often do not fully recover, and quality of life deteriorates. Peripheral nerves have limited regeneration, and it is usually mediated by Schwann cells and neurotrophic factors, like glial cell line-derived neurotrophic factor, as seen in Wallerian degeneration. Glial cell line-derived neurotrophic factor is a neurotrophic factor known to promote motor neuron survival and neurite outgrowth. Glial cell line-derived neurotrophic factor is upregulated in different forms of nerve injuries like axotomy, sciatic nerve crush, and compression, thus creating great interest to explore this protein as a potential treatment for peripheral nerve injuries. Exogenous glial cell line-derived neurotrophic factor has shown positive effects in regeneration and functional recovery when applied in experimental models of peripheral nerve injuries. In this review, we discuss the mechanism of repair provided by Schwann cells and upregulation of glial cell line-derived neurotrophic factor, the latest findings on the effects of glial cell line-derived neurotrophic factor in different types of peripheral nerve injuries, delivery systems, and complementary treatments (electrical muscle stimulation and exercise). Understanding and overcoming the challenges of proper timing and glial cell line-derived neurotrophic factor delivery is paramount to creating novel treatments to tend to peripheral nerve injuries to improve patients’ quality of life.

BACKGROUND: The amount of published data related to peripheral nerve blast injuries is limited. AIM: The study was aimed at determining the accuracy and sensitivity and assessing the specificity of ultrasound in the diagnosis of peripheral nerve injuries in mine blast trauma. METHODS: A total of 159 patients (274 peripheral nerves) were examined. Ultrasound was performed according to the standard technique using a HI VISION Avius HITACHI scanner with an EUP-L74M linear transducer (a frequency range of 513 MHz) and a preset musculoskeletal system ultrasound program. The duration of nerve injuries ranged from 2 to 273 days. All patients were men aged 20 to 48 years. Peripheral nerves were damaged as a result of mine blast trauma. Statistical analysis was used to assess sensitivity, specificity, and diagnostic accuracy. These characteristics were calculated according to the qualitative assessment of surgical intervention, the results of conservative treatment, and the method under study (ultrasound). RESULTS: A total of 274 damaged peripheral nerves were examined. The Group 1 included 93 (34%) nerves that required surgical intervention. In Group 2, consisting of 181 (66%) nerves, conservative treatment was used. Most of the nerves (47 [51%]) in Group 1 were damaged due to the compression effects of scarring in the surrounding tissues. Seventeen (18%) partial violations of the anatomical integrity of nerves with the formation of intramural and marginal neuromas were detected. Multiple and single nerve injuries were observed in 95 (59.7%) and 64 people (40.3%), respectively. Peripheral nerves of the upper extremities were damaged more frequently (185 [67.5%]), whereas nerves of the lower extremities were damaged in 89 (32.5%) cases. Ultrasound showed an increase in the cross-sectional area of nerves, blurred contours, decreased echogenicity, and changes in the bundle structure up to the complete absence of differentiation of individual fascioculi. The formation of neuromas was observed in complete and partial nerve ruptures. All 93 nerves in Group 1 underwent surgical intervention, particularly, external neurolysis (32 [34%]), internal neurolysis (15 [16%]), nerve suture (15 [16%]), excision of neuroma followed by microsurgical epineural suture (18 [19%]), and autoneural plasty (11 [12%]). In 2 (3%) cases, a decision was made to abstain from plasty and perform a tendon transposition due to a pronounced diastasis. All patients of Group 2 were shown to have a wait-and-see approach, and conservative therapy was prescribed. In 179 (99%) cases, complete recovery of sensory and motor activity was observed within 21 days. In 2 (1%) patients, a repeated ultrasound was performed due to no effect of treatment. Compression by scar tissues was revealed, and surgical intervention was made. CONCLUSIONS: In mine-explosive impact, ultrasound is the leading method for diagnosing peripheral nerve injuries. Ultrasound with sensitivity of 97.8% and specificity of 98.8% reveals lesions for which surgical treatment is indicated. The diagnostic accuracy is 98.5%.

To determine the echographic criterias that allow to establish the degree of nerve damage after a gunshot injury without neurotomy. Material and methods. The results of a comprehensive study of 30 peripheral nerves after reconstructive surgeries were analyzed. The cause of nerve damage was a gunshot injury. The condition of the peripheral nerves was assessed using ultrasound (US) at the preoperative stage and intraoperatively. The postoperative material was microscopically examined. The US results were compared with the results of the histology. Of the 30 nerve trunks, 12 (40%) had signs of complete disruption of the anatomical integrity with the formation of terminal neuromas. In 18 (60%) nerves, there were signs of partial rupture of fibers. At the preoperative US the echostructure of the nerves changed from a slight disruption of the nerve fascicular structure to a complete loss of differentiation into fascicles with the formation of neuromas. Neuromas made up from 10 to 100% of the cross-sectional area (CSA). Histology of neuromas revealed areas of substitution perineural fibrosis with dystrophic changes in regenerating axons of varying severity. The following surgeries were performed to restore the nerves integrity: neurorrhaphy – 6 (20%), neurotransplantation – 15 (50%), intra-trunk neurolysis – 9 (30%). Depending on the depth and extent of the nerve trunk damage, we identified 3 groups of patients. Group 1: 12 (40%) nerve trunks with mild or moderate dystrophic changes. Intraoperatively, the external characteristics of the damaged area of the nerve didn’t differ significantly from the healthy one. Neuromas involved up to 25% of the CSA of nerves, no more than 1.5 cm in length at intraoperative US. Neurolysis was performed in 9 cases, neurorrhaphy in 3 cases. Group 2: 7 (23%) nerves with pronounced degenerative changes. During the operation, the external characteristics of the nerve damaged area were different and stood out against the background of the healthy area of the nerve. Neuromas involved up 25 to 50% of the PPS of the nerve, length from 1.5 to 5.0 cm at intraoperative US, were operated on: 4 nerves – neurorrhaphy; 3 nerves - neurotransplantation. Group 3: 11 (37%) nerves with subtotal or total nerve damage. Such changes highlighted the nerve injured area, leaving no doubt about its damage during the operation. Neuromas replaced 50-100% of the PPS of the nerve, length of 5.0 cm or more: neurotransplantation was performed in 11 cases. With the intact nerve fascicular structure, most of its fascicles are morphologically unchanged or have moderately pronounced degenerative changes, not always noticeable macroscopically, which requires intraoperative US to exclude neuroma. Neuromas that make up to 25% of the entire PPS of the nerve, with a length of no more than 1.5 cm, are often subject to endoneurolysis. Thickening of individual or most of the fascicles, morphologically manifests itself as pronounced degenerative changes in the fascicles with substitution perineural fibrosis. The changes are not always noticeable macroscopically, which may require intraoperative US. With neuromas that make up from 25 to 50% of the entire PPS of the nerve with a pathological lesion length of up to 2.0 cm, neurorrhaphy will be required, more than 2.0 cm - neurotransplantation. The absence of the nerve fascicular structure is morphologically manifested by subtotal replacement of the nerve by perineural fibrosis with the formation of a neuroma, which is always manifested macroscopically and doesn’t require additional intraoperative US. In the presence of a neuroma, performing from 50 to 100% of the entire PPS of the nerve and the length of the pathological focus up to 5.0 cm, neurorrhaphy is more often performed, more than 5.0 cm - neurotransplantation.

Chapter 45 - The surgery of peripheral nerves (including tumors)

Chapter 25 Phototherapy in Peripheral Nerve Injury: Effects on Muscle Preservation and Nerve Regeneration

Total hip arthroplasty and hip preservation surgeries have substantially increased over the past few decades. Musculoskeletal imaging and interventions are cornerstones of comprehensive postoperative care and surveillance in patients undergoing established and more recently introduced hip surgeries. Hence the radiologist's role continues to evolve and expand. A strong understanding of hip joint anatomy and biomechanics, surgical procedures, expected normal postoperative imaging appearances, and postoperative complications ensures accurate imaging interpretation, intervention, and optimal patient care. This article presents surgical principles and procedural details pertinent to postoperative imaging evaluation strategies after common hip surgeries, such as radiography, ultrasonography, computed tomography, and magnetic resonance imaging. We review and illustrate the expected postoperative imaging appearances and complications following chondrolabral repair, acetabuloplasty, osteochondroplasty, periacetabular osteotomy, realigning and derotational femoral osteotomies, and hip arthroplasty.

Total hip arthroplasty and hip preservation surgeries have substantially increased over the past few decades. Musculoskeletal imaging and interventions are cornerstones of comprehensive postoperative care and surveillance in patients undergoing established and more recently introduced hip surgeries. Hence the radiologist's role continues to evolve and expand. A strong understanding of hip joint anatomy and biomechanics, surgical procedures, expected normal postoperative imaging appearances, and postoperative complications ensures accurate imaging interpretation, intervention, and optimal patient care. This article presents surgical principles and procedural details pertinent to postoperative imaging evaluation strategies after common hip surgeries, such as radiography, ultrasonography, computed tomography, and magnetic resonance imaging. We review and illustrate the expected postoperative imaging appearances and complications following chondrolabral repair, acetabuloplasty, osteochondroplasty, periacetabular osteotomy, realigning and derotational femoral osteotomies, and hip arthroplasty.

Background Acute pain is a warning mechanism that exists to prevent tissue damage, however pain can outlast its protective purpose and persist beyond injury, becoming chronic. Chronic Pain is maladaptive and needs addressing as available medicines are only partially effective and cause severe side effects. There are profound differences between acute and chronic pain. Dramatic changes occur in both peripheral and central pathways resulting in the pain system being sensitised, thereby leading to exaggerated responses to noxious stimuli (hyperalgesia) and responses to non-noxious stimuli (allodynia). Critical role for immune system cells in chronic pain Preclinical models of neuropathic pain provide evidence for a critical mechanistic role for immune cells in the chronicity of pain. Importantly, human imaging studies are consistent with preclinical findings, with glial activation evident in the brain of patients experiencing chronic pain. Indeed, immune cells are no longer considered to be passive bystanders in the nervous system; a consensus is emerging that, through their communication with neurons, they can both propagate and maintain disease states, including neuropathic pain. The focus of this review is on the plastic changes that occur under neuropathic pain conditions at the site of nerve injury, the dorsal root ganglia (DRG) and the dorsal horn of the spinal cord. At these sites both endothelial damage and increased neuronal activity result in recruitment of monocytes/macrophages (peripherally) and activation of microglia (centrally), which release mediators that lead to sensitisation of neurons thereby enabling positive feedback that sustains chronic pain. Immune system reactions to peripheral nerve injuries At the site of peripheral nerve injury following chemotherapy treatment for cancer for example, the occurrence of endothelial activation results in recruitment of CX3C chemokine receptor 1 (CX3CR1)-expressing monocytes/macrophages, which sensitise nociceptive neurons through the release of reactive oxygen species (ROS) that activate transient receptor potential ankyrin 1 (TRPA1) channels to evoke a pain response. In the DRG, neuro-immune cross talk following peripheral nerve injury is accomplished through the release of extracellular vesicles by neurons, which are engulfed by nearby macrophages. These vesicles deliver several determinants including microRNAs (miRs), with the potential to afford long-term alterations in macrophages that impact pain mechanisms. On one hand the delivery of neuron-derived miR-21 to macrophages for example, polarises these cells towards a pro-inflammatory/pro-nociceptive phenotype; on the other hand, silencing miR-21 expression in sensory neurons prevents both development of neuropathic allodynia and recruitment of macrophages in the DRG. Immune system mechanisms in the central nervous system In the dorsal horn of the spinal cord, growing evidence over the last two decades has delineated signalling pathways that mediate neuron-microglia communication such as P2X4/BDNF/GABAA, P2X7/Cathepsin S/Fractalkine/CX3CR1, and CSF-1/CSF-1R/DAP12 pathway-dependent mechanisms. Conclusions and implications Definition of the modalities by which neuron and immune cells communicate at different locations of the pain pathway under neuropathic pain states constitutes innovative biology that takes the pain field in a different direction and provides opportunities for novel approaches for the treatment of chronic pain.