["Nerve Surgery" In German-Speaking Countries - Starting With The Nerve Club Up To A Certificate]. / "Nervenchirurgie" im deutschsprachigen Raum ­ vom NervClub zum Zertifikat.

We present the Nerve Club, a community of colleagues originating from german-speaking countries and dedicated to those working in or outside surgery with interest in the peripheral nerve. This article reviews the club´s history and specific characteristics and activities, and highlights the concept of a certificate in nerve surgery. We have annual club meetings and organize every two years a plexus symposium. Also exists a scientific publication award and cooperation with an online based journal dedicated to medical publications in the field of nerve surgery.

[Functional Outcome of Peripheral Nerve Injury after Pediatric Supracondylar Humerus Fracture: Comparison of Surgical and Conservative Treatment]. / Funktionelle Ergebnisse peripherer Nervenverletzungen nach kindlichen suprakondylären Humerusfrakturen: Vergleich operativer und konservativer Behandlung.

Supracondylar humerus fractures are the most common elbow fractures in children up to 10 years of age. The incidence of associated nerve injuries varies up to 15% depending on the data. Traumatic and iatrogenic lesions mainly affect the ulnar nerve. The regeneration of peripheral nerves is comparatively better in childhood. In the present study, the functional results after surgical and conservative treatment of nerve injuries in children after supracondylar fractures were compared and analyzed for influencing factors. In this retrospective comparative study, clinical data of pediatric nerve injuries following supracondylar humerus fractures treated over a period of 13 years (2008-2021) were analyzed. Children who were treated surgically (neurolysis, autologous reconstruction) due to insufficient clinical/neurophysiological improvement within 6 months after trauma or who were followed up conservatively in case of regression of symptoms within 6 months after trauma were included. All patients underwent multidisciplinary follow-up. 48 patients (26 female/22 male) with nerve injuries were included in this study. All patients had a history of surgical treatment with K- wire fixation due to severe dislocated fractures. The mean age was 7±2 years. The initial symptoms were severe motor deficits in all patients and sensory deficits in 87.5% (n=42). Isolated lesions of the ulnar nerve were most common (n=24, 50%). The nerve was neurolysed in 21 patients and additionally transferred to the volar side in 15. Nerve grafting was performed in 7 children and split repair in 2. Postoperatively, there was a significant improvement in motor function in all patients. Despite comparably severe motor deficits at initial presentation, further 20 children were treated conservatively due to the regression of neurological deficits. They showed comparably good functional results. No serious complications were recorded in either group. The average follow-up time was 377.25±524.87 days. The presented study shows excellent functional results after surgical treatment of pediatric nerve injuries without severe complications. Children with comparatively high-grade lesions at initial presentation have a good chance of complete spontaneous remission even without surgery. For this reason, the indication for surgery in children should be very carefully considered.

[Rare Compression Syndrome of the Median Nerve due to a Supracondylar Humeral Process and a Ligament of Struthers]. / Seltenes Kompressionssyndrom des N. medianus durch den Processus supracondylaris und das Struthers-Ligament.

INTRODUCTION: A supracondylar process is a bony spur on the distal anteromedial surface of the humerus, and it is considered an anatomical variant with a prevalence of 0.4-2.7% according to anatomical studies. In almost all cases, it is associated with a fibrous, sometimes ossified ligament, which extends from the supracondylar process to the medial epicondyle. This ligament is known in the literature as the ligament of Struthers, named after the Scottish anatomist who first described it in detail in 1854. In rare cases, the supracondylar process can be a clinically relevant finding as a cause of nerve compression syndrome. The median and ulnar nerve can be trapped by the ring-shaped structure formed by the ligament of Struthers and the supracondylar process. CASE REPORT: A 59-year-old patient with symptoms of a cubital tunnel syndrome and additional ipsilateral sensory deficits in his thumb was referred to our clinic. Electroneurography showed no signs of an additional carpal tunnel syndrome. Preoperative x-ray and CT scans of the upper arm revealed a supracondylar process, which led us to suspect an associated entrapment of the median nerve. An MRI scan of the upper arm showed a ligament of Struthers and signs of a related median nerve compression as we initially assumed. We performed a surgical decompression of the median nerve in the distal upper arm and of the ulnar nerve in the cubital tunnel. Intraoperatively, there was evidence of compression of the median nerve due to the supracondylar process and the ligament of Struthers. The latter was cleaved and then resected along with the supracondylar process. Three months after surgery, the patient had no motor or sensory deficits. SUMMARY: The ring-shaped structure formed by the supracondylar process and ligament of Struthers represents a rare cause of compression syndrome of the median and ulnar nerve. Its incidence remains unknown so far. This anatomical variant should be considered a differential diagnosis in case of possibly related nerve entrapment symptoms after ruling out other, more frequent nerve compression causes. Moreover, the supracondylar process should be completely resected including the periosteum during surgery to minimise the risk of recurrence.

[Long-Term Outcomes after Surgery of the Neurogenic Thoracic-Outlet Syndrome in Adolescents]. / Langzeitergebnisse nach Operation des neurogenen Thoracic-Outlet-Syndroms bei Jugendlichen.

BACKGROUND: Neurogenic Thoracic Outlet Syndrome (nTOS) describes a complex of symptoms caused by the compression of neural structures at the upper thoracic outlet. Typical symptoms include pain, numbness and motor weakness of the affected extremity. The incidence of nTOS is 2-3 per 100,000 and is highest between the ages of 25 and 40. There are only a few studies evaluating the surgical outcomes of nTOS in adolescent patients. In particular, there is a lack of long-term data. MATERIALS AND METHODS: In a retrospective study of nTOS cases receiving surgical treatment in our clinic between 2002 and 2021, eight patients between 15 and 18 years of age were included. Demographic data, risk factors, clinical symptoms, clinical functional tests, neurophysiological, radiological and intraoperative findings were evaluated. Postoperative data were recorded using a standardised questionnaire. Decompression of the inferior truncus and the C8 and Th1 nerve roots was performed via a supraclavicular approach. RESULTS: The average duration of symptoms before surgery was two years. Of the eight patients who underwent surgery, six answered the written questionnaire and could be analysed for the study. The average follow-up was nine years (1-18 years). After surgery, all patients experienced pain reduction; three were pain-free in the long run and five no longer required pain medication. Strength improved in all patients, but two patients still had mild motor deficits. Sensory disturbances were reduced in all patients, but residual hypoesthesia persisted in five. With regard to overhead work, half of the patients had no impairment after surgery. All patients were able to work at the time of the survey. Half of the patients pursued their sports activities without impairment, while mild impairment was reported by the other half. CONCLUSION: nTOS in adolescents is a rare compression syndrome. Decompression of the lower parts of the brachial plexus using a supraclavicular approach without resection of the first rib is an adequate treatment. This retrospective study showed that a reduction in pain was achieved in all patients. In some patients, slight sensory and motor disturbances as well as a certain restriction in overhead work persisted. Patients were able to return to sports.

Mapping Motor Neuroplasticity after Successful Surgical Brachial Plexus Reconstruction Using Navigated Transcranial Magnetic Stimulation (nTMS).

Brachial plexus reconstruction (BPR) consists of the complex surgical restoration of nerve structures. To further understand the underlying motor cortex changes and evaluate neuroplasticity after a successful surgery, we performed a navigated transcranial magnetic stimulation (nTMS) study mapping the postoperative motor representation of the formerly plegic arm. We conducted a prospective nTMS study mapping the musculocutaneous nerve as a representative, prominent target of BPR including a patient (n = 8) and a control group (n = 10). Measurements like resting motor threshold (RMT), cortical motor area location, and size were taken. Mathematical analysis was performed using MATLAB 2022, statistical analysis was performed using SPSS 26, and nTMS mapping was performed using the Nexstim NBS 5.1 system. Mapping was feasible in seven out of eight patients. Median RMT on the affected hemisphere was 41% compared to 50% on the unaffected hemisphere and they were 37% and 36% on the left and right hemispheres of the control group. The motor area location showed a relocation of bicep brachii representation at the middle precentral gyrus of the corresponding contralateral hemisphere. Motor area size was increased compared to the control group and the patient's unaffected, ipsilateral hemisphere. Understanding cortical reorganization is important for potential future treatments like therapeutic nTMS. The issue of motor neuroplasticity in patients with brachial plexus lesions is worth exploring in further studies.

[Neuralgic amyotrophy: an inflammatory neuropathy and its surgical treatment]. / Neuralgische Amyotrophie ­ eine entzündliche Neuropathie und ihre operative Behandlung.

BACKGROUND: Neuralgic amyotrophy (NA) is a monofocal or oligofocal inflammatory neuropathy whose incidence has been significantly underestimated. A connection between constrictions and torsions of peripheral nerves with this disease has been increasingly established in recent years. Modern imaging techniques such as high-resolution nerve ultrasound and MR neurography have contributed to a better understanding of the pathophysiology and a better assessment of the prognosis of the disease. This has led to the concept of treating patients with such focal changes surgically in order to improve the prognosis. This review presents current ideas on the pathophysiology, clinical presentation, diagnosis and treatment of the disease. PATIENTS AND METHODS: In a retrospective study, pre-, intra- and postoperative findings of 22 patients with 23 constrictions/torsions of peripheral nerves of the upper extremity were analysed. The patients underwent surgery at a nerve surgery centre over a period of 3.5 years (Dec. 2019-May 2023). The median nerve was most frequently affected (N=9), followed by the suprascapular nerve (N=6) and radial nerve (N=4). The axillary nerve (N=3) and the accessory nerve (N=1) were also involved. Surgical exploration revealed nerve torsions (N=9), nerve constrictions (N=5), fascicular torsions (N=12) and fascicular constrictions (N=9). Depending on the intraoperative findings, epineuriotomies (N=1), epi- and perineuriotomies (N=33), end-to-end sutures (N=2), and one epi- and one perineural suture were performed. RESULTS: After an average follow-up of 10 months (3-28 months), 17 patients were re-examined. All of them reported a clear subjective improvement in motor deficits. Clinically and electromyographically, a reinnervation and significant increase in strength from a pre-existing strength grade of M0 to at least M3 in the vast majority of affected muscles was demonstrated in these patients. SUMMARY: The incidence of NA continues to be underestimated and, in a significant proportion of patients, leads to permanent motor deficits, most likely due to constrictions and torsions of affected nerves. Surgical treatment is recommended as early as possible. Very good results can usually be achieved with epi- and perineuriotomy. In rare cases, end-to-end neurorrhaphy or nerve grafting is required.

The impact of SARS-Covid-19 pandemic on peripheral nerve surgery - A single centre report.

OBJECTIVE: SARS-Cov-19 pandemic totally changed daily routine work in German hospitals. As hospital capacity was reduced, many surgeries were postponed or even cancelled. On March 25th 2020 the German Society of Neurosurgery (DGNC) published a statement in which urgent non-elective surgeries were defined for each neurosurgical domain, whereas elective interventions were deferred. The present work examines the impact of these Covid strategies focusing on patients with peripheral lesions who were conducted to our department during this period of time. METHODS: All patients who underwent any peripheral nerve surgery at our department from January 2018 until December 2022, were included. The complete range of surgeries including peripheral nerve lesions was examined encompassing compression syndromes, traumatic lesions of brachial plexus, traumatic lesions and tumors of single peripheral nerves. The numbers of surgical procedures were compared before, during and after pandemic. Pearson correlation coefficient was analysed. RESULTS: From 2018 to 2022 the total number of surgical procedures involving peripheral nerves included 2422 procedures. Compression syndromes made up the largest proportion (1433 operations, 59%), followed by peripheral nerve lesions (445 operations, 18%), peripheral nerve tumors (344 operations, 14%) and lesions of the brachial plexus (142 operations, 6%). The average was 40,5 interventions per month, the range was 7-63. Two declines in the number of peripheral nerve surgeries were noted during this period. The first was in April and May 2020 with an average drop of 65% and 41% respectively. In these months the average number of operations was 37. The second decrease was from October 2021 until January 2022, where number of surgeries was reduced by 16%, 36%, 83% and 18% with an average number of 50 operations. Both declines showed a significant and strong correlation with the lower number of compression syndrome treatments (r = 0.952, p < 0.001 and r = 0.968, p < 0.001), while no drop and no significant correlation was found in the treatment of traumatic peripheral nerve injuries (p = 0.769, r = 0.095 and p = 0.243, r = 0.366) and traumatic brachial plexus injuries (p = 0.787, r = 0.088 and p = 0.780, r = 0.09). A weak significant correlation was seen in the treatment numbers of peripheral nerve tumors (p = 0.017, r = 0.672 and p = 0.015, r = 0.67). CONCLUSION: Covid-19 pandemic lead to a significant decrease in the number of nerve decompressions, since, according to the German Society of Neurosurgery, those were considered as elective surgeries.

High-resolution ultrasound of the supra- and infraclavicular levels of the brachial plexus including the axillary nerve: imaging anatomy based on multiplanar reconstructions and technical guide.

PURPOSE: The diagnosis of peripheral nerve injuries remains challenging. Electromyography and nerve conduction studies do not allow precise localization of the lesion and differentiation between lesions in continuity and non-continuity in cases with complete axonotmesis. Improved ultrasound technology allows the examination of almost the entire peripheral nervous system. The complex sono-anatomy of the brachial plexus outside of the standard scanning planes makes it difficult to access this region. METHODS: On the basis of the Visible Human Project of the National Institutes of Health (NIH), multiplanar reconstructions were created with the 3D Slicer open-source software in the various planes of the ultrasound cross-sections. The ultrasound examination itself and the guidance of the ultrasound probe in relation to the patient were recorded as video files and were synchronized through the audio channel. Subsequently, image matching was performed. RESULTS: Multiplanar reconstructions facilitate visualization of anatomical regions which are challenging to access thereby enabling physicians to evaluate the course of the peripheral nerve of interest in dynamic conditions. Sonographically visible structures could be reproducibly identified in single-frame analysis. CONCLUSION: With precise knowledge of the ultrasound anatomy, the nerve structures of the brachial plexus can also be dynamically assessed almost in their entire course. An instructional video on ultrasound of the brachial plexus supplements this manuscript and has been published on Vimeo.com.

[Diagnostics and treatment of hourglass-like nerve constrictions and torsions in neuralgic amyotrophy]. / Diagnostik und Therapie sanduhrförmiger Nervenstrikturen und -torsionen bei neuralgischer Amyotrophie.

Neuralgic amyotrophy is a disease of the peripheral nervous system characterized by severe neuropathic pain followed by peripheral paralysis. A distinction is made between a hereditary and an idiopathic form, which is assumed to have an autoimmunological origin. Conservative medicinal treatment mainly consists of nonsteroidal anti-inflammatory drugs (NSAID), opioids and glucocorticoids; however, despite treatment, symptoms in the form of pain or paralysis persist in over 50% of cases. Inflammation can lead to strictures and torsions of peripheral nerves, which can be visualized by imaging using nerve sonography or magnetic resonance (MR) neurography and confirmed intraoperatively during surgical exploration. Based on the currently available data, patients with strictures and torsions of peripheral nerves can benefit from neurosurgical treatment.

Restoring musculocutaneous nerve function in 146 brachial plexus operations - A retrospective analysis.

INTRODUCTION: A brachial plexus lesion is a devastating injury often affecting young, male adults after traffic accidents. Therefore, surgical restoration of elbow flexion is critical for establishing antigravity movement of the upper extremity. We analyzed different methods for musculocutaneous reconstruction regarding outcome. METHODS: We conducted a retrospective analysis of 146 brachial plexus surgeries with musculocutaneous reconstruction performed at our department from 2013 to 2017. Demographic data, surgical method, donor and graft nerve characteristics, body mass index (BMI) as well as functional outcome of biceps muscle based on medical research council (MRC) strength grades before and after surgery were analyzed. Multivariate analysis was performed using SPSS. RESULTS: Oberlin reconstruction was the procedure performed most often (34.2%, n = 50). Nerve transfer and autologous repair showed no significant differences regarding outcome (p = 0.599, OR 0.644 CI95% 0.126-3.307). In case of nerve transfers, we found no significant difference whether reconstruction was performed with or without a nerve graft (e.g. sural nerve) (p = 0.277, OR 0.619 CI95% 0.261-1.469). Multivariate analysis identifies patient age as a strong predictor for outcome, univariate analysis indicates that nerve graft length > 15 cm and BMI of > 25 could lead to inferior outcome. When patients with early recovery (n = 19) are included into final evaluation after 24 months, the general success rate of reconstructions is 62,7% (52/83). CONCLUSION: Reconstruction of musculocutaneous nerve after brachial plexus injury results in a high rate of clinical improvement. Nerve transfer and autologous reconstruction both show similar results. Young age was confirmed as an independent predictor for better clinical outcome. Prospective multicenter studies are needed to further clarify.

Rationale and design of the peripheral nerve tumor registry: an observational cohort study.

AIM: Peripheral nerve tumors (PNT) are rare lesions. To date, no systematic multicenter studies on epidemiology, clinical symptoms, treatment strategies and outcomes, genetic and histopathologic features, as well as imaging characteristics of PNT were published. The main goal of our PNT Registry is the systematic multicenter investigation to improve our understanding of PNT and to assist future interventional studies in establishing hypotheses, determining potential endpoints, and assessing treatment efficacy. METHODS: Aims of the PNT registry were set at the 2015 Meeting of the Section of Peripheral Nerve Surgery of the German Society of Neurosurgery. A study protocol was developed by specialists in PNT care. A minimal data set on clinical status, treatment types and outcomes is reported by each participating center at initial contact with the patient and after 1 year, 2 years, and 5 years. Since the study is coordinated by the Charité Berlin, the PNR Registry was approved by the Charité ethics committee (EA4/058/17) and registered with the German Trials Registry (www.drks.de). On a national level, patient inclusion began in June 2016. The registry was rolled out across Europe at the 2019 meeting of the European Association of Neurosurgery in Dublin. RESULTS: Patient recruitment has been initiated at 10 centers throughout Europe and 14 additional centers are currently applying for local ethics approval. CONCLUSION: To date, the PNT registry has grown into an international study group with regular scientific and clinical exchange awaiting the first results of the retrospective study arm.

Thoracic Outlet Syndrome Part II: Consensus on the Management of Neurogenic Thoracic Outlet Syndrome by the European Association of Neurosurgical Societies' Section of Peripheral Nerve Surgery.

BACKGROUND: In the first part of this report, the European Association of Neurosurgical Societies' section of peripheral nerve surgery presented a systematic literature review and consensus statements on anatomy, classification, and diagnosis of thoracic outlet syndrome (TOS) along with a subclassification system of neurogenic TOS (nTOS). Because of the lack of level 1 evidence, especially regarding the management of nTOS, we now add a consensus statement on nTOS treatment among experienced neurosurgeons. OBJECTIVE: To document consensus and controversy on nTOS management, with emphasis on timing and types of surgical and nonsurgical nTOS treatment, and to support patient counseling and clinical decision-making within the neurosurgical community. METHODS: The literature available on PubMed/MEDLINE was systematically searched on February 13, 2021, and yielded 2853 results. Screening and classification of abstracts was performed. In an online meeting that was held on December 16, 2021, 14 recommendations on nTOS management were developed and refined in a group process according to the Delphi consensus method. RESULTS: Five RCTs reported on management strategies in nTOS. Three prospective observational studies present outcomes after therapeutic interventions. Fourteen statements on nonsurgical nTOS treatment, timing, and type of surgical therapy were developed. Within our expert group, the agreement rate was high with a mean of 97.8% (± 0.04) for each statement, ranging between 86.7% and 100%. CONCLUSION: Our work may help to improve clinical decision-making among the neurosurgical community and may guide nonspecialized or inexperienced neurosurgeons with initial patient management before patient referral to a specialized center.

Neurogenic Thoracic Outlet Syndrome.

BACKGROUND: Thoracic outlet syndrome (TOS) refers to a group of disorders in which there is compression of and/or damage to the neurovascular structures at the thoracic outlet, i.e., at the transition from chest to neck. The incidence of neurogenic thoracic outlet syndrome (nTOS) is estimated to be 2-3 / 100 000 / year, with an estimated prevalence of 10 / 100 000. Patients present with upper extremity sensorimotor symptoms that are often related to movement. The aim of the present article is to highlight the clinical presentation patterns of nTOS and to provide an overview of its diagnosis and treatment. METHODS: Selective literature search for prospective observational studies and RCTs, including systematic reviews and metaanalyses. RESULTS: There is no multicenter randomized controlled trial available on the treatment of nTOS. Prospective observational studies with a hierarchical study design report a positive effect of physiotherapy in 27-59% of cases. After unsuccessful conservative treatment, up to 56-90% benefit from surgical management. Patients with nTOS are more severely affected compared with those with other forms of TOS and benefit less from transaxillary first rib resection. nTOS patients who underwent supraclavicular decompression without rib resection had excellent surgical outcomes in 27%, good outcomes in 36%, acceptable outcomes in 26%, and poor surgical outcomes in 11% of cases. There is no systematic comparison available of the types of surgical management involved. Also, there is currently no uniform classification available for all medical sub-disciplines. Therefore, interpretation, and comparability of the study results are limited. CONCLUSION: Although nTOS is the most common form of TOS, studies on its treatment are currently limited in terms of numbers and quality. The type of surgical management varies according to the experience and preference of the surgeon, treating specialty, special anatomic features, and clinical symptoms.

Thoracic Outlet Syndrome Part I: Systematic Review of the Literature and Consensus on Anatomy, Diagnosis, and Classification of Thoracic Outlet Syndrome by the European Association of Neurosurgical Societies' Section of Peripheral Nerve Surgery.

BACKGROUND: Although numerous articles have been published not only on the classification of thoracic outlet syndrome (TOS) but also on diagnostic standards, timing, and type of surgical intervention, there still remains some controversy because of the lack of level 1 evidence. So far, attempts to generate uniform reporting standards have not yielded conclusive results. OBJECTIVE: To systematically review the body of evidence and reach a consensus among neurosurgeons experienced in TOS regarding anatomy, diagnosis, and classification. METHODS: A systematic literature search on PubMed/MEDLINE was performed on February 13, 2021, yielding 2853 results. Abstracts were screened and classified. Recommendations were developed in a meeting held online on February 10, 2021, and refined according to the Delphi consensus method. RESULTS: Six randomized controlled trials (on surgical, conservative, and injection therapies), 4 "guideline" articles (on imaging and reporting standards), 5 observational studies (on diagnostics, hierarchic designs of physiotherapy vs surgery, and quality of life outcomes), and 6 meta-analyses were identified. The European Association of Neurosurgical Societies' section of peripheral nerve surgery established 18 statements regarding anatomy, diagnosis, and classification of TOS with agreement levels of 98.4 % (±3.0). CONCLUSION: Because of the lack of level 1 evidence, consensus statements on anatomy, diagnosis, and classification of TOS from experts of the section of peripheral nerve surgery of the European Association of Neurosurgical Societies were developed with the Delphi method. Further work on reporting standards, prospective data collections, therapy, and long-term outcome is necessary.

Motoneuron-Specific PTEN Deletion in Mice Induces Neuronal Hypertrophy and Also Regeneration after Facial Nerve Injury.

In postmitotic neurons, several tumor suppressor genes (TSGs), including p53, Rb, and PTEN, modulate the axon regeneration success after injury. Particularly, PTEN inhibition is a key driver of successful CNS axon regeneration after optic nerve or spinal cord injury. In contrast, in peripheral neurons, TSG influence in neuronal morphology, physiology, and pathology has not been investigated to the same depth. In this study, we conditionally deleted PTEN from mouse facial motoneurons (Chat-Cre/PtenloxP/loxP ) and analyzed neuronal responses in vivo with or without peripheral facial nerve injury in male and female mice. In uninjured motoneurons, PTEN loss induced somatic, axonal, and nerve hypertrophy, synaptic terminal enlargement and reduction in physiological whisker movement. Despite these morphologic and physiological changes, PTEN deletion positively regulated facial nerve regeneration and recovery of whisker movement after nerve injury. Regenerating PTEN-deficient motoneurons upregulated P-CREB and a signaling pathway involving P-Akt, P-PRAS40, P-mTOR, and P-4EBP1. In aged mice (12 months), PTEN deletion induced hair loss and facial hyperplasia of the epidermis. This suggests a time window in younger mice with PTEN loss stimulating axon growth after injury, however, at the risk of hyperplasia formation at later time points in the old animal. Overall, our data highlight a dual TSG function with PTEN loss impairing physiological neuron function but furthermore underscoring the positive effects of PTEN ablation in axon regeneration also for the PNS.SIGNIFICANCE STATEMENT Tumor suppressor genes (TSGs) restrict cell proliferation and growth. TSG inhibition, including p53 and PTEN, stimulates axon regeneration after CNS injury. In contrast, in PNS axon regeneration, TSGs have not been analyzed in great depth. Herein we show enhanced peripheral axon regeneration after PTEN deletion from facial motoneurons. This invokes a signaling cascade with novel PTEN partners, including CREB and PRAS40. In adult mice, PTEN loss induces hyperplasia of the skin epidermis, suggesting detrimental consequences when reaching adulthood in contrast to a beneficial TSG role for regeneration in young adult mice. Thus, our data highlight the double-edged sword nature of interfering with TSG function.

Perineurioma: A Rare Entity of Peripheral Nerve Sheath Tumors.

OBJECTIVE: Intraneural perineurioma is a rare tumor entity. It is a benign, very slow growing peripheral nerve sheath tumor that typically occurs in children and young adults. Motor deficits and muscle atrophy are classic presenting symptoms, while sensory deficits are rare at the onset of the disease. Recommended treatment strategies are lacking. We have evaluated the clinical follow-up and our experience with treatment of this rare entity. METHODS: A total of 30 patients with intraneural perineuriomas were assessed retrospectively. Demographic data, clinical symptoms, diagnostic examinations, therapy strategies, and clinical outcome were analyzed. Descriptive statistical methods were used for evaluation. RESULTS: The mean age was 22 years. Eleven women and 19 men were affected. The lesion occurred in the area of the upper extremity in 16 patients and in the area of the lower extremity in 14 patients. The most frequently affected nerve was the sciatic nerve, followed by the radial nerve. All patients showed a motor deficit to some extent. Seventy percent (n = 21) revealed atrophy, 43.3% (n = 13) had sensitive deficits, and 17% (n = 5) suffered of pain. Fascicle biopsies were performed in 26 patients (87%). In four patients (13%), the tumor was completely resected and then reconstructed via nerve grafts. Seventy percent of the patients (n = 21) received a magnetic resonance imaging (MRI) within 5 years postoperatively, in which no progress was shown. CONCLUSIONS: To diagnose perineurioma, it is essential to take a biopsy of an enlarged, nonfunctional fascicle. Furthermore, a long-distance epineuriotomy to decompress the hypertrophic fascicle is reasonable. To preserve the nerves' residual function, a complete resection is not recommended. Results after grafting are poor. One reason for this might be residual tumor cells along the nerve that cannot be visualized. Malignant transformation is not yet reported and tumor growth is stable for years.

Prophylactic nimodipine treatment improves hearing outcome after vestibular schwannoma surgery in men: a subgroup analysis of a randomized multicenter phase III trial.

A 2016 published randomized multicenter phase III trial of prophylactic nimodipine treatment in vestibular schwannoma surgery showed only a tendency for higher hearing preservation rates in the treatment group. Gender was not included in statistical analysis at that time. A retrospective analysis of the trial considering gender, preoperative hearing, and nimodipine treatment was performed. The treatment group received parenteral nimodipine from the day before surgery until the seventh postoperative day. The control group was not treated prophylactically. Cochlear nerve function was determined by pure-tone audiometry with speech discrimination preoperatively, during in-patient care, and 1 year after surgery and classified according to the Gardner-Robertson grading scale (GR). Logistic regression analysis showed a statistically significant effect for higher hearing preservation rates (pre- and postoperative GR 1-4) in 40 men comparing the treatment (n = 21) and the control (n = 19) groups (p = 0.028), but not in 54 women comparing 27 women in both groups (p = 0.077). The results were also statistically significant for preservation of postoperative hearing with pre- and postoperative GR 1-3 (p = 0.024). There were no differences in tumor sizes between the treatment and the control groups in men, whereas statistically significant larger tumors were observed in the female treatment group compared with the female control group. Prophylactic nimodipine is safe, and an effect for hearing preservation in 40 men with preoperative hearing ability of GR 1-4 was shown in this retrospective investigation. The imbalance in tumor size with larger tumors in females of the treatment group may falsely suggest a gender-related effect. Further investigations are recommended to clarify whether gender has impact on nimodipine's efficacy.

Lipid metabolism adaptations are reduced in human compared to murine Schwann cells following injury.

Mammals differ in their regeneration potential after traumatic injury, which might be caused by species-specific regeneration programs. Here, we compared murine and human Schwann cell (SC) response to injury and developed an ex vivo injury model employing surgery-derived human sural nerves. Transcriptomic and lipid metabolism analysis of murine SCs following injury of sural nerves revealed down-regulation of lipogenic genes and regulator of lipid metabolism, including Pparg (peroxisome proliferator-activated receptor gamma) and S1P (sphingosine-1-phosphate). Human SCs failed to induce similar adaptations following ex vivo nerve injury. Pharmacological PPARg and S1P stimulation in mice resulted in up-regulation of lipid gene expression, suggesting a role in SCs switching towards a myelinating state. Altogether, our results suggest that murine SC switching towards a repair state is accompanied by transcriptome and lipidome adaptations, which are reduced in humans.

Sodium Fluorescein as Intraoperative Visualization Tool During Peripheral Nerve Biopsies.

OBJECTIVE: Owing to technical development of specific fluorophore filters, the neurosurgical application of sodium fluorescein (SF) has regained value in brain tumor surgery. The aim of this study was to determine the usefulness of SF during nerve biopsies. METHODS: This single-center study included 5 cases of nerve biopsies performed under microscope-based fluorescence with SF performed between March 2016 and February 2017. SF was applied intravenously (1 mg/kg body weight). After microsurgical dissection of the involved nerve segment, fluorescence-guided fascicular biopsy was performed. Selection of target fascicles was at the surgeon's discretion and took into account nerve stimulation for preservation of motor function and fluorescence intensity. Correlation to histopathologic examination was examined. Video analysis of intraoperative images comparing target fascicles with intense fluorescent response to adjacent fascicles of the same nerve segment was performed using ImageJ. RESULTS: All patients had motor or sensory deficits. Magnetic resonance imaging findings were similar, depicting long segments of gadolinium enhancement (minimum 11.7 cm). Each biopsy sample was positive resulting in diverse histopathologic results. Digital image analysis revealed a statistically significant difference of the complementary color green (P = 0.0473). CONCLUSIONS: Magnetic resonance imaging is the gold standard in diagnostic work-up of peripheral nerve disorders. Longitudinal nerve thickening with positive contrast enhancement is an unspecific magnetic resonance imaging finding. Various pathologies, such as tumors and inflammatory lesions, may cause this morphologic phenomenon. Nerve biopsies may be needed for diagnostic work-up. Intraoperative SF may help to depict the most affected fascicles and identify target fascicles for biopsy and increase diagnostic certainty of nerve biopsies.

Extra-foraminal Intraneural L5-S1 Disc Herniation Mimicking a Retroperitoneal Peripheral Nerve Sheath Tumour: Case Report and Review of the Literature.

Disc herniations can present with unusual findings at unusual locations, mimic different pathologies and create confusion in the daily practice. Extra-foraminal intraneural location of L5-S1 disc herniation is extremely rare and may not be noticed on initial imaging extending the time to reach the diagnosis. There is no specific imaging finding suggesting the intraneural location of the lesion. Here, we report a case of an extra-foraminal intraneural L5-S1 disc herniation mimicking a retroperitoneal peripheral nerve sheath tumour and review similar cases in the literature.