[Rare nerve compression neuropathies] / Seltene Nervenkompressionssyndrome.

UNCOMMON NERVE COMPRESSION SYNDROMES: In regard to the complex anatomical relationship of peripheral nerves and muscles, tendons, fasciae as well as their long course within those anatomical structures and additional close contact to bony structures, they are prone to suffer from local compression syndromes. Hence creating a vast majority of entrapment syndromes - well described in literature for almost every single nerve. The purpose of this article is to give an overview of symptoms, signs, diagnostic studies and treatment options, addressing especially the less known syndromes. Compression syndromes of the upper arm and shoulder region include the suprascapular nerve syndrome the compression of the axillary nerve within the spatium quadrilaterale and the compression of the long thoracic nerve at the chest wall. The upper extremity offers a variety of infrequent entrapment syndromes, as the pronator teres syndrome and anterior interosseus syndrome, both resulting from pressure to the median nerve in the forearm. Compression neuropathy in the course of the radial nerve in the distal upper extremity is also known as supinator syndrome. Guyon's canal syndrome is the ulnar side equivalent to the well-known carpal tunnel syndrome. In the case of a Cheiralgia paresthetica, a compression of a sensory branch of the superficial radial nerve can be seen. In the lower extremities, a variety of nerves especially in the groin and thigh area can be compressed as they pass through the narrow spaces between the abdominal muscles or underneath the inguinal ligament. Compression of the lateral femoral cutaneous nerve is the most common syndrome. Compression syndromes of the femoral and obturator nerves are most often iatrogenic. Pain around the knee, especially the lateral part and following orthopedic procedures of the knee, can arise from a compression or a lesion of a small infrapatellar branch of the saphenous nerve. Another probably underdiagnosed syndrome is piriformis syndrome, resulting from an entrapment of the sciatic nerve as it passes through certain muscular structures. In the distal lower extremity, the peroneal and tibial nerves can be compressed at multple sites, clinically known as peroneal nerve paralysis resulting from nerve compression around the fibular head, the anterior and posterior tarsal tunnel syndrome, and Morton's metatarsalgia.

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.

Nerve Ultrasound Distinguishes Non-Inflammatory Axonal Polyneuropathy From Inflammatory Polyneuropathy With Secondary Axonal Damage.

INTRODUCTION: Chronic inflammatory demyelinating polyneuropathy (CIDP) may have a similar clinical and electrophysiological presentation to non-inflammatory axonal polyneuropathies (NIAPs) when secondary axonal damage occurs. We aimed to investigate if nerve ultrasound can help to differentiate CIDP with additional secondary axonal damage from NIAP. METHODS: In a retrospective analysis, the cross-sectional area (CSA) of the peripheral nerves measured by ultrasound at six suitable nerve sites was compared in 95 patients with CIDP and 82 patients with NIAP. We developed the adjusted Bochum ultrasound score (aBUS) ranging from 0 to 6 resulting from the number of sites with enlarged CSA (median, ulnar, radial, and sural nerve). RESULTS: The mean CSA of patients with CIDP was enlarged at all six nerve sites compared with the mean CSA of patients with NIAP. A total of 21 patients with CIDP did not meet 2010 electrophysiological diagnostic criteria (European Academy of Neurology/Peripheral Nerve Society Guideline, EFNS/PNS criteria) for CIDP at examination timepoint but only in further follow-up, while 25 patients with NIAP fulfilled electrophysiological EFNS/PNS criteria for CIDP as "possible" or "probable" CIDP. To increase diagnostic power, we included aBUS measured by ultrasound in patients classified as "possible" or "probable" resulting in an improved specificity of 94% and a sensitivity of 59%, compared to a specificity of the EFNS/PNS criteria alone of 60% and sensitivity of 78%. CONCLUSION: Using nerve ultrasound and the aBUS as a complementary method to distinguish CIDP from NIAP in case of secondary axonal damage can facilitate the diagnosis of CIDP.

Posterolateral myelotomy for intramedullary spinal cord tumors: the other way to do it?

BACKGROUND AND PURPOSE: To evaluate posterolateral myelotomy (PLM) as a surgical method for all cases of intramedullary spinal cord tumors (IMSCT) by assessing the surgical and functional outcomes of patients treated in our clinic. MATERIALS AND METHODS: Patients with IMSCT who underwent surgery using PLM from 2013 to 2018 were reviewed retrospectively. Objective and quantitative assessment of the preoperative, postoperative, and follow-up neurological status was performed by using the modified McCormick functional schema and sensory pain scale. RESULTS: A total of 33 operations were performed on 27 patients who met the inclusion criteria. The mean grade on the McCormick functional schema increased insignificantly from 2.0 preoperatively to 2.3 immediately postoperatively and decreased back to 2.1 at the follow-up examination. Just one patient exhibited a transient proprioception deficit. Significant pain relief was observed as expressed in an improvement of mean grade on the sensory pain scale. Only in two cases was late neuropathic pain reported. A gross total resection/subtotal resection (GTR/STR) was achieved in all cases of hemangioblastoma and cavernoma, while for the majority of astrocytomas, only partial removal was accomplished. For ependymoma, which represents the most common IMSCT, a GTR/STR was realized in 12 cases (86%). A statistically significant difference (p = 0.027) was found when comparing the extent of tumor resection (EOR) between the two most common IMSCT, i.e., ependymoma and astrocytoma. CONCLUSION: PLM may be considered a reliable surgical method for IMSCT, as it combines a satisfactory EOR with reduced risk of tissue damage and excellent pain relief.

Comparison between optical coherence tomography imaging and histological sections of peripheral nerves.

OBJECTIVE: Optical coherence tomography (OCT) is an imaging technique that uses the light-backscattering properties of different tissue types to generate an image. In an earlier feasibility study the authors showed that it can be applied to visualize human peripheral nerves. As a follow-up, this paper focuses on the interpretation of the images obtained. METHODS: Ten different short peripheral nerve specimens were retained following surgery. In a first step they were examined by OCT during, or directly after, surgery. In a second step the nerve specimens were subjected to histological examination. Various steps of image processing were applied to the OCT raw data acquired. The improved OCT images were compared with the sections stained by H & E. The authors assigned the structures in the images to the various nerve components including perineurium, fascicles, and intrafascicular microstructures. RESULTS: The results show that OCT is able to resolve the myelinated axons. A weighted averaging filter helps in identifying the borders of structural features and reduces artifacts at the same time. Tissue-remodeling processes due to injury (perineural fibrosis or neuroma) led to more homogeneous light backscattering. Anterograde axonal degeneration due to sharp injury led to a loss of visible axons and to an increase of light-backscattering tissue as well. However, the depth of light penetration is too small to allow generation of a complete picture of the nerve. CONCLUSIONS: OCT is the first in vivo imaging technique that is able to resolve a nerve's structures down to the level of myelinated axons. It can yield information about focal and segmental pathologies.

The Interdisciplinary Management of Foot Drop.

BACKGROUND: Foot drop can be caused by a variety of diseases and injuries. Although it is a common condition, its overall incidence has not been reported to date. Foot drop markedly restricts the everyday activities of persons suffering from it. There is, therefore, a need for an optimized strategy for its diagnosis and treatment that would be standardized across the medical specialties encountering patients with this problem. METHODS: This article consists of a review on the basis of pertinent publications re- trieved by a search in the Pubmed/MEDLINE and Cochrane databases, as well as a description of the authors' proposed strategy for the diagnosis and treatment of foot drop. RESULTS: Foot drop can be due to a disturbance at any central or peripheral location along the motor neural pathway that terminates in the dorsiflexor muscles of the foot, or at multiple locations in series. Optimal localization of the lesion(s) is a pre- requisite for appropriate treatment and a successful outcome. The most common causes are L5 radiculopathy and peroneal nerve injury. An operation by a neuro- surgeon or spinal surgeon is a reasonable option whenever there is a realistic chance that the nerve will recover. In our opinion, any patient with a subjectively disturbing foot drop and a clinically suspected compressive neuropathy of the peroneal nerve should be informed about the option of surgical decompression of the nerve at the fibular head, which can be performed with little risk. In case of a permanent foot drop, some patients can benefit from muscle-transfer surgery. For spastic foot drop, the option of botulinum toxin injections should be evaluated. CONCLUSION: The care of patients with foot drop could be optimized by interdisciplin- ary foot-drop clinics involving all of the relevant specialists. The goals of treatment should always be improved mobility in everyday life and the prevention of falls, pain, and abnormal postures.

Experimental investigations of a manually versus an electrically driven skull drill for bedside usage.

BACKGROUND: Manual skull drilling is an old but in modern neurosurgery still established procedure which can be applied quickly and universally in emergency situations. Electrical drilling requires more complex equipment and is usually reserved to the Operating Room (OR). It also seems desirable to apply an electrical drill for bedside usage but a suitable product does not exist so far. METHOD: Our experimental study using a manually and an electrically driven skull drill included a total of 40 holes drilled into synthetic biomechanical sheets. Half of the holes were produced with a prototype electrical drilling machine of the company Kaiser Technology and half of them with a traditional manual drill. Different drilling parameters such as the geometry of the borehole, the drilling forces and the drilling vibrations were captured during all experiments. RESULTS: The electrical drilling needed higher vertical force by the operators and a longer time to penetrate the sheet. A reason was the relatively lower rotational speed provided by this particular drill. When drilling electrically the vibrations were substantially less which in turn led to a more precise shape of the holes (revealed by observation via a microscope). CONCLUSIONS: The electrification of bedside drilling can in principle enable emergency craniostomies to be performed with greater ease and accuracy. The power of the electric drive, however, must be at least equivalent to the power of the traditional manual drill. Otherwise, the vertical forces exerted on the scull by the operator become inhibitive. The challenge is to combine cost-efficiency and re-sterilizability of an electrically driven drilling machine which at the same time is small and simple enough to qualify for emergency applications.

High-resolution in vivo imaging of peripheral nerves using optical coherence tomography: a feasibility study.

OBJECTIVE: Because of their complex topography, long courses, and small diameters, peripheral nerves are challenging structures for radiological diagnostics. However, imaging techniques in the area of peripheral nerve diseases have undergone unexpected development in recent decades. They include MRI and high-resolution sonography (HRS). Yet none of those imaging techniques reaches a resolution comparable to that of histological sections. Fascicles are the smallest discernable structure. Optical coherence tomography (OCT) is the first imaging technique that is able to depict a nerve's ultrastructure at micrometer resolution. In the current study, the authors present an in vivo assessment of human peripheral nerves using OCT. METHODS: OCT measurement was performed in 34 patients with different peripheral nerve pathologies, i.e., nerve compression syndromes. The nerves were examined during surgery after their exposure. Only the sural nerve was twice examined ex vivo. The Thorlabs OCT systems Callisto and Ganymede were used. For intraoperative use, a hand probe was covered with a sterile foil. Different postprocessing imaging techniques were applied and evaluated. In order to highlight certain structures, five texture parameters based on gray-level co-occurrence matrices were calculated according to Haralick. RESULTS: The intraoperative use of OCT is easy and intuitive. Image artifacts are mainly caused by motion and the sterile foil. If the artifacts are kept at a low level, the hyporeflecting bundles of nerve fascicles and their inner parts can be displayed. In the Haralick evaluation, the second angular moment is most suitable to depict the connective tissue. CONCLUSIONS: OCT is a new imaging technique that has shown promise in peripheral nerve surgery for particular questions. Its resolution exceeds that provided by recent radiological possibilities such as MRI and HRS. Since its field of view is relatively small, faster acquisition times would be highly desirable and have already been demonstrated by other groups. Currently, the method resembles an optical biopsy and can be a supplement to intraoperative sonography, giving high-resolution insight into a suspect area that has been located by sonography in advance.

Rare finding in peripheral nerve surgery: an unicentric Castleman disease presenting as median nerve tumour.

A 51 year old man presented with progressive swelling in the upper arm. MRI revealed a solitary mass extending from the median nerve. Intraoperative finding was a tumour extending within the nerve in its proximal fibres. The histological result showed a Castleman disease.

Complications associated with cervical vertebral body replacement with expandable titanium cages.

Our aim was to analyze complications and risk factors for cervical vertebral body replacement (VBR) with expandable titanium cages (ETC). Fifty patients; 22 women and 28 men, mean age 61years, undergoing cervical VBR from 2010 to 2015 were analyzed. Complications were stratified by hardware-association (HA). Univariate and multivariate logistic regression was used to identify independent risk factors. Single, two and three level corpectomies were performed in 32, 15 and 3 patients respectively. A circumferential approach was necessary in 16 cases. At mean follow-up (7.3 months) 66% of patients had recovered. Radiological data showed a significant distraction (2.60mm, p<0.0001) and lordosis (5°, p=0.001). Twenty-three patients experienced 42 complications; 18 HA, 24 non-HA and 24% needed revision surgery. The number of corpectomy levels and surgical approach significantly correlated with the risk of complications (p=0.001), especially non-HA complications (p=0.002). On multivariate analysis, only the number of corpectomy levels (p<0.02, odds ratio 5.48, 95% CI 1.31-22.91) was a significant predictor of complications. We conclude that ETC are efficacious devices for cervical spine VBR, however, when used for more than 1 level, the corpectomy complication rate significantly increases.

Radiological and clinical results of patients after ACDF with and without preoperative software-assisted cage selection.

OBJECTIVE: Comparison of software facilitated preoperatively-selected cages versus standard intraoperatively-selected cages, assessing radiological and clinical outcomes of patients after single level cervical discectomy and fusion (ACDF). METHODS: Cages of study group patients were preoperatively chosen via software-aided dimensioning. Controls obtained cages determined by intraoperative trail implants. Primary endpoints were segmental height (SH), regional angulation (RA) and global cervical angulation (GCA) measured on plain radiographs before, immediately and 12 months after surgery. Neck pain on the visual analogue scale, the neck disability index, and patient satisfaction index recorded at 12 months follow up (FU) were the secondary endpoints. RESULTS: Each group comprised of 20 patients and both depicted similar demographics and operated segmental levels. Mean postoperative SH was significantly increased in both study and control groups, p<0.001* and p=0.006* respectively. Immediate postoperative gain of lordosis was only significant for the study group p<0.001*. At 12 months FU, SH and RA decreased significantly in both groups. GCA and all secondary endpoints were similar for various measured time points. The two groups did not show any significant difference for all investigated parameters. CONCLUSION: The radiographical and clinical outcomes of patients receiving cages preoperatively selected by software-assistance are similar to that of patients obtaining conventionally chosen cages. However the former allows for better regional gain/restoration of lordosis.

Sonographic examination of the median nerve in dialysis patients and after renal transplantation.

OBJECTIVE: Patients with renal insufficiency are predisposed to develop CTS (carpal tunnel syndrome). In particular, long-term dialysis seems to contribute to changes in median nerve texture which lead to an increased risk for CTS. The current study was designed to evaluate if these structural changes can be detected by HRS (high-resolution sonography). Additionally, the current study aimed to determine if changes are reversible after termination of dialysis. METHODS: Fifty patients (98 hands) were included in the study. The study population was subdivided into three groups: patients without any history of renal disease (H, n = 20), patients with long-term dialysis (D, n = 10), and patients after renal transplantation (TX, n = 20). None of the patients had any clinical symptoms for a median nerve compression syndrome. The CSA (cross-sectional area) of the median nerve was evaluated both 12 cm proximally of the carpal tunnel inlet and directly at the carpal tunnel inlet. The ratio of those two values, the WFR (wrist forearm ratio), was calculated and analyzed. RESULTS: The CSA demonstrated significantly higher values in dialysis (D) and transplanted (TX) patients compared to the healthy (H) control group (P < 0.001). No significant differences were detectable between the D and TX groups. Specifically, there was no significant difference in the WFR. CONCLUSION: Patients with chronic renal disease demonstrate significantly higher CSA values compared to their healthy counterparts. Termination of dialysis does not seem to reverse these morphological changes.

Clinical relevance of neuroforaminal patency after anterior cervical discectomy and fusion.

BACKGROUND: We sought to investigate the clinical relevance of neuroforaminal patency and facet degeneration one year after anterior cervical discectomy and fusion (ACDF). Previous studies were characterized by imprecise techniques and fragmentary measurements, and most lacked reliable clinical data and correlation analyses. METHODS: Patients with cervical mono- or bi-level degenerative pathology were prospectively included. Neuroforaminal size and segmental height were determined quantitatively, and the degree of facet degeneration was assessed qualitatively before and one year after the operation, by computed tomography. Clinical data, such as the severity of neck and arm pain, were assessed on a visual analogue scale (VAS) from 0 to 10, and neck disability index (NDI) was recorded before and one year after the operation. Their correlation with radiological data was investigated. RESULTS: Seventy-nine patients aged 53.3 ± 11.3 years were included. One year after surgery, median VAS pain intensity was still significantly improved (neck, from 5 to 1; right arm, from 2 to 1; left arm, from 4 to 1) as was NDI (from 40 to 20). Neuroforaminal size showed a reduction on both sides (left, 0.0289 ± 0.09 cm(2); right, 0.0149 ± 0.08 cm(2)). One year after the operation, segmental height decreased and facet degeneration increased from measures taken before the operation. No correlations were found between neuroforaminal stenosis or the degree of facet degeneration and various clinical outcome parameters. CONCLUSIONS: The decrease in segmental height one year after ACDF leads in turn to secondary neuroforaminal stenosis and progressive facet degeneration. Of the various neuroforaminal variables used, none revealed a threshold value indicative of the presence or severity of radicular arm pain. This absence of correlation between imaging and clinical information is important and should be considered when allocating patients for surgical interventions.

Objective assessment of aesthetic outcome after breast conserving therapy: subjective third party panel rating and objective BCCT.core software evaluation.

We analysed intra- and inter-rater agreement of subjective third party assessment and agreement with a semi-automated objective software evaluation tool (BCCT.core). We presented standardized photographs of 50 patients, taken shortly and one year after surgery to a panel of five breast surgeons, six breast nurses, seven members of a breast cancer support group, five medical and seven non-medical students. In two turns they rated aesthetic outcome on a four point scale. Moreover the same photographs were evaluated by the BCCT.core software. Intra-rater agreement in the panel members was moderate to substantial (k = 0.4-0.5; wk = 0.6-0.7; according to different subgroups and times of assessment). In contrast inter-rater agreement was only slight to fair (mk = 0.1-0.3). Agreement between the panel participants and the software was fair (wk = 0.24-0.45). Subjective third party assessment only fairly agree with objective BCCT.core evaluation just as third party participants do not agree well among each other.