Magnetic Resonance Neurography: Improved Diagnosis of Peripheral Neuropathies

Peripheral neuropathies account for the most frequent disorders seen by neurologists, and causes are manifold. The traditional diagnostic gold-standard consists of clinical neurologic examinations supplemented by nerve conduction studies. Due to well-known limitations of standard diagnostics and atypical clinical presentations, establishing the correct diagnosis can be challenging but is critical for appropriate therapies. Magnetic resonance neurography (MRN) is a relatively novel technique that was developed for the high-resolution imaging of the peripheral nervous system. In focal neuropathies, whether traumatic or due to nerve entrapment, MRN has improved the diagnostic accuracy by directly visualizing underlying nerve lesions and providing information on the exact lesion localization, extension, and spatial distribution, thereby assisting surgical planning. Notably, the differentiation between distally located, complete cross-sectional nerve lesions, and more proximally located lesions involving only certain fascicles within a nerve can hold difficulties that MRN can overcome, when basic technical requirements to achieve sufficient spatial resolution are implemented. Typical MRN-specific pitfalls are essential to understand in order to prevent overdiagnosing neuropathies. Heavily T2-weighted sequences with fat saturation are the most established sequences for MRN. Newer techniques, such as T2-relaxometry, magnetization transfer contrast imaging, and diffusion tensor imaging, allow the quantification of nerve lesions and have become increasingly important, especially when evaluating diffuse, non-focal neuropathies. Innovative studies in hereditary, metabolic or inflammatory polyneuropathies, and motor neuron diseases have contributed to a better understanding of the underlying pathomechanism. New imaging biomarkers might be used for an earlier diagnosis and monitoring of structural nerve injury under causative treatments in the future.

Beyond the Knife—Reviewing the Interplay of Psychosocial Factors and Peripheral Nerve Lesions

Peripheral nerve injuries are a common clinical problem. They not only affect the physical capabilities of the injured person due to loss of motor or sensory function but also have a significant impact on psychosocial aspects of life. The aim of this work is to review the interplay of psychosocial factors and peripheral nerve lesions. By reviewing the published literature, we identified several factors to be heavily influenced by peripheral nerve lesions. In addition to psychological factors like pain, depression, catastrophizing and stress, social factors like employment status and worker’s compensation status could be identified to be influenced by peripheral nerve lesions as well as serving as predictors of functional outcome themselves, respectively. This work sheds a light not only on the impact of peripheral nerve lesions on psychosocial aspects of life, but also on the prognostic values of these factors of functional outcome. Interdisciplinary, individualized treatment of patients is required to identify patient at risk for adverse outcomes and provide them with emotional support when adapting to their new life situation.

Long-term Follow-up and Histological Correlation of Peripheral Nervous System Alterations in Neurofibromatosis Type 2

Purpose To examine long-term alterations of the dorsal root ganglia (DRG) and the peripheral nerve in patients with neurofibromatosis type 2 (NF2) by in vivo high-resolution magnetic resonance neurography (MRN) and their correlation to histology. Methods In this prospective study the lumbosacral DRG, the right sciatic, tibial, and peroneal nerves were examined in 6 patients diagnosed with NF2 and associated polyneuropathy (PNP) by a standardized MRN protocol at 3 T. Volumes of DRG L3–S2 as well as peripheral nerve lesions were assessed and compared to follow-up examinations after 14–100 months. In one patient, imaging findings were further correlated to histology. Results Follow-up MRN examination showed a non-significant increase of volume for the DRG L3: +0.41% (p = 0.10), L4: +22.41% (p = 0.23), L5: +3.38% (p = 0.09), S1: +10.63% (p = 0.05) and S2: +1.17% (p = 0.57). Likewise, peripheral nerve lesions were not significantly increased regarding size (2.18 mm2 vs. 2.15 mm2, p = 0.89) and number (9.00 vs. 9.33, p = 0.36). Histological analyses identified schwannomas as the major correlate of both DRG hyperplasia and peripheral nerve lesions. For peripheral nerve microlesions additionally clusters of onion-bulb formations were identified. Conclusion Peripheral nervous system alterations seem to be constant or show only a minor increase in adult NF2. Thus, symptoms of PNP may not primarily attributed to the initial schwannoma growth but to secondary long-term processes, with symptoms only occurring if a certain threshold is exceeded. Histology identified grouped areas of Schwann cell proliferations as the correlate of DRG hyperplasia, while for peripheral nerve lesions different patterns could be found.

Secondary radial neuropathy after closed intramedullary nailing of humeral shaft fractures. Results over a 10-year period

Background. Retrospective study to examine secondary radial nerve palsy after humeral shaft fixation with closed locked intramedullary nailing. Materials and methods. Patients were identified from the hospitals’ registration systems for humeral shaft fractures, nerve lesions, plating, nailing and external fixation during a 10-year period from January 2007 to December 2016. All radial nerve lesions were registered and followed-up in patient files. Results. 89 patients with locked intramedullary nailing were available for an outpatient follow-up. Mean age was 67 years at the time of injury. 72 fractures were non-pathological. Of these, 31 were nonunions. 28, 61 and zero were identified in the proximal, middle and distal thirds of the humeral shaft respectively. 76 procedures were closed and 13 were with open reduction. Six radial nerves had nerve exploration. Eight patients developed immediate postoperative radial nerve palsies. Of these, six developed after closed surgery, two after nerve exploration. Of seven available patients with a radial nerve palsy, six of these remitted. Two patients were later surgically explored. One patient out of 89 sustained a verifiable permanent radial nerve paralysis. Conclusions. In this study, the risk of a radial nerve palsy was 7.9 % with closed locked intramedullary nailing. This study suggests that exploration of the radial nerve is not necessary routinely in order to prevent radial nerve lesions when performing closed intramedullary nailing for humeral shaft fractures in adults with a preoperative normal radial nerve function. Level of Evidence : Level IV.

Impact of 18F-FDG PET/CT in Predicting Recurrence in Neurolymphomatosis

To clarify the prognostic value of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) in Neurolymphomatosis (NL), we retrospectively reviewed medical records of all NL patients who had undergone 18F-FDG PET/CT from 2007 to 2020 at Kameda Medical Center and Tokyo Medical and Dental University Hospital. The clinical data of patients were compared with 18F-FDG PET/CT findings of number of nerve lesions and presence of non-nerve extranodal lesions (ENL). Subsequently, we calculated recurrence-free survival (RFS) and overall survival (OS) using the Kaplan–Meier method. A total of 28 patients (mean age 70.1 years, range 44–87 years; 15 women) were included in the study and 7 patients (25.0%) relapsed NL. The number of nerve lesions detected by 18F-FDG PET/CT ranged from 1 to 5, with an average of 2.02. ENL was observed in 18 cases (64.3%). The comparison between the findings revealed that the more the lesions detected by 18F-FDG PET/CT, the higher the probability of recurrence (χ2 = 13.651, p = 0.0085) and there was significantly shorter RFS for the patients with 3 or more nerve lesions (p = 0.0059), whereas the presence of ENL was not significantly associated with any clinical findings. The present study revealed that the more nerve lesions detected by 18F-FDG PET/CT, the poorer the recurrence rate and RFS.

Management of Post-Facelift Facial Paralysis With Botulinum Toxin Type A

Background Facial nerve injury after facelift is rare; hence, its treatment is poorly established. Botulinum toxin type A (BTXA) can be used to resolve the asymmetry. There is no protocol in the literature about the best timing for this treatment, injection sites or recommended dose. Objectives Propose a protocol to guide the management of asymmetries post-facelifts. Methods Fifteen patients with post-rhytidectomy facial palsies were treated in the non-paralyzed side with BTXA. After analysis of the smile deviation vectors, it is possible to identify the muscles that should be treated. The dose varied from 1-2 Uv/point. Patients were examined after 15 days for outcomes evaluation, and “touch-up” if needed. Patients were re-treated after 5-6 months in case of asymmetry recurrence. Results Symmetry was achieved in all cases. Six patients had definitive nerve lesions and needed to be treated every 6 months after the first session. Five patients had lesions affecting the upper third of the face, four of them were definitive nerve lesions. Two of the four patients who were treated less than 2 weeks after surgery recovered early from the post-facelift paralysis and developed reversed asymmetry due to the BTXA. In seven patients, the post-facelift asymmetry was due to neuropraxis: the recovery from the nerve injury and BTXA treatment occurred symmetrically on both sides of the face in the following months, after one single session. Conclusions Asymmetries post-facelifts were successfully managed with the proposed protocol. Best time for injection was 2-4 weeks after surgery.