Individual Nerve Research Articles

Relationship between nerve ultrasonography image and electrophysiology in diabetic polyneuropathy.

This study aims to investigate the association between cross-sectional area (CSA) imaging findings of nerve ultrasound and conventional nerve conduction studies (NCS) for patients with distal symmetric sensorimotor polyneuropathy (DSPN) due to type 2 diabetes mellitus. We enrolled 103 patients with type 2 diabetes mellitus and collected their demographic data, modified Michigan Neuropathy Screening Instrument (mMNSI) score, NCS, and ultrasonography images of peripheral nerves. The relationship of ultrasound variables for individual nerves and the ultrasound pattern sum score (UPSS) to conventional NCS findings was investigated. A higher grade of DSPN was associated with a notably higher CSA. Multivariate step-wise regression analysis revealed that the number of abnormal nerves was a positive independent variable for UPSS (β coefficient = 0.4205; P < 0.0001). Of the five nerves studied, abnormalities of the tibial nerve (P ≤ 0.0100) and ulnar nerve (P = 0.052) were the most significant variables. The tibial nerve exhibited the most substantial association with elevated UPSS. In addition, a strong correlation was observed between abnormal NCS findings and UPSS in patients with DSPN.

Laterality, sexual dimorphism, and human vagal projectome heterogeneity shape neuromodulation to vagus nerve stimulation

Neuromodulation by vagus nerve stimulation (VNS) provides therapeutic benefits in multiple medical conditions, including epilepsy and clinical depression, but underlying mechanisms of action are not well understood. Cervical vagus nerve biopsies were procured from transplant organ donors for high resolution light microscopy (LM) and transmission electron microscopy (TEM) to map the human fascicular and sub-fascicular organization. Cervical vagal segments show laterality with right sided dominance in fascicle numbers and cross-sectional areas as well as sexual dimorphism with female dominance in fascicle numbers. The novel and unprecedented detection of numerous small fascicles by high resolution LM and TEM expand the known fascicle size range and morphological diversity of the human vagus nerve. Ground truth TEM quantification of all myelinated and unmyelinated axons within individual nerve fascicles show marked sub-fascicular heterogeneity of nerve fiber numbers, size, and myelination. A heuristic action potential interpreter (HAPI) tool predicts VNS-evoked compound nerve action potentials (CNAPs) generated by myelinated and unmyelinated nerve fibers and validates functional dissimilarity between fascicles. Our findings of laterality, sexual dimorphism, and an expanded range of fascicle size heterogeneity provide mechanistic insights into the varied therapeutic responses and off-target effects to VNS and may guide new refinement strategies for neuromodulation.

Exploring Structural and Molecular Features of Sciatic Nerve Lesions in Diabetic Neuropathy: Unveiling Pathogenic Pathways and Targets.

Lesioned fascicles (LF) in the sciatic nerves of individuals with diabetic neuropathy (DN) correlate with clinical symptom severity. This study aimed to characterize the structural and molecular composition of these lesions to better understand DN pathogenesis. Sciatic nerves from amputees with and without type 2 diabetes (T2D) were examined using ex vivo magnetic resonance neurography, in vitro imaging, and proteomic analysis. Lesions were only found in T2D donors and exhibited significant structural abnormalities, including axonal degeneration, demyelination, and impaired blood nerve barrier (BNB). While non-lesioned fascicles from T2D donors showed activation of neuroprotective pathways, lesioned fascicles lacked this response and instead displayed increased complement activation via the classical pathway. The detection of liver-derived acute-phase proteins suggests that BNB disruption facilitates harmful inter-organ communication between the liver and nerves. These findings reveal key molecular mechanisms contributing to DN and highlight potential targets for therapeutic intervention.

Top 10 Clinical Pearls in Vasculitic Neuropathies.

Vasculitic neuropathies are a diverse group of inflammatory polyneuropathies that result from systemic vasculitis (e.g., polyarteritis nodosa, granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, microscopic polyangiitis), vasculitis resulting from rheumatological disorders (e.g., rheumatoid arthritis and Sjögren's syndrome), paraneoplastic conditions, viruses, and medications. Occasionally, vasculitis is restricted to the peripheral nerves and termed nonsystemic vasculitic neuropathy. Presenting with an acute or subacute onset of painful sensory and motor deficits, ischemia to individual peripheral nerves results in the classic "mononeuritis multiplex" pattern. Over time, overlapping mononeuropathies will result in a symmetrical or asymmetrical sensorimotor axonal polyneuropathy. The diagnosis of vasculitic neuropathies relies on extensive laboratory testing, electrodiagnostic testing, and nerve and/or other tissue biopsy. Treatment consists primarily of immunosuppressant medications such as corticosteroids, cyclophosphamide, rituximab, methotrexate, or azathioprine, in addition to neuropathic pain treatments. Frequently, other specialists such as rheumatologists, pulmonologists, and nephrologists will comanage these complex patients with systemic vasculitis. Prompt recognition of these conditions is imperative, as delays in treatment may result in permanent deficits and even death.

A Case Report of Systemic Lupus Erythematosus Presenting as Isolated Mononeuropathy Multiplex.

Mononeuropathy multiplex is a pattern of progressive sensory and motor deficits in the distribution of two or more peripheral nerves. The differential for mononeuropathy multiplex includes vasculitis, autoimmune disorders, infectious diseases, sarcoidosis, amyloidosis, cryoglobulinemia, and paraneoplastic disease. We present a case of a 42-year-old woman with hypothyroidism who presented with 1week of ascending numbness and weakness, persistent fevers, and 3months of constant burning pain in both feet. Her neurologic exam was notable for asymmetric weakness, loss of sensation, and diminished reflexes of her lower extremities. Other than mild fever and tachycardia, there were no systemic exam findings. Her laboratory workup was significant for elevated inflammatory markers, positive ANA, anti-ribonucleoprotein, smooth muscle antibody, and lupus anticoagulant, high anti-dsDNA titers, and low complement levels. An MRI of her lumbar spine was negative for lumbosacral nerve root pathology. Cerebrospinal fluid studies demonstrated normal cell counts, glucose, and protein and no evidence of infection. An electromyography (EMG) and nerve conduction studies (NCS) demonstrated asymmetric involvement of multiple individual peripheral nerves. Given the patient's symptoms, asymmetric exam findings, laboratory results, and EMG/NCS findings, she was diagnosed with mononeuropathy multiplex secondary to systemic lupus erythematosus (SLE) and started on steroid and immunosuppressant therapy with symptomatic improvement. Overall, this case illustrates the unique presentation of mononeuropathy multiplex as the initial manifestation of SLE. The identification of this specific type of neuropathy may play a crucial role in the prompt diagnosis of SLE and timely initiation of treatment, preventing further complications of the disease.

Bioelectronic Medicines-A Novel Approach of Therapeutics in Current Epoch.

Bioelectronic medicines aim to diagnose and treat a wide range of illnesses and ailments, including cancer, rheumatoid arthritis, inflammatory bowel disease, obesity, diabetes, asthma, paralysis, blindness, bleeding, ischemia, organ transplantation, cardiovascular disease, and neurodegenerative diseases. The focus of bioelectronic medicine is on electrical signaling of the nervous system. Understanding the nervous system's regulatory roles and developing technologies that record, activate, or inhibit neural signaling to influence particular biological pathways. Bioelectronic medicine is an emerging therapeutic option with the interconnection between molecular medicine, neuroscience, and bioengineering. The creation of nerve stimulating devices that communicate with both the central and peripheral nervous systems has the potential to completely transform how we treat disorders. Although early clinical applications have been largely effective across entire nerves, the ultimate goal is to create implantable, miniature closed-loop systems that can precisely identify and modulate individual nerve fibers to treat a wide range of disorders. The data bases such as PubMed, and Clinicaltrial.gov.in were searched for scientific research, review and clinical trials on bioelectronic medicine. The field of bioelectronic medicine is trending at present. In recent years, researchers have extended the field's applications, undertaken promising clinical trials, and begun delivering therapies to patients, thus creating the groundwork for significant future advancements. Countries and organizations must collaborate across industries and regions to establish an atmosphere and guidelines that foster the advancement of the field and the fulfillment of its prospective advantages.

Magnetic resonance neurography in the diagnosis of neurological subtypes of thoracic outlet syndrome.

Neurological thoracic outlet syndrome (TOS) can be challenging to diagnose, particularly given its described subtypes of neurogenic TOS (NTOS) and disputed TOS (DTOS) that exhibit variable clinical presentations and etiologies. The diagnostic workup of TOS often includes magnetic resonance neurography (MRN) of the brachial plexus. Specific MRN imaging modifications for TOS evaluation are required to maximize spatial and contrast resolution to increase the conspicuity of nerve segments and their relationships to surrounding osseous structures. Dynamic assessment with arm positioning is used to evaluate outlet narrowing and compression of the plexus. Individual nerve segments are interrogated for their longitudinal and cross-sectional morphologies and signal characteristics. In patients with NTOS, MRN may reveal focal impingement of the C8/T1 nerve roots and/or lower trunk with accompanying abnormal T2-weighted signal hyperintensity. Predisposing anatomical entities include cervical ribs, rib synostoses, hypertrophic callous following clavicular fracture, remnant first thoracic rib from prior incomplete resection, and variable perineural scarring. In comparison, DTOS patients frequently demonstrate signal hyperintensity and enlargement of the mid plexus (trunk and division level), with narrowing of the costoclavicular interval. Following comprehensive diagnostic workup that frequently includes electrodiagnostic testing, patients are directed to different management pathways. Nonsurgical management is considered for all cases of DTOS; all patients with NTOS or DTOS who fail conservative treatment warrant referral for a surgical opinion. If surgery is pursued, MRN can be helpful in preoperative planning.

Greater exposure to PM2.5 and PM10 was associated with lower corneal nerve measures: the Maastricht study - a cross-sectional study

BackgroundEpidemiological and toxicological studies indicate that increased exposure to air pollutants can lead to neurodegenerative diseases. To further confirm this relationship, we evaluated the association between exposure to ambient air pollutants and corneal nerve measures as a surrogate for neurodegeneration, using corneal confocal microscopy.MethodsWe used population-based observational cross-sectional data from The Maastricht Study including N = 3635 participants (mean age 59.3 years, 51.6% were women, and 19.9% had type 2 diabetes) living in the Maastricht area. Using the Geoscience and hEalth Cohort COnsortium (GECCO) data we linked the yearly average exposure levels of ambient air pollutants at home address-level [particulate matter with diameters of ≤ 2.5 µm (PM2.5), and ≤ 10.0 µm (PM10), nitrogen dioxide (NO2), and elemental carbon (EC)]. We used linear regression analysis to study the associations between Z-score for ambient air pollutants concentrations (PM2.5, PM10, NO2, and EC) and Z-score for individual corneal nerve measures (corneal nerve bifurcation density, corneal nerve density, corneal nerve length, and fractal dimension).ResultsAfter adjustment for potential confounders (age, sex, level of education, glucose metabolism status, corneal confocal microscopy lag time, inclusion year of participants, smoking status, and alcohol consumption), higher Z-scores for PM2.5 and PM10 were associated with lower Z-scores for corneal nerve bifurcation density, nerve density, nerve length, and nerve fractal dimension [stβ (95% CI): PM2.5 -0.10 (-0.14; -0.05), -0.04 (-0.09; 0.01), -0.11 (-0.16; -0.06), -0.20 (-0.24; -0.15); and PM10 -0.08 (-0.13; -0.03), -0.04 (-0.09; 0.01), -0.08 (-0.13; -0.04), -0.17 (-0.21; -0.12)], respectively. No associations were found between NO2 and EC and corneal nerve measures.ConclusionsOur population-based study demonstrated that exposure to higher levels of PM2.5 and PM10 are associated with higher levels of corneal neurodegeneration, estimated from lower corneal nerve measures. Our results suggest that air pollution may be a determinant for neurodegeneration assessed in the cornea and may impact the ocular surface health as well.

Traumatic peripheral nerve injuries in young Korean soldiers: a recent 10-year retrospective study.

Traumatic peripheral nerve injury (PNI), which occurs in up to 3% of trauma patients, is a devastating condition that often leads to permanent disability. However, knowledge of traumatic PNI is limited. We describe epidemiology and clinical characteristics of traumatic PNI in Korea and identify the predictors of traumatic complete PNI. A list of enlisted soldier patients who were discharged from military service due to PNI over a 10-year period (2012-2021) was obtained, and their medical records were reviewed. Patients were classified according to the causative events (traumatic vs. nontraumatic) and injury severity (complete vs. incomplete). Of traumatic PNIs, we compared the clinical variables between the incomplete and complete PNI groups and identified predictors of complete PNI. Of the 119 young male patients who were discharged from military service due to PNI, 85 (71.4%) were injured by a traumatic event; among them, 22 (25.9%) were assessed as having a complete injury. The most common PNI mechanism (n=49, 57.6%), was adjacent fractures or dislocations. Several injury-related characteristics were significantly associated with complete PNI: laceration or gunshot wound, PNI involving the median nerve, PNI involving multiple individual nerves (multiple PNI), and concomitant muscular or vascular injuries. After adjusting for other possible predictors, multiple PNI was identified as a significant predictor of a complete PNI (odds ratio, 3.583; P=0.017). In this study, we analyzed the characteristics of enlisted Korean soldiers discharged due to traumatic PNI and found that the most common injury mechanism was adjacent fracture or dislocation (57.6%). Patients with multiple PNI had a significantly increased risk of complete injury. The results of this study contribute to a better understanding of traumatic PNI, which directly leads to a decline in functioning in patients with trauma.

Analgesic Effect of Caudal and Abdominal Nerve Blocks among Children Undergoing Inguinal Surgeries: An Original Research.

Pediatric inguinal surgeries sometimes cause considerable post-operative pain that requires effective analgesics. Caudal and abdominal nerve blocks may help this population with pain. It is uncertain how successful they are compared. A randomized controlled trial included 70 pediatric inguinal surgery patients. An abdominal (ANB) or caudal nerve block (CNB) was randomly assigned to participants in addition to usual analgesic treatment. Post-operative pain was measured at various times using a standardized scale. The initial rescue analgesia time and dose were recorded. Statistics were used to compare CNB and ANB results. The CNB and ANB groups were demographically similar. At every time point, the two groups' analgesic usage and post-operative pain were similar. No serious adverse events occurred in either group. CNB and ANB provide equivalent analgesia for pediatric inguinal surgeries. Both approaches alleviate pain well and have similar post-operative effects. Individual nerve block approaches must be chosen based on patient features and clinical considerations. More research is needed to determine each procedure's long-term safety and results.

Nerve cross-sectional area from childhood to old age: A high-resolution nerve ultrasound study.

Nerve cross-sectional area (CSA) is not constant over the human lifespan. The relationship between an increasing CSA and age has been described as a linear positive correlation, but few studies have found a linear decrease in nerve size with older age. The aim of the present study was to analyze the development of nerve CSA in a healthy population from early childhood to old age using high-resolution ultrasound. The median, ulnar, radial and sural nerves were examined bilaterally at 18 nerve sites in 110 healthy children, adolescents and adults aged between 2 and 98 years. The CSA of every nerve site was evaluated separately and in different age groups. The correlation of CSA with age, height and weight was analyzed in a linear, logarithmic and quadratic model and correlation coefficients were compared in a goodness-of-fit analysis. Models were then adjusted for weight and height. Linear CSA-age correlations showed the lowest correlation coefficients for all nerve sites. An inverted parabolic curve suggesting a quadratic correlation of CSA and age was the best-fitting model. Weight and height had a higher predictive value than age in adjusted models. There is an increase in nerve size during childhood and adolescence and a trend towards a decrease in old age, suggesting an inverted parabolic curve partly explained by age-related changes in weight and height. Enlarged nerves in elderly individuals should not be attributed to age alone.

Localization of the greater occipital nerve through palpation of bony landmarks: A cadaveric study

Objectiveto provide anatomic confirmation that standard methods which practitioners skilled in palpation use, can reliably identify the most likely site of emergence of the greater occipital nerve in most patients. The location and frequency of subcutaneous emergence of the greater occipital nerve and occipital artery with respect to the external occipital protuberance-mastoid line are reported. MethodsThe external occipital protuberance and the mastoid processes were identified by palpation bilaterally on 57 body donors and the medial trisection point of a line connecting these bony landmarks was identified. A 4 cm circular dissection guide divided into 4 quadrants was centered on the trisection point and used to guide the removal of a circle of skin. The in-situ location of the nerve and artery were exposed by deep dissection within the circle. The frequency of the emergence and occurrence of the nerve and artery by quadrant were analyzed. ResultsIn 114 total dissections the greater occipital nerve was found to emerge within the circle 96 times (84%) and the occipital artery 100 times (88%). The nerve (90%) and artery (81%) emerged from the two inferior quadrants most of the time with no difference noted between male and female donors. The greater occipital nerve and occipital artery were found to emerge together most commonly in inferior lateral quadrant. Branches of the nerve and artery traveled together most frequently through the two lateral quadrants. ConclusionThis study confirmed that the medial trisection point of the external occipital protuberance-mastoid line can be located via palpation and reliably used to pinpoint the subcutaneous emergence of the greater occipital nerve and occipital artery in most individuals. When relying on palpation alone to identify the trisection point in the clinic, infusion of nerve block inferior and lateral to this point is most likely to bathe the greater occipital nerve in anesthetic.

Reference values for nerve conduction studies of the peroneal, tibial, and sural nerve derived from a large population-based cohort: Associations with demographic and anthropometric characteristics-The Maastricht study.

Nerve conduction studies (NCSs) are widely used to support the clinical diagnosis of neuromuscular disorders. The aims of this study were to obtain reference values for peroneal, tibial, and sural NCSs and to examine the associations with demographic and anthropometric factors. In 5099 participants (aged 40-79 years) without type 2 diabetes of The Maastricht Study, NCSs of peroneal, tibial, and sural nerves were performed. Values for compound muscle action potential (CMAP) and sensory nerve action potential amplitude, nerve conduction velocity (NCV), and distal latency were acquired. The association of age, sex, body mass index (BMI), and height with NCS values was determined using uni- and multivariate linear regression analyses. Detailed reference values are reported per decade for men and women. Significantly lower NCVs and longer distal latencies were observed in all nerves in older and taller individuals as well as in men. In these groups, amplitudes of the tibial and sural nerves were significantly lower, whereas a lower peroneal nerve CMAP was only significantly associated with age. BMI showed a multidirectional association. After correction for anthropometric factors in the multivariate analysis, the association between sex and NCS values was less straightforward. These values from a population-based dataset could be used as a reference for generating normative values. Our findings show the association of NCS values with anthropometric factors. In clinical practice, these factors can be considered when interpreting NCS values.

Evaluation of the Anatomical and Radiological Morphometry of Optic Nerve and Cranium in Healthy Individuals.

This paper determined the morphometric measurements' reference values and relationship of the optic nerve and cranium in Turkish healthy individuals according to age and sex. Five hundred fifty-nine (280 females and 279 males) patients aged from 2 to 90 years were included in this study. The measurements were taken from patients having brain magnetic resonance images in sagittal, axial, and coronal sections in the radiology department. Eyeball transverse diameter, optic nerve sheath thickness (ONST), optic chiasm length, optic chiasm width, and cranium morphometric measurements of all individuals who participated in the study were taken. Except for the width of the optic chiasm, all measurements showed significant differences between the sexes (P < 0.05). In contrast, all measurement values were higher in males than females, except for the clival angle. According to the result of Pearson correlation analysis, in which the existence of a relationship between ONST and craniometric measurements was evaluated, a low but significant correlation was found between ONST and craniometric measurements (r < 0.4; P < 0.05). In the post hoc test performed to compare the decades, it was seen that the most significant changes in our measurements were in the 2 to 10 age range and the measurement values decreased in old age. We think that revealing the age and sex-related changes in the optic nerve and cranium morphometry of our population anatomically and radiologically will be an important source in terms of creating reference values for our population.

Mapping of individual sensory nerve axons from digits to spinal cord with the transparent embedding solvent system.

Achieving uniform optical resolution for a large tissue sample is a major challenge for deep imaging. For conventional tissueclearing methods, loss of resolution and quality in deep regions is inevitable due to limited transparency. Here we describe the Transparent Embedding Solvent System (TESOS) method, which combines tissue clearing, transparent embedding, sectioning and block-face imaging. We used TESOS to acquire volumetric images of uniform resolution for an adult mouse whole-body sample. The TESOS method is highly versatile and can be combined with different microscopy systems to achieve uniformly high resolution. With a light sheet microscope, we imaged the whole body of an adult mouse, including skin, at a uniform 0.8 × 0.8 × 3.5 μm3 voxel resolution within 120 h. With a confocal microscope and a 40×/1.3 numerical aperture objective, we achieved a uniform sub-micron resolution in the whole sample to reveal a complete projection of individual nerve axons within the central or peripheral nervous system. Furthermore, TESOS allowed the first mesoscale connectome mapping of individual sensory neuron axons spanning 5 cm from adult mouse digits to the spinal cord at a uniform sub-micron resolution.

Reference Values of Shear Wave Elastography of Median and Tibial Nerve in Healthy Population: A Cross-sectional Study

Introduction: Peripheral nerves are rarely assessed using high- resolution Ultrasonography (USG). Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) scans can be costly and occasionally inaccessible. In contrast, USG provides a dynamic, portable and cost-effective method for evaluating peripheral nerves. Shear Wave Elastography (SWE) is a relatively recent ultrasound-based technique that quantitatively measures tissue stiffness. Aim: To determine the reference values for SWE measurements of the median and tibial nerves in healthy individuals and to explore potential associations with age, gender, height, weight and Body Mass Index (BMI) of the subjects. Materials and Methods: The present cross-sectional study was conducted in the Radiodiagnosis and Imaging Unit, Sri Guru Ram Das Institute of Medical Sciences and Research, Sri Amritsar, Punjab, India, from October 2022 to April 2024, involved 100 subjects (45 males and 55 females). Subjects were deemed eligible for the study following evaluation by a general physician. The study was conducted over a period of one year. High-resolution real-time USG was utilised to assess the median and tibial nerves in both arms and legs bilaterally. SWE was conducted on the tibial and median nerves, and the velocities generated were subsequently evaluated to establish baseline levels for the peripheral nerves. Collected data were transformed, coded and entered into Microsoft Excel, then analysed using Statistical Package for Social Sciences (SPSS) software version 25.0 (SPSS-PC-25). Parametric data were expressed as mean±Standard Deviation (SD) or median and compared using the Mann-Whitney U test. Results: The mean age of healthy subjects was 41.18±12.34 years, while the weight and height were 72.59±7.44 kg and 172.74±6.75 cm, respectively. The average velocities generated in healthy subjects (45 males and 55 females) using SWE were found to be 3.606±0.133 m/s and 3.632±0.173 m/s for the left and right median nerves (p-value &gt;0.05), and 3.626±0.140 m/s and 3.623±0.138 m/s for the left and right tibial nerves (p-value&gt;0.05), respectively. The SWE measurements obtained from the bilateral median and tibial nerves showed no significant differences in their values, indicating no significant association (p-value&gt;0.05). No significant correlation was found between the SWE measurements and age, sex, height, weight, or BMI of the subjects (p-value&gt;0.05). Conclusion: The present study serves as an initial step in gathering tibial nerve stiffness values from healthy participants using SWE and exploring the factors affecting nerve stiffness.

Intradural Extramedullary Spinal Tumors: A Clinical Study and Management without the Aid of Nerve Monitoring

Abstract Background: The incidence of primary spinal cord tumors is less and the true incidence is still not known and various studies are still being done. These tumors are benign and slow growing, and they generally present with pain – either radiculopathy or axial back pain or focal neurological deficits due to the loss of roots, myelopathy from spinal cord compression, or cauda equina symptoms due to chronic compression. Early diagnosis and operation are gratifying as the lesions are mostly benign and can be completely resected as well as preservation of functionality if operated as early as possible. Although rare, an inadvertent neurological injury during surgery is a concerning complication that can potentially be prevented with the assistance of intraoperative nerve monitoring (IONM). This technology enables real-time assessment of spinal cord function by providing feedback from sensory tracts, motor tracts, and individual nerve roots. However, the definitive requirement for IONM in the treatment of a highly curable condition is still under consideration. Objective: our study aims at studying the clinical features of intradural extramedullary tumors and their operative management without nerve monitoring. Material and Methods: Patients with intradural extramedullary (IDEM) spinal cord tumors who fit the inclusion criteria and who were willing to investigations, surgical procedures, and follow up were enrolled in the study, and consent was obtained. Patient assessment was done clinically by McCormick’s Scale and radiologically by magnetic resonance imaging. Patients who underwent operation were followed up. The data was collected and analysed using SPSS software. Results: Nineteen patients were enrolled in the study. The age group ranged from 6 years to 79 years. There were 13 females and 6 males in the study group. The common presenting complaints were backache and upper and lower limb pain. Nine out of the 19 patients underwent operative procedures after thorough radiological and clinical evaluation. Histopathology showed five cases of schwannoma and four cases of meningioma. The mean McCormick’s Scale preoperatively was 4.11, whereas postoperatively, it was 3.10. The operative procedures were performed without the aid of IONM, yet there were no inadvertent intraoperative injuries and postoperative outcomes were good. Our study data were comparable with other studies. Conclusion: IDEM tumors, though technically challenging to operate, have excellent results in terms of outcomes due to their benign characteristics as well as complete resectability. Therefore, it is essential to conduct a comprehensive examination and imaging for patients experiencing backaches and weakness. Following a careful evaluation, early surgical intervention should be considered, as the timeliness of the surgery contributes to enhanced outcomes. The unavailability of nerve monitoring did not portend any added risk of surgery if done meticulously though its aid would make the operative procedure safer and gross resection better.

Selective dorsal rhizotomy using a 3D high definition exoscope.

Selective dorsal rhizotomy (SDR) is an established neurosurgical technique for children with spastic diplegia secondary to cerebral palsy. Meticulous intraoperative testing of individual nerve roots with electromyography in tandem with the on-site neurorehabilitation team is recommended for good clinical outcomes. The standard approach requires the neurosurgeons to spend extended time under the traditional operating microscope. In this video, the authors describe the use of a 3D exoscope system for SDR. Overall, the 3D exoscope improves ergonomics and reduces musculoskeletal fatigue for the operating neurosurgeons. Furthermore, it provides excellent visualization of important structures, allowing safe and efficient completion of the procedure. The video can be found here: https://stream.cadmore.media/r10.3171/2023.10.FOCVID23105.

Research on the Pathogenesis of Hemifacial Spasm through Electrophysiological Studies

The cause of hemifacial spasm (HFS) is commonly linked to vascular compression of the facial nerve at the root exit zone. Microvascular decompression has become the most effective treatment for HFS. However, despite numerous electrophysiological studies investigating factors such as ephaptic transmission, ectopic excitation between individual nerve fibers, and hyperexcitability of the facial motor nucleus, there is still debate about the exact pathogenesis of HFS. For over 40 years, researchers have been conducting electrophysiological studies in clinical settings to better understand the pathogenesis of HFS. These studies have employed techniques including the lateral spread response, blink reflex test, facial F-waves, and transcranial electrical stimulation. Although a peripheral nerve mechanism was historically considered most likely to be responsible for this condition, recent studies are increasingly pointing to a central mechanism as the primary culprit behind HFS. This article seeks to shed light on the pathogenesis of HFS by reviewing the key findings from electrophysiological studies carried out over the years.

Independent association of the Meckel’s cave with trigeminal neuralgia and development of a screening tool

PurposeTo 1) investigate the association of the properties of the Meckel’s cave (MC) with TN occurrence (i.e., affected vs. unaffected nerves) and whether such association was independent of neurovascular contact (NVC); and 2) develop an objective screening tool for TN. Materials and methodsTwo hundred and nineteen trigeminal nerves were included. (The severity of) NVC was identified for individual nerve, and a set of 107 radiomic features were extracted to characterize various properties of each MC. Both procedures were primarily based on magnetic resonance imaging sequences. A radiomic score (Rad-score) was constructed for each MC to integrate the features associated with TN occurrence. Independent t-test and logistic regression were conducted to assess the association and develop the screening tool mentioned above. ResultsTwelve features were selected to build the Rad-score, with the Inverse Difference Moment Normalized (IDMN) having the greatest weight. The Rad-score was significantly (p ≤ 0.05) higher in the affected compared to the unaffected nerves, irrespective of NVC. The Rad-score and NVC were incorporated in the regression model/screening tool, which demonstrated an acceptable discriminating ability (C-statistic = 0.84). ConclusionThis study has identified a potential association of the properties/features of the MC with TN occurrence, probably involving the demyelination and axonal injury of the trigeminal ganglion within the MC as suggested by the IDMN. Such association may be independent of NVC. This finding may provide new insight into the etiology and/or pathophysiology of TN. The screening tool, which demonstrated an acceptable discriminating ability, may contribute to an improvement in its diagnosis.