Asymptomatic Nerve Research Articles

A combined radiomics and anatomical features model enhances MRI-based recognition of symptomatic nerves in primary trigeminal neuralgia.

The diagnosis of primary trigeminal neuralgia (PTN) in radiology lacks the gold standard and largely depends on the identification of neurovascular compression (NVC) using magnetic resonance imaging (MRI) water imaging sequences. However, relying on this imaging sign alone often fails to accurately distinguish the symptomatic side of the nerve from asymptomatic nerves, and may even lead to incorrect diagnoses. Therefore, it is essential to develop a more effective diagnostic tool to aid radiologists in the diagnosis of TN. This study aims to establish a radiomics-based machine learning model integrating multi-region of interest (multiple-ROI) MRI and anatomical data, to improve the accuracy in differentiating symptomatic from asymptomatic nerves in PTN. A retrospective analysis of MRI data and clinical anatomical data was conducted on 140 patients with clinically confirmed PTN. Symptomatic nerves of TN patients were defined as the positive group, while asymptomatic nerves served as the negative group. The ipsilateral Meckel's cavity (MC) was included in both groups. Through dimensionality reduction analysis, four radiomics features were selected from the MC and 24 radiomics features were selected from the trigeminal cisternal segment. Thirteen anatomical features relevant to TN were identified from the literature, and analyzed using univariate logistic regression and multivariate logistic regression. Four features were confirmed as independent risk factors for TN. Logistic regression (LR) models were constructed for radiomics model and clinical anatomy, and a combined model was developed by integrating the radiomics score (Rad-Score) with the clinical anatomy model. The models' performance was evaluated using receiver operating characteristic curve (ROC) curves, calibration curves, and decision curve analysis (DCA). The four independent clinical anatomical factors identified were: degree of neurovascular compression, site of neurovascular compression site, thickness of the trigeminal nerve root, and trigeminal pons angle (TPA). The final combined model, incorporating radiomics and clinical anatomy, achieved an area under the curve (AUC) of 0.91/0.90 (95% CI: 0.87-0.95/0.81-0.96) and an accuracy of approximately 82% in recognizing symptomatic and normal nerves. The combined radiomics and anatomical model provides superior recognition efficiency for the symptomatic nerves in PTN, offering valuable support for radiologists in diagnosing TN.

Consistency of the results of neurophysiological examinations with clinical diagnosis formed by the referring physician in ambulatory medical care.

Access to electroneurographic/electromyographic (ENG/EMG) examinations and the number of patients referred for electrodiagnostic (EDX) examination are increasing. We aimed to determine the accuracy of the initial clinical diagnosis made by outpatient medical care physicians who referred patients to the EMG laboratory. We analyzed referrals and EDX results of all patients who visited EMG laboratory of the Department of Clinical Neurophysiology, Institute of Psychiatry and Neurology in Warsaw in 2021. Examinations were performed in accordance with the standards and norms adopted in our laboratory by EMG-certified neurologists, regarding the initial diagnosis stated by referring physicians. A total of 454 EDX results from 412 patients were analyzed. Most of patients (54.6%) were referred with diagnosis of carpal tunnel syndrome (CTS), followed by single nerves damage (18.7%), polyneuropathy (18.1%), tetany (7.0%), myasthenia gravis (1.3%) or myopathy (0.2%). The result of the ENG/EMG examination was: diagnosis confirmation (61.9%), a new clinically significant diagnosis or additional asymptomatic nerve damage (32.4%), and normal examination result (25.1%) of patients. Electrophysiological examination most often confirmed the referral diagnosis in patients with suspected CTS (75.4%), followed by single nerves damage (51.8%), polyneuropathy (48.8%), tetany (31.3%) and the least for myasthenia gravis and myopathy (0%). Our study showed frequent inconsistency of the EDX results with the clinical diagnosis formed by the referring physician. A high percentage of normal test results was noted. Initial diagnosis and the scope of EDX examination should be determined by detailed interview and physical examination.

Sagittal Angle of the Trigeminal Nerve at the Porus Trigeminus: A Novel Measurement to Distinguish Different Causes of Classic Trigeminal Neuralgia.

Classic trigeminal neuralgia is a clinical syndrome of facial pain, most often attributable to vascular compression of the proximal cisternal segment of the trigeminal nerve and treatable with microvascular decompression of the nerve. Some patients, however, meet all clinical criteria for classic trigeminal neuralgia yet do not respond to microvascular decompression. Because the reasons for surgical failure are not well understood, the aim of this study was to determine if a subset of patients with classic trigeminal neuralgia could be distinguished by measuring the angle of the trigeminal nerve in the sagittal plane as the nerve traverses the porus trigeminus. We retrospectively identified patients with either classic trigeminal neuralgia (n = 300) or hemifacial spasm (n = 300) who had undergone MR imaging, including 3-plane steady-state free precession imaging. Patients with hemifacial spasm served as controls. On sagittal steady-state free precession images, we measured the angle of each trigeminal nerve as it crosses through the porus trigeminus into the Meckel cave (SATNaPT). In patients with classic trigeminal neuralgia, we separated the nerves into symptomatic and asymptomatic sides. We compared these 3 groups using the Student t test. Control patients had a mean SATNaPT of 170° (SD, 11°) with a normal distribution. The contralateral asymptomatic nerve in patients with classic trigeminal neuralgia had the same distribution of angles. The symptomatic nerves in patients with classic trigeminal neuralgia had a bimodal distribution; 83% of patients fell into the same distribution as the asymptomatic nerves, but the other 15% had an average angle of 143° (SD, 7°). This difference was statistically significant (P < .0001). Patients with the clinical syndrome of classic trigeminal neuralgia fell into 2 categories based on the radiologic measurement of the SATNaPT. Most patients had an anatomically normal nerve that was affected by vascular compression, but 17% of these patients had aberrant anatomy that may cause or contribute to their clinical presentation. Further study is needed to determine whether this subset of patients should receive a different surgery to better address their underlying anatomic abnormality. The SATNaPT measurement should be included in every MR imaging interpretation performed on patients with classic trigeminal neuralgia.

Clinicoradiological Evaluation of Trigeminal Neurovascular Loops: A Retrospective Cohort Study from Eastern India

Introduction: Several lesions may affect trigeminal nerve from the nucleus to peripheral branches causing facial pain, called trigeminal Neuralgia (TN). Neurovascular compression (NVC) of the trigeminal nerve is the primary cause of TN, usually occurring at the root entry zone but is known to occur in both symptomatic and asymptomatic nerves. Aim: To evaluate trigeminal neurovascular loops (NVLs) clinico- radiologically and to know the association between the shortest distance of loop as well as the severity of compression with clinical symptoms. Materials and Methods: This is a Retrospective cohort study conducted in March 2020 after collecting data from January 2017 to January 2020 in a tertiary care center of Eastern India. All the patients, detected with trigeminal NVLs by Magnetic Resonance (MR) imaging were evaluated clinically (from records) &amp; radiologically and an association is drawn between the distance of the loop, the severity of compression with symptoms. Data were analyzed using Statistical Package for Social Sciences (SPSS) statistical software version 24.0. Result: Among 103 cases studied, the symptomatic and asymptomatic loops were 76 &amp; 27. In symptomatic group, males and females were 48 (63%) and 28 (36.8%) respectively with mean age of 56 years with male:female ratio in symptomatic group of 76 cases was 1.7:1. Left-sided presentation and pain in the maxillary area were found in 39 (51.3%) and 33 (43.4%) cases. Sharp/electric current like/ lancinating pain was present in 72 (94.7%) case. Triggering factors and spontaneous onset pain were presentations in 70 (92%) and 76 (100%) cases. Magnetic Resonance Imaging (MRI) showed NVLs with a just contact to the nerve in all asymptomatic (27/27,100%) and most symptomatic cases (57/76, 75%). The superior cerebellar artery was found to be the most common vessel involved (59/76, 77.6%). Proximal and bilateral NVLs were found in 62 (82.89%) and 27 (35.9%) cases of symptomatic nerves. Severe NVC was only present in symptomatic nerves in 19 (25%) cases. Conclusion: Typical clinical features of trigeminal neuralgia include male preponderance, lancinating pain on maxillary area of left face. Compression by NVLs are most common cause of TN, among which Superior cerebellar artery is most common culprit vessel. Severe neurovascular compressions are more symptomatic. All neurovascular compressions are not always symptomatic.

Dynamic Somatosensory Evoked Potential and Magnetic Resonance Imaging in Pudendal Neuropathy

Aim: Pudendal neuropathy (PN) is a common cause of chronic perineal pain and usually diagnosed long after the onset of symptoms. Diagnostic work-up of PN mainly includes radiologic and neurophysiological studies. However, there is no established diagnostic test to confirm the clinical diagnosis. This study aims to evaluate the correlation between the dynamic pudendal somatosensory evoked potential (SEP) and pudendal magnetic resonance imaging (MRI) in patients with PN diagnosed clinically based on Nantes criteria as the gold standard for comparison. Methods: Forty-three patients (25 females, 18 males) were included in the study. Dynamic pudendal SEP as a novel method, which includes both provocative positioning and stimulation of each side separately, and pudendal MRI were performed in each patient. Results: Dynamic pudendal SEPs were found to be abnormal in 42, normal in 12 of the 54 clinically symptomatic nerves and abnormal in 2, normal in 30 of the 32 clinically asymptomatic nerves. Pudendal MRI was abnormal in 19, normal in 35 of the 54 clinically symptomatic nerves and abnormal in 8 and normal in 24 of the 32 clinically asymptomatic nerves. There was 84% agreement between clinical diagnosis and dynamic pudendal SEP (high sensitivity and specificity), 49% agreement between clinical diagnosis and pudendal MRI (low sensitivity and acceptable specificity), 53% agreement between dynamic pudendal SEP and pudendal MRI. Conclusions: The novel dynamic pudendal SEP method seems to be useful in supporting the clinical diagnosis of PN, while pudendal MRI lacks sufficient sensitivity to be used alone in diagnosis of PN.

ASYMPTOMATIC RETINAL NERVE FIBER LAYER THICKENING IN A PATIENT WITH ATAXIA.

In Brief This is a unique case of autosomal recessive spastic ataxia of Charlevoix–Saguenay that reports the wide spectrum of retinal findings using optical coherence tomography.

Trigeminal neurovascular contact in SUNCT and SUNA: a cross-sectional magnetic resonance study.

Emerging data-points towards a possible aetiological and therapeutic relevance of trigeminal neurovascular contact in short lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and perhaps in short lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA). We aimed to assess the prevalence and significance of trigeminal neurovascular contact in a large cohort of consecutive SUNCT and SUNA patients and evaluate the radiological differences between them. The standard imaging protocol included high spatial and nerve-cistern contrast resolution imaging acquisitions of the cisternal segments of the trigeminal nerves and vessels. MRI studies were evaluated blindly by two expert evaluators and graded according to the presence, location and degree of neurovascular contact. The degree of contact was graded as with or without morphological changes. Neurovascular contact with morphological changes was defined as contact with distortion and/or atrophy. A total of 159 patients (SUNCT = 80; SUNA = 79) were included. A total of 165 symptomatic and 153 asymptomatic trigeminal nerves were analysed. The proportion of neurovascular contact on the symptomatic trigeminal nerves was higher (80.0%) compared to the asymptomatic trigeminal nerves (56.9%). The odds on having neurovascular contact over the symptomatic nerves was significantly higher than on the asymptomatic nerves [odds ratio (OR): 3.03, 95% confidence interval (CI) 1.84-4.99; P < 0.0001]. Neurovascular contact with morphological changes were considerably more prevalent on the symptomatic side (61.4%), compared to the asymptomatic side (31.0%) (OR 4.16, 95% CI 2.46-7.05; P < 0.0001). On symptomatic nerves, neurovascular contact with morphological changes was caused by an artery in 95.0% (n = 77/81). Moreover, the site of contact and the point of contact around the trigeminal root were respectively proximal in 82.7% (67/81) and superior in 59.3% (48/81). No significant radiological differences emerged between SUNCT and SUNA. The multivariate analysis of radiological predictors associated with the symptomatic side, indicated that the presence of neurovascular contact with morphological changes was strongly associated with the side of the pain (OR: 2.80, 95% CI 1.44-5.44; P = 0.002) even when adjusted for diagnoses. Our findings suggest that neurovascular contact with morphological changes is involved in the aetiology of SUNCT and SUNA. Along with a similar clinical phenotype, SUNCT and SUNA also display a similar structural neuroimaging profile, providing further support for the concept that the separation between them should be abandoned. Furthermore, these findings suggest that vascular compression of the trigeminal sensory root, may be a common aetiological factor between SUNCT, SUNA and trigeminal neuralgia thereby further expanding the overlap between these disorders.

Degenerative lumbar scoliosis: added value of coronal images to routine lumbar MRI for nerve root compromise.

Radiating pain in degenerative scoliosis is primary indication for surgery. However, axial and sagittal MR images are limited for identifying nerve root compromise. Therefore, we aimed to assess the value of coronal images for evaluating nerve root compromise in degenerative scoliosis. Forty-six patients (mean 70 years; range 41-91 years; 8 men) with degenerative scoliosis were enrolled. Coronal images were added to routine MRI. Two radiologists independently reviewed 350 nerve roots in two MRI sets: sagittal images alone (set 1) and coronal and sagittal images combined (set 2). The following features were evaluated: interpedicular height, lateral osteophyte, asymmetric bulging disc, lateral listhesis, anterolisthesis, axial rotation angle, facet arthrosis, ligamentum flavum thickening, and pseudoarticulation. Symptomatic levels were determined by transforaminal selective nerve root block. There were 80 symptomatic and 270 asymptomatic nerve roots. The sensitivity (86%) and accuracy (93%) of set 2 were significantly higher than set 1 (53% and 87%) for radiculopathy, while specificity was similar between two sets (set 1, 97%; set 2, 95%). The AUC was significantly different between two sets (set 1, 0.853; set 2, 0.942). The negative interpedicular height difference, longer lateral osteophyte, asymmetric bulging disc, lateral listhesis, negative axial rotation angle difference, and pseudoarticulation were associated with change of grades between set 1 and set 2. Coronal images are helpful for diagnosing nerve root compromise in patients with degenerative scoliosis. • Sagittal and axial images have low sensitivity for detection of extraforaminal nerve root compromise in degenerative scoliosis. • Addition of coronal images may improve the sensitivity in nerve root compromise. • The structural changes that may contribute to nerve root compromise can also be easily assessed with coronal images.

Significance of degree of neurovascular compression in surgery for trigeminal neuralgia.

The aim of this study was to identify preoperative imaging predictors of surgical success in patients with classic trigeminal neuralgia (cTN) undergoing microvascular decompression (MVD) via retrospective multivariate regression analysis. All included patients met criteria for cTN and underwent preoperative MRI prior to MVD. MR images were blindly graded regarding the presence and severity (i.e., mild or severe) of neurovascular compression (NVC). All patients were contacted by telephone to determine their postoperative pain status. A total of 79 patients were included in this study. Sixty-two patients (78.5%) were pain-free without medication following MVD. The following findings were more commonly observed with the symptomatic nerve when compared to the contralateral asymptomatic nerve: NVC (any form), arterial compression alone, NVC along the proximal trigeminal nerve, and severe NVC (p values < 0.0001). The only imaging variable that was a statistically significant predictor of being pain-free without medication following MVD was severe NVC. Patients with severe NVC were 6.36 times more likely to be pain-free following MVD compared to those without severe NVC (p = 0.007). In patients with cTN undergoing MVD, severe NVC on preoperative MRI is a strong predictor of an excellent surgical outcome.

Trigeminal Nerve Atrophy Predicts Pain Recurrence After Gamma Knife Stereotactic Radiosurgery for Classical Trigeminal Neuralgia.

Trigeminal nerve atrophy and neurovascular compression (NVC) are frequently observed in classical trigeminal neuralgia (CTN). To determine whether nerve characteristics contribute to Gamma Knife (Elekta AB, Stockholm, Sweden) surgery (GKS) outcomes in unilateral CTN without previous surgery. From 2006 to 2012, 67 patients with unilateral CTN without previous surgery received GKS with a maximal dose of 90 Gy delivered to the trigeminal nerve juxta brainstem. Two evaluators, blinded to the side of pain, analyzed the magnetic resonance images before GKS to obtain the parameters, including nerve cross-sectional area (CSA), vessel type of NVC, and site of NVC along the nerve. Correlations of the parameters with pain relief (Barrow Neurological Institute [BNI] grades I-IIIb) and recurrence (BNI grades VI-V) were made by using Cox regression and Kaplan-Meier analyses. The median CSA of the symptomatic nerves was significantly smaller than that of the asymptomatic nerves (4.95 vs 5.9 mm2, P<.001). After adjustment for age and sex, larger nerve CSA was associated with lower initial pain relief (hazard ratio 0.81, P=.03) and lower pain recurrence after initial response (hazard ratio 0.58, P=.02). Patients with nerve atrophy (CSA of≤4.4 mm2 after receiver operating characteristic curve analysis) had a lower 5-yr probability of maintaining pain relief after initial response than those without nerve atrophy (65% vs 86%, P=.04). Trigeminal nerve atrophy may predict pain recurrence in patients with initial post-GKS relief of CTN. Arterial and proximal NVC are not predictive of GKS outcomes. Future studies are required to determine optimal treatments for long-term pain relief in patients with CTN and trigeminal nerve atrophy.

OBLIGATORY ALTERATIONS IN THE MORPHOLOGY OF MEDIAN NERVE: A SONOGRAPHIC STUDY IN ASYMPTOMATIC INDIVIDUALS

Introduction: Median nerve is formed in axilla by contributions from medial and lateral cords of brachial plexus. It descends in the arm, forearm and then through carpal tunnel in close conjunction with flexor tendons of forearm. Carpal tunnel syndrome (CTS) is a common entrapment neuropathy. Median nerve cross sectional area (CSA) and ratio of nerve major axis to minor axis (flattening ratio) serve as potential diagnostic criteria for carpal tunnel syndrome. Median nerve cross sectional area and flattening ratio (FR) can be assessed by ultrasonography (US). Aim of the study was to assess median nerve by US and tabulate mean values for CSA and FR in asymptomatic population. This would serve to limit the cut-off values that differentiate asymptomatic nerves from neuropathic nerves. Material &amp; Methods: Study was conducted in the Department of Anatomy, KGMU, Lucknow. Fifty randomly selected asymptomatic volunteers (undergraduate students: 30 males, 20 females) participated in the study. Sonography was performed to evaluate certain morphological dimensions of median nerve. Height, weight and wrist circumference of participants were also noted. Ultrasonography was performed using high frequency linear probe and observations were made at two pre-determined sites. Observations were recorded, tabulated and analyzed. Results: Median nerve was easily observable at both sites. It was round in shape in forearm (Fo), and flattened as it reached the carpal tunnel (Ct). Among all 50 study subjects, at both sites, flattening was more on right side (FRFoRt-1.71; FRCtRt-3.08) than on left side (FRFoLt-1.66; FRCtLt-2.78). In right forearm, nerve was flatter in females (FRFoRt-1.77) as compared to males (FRFoRt-1.68). In left forearm, median nerve was slightly rounder in females (FRFoLt-1.65) as compared to males (FRFoLt-1.67). At the distal wrist crease on right side, increased flattening was observed in females (FRCtRt-3.30) as compared to males (FRCtRt-2.94), whereas on left side, at same site flattening was more in females (males FRCtLt-2.74; females FRCtLt-2.83). Conclusion: Altered FR has both diagnostic as well as prognostic values in carpal tunnel syndrome. The database generated from the study will help in facilitating comparisons between normal, asymptomatic and pathological, asymptomatic individuals.

Poisoning with Soman, an Organophosphorus Nerve Agent, Alters Fecal Bacterial Biota and Urine Metabolites: a Case for Novel Signatures for Asymptomatic Nerve Agent Exposure.

The experimental pathophysiology of organophosphorus (OP) chemical exposure has been extensively reported. Here, we describe an altered fecal bacterial biota and urine metabolome following intoxication with soman, a lipophilic G class chemical warfare nerve agent. Nonanesthetized Sprague-Dawley male rats were subcutaneously administered soman at 0.8 (subseizurogenic) or 1.0 (seizurogenic) of the 50% lethal dose (LD50) and evaluated for signs of toxicity. Animals were stratified based on seizing activity to evaluate effects of soman exposure on fecal bacterial biota and urine metabolites. Soman exposure reshaped fecal bacterial biota by altering Facklamia, Rhizobium, Bilophila, Enterobacter, and Morganella genera of the Firmicutes and Proteobacteria phyla, some of which are known to hydrolyze OP chemicals. However, analogous changes were not observed in the bacterial biota of the ileum, which remained the same irrespective of dose or seizing status of animals after soman intoxication. However, at 75 days after soman exposure, the bacterial biota stabilized and no differences were observed between groups. Interestingly, in considering just the seizing status of animals, we found that the urine metabolomes were markedly different. Leukotriene C4, kynurenic acid, 5-hydroxyindoleacetic acid, norepinephrine, and aldosterone were excreted at much higher rates at 72 h in seizing animals, consistent with early multiorgan involvement during soman poisoning. These findings demonstrate the feasibility of using the dysbiosis of fecal bacterial biota in combination with urine metabolome alterations as forensic evidence for presymptomatic OP exposure temporally to enable administration of neuroprotective therapies of the future.IMPORTANCE The paucity of assays to determine physiologically relevant OP exposure presents an opportunity to explore the use of fecal bacteria as sentinels in combination with urine to assess changes in the exposed host. Recent advances in sequencing technologies and computational approaches have enabled researchers to survey large community-level changes of gut bacterial biota and metabolomic changes in various biospecimens. Here, we profiled changes in fecal bacterial biota and urine metabolome following a chemical warfare nerve agent exposure. The significance of this work is a proof of concept that the fecal bacterial biota and urine metabolites are two separate biospecimens rich in surrogate indicators suitable for monitoring OP exposure. The larger value of such an approach is that assays developed on the basis of these observations can be deployed in any setting with moderate clinical chemistry and microbiology capability. This can enable estimation of the affected radius as well as screening, triage, or ruling out of suspected cases of exposures in mass casualty scenarios, transportation accidents involving hazardous materials, refugee movements, humanitarian missions, and training settings when coupled to an established and validated decision tree with clinical features.

Investigation of the Effect of Cervical Radiculopathy on Peripheral Nerves of the Upper Extremity With High-Resolution Ultrasonography.

Prospective, cross-sectional observational study. We aimed to investigate the effects of chronic cervical radiculopathy (CR) on the cross-sectional area (CSA) values of the cervical nerve roots (CNRs), median, ulnar, and radial nerves with high-resolution ultrasonography. Symptomatic nerve roots are wider than asymptomatic nerve roots due to the presence of edema. Peripheral nerves have also been shown to develop edema, fibrosis, and changes distal to the affected nerve as a result of mechanical compression. In addition according to "double-crush syndrome" hypothesis, the peripheral nerves are more sensitive to pressure, and a proximal nerve lesion makes the distal segment of the nerve more susceptible to anatomic deterioration by causing interruption in the axoplasmic conduction due to compression. Forty patients with chronic CR were included to the study. Both affected CNRs and the contralateral nerve roots (control group) were evaluated with high-resolution ultrasonography. Ulnar and median nerve CSA measurements were performed at four measurement points and radial nerve measurements at a single measurement point. CSA measurements were statistically significantly higher at the CNR of the affected side compared to the unaffected side. There was no statistically significant difference when affected and unaffected sides were compared in terms of measurements performed from median, ulnar, and radial nerves at all measurement points. The results of the present study indicate that the changes in the CNR caused by CR do not have any effect on the peripheral nerves. We did not find any affection in peripheral nerve CSA that might have been suggestive of double-crush syndrome in CR. 2.

MR Neurography of Greater Occipital Nerve Neuropathy: Initial Experience in Patients with Migraine.

MR imaging of peripheral nerves (MR neurography) allows improved assessment of nerve anatomy and pathology. The objective of this study was to evaluate patients with unilateral occipital neuralgia using MR neurography and to assess the differences in greater occipital nerve signal and size between the symptomatic and asymptomatic sides. In this case-control evaluation using MR neurography, bilateral greater occipital nerve caliber, signal intensity, signal-to-noise ratios, and contrast-to-noise ratios were determined by 2 observers. Among 18 subjects with unilateral occipital migraines, the average greater occipital nerve diameter for the symptomatic side was significantly greater at 1.77 ± 0.4 mm than for the asymptomatic side at 1.29 ± 0.25 mm (P = .001). The difference in nerve signal intensity between the symptomatic and asymptomatic sides was statistically significant at 269.06 ± 170.93 and 222.44 ± 170.46, respectively (P = .043). The signal-to-noise ratios on the symptomatic side were higher at 15.79 ± 4.59 compared with the asymptomatic nerve at 14.02 ± 5.23 (P = .009). Contrast-to-noise ratios were significantly higher on the symptomatic side than on the asymptomatic side at 2.57 ± 4.89 and -1.26 ± 5.02, respectively (P = .004). Intraobserver performance was good to excellent (intraclass coefficient correlation, 0.68-0.93), and interobserver performance was fair to excellent (intraclass coefficient correlation, 0.54-0.81). MR neurography can be reliably used for the diagnosis of greater occipital nerve neuropathy in patients with unilateral occipital migraines with a good correlation of imaging findings to the clinical presentation.

S63 Etiology of clinically established trigeminal neuralgia: Role of MRI

Objectives Neurovascular compression (NVC) is the commonest cause of trigeminal neuralgia (TN). The use of MRI for diagnosis and presurgical assessment is problematic, because NVC is commonly reported in asymptomatic subjects or affecting asymptomatic nerves TN patients. We reviewed the literature to evaluate the role of MRI in the diagnostics of TN. Methods Medline and Scopus were searched to identify papers on 3-D reconstruction MRI in unoperated patients with unilateral TN. Only papers with 20 patients or more with typical TN were included. Assessment had to be done by two independent radiologists blinded to the side of the pain and the clinical status of the subjects. Results 10 publications fulfilled the criteria. Neurovascular compression/contact was judged to affect 332/385 (86%) of symptomatic and 216/477 (45%) of asymptomatic nerves. Nerve atrophy was assessed in 6 studies (201 symptomatic and 275 asymptomatic nerves in total) showing consistent reduction of volume (12–24%) and cross sectional area (12–18%) in the symptomatic nerve ( p 0.01 ).Based on 7 studies, severe compression (indentation, nerve displacement) was significantly more common in symptomatic than asymptomatic nerves ( P 0.05 ). Discussion The high prevalence of ‘innocuous’ NVC of asymptomatic nerves is confirmed. NVC is more likely to be the cause of TN when nerve atrophy is present and/or the compression is severe (and is at the root entry zone). No exact cutoff values can yet be presented however. Conclusion NVC is clinically relevant for TN only if associated with evidence of anatomical changes in the symptomatic nerve. Significance The role of MRI in assessment of patient with TN clarified.

Hereditary neuropathy with liability to pressure palsy in patients under 30 years old: Neurophysiological data and proposed electrodiagnostic criteria.

In young patients with mononeuropathy who lack family history and precipitating factors, hereditary neuropathy with liability to pressure palsy (HNPP) may be a possibility. Our objective is to propose neurophysiological criteria for HNPP in patients <30 years of age. We conducted a national multicenter retrospective clinical and neurophysiological study in patients under 30 with genetically confirmed HNPP. All of the 51 patients included in the study had at least 1 demyelinating pattern in 2 asymptomatic nerves, and 3 abnormalities were found in almost 90%, including slowed motor nerve conduction velocity across the elbow in at least 1 ulnar nerve (97.5%), increased distal motor latency (DML) in at least 1 fibular nerve (95.8%), and increased DML in both median nerves (89%). Age influenced DML slightly only in the fibular nerve. Dissemination of nerve involvement in HNPP incites to perform a complete nerve conduction study. including bilateral ulnar, fibular, and median nerves. Muscle Nerve 57: 217-221, 2018.

Ultrasonographic findings of posterior interosseous nerve syndrome.

PurposeThe purpose of this study was to evaluate the ultrasonographic findings associated with posterior interosseous nerve (PIN) syndrome.MethodsApproval from the Institutional Review Board was obtained. A retrospective review of 908 patients' sonographic images of the upper extremity from January 2001 to October 2010 revealed 10 patients suspicious for a PIN abnormality (7 male and 3 female patients; mean age of 51.8±13.1 years; age range, 32 to 79 years). The ultrasonographic findings of PIN syndrome, including changes in the PIN and adjacent secondary changes, were evaluated. The anteroposterior diameter of the pathologic PIN was measured in eight patients and the anteroposterior diameter of the contralateral asymptomatic PIN was measured in six patients, all at the level immediately proximal to the proximal supinator border. The size of the pathologic nerves and contralateral asymptomatic nerves was compared using the Mann-Whitney U test.ResultsSwelling of the PIN proximal to the supinator canal by compression at the arcade of Fröhse was observed in four cases. Swelling of the PIN distal to the supinator canal was observed in one case. Loss of the perineural fat plane in the supinator canal was observed in one case. Four soft tissue masses were noted. Secondary denervation atrophy of the supinator and extensor muscles was observed in two cases. The mean anteroposterior diameter of the pathologic nerves (n=8, 1.79±0.43 mm) was significantly larger than that of the contralateral asymptomatic nerves (n=6, 1.02±0.22 mm) (P=0.003).ConclusionUltrasonography provides high-resolution images of the PIN and helps to diagnose PIN syndrome through visualization of its various causes and adjacent secondary changes.

Diffusion tensor imaging of lumbar spinal nerve in subjects with degenerative lumbar disorders

Recently several authors have reported that diffusion tensor imaging (DTI) might provide a new understanding of sciatica. The purpose of this study was to investigate the clinical feasibility of DTI for the evaluation of lumbar spinal nerve of patients with sciatica associated with lumbar degenerative disorders. Thirty-four patients (25men, mean age63. 3years) with degenerated lumbar disease, 14 patients with lumbar spinal stenosis with foraminal stenosis, 12 with lumbar spinal stenosis without foraminal stenosis, five with lumbar disc herniation, two with discogenic low back pain, and one with spondylolysis who underwent 3.0T magnetic resonance (MR) imaging and surgical treatment were included in the present study. Fractional anisotropy (FA) was calculated from an FA map, and tractography was investigated. In asymptomatic nerves, tractography showed all L3–S1 spinal nerve roots clearly. Abnormalities of tractography were classified into three types by shape; “Disrupted”, “Narrowing”, and “Tapering”. More abnormalities of tractography were found in patients with lumbar spinal stenosis, and especially in patients with foraminal stenosis. The disrupted type was the most common. The mean FA of entrapped symptomatic nerves was less than seen on the intact side. This study demonstrates that tractography shows abnormal findings for nerve roots in lumbar spinal degeneration and that FA decreases in symptomatic roots. DTI may offer not only morphological evaluation, but also quantitative evaluation. We believe that DTI can be used as a tool for the diagnosis of lumbar spinal degenerative disease.

MRI-based Volumetry in Trigeminal Neuralgia

Objective A noticeable contact between a blood vessel and the root entry zone (REZ) of the trigeminal nerve (CN V) is considered as the major cause of trigeminal neuralgia (TN) known as neurovascular compression (NVC). Earlier volumetric studies using magnetic resonance imaging (MRI) attempted to prove an atrophy of the affected trigeminal nerves in comparison to the unaffected contralateral trigeminal nerves. They described lower volumes on the affected sides in all their cases and criteria for diagnostics and surgery were concluded from these results. The goal of this study was to verify the difference in volume of the symptomatic and asymptomatic trigeminal nerves. Methods 100 patients with TN were prospectively examined using highresolution MRI and segmentation of the cisternal portion of the trigeminal nerve by defining a region of interest in the transversal sections. The resulting nerve volumes were compared by intra individual, bilateral comparison (t-test for paired samples, p < 0.05). Results 63% of the examined patients showed a lower volume of the cisternal portion of CN V on the affected sides. In 35% of the investigated individuals the volumes of the affected trigeminal nerves were larger than the nerve volumes on the unaffected sides. 2% of the examined patients showed identical volumes on either side. Conclusion In comparison to previous studies the described atrophy of CN V based on NVC could be reproduced in 63% of patients with TN and not in all patients with high-resolution MRI. Consequently the difference in nerve volume between the affected and unaffected trigeminal nerves cannot be proved for all cases of trigeminal neuralgia.

Trigeminal neuralgia: differences in magnetic resonance imaging characteristics of neurovascular compression between symptomatic and asymptomatic nerves.

Neurovascular compression (NVC) of the trigeminal nerve is the primary cause of trigeminal neuralgia (TN) but is known to occur in both symptomatic and asymptomatic nerves. The purposes of this study were to evaluate the relationship between the magnetic resonance imaging (MRI) findings regarding the site of NVC and the manifestation of TN symptoms. In 147 patients with unilateral TN, the presence or absence of NVC was evaluated on MRI in both symptomatic and asymptomatic nerves. In cases with NVC, the shortest distance from the trigeminal nerve root to the responsible vessel was measured. The mean distance from the trigeminal nerve root to the site of NVC in asymptomatic nerves (3.85 ± 2.69 mm) was significantly greater than that in symptomatic nerves (0.94 ± 1.27 mm). When the distance was 3 mm or less, the rate of the manifestation of TN symptoms was 83.1% (103/124). On the other hand, it was only 19.6% (9/46) in cases with a distance of greater than 3 mm. Whether or not NVC of the trigeminal nerve was symptomatic was closely related to the distance from the trigeminal nerve root to the responsible blood vessel.