Fascicular Lesions Research Articles

Magnetic resonance neurography in spinal cord injury: Imaging findings and clinical significance.

It is unknown whether changes to the peripheral nervous system following spinal cord injury (SCI) are relevant for functional recovery or the development of neuropathic pain below the level of injury. Magnetic resonance neurography (MRN) at 3 T allows detection and localization of structural and functional nerve damage. This study aimed to combine MRN and clinical assessments in individuals with chronic SCI and nondisabled controls. Twenty participants with chronic SCI and 20 controls matched for gender, age, and body mass index underwent MRN of the L5 dorsal root ganglia (DRG) and the sciatic nerve. DRG volume, sciatic nerve mean cross-sectional area (CSA), fascicular lesion load, and fractional anisotropy (FA), a marker for functional nerve integrity, were calculated. Results were correlated with clinical assessments and nerve conduction studies. Sciatic nerve CSA and lesion load were higher (21.29 ± 5.82 mm2 vs. 14.08 ± 4.62 mm2 , p < 0.001; and 8.70 ± 7.47% vs. 3.60 ± 2.45%, p < 0.001) in individuals with SCI compared to controls, whereas FA was lower (0.55 ± 0.11 vs. 0.63 ± 0.08, p = 0.022). DRG volumes were larger in individuals with SCI who suffered from neuropathic pain compared to those without neuropathic pain (223.7 ± 53.08 mm3 vs. 159.7 ± 55.66 mm3 , p = 0.043). Sciatic MRN parameters correlated with electrophysiological results but did not correlate with the extent of myelopathy or clinical severity of SCI. Individuals with chronic SCI are subject to a decline of structural peripheral nerve integrity that may occur independently from the clinical severity of SCI. Larger volumes of DRG in SCI with neuropathic pain support existing evidence from animal studies on SCI-related neuropathic pain.

Six-month periodic fasting does not affect somatosensory nerve function in type 2 diabetes patients.

Current strategies for preventing diabetic sensorimotor polyneuropathy (DSPN) are limited mainly to glucose control but rapid decrease of glycemia can lead to acute onset or worsening of DSPN. The aim of this study was to examine the effects of periodic fasting on somatosensory nerve function in patients with type 2 diabetes (T2D). Somatosensory nerve function was assessed in thirty-one patients with T2D (HbA1c 7.8 ± 1.3% [61.4 ± 14.3 mmol/mol]) before and after a six-month fasting-mimicking diet (FMD; n=14) or a control Mediterranean diet (M-diet; n=17). Neuropathy disability score (NDS), neuropathy symptoms score (NSS), nerve conduction velocity and quantitative sensory testing (QST) were analyzed. 6 participants of the M-Diet group and 7 of the FMD group underwent diffusion-weighted high-resolution magnetic resonance neurography (MRN) of the right leg before and after the diet intervention. Clinical neuropathy scores did not differ between study groups at baseline (64% in the M-Diet group and 47% in the FMD group had DSPN) and no change was found after intervention. The differences in sensory NCV and sensory nerve action potential (SNAP) of sural nerve were comparable between study groups. Motor NCV of tibial nerve decreased by 12% in the M-Diet group (P=0.04), but did not change in the FMD group (P=0.39). Compound motor action potential (CMAP) of tibial nerve did not change in M-Diet group (P=0.8) and increased in the FMD group by 18% (P=0.02). Motor NCV and CMAP of peroneal nerve remained unchanged in both groups. In QST M-diet-group showed a decrease by 45% in heat pain threshold (P=0.02), FMD group showed no change (P=0.50). Changes in thermal detection, mechanical detection and mechanical pain did not differ between groups. MRN analysis showed stable fascicular nerve lesions irrespective of the degree of structural pathology. Fractional anisotropy and T2-time did not change in both study groups, while a correlation with the clinical degree of DSPN could be confirmed for both. Our study shows that six-month periodic fasting was safe in preserving nerve function and had no detrimental effects on somatosensory nerve function in T2D patients. https://drks.de/search/en/trial/DRKS00014287, identifier DRKS00014287.

Teaching Video NeuroImage: Pupil-Sparing Infranuclear Third Nerve Palsy Pattern Caused by a Mesencephalic Stroke.

A 27-year-old obese woman, a smoker, presented diplopia. She showed ptosis, impaired adduction, supraduction, and infraduction of the left eye with pupil-sparing (figure, A–C and video 1). Brain MRI showed restricted diffusion in the left midbrain, revealing ischemia (figure, D–F). Pupil-sparing third nerve palsy is usually associated with microvascular diabetic ischemia of central fibers in the cisternal segment, but is also related to partial fascicular lesions in brainstem stroke, ophthalmoplegic migraine, and, rarely, aneurysm. Although microvascular and brainstem ischemia have a better prognosis, regardless of pupillary involvement, the investigation is important for secondary stroke prevention, particularly in young patients, as in this case.1,2

C-Fiber Loss as a Possible Cause of Neuropathic Pain in Schwannomatosis.

Schwannomatosis is the third form of neurofibromatosis and characterized by the occurrence of multiple schwannomas. The most prominent symptom is chronic pain. We aimed to test whether pain in schwannomatosis might be caused by small-fiber neuropathy. Twenty patients with schwannomatosis underwent neurological examination and nerve conduction studies. Levels of pain perception as well as anxiety and depression were assessed by established questionnaires. Quantitative sensory testing (QST) and laser-evoked potentials (LEP) were performed on patients and controls. Whole-body magnetic resonance imaging (wbMRI) and magnetic resonance neurography (MRN) were performed to quantify tumors and fascicular nerve lesions; skin biopsies were performed to determine intra-epidermal nerve fiber density (IENFD). All patients suffered from chronic pain without further neurological deficits. The questionnaires indicated neuropathic symptoms with significant impact on quality of life. Peripheral nerve tumors were detected in all patients by wbMRI. MRN showed additional multiple fascicular nerve lesions in 16/18 patients. LEP showed significant faster latencies compared to normal controls. Finally, IENFD was significantly reduced in 13/14 patients. Our study therefore indicates the presence of small-fiber neuropathy, predominantly of unmyelinated C-fibers. Fascicular nerve lesions are characteristic disease features that are associated with faster LEP latencies and decreased IENFD. Together these methods may facilitate differential diagnosis of schwannomatosis.

Structural Nerve Remodeling at 3-T MR Neurography Differs between Painful and Painless Diabetic Polyneuropathy in Type 1 or 2 Diabetes.

Background The pathophysiologic mechanisms underlying painful symptoms in diabetic polyneuropathy (DPN) are poorly understood. They may be associated with MRI characteristics, which have not yet been investigated. Purpose To investigate correlations between nerve structure, load and spatial distribution of nerve lesions, and pain in patients with DPN. Materials and Methods In this prospective single-center cross-sectional study, participants with type 1 or 2 diabetes volunteered between June 2015 and March 2018. Participants underwent 3-T MR neurography of the sciatic nerve with a T2-weighed fat-suppressed sequence, which was preceded by clinical and electrophysiologic tests. For group comparisons, analysis of variance or the Kruskal-Wallis test was performed depending on Gaussian or non-Gaussian distribution of data. Spearman correlation coefficients were calculated for correlation analysis. Results A total of 131 participants (mean age, 62 years ± 11 [standard deviation]; 82 men) with either type 1 (n = 45) or type 2 (n = 86) diabetes were evaluated with painful (n = 64), painless (n = 37), or no (n = 30) DPN. Participants who had painful diabetic neuropathy had a higher percentage of nerve lesions in the full nerve volume (15.2% ± 1.6) than did participants with nonpainful DPN (10.4% ± 1.7, P = .03) or no DPN (8.3% ± 1.7; P < .001). The amount and extension of T2-weighted hyperintense nerve lesions correlated positively with the neuropathy disability score (r = 0.37; 95% confidence interval [CI]: 0.21, 0.52; r = 0.37; 95% CI: 0.20, 0.52, respectively) and the neuropathy symptom score (r = 0.41; 95% CI: 0.25, 0.55; r = 0.34; 95% CI: 0.17, 0.49, respectively). Negative correlations were found for the tibial nerve conduction velocity (r = -0.23; 95% CI: -0.44, -0.01; r = -0.37; 95% CI: -0.55, -0.15, respectively). The cross-sectional area of the nerve was positively correlated with the neuropathy disability score (r = 0.23; 95% CI: 0.03, 0.36). Negative correlations were found for the tibial nerve conduction velocity (r = -0.24; 95% CI: -0.45, -0.01). Conclusion The amount and extension of T2-weighted hyperintense fascicular nerve lesions were greater in patients with painful diabetic neuropathy than in those with painless diabetic neuropathy. These results suggest that proximal fascicular damage is associated with the evolution of painful sensory symptoms in diabetic polyneuropathy. © RSNA, 2019 Online supplemental material is available for this article.

Somatotopic Fascicular Lesions of the Brachial Plexus Demonstrated by High-Resolution Magnetic Resonance Neurography.

The aim of this study was to evaluate whether high-resolution brachial plexus (BP) magnetic resonance neurography (MRN) is capable of (1) distinguishing patients with compressive neuropathy or noncompressive plexopathy from age- and sex-matched controls, (2) discriminating between patients with compressive neuropathy and noncompressive plexopathy, and (3) detecting spatial lesion patterns suggesting somatotopic organization of the BP. Thirty-six patients (50.9 ± 12.7 years) with clinical symptoms, nerve conduction studies, and needle electromyography findings suggestive of brachial plexopathy and 36 control subjects matched for age and sex (50.8 ± 12.6 years) underwent high-resolution MRN of the BP. Lesion determination and localization was performed by 2 blinded neuroradiologists at the anatomical levels of the plexus trunks and cords. By applying defined criteria of structural plexus lesions on high-resolution MRN, all patients were correctly rated as affected, whereas 34 of 36 controls were correctly rated as unaffected by independent and blinded reading from 2 neuroradiologists with overall good to excellent interrater reliability. In all cases, plexopathies with a compressive etiology (n = 12) were correctly distinguished from noncompressive plexopathies with inflammatory origin (n = 24). Pathoanatomical contiguity of lesion from trunk into cord level allowed recognition of distinct somatotopical patterns of fascicular involvement, which correlated closely with the spatial distribution of clinical symptoms and electrophysiological data. Brachial plexus MRN is highly accurate for differentiating patients with symptomatic plexopathy from healthy controls and for distinguishing patients with compressive neuropathy and noncompressive plexopathy. Furthermore, BP MRN revealed evidence for somatotopic organization of the BP. Therefore, as an addition to functional information of electrodiagnostic studies, anatomical information gained by BP MRN may help to improve the efficiency and accuracy of patient care.

Klinische Indikationen hochauflösender MRT-Diagnostik des peripheren Nervensystems

Peripheral neuropathies are common and diagnostically often challenging disorders. Difficulties particularly exist in lesion localization and recognition of complex spatial lesion patterns. Medical history taking, neurological examination, neurophysiological tests and nerve ultrasonography represent the gold standard in the diagnosis of peripheral nerve lesions but have known methodical limitations. The use of 3Tesla magnetic resonance neurography (MRN) is an additional diagnostic imaging tool recently developed for the high-resolution visualization of long segments of peripheral nerves. Reasonable clinical indications for MRN are exemplarily presented. Using MRN a direct visualization and thus precise localization of focal and non-focal peripheral nerve lesions of various origins can be achieved with high spatial resolution down to the anatomical level of nerve fascicles. Using MRN large anatomical areas of the peripheral nervous system (PNS) can be covered in asingle examination session, spatial nerve lesion patterns can be evaluated and the underlying causes can often be detected. The MRN is avaluable supplement to the diagnostic work-up of the PNS, especially in cases that cannot be clarified with standard diagnostic methods. Evaluation of the spatial nerve lesion pattern gives additional information on the origin of the underlying disease. Reasonable indications for MRN are the assessment of proximal nerve structures including the brachial and lumbosacral nerve plexi, the clarification of inconclusive diagnostic results, preoperative, postoperative and posttraumatic assessments, the identification of fascicular nerve lesions and the differential diagnosis of an alleged somatoform disorder.

Schwannoma of the Upper Extremity: Retrospective Analysis of 17 Cases

Schwannoma or neurilemmoma is a benign peripheric nerve tumor that usually presents as a slow growing single lesion; it has origin in Schwann cells proliferation. Although it represents a small percentage of the benign tumors of the upper arm, it is the most frequent of neural origin. We present a retrospective study of upper limb schwannomas; our aim is establish the appropriate preoperative approach, to recognise the efficiency of the treatment and the pos-operative follow-up. Review of 17 patients treated between 2007 and 2014 with upper limb schwannoma and characterization as to age, gender, location in the upper limb, signs and symptoms, pre-operative studies, histologic diagnosis and postoperative surveillance. In four of them the schwannoma was localized on the arm, three on the forearm, four on the wrist and 6 on the hand or fingers. We proceed to careful microsurgical dissection in a bloodless field to optimize the functional final result. The enucleation without fascicular lesion was achieved in 12 patients. In five patients we performed the excision of the fascicles involved by the mass. Nine patients developed paresthesias in the immediate postoperative period, with five of them improving in 12 months. One patient presented motor deficit of the radial nerve with partial recover at 12 monts. Schwannomas are rare tumours with well circumscribed morphology. Occasionally it appears in upper limb. The preoperative diagnosis is rarely, so normally the diagnosis is established only after excision and histologic study. Schwannoma should be considered as a diagnostic hypothesis when evaluating subcutaneous nodes associated with neurologic symptoms. It is important to query the presence of paresthesias and perform the Tinel sign, both typical of this condition. Imagiological exams have a scarce contribute in the diagnosis. To improve the final result, the preoperative study must be insightful, being advisable to consider the benefits of the surgery compared to the potential iatrogenic damage to the nerve.

Posterior interosseous neuropathy: Supinator syndrome vs fascicular radial neuropathy.

Objective:To investigate the spatial pattern of lesion dispersion in posterior interosseous neuropathy syndrome (PINS) by high-resolution magnetic resonance neurography.Methods:This prospective study was approved by the local ethics committee and written informed consent was obtained from all patients. In 19 patients with PINS and 20 healthy controls, a standardized magnetic resonance neurography protocol at 3-tesla was performed with coverage of the upper arm and elbow (T2-weighted fat-saturated: echo time/repetition time 52/7,020 milliseconds, in-plane resolution 0.27 × 0.27 mm2). Lesion classification of the radial nerve trunk and its deep branch (which becomes the posterior interosseous nerve) was performed by visual rating and additional quantitative analysis of normalized T2 signal of radial nerve voxels.Results:Of 19 patients with PINS, only 3 (16%) had a focal neuropathy at the entry of the radial nerve deep branch into the supinator muscle at elbow/forearm level. The other 16 (84%) had proximal radial nerve lesions at the upper arm level with a predominant lesion focus 8.3 ± 4.6 cm proximal to the humeroradial joint. Most of these lesions (75%) followed a specific somatotopic pattern, involving only those fascicles that would form the posterior interosseous nerve more distally.Conclusions:PINS is not necessarily caused by focal compression at the supinator muscle but is instead frequently a consequence of partial fascicular lesions of the radial nerve trunk at the upper arm level. Neuroimaging should be considered as a complementary diagnostic method in PINS.

Multifocal nerve lesions and LZTR1 germline mutations in segmental schwannomatosis.

Schwannomatosis is a genetic disorder characterized by the occurrence of multiple peripheral schwannomas. Segmental schwannomatosis is diagnosed when schwannomas are restricted to 1 extremity and is thought to be caused by genetic mosaicism. We studied 5 patients with segmental schwannomatosis through microstructural magnetic resonance neurography and mutation analysis of NF2, SMARCB1, and LZTR1. In 4 of 5 patients, subtle fascicular nerve lesions were detected in clinically unaffected extremities. Two patients exhibited LZTR1 germline mutations. This appears contrary to a simple concept of genetic mosaicism and suggests more complex and heterogeneous mechanisms underlying the phenotype of segmental schwannomatosis than previously thought. Ann Neurol 2016;80:625-628.

Relationship Between the Idiopathic Anterior Interosseous Nerve Palsy and “Hourglass-like Fascicular Constriction”: Level 4 Evidence

An hourglass-like fascicular constriction, which is a focal fascicular lesion observed at one or a few places in one or a few fascicles of a peripheral nerve trunk, and usually affects the anterior interosseous nerve (AIN) or posterior interosseous nerve, is improved with the relief of symptom. Seven consecutive patients who were diagnosed with idiopathic AIN palsy based on clinical findings and had hourglass-like fascicular constrictions in the AIN revealed by the ultrasonographic examination were included. We used the high-resolution device with a 14-6 MHz linear probe, and observed nerve fascicles in the median nerve trunk in a transverse and longitudinal fashions around the site of tenderness at the elbow joint level confirming the presence of fascicular constriction. The age at the time of diagnosis ranged from 19 to 56 years old. The duration between onset of symptoms and ultrasonographic examination ranged from 7 days to 8 months, and the duration between examination and operation ranged from 3 days to 1 month. All but one case took interfascicular neurolysis, and we followed up all cases clinically and ultrasonographically every one month. At the time of examination, we calculated constriction ratio, which was obtained by the division of the involved fascicular diameter at the constriction by that at the proximal non-constricted site. The number of constrictions ranged from one to eight, and all constrictions revealed ultrasonographically were confirmed intraoperatively. In the five cases with the operative treatment, recovery from paralysis began from 3 weeks to four months after surgery, and was completed (M0 to M4 or M5) five to seven months after surgery. Postoperative ultrasonography revealed the constrictions subsided. The other one treated operatively got little recovery (M0 to M2) at 10 months after surgery, and the severe constriction still remained. In the one conservative treated case, the paralysis began to recover at 9 months and recovered completely (M0 to M5) at 14 months after the onset. On the ultrasonographic examination, its constriction incompletely subsided. The hourglass-like fascicular constriction subsided with the relief of the paralysis both in the operatively and conservatively treated cases. The cause of constricitons is still unknown, however, it may play a significant role on this type of paralysis.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

MR Neurography: Diagnostic Imaging in the PNS.

The diagnostic work-up of peripheral neuropathies is often challenging and is mainly based on a combination of clinical and electrophysiological examinations. One of the most important difficulties is the accurate determination of the lesion site (lesion localization), lesion extension, and spatial lesion dispersion, which all represent essential diagnostic information crucial for finding the correct diagnosis and hence an adequate therapeutic approach. A typical pitfall in the conventional diagnostic reasoning is the differentiation between a distal, complete cross-sectional nerve lesion and a more proximally located, fascicular nerve lesion. Magnetic resonance neurography (MRN) has been proven to be capable of improving the diagnostic accuracy by providing direct, noninvasive visualization of nerve injury with high structural resolution even reaching the anatomical level of single nerve fascicles (fascicular imaging) and at the same time with large anatomical coverage. It is also feasible to detect structural nerve damage earlier and with higher sensitivity than gold-standard nerve conduction studies. The purpose of this study is to review the literature for current developments and advances in MRN for the precise spatial detection of nerve lesions in focal and non-focal disorders of the peripheral nervous system.

Peripheral nerves and plexus: imaging by MR-neurography and high-resolution ultrasound.

The purpose of this study is to review advances in magnetic resonance (MR)-neurography and nerve-ultrasound for the precise visualization and localization of nerve lesions not only in nerve trauma or mass lesions, but also in entrapment-related and spontaneously occurring intrinsic neuropathies. These advances may improve the understanding and classification of peripheral neuropathies. Diagnostic studies of MR-neurography and high-resolution ultrasound in entrapment-neuropathies consistently report accurate determination and localization of symptomatic nerve entrapment. Additionally, the longitudinal sampling of nerve-T2-signal over larger areas of coverage has become technically feasible. With this approach, more complex patterns of spatial lesion dispersion in nonfocal neuropathies could be observed with reliable lesion image contrast at the level of individual nerve fascicles. Imaging detection of fascicular lesions allows for more accurate localization, because fascicular lesion types represent a specific pitfall for clinical-electrophysiological examinations. Fascicular hypoechogenicity of high-resolution ultrasound is the correlate of nerve-T2-signal lesions, but contrast is inferior and difficult to quantify. Therefore, nerve enlargement remains the main diagnostic criterion in high-resolution ultrasound. Diffusion-tensor-MR-neurography provides quantitative estimates of fiber structure, which were shown to correlate with aging and focal entrapment. High-resolution nerve imaging with extended anatomical coverage is feasible and improves the topographic description of spatial lesion dispersion which is particularly relevant for the discrimination between focal and nonfocal neuropathies.

High-Resolution Ultrasonographic Evaluation of “Hourglass-like Fascicular Constriction” in Peripheral Nerves: A Preliminary Report

An hourglass-like constriction is a focal fascicular lesion observed in one or a few places in one or a few fascicles of a peripheral nerve trunk, and usually affects the anterior interosseous (AIN) or posterior interosseous (PIN) nerve. Constrictions have previously been discovered only by surgical exploration, and have been unable to be recognized on pre-operative imaging. We encountered some cases in which the lesion was able to be diagnosed pre-operatively by high-resolution ultrasonography; these findings were then confirmed intra-operatively. Five consecutive cases were included in this study. In three cases with constrictions revealed on pre-operative ultrasound, the findings were confirmed intra-operatively. In the remaining two cases in which no constrictions were detected pre-operatively, no constriction was revealed intra-operatively. High-resolution ultrasonography may play a significant role in the diagnosis of hourglass-like constrictions, and may thus lead to significant changes in treatment strategies for AIN and PIN palsy.

Sciatic Nerve Injury Related to Hip Replacement Surgery: Imaging Detection by MR Neurography Despite Susceptibility Artifacts

Sciatic nerve palsy related to hip replacement surgery (HRS) is among the most common causes of sciatic neuropathies. The sciatic nerve may be injured by various different periprocedural mechanisms. The precise localization and extension of the nerve lesion, the determination of nerve continuity, lesion severity, and fascicular lesion distribution are essential for assessing the potential of spontaneous recovery and thereby avoiding delayed or inappropriate therapy. Adequate therapy is in many cases limited to conservative management, but in certain cases early surgical exploration and release of the nerve is indicated. Nerve-conduction-studies and electromyography are essential in the diagnosis of nerve injuries. In postsurgical nerve injuries, additional diagnostic imaging is important as well, in particular to detect or rule out direct mechanical compromise. Especially in the presence of metallic implants, commonly applied diagnostic imaging tests generally fail to adequately visualize nervous tissue. MRI has been deemed problematic due to implant-related artifacts after HRS. In this study, we describe for the first time the spectrum of imaging findings of Magnetic Resonance neurography (MRN) employing pulse sequences relatively insensitive to susceptibility artifacts (susceptibility insensitive MRN, siMRN) in a series of 9 patients with HRS procedure related sciatic nerve palsy. We were able to determine the localization and fascicular distribution of the sciatic nerve lesion in all 9 patients, which clearly showed on imaging predominant involvement of the peroneal more than the tibial division of the sciatic nerve. In 2 patients siMRN revealed direct mechanical compromise of the nerve by surgical material, and in one of these cases indication for surgical release of the sciatic nerve was based on siMRN. Thus, in selected cases of HRS related neuropathies, especially when surgical exploration of the nerve is considered, siMRN, with its potential to largely overcome implant related artifacts, is a useful diagnostic addition to nerve-conduction-studies and electromyography.

Anterior interosseous nerve syndrome

Objective:We sought to determine lesion sites and spatial lesion patterns in spontaneous anterior interosseous nerve syndrome (AINS) with high-resolution magnetic resonance neurography (MRN).Methods:In 20 patients with AINS and 20 age- and sex-matched controls, MRN of median nerve fascicles was performed at 3T with large longitudinal anatomical coverage (upper arm/elbow/forearm): 135 contiguous axial slices (T2-weighted: echo time/repetition time 52/7,020 ms, time of acquisition: 15 minutes 48 seconds, in-plane resolution: 0.25 × 0.25 mm). Lesion classification was performed by visual inspection and by quantitative analysis of normalized T2 signal after segmentation of median nerve voxels.Results:In all patients and no controls, T2 lesions of individual fascicles were observed within upper arm median nerve trunk and strictly followed a somatotopic/internal topography: affected were those motor fascicles that will form the anterior interosseous nerve further distally while other fascicles were spared. Predominant lesion focus was at a mean distance of 14.6 ± 5.4 cm proximal to the humeroradial joint. Discriminative power of quantitative T2 signal analysis and of qualitative lesion rating was high, with 100% sensitivity and 100% specificity (p < 0.0001). Fascicular T2 lesion patterns were rated as multifocal (n = 17), monofocal (n = 2), or indeterminate (n = 1) by 2 independent observers with strong agreement (kappa = 0.83).Conclusion:It has been difficult to prove the existence of fascicular/partial nerve lesions in spontaneous neuropathies using clinical and electrophysiologic findings. With MRN, fascicular lesions with strict somatotopic organization were observed in upper arm median nerve trunks of patients with AINS. Our data strongly support that AINS in the majority of cases is not a surgically treatable entrapment neuropathy but a multifocal mononeuropathy selectively involving, within the main trunk of the median nerve, the motor fascicles that continue distally to form the anterior interosseous nerve.

Hemangioendothelioma

Hemangioendothelioma is the term used to name those vascular neoplasms that show a borderline biological behavior, intermediate between entirely benign hemangiomas and highly malignant angiosarcomas. Although originally spindle cell hemangioendothelioma was proposed as a specific clinicopathologic variant of hemangioendothelioma, currently, it is considered as an entirely benign lesion, and thus, the name spindle cell hemangioma seems to be the most accurate for this lesion. Authentic hemangioendotheliomas involving the skin and soft tissues include papillary intralymphatic angioendothelioma (also known as Dabska tumor), retiform hemangioendothelioma, kaposiform hemangioendothelioma, epithelioid hemangioendothelioma, pseudomyogenic hemangioendothelioma (also known as epithelioid sarcoma-like hemangioendothelioma), and composite hemangioendothelioma. Each of these neoplasms exhibit characteristic histopathologic features. The most characteristic finding of papillary intralymphatic hemangioendothelioma consists of papillary tufts, with a central hyaline core lined by hobnail-like endothelial cells protruding into the lumina. Retiform hemangioendothelioma is an infiltrative neoplasm composed of elongated arborizing vessels, arranged in an anastomosing pattern that resembles that of the rete testis, and lined by a single layer of hobnail-like endothelial cells that protrude within the narrow lumina. Kaposiform hemangioendothelioma is composed of several solid poorly circumscribed nodules, and each nodule is composed of a mixture of small capillaries and solid lobules of endothelial cells arranged in a glomeruloid pattern. A frequent finding consists of the presence of areas of lymphangiomatosis adjacent to the solid nodules. Epithelioid hemangioendothelioma is composed of cords, strands, and solid aggregates of round, oval, and polygonal cells, with abundant pale eosinophilic cytoplasm, vesicular nuclei, and inconspicuous nucleoli, embedded in a fibromyxoid or sclerotic stroma. Many neoplastic cells exhibit prominent cytoplasmic vacuolization as an expression of primitive vascular differentiation. Pseudomyogenic hemangioendothelioma is a poorly circumscribed, fascicular lesion with infiltrative borders composed of round or oval neoplastic cells, with vesicular nuclei and inconspicuous nucleoli, and ample homogeneous eosinophilic cytoplasm, giving them a rhabdomyoblastic appearance. Finally, composite hemangioendothelioma is the term used to name locally aggressive vascular neoplasms of low-grade malignancy showing varying combinations of benign, low-grade malignant, and high-grade malignant vascular components. From the immunohistochemical point of view, proliferating cells of all hemangioendotheliomas express a lymphatic endothelial cell immunophenotype. Most hemangioendotheliomas are low-grade vascular neoplasms, with a tendency to recur locally and a low metastatic potential, mostly to regional lymph nodes. Epithelioid hemangioendothelioma, especially large lesions and those located in deep soft tissues, seems to have a more aggressive biological behavior.

Cranial nerves 3,4 and 6: from brainstem to orbit

AbstractPurpose To review the pertinent anatomy of the ocular motor cranial nerves in correlation with their clinical presentationMethods didactic lecture and cassResults The nucleus of the oculomotor nerve (CN3) is composed of several subnuclei. The central caudal subnucleus innervates the levator palpebrae bilaterally. Fibers from the superior rectus subnucleus decussate and innervate the SR muscle of the contralateral eye. Axonal fascicles from each subnucleus remain topographically arranged as they traverse the midbrain. Autonomic fibers (pupil and accommodation) orient dorsomedially in the peripheral nerve as it exits the peduncles of the ventral midbrain. The clinical presentation of a nuclear, fascicular and peripheral lesion of CN3 are distinctive and localizing. The trochlear nerve (CN4) is the smallest cranial nerve yet has the longest pathway. It is susceptible during closed head injury. The abducens nerve (CN6) exits the ventral pons and ascends the clivus to reach the cavernous sinus. It is prone to injury with changes in intracranial pressure. Lesions of the clivus can also cause bilateral abducens palsy.Conclusion Understanding the anatomic pathway of the ocular motor nerves can help focus the etiology and location of the lesion. Commercial interest

Accumulation of non-compressive fascicular lesions underlies NF2 polyneuropathy

A distinct polyneuropathy (PNP) syndrome affects up to 66 % of patients with neurofibromatosis II (NF2). Whether this is primarily a diffuse PNP or due to single, surgically amenable mass lesions has not yet been conclusively demonstrated. We aimed to solve this question by investigating the pathomorphological MR imaging correlate of this rare disorder. Eight patients with NF2-PNP were characterized by clinical examination, electrophysiological studies, and genetic analysis. All patients additionally underwent extended peripheral nerve imaging by a novel protocol of large-coverage high-resolution MRI. Quantitative analyses were performed by separately evaluating cross-sectional images, and by categorizing lesions into non-compressive fascicular microlesions (<2 mm), intermediate lesions (2-5 mm), and compressive macrolesions (>5 mm). The predominant imaging findings were non-compressive fascicular microlesions and intermediate lesions. Proximal-to-distal cumulative lesion burden of these lesions correlated strongly with the severity of clinical symptoms of NF2-PNP. In contrast, compressive macrolesions were not found at all in several symptomatic extremities. We conclude that proximal-to-distal accumulation of non-compressive fascicular lesions instead of compressive mass lesions predominantly underlies the clinical manifestation and severity of NF2-associated PNP. Diagnostic management may now be assisted by large-coverage high-resolution imaging of plexus and peripheral nerves. Additionally, the results underscore the feasibility of this new method, which may open up new diagnostic and investigative possibilities for other disseminated disorders of the peripheral nervous system.

Hemiataxia aislada como manifestación de infarto lacunar mesencefálico

Lesions of the dento-rubro-thalamo-cortical pathway may cause homolateral or contralateral hemiataxia, depending on whether they are found above or below the decussation which occurs at the level of the inferior colliculus. Most mesencephalic infarctions causing hemiataxia also show oculomotor involvement with nuclear or fascicular lesions of the third cranial nerves. This was not seen in the case we report. We describe the case of a diabetic patient with a permanent right appendicular hemiataxia, without oculomotor involvement, caused by a lacunar infarct shown on MR imaging which was situated in the antero-external part of the left superior mesencephalum. This case helps to clarify the topography of the thalamic radiations of the mesencephalic calotte, including the decussated superior dento-rubro-thalamic pathway to the red nucleus. Involvement of this, situated in the mesencephalic lateral vascular territory causes contralateral hemiataxia.