Length Of Nerve Research Articles

Investigating animal models of optic neuropathy: An accurate method for optic nerve and chiasm dissection in mice

BackgroundNumerous disorders affecting the optic nerve require histological examination of whole length optic nerves and chiasm. Most methods employed to study the histopathology of the optic nerves in animal models of human diseases involve resection of a short retrobulbar section after eye globe exenteration, commonly obtained in mice. This approach might affect the morphology of the optic nerve, thus limiting accurate identification of pathological changes in the tissue. Some histological studies were performed on longer or more posterior parts of the anterior visual pathway included the chiasm. However, an accurate replicable protocol for such whole length (eye globe to chiasm) dissection is currently unavailable in published literature. New MethodHere we describe a protocol for dissecting the whole length of the optic nerves and chiasm through a craniotomy incision. ResultsWe describe in detail the stages necessary for exposing the optic nerves, the chiasm and the optic tracts, and for detaching them with minimal traction. Comparison with Existing MethodThe existing replicable method provide only a sample of the retrobulbar optic nerve and the sample might be affected by traction. Our protocol provides a whole length specimen of the optic nerve and chiasm without concern of traction artifacts. ConclusionsWe present a simple and straightforward approach to isolate the complete anterior visual pathway in the mouse for histopathological evaluation.

Characteristics of Corneal Endotheliitis among Different Viruses by in Vivo Confocal Microscopy

ABSTRACT Objectives: To explore the cellular morphological characteristics and changes in corneal endotheliitis among different viruses by in vivo confocal microscopy (IVCM).Methods: Corneal confocal images of 44 eyes of 44 patients with HSV, VZV, CMV and EBV corneal endotheliitis were studied retrospectively. Corneal confocal images of 44 normal eyes were used as controls.Results: The pathogens included cytomegalovirus (n = 20), herpes simplex virus (n = 8), varicella zoster virus (n = 10), and Epstein Barr virus (n = 6). There were no differences in the evaluated structures among the different viruses except for the lengths of the subbasal nerves and Langerhans cell densities. Deviations in endothelial cell layers were not significant among different viruses except for owl’s eye morphology.Conclusion: ICVM can assist in diagnosing endotheliitis. The results demonstrate that changes in the cornea were not different among the various viruses except for owl’s eye morphology, the lengths of the subbasal nerves and Langerhans cell densities

Correlations between the trigeminal nerve microstructural changes and the trigeminal-pontine angle features.

Morphological and microstructural changes of the trigeminal nerve due to neurovascular compression (NVC) have been reported in primary trigeminal neuralgia (PTN) patients. This investigation was to examine the relationship between the trigeminal-pontine angle and nerve microstructural changes. Twenty-five patients underwent microvascular decompression (MVD) for trigeminal neuralgia, and 25 age- and sex-matched controls were studied. The two groups underwent high-resolution three-dimensional MRI and diffusion tensor imaging (DTI). Bilateral trigeminal-pontine angle, cross-sectional area of cerebellopontine angle (CPA) cistern, and the length of trigeminal nerve were evaluated. The mean values of fractional anisotropy and apparent diffusion coefficient at the site of NVC were also measured. Correlation analyses were performed for the trigeminal-pontine angle and the diffusion metrics (FA and ADC) in PTN patients. The mean trigeminal-pontine angle and FA value on the affected side was significantly smaller than the unaffected side and the control group (p < 0.001), while the mean ADC value was significantly increased (p < 0.01). When taking the conflicting vessel types into consideration, the angle affected by the superior cerebellar artery (SCA) was statistically sharper than when affected by other vessels (p < 0.01). However, there were no significant changes in the area of the CPA cistern or the length of the trigeminal nerve between the groups. Correlation analyses showed that the trigeminal-pontine angle was positively correlated with FA and negatively correlated with ADC. A sharp trigeminal-pontine angle may increase the chance of NVC and exacerbate nerve degeneration, which may be one of the supplementary factors that contribute to the pathogenesis of trigeminal neuralgia.

Infectious ocular motor neuropathies.

Describe the range of infectious causes of ocular motor neuropathies, from common presentations to unusual manifestations of diseases less frequently seen in the developed world. Provide information on recent developments in diagnostic testing for pathogens that may cause ocular motor neuropathies. Antigen detection in serum or CSF has improved the diagnosis of cryptococcal disease. Cartridge PCR testing for tuberculosis has increased diagnostic accuracy, though tuberculous meningitis remains difficult to diagnose. Rapid, multiplex PCR and unbiased sequencing allow for diagnosis of a wider range of organisms. Infectious ocular motor neuropathies can occur anywhere along the length of cranial nerves III, IV, and VI. Characteristic clinical findings and imaging can be used to localize infections. Infectious causes may have characteristic clinical, laboratory, or imaging findings, but must still be carefully separated from inflammatory or neoplastic conditions.

In idiopathic cubital tunnel syndrome, ulnar nerve excursion and instability can be reduced by repairing Osborne's ligament after simple decompression.

Osborne's modified decompression involves repairing Osborne's ligament beneath the ulnar nerve after simple decompression for idiopathic cubital tunnel syndrome. In this retrospective interrupted time series, 31 patients underwent modified simple decompression and 20 patients underwent conventional simple decompression. In the modified simple decompression group, the ulnar nerve length was measured at operation in full elbow flexion and extension before and after repair of Osborne's ligament. Ulnar nerve instability during elbow motion was measured using ultrasonography before operation and at 12 months after operation. In patients treated by modified simple decompression, the ulnar nerve length in full elbow flexion reduced significantly after repair of Osborne's ligament. At 12 months after surgery, the grade of ulnar nerve instability was lower in the modified simple decompression group than in the conventional simple decompression group. The clinical outcomes did not differ significantly between the groups at 24 months after operation. Level of evidence: III.

Novel Method of Double Innervated Free Gracilis Muscle Functional Transfer for Facial Reanimation

PURPOSE: Dynamic facial reanimation is the gold standard treatment for a paralyzed face. The use of cross-face nerve graft (CFNG) in combination with the masseteric nerve to innervate free gracilis muscle has been reported in various configurations, with the goal of providing both spontaneity from the CFNG and strong innervation from the masseteric nerve. We report a novel modification to the existing nerve configuration, with presentation of outcomes of our case series. METHODS: A total of 8 patients received free gracilis muscle transfer using the new double innervation method between September 2014 and December 2017. The CFNG, which was performed 9 months prior, was sutured in an end-to-end fashion to the obturator nerve. The ipsilateral masseter nerve was coapted to a nerve graft obtained from extra length of obturator nerve obtained during the harvest of the gracilis muscle. This nerve graft was then sutured in an end-to-side fashion to the sural nerve graft proximal to the end-to-end obturator coaptation (Figure will be provided during presentation). Video analysis was performed on preoperative and all postoperative follow-up. Two independent experienced raters performed Terzis 5 stages classification on the videos. Time to smile with biting down and time to natural smile were also assessed. RESULT: All patients recover smile function with teeth clenching (average, 7.5 months; range, 3–12). Two patients did not recover smile function at 4 and 8 months follow-up, but achieved smile at their 10 and 12 months follow-up. Seven of 8 patients recover spontaneous smile by average of 8.4 months (range, 7–12), with 1 patient having no function after 12 months of follow-up. Average follow-up time was 22 months. Based on the Terzis reanimation grading, 4 patients achieved moderate result, 2 achieved good result, and 2 achieved excellent result. CONCLUSION: Our new novel method of dual gracilis innervation represents a viable technique that does not risk denervation of the gracilis muscle, and provide good spontaneous emotional smile and esthetic symmetry. We hypothesize that placing the masseter nerve at a disadvantage by using the extra nerve graft which requires the signal to go through 3 anastomosis, the CFNG has more time to provide a stronger signal without being taken over by the masseter.

Optic Nerve Tortuosity and Globe Proptosis in Normal and Glaucoma Subjects.

The purpose of this study was to assess the difference in optic nerve tortuosity during eye movements and globe proptosis between primary open angle glaucoma and normal subjects using orbital magnetic resonance imaging (MRI). Ten Chinese subjects matched for ethnicity and refractive errors were recruited, including 5 normal controls and 5 patients with primary open angle glaucoma. All subjects underwent MRI to assess their optic nerves and globes for 3 eye positions: primary gaze, adduction, and abduction. Optic nerve tortuosity (optic nerve length divided by the distance between 2 ends) and globe proptosis (maximum distance between the cornea and interzygomatic line) were measured from MRI images. In adduction, the tortuosity of normal eyes was significantly larger than that of the glaucomatous eyes. Optic nerve tortuosity in adduction in the control and glaucoma groups were 1.004±0.003 (mean±SD) and 1.001±0.001, respectively (P=0.037). Globe proptosis (primary gaze) in glaucoma subjects (19.14±2.11 mm) was significantly higher than that in control subjects (15.32±2.79 mm; P=0.046). In this sample, subjects with glaucoma exhibited tauter optic nerves and more protruding eye globes compared with normal eyes. This may impact optic nerve head deformations in anatomically predisposed patients.

Surgical anatomy of the ovine sural nerve for facial nerve regeneration and reconstruction research

The lack of a clinically relevant animal models for research in facial nerve reconstruction is challenging. In this study, we investigated the surgical anatomy of the ovine sural nerve as a potential candidate for facial nerve reconstruction, and performed its histological quantitative analysis in comparison to the buccal branch (BB) of the facial nerve using cadaver and anesthetized sheep. The ovine sural nerve descended to the lower leg along the short saphenous vein. The length of the sural nerve was 14.3 ± 0.5 cm. The distance from the posterior edge of the lateral malleolus to the sural nerve was 7.8 ± 1.8 mm. The mean number of myelinated fibers in the sural nerve was significantly lower than that of the BB (2,311 ± 381vs. 5,022 ± 433, respectively. p = 0.003). The number of fascicles in the sural nerve was also significantly lower than in the BB (10.5 ± 1.7 vs. 21.3 ± 2.7, respectively. p = 0.007). The sural nerve was grafted to the BB with end-to-end neurorrhaphy under surgical microscopy in cadaver sheep. The surgical anatomy and the number of fascicles of the ovine sural nerve were similar of those reported in humans. The results suggest that the sural nerve can be successfully used for facial nerve reconstruction research in a clinically relevant ovine model.

Progression and Pathology of Traumatic Optic Neuropathy From Repeated Primary Blast Exposure.

Indirect traumatic optic neuropathy (ITON) is a condition that is often associated with traumatic brain injury and can result in significant vision loss due to degeneration of retinal ganglion cell (RGC) axons at the time of injury or within the ensuing weeks. We used a mouse model of eye-directed air-blast exposure to characterize the histopathology of blast-induced ITON. This injury caused a transient elevation of intraocular pressure with subsequent RGC death and axon degeneration that was similar throughout the length of the optic nerve (ON). Deficits in active anterograde axon transport to the superior colliculus accompanied axon degeneration and first appeared in peripheral representations of the retina. Glial area in the ON increased early after injury and involved a later period of additional expansion. The increase in area involved a transient change in astrocyte organization independent of axon degeneration. While levels of many cytokines and chemokines did not change, IL-1α and IL-1β increased in both the ON and retina. In contrast, glaucoma shows distal to proximal axon degeneration with astrocyte remodeling and increases in many cytokines and chemokines. Further, direct traumatic optic neuropathies have a clear site of injury with rapid, progressive axon degeneration and cell death. These data show that blast-induced ITON is a distinct neuropathology from other optic neuropathies.

The rabbit brachial plexus as a model for nerve injury and repair Part 1: Anatomic study of the biceps and triceps innervation.

Animal models can be helpful in evaluating new surgical strategies for brachial plexus reconstruction. While several groups have already used the rabbit brachial plexus to model injury, reports conflict in anatomic detail and do not identify a nerve-muscle pair to measure motor function recovery after reconstruction. The purpose of the current study is to describe the innervations of the biceps and triceps muscles in rabbits, which are both amenable to study in brachial plexus injury models. Thirteen rabbits weighing 2-2.5 kg were anesthetized. Six rabbits were sacrificed and dissected using loupe and microscope magnification to understand the overall morphology of the brachial plexus. Seven rabbits underwent electrophysiologic investigation. A bipolar nerve stimulator was used to systematically stimulate the roots, trunks and divisions, and nerve branches of the rabbit brachial plexus and compound muscle action potential was used to record muscle response. Nerve length and width measurements were not recorded. Roots contributing to the brachial plexus were C5, C6, C7, C8, and T1. In contrast to other anatomical studies, T2 did not contribute to the brachial plexus. The triceps was innervated by the radial nerve, which received contributions from C6 (1.6 mA), C7 (1.9 mA), C8, and T1 (12.2 mA).The biceps had dual innervation (proximally and distally). The proximal branch received contributions from C6 (3.5 mA) and C7 (5mA). The distal portion was innervated by a branch from the median nerve, which received innervation from C6, C7, C8, and T1. The overall structure of rabbit brachial plexus is described and innervation of the biceps and triceps is described in detail. This anatomic investigation will form the basis of a future brachial plexus model of injury and repair.

The Effects of Aging on Corneal and Ocular Surface Homeostasis in Mice.

Aging is a risk factor for dry eye disease. The aim of this study was to investigate if aging is associated with a range of signs of dry eye disease, including tear hyperosmolarity, reduced nerve density, and increased dendritic cell number, in mice. Healthy C57BL/6 female mice, aged 2 months (young, n = 10) and 22 months (aged, n = 11) were used. Clinical assessments included corneal sensitivity (Cochet-Bonnet esthesiometry), tear secretion (Phenol red thread test), tear film osmolarity (TearLab osmometer), and corneal thickness (optical coherence tomography). The sum length of the corneal superficial terminals and sub-basal nerves, density of vertical nerve projections, and density and tree area of resident epithelial dendritic cells, were assessed using immunofluorescence and confocal microscopy. Aged mice had significantly higher tear secretion, lower corneal sensitivity, and a thicker corneal stroma but thinner epithelium. There was no significant intergroup difference for tear osmolarity. Aged mice showed a significantly lower sum length of nerves in the superficial terminals and sub-basal plexus, relative to young mice. Dendritic cell density and morphology were similar in both groups. In mice, aging is associated with higher tear secretion and corneal epithelial thinning, together with lower corneal nerve density and sensitivity. However, aging was not significantly associated with changes to tear osmolarity or dendritic cell density or size, despite a significant reduction in total nerve length. These findings demonstrate that aged mice exhibit some changes to ocular surface parameters that parallel the anomalies evident in dry eye disease.

Microsurgical Anatomy of the Central Retinal Artery

The central retinal artery (CRA) has been described as one of the first branches of the ophthalmic artery.It arises medial to the ciliary ganglion and after a sinuous path within the orbital cavity it penetrates the lower surface of the dura mater that covers the optic nerve, approximately 1 cm behind the eyeball. However, the numerous anatomic descriptions that were made of the CRA have been insufficient or unclear in relation to certain characteristics that are analyzed in the present study. An electronic literature search was made in the PubMed database and a cadaver dissection was performed on 11 orbits fixed in formaldehyde. Results were obtained regarding the source, collateral branches, curves, direction, length of the optic nerve, dural perforation site, distance, path and relations, diameter, and area of the central artery of the retina. Our anatomic study innovates in 2 aspects of the CRA: area and curves. Not only was there a simple count of the number of curves, but it also analyzed the angle presented by each of the curves based on photos obtained in high definition, with a digital program to reduce the margin of error. These curvatures of the CRA were classified according to their spatial disposition within the orbital cavity based on a pattern that was easy to understand. Data were obtained from the area of the CRA on the penetration of the CRA into the dural sheath of the optic nerve.

“Undercutting of the corresponding rib”: a novel technique of increasing the length of donor in intercostal to musculocutaneous nerve transfer in brachial plexus injury

Intercostal nerves (ICN) are often utilized as donors for various neurotization procedures in brachial plexus injuries. ICN to musculocutaneous nerve (MCN) transfer is usually a standard in pan brachial plexus injuries, in order to restore flexion at the elbow. A tensionless co-aptation of the donor-recipient nerves often necessitates either a distal dissection of the ICNs where the number of fascicles is rather low or a proximal dissection, often at the cost of dissection of the serratus anterior digitation with a risk of later fibrosis and adhesion. We report two cases of pan brachial plexus injuries where ICN-MCN transfer was performed to restore elbow function. These patients underwent clinical and electrodiagnostic evaluation before surgery. We used the standard technique of harvesting ICNs 3-5, with our technical modification of “undercutting of rib” for increasing the donor length. The procedure was applied in two patients with pan brachial plexus injury (mean age = 23). Mean duration since the injury to surgery was ten months. Both patients underwent tensionless anastomosis with a combination of suture and fibrin glue co-aptation. While one patient had some improvement in elbow flexion, another one was under active rehabilitation protocol during follow-up. We found that undercutting of the ribs near serratus digitations can allow mobilization of the ICN from its groove, which in turn lengthens the donor nerve length without violating the serratus anterior digitations and without too anterior dissection of the nerve. It can be a viable option when a tensionless co-aptation at the axilla is otherwise not feasible intraoperatively.

Latissimus Denervation: A Review of Evidence.

Breast reconstruction is becoming an increasingly important and accessible component of breast cancer care. Among the many reconstructive options available, the latissimus dorsi flap has experienced a renewal in popularity because of its favorable properties and outcomes when used for breast reconstruction. However, a limitation unique to latissimus-based reconstruction is inappropriate breast animation postoperatively, due to persistent thoracodorsal innervation of the latissimus dorsi muscle after transfer to the mastectomy site. A comprehensive literature search of PubMed and MEDLINE was conducted for studies investigating the role of thoracodorsal denervation in latissimus-based breast reconstruction. Data on surgical techniques, type of intervention, objective outcome measurements, and patient satisfaction-based outcomes were reported. Additional data included patient sample size, follow-up length, and treatment of thoracodorsal nerve (e.g., resection versus transection and length of transection) when applicable. Sixty-six search results were reviewed for inclusion and nine qualified after exclusion criteria for a total of 361 patients undergoing either unilateral or bilateral latissimus flap reconstruction. Successful thoracodorsal denervation rates were included in most studies and outcomes measurements were heterogeneous. Eight out of nine studies included patient-reported symptoms of breast animation postoperatively. Based on these findings, a systematic approach is presented. We present this review to elucidate successful practices, identify current gaps in knowledge, and offer a systematic approach to this clinical challenge.

Magnetic resonance neurography appearance and diagnostic evaluation of peripheral nerve sheath tumors

Imaging appearances of peripheral nerve sheath tumors by MRI are difficult distinguish from soft-tissue tumors. The objective of this study was to evaluate the feasibility and imaging appearance of high-resolution 3-T magnetic resonance neurography (MRN) of the diagnosis of peripheral nerve sheath tumors (PNSTs) using sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) sequences. We retrospectively evaluated the MRI and 3D Short tau inversion recovery sampling perfection with application-optimized contrasts using varying flip-angle evolutions (3D-STIR SPACE) sequences of 30 patients with PNSTs diagnosed by surgery and pathology. The contrast-enhanced 3D-STIR SPACE images were retrospectively analyzed and evaluated for the visualization of PNSTs. The tumors were evaluated by their number, location, morphology, size, signal intensity and enhancement characteristics. The imaging findings and characteristic signs of conventional MRI scanning and contrast-enhanced 3D-STIR SPACE sequences were compared. In these cases, conventional MRI images display the location, number, shape, size and signal characteristics of the lesions. These tumors were mostly solitary and had a well-defined boundary. Compared to conventional MRI images, imaging appearances including neurogenic origin, length of the peripheral nerves and relation to the nerve of PNSTs on 3D-STIR SPACE images were more accuracy (P < 0.05). Compared to 3D-STIR SPACE images, contrast-enhanced images can more clearly display background suppression of the peripheral nerves. The “split fat” sign and “target” sign were seen in some patients. 3D STIR SPACE sequences demonstrate its significant capacity to diagnostic evaluate and location of PNSTs. This article comprehensively reviews radiologic findings and illustrates the MRN features of PNSTs. 3D-STIR SPACE sequences be used for preoperative evaluation of PNSTs.

Ulnar collateral ligament insufficiency affects cubital tunnel syndrome during throwing motion: a cadaveric biomechanical study

In throwing athletes, cubital tunnel syndrome and insufficiency of the ulnar collateral ligament (UCL) are common pathologic processes of the elbow. The objective of this study was to investigate the effect of UCL tears on ulnar nerve elongation in the simulated throwing position. Eight fresh frozen cadaveric upper limbs were tested at the simulated late cocking to acceleration phase in the throwing motion using an elbow testing system. Elbow valgus laxityand ulnar nerve length and strain under 2 Nm of applied valgus torque (maximum torque in cadaveric elbow) were evaluated. Paired t-tests were used to compare all data between intact UCLs and UCLs after complete transection of the anterior oblique ligament. Linear regression analysis was used to investigate relationships between elbow valgus laxity and ulnar nerve strain. Elbow valgus laxity significantly increased after transection of the UCL. Ulnar nerve length after UCL transection was significantly greater than that in the intact condition at 60° (P = .006) and 90° of elbow flexion (P < .0001). In addition, ulnar nerve strain was positive (increased) at 60° and 90° of elbow flexion. Maximum ulnar nerve strain at 90° of elbow flexion was 3.9% ± 0.9% when the UCL was intact and 6.8% ± 0.7% after transection. UCL transection yielded significant positive correlation between elbow valgus laxity and ulnar nerve strain (P = .006; r = .4714). Increased elbow valgus laxity due to UCL insufficiency may cause elongation of the ulnar nerve and exacerbate cubital tunnel syndrome during the throwing motion.

Innervation of the subscapularis: an anatomic study

BackgroundSuccessful healing of the subscapularis during anatomic total shoulder arthroplasty surgery is critical to optimize functional outcomes and avoid complications. The purpose of this study was to examine the upper and lower subscapularis nerve insertion in relation to the musculotendinous junction to estimate the risk of nerve injury. Our hypothesis was that arm position changes the risks to these nerves when exposing the anterior glenoid.MethodsTwenty cadaveric shoulders were dissected, and the subscapular nerves were identified from the posterior cord of the brachial plexus to the muscle insertion. The nerve length from the origin to the muscle insertion and the distance to the myotendinous junction were measured in various shoulder positions including neutral, external, and internal rotation.ResultsThe mean length of the upper subscapular nerve was 51.4 ± 12.8 mm; that of the lower subscapular nerve was 50.5 ± 14 mm. The mean distance from the insertion of the upper subscapular nerve to the myotendinous junction 53.0 ± 14.7 mm with external rotation, 38.5 ± 9.7 mm with neutral rotation, and 30.0 ± 9.2 mm with internal rotation. The mean distance from the lower subscapular nerve to the myotendinous junction was 44.5 ± 13.8 mm with external rotation, 31.9 ± 9.3 mm with neutral rotation, and 25.4 ± 8.8 mm with internal rotation. The internally rotated position placed these nerves closest to the glenohumeral joint.ConclusionThe upper and lower subscapular nerves insert in the muscle belly close to the myotendinous junction, putting them at risk of iatrogenic injury. Care must be taken to avoid damage with retractor placement in the anterior glenoid neck as these nerves are at risk of compression or torsional injury.

Analysis of morphological measurements of the trigeminal nerve in the linac stereotactic radiosurgery simulation targeting the root entry zone in trigeminal neuralgia

PurposeTo describe the anatomical measurements of the trigeminal nerve in patients with trigeminal neuralgia (TN) during Linac (linear accelerator)-based stereotactic radiosurgery (SRS) simulation, targeting the root entry zone (REZ), with a 30% isodose line tangential to the pons, using 4-mm and 6-mm collimators. MethodsIn this retrospective study, 53 TN patients, who underwent Fiesta sequence scanning prior to any treatment modality, were assessed. Bilateral measurements were obtained from the cisternal segment of the trigeminal nerve, the trigeminal-pontine angle, and the lateral width of the pontine cistern on the Fiesta MRI sequence. Linac-based SRS simulations were estimated with a radiation dosage of 90Gy to 30% isodose line tangential to the pons, with both 4- and 6-mm collimators. Distances from the calculated targets to the pons and the Gasserian ganglion were measured for later analysis. The statistical analysis was performed comparing the affected side against the unaffected side. ResultsRight trigeminal nerve was affected in 36 patients (67.9%), and left one in 17 (32.1%) patients. The mean length of the trigeminal nerve was 9.8mm (range: 4.6–16.8mm) on the affected side, and 10.5mm (range: 5.6–18.4mm) on the unaffected side (p=.02). The mean trigeminal-pontine angle was 12.5° (range: 5.4° to 19.5°) on the affected side, and 10.2° (range: 5.0° to 30.5°) on the unaffected side (p=.01). In the simulations, the distances from the estimated targets to the pons and the Gasserian ganglion were not statistically different between sides. The variation of target-pons and target-ganglion distances was statistically significant on the affected side with the change of collimators (p<.001). ConclusionsIn this anatomical study, significant differences were identified in the length of the affected trigeminal nerve and trigeminal-pontine angle compared to the unaffected side in TN patients in Fiesta sequences prior to surgery or radiosurgery. Significant variation of the target location was found on the REZ between the 4- and 6-collimators during the Linac-based SRS simulations with the estimated radiation dosage of 90Gy and 30% isodose line tangential to the pons.

Long-term corneal subbasal nerve plexus regeneration after laser in situ keratomileusis

To analyze the recovery of the subbasal nerve plexus in corneas treated with laser insitu keratomileusis (LASIK) at least 10years prior compared with nonoperated corneas. Clínica Novovisión, Madrid, Spain. Prospective nonrandomized observational study. Eyes that had LASIK surgery at least 10years before (LASIK group) were compared with nonoperated healthy eyes (control group). The subbasal nerve plexus morphology (main nerves density, nerve length, nerve branches density, grade of nerve tortuosity, and reflectivity) and the dendritic cell density from the confocal images obtained with the Heidelberg Retina Tomograph II were analyzed. The study comprised 47 eyes (27 eyes in the LASIK group and 20 eyes in the control group). The values were significantly lower in the LASIK group compared with the control group in main nerves density (9.15 nerves/mm2±3.46 [SD] versus 11.75±2.86 nerves/mm2; P=.009) and nerve branches density (2.96±1.99 nerves/mm2 versus 5.35±3.05 nerves/mm2; P=.002). No significant differences were found in nerve length, grade of nerve tortuosity, dendritic cell density, or subbasal nerve plexus reflectivity between the two groups. The outcomes suggested that the subbasal corneal nerve plexus did not completely recover its preoperative pattern at least 10years after LASIK. Both main nerves density and nerve branches density continued to be significantly lower compared with virgin corneas after a mean 13-year follow-up, although other parameters of nerve morphology (nerve length, tortuosity, and reflectivity) returned to normal levels.

Sonographic follow-up after endoscopic carpal tunnel release for severe carpal tunnel syndrome: a one-year neuroanatomical prospective observational study

BackgroundEndoscopic carpal tunnel release (ECTR) has been gradually adopted for the treatment of severe carpal tunnel syndrome (CTS). However, perioperative assessment of neuroanatomical parameters of median nerve, which are important determinant of median nerve recovery, has rarely been reported. This one-year prospective study aimed to investigate the natural history of the neuroanatomical morphology of the median nerve after ECTR in severe CTS patients by high-frequency ultrasonography and assess the ability of neuroanatomical measures to quantify morphological recovery of the median nerve after ECTR.MethodsThis study recruited 31 patients (44 wrists) with a definitive diagnosis of severe CTS and underwent ECTR operation. The edema length (EL) of median nerve from the inlet of the carpal tunnel to the proximal wrist was detected on long axis imaging plane and the anteroposterior diameter (D) and cross-sectional area (CSA) at the inlet of the carpal tunnel on short axis imaging plane were detected by high frequency ultrasound. All these metrics were detected at 3 days before surgery and at the 2nd week, 4th week, 3rd month, 6th month and 12th month after surgery separately.ResultsThere was no significant difference of each parameter between the 2-week postoperative (1.914 ± 0.598 cm in EL, 0.258 ± 0.039 cm in D and 0.138 ± 0.015 cm2 in CSA) and 3-days preoperative time points (P-EL =0.250; P-D = 0.125; P-CSA =0.712). From the fourth week to the third month after surgery, the parameters quickly improved. The EL (0.715 ± 0.209 cm), D (0.225 ± 0.017 cm) and CSA (0.117 ± 0.012 cm2) at the 3- month postoperative time points were more reduced than at the fourth week after surgery (P-EL < 0.001; P-D = 0.038; P-CSA =0.014). Thereafter, the neurological anatomy parameters recovered slowly. By the 12-month postoperative time points, the three parameters were neuroanatomically close to normal. Compared to the control group in D (0.213 ± 0.005 cm), there was no difference at the 12-month time point (0.214 ± 0.009 cm, P = 0.939). However, the difference in EL (0.098 ± 0.030 cm vs. 0.016 ± 0.011 cm) and CSA (0.103 ± 0.008 cm2 vs. 0.073 ± 0.005 cm2) between patients and healthy volunteers at the 12-month time point still existed (P-EL < 0.001; P-CSA < 0.001).ConclusionsNeuroanatomical parameters were gradually improved after ECTR surgery. The best time for US follow up is at 3-month postoperative time point for patients who do not show clinical improvement, since at this time the change is the greatest for most CTS patients. This study has been registered in Chinese Clinical Trial Registry: ChiCTR-ROC-17014068 (retrospectively registered 20-12-2017).