Reliability of Intra-Retinal Layer Thickness Estimates.

PURPOSE: Measurement of intra-retinal layer thickness using optical coherence tomography (OCT) has become increasingly prominent in multiple sclerosis (MS) research. Nevertheless, the approaches used for determining the mean layer thicknesses vary greatly. Insufficient data exist on the reliability of different thickness estimates, which is crucial for their application in clinical studies. This study addresses this lack by evaluating the repeatability of different thickness estimates. METHODS: Studies that used intra-retinal layer segmentation of macular OCT scans in patients with MS were retrieved from PubMed. To investigate the repeatability of previously applied layer estimation approaches, we generated datasets of repeating measurements of 15 healthy subjects and 13 multiple sclerosis patients using two OCT devices (Cirrus HD-OCT and Spectralis SD-OCT). We calculated each thickness estimate in each repeated session and analyzed repeatability using intra-class correlation coefficients and coefficients of repeatability. RESULTS: We identified 27 articles, eleven of them used the Spectralis SD-OCT, nine Cirrus HD-OCT, two studies used both devices and two studies applied RTVue-100. Topcon OCT-1000, Stratus OCT and a research device were used in one study each. In the studies that used the Spectralis, ten different thickness estimates were identified, while thickness estimates of the Cirrus OCT were based on two different scan settings. In the simulation dataset, thickness estimates averaging larger areas showed an excellent repeatability for all retinal layers except the outer plexiform layer (OPL). CONCLUSIONS: Given the good reliability, the thickness estimate of the 6mm-diameter area around the fovea should be favored when OCT is used in clinical research. Assessment of the OPL was weak in general and needs further investigation before OPL thickness can be used as a reliable parameter.

Peripheral Nerve Ultrasound in Small Fiber Polyneuropathy.

Routine nerve conduction studies are normal in patients with small fiber neuropathy (SFN), and a definitive diagnosis is based on skin biopsy revealing reduced intra-epidermal nerve fiber density (IENFD). In large fiber polyneuropathy, ultrasound (US) parameters indicate enlargement in cross-sectional area (CSA). This study was aimed at determining if similar changes in large fibers on US are apparent in patients with SFN. Twenty-five patients with SFN diagnosed by reduced IENFD and 25 age- and body mass index (BMI)-matched healthy controls underwent US studies of sural and superficial peroneal sensory nerves. The mean CSA of the sural nerve in SFN patients was 3.2 ± 0.8 mm(2), and in controls, 2.7 ± 0.6 mm(2) (p < 0.0070), and this was independent of sex. There was no difference in the thickness-to-width ratio or echogenicity of the nerves. US of the sural nerve in patients diagnosed with small fiber neuropathy reveals an enlarged cross-sectional area similar to that in large fiber polyneuropathy.

Retinal nerve fiber layer and macular thinning in systemic lupus erythematosus: an optical coherence tomography study comparing SLE and neuropsychiatric SLE.

OBJECTIVE: Due to the lack of reliable biomarkers in diagnosing and monitoring neuropsychiatric systemic lupus erythematosus (NPSLE), the aim of this study was to examine the utility of measurements obtained through spectral domain optical coherence tomography (SD-OCT) as a biomarker for NP involvement in SLE. METHODS: Retinal nerve fiber layer (RNFL) and macula scans were performed using SD-OCT on 15 NPSLE patients, 16 SLE patients without NP symptoms (non-NP SLE), and 16 healthy controls. Macular volume and thickness of the central macula and peripapillary RNFL were compared between the groups and to scores on two validated cognitive tests. RESULTS: NPSLE patients did not differ significantly from non-NP SLE patients in retinal thickness or macular volume. However, SLE patients as a whole showed significant RNFL and macular thinning compared to controls. Scores on the Trail Making Test B, a test of complex attention, showed significant correlation to temporal superior and temporal inferior RNFL thickness. CONCLUSION: Our results demonstrate RNFL thinning in SLE, and confirm the previous finding of high incidence of abnormal brain scans in SLE. These findings suggest that OCT measurements may be indicative of neurodegeneration in SLE and may be a useful biomarker for early cognitive impairment in SLE.

Optical coherence tomography in patients with Chiari I malformation.

BACKGROUND/AIMS: To evaluate optic nerve head with spectral domain optical coherence tomography (OCT) in patients with Chiari I malformation (CMI) compared to healthy controls. METHODS: Cross-sectional study. OCT of the optic nerve head of 22 patients with CMI and 22 healthy controls was quantitatively analyzed. The healthy controls were matched for age and sex with the study population. Mean retinal nerve fiber layer (RNFL) thickness was calculated for both eyes; the mean thickness value was also registered for each quadrant and for each subfield of the four quadrants. RESULTS: CMI patients showed a reduction of the RNFL thickness in both eyes. This reduction was more statistically significant (P < 0.05) for the inferior quadrant in the right eye and in each quadrant than nasal one in the left eye. CONCLUSION: A distress of the retinal nerve fibers could explain the observed reduction of the RNFL thickness in patients with CMI; in our series the reduction of the RNFL thickness seems lower when CMI is associated with syringomyelia.

Lamina cribrosa microarchitecture in normal monkey eyes part 1: methods and initial results.

PURPOSE: To introduce quantitative postmortem lamina cribrosa (LC) microarchitecture (LMA) assessment and characterize beam diameter (BD), pore diameter (PD), and connective tissue volume fraction (CTVF) in 21 normal monkey eyes. METHODS: Optic nerve heads (ONHs) underwent digital three-dimensional (3D) reconstruction and LC beam segmentation. Each beam and pore voxel was assigned a diameter based on the largest sphere that contained it before transformation to one of twelve 30° sectors in a common cylinder. Mean BD, PD, and CTVF within 12 central and 12 peripheral subsectors and within inner, middle, and outer LC depths were assessed for sector, subsector, and depth effects by analysis of variance using general estimating equations. Eye-specific LMA discordance (the pattern of lowest connective tissue density) was plotted for each parameter. RESULTS: The ranges of mean BD, PD, and CTVF were 14.0 to 23.1 µm, 20.0 to 35.6 µm, and 0.247 to 0.638, respectively. Sector, subsector, and depth effects were significant (P < 0.01) for all parameters except subsector on CTVF. Beam diameter and CTVF were smaller and PD was larger within the superior-temporal (ST) and inferior-temporal (IT) sectors (P < 0.05). These differences were enhanced within the central versus peripheral subsectors. Beam diameter and CTVF were larger and PD was smaller (P < 0.05) within the middle LC layer. Lamina cribrosa microarchitecture discordance most commonly occurred within the ST and IT sectors, varied by eye, and generally diminished as CTVF increased. CONCLUSIONS: Our data support previous characterizations of diminished connective tissue density within the ST and IT ONH regions. The clinical importance of eye-specific LMA discordance warrants further study.

Distinct types of white matter changes are observed after anterior temporal lobectomy in epilepsy.

Anterior temporal lobectomy (ATL) is commonly adopted to control medically intractable temporal lobe epilepsy (TLE). Depending on the side of resection, the degree to which Wallerian degeneration and adaptive plasticity occur after ATL has important implications for understanding cognitive and clinical outcome. We obtained diffusion tensor imaging from 24 TLE patients (12 left) before and after surgery, and 12 matched controls at comparable time intervals. Voxel-based analyses were performed on fractional anisotropy (FA) before and after surgery. Areas with postoperative FA increase were further investigated to distinguish between genuine plasticity and processes related to the degeneration of crossing fibers. Before surgery, both patient groups showed bilateral reduced FA in numerous tracts, but left TLE patients showed more extensive effects, including language tracts in the contralateral hemisphere (superior longitudinal fasciculus and uncinate). After surgery, FA decreased ipsilaterally in both ATL groups, affecting the fornix, uncinate, stria terminalis, and corpus callosum. FA increased ipsilaterally along the superior corona radiata in both left and right ATL groups, exceeding normal FA values. In these clusters, the mode of anisotropy increased as well, confirming fiber degeneration in an area with crossing fibers. In left ATL patients, pre-existing low FA values in right superior longitudinal and uncinate fasciculi normalized after surgery, while MO values did not change. Preoperative verbal fluency correlated with FA values in all areas that later increased FA in left TLE patients, but postoperative verbal fluency correlated only with FA of the right superior longitudinal fasciculus. Our results demonstrate that genuine reorganization occurs in non-dominant language tracts after dominant hemisphere resection, a process that may help implement the inter-hemispheric shift of language activation found in fMRI studies. The results indicate that left TLE patients, despite showing more initial white matter damage, have the potential for greater adaptive changes postoperatively than right TLE patients.

Greater attenuation of retinal nerve fiber layer thickness in Alzheimer's disease patients.

Thinning of retinal nerve fiber layer (RNFL) may reflect neurodegeneration of the central nervous system, which has been reported as part of the neuropathogenesis of Alzheimer's disease (AD). Specifically, AD patients have thinner RNFL as compared to age-matched normal controls. However, whether reduction of RNFL over time can predict those at higher risk to develop cognitive deterioration remains unknown. We therefore set out a prospective clinical investigation to determine both the reduction of RNFL thickness and the deterioration of cognitive function over a period of 25 months in 78 participants (mean age 72.31 ± 3.98 years, 52% men). The participants were categorized as stable participants whose cognitive status remained unchanged (n = 60) and converted participants whose cognitive status deteriorated, which was diagnosed by DSM-VI (for AD) and Petersen's definition (for mild cognitive impairment) (n = 18). Here we show for the first time that the converted participants had greater reduction of RNFL thickness than the stable participants. Specifically, the reduction in the thickness of the inferior quadrant RNFL in the converted participants was greater than that in stable participants [-11.0 ± 12.8 (mean ± standard deviation) µm versus 0.4 ± 15.7 µm, p = 0.009]. These data showed that greater reduction in the inferior quadrant of RNFL thickness might indicate a higher risk for the old adults to develop cognitive deterioration. These findings have established a system to embark on a larger scale study to further test whether changes in RNFL thickness can serve as a biomarker of AD.

Evaluation of relationship between retinal nerve fiber layer thickness progression and visual field progression in patients with glaucoma.

PURPOSE: To evaluate the capability of optical coherence tomography (OCT), retinal nerve fiber layer (RNFL) thickness, and visual field (VF) measurements in glaucoma progression detection. METHODS: The study examined 62 eyes of 37 glaucoma patients observed over a 3-year period. All eyes underwent at least four serial RNFL measurements performed by Cirrus OCT, with the first and last measurements separated by at least 3 years. VF testing was performed by using the Swedish interactive threshold algorithm (SITA) Standard 30-2 program of the Humphrey field analyzer (HFA) on the same day as the RNFL imaging. Both serial RNFL thicknesses and VF progression were assessed by the guided progression analysis (GPA) software program. RNFL thickness progression was evaluated by event analysis. Total deviation (TD) in the superior or inferior hemifield was also examined. RESULTS: A total of 295 OCT scans and 295 VFs were analyzed. Five eyes exhibited progression by OCT only and 8 eyes exhibited progression by VF GPA only. When the analysis was based on the combined measurement findings, progression was noted in 6 eyes. The average of the progressive hemifield TD at baseline for combined RNFL and VF progression was -3.21±1.38 dB, while it was -2.17±1.14 dB for RNFL progression and -9.12±3.75 dB for VF progression. The average of the progressive hemifield TD indicated a significant advancement of VF progression as compared to RNFL progression (P=0.002). CONCLUSIONS: When a mild VF defect is present, OCT RNFL thickness measurements are important in helping discern glaucoma progression.

Differentiation of optic disc edema from optic nerve head drusen with spectral-domain optical coherence tomography.

BACKGROUND: To assess the efficacy of quantitative analysis of the optic nerve head and peripapillary retinal nerve fiber layer (RNFL) with the spectral-domain optical coherence tomography (SD-OCT) in differentiating optic disc edema (ODE) from optic nerve head drusen (ONHD). METHODS: Prospective clinical study. Twenty-five eyes of 25 ODE patients (group 1), 25 eyes of 25 ONHD patients (group 2), and 25 eyes of 25 healthy subjects were included. The thickness of the peripapillary RNFL, the thickness of the subretinal hyporeflective space (SHYPS), the area of the SHYPS, the horizontal length of the optic nerve head, and the angle between the temporal RNFL and the optic nerve head (α-angle) were evaluated with SD-OCT. RESULTS: The mean RNFL thickness was significantly greater in group 1 when compared with group 2 and control group (P < 0.001). The receiver operating characteristic curve areas for temporal and nasal RNFL thicknesses in differentiating group 1 and group 2 were 0.819 and 0.851, respectively (for temporal RNFL thickness >101.5 µm: sensitivity 92%, specificity 65%; for nasal RNFL thickness >74.5 µm: sensitivity 92%, specificity 47%). The mean SHYPS thickness, SHYPS area, and degree of the α-angle were greater in group 1 when compared with group 2 (P < 0.05). For the SHYPS thickness >464 µm: 85% sensitivity and 60% specificity; for the SHYPS area >811 µm: 85% sensitivity and 89% specificity; and for the α-angle >141°: 77% sensitivity and 95% specificity were obtained. CONCLUSION: The quantitative analysis of the optic nerve head and peripapillary RNFL with SD-OCT can provide useful data in differentiating ODE from ONHD.

[Measurement of retinal nerve fiber layer thickness in Leber hereditary optic neuropathy by optical coherence tomography].

OBJECTIVE: To evaluate retinal nerve fiber layer (RNFL) thickness in patients and unaffected carriers of Leber hereditary optic neuropathy (LHON) by optical coherence tomography (OCT). METHODS: This case-control study enrolled 42 LHON maternal family members with mitochondrial DNA G11778A mutation and 100 normal volunteers. RNFL thickness was measured by Stratus OCT in each participant. Mean RNFL thickness of each quadrant, as well as 360° average were calculated and compared in normal controls, LHON carries and LHON patients. RESULTS: Among LHON maternal family members, 15 cases were unaffected carriers who were subgrouped as normal-fundus-appearing carriers (10 cases) and preclinical carriers (5 cases). Twenty seven LHON patients included 9, 5, and 13 cases in the early, advancing and advanced stages, respectively. Normal fundus-appearing carriers showed normal RNFL thickness of each quadrant and 360° average. Preclinical carriers and early-staged patients showed no significant difference in RNFL thickness of each quadrant and 360° average (P = 0.138 to 0.645), yet both showed thicker RNFL in temporal, superior and inferior quadrant, as well as 360° average, if compared with normal controls (P = 0.000 to 0.018). Compared with normal controls, preclinical carriers and early-staged patients, advancing LHON patients showed thinner RNFL in temporal and inferior quadrant, as well as 360° average (P = 0.000 to 0.005). Advanced LHON patients showed thinner RNFL in each quadrant and 360° average, compared with normal controls, LHON carriers, and advancing cases (P = 0.000 to 0.037). CONCLUSIONS: RNFL thickness in LHON patients and unaffected carriers was characterized by OCT in this study, which would improve the understanding of the natural course of LHON.

Retinal nerve fiber layer and macular inner retina measurements by spectral domain optical coherence tomograph in Indian eyes with early glaucoma.

PURPOSE: To compare the diagnostic abilities of peripapillary retinal nerve fiber layer (RNFL) and macular inner retina (MIR) measurements by spectral domain optical coherence tomography (SD-OCT) in Indian eyes early glaucoma. METHODS: In an observational, cross-sectional study, 125 eyes of 64 normal subjects and 91 eyes of 59 early glaucoma patients underwent RNFL and MIR imaging with SD-OCT. Glaucomatous eyes had characteristic optic nerve and RNFL abnormalities and correlating visual field defects and a mean deviation of better than or equal to -6 dB on standard automated perimetry. Areas under the receiver operating characteristic curves (AUC), sensitivities at a fixed specificity and likelihood ratios (LRs) were estimated for all RNFL and MIR parameters. RESULTS: The AUCs for the RNFL parameters ranged from 0.537 for the temporal quadrant thickness to 0.821 for the inferior quadrant RNFL thickness. AUCs for the MIR parameters ranged from 0.603 for the superior minus inferior MIR thickness average to 0.908 for ganglion cell complex focal loss volume (GCC-FLV). AUC for the best MIR parameter (GCC-FLV) was significantly better (P<0.001) than that of the best RNFL parameter (inferior quadrant thickness). The sensitivities of these parameters at high specificity of 95%, however, were comparable (52.7% vs58.2%). Evaluation of the LRs showed that outside normal limits results of most of the RNFL and MIR parameters were associated with large effects on the post-test probability of disease. CONCLUSION: MIR parameters with RTVue SD-OCT were as good as the RNFL parameters to detect early glaucoma.

Small fibre dysfunction, microvascular complications and glycaemic control in type 1 diabetes: a case-control study.

AIMS/HYPOTHESIS: The aim of this study was to determine the influence of microvascular disease on C-fibre function in patients with type 1 diabetes of moderate duration. METHODS: The axon-reflex flare area induced on the dorsum of the foot by local skin heating to 47 °C was measured with a laser Doppler imager (LDI) in sex-, age- and height-matched groups with type 1 diabetes, with and without microvascular disease (MV+ and MV-, respectively) and in healthy controls (HC). Each group consisted of 24 individuals and all were free from clinical neuropathy (neuropathy disability score <3 and Toronto clinical neuropathy score <5). RESULTS: LDI flare (LDIflare) was reduced in MV+ compared with HC (5.1 ± 1.8 vs 10.0 ± 3.1 cm², p < 0.0001) and MV- groups (9.9 ± 2.9 cm², p < 0.0001). MV- and HC groups did not differ. There was no difference in diabetes duration between MV- and MV+ groups (17.5 ± 5.7 and 20.1 ± 5.2 years, p = 0.21) nor current HbA(1c) (MV- 8.0 ± 1.2% [64 ± 10 mmol/mol]; MV+ 8.0 ± 0.9% [64 ± 9 mmol/mol], p = 0.53); neither variable correlated with flare size. In contrast, duration-averaged HbA(1c) was higher in the MV+ group (8.6 ± 0.9% [70 ± 9 mmol/mol] vs 7.6 ± 0.6% [60 ± 7 mmol/mol], p < 0.001) and correlated with LDIflare size (r = -0.50, p < 0.001). Triacylglycerols were higher in MV+ compared with MV- (1.23 ± 0.121 vs 0.93 ± 0.7 mmol/l, p = 0.04), but other metabolic variables did not differ between the groups. CONCLUSIONS/INTERPRETATION: We have shown that glycaemic burden and the presence of microvascular complications are associated with small fibre dysfunction in type 1 diabetes.

Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics.

Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3×3×3µm(3) resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3°×3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n=5; 29-62years). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were used to assess visibility and size distribution of individual RNFBs. In one subject, we reimaged the same RNFBs twice over a 7month interval and compared bundle width and thickness between the two imaging sessions. Lastly we compared images of an arcuate RNFL defect acquired with UHR-AO-OCT and commercial OCT (Heidelberg Spectralis). Individual RNFBs were distinguishable in all subjects at 3° retinal eccentricity in both cross-sectional and en face views (width: 30-50µm, thickness: 10-15µm). At 6° retinal eccentricity, RNFBs were distinguishable in three of the five subjects in both views (width: 30-45µm, thickness: 20-40µm). Width and thickness RNFB measurements taken 7months apart were strongly correlated (p<0.0005). Mean difference and standard deviation of the differences between the two measurement sessions were -0.1±4.0µm (width) and 0.3±1.5µm (thickness). UHR-AO-OCT outperformed commercial OCT in terms of clarity of the microscopic retina. To our knowledge, these are the first measurements of RNFB cross section reported in the living human eye.

Retinal nerve fibre layer and macular thickness in amblyopia as measured by spectral-domain optical coherence tomography.

BACKGROUND/AIMS: To study peripapillary retinal nerve fibre layer (RNFL) and macular thickness in amblyopia using high-definition spectral-domain optical coherence tomography (SD-OCT) and to compare the results with available literature using the time-domain modality. METHODS: This was a prospective institutional study of patients ≥ 6 years of age with unilateral amblyopia (strabismic or anisometropic) and non-amblyopic anisometropia. RNFL and macular thicknesses were measured using SD-OCT and compared between fellow eyes. RESULTS: The mean age was 20 (± 12) years; 45 patients had amblyopia: 14 strabismic and 31 anisometropic. 20 patients had non-amblyopic anisometropia. The mean macular thickness was significantly increased in the amblyopic (273.8 µm) vs fellow eyes (257.9 µm), p=0.001. This difference remained significant in the anisometropic group (p=0.002) but not the strabismic group. The mean RNFL thickness was similar in amblyopic (95.4 µm) and fellow eyes (94.0 µm). Similar results were obtained regardless of the level of visual acuity, age or refractive error. In the control group of non-amblyopic anisometropia, the interocular difference did not reach statistical significance. CONCLUSIONS: Central macular thickness was significantly increased in anisometropic amblyopia using SD-OCT. Anisometropia alone did not produce such a difference, which points to a possible correlation between amblyopia and the development of the retinal layers.

[Significance of optic disc topography and retinal nerve fiber layer thickness measurement by spectral-domain OCT in diagnosis of glaucoma].

OBJECTIVE: To study the significance of optic disc tomography and retinal nerve fiber layer (RNFL) thickness measurement by spectral-domain optical coherence tomography (OCT) in the diagnosis of glaucoma. METHODS: It was a noninterventional, observational study. The optic disc topographic parameters and total and regional RNFL thickness were measured by RTVue OCT in 60 normal eyes and 97 glaucomatous eyes. One-way analysis of variance was used to compare the parameters above mentioned between normal and glaucomatous groups. The area under the receiver operating characteristic curve (AUC) and the sensitivity at 80% specificity were used to assess the ability of each testing parameter in the differentiation between normal and glaucoma eyes. RESULTS: There were statistically significant differences in all RTVue OCT measurement parameters (F = 1.024, P = 0.596;F = 36.519, 54.464, 27.659, 36.176, 20.562, 63.833, 30.031, 54.652, 98.146, 78.705, 99.839, 43.728, 75.720, 45.709, 39.380, 33.590, 66.887, 78.335, 45.485;P = 0.000) except disc area. The average RNFL thickness in normal, early, moderate and advanced glaucomatous eyes was 109.950, 93.313, 80.374 and 65.570 µm, respectively. Among the eight regions around the optic disc, the thickest RNFL was located at the inferotemporal (150.066 µm) and superotemporal (146.285 µm) regions in normal eyes, and the superotemporal (108.569, 103.420 and 88.708 µm in early, moderate and advanced glaucomatous eyes, respectively) and inferotemporal (108.201, 102.830 and 86.369 µm in early, moderate and advanced glaucomatous eyes, respectively) regions in glaucomatous eyes. Both in normal and glaucomatous eyes, the thinnest RNFL was located at the nasal and temporal regions, respectively. For optic disc topographic parameters, the highest AUC was vertical cup/disc ratio (AUC = 0.762, 0.946 and 0.988 in early, moderate and advanced glaucomatous eyes, respectively), and the sensitivity at 80% specificity was 62.2%, 76.5% and 99.2% in early, moderate and advanced glaucomatous eyes, respectively. For RNFL thickness, the highest AUC was superotemporal region RNFL thickness (AUC = 0.915) and the sensitivity at 80% specificity was 89.5% in early glaucomatous eyes. The highest AUC was inferior average RNFL thickness (AUC = 0.967) and the sensitivity at 80% specificity was 94.1% in moderate glaucomatous eyes. The highest AUC was average RNFL thickness (AUC = 0.985) and the sensitivity at 80% specificity was 99.2% in advanced glaucomatous eyes. Among the eight regions around the optic disc, RNFL thickness of region ST (AUC = 0.915, 0.926 and 0.966 in early, moderate and advanced glaucomatous eyes, respectively) achieved the highest AUC. RNFL thicknesses of the nasal and temporal regions showed the lowest AUCs. CONCLUSIONS: RTVue OCT shows fair discriminating ability in distinguishing normal from glaucomatous eyes. RTVue OCT is a useful equipment for the diagnosis of glaucoma.

Correlations between radiographic, magnetic resonance and histological examinations on the degeneration of human lumbar intervertebral discs.

CONTEXT AND OBJECTIVE: There is controversy regarding which imaging method is best for identifying early degenerative alterations in intervertebral discs. No correlations between such methods and histological finds are presented in the literature. The aim of this study was to correlate the thickness of intervertebral discs measured on simple radiographs with the degree of degeneration seen on magnetic resonance images and the histological findings relating to nerve ends inside the discs. DESIGN AND SETTING: Cross-sectional correlation study on the lumbar spines of human cadavers, at Universidade Federal de São Paulo (Unifesp), São Paulo, Brazil. METHODS: Ten lumbar spinal columns were extracted from human cadavers and subjected to magnetic resonance imaging and simple radiography. They were classified according to the degree of disc degeneration seen on magnetic resonance, and the thickness of the discs was measured on radiographs. The intervertebral discs were then extracted, embedded in paraffin and analyzed immunohistochemically with protein S100, and the nerve fibers were counted and classified. RESULTS: No correlation was observed between the thickness of the intervertebral discs and the degree of degeneration seen on magnetic resonance images. Only the uppermost lumbar discs (L1/L2 and L2/L3) presented a correlation between their thickness and type I and IV nerve endings. CONCLUSION: Reduced disc thickness is unrelated to increased presence of nerve ends in intervertebral discs, or to the degree of disc degeneration.

Ultrasound-guided interventional procedures in pain medicine: a review of anatomy, sonoanatomy, and procedures. Part II: axial structures.

There is a growing trend in using ultrasonography in pain medicine as evident by the plethora of published reports. Ultrasound(US) provides direct visualization of various soft tissues and real-time needle advancement and avoids exposing both the health care provider and the patient to the risks of radiation. The US machine is more affordable and transferrable than fluoroscopy, computed tomography scan,or magnetic resonance imaging machine. In a previous review, we discussed the challenges and limitations of US, anatomy, sonoanatomy, and techniques of interventional procedures of peripheral structures. In the present review, we discuss the anatomy, sonoanatomy, and US-guided techniques of interventional pain procedures for axial structures and review the pertinent literature.

[Evaluation of factors associated with variability in retinal nerve fiber layer thickness in myopic juveniles aged 7-18 years].

OBJECTIVE: To evaluate the relationship between retinal nerve fiber layer thickness(RNFLT)measured by optical coherence tomography (OCT) and age, spherical equivalent (SE), axial length, and gender in myopic juveniles. METHODS: Cross-sectional observational study. One hundred and fifty-four juveniles (age range, 7-18 years) underwent ophthalmic examinations. Peripapillary Fast RNFL scans were performed by Stratus OCT with a nominal diameter of 3.46 mm centered on the optic disc on one randomly selected eye of each subject. Axial length was measured by A-ultrasound. The effects of several factors (age, SE, axial length, gender and eye) on RNFLT were investigated in univariate and multivariate stepwise regression analyses. RESULTS: The mean global RNFLT (x(-) ± s) was (114.106 ± 11.473) µm. The RNFLT was thickest superiorly (145.468 ± 19.064) µm and inferiorly (138.091 ± 20.464) µm, thinner temporally (94.396 ± 18.544) µm, and thinnest nasally (78.558 ± 16.981) µm. Both global and superior peripapillary RNFLT had no significant relationship with age (r = 0.129, 0.014; P > 0.05), SE (r = 0.006, 0.123; P > 0.05), axial length (r = -0.067, -0.141; P > 0.05), gender (r = -0.095, 0.025; P > 0.05) and laterality (r = -0.148, 0.095; P > 0.05). In multivariate stepwise regression analyses, there was significant inverse linear correlation between temporal RNFLT and SE (r = -0.465, P < 0.05). There was significant inverse linear correlation between nasal RNFLT and axial length and laterality (r = -0.327, P < 0.05). There was significant inverse linear correlation between inferior RNFLT and axial length (r = -0.276, P < 0.05), and direct linear correlation between inferior RNFLT and age (r = 0.276, P < 0.05). CONCLUSIONS: When we assess the RNFLT in myopic juveniles, we should consider the influence of age, refraction, axial length, spherical equivalent and laterality comprehensively.

Ultrasound-guided interventional procedures in pain medicine: a review of anatomy, sonoanatomy, and procedures: part I: nonaxial structures.

Application of ultrasound in pain medicine is a rapidly growing medical field in interventional pain management. Ultrasound provides direct visualization of various soft tissues and real-time needle advancement and avoids exposing both the health care provider and the patient to the risks of radiation. The machine itself is more affordable than a fluoroscope, computed tomography scan, or magnetic resonance imaging machine. In the present review, we discuss the challenges and limitations of ultrasound-guided procedures for pain management, anatomy, and sonoanatomy of selected pain management procedures and the literature on those selected procedures.