Low incidence of true Sternberg's canal defects among lateral sphenoid sinus encephaloceles.

BACKGROUND: Spontaneous sphenoid sinus cerebrospinal fluid (CSF) encephaloceles have been postulated to arise from a persistent Sternberg's canal. However, recent evidence has questioned this embryological etiology. We examined the anatomic location of a series of lateral sphenoid sinus encephaloceles to determine if they corresponded with the location of Sternberg's canal. METHODS: We queried a prospectively acquired database of surgically treated spontaneous CSF leaks and identified those arising from the sphenoidal sinus. Images were reviewed to characterize the leaks with respect to the foramen rotundum (FR) and the vidian canal (VC). Four leak types were classified of which Type I (medial to FR and VC entering nasopharynx) was theoretically located in the precise location of Sternberg's canal. Type II was medial to FR; Type III was lateral to FR; Type IV passed through an enlarged FR into sphenoid sinus. Demographic data were analyzed. RESULTS: Of 103 repaired CSF leaks, 17 arose from the lateral sphenoid sinus. There were no true Type I leaks, 3 Type II leaks, 12 Type III leaks, and 2 Type IV leaks. No differences were found with respect to sphenoid pneumatization, BMI, age, sex, arachnoid pits, or postoperative leak between different types. CONCLUSIONS: No evidence was found to support the existence of a classic Sternberg canal CSF leak, supporting the hypothesis that most sphenoid spontaneous leaks likely occur secondary to chronically elevated ICP. Rare cases may be related to a weakness in the sphenoid wall in the region of Sternberg's canal.

Spontaneous regression of a clival chordoma. Case report.

In this case report, we present a rare and previously unreported case of spontaneous regression of a histologically consistent clival chordoma. At the time of diagnosis, imaging demonstrated a T2 hyperintense and T1 isointense midline skull base mass, centered in the nasopharynx, with scalloping of the ventral clivus consistent with a chordoma measuring 3.1 × 1.9 × 3.0 cm (8.84 cm3). On pre-operative imaging 2 months later, with no intervening therapy, the mass had regressed by 61.7% to a size of 2.3 × 2.1 × 1.4 cm (3.38 cm3). The patient self-administered several herbal supplements and animal oils which may have contributed to tumor regression. The purpose of this report is to document this rare occurrence and provide a comprehensive description of the case details and list of the various medications, herbs, and supplements used prior to this rare event.

Magnetic resonance spectroscopy abnormalities in traumatic brain injury: A meta-analysis.

BACKGROUND AND PURPOSE: Despite traumatic brain injury (TBI) being common, evaluation with imaging remains challenging. Magnetic resonance spectroscopy (MRS) shows promise in detecting changes of brain metabolite concentrations following TBI; however, currently there are only small studies available without conclusive evidence of the technique's efficacy. The purpose of this systematic review and meta-analysis was to evaluate the association between TBI and MRS metabolite changes. MATERIALS & METHODS: A comprehensive literature search was performed looking for studies reporting brain metabolite concentrations in both TBI and control subjects. Included studies reported values for both adult TBI and control subjects. Cumulative and subgroup meta-analyses were performed using a random effects model. RESULTS: The literature search returned an initial 898 manuscripts, of which 36 (which included 748 unique subjects) met study criteria. Cumulatively, NAA/Cr ratios in TBI patients showed a significant decrease as compared to controls (standardized mean deviation [SMD]=-0.88, P<0.0001). When broken into subgroups by severity, the severe and mixed TBI subgroups showed decreases, but the mild TBI (mTBI) subgroup did not. When stratified by time, a significant decrease was seen in the subacute and chronic phases but not the acute phase. Cumulative post-TBI Cho/Cr levels were increased compared to controls (SMD=0.69, P=0.0002). Significant changes were seen in all subgroups except the mild and mixed mTBI subgroups and the acute phase subgroup. CONCLUSION: Current evidence shows that MRS is able to detect changes to metabolites following TBI, but not in patients with mTBI or in the acute stage.

Posterior Lumbar Interbody Fusion with 3D-Navigation Guided Cortical Bone Trajectory Screws for L4/5 Degenerative Spondylolisthesis: 1-Year Clinical and Radiographic Outcomes.

OBJECTIVE: We describe our technique and evaluate clinical and radiographic outcomes for patients undergoing L4/5 posterior lumbar interbody fusion with 3D-navigation guided cortical bone trajectory screws (PLIF-CBT) for grade 1 or 2 degenerative spondylolisthesis with a minimum follow-up time of 12 months. METHODS: A single-institution series of 18 patients was evaluated with data prospectively collected and retrospectively analyzed. Pain and disability scores were collected preoperatively and at a minimum of 12 months postoperatively, including back and bilateral leg pain visual analog scores (VAS) and Oswestry Disability Index (ODI) scores. Radiographic fusion was assessed as complete, partial, or none based on the presence of bridging bones across the disc space, posterior elements, or both. RESULTS: Patients demonstrated statistically significant reductions in back pain VAS (P = 0.0025), leg pain VAS (P < 0.0001), and ODI (P < 0.0001) at a minimum of 12 months postoperatively. Radiographic fusion at an average of 14.9 months postoperatively was available for 16/18 patients, with 6 patients demonstrating fusion (4/6 with complete fusion; 2/6 with partial fusion). There were no instances of intraoperative complications or delayed complications requiring subsequent interventions. CONCLUSIONS: PLIF-CBT can be performed in a safe and reproducible fashion with excellent clinical outcomes at 1 year postoperatively. The outcomes did not correlate with fusion status, which was unexpectedly low at 37.5% without significant hardware abnormalities necessitating reoperations. PLIF-CBT offers several perioperative advantages compared with traditional open PLIF and requires longer-term studies to demonstrate its durability with regard to improvement in clinical pain and radiographic endpoints, including anterior and/or posterior element fusion.

Radiographic and Clinical Outcome of Silicate-substituted Calcium Phosphate (Si-CaP) Ceramic Bone Graft in Spinal Fusion Procedures.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To evaluate the radiographic and clinical outcome of silicate-substituted calcium phosphate (Si-CaP), utilized as a graft substance in spinal fusion procedures. SUMMARY OF BACKGROUND DATA: Specific properties of Si-CaP provide the graft with negative surface charge that can result in a positive effect on the osteoblast activity and neovascularization of the bone. METHODS: This study included those patients who underwent spinal fusion procedures between 2007 and 2011 in which Si-CaP was used as the only bone graft substance. Fusion was evaluated on follow-up CT scans. Clinical outcome was assessed using Oswestry Disability Index, Neck Disability Index, and the visual analogue scale (VAS) for back, leg, neck, and arm pain. RESULTS: A total of 234 patients (516 spinal fusion levels) were studied. Surgical procedures consisted of 57 transforaminal lumbar interbody fusion, 49 anterior cervical discectomy and fusion, 44 extreme lateral interbody fusion, 30 posterior cervical fusions, 19 thoracic fusion surgeries, 17 axial lumbar interbody fusions, 16 combined anterior and posterior cervical fusions, and 2 anterior lumbar interbody fusion. At a mean radiographic follow-up of 14.2±4.3 months, fusion was found to be present in 82.9% of patients and 86.8% of levels. The highest fusion rate was observed in the cervical region. At the latest clinical follow-up of 21.7±14.2 months, all clinical outcome parameters showed significant improvement. The Oswestry Disability Index improved from 45.6 to 13.3 points, Neck Disability Index from 40.6 to 29.3, VAS back from 6.1 to 3.5, VAS leg from 5.6 to 2.4, VAS neck from 4.7 to 2.7, and VAS arm from 4.1 to 1.7. Of 7 cases with secondary surgical procedure at the index level, the indication for surgery was nonunion in 3 patients. CONCLUSIONS: Si-CaP is an effective bone graft substitute. At the latest follow-up, favorable radiographic and clinical outcome was observed in the majority of patients. LEVEL OF EVIDENCE: Level-III.

Anterior Cervical Discectomy and Fusion (ACDF): Comparison Between Zero Profile Implants and Anterior Cervical Plate and Spacer.

INTRODUCTION: Interposition grafts combined with anterior plating currently remain the gold standard for anterior cervical discectomy and fusion. The use of anterior plates increases fusion rates but may be associated with higher rates of postoperative dysphagia. The aim of the current study was to determine the clinical and radiological outcomes following anterior cervical discectomy and fusion (ACDF) using zero-profile anchored spacers versus standard interposition grafts with anterior plating. METHODS: This was a retrospective case series. A total of 53 male and 51 female consecutive patients (164 total operated levels) who underwent ACDF between 2007 and 2011 were included. The mean clinical follow-up was 15.7 ± 1.2 (SEM) months for patients with zero-profile implants and 14.8 ± 2.1 months for patients with conventional ACDF with anterior plating. Patient demographics, operative details, clinical outcomes, complications, and radiographic imaging were reviewed. Dysphagia was determined using the Bazaz criteria. RESULTS: Clinical outcome scores improved in both groups as measured by the modified Japanese Orthopedic Association and Nurick scores. Zero-profile constructs gave rise to significantly less prevertebral soft tissue swelling compared to constructs with anterior plates postoperatively (15.74 ± 0.52 as compared to 20.48 ± 0.85 mm, p < 0.001) and at the latest follow-up (10.88 ± 0.39 mm vs. 13.72 ± 0.67 mm, p < 0.001). There was a significant difference in the incidence of dysphagia at the latest follow-up (1.5% vs. 20%, p=0.001, zero-profile vs. anterior plate, respectively). CONCLUSION: Zero-profile implants lead to functional outcomes similar to standard anterior plate constructs. Avoiding the use of an anterior locking plate may decrease the risk of persistent postoperative dysphagia.

Advanced Imaging for Biopsy Guidance in Primary Brain Tumors.

Accurate glioma sampling is required for diagnosis and establishing eligibility for relevant clinical trials. MR-based perfusion and spectroscopy sequences supplement conventional MR in noninvasively predicting the areas of highest tumor grade for biopsy. We report the case of a patient with gliomatosis cerebri and multifocal patchy enhancement in whom the combination of advanced and conventional imaging attributes successfully guided a diagnostic biopsy.

Three-dimensional volumetric measurements in defining endoscope-guided giant adenoma surgery outcomes.

PURPOSE: Maximum two-dimensional (2D) diameter has been used to define giant pituitary adenoma (GPA) surgery outcomes as has volume using an ellipsoid approximation of volumetrics. Cross sectional length can be measured in several different planes. We sought to compare the accuracy of different 2D cross sectional measurements with the 3D volumetric measurements for predicting GPA surgery outcomes. METHODS: Retrospective analysis was performed on a prospectively collected database. Tumors with >3 cm diameter were identified and classified based on maximal cross sectional measurements in three separate co-axial planes, i.e. transverse (TV), antero-posterior (AP) and cranio-caudal (CC). Volume was calculated using both MRI-guided volumetrics and an ellipsoid approximation (TV × AP × CC/2). Univariate and multivariate analysis was used to evaluate the relationship between cross sectional and volumetric data and extent of resection (EOR). RESULTS: In 62 subjects, median tumor volume using 3D volumetrics was 13.74 cm(3), which was overestimated by 16 % by the ellipsoid calculation (p = 0.0029), particularly for tumors >20 cm(3). Gross total resection (GTR) was 46.7 % and median EOR was 99.57 %. At 22-month follow-up, visual and anterior pituitary functions were stable (90 %) or improved (87 %). Pre-operative tumor volume >10 cm(3) (p = 0.02) and Knosp grade 3-4 (p = 0.04) were independent predictors of EOR. Knosp grade 3-4 (p < 0.0001), TV measurement >4 cm (p = 0.007) and maximum cross sectional length >4 cm (p = 0.04) were predictors of not achieving GTR. Only TV measurement (p = 0.02) predicted permanent diabetes insipidis. The smallest significant thresholds for predicting decreased GTR were TV measurement >25 mm, AP measurement >35 mm and volume >19 cm(3). CONCLUSION: We propose a new volumetric threshold of 20 cm(3) as most accurate for predicting GTR in the EEA era. CC measurement is the least useful predictor. Cavernous sinus invasion remains the best predictor of incomplete resection.

Quantitative Gross and CT measurements of Cadaveric Cervical Vertebrae (C3 - C6) as Guidelines for the Lateral mass screw fixation.

BACKGROUND: Lateral mass screw fixation is the treatment of choice for posterior cervical stabilization. Long or misdirected screws carry a risk of injury to spinal nerve roots or vertebral artery. This study was aimed to assess the gross anatomic and CT measurements of typical cervical vertebrae for the selection of lateral mass screws. METHODS: Dimensions of the articular pillars were measured on 1) Dry cervical vertebrae with Vernier calipers and 2) Multiplanar reformations of CT scans of the same vertebrae with Viewer software package. The data was statistically evaluated. RESULTS: The transverse diameter of the articular pillars with Vernier calipers varied from 6.0 to 15.4 mm (mean=10.5 mm ± 1.5) and on CT scans ranged from 8.2 - 16.1 mm (mean=11.6 mm ± 1.4). The antero-posterior diameter, an estimate of the screw length by Roy-Camille technique varied from 3.9 to 12.7 mm (mean=8.6 mm ± 1.6) by Vernier calipers and from 6.4 to 13.3 mm (mean=9.1 ± 1.2) on CT scans. The oblique AP diameter, an estimate of screw length by Magerl method varied from 10.8 to 20.3 mm (mean=14.9 mm ± 1.8) by Vernier calipers and from 11.4 to 19.3 mm (mean=14.5 mm ± 1.7) on CT. The CT measurements for height, transverse and AP diameter of the articular pillars were 0.5 - 1.0 mm larger than dimensions by Vernier calipers. No statistically significant difference was observed between the caliper and CT measurements for the oblique AP diameter. CONCLUSION: CT measurements of the articular pillars may slightly overestimate the desired screw length selected by spine surgeons when compared to actual anatomy. Although means of the articular pillars correspond to the screw lengths used, substantial number of observations below 10 mm for Roy-Camille trajectory and below 14 mm for Magerl trajectory requires careful preoperative planning and intra-operative confirmation to avoid long/misdirected lateral mass screws.

Endoscope-assisted endonasal versus supraorbital keyhole resection of olfactory groove meningiomas: comparison and combination of 2 minimally invasive approaches.

OBJECTIVE: Although the endonasal endoscopic approach has been applied to remove olfactory groove meningiomas, controversy exists regarding the efficacy and safety of this approach compared with more traditional transcranial approaches. The endonasal endoscopic approach was compared with the supraorbital (eyebrow) keyhole technique, as well as a combined "above-and-below" approach, to evaluate the relative merits of each approach in different situations. METHODS: Nineteen cases were reviewed and divided according to operative technique into 3 different groups: purely endonasal (6 cases); supraorbital eyebrow (microscopic with endoscopic assistance; 7 cases); and combined endonasal endoscopic with either the bicoronal or eyebrow microscopic approach (6 cases). Resection was judged on postoperative MRI using volumetric analysis. Tumors were assessed based on the Mohr radiological classification and the presence of the lion's mane sign. RESULTS: The mean age at surgery was 61.4 years. The mean tumor volume was 19.6 cm(3) in the endonasal group, 33.5 cm(3) in the supraorbital group, and 37.8 cm(3) in the combined group. Significant frontal lobe edema was identified in 10 cases (52.6%). The majority of tumors were either Mohr Grade II (moderate) (42.1%) or Grade III (large) (47.4%). Gross-total resection was achieved in 50% of the endonasal cases, 100% of the supraorbital eyebrow cases with endoscopic assistance, and 66.7% of the combined cases. The extent of resection was 87.8% for the endonasal cases, 100% for the supraorbital eyebrow cases, and 98.9% for the combined cases. Postoperative anosmia occurred in 100% of the endonasal and combined cases and only 57.1% of the supraorbital eyebrow cases. Excluding anosmia, permanent complications occurred in 83.3% of the cases in the endoscopic group, 0% of the cases in the supraorbital eyebrow group, and 16.7% of cases in the combined group (p = 0.017). There were 3 tumor recurrences: 2 in the endonasal group and 1 in the combined group. CONCLUSIONS: The supraorbital eyebrow approach, with endoscopic assistance, leads to a higher extent of resection and lower rate of complications than the purely endonasal endoscopic approach. The endonasal endoscopic approach by itself may be suitable for a small percentage of cases. The combined above-and-below approaches are useful for large tumors with invasion of the ethmoid sinuses.

Expandable Polyaryl-Ether-Ether-Ketone Spacers for Interbody Distraction in the Lumbar Spine.

Study Design Retrospective case series. Objective StaXx XD (Spine Wave, Inc., Shelton, CT, United States) is an expandable polyaryl-ether-ether-ketone (PEEK) wafer implant utilized in the treatment of lumbar degenerative disease. PEEK implants have been successfully used as interbody devices. Few studies have focused on expandable PEEK devices. The aim of the current study is to determine the radiographic and clinical outcome of expandable PEEK cages utilized for transforaminal lumbar interbody fusion in patients with lumbar degenerative diseases. Methods Forty-nine patients who underwent lumbar interbody fusion with implantation of expandable PEEK cages and posterior instrumentation were included. The clinical outcome was evaluated using the visual analog scale (VAS) and the Oswestry Disability Index (ODI). Radiographic parameters including disk height, foraminal height, listhesis, local disk angle of the index level/levels, regional lumbar lordosis, and graft subsidence were measured preoperatively, postoperatively, and at latest follow-up. Results At an average follow-up of 19.3 months, the minimum clinically important difference for the ODI and VAS back, buttock, and leg were achieved in 64, 52, 58, and 52% of the patients, respectively. There was statistically significant improvement in VAS back (6.42 versus 3.11, p < 0.001), VAS buttock (4.66 versus 1.97, p = 0.002), VAS leg (4.55 versus 1.96, p < 0.001), and ODI (21.7 versus 12.1, p < 0.001) scores. There was a significant increase in the average disk height (6.49 versus 8.18 mm, p = 0.037) and foraminal height (15.6 versus 18.53 mm, p = 0.0001), and a significant reduction in the listhesis (5.13 versus 3.15 mm, p = 0.005). The subsidence of 0.66 mm (7.4%) observed at the latest follow-up was not significant (p = 0.35). Conclusions Midterm results indicate that expandable PEEK spacers can effectively and durably restore disk and foraminal height and improve the outcome without significant subsidence.

Corresponding Ganglion Cell Atrophy in Patients With Postgeniculate Homonymous Visual Field Loss.

BACKGROUND: The goal of our study was to look for the presence of homonymous ganglion cell layer-inner plexiform layer complex (GCL-IPL) thinning using spectral-domain optical coherence tomography (SD-OCT) in patients with a history of adult-onset injury to the postgeniculate pathways with rigorous radiological exclusion of geniculate and pregeniculate pathology. METHODS: We performed a retrospective review of twenty-two patients (ages 24-75 y, 6 men, 16 women) with homonymous visual field (VF) defects secondary to postgeniculate injury examining the GCL-IPL with SD-OCT. An additional fifteen patients (ages 28-85 y, 5 men, 10 women) with no visual pathway pathology served as controls. Using segmentation analysis software applied to the macular scan, a normalized asymmetry score was calculated for each eye comparing GCL-IPL thickness ipsilateral vs contralateral to the patient's brain lesions. RESULTS: We found that 15 of the twenty-two subjects had a relative thinning of the GCL-IPL ipsilateral to the postgeniculate lesion in both eyes (represented by a positive normalized asymmetry score in both eyes), whereas a similar pattern of right/left asymmetry was found in 4 controls (P = 0.0498). The magnitude of asymmetry was much greater in subjects compared with controls (P = 0.0004). There was no association between the degree of GCL-IPL thinning and the mean deviation on automated VF testing. A moderate correlation (R = 0.782, P = 0.004) between the magnitude of thinning and latency from onset of retrogeniculate injury was observed only after excluding patients beyond a cutoff point of 150 months. CONCLUSIONS: This data provides compelling new evidence of retrograde transsynaptic degeneration causing retinal ganglion cell loss after postgeniculate visual pathway injury.

Extreme lateral interbody fusion for unilateral symptomatic vertical foraminal stenosis.

PURPOSE: Asymmetric loss of disc height in adult deformity patients may lead to unilateral vertical foraminal stenosis and radiculopathy. The current study aimed to investigate whether restoration of foraminal height on the symptomatic side using extreme lateral interbody fusion (XLIF) would alleviate unilateral radiculopathy. METHODS: In a retrospective study, patients with single-level unilateral vertical foraminal stenosis and corresponding radicular pain undergoing XLIF were included. Functional data (visual analog scale (VAS) for buttock, leg and back, as well as Oswestry Disability Index (ODI)) and radiographic measurements (bilateral foraminal height, disc height, segmental coronal Cobb angle and regional lumbar lordosis) were collected preoperatively, postoperatively and at the last follow-up. RESULTS: Twenty-three patients were included, among whom 61 % had degenerative scoliosis. History of previous surgery at the level of index was present in 43 % of patients. Additional instrumentation was performed in 91 %. The foraminal height on the stenotic side was significantly increased postoperatively (p < 0.001), and remained significantly increased at the last follow-up of 11 ± 3.7 months (p < 0.001). Additionally, VAS buttock and leg on the stenotic side, VAS back and ODI were significantly improved postoperatively and at the last follow-up (p ≤ 0.001 for all parameters). The foraminal height on the stenotic side showed correlation with the VAS leg on the stenotic side, both postoperatively and the last follow-up (r = -0.590; p = 0.013, and r = -0.537; p = 0.022, respectively). CONCLUSIONS: Single-level XLIF is an effective procedure for treatment of symptomatic unilateral foraminal stenosis leading to radiculopathy. In deformity patients with radicular pain caused by nerve compression at a single level, when not associated with other symptoms attributable to general scoliosis, treatment with single-level XLIF can result in short- and mid-term satisfactory outcome.

Isolated cortical vein thrombosis: case series.

OBJECT: Isolated cortical vein thrombosis (ICVT) accounts for less than 1% of all cerebral infarctions. ICVT may cause irreversible parenchymal damage, rendering early and accurate diagnosis critical. This case series and literature review presents the clinical and radiological findings in 7 patients with ICVT, and highlights risk factors and imaging modalities that may be most beneficial in rendering an accurate and timely diagnosis. METHODS: Patients with CT and MRI findings consistent with ICVT examined between January 2011 and June 2014 were included in this retrospective review. RESULTS: Seven patients (5 females, 2 males), ranging in age from 11 months to 34 years, met the inclusion criteria. The most common clinical presentations were headaches (n = 4) and seizures (n = 3). The most common comorbidities noted in these patients were hypercoagulable states (n = 4) and intracranial hypotension (n = 3). Five patients had intraparenchymal involvement. CT suggested the correct diagnosis in 4 patients, and MRI confirmed the diagnosis in all 7 patients. All patients who received anticoagulation therapy (n = 5) experienced complete resolution of their symptoms. CONCLUSIONS: The majority of these patients were adult females, consistent with published data. Seizures and headaches were the most common presenting symptoms. Hypercoagulable state and intracranial hypotension, both known risk factors for thrombosis, were the most commonly noted ICVT risk factors. Intraparenchymal involvement was prevalent in nearly all ICVT cases and presented as vasogenic edema, early intraparenchymal hemorrhage, or hemorrhagic venous infarction. Susceptibility-weighted imaging was the most sensitive imaging technique in diagnosing ICVT.

A Percutaneous Transtubular Middle Fossa Approach for Intracanalicular Tumors.

OBJECTIVE: In cases of small intracanalicular tumors (≤ 1.5 cm), the middle fossa approach (MFA) provides the ability for adequate tumor removal with preservation of existing auditory function. Application of a minimally invasive tubular retractor in this approach may help mitigate the risk of postoperative seizures, aphasia, and venous complications by minimizing intraoperative retraction of the temporal lobe. We propose a minimally invasive microscopic and/or endoscopic percutaneous transtubular MFA for the management of intracanalicular tumors. METHODS: Subtemporal keyhole craniectomies were performed on 5 preserved cadaveric heads (10 sides), with 6 sides previously injected with a synthetic tumor model. A ViewSite Brain Access System tubular retractor (Vycor Medical, Inc., Boca Raton, Florida, USA) was used to provide minimal temporal retraction and protection of the surrounding anatomy. An extradural dissection of the internal auditory canal was performed under microscopic and endoscopic visualization with a minimally invasive surgical drill and tube shaft instruments, the intracanalicular tumors were removed, and degree of resection was assessed. RESULTS: All 10 approaches were completed successfully through the tubular retractor with minimal retraction of the temporal lobe. Excellent visualization of the structures within the internal auditory canal was achieved with both the microscope and 3-dimensional endoscope. On the 6 synthetic intracanalicular tumors resected, 5 gross total (Grade I) and 1 near total (Grade II) resections were achieved. CONCLUSION: A percutaneous transtubular MFA is a feasible minimally invasive option for resection of small intracanalicular tumors with potential preservation of auditory function, reduced temporal retraction, and enhanced protection of surrounding structures.

Three-dimensional volumetric assessment of the nasolacrimal duct in patients with obstruction.

PURPOSE: The purpose of this study was to determine if a significant difference exists in the nasolacrimal duct volume of subjects with primary nasolacrimal duct obstruction compared with that of controls. METHODS: This was a retrospective, case-control study of 70 subjects with prior maxillofacial CT scans, including 35 subjects with obstruction and 35 controls. Volume measurements of the nasolacrimal duct were made on a GE Advantage Workstation using volume viewer software, and measurements were compared using an unpaired Student t test. Interrater and intrarater reliabilities were calculated. RESULTS: There was no significant difference in the nasolacrimal duct volume of patients (0.411 ± 0.18 cm) compared with that of controls (0.380 ± 0.13 cm(3)) (p = 0.23). Women had smaller volume ducts (0.356 ± 0.11 cm(3)) than that of men (0.482 ± 0.19 cm(3)) (p < 0.001). Male patients had smaller volume ducts (0.470 ± 0.23 cm(3)) than that of male controls (0.493 ± 0.14 cm(3)) (p = 0.70), while female patients (0.384 ± 0.13 cm(3)) had significantly larger volume ducts than that of female controls (0.328 ± 0.08 cm(3)) (p = 0.01). There was excellent interrater and intrarater reliabilities. CONCLUSIONS: CT 3-dimensional volumetric software can be used to accurately measure the nasolacrimal duct volume in patients with obstruction. Both the absence of a significant difference in patient's and control's nasolacrimal duct volumes and the overlap in range between the 2 groups imply that the volume of the tear duct is likely not related to the etiology of obstruction. The increase in volume seen in females with obstruction may be due to expansion of the bony canal during the postmenopausal years. The exact etiology of primary nasolacrimal duct obstruction requires further investigation.