Optic Nerve Canal Research Articles

Extent of optico-carotid recess is significantly associated with presence of bony dehiscences and bone thickness in the optico-carotid area

Background: The objectives of this study were to evaluate the frequency of bony dehiscences in the optico-carotid recess (OCR) area and to measure the thickness of the bony lamellas bordering the OCR, according to our previously proposed OCR classification taking into account the extent of the recess. Methodology: A total of 100 human cadaver heads (n= 200 sphenoid sinuses) were investigated. Samples were divided into groups according to the presence and extent of OCR (no OCR, sub-optical OCR, latero-optical OCR). Bony dehiscences were visually identified and bone thickness was measured by using a high-resolution micrometer. Results: A bony dehiscence in the OCR area was observed in 20%. A significant difference in bony dehiscence occurrence rate between OCR types was found. The wall thickness of the bony carotid artery- and optic nerve canals bordering the OCR were 0.25 ± 0.16 mm and 0.27 ± 0.15 mm, respectively. Significant differences between OCR groups in bony wall thickness of the carotid artery canal and optic nerve canal were found. Samples with a latero-optical OCR had a significant thinner wall of the carotid artery and optic nerve canal than samples with a sub-optical OCR and no OCR. Conclusions: The current results indicate that the presence of an extended OCR, e.g. latero-optical, is highly associated with a greater risk of bony dehiscences and thinner bony lamellas in the OCR region.

Orbital Extramedullary Plasmacytoma: Case report and literature review

Extramedullary plasmacytoma is a rare disease, characterized histopathologically by infiltration of plasma cells of different maturities and producing monoclonal immunoglobulin outside the bone marrow. J.R.G., 52 years old, male, sought medical assistance due to amaurosis and blocked eye movements. We performed Magnetic Nuclear Resonance of the skull that showed discrete intermediate signal tissue, next to the optic nerve canal and homolateral superior orbital fissure, with slight extension to the lower orbital fissure, associated with thickening of the corresponding meninges, involving the proximal portion of the optic nerve, measuring 1.3 x 1.1 x 2.5 cm. Non-specific aspect, but suggestive of lymphoproliferative lesion. Right and extraorbital tumor excision was performed, in which it was not possible to completely resect the tumor. The anatomopathological examination of the piece showed a neoplasm of plasma cells (plasmacytoma). The diagnosis is made from the exclusion of Multiple Myeloma. The treatments of choice are radiotherapy, due to the high radiosensitivity in 80–100% of cases, and surgery for localized lesions.

Optic nerve head anatomy in myopia and glaucoma, including parapapillary zones alpha, beta, gamma and delta: Histology and clinical features.

The optic nerve head can morphologically be differentiated into the optic disc with the lamina cribrosa as its basis, and the parapapillary region with zones alpha (irregular pigmentation due to irregularities of the retinal pigment epithelium (RPE) and peripheral location), beta zone (complete RPE loss while Bruch's membrane (BM) is present), gamma zone (absence of BM), and delta zone (elongated and thinned peripapillary scleral flange) within gamma zone and located at the peripapillary ring. Alpha zone is present in almost all eyes. Beta zone is associated with glaucoma and may develop due to a IOP rise-dependent parapapillary up-piling of RPE. Gamma zone may develop due to a shift of the non-enlarged BM opening (BMO) in moderate myopia, while in highly myopic eyes, the BMO enlarges and a circular gamma zone and delta zone develop. The ophthalmoscopic shape and size of the optic disc is markedly influenced by a myopic shift of BMO, usually into the temporal direction, leading to a BM overhanging into the intrapapillary compartment at the nasal disc border, a secondary lack of BM in the temporal parapapillary region (leading to gamma zone in non-highly myopic eyes), and an ocular optic nerve canal running obliquely from centrally posteriorly to nasally anteriorly. In highly myopic eyes (cut-off for high myopia at approximately -8 diopters or an axial length of 26.5mm), the optic disc area enlarges, the lamina cribrosa thus enlarges in area and decreases in thickness, and the BMO increases, leading to a circular gamma zone and delta zone in highly myopic eyes.

Transorbital Endoscopic Medial Orbitotomy and Decompression of the Optic Nerve in Patients with Endocrine Ophthalmopathy Complicated by Optical Neuropathy

AIM OF STUDY: to improve the results of surgical treatment of patients with endocrine ophthalmopathy complicated by optical neuropathy. For this, medial orbitotomy and decompression of the optic nerve were performed for a patient with endocrine ophthalmopathy, CAS<3, OD=18 mm, OS=23 mm and visual acuity OD=1.0 OS=0.2, using transorbital transconjunctival endoscopic access. The first step was a retro caruncular incision. After that, we defined an access to the medial wall of the orbit with its subsequent resection. Then, we performed ethmoidectomy and approach to the optic nerve canal. Upon completion of bone decompression, we opened periorbitis.RESULTS. The postoperative period was uneventful. In the early postoperative period, regression of exophthalmos was observed OD=18 mm, OS=20 mm, improvement in visual acuity OD=1.0 OS=0.5 . No complications were recorded. A satisfactory result was obtained.CONCLUSION. Transorbital endoscopic medial orbitotomy and optic decompression can be effectively used in the treatment of patients with endocrine ophthalmopathy complicated by optic neuropathy, refractory to conservative therapy. The technique is promising and requires further randomized studies.

Sphenoid Sinus and Related Neurovascular Structures-Anatomical Relations and Variations on Radiology-A Retrospective Study.

The aim of this study was to evaluate sphenoid sinus pneumatisation and its anatomical relation with adjacent neurovascular structures in Indian population. We performed a retrospective cross-sectional study, in which the pattern of sphenoid sinus pneumatization was studied on high-resolution computed tomography scans (n = 400), and association of the optic nerve, vidian canal and foramen rotundum along with related morphometric measurements were studied. Out of 400 CT scans, 60.5% were males. Majority had sellar type of pneumatization (89.5%) and single intersinus septum (68%). The most common configuration of relation of optic nerve canal was DeLano type 2 (34.75%). Vidian canal (VC) and Foramen rotundum (FR) were found dehiscent in 40.5% and 6.38% respectively. Average distance of FR from midline on right and left side was 16.3 ± 2.19mm and 16.7 ± 2.23mm respectively. Average distance of VC from midline on right and left side was 12.4 ± 5.84mm and 12.4 ± 4.18mm respectively. Average right FR to VC distance was 4.17 ± 2.16mm and left FR to VC was 4.44 ± 2.20mm. Anatomical variations of the sphenoid sinus are well known. In the present study, we have tried to highlight the importance of knowledge of various anatomical variations in relations to sphenoid sinus as they are critical in planning of surgery. Pre-operative radiological study and correlation is inevitable to assess type and extent of sinus pneumatisation, bony dehiscence and septal terminations to avoid injury to vital structures.

Transcranial microsurgical decompression of the optic canal in surgical treatment of meningiomas of the sellar region

Transcranial microsurgical decompression of the optic canal in surgical treatment of meningiomas of the sellar region

Sagittal bending of the optic nerve at the entrance from the intracranial to the optic canal and ipsilateral visual acuity in patients with sellar and suprasellar lesions.

Visual acuity impairment due to sellar and suprasellar tumors is not fully understood. The relationship between these tumors and disturbance of visual function was examined using preoperative MRI. This study reviewed 93 consecutive patients with sellar and suprasellar tumors. Best-corrected visual acuity (BCVA) and visual impairment score (VIS) were used for estimation of visual impairments. Preoperative MR images were examined to obtain several values for estimation of chiasmatic compression. Additionally, the optic nerve-canal bending angle (ONCBA) was newly defined as the external angle formed by the optic nerve in the optic canal and the optic nerve in the intracranial subarachnoid space at the junction, using preoperative sagittal T2-weighted MR images. The mean ONCBA was about the same on the right (44° ± 25°) and the left (44° ± 24°). Sagittal ONCBA was defined as large (> 45°) and moderate (≤ 45°) on each side. Preoperative VIS was found to be significantly worse if the right or left ONCBA (or both) was large (right side: ONCBA large [median 20, IQR 8-30] > ONCBA moderate [median 10, IQR 3-17], p = 0.003, Mann-Whitney U-test; left side: ONCBA large [median 22, IQR 9-30] > ONCBA moderate [median 10, IQR 2-16], p = 0.001). A large ONCBA showed a significant relationship with unfavorable ipsilateral BCVA (> logMAR, 0; right side, p = 0.001, left side, p = 0.001, chi-square test). The ONCBA had a positive correlation with ipsilateral BCVA (right: r = 0.297, p = 0.031; left: r = 0.451, p = 0.000, Pearson's correlation coefficient). Preoperative BCVA was significantly lower on the same side in the large ONCBA group compared with the moderate ONCBA group (right side: large ONCBA 0.169 ± 0.333 [logMAR, mean ± standard deviation] vs moderate ONCBA 0.045 ± 0.359, p = 0.026, Student t-test; left side: large ONCBA 0.245 ± 0.346 vs moderate ONCBA 0.025 ± 0.333, p = 0.000). This visual acuity impairment improved after resection of the tumors. Sagittal bending of the optic nerve at the entrance from the intracranial subarachnoid space to the optic canal may be related to ipsilateral deterioration of visual acuity in sellar and suprasellar lesions. Sagittal T2-weighted MRI is recommended for preoperative estimation of the optic nerve bending.

Endoscopic Optic Nerve Decompression: Indications, Technique, Results

For decades, treatment of compressive optic nerve neuropathy was conservative and involved the intravenous application of high-dose corticoids, which was combined with nerve growth factors in later years. If surgery was considered, transcranial and transfacial access to the orbital apex and the optic nerve were achieved using classical approaches. Over the past decade, endonasal endoscopic procedures have increasingly come into force, based on favorable experiences with functional endoscopic sinus surgery and as a result of innovative developments in endoscopy and image guidance. The purpose of this review is to address the latest literature in this field with regard to the indications, techniques, results, and complications associated with this procedure. There are basically two approaches for endoscopic optic nerve decompression: the extradural supraorbital “keyhole” approach, which provides access to the optic nerve canal roof and which is usually performed by neurosurgeons, and the endonasal endoscopic approach, which is widely used by otorhinolaryngologists. The development and application of endonasal endoscopic surgery was only possible with extensive knowledge of the topographic anatomy. The most important anatomical landmarks and topography have been described based on either cadaveric or CT scan studies, and include the opticocarotid recess, the distance between the optic nerve canal and the internal carotid artery, the ophthalmic artery, and the length of the optic nerve canal. There are two main indications for endonasal endoscopic optic nerve decompression: (1) traumatic optic nerve neuropathy (TON), and (2) optic nerve neuropathy from non-traumatic causes (nTON), such as tumorous conditions, inflammatory diseases, or idiopathic intracranial hypertension (IIH). In trauma cases, rates of postoperative visual improvement of 40–80% have been reported. Factors influencing the outcome include the severity of the injury, initial visual acuity (light perception or better vs. no light perception), the time interval between trauma and intervention, and the type of injury, such as fracture lines directly through the optic nerve canal or probable avulsion trauma. nTON cases generally have a slightly better prognosis, with vision improvement of 54–100% reported. The procedure should be performed before any optic nerve atrophy can occur. In IIH cases, all major symptoms, including vision loss, headache, visual field deterioration, and papilla edema, improved after optic nerve decompression, with rates of 60–100% reported. Earlier studies reported the occurrence of major complications such as cerebral fluid leakage, severe hemorrhage, or optic nerve injury at rates of about 3%. However, more recent studies postulate that no major complications occur, which may reflect the increasing use of the endonasal endoscopic route to the optic nerve and skull base as standard procedure, so that surgeons are becoming more comfortable with the technique. Endonasal endoscopic optic nerve decompression is a safe and highly effective treatment to reduce hydrostatic pressure on the optic nerve in cases of optic nerve neuropathy of various etiologies. In TON cases, about 50% of patients will benefit from the procedure, with vision improvement possible in some cases even with an interval of some days between trauma and surgery. Non-trauma cases have a slightly better prognosis. The intervention should be performed prior to optic nerve atrophy.

The Analysis of Computed Tomography of Paranasal Sinuses in Nasal Septal Deviation.

Anatomic variations of paranasal sinuses are frequent among population that should be analyzed and interpreted accurately. The purpose of this study is to analyze anatomical variants and their relationships of paranasal sinuses in patients with nasal septal deviation undergoing septoplasty. A total number of 150 patients (74 males, 76 females) with nasal septal deviation undergoing septal surgery were included in this retrospective study. The authors analyzed the direction and the angle of the nasal septal deviation, variations of the nasal turbinates, ethmoidal air cells, paranasal sinus pneumatization, accessory pneumatization of the paranasal complex and sphenoid sinus-related structures and the Keros, optic nerve and Vidian canal classification, and relationships between these structures in the paranasal computed tomography of the patients. The incidence of concha bullosa, Onodi cell, and anterior clinoid pneumatization were higher in patients with nasal septal deviation when compared with current literature. Physicians and surgeons dealing with the nose and maxillofacial region should be able to analyze paranasal computed tomography by themselves and must be aware of these variations during performing septal and craniomaxillofacial surgery.

Is there a relationship between Onodi cell and optic canal?

We investigated the relationship between Onodi cells and optic canal by paranasal sinus computed tomography (PNSCT). In this retrospective study, 508 PNSCT (265 males and 243 females) was examined. Onodi cell presence, pneumatization types, optic canal types; and also sphenoid sinusitis and anterior clinoid process pneumatization were evaluated. The prevalence of Onodi cells was 21.2% of the patients. Onodi cells were observed 40.7% on the right side and 25.9% on the left side. In 33.4% of the patients, bilateral Onodi cells were present. Male/Female ratio was 24.5%/17.6%. Onodi cell types were detected as Type I > Type II > Type III bilaterally. There was a positive correlation between the right and left Onodi cell types (p < 0.05). Optic canal types were detected as Type IV > Type I > Type II > Type III. bilaterally. There was a positive correlation between right and left optic canal types. Onodi cell presence and ACP pneumatization were found as statistically significant (p < 0.05). In 65.5% of the patients, Onodi cells and ACP pneumatization were absent. ACP pneumatization was present in 35.4% of the cases. In nine cases, bilateral Onodi cells and ACP pneumatization were detected. Sphenoid sinusitis was detected in 11.4% of Type I and 13.8% of the Type II Onodi cells on the right side. On the left side, it was detected in 12.9% of the Type I and 19.0% of Type II Onodi cells. Identification of Onodi cell is very important clinically because of its proximity to optic nerve canal. We concluded that type IV Onodi-optic canal relationship was the most common finding in our study. Onodi cell presence and their patterns of pneumatization must be evaluated on PNSCT preoperatively to avoid optic canal damage.

The effect of frontal sinus pneumatization on anatomic variants of paranasal sinuses.

The aim of this study is to determine the effect of frontal sinus pneumatization on various variations of paranasal sinuses on maxillofacial CT. A total number of 120 patients (62 females, 58 males) were included in this study. Patients were divided into three groups regarding their frontal sinus pneumatization extent on paranasal sinus CT as Type 1 pneumatization (aplasia and hypoplasia), Type 2 pneumatization (medium) and Type 3 pneumatization (hyperplasia). The prevalence of various variations on paranasal sinus CT like pneumatization of upper and middle concha, presence of agger nasi, Haller and Onodi cell, maxillary sinus and sphenoid sinus hypoplasia, pneumatization of anterior clinoid process, pterygoid process and greater wing of sphenoid sinus, dehiscence and protrusion of internal carotid artery and optic nerve and vidian canal types were ascertained and compared within each group. The prevalence of upper and middle concha pneumatization, Haller cell, pneumatization of anterior clinoid process, pterygoid process and greater wing of sphenoid and internal carotid artery dehiscence and protrusion was higher in Type 3 group compared with other groups. Excessive pneumatization of frontal sinus has various effects on paranasal sinus variations at maxillofacial CT. Surgeons dealing with endoscopic sinus surgery, maxillofacial and skull base surgery must be vigilant of association between certain variations when analyzing CT scan preoperatively for avoiding complications.

Evaluation of Anatomical Variations on Paranasal Sinus CT

OBJECTIVES: The purpose of this study is to analyze and assess the frequency of anatomical variants of paranasal sinuses scanned by multidetector computed tomography (MDCT). METHODS: A total number of 225 patients (122 males, 103 females) with a median age of 28 (15-77) years were included in this retrospective study. We analyzed the presence of the nasal septal deviation (NSD), variations of the nasal turbinates, ethmoidal air cells, paranasal sinus pneumatization, accessory pneumatization of the paranasal complex, variations of the sphenoid sinus related structures and the optic nerve and vidian canal classification in the paranasal computed tomography (CT) of the selected patients. RESULTS: NSD was present in 124 (55.1%) patients, superior concha pneumatization in 30 (13.3%), middle concha pneumatization in 100 (44.4%), agger nasi cells (ANC) in 192 (85.3%), Haller cells in 47 (20.9%), Onodi cells in 44 (19.6%), maxillary sinus hypoplasia in 6 (2.6%), frontal sinus hypoplasia in 29 (12.9%), frontal sinus aplasia in 7 (3.1%), sphenoid sinus hypoplasia in 7 (3.1%), uncinate process pneumatization in 12 (5.3%), anterior clinoid process (ACP) pneumatization in 60 (26.7%) and pterygoid process (PP) pneumatization in 75 (33.3%) patients. Optic nerve Type 1 was detected in 122 (54.2%) patients, Type 2 in 29 (12.9%), Type 3 in 36 (16%) and Type 4 in 38 (16.9%) patients. Vidian canal Type 1 was observed in 37 (16.4%), Type 2 in 95 (42.2%) and Type 3 in 93 (41.3%) patients. CONCLUSION: The analysis of the paranasal CT is crucial in diagnosis of miscellaneous diseases of the paranasal sinuses. The anatomical variations of the sinuses are prevalent among the population, so otolaryngologists should be aware of these variations for precise diagnosis and to avoid surgical complications.

Transcranial subdural decompression of the optic canal as a treatment option for traumatic optic neuropathy

Objective To investigate the effect of decompression of the optic nerve canal by subdural approach on traumatic optic neuropathy (TON) and the predictive value of DTI. Methods A total of 52 cases with optic nerve neuropathy which underwent microsurgical depression via transcranial subdural approach were retrospectively analyzed from January 2008 to December 2017 at the Neurosurgical Department of No. 101 Hospital of PLA. Before operation, CT and DTI scans were administered. Results The patients were followed up for 3 months after operation. Forty-three patients required the sight recovery to some extent after operations. The effective rate was 82.7% (43/52) and the significant effective rate was 26.9% (14/52). The 43 patients who totally lost their sights had the effective rate of 88.2% (34/43) and the significant effective rate of 27.9% (12/43). Five patients underwent DTI examination. 2 patients whose the optic nerve conduction bundles were not complete the sights did not recover after operation. Another 3 patients whose DIT examination showed the optic nerve conduction beam was intact the postoperative sights were effectively restored. Conclusions The decompression of the optic nerve canal by subdural approach seems safe and effective for the patients of TON. The length of duration longer than 72 hours post injury in the TON patients could not exclude the chance of operation. DTI might be the important predictor for the effect of the operation. Key words: Optic nerve injuries; Subdural space subdural; Neurosurgical procedures; Decompression of optic nerve; Treatment outcome

Transsphenoidal surgery of suprasellar meningiomas - is there a future for the technique?

The study objective was to evaluate the role of extended transsphenoidal endoscopic endonasal approaches in surgery of suprasellar meningiomas. The present study is a retrospective analysis of surgical treatment outcomes in 45 patients (11 males and 34 females aged 23 to 70 years (median, 50 years) with suprasellar meningiomas who underwent surgery for skull base tumors using the anterior extended transsphenoidal endoscopic endonasal approach in the Surgery Department of the Burdenko Neurosurgical Institute in the period from 2009 to 2017. In all cases, surgery was the primary method of treatment. Total tumor resection (the tumor was resected completely together with an infiltrated DM - Simpson 1) was achieved in 77.8% (35/45) of cases; subtotal resection (more than 80% of the tumor was removed) was in 17.8% (8/45) of cases; in 4.4% (2/45) of cases, resection was partial (less than 80% of the tumor was resected). Worsening or development of visual impairments immediately after surgery occurred in 13 (28%) of 45 patients. In 3 of them, vision was completely recovered on conservative treatment by the time of hospital discharge. In 4 patients, vision partially improved by the time of discharge. In 6 patients, vision was not recovered by discharge (in 2 of them, vision partially improved during follow-up). Therefore, by the time of hospital discharge, deterioration in vision occurred in 10 (22%) of 45 patients. In 7 (21.2%) out of 33 patients who had visual impairments before surgery, there was an improvement in vision in the postoperative period. Analyzing the findings and generalizing our experience, we may say that, in surgery of suprasellar meningiomas, the anterior extended transsphenoidal endoscopic endonasal approach should be used for relatively small (up to 3 cm), medially located symmetrical tumors that do not involve large vessels. The efficacy of this technique for tumors extending into the optic nerve canals requires additional analysis in a larger series of cases.

The prevalence of the Onodi cell – Most suitable method of CT evaluation in its detection

BackgroundThe Onodi cell (sphenoethmoidal air cell) is an anatomic variant of the most posterior ethmoid cell that pneumatised superiorly and laterally to the sphenoid sinus, and is in close relation to the optic nerve. The proper identification of the Onodi cell is essential during a pre-operative computer tomography (CT) examination, as the presence of that ethmoid cell variant makes sphenoid sinus surgery more risky. The bulging of the optic nerve to the ethmoid cell wall is well visualized during endoscopic examination, but there are no clearly defined criteria for a potentially dangerous Onodi cell type in CT examinations. ObjectiveTo determine the prevalence and types of Onodi cell in CT examination and find the most suitable CT scanning planes to identify it. Material and methodsThree plane (axial, coronal and sagittal) reconstructions of 196 paranasal sinuses were analyzed. The most posterior ethmoid cell was classified into four types, according to its position in relation to the sphenoid sinus and the optic nerve canal bulging into the lumen of the sphenoethmoid cell. ResultsThe Onodi cell was detected in 39.8% of cases, although in 55.6% of cases a direct contact between the most posterior ethmoid cell and the optic nerve was present. Bulging of the optic nerve canal was seen in 25% of cases. In two cases two posterior ethmoid cells were in direct contact with the optic nerve canal. ConclusionThe prevalence of the Onodi cell was higher than previously reported. Pre-operative paranasal sinuses CT examination should be evaluated in all three planes (axial, coronal and sagittal) to avoid missing or over-detection of the Onodi cell. Axial and sagittal planes are preferable for the detection of the Onodi cell.

Three-dimensional Optical Coherence Tomography Imaging and Treatment of Glaucomatous Optic Nerve Head Defects Associated with Schisis-like Maculopathy

We present the three-dimensional (3D) spectral-domain optical coherence tomography (SD-OCT) findings of schisis-like maculopathy associated with structural changes of the optic nerve (ON) head as well as the treatment outcomes of a case of advanced glaucoma. In addition to ophthalmological examination, B-scan and 3D-SD-OCT images of the ON head, peripapillary retina, and the macula were obtained. The B-scan images only detected typical retinoschisis findings. However, the 3D-SD-OCT images of the ON head revealed defects of various sizes, shapes, and depths at the outer wall of the prelaminar and laminar regions of the ON canal. The 3D images were able to establish that these defects were both adjacent to and interconnected with the retinal layers. The patient successfully received 3D-SD-OCT-guided thermal laser treatment that is used in congenital optic disc pits complicated with macular schisis. In brief, 3D-SD-OCT is very useful for demonstrating the ON head defects that can lead to schisis-like maculopathy in cases of advanced glaucoma.

Optic Nerve Canal Relation to Posterior Paranasal Sinuses in Indian Ethnics: Review and Objective Classification.

Posterior paranasal sinuses consisting of posterior ethmoid and sphenoid sinuses show varying pneumatization and relationship to Optic Nerve Canal (ONC). Most commonly ONC is superolateral to sphenoid sinus, however varied protrusion of ONC into the sinuses may occur. Rarely it may pass completely through the sinus. Optic Nerve (ON) is covered by a thin bony layer or by periosteum and sinus mucosa without bone. Extensive pneumatization of sphenoid sinus and bony dehiscence predisposes to ON injury. The posterior ethmoid cell namely the Onodi cell is of great surgical importance when the ON is along its lateral wall and surrounds the nerve. These varied relations imply that a detailed knowledge of the intimate relationship of ONC with the posterior paranasal sinuses is necessary to avoid unintentional complications during the surgeries involving the ONC region. To assess relationship of ONC to the posterior paranasal sinuses in Indian Ethnic study group. Retrospective review of 100 paranasal sinus Computed Tomography (CT) scans were done using 64 row Multi Detector Computed Tomography (MDCT). Multiplanar reformation images were assessed for ONC relation to posterior ethmoid and sphenoid sinuses, wall dehiscence, and Pneumatization of Anterior Clinoid Process (PACP). 200 optic nerve canals were assessed and grouped into four types based on the modification of Delano et al., classification. The most common OCN was Type-1 (60%), followed by Type-2 (15%), Type-3 (14%) and Type-4 (11%). Dehiscence was seen in 35(17.5%) mostly in Type-3 canals. PACP was seen in 30 (15%). Knowledge of ON relationship to posterior paranasal sinuses will reduce the devastating complications during sinus surgeries. Our modified ONC classification is based on the bony canal morphology and the degree of protrusion into sinuses. As with other reported studies worldwide, Type-1 ONC is the commonest among the Indians also. Type-2 and 3 ONC with sinus wall dehiscence and PACP are the most important anatomical variations which may potentially predispose to risk of surgical injury to the optic nerves.

Pneumatization patterns of onodi cell on multidetector computed tomography

Background: Onodi cell is the most common anatomical variant of posterior ethmoidal air cells. Pneumatization patterns of Onodi cell are important clinically due to its proximity to optic nerve and internal carotid artery canal. Multidetector computed tomography (MDCT) provides the best imaging modality for identification and pneumatization pattern of Onodi cell. Objectives: The present study is done to know the patterns of pneumatization of Onodi cell by 128 slice MDCT. Materials and Methods: This was a retrospective analysis of paranasal sinuses in 1080 cases by MDCT in adults. Axial images of paranasal sinuses were taken by 128 MDCT with further multiplanar reconstruction to identify Onodi cell and their pneumatization patterns. Statistical analysis was done using SPSS version 20, and 95% confidence interval (CI) values were calculated using a confidence Interval calculator for proportional values. Results: A total of 260 cases (24.07%, CI - 21.52%–26.62%) showed Onodi cell among the total 1080 cases included in this study. Males formed more cases than females with 62.69% and 37.31%, respectively, Type II was the most common pattern of pneumatization with 56.55% (CI - 50.12–62.18), followed by Type I with 41.53% (CI - 35.54–47.52) and Type III with 1.92% (CI - 0.25–3.59) of cases. Conclusion: Onodi cell is the most common anatomical variation of ethmoidal sinuses with higher prevalence among Asian populations. Their patterns of pneumatization are important clinically to avoid surgical damage to optic nerve and internal carotid artery canals. Onodi cell is better detected with MDCT and helpful for sinonasal surgeons for a better surgical outcome.

Analysis of relevant factors affecting the visual prognosis of traumatic optic neuropathy

To investigate the relevant factors affecting the prognosis of traumatic optic neuropathy (TON). A total of 685 cases (719 eyes) of TON from June 2007 to June 2012 were analyzed retrospectively. A total of 9 independent variables (X) including sex, side of TON, duration of coma, vision after trauma, fracture of optic nerve canal, fracture of big ridge of sphenoid bone, hematoma in sphenoid sinus and surgical treatment, and the dependent variable (Y) of visual prognosis were analyzed using the unconditioned Logistic regression analysis to find the risk factors for the visual prognosis of TON. A total of 325 eyes (45.2%) recovered out of 719 eyes. Four variables showed a significant relation with the visual recovery: duration of coma>0.5 h (X3, P<0.01), remnant vision after trauma (X4, P<0.01) and sphenoid ridge fractures (X7, P<0.01), and surgical treatment (X9, P<0.01). These factors above were also proved to be significant in Logistic regression. The duration of coma>0.5 h, no light perception after trauma, sphenoid ridge fractures are risk factors of visual recovery, while surgical treatment is the protective factor for the visual recovery after TON.

Interactive 3D-PDF Presentations for the Simulation and Quantification of Extended Endoscopic Endonasal Surgical Approaches.

A three-dimensional (3D) model of the skull base was reconstructed from the pre- and post-dissection head CT images and embedded in a Portable Document Format (PDF) file, which can be opened by freely available software and used offline. The CT images were segmented using a specific 3D software platform for biomedical data, and the resulting 3D geometrical models of anatomical structures were used for dual purpose: to simulate the extended endoscopic endonasal transsphenoidal approaches and to perform the quantitative analysis of the procedures. The analysis consisted of bone removal quantification and the calculation of quantitative parameters (surgical freedom and exposure area) of each procedure. The results are presented in three PDF documents containing JavaScript-based functions. The 3D-PDF files include reconstructions of the nasal structures (nasal septum, vomer, middle turbinates), the bony structures of the anterior skull base and maxillofacial region and partial reconstructions of the optic nerve, the hypoglossal and vidian canals and the internal carotid arteries. Alongside the anatomical model, axial, sagittal and coronal CT images are shown. Interactive 3D presentations were created to explain the surgery and the associated quantification methods step-by-step. The resulting 3D-PDF files allow the user to interact with the model through easily available software, free of charge and in an intuitive manner. The files are available for offline use on a personal computer and no previous specialized knowledge in informatics is required. The documents can be downloaded at http://hdl.handle.net/2445/55224 .