Transfrontoethmoidal Approach to Medial Intraconal Lesions: Laboratory Investigation

Object. The standard superior craniotomy approach through the orbital roof is obstructed by numerous muscles, nerves, and vessels. Accessing the medial intraconal space also involves considerable brain retraction. The authors present a modified approach through the frontal sinus that overcomes these limitations. Methods. Seven fixed silicone-injected cadaveric specimens were dissected bilaterally. In addition to the superior orbital wall, the ethmoidal sinuses and medial orbital wall were removed. The anatomical relationships between the major neurovascular complexes in the medial intraconal space and the optic nerve were observed. Results. Intraconally, working space was created both in a \ superior window\ between the superior oblique and levator palpebrae muscle and in a \ medial window\ between the superior oblique and medial rectus muscle. The superior window mainly created an ipsilateral trajectory to the deep target. The medial window, which created a contralateral trajectory, provided a more inferior view of the medial intraconal space. Removal of the medial orbital wall further widened the exposure obtained from the superior window. The combination of these working windows makes the medial surface of the optic nerve available for exploration from multiple angles. Most of the major neurovascular complexes of the posterior orbit can be retracted safely without impinging on the optic nerve. Conclusions. This novel extradural transfrontoethmoidal approach affords a direct view to the medial posterior orbit without major conflicts with intraconal neurovascular structures and requires minimal brain manipulation. The approach appears to offer advantages for medially located intraconal lesions

Microsurgical Anatomy and Quantitative Analysis of the Transtemporal- Transchoroidal Fissure Approach to the Ambient Cistern

OBJECTIVE: Surgical approaches to ambient cistern lesions are complex. We investigated the microanatomy of the transtemporal-transchoroidal fissure approach to the ambient cistern with emphasis on exposure of the posterior cerebral artery. METHODS: Dissections were performed bilaterally in five silicone-injected cadaveric heads. Critical anatomic distances, specifically with reference to the P2 segment of posterior cerebral artery in relation to the inferior choroidal point and P2-P3 junction, were measured with digital calipers. Other landmarks (temporal lobe tip, points from the temporal base to the choroidal fissure) were included for quantitative analysis. RESULTS: The transtemporal-transchoroidal fissure approach provided adequate exposure of the ambient cistern, minimized temporal lobe retraction, and allowed assessment of regional microanatomy. The mean distance from the temporal base to the choroidal fissure measured 18.09 mm (range, 16.9-21.9 mm). The distances from the choroidal fissure to P2 varied at the coronal plane of the inferior ehoroidal point (mean, 6.96 mm; range, 3.6-12.0 mm) and the P2-P3 junction (mean, 6.02 mm; range, 4.3-6.9 mm), respectively. CONCLUSION: The transtemporal-transchoroidal fissure approach provides a corridor to the ambient cistern and P2-P3 junction while minimizing temporal lobe retraction and avoiding interruption of temporal lobe venous drainage. Because of widely variable vascular anatomy, access to posterior cerebral artery lesions using this approach requires preoperative imaging to identify the specific location of the P2-P3 junction

Efficacy of 4-methyl-7-hydroxy coumarin derivatives against vectors <i style="">Aedes aegypti </i>and <i>Culex quinquefasciatus</i>

788-7924-Methyl-7-hydroxy coumarin is considered as a lead molecule as a biopesticide. Its mono bromo and tribromo derivatives were synthesized. Two more derivatives were synthesized by acylation. Compound 1 (3,6,8-tribromo-7-hydroxy-4-methyl-chromen-2-one) was found to be the most potent against IVth instar larvae of C. quinquefasciatus and A. aegypti the LC50 being 1.49 and 2.23 ppm respectively. It showed 100% larval mortality at 25 ppm against A. aegypti and at 10 ppm against C. quinquefasciatus. Compounds 1 and 2 (3,6,8-tribromo-7-hydroxy-4-methyl-chromen-2’-oxo-2H-chromen-7-yl acetate) showed remarkable ovicidal activity. Significant reduction of 80-85% hatching of eggs of both mosquito species was observed at the highest dose of 100 ppm. The hatched larvae showed 100% mortality in the successive instars. Compounds 3 and 4 (3-bromo-7-hydroxy-4-methyl-chromen-2-one and 3-bromo-4-methyl-2’-oxo-2H-chromen-7-yl acetate) showed moderate activity against both mosquito species

Assessment of various reciprocating system in the extrusion of debris from curved root canals: An original study

Introduction: The endodontic preparation depends largely on the file systems that are used in the canal preparations. The amount of the intracanal debris that is extruded from the apex may be influenced by the file systems. Hence, the present in vitro study evaluated the amount the debris that is extruded for the two file systems at different working lengths. Methods: Forty human mesiobuccal canals of the first molars were collected that were extracted for various causes. They were equally divided to four groups of Reciproc (full length), Reciproc (short by 1 mm), WaveOne Gold (full length), and WaveOne Gold (short by 1 mm). Routine crown-down technique was followed for the canal preparation with the intermittent irrigation. The extruded debris was weighed and compared for the significance. Results: The amount of the debris that was extruded weighed similarly in all the four groups with no significant variations. The Reciproc extruded lesser material than the WaveOne Gold. Conclusions: The file systems seem not to affect the debris extrusion irrespective of the files' physical properties. Further studies in a clinical setup are warranted

An anatomical evaluation of the mini-supraorbital approach and comparison with standard craniotomies

OBJECTIVE: To compare anatomically the surgical exposure provided by pterional (PT), orbitozygomatic (OZ), and minisupraorbital (SO) craniotomies. METHODS: Seven sides of six fixed cadaver heads injected with silicone were used. The mini-SO craniotomy followed by the PT and OZ approaches were performed sequentially. The bony flaps were attached with miniplates and screws, allowing easy conversion between the approaches. A frameless stereotactic device was used to calculate an area of surgical exposure and the angles of approach for six different anatomic targets. An image guidance system was used to demonstrate the limits of the surgical exposure for each technique. RESULTS: No significant differences were observed in the total area of surgical exposure when comparing the mini-SO (A = 1831.2 ± 415.3 mm), PT (A = 1860.0 ± 617.2 mm), and OZ approaches (A = 1843.3 ± 358.1 mm; P \u3e 0.05). Angular exposure was greater for the OZ and PT approaches than for the mini-SO approach, either in the vertical and horizontal axes, considering all of the six targets studied (P \u3c 0.05). Except for the distal segment of the ipsilateral sylvian fissure, no practical differences in the limits of the exposure were detected. CONCLUSION: The mini-SO approach may offer a similar surgical working area compared with that provided by standard craniotomies and constitutes an excellent alternative to the OZ and PT craniotomies in selected patients. Selection should not be based primarily on the area to be exposed, but rather on the working angles that are anticipated to be required. The key point is to use the most adequate technique for a particular patient, rather than using a one-size-fits-all approach for all patients. Copyright © by the Congress of Neurological Surgeons

Quantitative analysis of the working area and angle of attack for the retrosigmoid, combined petrosal, and transcochlear approaches to the petroclival region

Object. The authors quantitatively assessed the working areas and angles of attack associated with retrosigmoid (RS), combined petrosal (CP), and transcochlear (TC) craniotomies. Methods. Four silicone-injected cadaveric heads were bilaterally dissected using three approaches progressing from the least to the most extensive. Working areas were determined using the Optotrak 3020 system on the upper and middle thirds of the petroclivus and brainstem. Angles of attack were studied using the Elekta SurgiScope at the Dorello canal and the origin of the anterior inferior cerebellar artery (AICA). The TC approach provided significantly greater (p \u3c 0.001) working areas at the petroclivus (755.6 ± 130.1 mm 2) and brainstem (399.3 ± 68.2 mm 2) than the CP (354.1 ± 60.3 and 289.7 ± 69.9 mm 2) and RS approaches (292.4 ± 59.9, 177.2 ± 54.2 mm 2, respectively). The brainstem working area associated with the CP approach was significantly larger (p \u3c 0.001) than that associated with the RS route. There was no difference in the petroclival working area comparing the CP and RS approaches (p = 0.149). The horizontal and vertical angles of attack achieved using the TC approach were wider than those of the CP and RS at the Dorello canal and the origin of the AICA (p \u3c 0.001). Conclusions. The CP approach offers a more extensive working area than the RS for lesions involving the anterolateral surface of the brainstem, but not for petroclival lesions. The TC approach provides the widest corridor, improving the working area and angle of attack to both areas, but hearing must be sacrificed and the facial nerve is at risk