Three-Dimensional Endoscopic Photography of Anatomic Specimens.

BACKGROUND/OBJECTIVE: Three-dimensional images have become an important tool in understanding surgical anatomy. This paper describes a simple method for obtaining endoscopic 3-dimensional anatomic images for teaching purposes. METHODS: This method uses a single endoscope that provides regular, two-dimensional images. Obtaining the three-dimensional image requires the superposition of two similar but slightly different images of the same object. The set of images, one mimicking the view of the left eye and the other mimicking the view of the right eye, constitute the stereoscopic pair of images obtained with the endoscope. To construct 3-dimensional images, the distance between the pictures must approximate the interpupillary distance. RESULTS: The technique involves fixing the endoscope in position using a self-retracting arm and placing the specimen on a simple sliding tray with an adapted millimeter scale to control the distance between the pictures. The initial still image is captured and the tray on which the specimen sits is shifted up to 3-4 mm laterally to capture the second image. As a general rule, one can calculate the distance between the pictures by moving the specimen laterally 1/30 of the distance between the lens and the object. Images captured are processed using anaglyphic technique for printing and horizontal-vertical polarization of light for presentation to larger audiences. CONCLUSIONS: Images produced in this way may aid in the understanding of the depth of different structures and ease of learning curve for the use of the endoscopy in neurosurgery.

Usefulness of the contralateral Omega sign for the topographic location of lesions in and around the central sulcus.

BACKGROUND: The central sulcus may be located through magnetic resonance imaging (MRI) by identifying the ipsilateral inverted Omega shape. In a brain with a lesion in this area, its identification becomes a hard task irrespective of the technique applied. The aim of this study is to show the usefulness of the contralateral Omega sign for the location of tumors in and around the central sulcus. We do not intend to replace modern techniques, but to show an easy, cheap and relatively effective way to recognize the relationship between the central sulcus and the lesion. METHODS: From July 2005 through December 2010, 43 patients with lesions in and around the central sulcus were operated using the contralateral Omega sign concept. Additionally, 5 formalin-fixed brains (10 hemispheres) were studied to clarify the anatomy of the central sulcus where the Omega shape is found. RESULTS: The central sulcus has three genua. The middle genu is characterized by an inverted Omega-shaped area in axial sections known as the Omega sign. On anatomical specimens, Omega was 11.2 ± 3.35 mm in height, on average, and 18.7 ± 2.49 mm in width, at the base. The average distance from the medial limit of the Omega to the medial edge of the hemisphere was 24.5 ± 5.35 mm. Identification of the Omega sign allowed for the topographic localization of the contralateral central sulcus in all our surgical cases but one. CONCLUSION: The contralateral Omega sign can be easily and reliably used to clarify the topographic location of the pathology. Hence, it gives a quick preoperative idea of the relationships between the lesion and the pre- and post-central gyri.

Endoscopic-assisted lateral transatlantal approach to craniovertebral junction.

BACKGROUND: The lateral approach to the craniocervical junction is directed along the atlantal and occipital condyles to the dens. The advantages of the lateral approach compared with the anterior transoral and transnasal approaches are that it provides a sterile field, and anterior decompression and postdecompression fixation can be performed in one procedure. OBJECTIVE: To examine the usefulness of endoscopy as an auxiliary tool during lateral transatlantal odontoidectomy. METHODS: Six cadaver heads, in which the vessels were injected with colored silicone, were dissected using a surgical microscope and 0- and 30-degree endoscopes. A flap incision was chosen to accomplish exposure of the area of the decompression, the occipital squama and adjacent laminae for fixation, and the vertebral artery from C2 to its dural entrance for its stabilization. RESULTS: Study findings revealed that endoscopy adds several advantages to microscopy in the lateral transatlantal approach to the craniovertebral junction in cases of craniovertebral malformation by providing magnification and illumination not limited by corners, thus helping to avert substandard decompression and complications such as dural tears and cerebrospinal fluid leaks; flexibility in surgical positioning of patients; and improved ergonomics that enable the surgeon to complete the procedure in a more efficient, comfortable, and safe manner. CONCLUSION: Endoscopy is a useful adjunct to microscopy in completing lateral approaches to the craniovertebral junction.