Hajime Arai

Lateral Approach to Intraorbital Lesions: Anatomic and Surgical Considerations

OBJECTIVE We present our microsurgical lateral orbital approach for intraorbital lesions, with special emphasis on the microanatomy of the orbit. METHODS Among 26 patients, such lesions included tumors of the lacrimal glands, cavernous angioma, meningioma, neuroma, and other tumors. These intraorbital lesions were removed through a 35- to 40-mm lateral skin incision, and this was followed by lateral orbitotomy featuring a microsurgical dissecting technique. If it was necessary to gain access to the deep lateral portion of the muscle cone, the lateral orbitotomy was extended to the anterior temporal dura. There are two microsurgical routes into the muscle cone, one above and the other below the lateral rectus muscle. The structures encountered along these two routes were demonstrated in an anatomic study of the orbit in cadavers. RESULTS Lesions located in the lateral compartment of the orbit could be exposed through lateral orbitotomy and were completely removed in most cases. Complications in our series of 26 patients included one case of postoperative visual impairment, one case of tonic pupil, and three cases of transient impairment of eye movement. CONCLUSION We think that, with an intimate understanding of the anatomy of the orbit, intraorbital lesions located in the lateral compartment of the orbit, and even those in the lateral apex, can be safely removed through lateral orbitotomy.

Dandy-Walker Syndrome

The basic triad of Dandy-Walker syndrome (DWS) is the supratentorial hydrocephalus, the posterior fossa cyst, and dysgenesis of the cerebellar vermis. In this chapter, we review 37 cases of DWS treated at Cook County and Children’s Memorial Hospitals in Chicago between 1963 and 1977, and 26 cases of the posterior fossa cyst, including 2 cases of DWS, diagnosed at the Juntendo University Hospital in Tokyo since 1978. On the basis of these investigations, we present clinical, neuroradiological, and surgical features of DWS and offer a review of the literature.