An endoscopic, cadaveric analysis of the roof of the fourth ventricle.

We performed endoscopic dissections of the roof of the fourth ventricle in eight fresh human cadaveric heads to characterize the endoscopic anatomy of the roof of the fourth ventricle and the anatomical configuration of the structures forming its roof. We also made three-dimensional (3D) silicone casts of the fourth ventricle in seven formalin-fixed specimens to evaluate the 3D configuration of the structures that create the roof of the fourth ventricle. The roof of the fourth ventricle can be divided into three zones. The upper zone is formed by the superior cerebellar peduncle and superior medullary velum and is associated with the lingula. The middle zone is formed by the inferior cerebellar peduncles and inferior medullary velum and is associated with the nodule in the midline and with the peduncle of the flocculus. The lower zone is formed by the tela choroidea and is associated with the tonsils. The 3D shape of the roof the fourth ventricle resembles that of a rhomboid-based pyramid; the edges of the base represent the borders of the ventricle, and the apex is the cerebellar fastigium. The lateral recess is shaped like a triangular-based pyramid, with its base connected to the cavity of the fourth ventricle and its tip opening into the lateral cerebellomedullary cistern through the foramen of Luschka. Our results may help in the endoscopic exploration of and microsurgical approaches to the fourth ventricle through its roof.

Microscopic and endoscopic anterior communicating artery complex anatomy as seen through keyhole approaches.

The purpose of this anatomical study is to illustrate the microscopic and endoscopic anatomy of the anterior communicating artery complex as viewed through three keyhole approaches (keyhole pterional, lateral supraorbital and supraorbital) and to compare them. Each approach was carried out once on each side in five glutaraldehyde-fixed human cadaveric heads. A microscope and microscope-endoscope combination were used to grade access and visualization of the structures qualitatively using a previously published surgical exposure grading system. All three approaches provided good access and visualization of ipsilateral structures in the anterior communicating artery complex, but the pterional keyhole and the lateral supraorbital approaches gave the best access. Exposure of contralateral structures was limited overall, but was enhanced somewhat by the use of the endoscope.

Iatrogenic sciatic nerve injuries at buttock and thigh levels: the Louisiana State University experience review.

OBJECTIVE: To provide an overview of iatrogenic sciatic nerve injuries at the buttock and thigh levels, and to analyze results of the treatment provided at Louisiana State University Health Sciences Center-New Orleans. METHODS: The data from 196 patients were reviewed retrospectively. All patients had iatrogenic sciatic nerve injuries at the buttock and thigh levels and were evaluated and treated at the Louisiana State University Health Sciences Center between the years 1968 and 1999. One hundred sixty-four of these patients had injuries caused by injections at the buttock level, 15 sustained sciatic nerve injuries after a total hip arthroplasty, and 17 had iatrogenic damage at the thigh level. RESULTS: Patients with severe motor deficits underwent neurolysis if they had positive nerve action potentials, and end-to-end anastomosis or grafting if the nerve action potentials were negative. Operations were performed on 64 patients with injection injuries at the buttock level, on 15 with iatrogenic damage at the thigh level, and on 15 with deficits after total hip arthroplasty. Results were analyzed by the procedure performed and by the outcome in both the peroneal and tibial divisions. CONCLUSION: Patients with mild or no motor deficits and those with pain that was manageable did not undergo surgery and were treated conservatively. For patients with significant motor deficits and those with pain that was not responsive to pharmacological management, physical and occupational therapy required surgical intervention. Patients who had positive nerve action potentials required neurolysis only and had the best recovery, whereas those with negative nerve action potentials required more extensive intervention entailing reanastomosis or grafting and had worse outcome. In general, the outcome was better for the tibial than for the peroneal divisions, regardless of the type of intervention.