Femoral nerve palsy following mini-open extraperitoneal lumbar approach: report of three cases and cadaveric mechanical study.

Anterior extraperitoneal exposures to the lumbar spine are being increasingly used owing to the expanding use of novel technologies to treat degenerative disc disease. Lumbar plexus injuries are potential, albeit uncommon, complications of such exposures and can lead to significant perioperative morbidity. In this report, we present three patients with thoracolumbar fractures who sustained isolated femoral nerve palsies after a mini-open extraperitoneal approach to the midlumbar spine was undertaken to perform a partial corpectomy. To further understand the pathophysiology of this nerve injury, we conducted a cadaveric experiment to evaluate the effect of performing this approach and the effect of hip positioning on linear displacement of the femoral nerve. The displacement of the femoral nerve during the anterolateral extraperitoneal exposure through a 4- to 6-cm incision was equal to 6.6% of the full femoral nerve length. Relaxation of the femoral nerve was equal to 25% of the full nerve length when the hip was flexed to 90 degrees in neutral abduction-adduction. We conclude that the anterolateral extraperitoneal exposure of the midlumbar spine can potentially stretch the femoral nerve beyond its physiologic limits, particularly in trauma cases where exposure of the lateral vertebral body necessitates substantial retraction of the psoas muscle. The avoidance of self-retaining retractors for prolonged periods of time and the positioning of the hip in flexion may help to avoid such nerve injuries.

Cervical venous organization in the transverse foramen.

The most widely accepted description of venous anatomy in the transverse foramen involves the presence of one or two veins running along and parallel to the external side of the vertebral artery. For most surgeons, the vertebral artery is surrounded by a rete of veins which is continous with the wide sinusoids which surround the thecal sac (internal vertebral venous plexus). The goal of this study was to ascertain the exact structure of the venous system in the transverse canal by micro dissection and histology. Six spinal segments (C1 to C7) removed from cadavers embalmed using 5% diluted formalin or not and studied with or without injection of colored latex after bilateral catheterization of the internal jugular vein, vertebral vein, common carotid artery, and vertebral artery. An anatomical study was performed by optical microscopy. After fixation and decalcification, tissue specimens were stained using hematoxylin-eosin-safran (HES) and immunocytochemical markers including CD43, CD31, and desmine (specific for vascular endothelium). Findings showed that venous blood in the transverse canal flows through a space formed by the periosteum. There was no evidence of a vein inside the transverse canal. The periosteum spans the space between the transverse processes and gives off fibrous leaflets to the artery thus forming a compartmentalized space lined with vascular endothelium around the artery. The venous system in the transverse canal presents itself as a sinus similar to the intracranial sinus structure.

Long-term control of vestibular schwannoma after a translabyrinthine complete removal.

OBJECTIVE: The goal of this study was to determine the rate of recurrent vestibular schwannoma after a total removal via the translabyrinthine approach. PATIENTS: Between 1973 and 1995, 346 patients were operated on by a translabyrinthine approach. Ninety-one patients were included in a retrospective study for follow-up of 5 years or longer. RESULTS: The mean follow-up period for magnetic resonance imaging (MRI) examination was obtained after mean of 11 years in 91 patients. None of the 91 patients experienced a recurrent vestibular schwannoma on MRI. CONCLUSION: The translabyrinthine approach is a safe procedure for total definitive removal of a vestibular schwannoma and permitted the absence of tumoral recurrence in our series of 91 patients. A single gadolinium-enhanced MRI scan 5 years after surgery is advised in case of total removal. In case of any doubt about the quality of the tumoral removal, a proposed MRI follow-up schedule within 2 years and 5 years of surgery is an initial baseline pattern, and possibly thereafter repeated MRI examinations on clinical grounds.