Etiology of post-uterosacral suspension neuropathies

INTRODUCTION AND HYPOTHESIS

The goal of our investigation was to find a neurological explanation for neuropathies reported following some uterosacral ligament suspension (USLS) [2-3].

METHODS

We dissected the neural structures beneath the USL in seven female, adult, embalmed cadavers. We made a literature review to determine the spinal nerve sensory fiber composition of each exposed neural structure and the dermatome(s) that it innervates. We then compared anticipated sensory neuropathies for each neural structure with neuropathies following USLS to determine which neural structure entrapment could explain the reported symptoms.

RESULTS

Several neural structures located beneath the uterosacral ligament (USL) are vulnerable to suture entrapment during USLS. Anticipated clinical outcomes of entrapments are discussed.

CONCLUSIONS

Entrapment of S2 sensory fibers in the second trunk of the sacral plexus or in the intrapelvic portion of the sciatic nerve is the most plausible etiology for reported neuropathies following USLS.

Identification and comparative analysis of a second runx3 promoter

The runx gene family encodes transcriptional regulators that are essential in several processes. Alternative transcription start sites (3' or P1 and 5' or P2) have been described both at runx1 and runx2. Functional domains have been mapped to P2 N-termini. Here, starting from an analysis of cDNA clones, we identify a P2 promoter at mouse runx3. In functional assays in COS-7 cells, this promoter is as active as runx1 P2. By nuclease protection, primer extension and deletion analysis we map a major start site and define a minimal promoter element. The activity of both promoters at all three mouse loci was systematically compared in a comprehensive panel of fresh tissues. The conservation of a two-promoter structure and their distinctive pattern of activity support the hypothesis that alternative 5' isoforms subserve unique functions.

Microanatomical variations in the cerebellopontine angle associated with vestibular schwannomas (acoustic neuromas): a retrospective study of 1006 consecutive cases

OBJECT

Great advances in neuroimaging, intraoperative cranial nerve monitoring, and microsurgical technique have shifted the focus of acoustic neuroma surgery from prolonging life to preserving cranial nerve function in patients. An appreciation of the vascular and cranial nerve microanatomy and the intimate relationship between neurovascular structures and the tumor is essential to achieve optimum results. In this paper the authors analyze the microanatomical variations in location of the facial and cochlear nerves in the cerebellopontine angle (CPA) associated with acoustic neuromas and, additionally, describe the frequency of involvement of surrounding neural and vascular structures with acoustic tumors of varying size. The authors base these findings on their experience with 1006 consecutive patients who underwent surgery via a retrosigmoid or translabyrinthine approach.

METHODS

Between July 1969 and January 1998, the senior author (D.M.L.) performed surgery in 1022 patients for acoustic neuroma: 705 (69%) via the retrosigmoid (suboccipital); 301 (29%) via the translabyrinthine; and 16 (2%) via the middle fossa approach. Patients undergoing the middle fossa approach were excluded from the study. The remaining 1006 patients were subdivided into three groups based on tumor size: Group I tumors (609 patients [61%]) were smaller than 2.5 cm; Group II tumors (244 patients [24%]) were between 2.5 and 4 cm; and Group III tumors (153 patients [15%]) were larger than 4 cm. The senior author's operative notes were analyzed for each patient. Relevant cranial nerve and vascular "involvement" as well as anatomical location with respect to the tumor in the CPA were noted. "Involvement" was defined as adherence between neurovascular structure and tumor (or capsule), for which surgical dissection was required to free the structure. Seventh and eighth cranial nerve involvement was divided into anterior, posterior, and polar (around the upper or lower pole) locations. Anterior and posterior locations were further subdivided into upper, middle, or lower thirds of the tumor. The most common location of the seventh cranial nerve (facial) was the anterior middle third of the tumor for all groups, although a significant number were found on the anterior superior portion. The posterior location was exceedingly rare (< 1%). Interestingly, patients with smaller tumors (Group I) had an incidence (3.4%) of the seventh cranial nerve passing through the tumor itself, equal to that of patients with larger tumors. The most common location of the eighth cranial nerve complex was the anterior inferior portion of the tumor. Not surprisingly, larger tumors (Group III) had a higher incidence of involvement of fourth cranial nerve (41%), fifth cranial nerve (100%), ninth-11th cranial nerve complex (99%), and 12th cranial nerve (31%), as well as superior cerebellar artery (79%), anterior inferior cerebellar artery (AICA) trunk (91.5%), AICA branches (100%), posterior inferior cerebellar artery (PICA) trunk (59.5%), PICA branches (79%), and the vertebral artery (VA) (93.5%). A small number of patients in Group III also had AICA (3.3%), PICA (3.3%), or VA (1.3%) vessels within the tumor itself.

CONCLUSIONS

In this study, the authors show the great variation in anatomical location and involvement of neurovascular structures in the CPA. With this knowledge, they present certain technical lessons that may be useful in preserving nerve function during surgery and, in doing so, hope to provide neurosurgeons and neurootologists with valuable information that may help to achieve optimum outcomes in patients.