Journal of neurosurgery. Spine
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There is currently no biologic therapy to repair or restore a degenerated intervertebral disc. A potential solution may rest with embryonic stem cells (ESCs), which have a potential to grow indefinitely and differentiate into a variety of cell types in vitro. Prior studies have shown that ESCs can be encouraged to differentiate toward specific cell lineages by culture in selective media and specific growth environment. Among these lineages, there are cells capable of potentially producing nucleus pulposus (NP) in vivo. In this investigation, the authors studied ESCderived chondroprogenitors implanted into a degenerated disc in a rabbit. For this purpose, a rabbit model of disc degeneration was developed. ⋯ This study illustrates a reproducible percutaneous model for studying disc degeneration. New notochordal cell populations were seen in degenerated discs injected with ESCs. The lack of immune response to a xenograft of mouse cells in an immunocompetent rabbit model may suggest an as yet unrecognized immunoprivileged site within the intervertebral disc space.
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Review Case Reports
Isolated unilateral hypoglossal nerve palsy secondary to an atlantooccipital joint juxtafacet synovial cyst.
Juxtafacet cysts of the atlantooccipital joint that present with isolated hypoglossal nerve palsy are rare and may mimic more common pathological entities. The authors report on the third such case in the literature and discuss the differential diagnosis, imaging hallmarks, preoperative recognition, and surgical management of this lesion, and provide a review of the literature. The authors discuss their experience with the treatment of a 67-year-old woman who presented with an isolated hypoglossal nerve palsy caused by a nonenhancing cystic septated lesion abutting the lateral medulla just medial to the left hypoglossal canal. ⋯ Failure to recognize this rare entity preoperatively resulted in unnecessary intradural exploration and cranial nerve morbidity. In retrospect, the preoperative diagnosis of this lesion was suggested by lack of central enhancement, absence of dumbbell formation and the presence of erosive synovial changes. Regardless, the extreme rarity of this lesion at this location will always make its recognition challenging.