Facet cysts in the subaxial cervical spine: Case series focused on radiological and histopathological findings with a scoping review.

BACKGROUND: Facet cysts in the subaxial cervical spine are a relatively rare cause of neuropathy. This case series aimed to investigate the radiological and histopathological features and surgical results of these lesions, and provide possible mechanisms of cyst development. METHODS: Thirteen subaxial cervical facet cysts in 12 patients were diagnosed on the basis of magnetic resonance imaging and computed tomography with facet arthrography. Surgical outcomes were evaluated according to the Japanese Orthopaedic Association scores for cervical myelopathy, or Tanaka's scores for cervical radiculopathy. These results were presented in combination with a scoping review of the literature. RESULTS: Seven cysts were found in the posteromedial region, and six in the posterolateral portion of the spinal canal. Computed tomography revealed degeneration of all involved facet joints. All patients underwent decompression, and the mean recovery rates of Japanese Orthopaedic Association scores and Tanaka's scores were 57.1% and 87.5%, respectively. Histopathologically, all cysts were continuous with the degenerated ligamentum flavum. In the scoping review, the patients' mean age was 65.1 years. The cysts were distributed as follows: 3.6% at C2-3, 10.7% at C3-4, 14.3% at C4-5, 5.4% at C5-6, 7.1% at C6-7, and 58.9% at C7-T1. The presenting symptoms were myelopathy (49.4%) and radiculopathy (50.0%). Radiologically, 55% and 45% of the cysts were of the posteromedial and posterolateral types. Of the patients, 76.9% underwent decompression only, and 23.1% had concomitant fusion. Cyst recurrence was not observed in the mean follow-up period of 15.1 months. CONCLUSIONS: The pathogenesis of cysts is closely related to degenerative changes in the facet joint and ligamentum flavum, and rupture in degenerated ligaments can develop into a cavity, which contributes to cyst formation. The scoping review suggests that cyst resection generally results in positive outcomes without recurrence in either decompression alone or concomitant fusion.

Prevalence of pre-existing factors causing spinal cord compression: Is there a difference between patients suffering from cervical spinal cord injury with and without bone injury?

BACKGROUND: Recently, the prevalence of elderly patients suffering from cervical spinal cord injury (CSCI) without bone injury has been increasing in various countries. Pre-existing factors causing spinal cord compression, such as ossification of the posterior longitudinal ligament (OPLL), can increase the risk of CSCI without bone injury. However, no study has compared the prevalence of pre-existing factors between CSCI with and without bone injury. This study aimed to compare the prevalence of pre-existing factors between CSCI with and without bone injury. METHODS: In 168 consecutive patients with CSCI, pre-existing factors including OPLL, posterior spur of the vertebral body, developmental stenosis, disc bulge and calcification of yellow ligament (CYL) were evaluated on imaging studies. The prevalence of each type of pre-existing factors was compared between patients with and without bone injury. RESULTS: The prevalence of pre-existing factors in patients without bone injury (86%) was significantly higher than in those with bone injury (20%) (P < 0.001; odds ratio, 23.9). The most common pre-existing factor was OPLL followed by developmental stenosis, posterior spur, disc bulge and CYL in both groups. OPLL, development stenosis and posterior spur were significantly more common in patients without bone injury compared to those with bone injury (P < 0.01). CONCLUSIONS: Prevalence of pre-existing factors, such as OPLL, development stenosis and posterior spur was significantly higher in patients without bone injury than in those with bone injury. Thus, these pre-existing factors might be a potential risk of CSCI without bone injury.

Spontaneous thoracic spinal subarachnoid hemorrhage diagnosed with brain computed tomography.

Spontaneous thoracic spinal subarachnoid hemorrhage is rare, and thus no useful radiological findings for preoperative diagnosis have been reported. We experienced a patient with spontaneous thoracic spinal subarachnoid hemorrhage. A 37-year-old female presented with sudden-onset paraplegia and numbness in the trunk and bilateral lower extremities. The patient had no past history of trauma, lumbar puncture and bleeding disorder. T2-weighted sagittal magnetic resonance imaging (MRI) of the cervical and thoracic spines showed a mass occupied in the ventral space of spinal cord that was dorsally shifted. The mass extended from C6 to Th6 levels, with its largest size at Th2 level. Thoracic spine T2-weighted sagittal and axial MRI showed that the mass compressed spinal cord and was located in the intradural space. There was no spinal cord tumor and no spinal vascular malformation around the mass. Brain computed tomography (CT) showed a high-density area in the subarachnoid space, indicating the possibility of subarachnoid hemorrhage. Brain MRI showed no ruptured aneurysm. The patient was diagnosed as a spontaneous thoracic spinal subarachnoid hemorrhage and emergency surgery was selected. We performed right-side hemilaminectomy at Th1-Th6 and opened dura mater and arachnoid membrane. Hematoma was found in the ventral space of spinal cord and was removed. One year after surgery, numbness in the trunk and bilateral lower extremities had disappeared but paraplegia remained unchanged. Thoracic spine T2-weighted MRI confirmed no hematoma but showed a newly formed intradural cyst. Preoperative combination of brain CT and thoracic MRI is useful to diagnose thoracic spinal subarachnoid hemorrhage.

Operative treatment by external fixation for polyostotic fibrous dysplasia in the elbow joint. A case report.

Fibrous dysplasia is a condition in which normal skeletal bone changes into fibroblastic stroma and immature bone. We report our experience of a unilateral external fixator applied for the treatment of polyostotic fibrous dysplasia arising in the elbow. The patient was a 38 year-old man. His main complaint was left elbow pain and a mass, which increased in size. The histological diagnosis from the needle biopsy was fibrous dysplasia. An articulated unilateral external fixator was used for immobilization. The lesions in the left distal humerus and proximal ulna were curetted and cancellous bone was packed into the cavity. An external fixator (Elbow Fixator, Orthofix Inc., McKinney, USA) was applied from the proximal humeral shaft to the distal ulnar shaft for postoperative tentative immobilization and preservation of the affected elbow joint movement. At two years after the operation, the range of motion of the affected elbow was 90 degrees in flexion and -35 degrees in extension. The range of motion in pronation and supination of the left forearm was normal. No evidence of recurrence was noted at two years after surgery. The merits of using an external fixator were: an earlier start of range of motion exercises, and a decrease in the risk of tumor dissemination.

Cellular and subcellular localization of EFA6C, a third member of the EFA6 family, in adult mouse Purkinje cells.

EFA6C is a third member of the EFA6 family of guanine nucleotide exchange factors (GEFs) for ADP-ribosylation factor 6 (ARF6). In this study, we first demonstrated that EFA6C indeed activated ARF6 more selectively than ARF1 by ARF pull-down assay. In situ hybridization histochemistry revealed that EFA6C mRNA was expressed predominantly in mature Purkinje cells and the epithelial cells of the choroid plexus in contrast to the ubiquitous expression of ARF6 mRNA throughout the brain. EFA6C mRNA was already detectable in the Purkinje cells at embryonic day 13, increased progressively during post-natal development and peaked during post-natal second week. In Purkinje cells, the immunoreactivity for EFA6C was localized particularly in the post-synaptic density as well as the plasma membranes of the cell somata, dendritic shafts and spines, while the immunoreactivity in their axon terminals in the deep cerebellar nuclei was very faint. These findings suggest that EFA6C may be involved in the regulation of the membrane dynamics of the somatodendritic compartments of Purkinje cells through the activation of ARF6.

Somatodendritic localization of the mRNA for EFA6A, a guanine nucleotide exchange protein for ARF6, in rat hippocampus and its involvement in dendritic formation.

EFA6A is a guanine nucleotide exchange protein (GEP) that can specifically activate ADP-ribosylation factor 6 (ARF6) in vitro. A recent study has demonstrated that ARF6 is involved in the dendritic formation of developing hippocampal neurons [Hernandez-Deviez et al. (2002) Nature Neurosci., 5, 623-624]. This study examined a potential role for EFA6A in hippocampal development in Wistar rats. Our results provided definitive evidence for somatodendritic localization of EFA6A mRNA in both cultured and in vivo hippocampal neurons by nonradioactive in situ hybridization. During postnatal development, EFA6A mRNA was dramatically increased and its dendritic localization was most evident between P7 and P14. In contrast, ARF6 mRNA was confined to the neuronal layers of the hippocampus throughout development. In addition, the overexpression of a GEP-defective mutant of EFA6A enhanced the dendritic formation of the primary hippocampal neurons. The present findings suggest that EFA6A is intimately involved in the regulation of the dendritic development of hippocampal neurons.