Time-Spatial Labeling Inversion Pulse Magnetic Resonance Imaging of Cystic Lesions of the Spinal Cord.

BACKGROUND: Cystic lesions of the spinal cord such as spinal intradural arachnoid cysts (SIACs) and spinal extradural arachnoid cysts (SEACs) contain cerebrospinal fluid (CSF). The pathology of these lesions is often difficult to understand because it is difficult to detect abnormal CSF flow by conventional magnetic resonance imaging (MRI) or myelography. We preliminarily evaluated the usefulness of time-spatial labeling inversion pulse magnetic resonance imaging (T-SLIP MRI) of cystic lesions of the spinal cord. METHODS: T-SLIP MRI was applied to the following 6 consecutive cystic lesions of the spinal cord: 3 SEACs, 1 SIAC, 1 spinal intramedullary cyst associated with adhesive arachnoiditis, and 1 chronic pseudomeningocele. Information obtained by T-SLIP MRI was evaluated with regard to the following: 1) whether exclusive pathologic information was obtained, 2) whether this information affected the therapeutic strategy, and 3) the time required for T-SLIP MRI. RESULTS: Exclusive information was obtained in all 6 cases. In SEACs and the intramedullary cyst, pathologic CSF flow into the cyst was directly visualized, enabling us to narrow the therapeutic intervention targets. In SIAC, exclusive information involved detection of the cystic cranial wall and the absence of the caudal wall, enabling us to omit the exploration of the caudal wall. The examination required as long as 80 minutes for SIAC and <30 minutes for the other cases. CONCLUSIONS: T-SLIP MRI is useful for obtaining pathologic information about cystic lesions of the spinal cord.

Detection of the communicating hole(s) of spinal extradural arachnoid cysts using time-spatial labeling inversion pulse magnetic resonance imaging.

STUDY DESIGN: Report of 2 cases. OBJECTIVE: To report the usefulness of time-spatial labeling inversion pulse magnetic resonance imaging (T-SLIP MRI) for detection of the communicating hole(s) of spinal extradural arachnoid cysts (SEACs). SUMMARY OF BACKGROUND DATA: SEACs normally communicate with the subarachnoid space via small communicating hole(s) in the dura. It is necessary to identify the accurate locations of these communicating hole(s) before attempting to close them through limited laminotomy/laminectomy. Myelocomputed tomography or conventional MRI may fail to detect the locations of the hole(s) because they comprise small dural defects. METHODS: Case 1: A 33-year-old female presented with an SEAC at the T11­L2 vertebral level. Case 2: An 82-year-old female presented with an SEAC at T12­L4 vertebral level. RESULTS: Case 1: T-SLIP MR image of the left parasagittal plane (not the midsagittal or right parasagittal plane) revealed cerebrospinal fluid flow from the subarachnoid space into the cyst at L1. After limited laminotomy at T12­L1 and partial cyst resection, we identified 2 contiguous dural holes immediately medial to the left L1 pedicle; this corroborated the preoperative T-SLIP MRI findings. The holes were sutured. Postoperative conventional MR image confirmed significant cyst shrinkage. Case 2: T-SLIP MR image revealed a curved line at the L1 pedicle in the right parasagittal plane. After L1 laminectomy and partial cyst resection, a dural hole was identified L1 pedicle, which was in agreement with the preoperative T-SLIP MRI findings. After surgery, the lower extremity pain disappeared. Postoperative conventional MR image revealed significant cyst shrinkage. CONCLUSION: T-SLIP MRI is useful for detection of the communicating hole(s) of SEACs. LEVEL OF EVIDENCE: N/A.

Age-related effects of cocultured rat nucleus pulposus cells and macrophages on nitric oxide production and cytokine imbalance.

STUDY DESIGN: A study of age-related effects on nitric oxide (NO) and cytokine production in cocultured rat nucleus pulposus (NP) cells and macrophages. OBJECTIVE: To evaluate the effects of age on NO and cytokine production in an in vitro model of cocultured NP cells and macrophages. SUMMARY OF BACKGROUND DATA: It is well known that the clinical characteristics of lumbar disc herniation differ with age. The relationship between age-related differences in clinical features and immuno-chemical factors, such as NO and inflammatory cytokines, has not been established. METHODS: Male Sprague Dawley rats (n = 45), including 15 animals from 3 groups (3-, 12-, and 32-weeks old), were used. NP cells and exudated peritoneal macrophages were cocultured in serum-free media. NO levels were measured at 2-, 24-, 48-, and 72 hours using the Griess method. After 7 days of culture, the production of cytokines, including tissue inhibitor metalloproteinase-1, interferon-gamma (IFN-gamma), and interleukin-10 (IL-10) were evaluated. RESULTS: NO levels of coculture increased with age. In the coculture groups, tissue inhibitor metalloproteinase-1 and IFN-gamma level of 3 weeks old were statistically higher than 12 and 32 weeks old. IL-10 level of 3 weeks old was statistically lower than 12 and 32 weeks old. CONCLUSION: NO levels of cocultures increased with age that suggests inflammatory reactions increase with age. This study showed an age-related cytokine imbalance, as represented by levels of IFN-gamma and IL-10. Stress and aging are thought to affect the extracellular matrix and change the immunologic response. Younger rat NP cells had higher cell-mediated immunity activity, while the older rat had higher humoral immunity activity. These results demonstrate that age affects the immunologic response attributable to NP cells. Further studies are needed to elucidate the mechanism of this newly observed occurrence and to apply these findings clinically.

Hydroxyapatite-coating of pedicle screws improves resistance against pull-out force in the osteoporotic canine lumbar spine model: a pilot study.

BACKGROUND CONTEXT: In patients with spinal osteoporosis, the early achievement and maintenance of a biological bond between the pedicle screw and bone is important to avoid screw loosening complications. There are few reports of in vivo investigations involving biomechanical and histological evaluations in the osteoporotic spine. PURPOSE: To evaluate the effect of hydroxyapatite (HA)-coating on the pedicle screw in the osteoporotic lumbar spine and to investigate the relationship between resistance against the screw pull-out force and bone mineral density (BMD) of the vertebral body. STUDY DESIGN/SETTING: Mechanical and pathological investigations in the lumbar spine. METHODS: Two 24-month-old female beagle dogs were fed a calcium-free dog chow for 6 months after ovariectomy (OVX). BMD (in g/cm2) was measured by dual energy X-ray absorptiometry at pre-OVX and 6 months after OVX. Pedicle screws were placed from L1 to L6 at 6 months after OVX. Twenty-four pure titanium cortical screws (Synthes, #401-114) were used as pedicle screws (Ti-PS). Of these, 12 screws had HA-coating (HA-PS). The HA-PS screws were inserted into the right pedicles and the Ti-PS were inserted into the left pedicles. Ten days after this procedure, the lumbar spines were removed en bloc for screw pull-out testing and histological evaluation. RESULTS: The mean BMD value of the lumbar vertebrae 6 months after the OVX was 0.549+/-0.087 g/cm2, which was significantly less than the pre-OVX mean BMD of 0.603+/-0.092 g/cm2 (p < 0.001). The mean resistance against the pull-out force for the HA-PS was significantly greater at 165.6+/-26.5N than in the Ti-PS (103.1+/-30.2N, p < .001). The histological sections in the HA-PS clearly revealed new bone bonding with the apatite coating but only fibrous tissue bonding in the Ti-PS. CONCLUSIONS: The results of this study showed that the resistance to the pull-out force of HA-PS is 1.6 times that of Ti-PS. Furthermore, HA-PS has superior biological bonding to the surrounding bone, as early as 10 days after surgery in this osteoporotic spine model. Thus, in patients with osteoporosis, coating of the pedicle screw with HA may provide better stability and bonding between the pedicle screw and bone in the early postoperative period.