Citations

ABSTRACT Background Facet Joint Septic Arthritis (FJSA) is an infection of the spinal facet joints, for which previously described imaging findings are non‐specific. We present MRI findings of 20 patients who underwent facet biopsy for possible FJSA. Materials and Methods An internal database was reviewed for cases who underwent image‐guided spinal facet biopsy for possible infection and had pre‐biopsy contrast‐enhanced MRI. Cases were categorized as biopsy FJSA positive or negative and MRI was reviewed for synovitis, bone marrow enhancement, epidural phlegmon/abscess, and paraspinal muscle enhancement. The MRI findings were considered extensive if the involvement of the posterior paraspinal muscles spanned at least two vertebral bodies in the craniocaudal direction and at least half the length of the muscles in the anterior‐posterior direction. Results Twenty patients were included. Nine patients were FJSA positive, all of whom had synovitis, bone marrow enhancement of the facet joints, and epidural phlegmon. No patients had epidural abscess, but five patients had a paraspinal abscess. All nine patients demonstrated extensive paraspinal muscular enhancement. Eleven biopsy cases that were negative for FSJA were included. Their MRI findings demonstrated all with synovitis, six with bone marrow enhancement of the facet joints, six with epidural phlegmon, none with epidural abscess, and none with paraspinal abscess. Only one FJSA negative case had extensive paraspinal muscle enhancement. Conclusion The MRI appearance of FJSA has rarely been described in the literature; however, the diagnosis has a significant clinical impact. Facet enhancement with florid posterior paraspinal muscle enhancement should raise suspicion for FSJA.

Accumulating pre-clinical data suggests that matrix metalloproteinase (MMP) expression plays a critical role in the pathophysiology of secondary brain injury. We conducted a prospective multimodal monitoring study in order to characterize the temporal MMP response after severe traumatic brain injury (TBI) in eight critically ill humans and its relationship with outcomes. High-cutoff, cerebral microdialysis ( n =8); external ventricular drainage ( n =3); and arterial and jugular venous bulb catheters were used to collect microdialysate, cerebrospinal fluid, and arterial and jugular bulb blood over 6 days. Levels of MMP-8 and -9 were initially high in microdialysate and then gradually declined over time. After these MMPs decreased, a spike in the microdialysate levels of MMP-2 and -3 occurred, followed by a gradual rise in the microdialysate concentration of MMP-7. Use of generalized estimating equations suggested that MMP-8 concentration in microdialysate was associated with mortality ( p =0.019) and neurological outcome at hospital discharge ( p =0.013). Moreover, the mean microdialysate concentration of MMP-8 was 2.4-fold higher among those who died after severe TBI than in those who survived. Mean microdialysate levels of MMP-8 also rose with increasing intracranial pressure (ICP), whereas those of MMP-7 decreased with increasing cerebral perfusion pressure (CPP). Significant changes in the mean microdialysate concentrations of MMP-1, -2, -3, and -9 and MMP-1, -2, -3, -7, and -9 also occurred with increases in microdialysate glucose and the lactate/pyruvate ratio, respectively. These results imply that monitoring of MMPs following severe TBI in humans is feasible, and that their expression may be associated with clinical outcomes, ICP, CPP, and cerebral metabolism.