Howard B. Levene

Energy metabolism of intervertebral disc under mechanical loading

Intervertebral disc (IVD) degeneration is closely associated with low back pain (LBP), which is a major health concern in the U.S. Cellular biosynthesis of extracellular matrix (ECM), which is important for maintaining tissue integrity and preventing tissue degeneration, is an energy demanding process. Due to impaired nutrient support in avascular IVD, adenosine triphosphate (ATP) supply could be a limiting factor for maintaining normal ECM synthesis. Therefore, the objective of this study was to investigate the energy metabolism in the annulus fibrosus (AF) and nucleus pulposus (NP) of porcine IVD under static and dynamic compressions. Under compression, pH decreased and the contents of lactate and ATP increased significantly in both AF and NP regions, suggesting that compression can promote ATP production via glycolysis and reduce pH by increasing lactate accumulation. A high level of extracellular ATP content was detected in the NP region and regulated by compressive loading. Since ATP can serve not only as an intra‐cellular energy currency, but also as a regulator of a variety of cellular activities extracellularly through the purinergic signaling pathway, our findings suggest that compression‐mediated ATP metabolism could be a novel mechanobiological pathway for regulating IVD metabolism.

Influences of Nutrition Supply and Pathways on the Degenerative Patterns in Human Intervertebral Disc.

Study Design. Investigation of the effects of the impairment of different nutritional pathways on the intervertebral disc degeneration patterns in terms of spatial distributions of cell density, glycosaminoglycan content, and water content. Objective. The aim of this study was to test the hypothesis that impairment of different nutritional pathways would result in different degenerative patterns in human discs. Summary of Background Data. Impairment of nutritional pathways has been found to affect cell viability in the disc. However, details on how impairment of different nutritional pathways affects the disc degeneration patterns are unknown. Methods. A 3D finite element model was used for this study. This finite element method was based on the cell-activity coupled mechano-electrochemical theory for cartilaginous tissues. Impairment of the nutritional pathways was simulated by lowering the nutrition level at the disc boundaries. Effects of the impartment of cartilaginous endplate-nucleus pulposus (CEP-NP) pathway only (Case 1), annulus fibrosus (AF) pathway only (Case 2), and both pathways (Case 3) on disc degeneration patterns were studied. Results. The predicted critical levels of nutrition for Case 1, Case 2, and Case 3 were around 30%, 20%, and 50% of the reference values, respectively. Below this critical level, the disc degeneration would occur. Disc degeneration appeared mainly in the NP for Case 1, in the outer AF for Case 2, and in both the NP and inner to middle AF for Case 3. For Cases 1 and 3, the loss of water content was primarily located in the mid-axial plane, which is consistent with the horizontal gray band seen in some T2-weighted magnetic resonance imaging (MRI). For the disc geometry used in this study, it was predicted that there existed a high-intensity zone (for Case 3), as seen in some T2-weighted MRI images. Conclusion. Impairment of different nutrition pathways results in different degenerative patterns. Level of Evidence: N/A

An unusual case of footdrop: Anterior disc herniation mimicking a nerve sheath tumor

OBJECTIVEExtreme lateral disc herniations are described. Usually, the herniated disc is described as being at the lateral edge of the neural foramen. Herniated discs that lodge beyond this location need to be included in the differential of retroperitoneal lesions impinging on nerve roots. CLINICAL PRESENTATIONA 76-year-old woman presented with left leg radicular symptoms, including footdrop and a retroperitoneal lesion. Given the location of the lesion and its distance from the edge of the neural foramen, the differential diagnosis favored a nerve sheath tumor. INTERVENTIONAn anterior retroperitoneal approach was taken. At the time of surgery, the lesion proved to be a herniated disc arising from the anterior surface of the L5-S1 disc space, medial to the psoas muscle. The disc herniation resulted in severe compression of the L5 nerve root as the root joined the lumbosacral plexus. This type of even more extreme lateral disc herniation is not widely reported. At this location, there are reports of clinicians confusing discs for tumors and occasionally tumors for discs. Given that some disc herniations are no longer visually adjacent to the foramen, perhaps extreme lateral disc herniation is not an ideal term. This individual case report is supplemented with a review of the literature on this rare condition with specific searches for disc, retroperitoneal, anterior herniation. CONCLUSIONUsing the term anterior disc herniation will aid clinicians in including herniated disc fragments in the differential diagnosis for lesions affecting nerve roots anterior to the spine in this retroperitoneal location.

A murine model of hypertonic saline as a treatment for acute spinal cord injury: effects on autonomic outcome

OBJECT spinal cord injury (SCI) continues to be a problem without a definitive cure. Research based on improved understanding of the immunological aspects of SCI has revealed targets for treating and ameliorating the extent of secondary injury. Hypertonic saline (HTS), a substance both easy to create and to transport, has been investigated as an immunologically active material that can be used in a clinically relevant interval after injury. In this pilot study, HTS was investigated in a murine model for its abilities to ameliorate secondary injury after a severe spinal cord contusion. METHODS female C57Bl/6 mice with severe T8-10 contusion injuries were used as the model subjects. A group of 41 mice were studied in a blinded fashion. Mice received treatments with HTS (HTS, 7.5%) or normal saline solution (NSS, 0.9%) at 2 discreet time points (3 and 24 hours after injury.) A separate group of 9 untreated animals were also used as controls. Animals were assessed for autonomic outcome (bladder function). In a group of 33 mice, histological assessment (cellular infiltration) was also measured. RESULTS bladder function was found to be improved significantly in those treated with HTS compared with those who received NSS and also at later treatment times (24 hours) than at earlier treatment times (3 hours). Decreased cellular infiltration in each group correlated with bladder recovery. CONCLUSIONS the increased effectiveness of later administration time of the more osmotically active and immunomodulatory substance (HTS) suggests that interaction with events occurring around 24 hours after injury is critical. These events may be related to the invasion of leukocytes peaking at 8-24 hours postinjury and/or the peak benefit time of subject rehydration.

Preoperative skin antisepsis with chlorhexidine gluconate versus povidone-iodine: a prospective analysis of 6959 consecutive spinal surgery patients

OBJECTIVE The aim of this study was to determine the efficacy of 2 common preoperative surgical skin antiseptic agents, ChloraPrep and Betadine, in the reduction of postoperative surgical site infection (SSI) in spinal surgery procedures. METHODS Two preoperative surgical skin antiseptic agents-ChloraPrep (2% chlorhexidine gluconate and 70% isopropyl alcohol) and Betadine (7.5% povidone-iodine solution)-were prospectively compared across 2 consecutive time periods for all consecutive adult neurosurgical spine patients. The primary end point was the incidence of SSI. RESULTS A total of 6959 consecutive spinal surgery patients were identified from July 1, 2011, through August 31, 2015, with 4495 (64.6%) and 2464 (35.4%) patients treated at facilities 1 and 2, respectively. Sixty-nine (0.992%) SSIs were observed. There was no significant difference in the incidence of infection between patients prepared with Betadine (33 [1.036%] of 3185) and those prepared with ChloraPrep (36 [0.954%] of 3774; p = 0.728). Neither was there a significant difference in the incidence of infection in the patients treated at facility 1 (52 [1.157%] of 4495) versus facility 2 (17 [0.690%] of 2464; p = 0.06). Among the patients with SSI, the most common indication was degenerative disease (48 [69.6%] of 69). Fifty-one (74%) patients with SSI had undergone instrumented fusions in the index operation, and 38 (55%) patients with SSI had undergone revision surgeries. The incidence of SSI for minimally invasive and open surgery was 0.226% (2 of 885 cases) and 1.103% (67 of 6074 cases), respectively. CONCLUSIONS The choice of either ChloraPrep or Betadine for preoperative skin antisepsis in spinal surgery had no significant impact on the incidence of postoperative SSI.

Percutaneous Drainage of Chronic Destructive Lumbar Osteomyelitis Abscess Via the Use of Bilateral Transpedicular Trocar Access

BACKGROUND Pyogenic spondylodiskitis is an infection of intervertebral disks and spinal vertebral bodies. Various minimally invasive approaches to the infected disk spaces/abscesses have been described for management of early stages of the infection. Patients with chronic occurrence present with extensive infection, neurologic deficits, and bone destruction. Such patients commonly have substantial medical comorbidities. Despite the increased risks of complications, they often are treated with open surgical approaches without minimally invasive options. We describe a bilateral transpedicular approach to vertebral body abscess in a chronically infected patient with intraoperative contiguous irrigation. CASE DESCRIPTION We present 2 cases, a 58-year-old man and a 61-year-old man, both with a diagnosis of vertebral osteomyelitis. Images of lumbar spine showed epidural abscess and adjacent vertebral body destruction. Because of their poor clinical condition and chronicity of disease, these patients underwent percutaneous bilateral transpedicular approach. CONCLUSION Patients in poor health and with chronic vertebral osteomyelitis may benefit from minimally invasive percutaneous transpedicular drainage and irrigation of the abscess, representing a minimally invasive and effective treatment alternative for these patients.