Edmund Frank

Traumatic atlantoaxial rotatory subluxation and dislocation.

Study Design This is a retrospective single-patient case report with a literature review. Objective To report on a neurologically intact adult with bilateral traumatic atlamoaxial rotatory subluxation/dislocation and associated facet fracture, and present a review of the literature. Summary of Background Data Unilateral rotatory dislocation is relatively common at the atlantoaxial articulation. On the contrary, atlantoaxial rotatory subluxation with bilateral facet dislocation is uncommon, particularly in adults. Periodic reports have appeared in the literature regarding this entity in children, but only two previous citations have involved adults. Methods The patient was followed-up through personal examination and chart review from initial presentation to 5 months after discharge. Results Closed reduction with cervical traction was followed by surgical fusion with stable repair and no neurologic deficits over 5 months follow-up. Conclusions Traumatic bilateral atlantoaxial rotatory subluxation is uncommon in adults. This probably is due to the unique biomechanical features of the atlantoaxial articulation and the probable lethality of injury to the adjacent medulla or vertebral arteries before presentation at the trauma center.

Fractures of the thoracolumbar spine sustained by soldiers in vehicles attacked by improvised explosive devices

Study Design. Retrospective analysis. Objective. To analyze the types of orthopedic spine fractures sustained by North Atlantic Treaty Organization soldiers when vehicles are attacked by improvised explosive devices (IEDs), with specific focus on the flexion-distraction type thoracolumbar fracture (Chance fracture). Summary of Background Data. Operation Enduring Freedom is the North Atlantic Treaty Organization’s effort in Afghanistan. IED attacks on armored vehicles are common and account for high proportion of soldiers’ deaths and injuries. Methods. Retrospective record review was accomplished on soldiers admitted to a military hospital with orthopedic spine fractures after IED attacks on vehicles from January 1, 2008 to May 15, 2008. Thoracolumbar fractures were classified using the McAfee classification system. Results. Twelve male patients with 16 thoracolumbar fractures were identified (3 patients with multiple fractures). The 16 thoracolumbar fractures included 6 flexion-distraction fractures in 5 patients (38%, 6/16: two T12, two L1, one L3, and one L4), 7 compression fractures in 5 patients (44%, 5/16; one T7, one T8, two L1, one L2, one L3, and one L4), and 3 burst fractures (19%, 3/16; two L1 and one L2). Conclusion. The incidence of flexion-distraction thoracolumbar (Chance) fractures has been reported to be between 1.0% and 2.5% in most spine fracture series. In this small study, Chance fractures represented 38% of all tho-racolumbar fractures sustained after IED attack on armored vehicles. The blast pattern associated with IED explosion may be responsible for the high rate of these injuries in vehicle occupants.

A technique for cervical laminoplasty using mini plates.

Accepted laminoplasty techniques may limit ones ability to decompress cervical nerve roots and the constructs may fail leading to restenosis of the cervical spinal canal. A simple laminoplasty technique has been developed using titanium miniplates that permits adequate decompression of the cervical spinal cord and bilateral cervical nerve roots, and successfully reconstructs an enlarged rigid spinal canal.

Endoscopic suction decompression of idiopathic epidural lipomatosis

BACKGROUND Epidural lipomatosis can be idiopathic or associated with obesity and steroid excess. This disorder can be treated by weight control, reduction of steroid load, or operative decompression. We describe a non-obese patient with neurogenic claudication who had localized epidural fat from L4 to S1. Minimally invasive treatment consisted of a small laminotomy and endoscopically guided fat aspiration. METHODS A small bilateral L5-S1 laminotomy was performed. Using a special malleable endoscopic aspirator, loose fat was removed both dorsal and ventral to the dural sac. RESULTS At surgery, endoscopically guided suction aspiration was successful in removing the majority of the fat. Areas of fat that were vascularized and adherent to the dura required microsurgical dissection. Postoperatively, the patient has been asymptomatic. CONCLUSIONS This minimally invasive technique was successful in treating epidural dual compression that had failed conservative measures. Further evaluation of this technology is warranted.

Assessing automobile head restraint positioning in Portland, Oregon

Objective: Automobile head restraints, when used properly, have been shown to decrease the incidence and severity of whiplash injuries to the neck. Before the development of a public campaign on proper head restraint positioning, the authors assessed head restraint positioning and public understanding. Design: Over a one month period, the position of the vehicle head restraint of drivers was observed in moving cars in the city of Portland, Oregon (population 530 000). Optimal position was defined as having the head restraint above the ears with the back of the head touching the head restraint. A questionnaire on head restraint understanding was administered to people during jury service. Results: Of the 4287 drivers observed, 1% (n = 30) had no head restraint on their seat, 4% (n = 158) had a fixed head restraint, and 95% (n = 4099) had an adjustable head restraint. Among the fixed head restraints, 21% (33/158) were positioned optimally with no horizontal gap. Among the adjustable head restraints, only 7% (280/4099) had optimal head restraint positioning. Overall, 93% (3974/4287) of all head restraints observed were suboptimally positioned. Seventy five percent (38/51) of polled Portland residents identified safety as the primary head restraint function. Conclusion: Ninety three percent of all head restraints observed were suboptimally positioned. Fixed head restraints were three times more likely to be in optimal position than adjustable head restraints (21% v 7%). Most polled Portland residents understood the proper function and positioning of head restraints. This discrepancy between actual practice and understanding should be addressed with public education and manufacturer design changes.

Cortical basic fibroblast factor expression after head injury: Preliminary results

Growth factors are important for normal development and maturation of the CNS. Recently, interest has centred on the role of these factors in response to the CNS injury. Basic Fibroblast Growth Factor (bFGF) stimulates mitogenesis of neuroectodermal tissues, potentially promoting neuronal survival and astrocytic growth suggesting a possible role following injury. We have studied expression of bFGF in male Sprague-Dawley rats subjected to a fluid percussion head injury of 4 atmospheres. Sham operated controls and injured animals were perfused 48 h after injury. 50 micron frozen sections of fixed tissue were immunohistochemically analysed for bFGF expression using the avidin-biotin complex technique with antibodies to bFGF. In the cortex, bFGF expression on astrocytes was enhanced in the injured hemisphere as compared with the contralateral uninjured hemisphere or controls (914 vs. 334 cells/mm2). bFGF expression in the hippocampal (CA2) neurons was the same for both normal and injured rats. The finding of enhanced bFGF in the cortex is consistent with the pathologic astrocytic responses found 48 h after injury and may correlate with later gliosis. These results suggest further study of bFGF, its temporal expression and relationship to other growth factors is warranted.

A Proposed Technique for Intraoperative Measurement of Cervical Spine Stiffness

OBJECTIVE Classically cervical biomechanical data have been obtained using cadaver models. Few methods exist for in vivo measurement of cervical biomechanics. A technique for intraoperative measurement of cervical motion segment stiffness (load-axial displacement) has been developed, enabling load/displacement data to be obtained during surgery at the spinal levels operated on and at adjacent cervical levels. METHODS The instrument used for measuring motion segment stiffness was a vertebral retractor equipped with displacement and strain transducers and designed to be placed over the shafts of Caspar distraction screws. Stiffness was measured under simulated anterior cervical surgical conditions. RESULTS A preliminary study deciphering axial cervical spine load/displacement data on 12 cadavers was performed with this instrument. Using a distraction load of 88.8640 N, axial displacements of 2.110 +/- 0.258 mm (mean +/- standard error of the mean) at C3-C4, 2.367 +/- 0.304 mm at C4-C5, and 2.207 +/- 0.238 mm at C5-C6 were found. When data were evaluated for age, there was a significant decrease in stiffness with advancing age in two of the three spinal segments tested (P < 0.05 for C3-C4, P < 0.04 for C4-C5, P < 0.12 for C5-C6), which correlated with previous studies. CONCLUSION These results suggest that this technique may be useful in assessing intraoperative motion-segment stability.

HLA-DR expression on arachnoid cells : a role in the fibrotic inflammation surrounding nerve roots in spondylotic cervical myelopathy

Study Design. Human arachnoid cells were examined immunohistochemically for expression of HLA-DR or Fc receptors. Objective. To assess the ability of arachnoid cells to express HLA-DR and act as antigen presenting cells. Summary of Background Data. An intradural inflammatory reaction surrounds the cervical nerve roots and radicular vessels in patients with spondylotic cervical myeloradiculopathy. Active arachnoid proliferation and fibrosis in this reaction suggest these cells are actively involved in this inflammatory process. An inflammatory response is initiated by an antigen presenting cell. Evidence suggests that arachnoid cells may be antigen presenting cells, like macrophages, because they can phagocytize foreign tissue and have immunoglobulin G and complement receptors. Methods. Spinal arachnoid obtained from patients undergoing spinal surgery for intramedullary processes was grown in culture. The arachnoid cells were characterized and examined immuohistochemically for the expression of HLA-DR and Fc receptors. Results. HLA-DR was expressed in vivo and in vitro by arachnoid cells. The macrophage Fc receptor was not expressed in vivo nor in vitro by arachnoid cells. Conclusion. Finding in vivo and in vitro HLA-DR expression on arachnoid cells adds further support to the concept that arachnoid cells have the potential to serve as antigen presenting cells. The absence of Fc receptors, although necessary for macrophages, does not negate antigen presenting function because other types of cells—e.g., endothelium—can present antigen without displaying Fc receptors. These experiments provide new evidence that arachnoid cells may initiate or sustain the intradural inflammatory reaction found in cervical myeloradiculopathy.

Magnetic resonance imaging analysis of extremely slow flow in a model shunt system.

Shunt malfunction is common and its diagnosis may require invasive testing that may be inaccurate or result in complications. Magnetic resonance imaging (MRI) may prove to be a useful noninvasive test of shunt function as it has been shown that MRI is capable of measuring cerebrospinal fluid (CSF) flows from 2 ml/h to 40 ml/h in model systems. Since flows in functioning shunt systems can be less than 2 ml/h, MRI must be sensitive enough to detect flow in this range in order to be a valid test for shunt function. Continuing previous studies, we have studied MRI flow-related enhancement at flow rates from 0 to 2 ml/h. Multiple spin echo scans (TR2000, TE20) were made through a specialized section of tubing in a model shunt system. The intensity of the MRI signal at points known to demonstrate maximal flow-related enhancement was measured. A linear relationship was demonstrated between signal intensity and flow as low as 0.8 ml/h. These results add support to the concept that MRI is sensitive enough to detect the lowest flows present in functioning shunt systems and therefore may be useful as a noninvasive test of shunt function.

An adjustable ventriculoscope guide for use with stereotactic frames.

A ventriculoscope guide intended for use with stereotactic frames is described. This guide allows the ventriculoscope to be moved freely and then fixed rigidly into position without readjustment of the stereotactic frame. This design address requirements for extremely strong fixation of the ventriculoscope, adaptability to most stereotactic systems, and minimal damage to the brain tissue traversed by the ventriculoscope.