Patrick W. Hitchon

Diagnosis and management of pyogenic vertebral osteomyelitis in adults

Management of vertebral osteomyelitis remains controversial regarding optimum duration of antibiotic therapy and the role of surgery. Forty adults with vertebral osteomyelitis were reviewed. Staphylococcus aureus was the most common pathogen isolated. Disk space narrowing with end-plate erosion was the earliest finding, followed by progressive vertebral body destruction. Magnetic resonance imaging proved extremely valuable in detecting spinal cord compression in patients with neurologic deficit. Treatment should include at least 8 weeks of intravenous antibiotics combined with immobilization for pain reduction. Surgical intervention is indicated for all patients with neurologic deficit. Serial erythrocyte sedimentation rates are valuable for following response to therapy. The value of magnetic resonance imaging in diagnosis is emphasized.

Alterations in Cerebral Blood Flow, Oxygen Metabolism, and Electrical Activity Produced by High Dose Sodium Thiopental

High dose barbiturate therapy is being used with increasing frequency in the management of a widening spectrum of neurological disorders. Accurate regulation of the barbiturate dose is essential to maximize cerebral vasoconstriction and reduce brain metabolism while avoiding the cardiovascular depressant side effects of the drug. The purpose of this study was to determine whether the electroencephalogram (EEG) could be used to regulate administration of the agent. In nine mongrel dogs cerebral blood flow (CBF) was determined using the radioactive microsphere technique. After the determination of control CBF, a slow infusion of sodium thiopental was begun. CBF determinations were repeated when the periods of burst suppression in the EEG over several minutes averaged 30, 60, 120, and 240 seconds. CBF and oxygen metabolism showed a nearly identical pattern of a precipituos drop from control levels reaching a plateau at burst suppression between 30 and 60 seconds. Changes in cerebrovascular resistance were of a similar but opposite nature. Significant increases in heart rate occurred with burst suppression of 30 seconds, whereas the arterial pressure and cardiac index decreased with burst suppression between 30 and 60 seconds. In this study cerebral metabolic depression and vasoconstriction from sodium thiopental reached a plateau when sufficient barbiturate was administered to produce EEG burst suppression of between 30 and 60 seconds. At this level there was no important cardiovascular depression. Administration of additional barbiturates significantly decreased systemic arterial pressure and cardiac output, but produced no further decrement in the cerebral metabolic rate of oxygen or the CBF. There was no predictable relationship between cerebral metabolism or cardiovascular function and blood levels of sodium thiopental.

Response of intractable pain to continuous intrathecal morphine: a retrospective study

&NA; We have treated 37 patients with intractable pain (35 with cancer‐related pain) by continuous intrathecal morphine infusion via implanted pump. These patients were carefully selected according to specific criteria, and each demonstrated a significant reduction in pain following a test dose of intrathecal morphine. All patients had good pain relief from intrathecal morphine infusion, even with pain located in cervical dermatomes. Systemic narcotics could be withdrawn from most patients. Significant side effects were rare and typically self‐limited. Many patients required gradually increasing doses, seemingly related to disease progression. Two patients with non‐malignant pain have had variable dose requirements over 28 and 44 months without clear tolerance. In these patients we observed a reduction in side effects associated with systemic opioids when continuous intrathecal opioid infusion was instituted. Intrathecal opioid administration may have fewer complications than ablative pain relief procedures. In properly selected patients, this method offers an effective alternative for pain relief.

Initial clinical experience with frameless stereotactic radiosurgery: Analysis of accuracy and feasibility

PURPOSE To report on preliminary clinical experience with a novel image-guided frameless stereotactic radiosurgery system. METHODS AND MATERIALS Fifteen patients ranging in age from 14 to 81 received radiosurgery using a commercially available frameless stereotactic radiosurgery system. Pathologic diagnoses included metastases (12), recurrent primary intracranial sarcoma (1), recurrent central nervous system (CNS) lymphoma (1), and medulloblastoma with supratentorial seeding (1). Treatment accuracy was assessed from image localization of the stereotactic reference array and reproducibility of biteplate reseating. We chose 0.3 mm vector translation error and 0.3 degree rotation about each axis as the maximum tolerated misalignment before treating each arc. RESULTS The biteplates were found on average to reseat with a reproducibility of 0.24 mm. The mean registration error from CT localization was found to be 0.5 mm, which predicts that the average error at isocenter was 0.82 mm. No patient treatment was delivered beyond the maximum tolerated misalignment. The radiosurgery treatment was delivered in approximately 25 min per patient. CONCLUSION Our initial clinical experience with stereotactic radiotherapy using the infrared camera guidance system was promising, demonstrating clinical feasibility and accuracy comparable to many frame-based systems.

The role of radiation therapy in the management of ependymomas of the spinal cord

Twenty patients with biopsy-proven ependymomas of the spinal cord were treated between 1960 and 1984-7 with surgery only, 3 with radiation therapy only, and 10 with surgery and postoperative radiation therapy. Of these, 2 patients developed recurrent tumor at the primary site, 3 developed a recurrent tumor in the thecal sac, and 1 developed distant metastasis. The absolute 5- and 10-year survival rates were 95% (19/20) and 86% (12/14), respectively. None of 13 patients who were treated with radiation therapy only or combined surgery and postoperative radiation therapy developed recurrent tumor at the primary site, and none of 7 patients who received thecal sac irradiation developed thecal sac recurrences. In contrast, 2 of 7 patients (29%) treated with surgery alone developed recurrent tumor at the primary site, and 3 of 13 patients (23%) who received no thecal sac irradiation developed a recurrent tumor in the thecal sac. The failure rates following surgery were greatest in patients who had tumor removed in a piecemeal fashion (43%, 6/14). The results show that radiation therapy is probably not necessary if the tumor has been removed completely in an en bloc fashion. However, radiation therapy is needed if the tumor has been incompletely removed or removed in a piecemeal fashion. If the tumor has been removed in a piecemeal fashion, the radiation portals should be extended to include the thecal sac. Histologic subtypes influenced the pattern of recurrence. Myxopapillary ependymomas and high grade cellular ependymomas appear to be more likely to recur in the thecal sac. However, no big difference could be detected in local recurrence.

Treatment options in primary Ewing's sarcoma of the spine: report of seven cases and review of the literature.

Primary Ewings sarcoma of the spine is reviewed, and seven cases are presented. Ewings sarcoma of the spine is a rare condition that appears with a clinical triad of local pain, neurological deficit, and a palpable mass. The clinical picture, imaging characteristics, and management are discussed. The definitive management of Ewings sarcoma of the spine, as in other locations, could include three main modalities: surgery, radiotherapy, and combination chemotherapy. In the presence of acute neurological decompensation, decompressive surgery via an appropriate approach should be performed. Because Ewings sarcoma is usually sensitive to chemotherapy, initial chemotherapy, in neurologically stable patients, could be attempted first without surgical resection. Further management could then be gauged according to the response.

Autograft-derived spinal cord mass following olfactory mucosal cell transplantation in a spinal cord injury patient

Over the last decade, human cell transplantation and neural stem cell trials have examined the feasibility and safety of these potential therapies for treatment of a variety of neurological disorders. However, significant safety concerns have surrounded these trials due to the possibility of ectopic, uncontrolled cellular growth and tumor formation. The authors present the case of an 18-year-old woman who sustained a complete spinal cord injury at T10-11. Three years after injury, she remained paraplegic and underwent olfactory mucosal cell implantation at the site of injury. She developed back pain 8 years later, and imaging revealed an intramedullary spinal cord mass at the site of cell implantation, which required resection. Intraoperative findings revealed an expanded spinal cord with a multicystic mass containing large amounts of thick mucus-like material. Histological examination and immunohistochemical staining revealed that the mass was composed mostly of cysts lined by respiratory epithelium, submucosal glands with goblet cells, and intervening nerve twigs. This is the first report of a human spinal cord mass complicating spinal cord cell transplantation and neural stem cell therapy. Given the prolonged time to presentation, safety monitoring of all patients with cell transplantation and neural stem cell implantation should be maintained for many years.

Solitary spinal plasmacytomas: management and outcome.

Nine patients with solitary plasmacytoma of the spine were reviewed. Four of these patients progressed to multiple myeloma within 9 +/- 4 months (mean +/- SD) from diagnosis, and died from their disease in 23 +/- 15 months. In contrast to this, the five remaining patients free of systemic disease or local recurrence survived 78 +/- 66 months. No correlation was found between age at diagnosis, lesion location, symptomatology, laboratory studies, surgical treatment, or radiation dosage and progression to systemic disease. Solitary plasmacytoma will progress to systemic multiple myeloma and death in approximately 50% of patients. The remaining patients exhibit long-term survival following local treatment of the solitary lesion.

Flexion-distraction injuries of the thoracolumbar spine: open fusion versus percutaneous pedicle screw fixation

OBJECT Flexion-distraction injuries occur due to distractive forces causing disruption of the posterior and middle spinal columns. These fractures classically consist of a fracture line through the posterior bony elements; involvement of the posterior ligamentous complex is, however, common. Surgical treatment is often required for these unstable injuries to avoid neurological deterioration and posttraumatic kyphosis, and the surgery traditionally consists of an open posterior approach with instrumented fusion. Percutaneous pedicle screw fixation for these injuries, with the goal of minimal tissue disruption and preservation of normal anatomy while achieving adequate stabilization, has recently been reported in the literature, but to date, a direct comparative study comparing open and percutaneous fixation has not been reported. The authors report their experience treating these fractures with both techniques and review the available literature. METHODS Patients with flexion-distraction injury who were treated between May 2003 and March 2013 were prospectively followed. American Spinal Injury Association scores and degree of kyphotic angulation were recorded at admission, discharge, and follow-up. Data regarding intraoperative blood loss and operative time were obtained from a chart review. Patients treated with open versus minimally invasive procedures were compared. RESULTS The authors identified 39 patients who suffered flexion-distraction injuries and were treated at their institution during the specified period; one of these patients declined surgery. All had injury to the posterior ligamentous complex. Open surgical procedures with pedicle screw fixation and posterolateral fusion were performed in 27 patients, while 11 patients underwent minimally invasive pedicle screw placement. Overall, there was improvement in kyphotic angulation at the time of discharge as well as most recent follow-up in both the open surgery and minimally invasive surgery (MIS) groups. The authors found no significant difference in American Spinal Injury Association score or the degree of kyphotic angulation between the MIS and open surgery groups. There was a trend toward shorter operative time for the MIS group, and patients who underwent minimally invasive procedures had significantly less blood loss. CONCLUSIONS Minimally invasive percutaneous pedicle screw fixation appears to have similar efficacy in the treatment of flexion-distraction injuries and it allows for reduced blood loss and tissue damage compared with open surgical techniques. Therefore it should be considered as an option for the treatment of this type of injury.

Biomechanical studies on two Anterior Thoracolumbar implants in cadaveric spines

STUDY DESIGN A biomechanical comparison of two commonly used anterior spinal devices: the Smooth Rod Kaneda and the Synthes Anterior Thoracolumbar Spinal Plate. OBJECTIVES To compare the stability imparted to the human cadaveric spine by the Smooth Rod Kaneda and Synthes Anterior Spinal Plate, and to assess how well these devices withstand fatigue and uni- and bilateral facetectomy. SUMMARY OF BACKGROUND DATA Biomechanical studies on the aforementioned and similar devices have been performed using synthetic, porcine, calf, or dog spines. As of the time of this writing, studies comparing anterior spinal implants using human cadaveric spines are scarce. METHODS An L1 corpectomy was performed on 19 spines. Stabilization was accomplished by an interbody wooden graft and the application of the Smooth Rod Kaneda in 10 spines and the Synthes Anterior Spinal Plate in the remaining 9. Biomechanical testing of the spines was performed in six degrees of freedom before and after stabilization, and after fatiguing to 5000 cycles of +/- 3 Nm of flexion and extension. Testing was repeated after uni- and bilateral facetectomy. RESULTS After stabilization, the Smooth Rod Kaneda was significantly more rigid than the anterior thoracolumbar bar spinal plate in extension. After fatigue, the Smooth Rod Kaneda was significantly stiffer than the anterior thoracolumbar spinal plate in flexion, extension, right lateral bending, left lateral bending, and right axial rotation. A significant decrease in stiffness was noted with the Synthes device in flexion after bilateral facetectomy compared with the stabilized spine. CONCLUSIONS The smooth Rod Kaneda device tends to be stiffer than the anterior thoracolumbar spinal plate, particularly in extension, exceeding the anterior thoracolumbar spinal plate in fatigue tolerance. The spine stabilized with the anterior thoracolumbar spinal plate is more susceptible to the destabilizing effect of bilateral facetectomy than than that stabilized with the Smooth Rod Kaneda. The additional rigidity encountered with the Smooth Rod Kaneda must be weighed against the simplicity of anterior thoracolumbar spinal plate application.