Dennis E. McDonnell

Minimally invasive spine technology and minimally invasive spine surgery: a historical review

The trend of using smaller operative corridors is seen in various surgical specialties. Neurosurgery has also recently embraced minimal access spine technique, and it has rapidly evolved over the past 2 decades. There has been a progression from needle access, small incisions with adaptation of the microscope, and automated percutaneous procedures to endoscopically and laparoscopically assisted procedures. More recently, new muscle-sparing technology has come into use with tubular access. This has now been adapted to the percutaneous placement of spinal instrumentation, including intervertebral spacers, rods, pedicle screws, facet screws, nucleus replacement devices, and artificial discs. New technologies involving hybrid procedures for the treatment of complex spine trauma are now on the horizon. Surgical corridors have been developed utilizing the interspinous space for X-STOP placement to treat lumbar stenosis in a minimally invasive fashion. The direct lateral retroperitoneal corridor has allowed for minimally invasive access to the anterior spine. In this report the authors present a chronological, historical perspective of minimal access spine technique and minimally invasive technologies in the lumbar, thoracic, and cervical spine from 1967 through 2009. Due to a low rate of complications, minimal soft tissue trauma, and reduced blood loss, more spine procedures are being performed in this manner. Spine surgery now entails shorter hospital stays and often is carried out on an outpatient basis. With education, training, and further research, more of our traditional open surgical management will be augmented or replaced by these technologies and approaches in the future.

Traumatic Atlanto-Occipital Dislocation in Children

Traumatic atlanto-occipital dislocation is seen in approximately 25% of fatal pediatric trauma. This was previously considered to be a rare and fatal entity, however with improvements in resuscitation in the field, many patients who previously might have died are now evaluated in the hospital. Treatment of atlanto-occipital instability is internal fixation. Many authors have advocated supplemental external immobilization with a halo vest. However, there are several circumstances where the application of a halo vest is undesirable. Thus a method of internal fixation and fusion that is rigid enough not to require supplemental external orthosis is necessary. We present 2 cases of atlanto-occipital dislocation which were treated with Locksley intersegmental tie bar occipital cervical fusion. Both patients achieved solid fusion without supplemental halo bracing, and made complete neurologic recoveries. Traumatic atlanto-occipital dislocation is a potentially survivable injury that requires aggressive resuscitation in the field, a high index of suspicion and early definitive surgical stabilization.

Pump-regulated lumbar subarachnoid drainage.

OBJECTIVE The diversion of cerebrospinal fluid (CSF) has been widely used in the prevention and treatment of CSF fistulae. A common method is the use of a lumbar drainage system. Although it is effective, several serious complications can develop, which can be avoided by regulating the flow of CSF with a standard intravenous infusion pump. TECHNIQUE We present a simple, inexpensive, and accurate method of flow-controlled lumbar subarachnoid drainage that minimizes patient discomfort and the unpredictability of a gravity-dependent system. This system uses a standard lumbar drain connected to an intravenous infusion pump to provide drainage of CSF in a constant and predictable manner. RESULTS A total of 42 patients from two institutions were treated with this method. CSF fistulae occurred secondary to trauma in 9 patients, after spinal surgery in 11 patients, after transsphenoidal surgery in 10 patients, and after cranial base surgery in 12 patients. Resolution of the fistula was attained in 36 of 42 patients. There were no deaths, no cases of deep venous thrombosis, and no incidence of meningitis. One patient developed tension pneumocephalus, and two patients developed headache with nausea and vomiting. All patients were ambulatory, and only three patients required narcotic analgesia for headaches. CONCLUSION Pump-regulated lumbar subarachnoid drainage is safe and effective in the treatment of CSF fistulae, as reported elsewhere in the literature. The advantage of this method is that the drainage of CSF can be carefully controlled and titrated in a predictable fashion. Because the system is independent of gravity to produce drainage of CSF, patients are not confined to bed and serious complications of overdrainage can be avoided.

An evaluation and comparison of intraventricular, intraparenchymal, and fluid-coupled techniques for intracranial pressure monitoring in patients with severe traumatic brain injury.

ObjectiveIntracranial pressure measurements have become one of the mainstays of traumatic brain injury management. Various technologies exist to monitor intracranial pressure from a variety of locations. Transducers are usually placed to assess pressure in the brain parenchyma and the intra-ventricular fluid, which are the two most widely accepted compartmental monitoring sites. The individual reliability and inter-reliability of these devices with and without cerebrospinal fluid diversion is not clear. The predictive capability of monitors in both of these sites to local, regional, and global changes also needs further clarification. The technique of monitoring intraventricular pressure with a fluid-coupled transducer system is also reviewed. There has been little investigation into the relationship among pressure measurements obtained from these two sources using these three techniques.MethodsEleven consecutive patients with severe, closed traumatic brain injury not requiring intracranial mass lesion evacuation were admitted into this prospective study. Each patient underwent placement of a parenchymal and intraventricular pressure monitor. The ventricular catheter tubing was also connected to a sensor for fluid-coupled measurement. Pressure from all three sources was measured hourly with and without ventricular drainage.ResultsStatistically significant correlation within each mon- itoring site was seen. No monitoring location was more predictive of global pressure changes or more responsive to pressure changes related to patient stimulation. However, the intraven- tricular pressure measurements were not reliable in the presence of cerebrospinal fluid drainage whereas the parenchymal measure- ments remained unaffected.ConclusionIntraparenchymal pressure monitoring provides equivalent, statistically similar pressure measurements when compared to intraventricular monitors in all care and clinical settings. This is particularly valuable when uninterrupted cerebrospinal fluid drainage is desirable.

Management of lesions involving the craniocervical junction

The craniocervical junction is a unique biomechanical interface that acts as a transition zone between the cranial base and the upper cervical spine. A clear understanding of the embryologic derivation and anatomic orientation of the osseus, ligamentous, and neural structures making up the craniocervical junction is imperative before embarking on the diagnosis and management of pathologic lesions affecting this region.