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Object: Embolization of intracranial aneurysms performed using Guglielmi detachable coils (GDCs) is performed with the patient in a state of general anesthesia at most centers. Such an approach does not allow intraprocedural evaluation of the patient's neurological status and carries additional risks associated with general anesthesia and mechanical ventilation. At the authors' institution, GDC embolization of intracranial aneurysms is performed in awake patients after administration of sedative and analgesic agents (midazolam, fentanyl, morphine, and/or hydromorphone). To determine the feasibility and safety of this approach, the authors have retrospectively reviewed their clinical experience., Methods: The authors reviewed the medical records of all patients in whom GDC embolization for the treatment of intracranial aneurysms was undertaken between February 1, 1990 and October 31, 1999. Clinical presentation, medical comorbidities, anesthetic agents used, intraprocedural complications, and final procedural outcome were recorded for each patient. Guglielmi detachable coil embolization was attempted in the awake patient in 150 procedures. Among 92 procedures for unruptured aneurysms, 75 (82%) were completed without complications. Four procedures were completed with complications. Of the 92 procedures, 13 were aborted due to patient uncooperativeness (one patient), complications (three patients), morphological characteristics of the aneurysm or surrounding vessels that made embolization technically difficult (eight patients), or vasospasm (one patient). Among 58 procedures for ruptured aneurysms, the procedure was completed without complication in 48 cases (83%). The procedure was completed with complications in five cases and two patients required induction of general anesthesia during the procedure. Five procedures were aborted because morphological characteristics of the aneurysm or surrounding vessels made embolization technically difficult (two patients) or because of aneurysm rupture (two patients) or the appearance of a transient neurological deficit (one patient)., Conclusions: Embolization of intracranial aneurysms performed using GDCs in the awake patient appears to be safe and feasible and allows intraprocedural evaluation of the patient. Potential advantages, including decreased cardiopulmonary morbidity rates, shorter hospital stay, and lower hospital costs, still require confirmation by a direct comparison with other anesthetic procedures.

Object: Results of previous in vitro and in vivo experimental studies have suggested that placement of a porous stent within the parent artery across the aneurysm neck may hemodynamically uncouple the aneurysm from the parent vessel, leading to thrombosis of the aneurysm. For complex wide-necked aneurysms, a stent may also aid packing of the aneurysm with Guglielmi detachable coils (GDCs) by acting as a rigid scaffold that prevents coil herniation into the parent vessel. Recently, improved stent system delivery technology has allowed access to the tortuous vascular segments of the intracranial system. The authors report here on the use of intracranial stents to treat aneurysms involving different segments of the internal carotid artery (ICA), the vertebral artery (VA), and the basilar artery (BA)., Methods: Ten patients with intracranial aneurysms located at ICA segments (one petrous, two cavernous, and three paraclinoid aneurysms), the VA proximal to the posterior inferior cerebellar artery origin (one aneurysm), or the BA trunk (three aneurysms) were treated since January 1998. In eight patients, stent placement across the aneurysm neck was followed (immediately in four patients and at a separate procedure in the remaining four) by coil placement in the aneurysm, accomplished via a microcatheter through the stent mesh. In two patients, wide-necked aneurysms (one partially thrombosed BA trunk aneurysm and one paraclinoid segment aneurysm) were treated solely by stent placement; coil placement may follow later if necessary. No permanent periprocedural complications occurred and, at follow-up examination, no patient was found to have suffered symptoms referable to aneurysm growth or thromboembolic complications. Greater than 90% aneurysm occlusion was achieved in the eight patients treated by stent and coil placement as demonstrated on immediate postprocedural angiograms. Follow-up angiographic studies performed in six patients at least 3 months later (range 3-14 months) revealed only one incident of in-stent stenosis. In the four patients originally treated solely by stent placement, no evidence of aneurysm thrombosis was observed either immediately postprocedure or on follow-up angiographic studies performed 24 hours (two patients), 48 hours, and 3 months later, respectively., Conclusions: A new generation of flexible stents can be used to treat complex aneurysms in difficult-to-access areas such as the proximal intracranial segments of the ICA, the VA, or the BA trunk. The stent allows tight coil packing even in the presence of a wide-necked, irregularly shaped aneurysm and may provide an endoluminal matrix for endothelial growth. Although convincing experimental evidence suggests that stent placement across the aneurysm neck may by itself promote intraluminal thrombosis, the role of this phenomenon in clinical practice may be limited at present by the high porosity of currently available stents.

Object: The authors conducted a retrospective study to evaluate the treatment of complex C1-2 fractures., Methods: There were 10 cases of complex C1-2 fractures. Six patients were men (median age 58 years) and four patients were women (median age 55.5 years). Injuries resulted from seven falls, two motor vehicle accidents, and one diving incident. Three patients suffered from upper-extremity weakness. Neurological function in seven patients was intact preoperatively. Fracture combinations included six Jefferson/Type II odontoid, two anterior ring/Type II odontoid, one posterior ring/Type II odontoid, and one posterior ring/Type III odontoid/Type III hangman's fracture. All patients underwent surgery, five after halo immobilization for an average of 4 months failed to provide stability. Treatment included placement of six odontoid screws, one posterior C1-2 transarticular screw, one odontoid screw with anterior C1-2 transarticular screw fixation, one C1-2 transarticular screw with C1-2 Songer cable fusion, and one odontoid screw with bilateral C-2 pedicle screw fixation. Specific treatment was determined by the combination of fractures. Postoperatively, all patients were immobilized in a hard collar for 3 months. There were no intraoperative surgery-related complications. The mean follow-up period was 28.5 months. Neurological recovery was observed in one of three patients who presented with neurological deficits. Fusion occurred in all cases., Conclusions: The goals in treating these complex fractures are to achieve early maximum stability and minimum reduction in range of motion. These are often competing phenomena. Frequently in cases of atlas-axis fracture, odontoid screw fixation combined with hard collar immobilization is the best therapy, provided the transverse atlantal ligament is competent. If not, C1-2 stabilization with placement of transarticular screws is required for best results.

Primary reconstruction using bone grafts and instrumentation for spinal infections remains controversial. Between 1991 and 1993, 27 infections of the spinal column were treated at the Department of Neurosurgery of the University of Florida. Of the 27 cases 20 (six cervical, eight thoracic, and six lumbar spine) required surgical debridement and spinal reconstruction to maximize eradication of the infection and maintenance of spinal alignment. All of the cervical and lumbar cases were caused by bacterial infections, and two of eight thoracic cases were caused by tuberculous infections. Spinal arthrodesis was performed in all cases: interbody grafts were used in 18 procedures and posterolateral onlay grafts in 14. Interbody grafts were autologous in 10 cases (six rib and four iliac crest) and allograft in eight (six fibular and two humerus). All of the posterolateral onlay grafts were autologous (three rib and 11 iliac crest). Spinal instrumentation was used in 15 cases: four with Caspar plates and 11 with posterior segmental fixation (five hook/rod constructs and six screw/rod constructs). Seventeen of 20 patients achieved improved clinical status postoperatively and 18 of 20 showed radiographic evidence of bone fusion. Antibiotic drugs were administered parenterally for an average of 6 weeks followed by a 3-month course of oral antibiotic medications. Tuberculous infections were treated for 1 year with antibiotic therapy. The average follow-up period was 37 months from surgery and 31 months after completion of treatment with antibiotic drugs. The authors conclude that primary arthrodesis and instrumentation can be performed in acute spinal infections; however, successful management depends on aggressive debridement of infectious foci and prolonged treatment with parenteral antibiotic drugs.

Six ventrally located intradural thoracic tumors were successfully resected through the posterolateral approach. This approach allows direct visualization of the ventral and dorsal boundaries of the tumor with minimal manipulation of the spinal cord. Compared to the traditional laminectomy, the operative time is increased but visualization of the tumor and spinal cord is markedly improved. Compared to the transthoracic approach, the posterolateral approach has fewer potential complications and eliminates the necessity of vertebrectomy. Neurological improvement occurred in all six patients. It is believed that this approach offers significant advantages for the treatment of ventrally located intradural thoracic tumors, and should be considered an alternative to the transthoracic approach.

The introduction of microdiscectomy to lumbar spine surgery has resulted in a significant decrease in postoperative pain and length of hospital stay. Intraoperative application of long-acting local anesthetic agents has been used for many general and neurosurgical procedures for the management of postoperative pain. In addition, many surgeons routinely use intraoperative corticosteroids during lumbar discectomy to reduce traumatic nerve root inflammation. However, the efficacy of intraoperative long-acting local anesthetic agents and corticosteroids for reduction of postoperative discomfort has not been reported for lumbar discectomy. This study evaluated 32 patients at a university-based Veterans Administration hospital undergoing lumbar microdiscectomy. All 32 patients presented with radicular symptoms and had radiographic confirmation of a herniated nucleus pulposus. These patients were divided into three groups. Group 1 (12 patients) received 160 mg intramuscular Depo-Medrol (methylprednisolone acetate) and 250 mg intravenous Solu-Medrol (methyl-prednisolone sodium succinate) at the start of the operation. A macerated fat graft soaked in 80 mg Depo-Medrol was placed over the affected nerve root following discectomy. In addition, 30 ml of 0.25% bupivacaine was infiltrated into the paraspinal musculature at skin incision and during closure. Group 2 (10 patients) received 30 ml of 0.25% bupivacaine infiltrated into the paraspinal musculature at skin incision and at closure. In this group of patients, a saline-soaked fat graft was placed over the affected nerve root. Group 3 (10 patients) acted as a control group, undergoing lumbar microdiscectomy without corticosteroids or bupivacaine. Patients receiving bupivacaine and corticosteroids (Group 1) had a statistically significantly shorter hospital stay (1.4 days) compared to the control group (4.0 days) (p = 0.0004, Mann-Whitney U-test). Patients in Group 1 required less postoperative narcotic analgesia than the other groups. Finally, a larger percentage of patients in Group 1 reported complete relief of back and radicular pain on postoperative Day 1 compared to other groups. Postoperative complications and functional outcome were not different between the groups. These results indicate that the combination of long-acting anesthetic agents and corticosteroids can reduce postoperative discomfort and subsequently the length of postoperative hospital stay.

A total of 104 patients underwent transpedicular spinal instrumentation using the Cotrel-Dubousset (71 cases) or the Texas Scottish Rite Hospital (33) screw-rod system. Surgery was performed for lumbar vertebral column instability secondary to fractures (28 cases), spondylolisthesis (29), tumors (four), vertebral osteomyelitis (two), or postoperative causes (41). Pseudoarthrodesis due to failure of a prior fusion was present in 37 cases. The 55 men and 49 women (mean age 47 years, range 18 to 87 years) all presented with severe back pain. Signs or symptoms of neural compression were noted in 96 patients. Surgery consisted of neural decompression, internal fixation, and autogenous iliac bone grafting. Spondylolistheses were fused in situ, without reduction; otherwise, major spinal deformities were corrected. A total of 516 pedicle screws were placed. The mean extent of fusion was 2.7 motion segments (range one to six motion segments). A 96% fusion rate was obtained with a mean follow-up period of 20 months. There were no operative deaths. Major complications included one spinal epidural hematoma, three isolated nerve root deficits (two transient, one permanent), and three wound infections (two deep, one superficial). Instrument failure eventually developed in 18 patients; nine were asymptomatic with a solid fusion and did not require further treatment and the other nine were symptomatic or had a pseudoarthrosis and required operative revision. Pedicle screw-rod fixation offers biomechanical advantages compared to other forms of internal fixation for the lumbar spine. It enables short-segment fixation with preservation of lumbar lordosis and adjacent normal motion segments. This technique provides a highly successful method to obtain arthrodesis, even with prior pseudoarthrosis.

Twenty-seven cases of craniovertebral junction compression treated with transoral surgery were reviewed to assess the influences of pathological processes and surgical interventions on spinal stability. All patients presented with signs and symptoms of spinal-cord or brain-stem dysfunction. Pathology included rheumatoid arthritis in 11 patients, congenital osseous malformations in 11, spinal fractures in two, plasmacytoma in one, osteomyelitis in one, and a gunshot injury in one. Instability was defined as clear radiographic evidence of mobile subluxation in conjunction with clinical assessment. Of 19 patients (70%) requiring internal fixation, nine underwent upper cervical fusion and 10 had occipitocervical fusion. When instability occurred, all subluxations were at the C1-2 level. There were no occipito-atlantal subluxations. Eight patients (30%) had preoperative instability of the craniovertebral junction due solely to their pathology, 11 patients (40%) suffered instability after transoral surgery, and eight (30%) were without clinical or radiographic evidence of instability (mean follow-up period 14 months). Craniovertebral junction instability predominated among patients with rheumatoid arthritis: 91% required fusion and 45% presented with pre-existing instability. Among individuals with congenital osseous malformations, 45% required fusion and only one patient (9%) had pre-existing instability. Patients who required subsequent posterior decompression of a Chiari malformation were at risk for developing instability; three of four became unstable after posterior decompression. Transoral resection of the dens, the anterior arch of C-1, and the lower clivus does not fully destabilize the spine; however, this operation may potentiate incipient pathological instability. The primary determinants of instability are the extent of pathological bone destruction, ligamentous weakening, and operative bone removal. Long-term follow-up monitoring is needed after transoral surgery to detect cases of late instability.

The upper thoracic vertebrae are difficult to approach surgically because of the narrowing of the thoracic inlet, the proximity of the brachial plexus, and the parascapular shoulder musculature. A novel lateral parascapular extrapleural approach to the upper thoracic vertebrae is described. The parascapular shoulder musculature (trapezius, levator scapulae, and rhomboid muscles) is reflected off the spinous processes to the scapula as a musculocutaneous flap, preserving the neurovascular supply. The paraspinal musculature is mobilized and retracted, and the upper dorsal ribs are removed with caution to avoid injury to the C-8 and T-1 nerve roots. The rami communicantes are transected, and the sympathetic chain is displaced anterolaterally. The T2-4 vertebrae can be approached unobstructed. The T-1 nerve root obstructs posterolateral access to the T-1 vertebra, necessitating an inferolateral approach underneath the T-1 nerve root axilla. Four patients with compressive myelopathy from upper thoracic vertebral metastases underwent neural decompression, vertebral reconstruction, and posterior spinal fixation with this approach. Their postoperative neurological status was either unchanged or improved. Complications included radiographic pleural effusion and superficial wound dehiscence; one patient required posterior spinal reinstrumentation for progressive kyphosis. One patient developed pneumonia 7 days postoperatively which was unresponsive to appropriate treatment. It is believed that the anatomical limitations to this region have been overcome, and that excellent exposure of the T1-4 vertebrae for neural decompression and vertebral reconstruction can be performed safely. A major advantage is that posterior spinal fixation can be carried out simultaneously.

Much interest has recently been focused on the possible role of the endogenous opiates in the perception of pain in humans. Several investigators have examined the levels of these substances in human cerebrospinal fluid (CSF) in attempts to identify the mechanisms by which electrical stimulation of the brain might induce analgesia. Most of these CSF samples were collected at the time of ventriculography or myelography. In the present study, the levels of beta-endorphin in the CSF of 22 patients undergoing myelography were examined before and after the injection of a contrast agent. beta-Endorphin increased an average of 356% (p less than 0.0005) 15 to 20 minutes following the injection of contrast material into the lumbar subarachnoid space. Thus, routine myelography may have a profound effect on the levels of beta-endorphin measured by radioimmunoassay in human CSF, and great care must be taken in interpreting the significance of changes seen in beta-endorphin levels in CSF collected from patients at the time of myelography or ventriculography. The effect of the injection of contrast material on beta-endorphin immunoreactivity must be distinguished from the postulated effects of any analgesia-inducing therapy.

The risk of hemorrhagic complications with anticoagulation therapy in patients following intracranial surgery has prevented investigation of the potential use of heparin in the early postoperative period. The authors have evaluated the safety of anticoagulation therapy following experimental craniotomy in male Holtzman rats. The dose and schedule of heparin administration, which elevated and maintained the activated partial thromboplastin time (APTT) within the therapeutic range of 1 1/2 to 3 X control APTT, was alternating doses of 400 and 500 IU/kg injected subcutaneously every 6 hours. This schedule was initiated 2, 4, 7, 10, and 14 days after craniotomy and was continued for 72 hours thereafter. The results demonstrated that the incidence of intracerebral hemorrhage declined as the postoperative interval prior to initiation of anticoagulation increased. If anticoagulation therapy was initiated during the first 7 postoperative days, the risk of intracerebral hemorrhage was high (mean 14.7%): however, if an additional 3 to 7 days elapsed prior to initiation of anticoagulation, the incidence of intracerebral hemorrhage dropped significantly (mean 0%) (p less than 0.05). These results suggest that anticoagulation therapy can be safely initiated 10 to 14 days after craniotomy.

Six adult dogs were implanted stereotaxically with chronic indwelling Medtronic platinum-tipped electrodes in the left ventromedial hypothalamic area (VMH); two dogs with electrodes placed in the subcortical white matter served as controls. Following 24 hours of food deprivation, VMH-stimulated dogs delayed their next meal for a period ranging from 1 to 18 hours. When not stimulated, however, each dog ate immediately upon receiving its food and consumed greater than average daily intake (p less than 0.005). The two control dogs ate immediately upon receiving food regardless of whether they were stimulated or not. Dogs that received 1 hour of VMH stimulation every 12 hours for 3 consecutive days maintained an average daily food intake of 35% of normal baseline levels (range 13% to 51%), and water consumption averaged 50% of baseline intake (range 29% to 67%). Both of these results were statistically significant (p less than 0.01). After cessation of stimulation, food and water intake returned to normal within 6 to 9 days, with no observable "rebound hyperphagia." The two animals that received subcortical electrodes showed no change in food or water intake with stimulation. Blood pressure, pulse, respiration, temperature, and gross behavior were not altered during or after stimulation. These results suggest that the use of electrical stimulation of the VMH may be a useful modality for regulating food intake, and deserves further examination as a potential alternative therapy for human morbid obesity.