Search

Objective: The objective of this study was to identify factors that lead to a prolonged hospital stay or 30-day readmission after minimally invasive surgery (MIS) for transforaminal lumbar interbody fusion (TLIF) at a single institution., Methods: Consecutive patients who underwent MIS TLIF from January 1, 2016, to March 31, 2018, were retrospectively analyzed. Demographic data, including age, sex, ethnicity, smoking status, and body mass index, were collected along with operative details, indications, affected spinal levels, estimated blood loss, and operative duration. The effects of these data were evaluated relative to the hospital length of stay (LOS) and 30-day readmission., Results: The authors identified 174 consecutive patients who underwent MIS TLIF at 1 or 2 levels from a prospectively collected database. The mean (range) patient age was 64.1 (31-81) years, 97 were women (56%), and 77 were men (44%). Of 182 levels fused, 127 were done at L4-5 (70%), 32 at L3-4 (18%), 13 at L5-S1 (7%), and 10 at L2-3 (5%). Patients underwent 166 (95%) single-level procedures and 8 (5%) 2-level procedures. The mean (range) procedural duration, defined as the time from incision to closure, was 164.6 (90-529) minutes. The mean (range) LOS was 1.8 (0-8) days. Eleven patients (6%) were readmitted within 30 days; the most frequent causes were urinary retention, constipation, and persistent or contralateral symptoms. Seventeen patients had LOS greater than 3 days. Six of those patients (35%) were identified as widows, widowers, or divorced, and 5 of them lived alone. Six patients with prolonged LOS (35%) required placement in either skilled nursing or acute inpatient rehabilitation. Regression analyses showed living alone (p = 0.04) and diabetes (p = 0.04) as predictors of readmission. Regression analyses revealed female sex (p = 0.03), diabetes (p = 0.03), and multilevel surgery (p = 0.006) as predictors of LOS > 3 days., Conclusions: Urinary retention, constipation, and persistent radicular symptoms were the leading causes of readmission within 30 days of surgery in this series, which is distinct from data from the American College of Surgeons National Surgical Quality Improvement Program. The inability to discharge a patient home for social reasons led to prolonged inpatient hospital stays. Identifying these risk factors and proactively addressing them could lower readmission rates and decrease LOS among patients undergoing MIS TLIF.

Objective: Since the first resections of intradural extramedullary neoplasms, neurosurgeons have tended to preserve as much of the integrity of the spine as possible while ensuring a safe corridor to resect these lesions. A dimensional analysis of intradural lesions superimposed on a dimensional analysis of the thoracic canal would provide the anatomic basis for a minimal access approach. The authors report the results of such an analysis on a series of patients with intradural extramedullary lesions., Methods: A retrospective analysis was undertaken of 26 thoracic intradural extramedullary lesions managed with open or minimally invasive resection. The size of each lesion was measured in the rostrocaudal, lateral, and anteroposterior dimensions and then averaged and compared with reported dimensions of the thoracic spinal canal., Results: The mean (range) dimensions of the surgically resected thoracic lesions were 18.6 mm (10-25 mm) for rostrocaudal, 13.0 mm (7-18 mm) for lateral, and 13.6 mm (9-17 mm) for anteroposterior. No patient had any evidence of thoracic canal remodeling., Conclusions: Thoracic intradural extramedullary lesions become symptomatic as they approach the limits of the thoracic canal, resulting in an inherent dimensional limitation in the rostrocaudal, lateral, and anteroposterior dimensions. Displacement of the spinal cord by the lesion to one side further favors a minimally invasive unilateral approach. A paraspinal unilateral hemilaminectomy approach with a 35 × 20 mm exposure centered over the lesion offers a safe surgical corridor for resection while preserving the posterior tension band, facet complexes, and paraspinal musculature., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Recent research on radiation exposure in minimally invasive surgery for transforaminal lumbar interbody fusion (MIS TLIF) has led to the development of a low-dose radiation fluoroscopy protocol, with resulting reductions in fluoroscopy times and radiation exposures., Objective: To prospectively evaluate a previously reported low-dose radiation fluoroscopy protocol for MIS TLIF., Methods: A prospective evaluation of the low-dose radiation fluoroscopy protocol for MIS TLIF was performed for 65 consecutive patients. Total fluoroscopy time, radiation dose, and operative times were prospectively analyzed for all enrolled patients., Results: Sixty-five consecutive patients (43 women; 22 men) who underwent an MIS TLIF were prospectively enrolled in this study of the low-dose fluoroscopy protocol. A total of 260 pedicle screws were placed. The mean age of the patients was 63 years (range, 46-82 years). They had a mean operative time of 178.7 minutes (range, 119-247 minutes), a mean fluoroscopic time of 10.43 seconds (range, 5-24 seconds), and a mean radiation dose of 0.295 mGy × m2 (range, 0.092-0.314 mGy × m2)., Conclusion: The combination of low-dose pulsed images and digital spot images in a low-dose protocol decreases fluoroscopy times and radiation doses in patients undergoing MIS TLIF without compromising visualization of the bony anatomy or the safety and efficiency of the procedure. The application of this low-dose protocol uncouples the otherwise linear relationship between fluoroscopy times and radiation dose. This is due primarily to the use of the digital spot technique. Equal emphasis should be placed on radiation dose and acquisition time to optimize this protocol.

Background: Lumbar disc degeneration may be so advanced and asymmetrical that transforaminal access to the interbody space is limited. The extent of collapse may compromise the capacity to restore disc height and coronal balance in minimally invasive approaches. Although a variety of distractors are available for open approaches, currently there is no feasible distractor that is functional within a minimally invasive retractor., Objective: To describe the development of a provisional ipsilateral expandable rod for use in minimally invasive surgery for transforaminal lumbar interbody fusions to optimize access to the disc space, thereby facilitating placement of an interbody spacer., Methods: The authors report the clinical and radiographic data for 30 patients (3 open and 27 minimally invasive surgeries) with advanced degenerative disc disease in whom a provisional ipsilateral expandable rod was used to restore coronal balance and maintain disc height for interbody preparation and placement. Preoperative disc heights were measured, and the height of interbody spacer recorded. Mean restoration of disc heights was calculated., Results: The provisional ipsilateral expandable rod was successfully applied in both open exposures and within a minimally invasive retractor. The mean preoperative disc height was 4.9 mm (range, 1-9 mm), the mean height of the spacer inserted was 11.1 mm (range, 8-15 mm), and the mean increase in disc height was 6.2 mm (range, 5-11 mm)., Conclusion: A provisional ipsilateral expandable rod is feasible in either minimally invasive or open approaches. It has the capacity to maintain the disc height achieved by paddle distractors. This facilitates both the disc preparation and optimizes restoration of disc height and interbody spacer placement.

Object: There is an increasing awareness of radiation exposure to surgeons and the lifelong implications of such exposure. One of the main criticisms of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is the amount of ionizing radiation required to perform the procedure. The goal in this study was to develop a protocol that would minimize the fluoroscopy time and radiation exposure needed to perform an MIS TLIF without compromising visualization of the anatomy or efficiency of the procedure., Methods: A retrospective review of a prospectively collected database was performed to review the development of a low-dose protocol for MIS TLIFs in which a combination of low-dose pulsed fluoroscopy and digital spot images was used. Total fluoroscopy time and radiation dose were reviewed for 50 patients who underwent single-level MIS TLIFs., Results: Fifty patients underwent single-level MIS TLIFs, resulting in the placement of 200 pedicle screws and 57 interbody spacers. There were 28 women and 22 men with an average age of 58.3 years (range 32-78 years). The mean body mass index was 26.2 kg/m(2) (range 17.1-37.6 kg/m(2)). Indications for surgery included spondylolisthesis (32 patients), degenerative disc disease with radiculopathy (12 patients), and recurrent disc herniation (6 patients). Operative levels included 7 at L3-4, 40 at L4-5, and 3 at L5-S1. The mean operative time was 177 minutes (range 139-241 minutes). The mean fluoroscopic time was 18.72 seconds (range 7-29 seconds). The mean radiation dose was 0.247 mGy*m(2) (range 0.06046-0.84054 mGy*m(2)). No revision surgery was required for any of the patients in this series., Conclusions: Altering the fluoroscopic technique to low-dose pulse images or digital spot images can dramatically decrease fluoroscopy times and radiation doses in patients undergoing MIS TLIFs, without compromising image quality, accuracy of pedicle screw placement, or efficiency of the procedure.

Background: After intradural cranial surgery, a dural substitute is often required for dural closure. Although preferred, limitations of autograft include local availability and additional surgical site morbidity. Thus, allografts, xenografts, and synthetics are frequently used., Objective: To report 6-month results of a randomized, controlled trial of a biosynthesized cellulose (BSC) composed duraplasty device compared with commercially available dural replacements., Methods: A total of 99 patients (62 BSC; 37 control) were treated on protocol, using a 2:1 (BSC:control) blocked randomization schedule. Physical examinations were performed pre- and postoperatively within 10 days and at 1, 3, and 6 months. Magnetic resonance imaging was performed preoperatively and at 6 months. The primary study endpoint was the absence of pseudomeningocele and extracerebral fluid collection confirmed radiographically and the absence of cerebrospinal fluid fistula at 6 months., Results: At 6 months, the primary hypothesis, noninferiority of the BSC implant compared with the control group, was confirmed (P = .0206). Overall success was achieved by 96.6% of BSC and 97.1% of control patients. No significant difference was revealed between treatment groups for surgical site infection (P = 1.0000) or wound healing assessment (P ≥ .3685) outcomes, or radiologic endpoints (P ≥ .4061). Device strength and seal quality favored BSC., Conclusion: This randomized, controlled trial establishes BSC as noninferior to commercially available dural replacement devices. BSC offers a hypothetical advantage concerning prion and other infectious agent exposure; superior handling qualities are evident. Longer term data are necessary to identify limitations of BSC and its potential equivalence to the gold standard of pericranium.

Background Context: Most one-level anterior cervical plates use two screws per vertebra (four screws in total). No study has addressed whether a simplified plate using one screw per vertebra is adequate for one-level fixation., Purpose: To compare stability achieved by four-screw and two-screw plates after discectomy and placement of interbody spacer., Study Design: Nondestructive multidirectional flexibility tests were performed in three independent groups of cadaveric spines to assess spinal stability after instrumentation., Methods: Human cadaveric C4-C7 specimens were tested intact and after discectomy followed by placement of a polyetheretherketone interbody graft and an anterior plate. Rigid two-screw (n=8), semiconstrained four-screw (n=8), and rigid four-screw (n=8) plates were compared. Nonconstraining pure moments were applied under load control (maximum 1.5 Nm) to induce flexion, extension, lateral bending, and axial rotation, whereas vertebral motion was measured optoelectronically. Mean range of motion (ROM) was compared among groups., Results: All three plates significantly reduced ROM relative to normal in all directions of loading (p<.003). Mean ROMs±standard deviation (and corresponding intergroup p value) for rigid two-screw, semiconstrained four-screw, and rigid four-screw plates, respectively, were as follows: flexion: 2.6±2.0°, 1.8±1.1°, 1.8±0.8° (p=.46); extension: 2.5±2.6°, 2.1±1.3°, 1.4±1.3° (p=.45); lateral bending: 1.8±1.0°, 1.3±1.0°, 1.1±0.5° (p=.29); axial rotation: 2.9±1.9°, 1.6±0.9°, 1.5±0.7° (p=.08). Despite a tendency for the rigid two-screw plate to allow more motion than the four-screw plates, there was no significant difference among groups during any loading mode., Conclusions: In terms of immediate postoperative cervical stability after one-level discectomy and placement of an interbody spacer, the rigid two-screw plate performed comparably to conventional rigid four-screw and semiconstrained four-screw plates. Further research on relative fatigue endurance of the different plate types is also needed., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Objective: A standard top-loading lumbar pedicle screw-rod system is compared with a pedicle screw-plate system with smaller-diameter screws, more medial entry, and lower profile to assess the relative stability, strength, and resistance to fatigue of the 2 systems., Methods: Seven human cadaveric specimens were studied with each surgical construct. Nondestructive, nonconstraining pure moments were applied to specimens to induce flexion, extension, lateral bending, and axial rotation while recording L5-S1 motion optoelectronically. After initial tests, specimens were fatigued for 10,000 cycles and retested to assess early postoperative loosening. Specimens were then loaded to failure in hyperextension., Results: The standard screw-rod construct reduced range of motion to a mean of 20% of normal, whereas the screw-plate construct reduced range of motion to 13% of normal. Differences between systems were not significant in any loading mode (P > 0.06). The 14% loosening of the screw-rod system with fatigue was not significantly different from the 10% loosening observed with the screw-plate system (P > 0.15). Mean failure loads of 30 Nm for screw-rod and 37 Nm for screw-plate were also not significantly different (P = 0.38)., Conclusion: Posterior fixation at L5-S1 using the low-profile screw-plate system offers stability, resistance to fatigue, and resistance to failure equivalent to fixation using a standard cantilevered pedicle screw-rod system.

Object: An experiment was performed to study the limits of the ability of screws designed to center themselves in the pedicle during insertion, and to study whether straight-ahead versus inward screw insertion trajectories differ in their resistance to pullout., Methods: Forty-nine human cadaveric lumbar vertebrae were studied. Pedicle screws were inserted in trajectories starting 0 degrees, 10 degrees, 20 degrees, or 30 degrees from the optimal trajectory, either medially or laterally misdirected. The surgeon then inserted the screw with forward thrust but without resisting the screw's tendency to reorient its own trajectory during insertion. On the opposite pedicle, a control screw was inserted with the more standard inward-angled anatomical trajectory and insertion point. Cortical wall violation during insertion was recorded. Screws were then pulled out at a constant displacement rate while ultimate strength was recorded., Results: Lateral misdirection as small as 10 degrees was likely to lead to cortical wall violation (3 of 7 violations). Conversely, medial misdirection usually resulted in safe screw insertion (1 of 21 violations for 10 degrees, 20 degrees, or 30 degrees medial misdirection). The resistance to pullout of screws inserted in a straight-ahead trajectory did not differ significantly from that of screws inserted along an inward trajectory (p = 0.68)., Conclusions: Self-tapping, self-drilling pedicle screws can redirect themselves to a much greater extent during medial than during lateral misdirection. The cortical wall is more likely to be violated laterally than medially. The strength of straight-ahead and inward trajectories was equivalent.

Study Design: A new anchored spacer-a low-profile cervical interbody fusion cage with integrated anterior fixation-was compared biomechanically to established anterior cervical devices., Objective: To evaluate the fixation properties of the new stand-alone device and compare these properties with established fixation methods. The hypothesis is that the new device will provide stability comparable to that provided by an anterior cervical cage when supplemented with an anterior plate., Summary of Background Data: It is accepted that the use of anterior cervical plating increases the chance of achieving a solid fusion. However, its use may be associated with an increase in operation time and a higher postoperative morbidity caused by a larger anterior approach and disruption of the anterior musculature. This dilemma has led to the development of a new, low profile stand-alone cervical anterior cage device with integrated screw fixation., Methods: Twenty-four human cadaveric C4-C7 cervical spines were loaded nondestructively with pure moments in a nonconstraining testing apparatus to induce flexion, extension, lateral bending, and axial rotation while angular motion was measured optoelectronically. The specimens were tested: 1. Intact (N = 24). 2. After discectomy and anterior stabilization. a. Interbody cage + locking plate (N = 8). b. Interbody cage + dynamic plate (N = 8). c. Anchored spacer (N = 8). 3. After ventral plate removal of group 2a and 2b (N = 16)., Results: All fixation techniques decreased range of motion (ROM) and lax zone (LZ) (P < 0.05) in all test modes compared with the intact motion segment and cage-only group. There were no significant differences between the anchored spacer and cage + locking plate or cage + dynamic plate., Conclusion: The anchored spacer provided a similar biomechanical stability to that of the established anterior fusion technique using an anterior plate plus cage and has a potentially lower perioperative and postoperative morbidity. These results support progression to clinical trials using the cervical anchored spacer as a stand-alone implant.

A new theoretical framework is used to analyze functions and pathophysiological processes of cortico-basal ganglia-thalamocortical loops and to demonstrate the hierarchical relationships between various loops. All hierarchical levels are built according to the same functional principle: Each loop is a neural optimal control system (NOCS) and includes a model of object behavior and an error distribution system. The latter includes dopaminergic neurons and is necessary to tune the model to a controlled object (CO). The regularities of pathophysiological processes in NOCSs are analyzed. Mechanisms of current functional neurosurgical procedures like lesioning and deep brain stimulation (DBS) of various basal ganglia structures and neurotransplantation are described based on proposed theoretical ideas. Parkinson's disease (PD) is used to exemplify clinical applications of the proposed theory. Within the proposed theoretical framework, PD must be considered as a disease of the error distribution system. The proposed theoretical views have broad fundamental and clinical applications.

Objective: Lesions situated posterolaterally along the mesencephalon present neurosurgeons with a special challenge. The midline and paramedian variations of the supracerebellar infratentorial approaches do not adequately expose this region. The subtemporal approach risks injury to the vein of Labbé. An extreme lateral supracerebellar infratentorial approach with more radical resection of bone superiorly and laterally, and skeletonization of the sigmoid and transverse sinuses, was used to approach lesions at this location in eight, Methods: Five cavernous malformations, two juvenile pilocytic astrocytomas, and one peripheral superior cerebellar artery aneurysm located in this region were approached in eight patients. In this extreme lateral approach, the sigmoid sinus is unroofed more superiorly and the bone flap includes not only a posterior fossa craniotomy but also a portion that extends just above the transverse sinus. The dural opening is based along the transverse and sigmoid sinuses. After the cerebrospinal fluid has been drained, the lateral aspect of the brainstem is approached via the cerebellar surface. A proximal tentorial incision offers additional rostral exposure where needed., Results: Seven patients in this series underwent successful resection of their lesion. The remaining patient's aneurysm was clipped successfully with no major complications., Conclusion: The extreme lateral supracerebellar infratentorial approach differs from the midline and paramedian supracerebellar infratentorial variants in the area of exposure, patient positioning, and location of the craniotomy. The technique is effective for approaching the posterolateral mesencephalon.

Introduction: Surgical management of traumatic internal carotid artery (ICA) dissection remains controversial. Therefore, the delayed outcomes and graft patency rates of patients who underwent bypass procedures for symptomatic traumatic ICA dissection were studied., Methods: Between September 1989 and August 1996, 13 patients (9 male and 4 female patients; mean age, 30.6 yr) underwent 16 revascularization procedures for symptomatic traumatic ICA dissection. The duration of clinical follow-up averaged 47.3 months (range, 12-94 mo) from the date of diagnosis. The duration of radiographic follow-up (catheter or magnetic resonance angiography, duplex Doppler ultrasonography) averaged 24 months (range, 12-60 mo)., Results: ICA dissection was caused by blunt (n = 11) or penetrating trauma (n = 2). Associated angiographic abnormalities included seven ipsilateral ICA occlusions, six dissecting aneurysms, two carotid-cavernous fistulae, and six contralateral traumatic ICA dissections. Patients requiring early revascularization (n = 6) underwent bypass procedures an average of 19.2 days after their injuries. Medically managed patients who developed ischemia later were revascularized a mean of 7.8 months after injury. The mean Glasgow Coma Scale score at the time of presentation was 10 (range, scores of 6-15), and the mean Glasgow Coma Scale score before revascularization was 14 (range, scores of 9-15). There were 14 saphenous vein ICA bypasses (8 cervical-to-petrous, 3 cervical-to-middle cerebral artery, 3 petrous-to-supraclinoid) and 2 superficial temporal artery-to-middle cerebral artery bypasses. There was one early postoperative graft occlusion, which responded to surgical thrombectomy. One patient with multiple other traumatic injuries died as a result of a pulmonary embolus 12 months after revascularization. All remaining patients had Glasgow Outcome Scale scores of 5, with patent bypass grafts confirmed during follow-up., Conclusion: Revascularization for persistently symptomatic traumatic ICA dissection eliminated ischemia and was associated with excellent long-term outcomes and graft patency rates.

The authors report a rare case of a hangman's fracture involving complete dislocation of C-2 onto C-3, accompanied by a C2-3 locked facet and asymptomatic bilateral vertebral artery injuries. The patient, a 25-year-old man who sustained a neck injury in an industrial accident, presented with a mild central spinal cord syndrome. His initial lateral cervical radiograph showed complete anterior dislocation of the C-2 body onto C-3, bilateral neural arch fractures, and a unilateral locked facet. The mechanism was likely flexion and compression. The grossly unstable spine and the locked facet were treated by posterior decompression, reduction, and C1-3 fixation. The patient recovered in several days and is without neurological deficit.

Although the efficacy of posterior decompression for symptomatic lumbar stenosis that is recalcitrant to conservative therapy is well proven, uniform agreement on the need for simultaneous arthrodesis is lacking. The variability in the rate of lumbar fusion with and without instrumentation has been attributed to a number of factors: advances in surgical technique; rapid development of instrumentation; radiographic advances in the diagnosis of disease entities of the lumbar spine; evolution in our understanding of bone healing; improved pre- and postoperative care; aggressive rehabilitation; patient compensation; hospital and surgeon reimbursement; better education of residents, fellows, and practicing neurosurgeons; and, most important, the lack of clear indications based on defined diagnostic categories. Based on review of the literature and their experience at the Barrow Neurological Institute, the authors have attempted to define indications for lumbar fusion with or without instrumentation based on defined diagnostic categories. Clear indications for fusion include trauma, tumor, or infection with two- or three-column injury, iatrogenic instability, and isthmic spondylolisthesis. Relative indications for fusion include degenerative spondylolisthesis, radiographically proven dynamic instability with pain or neurological findings, adult scoliosis, and mechanical back pain. Fusion is rarely indicated with discectomy, abnormal radiographs without appropriate findings (such as degenerative disc disease), facet joint syndrome, failed back surgery, or stable spinal stenosis.

Patients with a nonpenetrating head injury and traumatic subarachnoid hemorrhage (tSAH) on admission head computed tomography scan (n = 240) were compared with patients without tSAH matched in terms of admission postresuscitation Glasgow Coma Scale (GCS) values, age, sex, and the presence of one or more types of intracranial mass lesions. Admission Injury Severity Score was higher only in tSAH patients with admission GCS scores between 13 and 15; GCS values at 6, 24, and 48 hours were lower for tSAH patients. Patients with tSAH underwent fewer craniotomies, but more than twice as many tSAH patients had high intracranial pressure at the time of ventriculostomy placement and 6 hours after admission. tSAH patients underwent more chest procedures and their incidence of hypoxia and hypotension was greater. tSAH patients spent more days in intensive care unit, more total days hospitalized, and had worse Glasgow Outcome Scale scores at acute hospital discharge. Fewer tSAH patients were discharged home, and almost 1.5 times as many tSAH patients died during hospitalization. Given a similar overall degree of injury at admission, patients with tSAH associated with a nonpenetrating head injury had a worse outcome than similar patients without tSAH.

Spinal cord injury often results in devastating physical, psychological, and economic disabilities. Research efforts are directed toward providing prognostic outcome data and animal models that parallel the human disorder, thereby elucidating the mechanisms responsible for its dismal clinical prognosis. Investigators continue to search for pharmacological agents that halt the cascade of events that lead to loss of function after cord injury. The scientific and federal regulatory processes by which new drugs are discovered and implemented clinically permit clinicians to evaluate the potential benefits of any new agent, and provide an estimate of the duration required for promising new agents to be made clinically available. Understanding these processes makes the task of classifying the availability status of new drugs much simpler, allowing rational dissemination of realistic information to patients and their families frequently made desperate for viable alternatives to the prospect of permanent paralysis. In this review, we describe the scientific and regulatory processes necessary for the clinical introduction of new drugs using spinal cord injury as an example. A classification scheme based on current Food and Drug Administration regulations is presented that provides drug availability status at a glance. It is hoped that such an organizational scheme will be of practical benefit to clinicians involved in the management of spinal cord-injured patients.

Study Design: A review of relevant literature and clinical experience with lumbar spinal disorder., Objectives: To discuss the indications for fusions and lumbar spinal disorders., Summary of Background Data: Fusion of the lumbar spine is performed frequently, but indications have not been defined clearly. The literature and the authors' experience with these indications are reviewed., Methods: A comprehensive review of the literature and the authors' clinical experience with lumbar spinal instability was critically examined. Specifically, the role of fusion, with or without instrumentation, versus decompression alone was assessed. From this, a set of definitive and relative indications for spinal arthrodesis in a variety of disorders of the lumbar spine could be established., Results: Once the diagnosis of lumbar spinal instability is established, fusion is indicated. However, fusion without spinal instrumentation has a high pseudarthrosis rate and poorer patient outcome. This spinal instrumentation should be used as an adjunct when considering spinal arthrodesis., Conclusions: Definitive indications for spinal fusions are trauma, tumor and infection, iatrogenic instability, or ischemic spondylolisthesis. Relative indications for fusions are degenerative spondylolisthesis, abnormal movement visualized on dynamic films with appropriate pain or neurologic deficit, and mechanical pain. Lumbar fusion is rarely indicated for routine discectomy, abnormal results of radiography without appropriate clinical findings, or stable spinal stenosis.

The presence of traumatic subarachnoid hemorrhage (tSAH) on admission computerized tomography (CT) scans obtained from patients suffering from severe, nonpenetrating head injury has been shown to be associated with a worse outcome than the injury alone would warrant. However, no previous study has provided a simple means of relating the amount of tSAH, its location, or other abnormal findings on initial head CT scans to outcome in patients with non-penetrating head injury. In this study, admission head CT scans from 252 patients with tSAH, treated at a single institution, were reviewed to ascertain thickness of the tSAH; its location; evidence of mass lesion(s); shift of midline structures (< or = 5 mm vs. > 5 mm); basal cistern effacement; and cortical sulcal effacement. The CT scans were then organized into Grades 1 to 4 with 1 indicating thin tSAH (< or = 5 mm); 2, thick tSAH (> 5 mm); 3, thin tSAH with mass lesion(s); and 4, thick tSAH with mass lesion(s). A stepwise regression analysis of CT features ranked them in descending order of contribution to Glasgow Outcome Scale (GOS) scores at the time of discharge from acute hospitalization as follows: basal cistern effacement, thickness of tSAH, cortical sulcal effacement, presence of mass lesion(s), and location of tSAH. A shift of midline structures was not found to be a significant variable. Further analysis comparing CT grades and admission postresuscitation Glasgow Coma Scale (GCS) scores was highly significant. Patients with lower CT grades had better admission GCS values and discharge GOS scores than those with higher CT grades. From their experience, the authors conclude that their CT grading scale is simple and reliable and relates significantly to outcome at the time of discharge from acute hospitalization.

Objective: Clinicopathologic evaluation of patients with lower extremity paraparesis/-plegia following rupture and repair of anterior communicating artery (ACoA) aneurysms., Design: Institution-based retrospective review., Setting: A tertiary neurologic referral center., Patients, Participants: Seven of 101 patients with subarachnoid hemorrhage from ruptured ACoA aneurysms treated between January 1987 and December 1992., Main Outcome Measures: Neurologic status at latest follow-up examination., Results: All patients presented with severe hemorrhage, poor clinical grade, and intracranial hypertension. Motor deficits developed within 7 days of aneurysm rupture and persisted for a mean duration of 39 days. Angiographic evidence of vasospasm in the anterior cerebral artery (ACA) distribution was documented in all cases, and paraparesis persisted beyond the angiographic resolution of vasospasm. All patients had evidence of frontal lobe dysfunction throughout their postoperative courses, and deep venous thrombosis and pulmonary emboli were common causes of morbidity and mortality. Autopsy data supported regional microvascular ischemia within the ACA distribution as the etiology of these motor deficits., Conclusions: The combination of vasospasm in the ACA distribution and lower extremity weakness associated with cognitive and affective impairment that resolves with time is common in patients with ACoA aneurysms. We propose that this constellation of clinical, radiographic, and pathologic findings be referred to as the "ACoA aneurysm paraparesis syndrome."

A hypothesis is proposed that (a) the skeletomotor basal ganglia-thalamocortical loop functions as a model of the behavior of the body and the environment, and that (b) dopaminergic neurons of the substantia nigra pars compacta comprise the substrates of an error distribution system projecting to the striatum. This error signal initiates the learning process in the basal ganglia - learning starts with increasing intensity of the error signal and is complete when the signal is minimized. Parkinson's disease (PD) may be considered as a disruption of learning processes in the basal ganglia that results from progressive degeneration of the substrate that is the error distribution system for this functional motor loop. Numerous clinical and experimental observations obtained from functional procedures for PD that show identical clinical effects in alleviating parkinsonian symptoms, e.g. thermocoagulative lesions and chronic stimulation, can be explained through the use of this conceptual theory of basal ganglia function. Because any controlling neural network must possess a model of the behavior of its controlled object, the heuristics outlined in this theory are broadly applicable for explaining the function of the nervous system, as well as being useful for planning surgical procedures and future strategies in functional neurosurgery.

Intracranial aneurysms in the pediatric population are rare lesions with a significant proportion occurring as giant aneurysms involving the vertebrobasilar system. The complex anatomy of these lesions frequently creates an extremely difficult management dilemma. We present two patients, a 9-year-old and a 13-year-old, with giant fusiform vertebrobasilar aneurysms, to illustrate the utility of cardiopulmonary bypass, hypothermic circulatory arrest and barbiturate cerebral protection for successful surgical treatment of these complex intracranial vascular lesions in children.

In each of 6 mature rats, unilateral rubrospinal tractotomy and hypoglossal neurectomy were done at one operative sitting. Paired operated animals were killed by formaldehyde and ethanol-acetic acid perfusion 3, 14 and 28 days later. One pair of unoperated control rats was perfused also. All rats were injected i.p. with [3H]thymidine 24 h before death. Immunohistochemical methods were applied to paraffin sections to visualize glial fibrillary acidic protein (GFAP) and transferrin in astrocytes and oligodendroglia, respectively. Microglia were demonstrated by both lectin-binding and histoautoradiographic methods. Neuroglia and nerve cells were counted in hematoxylin-eosin and azure B stains. Cell areas and the RNA concentration of hypoglossal neurons were determined by the Zeiss Image Scan System. Three days after hypoglossal neurectomy, increased astroglial staining (GFAP) and microglial hyperplasia (radiolabeled nuclei) were evident in the ipsilateral hypoglossal nucleus (HN). Microglial hyperplasia waned rapidly after 3 days and microglial numbers decreased. However, astroglial hypertrophy, demonstrable by GFAP staining, persisted 4 weeks postoperatively when astroglial processes were concentrated in a perineuronal position. Oligodendroglia were unaltered. In contrast to the HN, the axotomized red nucleus (RN) contained few radiolabeled microglia while a slight increase in GFAP-positive astroglial processes was seen only in animals killed 28 days postoperatively. Again, oligodendroglia were unchanged. In neither HN nor RN did axotomy cause nerve cell death. Although axotomized rubral neurons atrophy and become depleted of RNA, no statistically significant changes in somal size and RNA content of axotomized hypoglossal neurons occurred. The apparent absence of a neuroglial response of putatively supportive nature in the environs of axotomized rubral neurons may relate to their failure to regenerate. The neuroglial response likely is originated by the axotomized neuron and its absence may be an innate defect in the reaction of intrinsic neurons to axonic severance. Somas of axotomized peripherally projecting nerve cells appear to have the capacity to summon a neuroglial response.

It has been postulated that myelin degradation products may inhibit regrowth of mammalian central axons and that central nervous system (CNS) myelin and oligodendrocytes may constitute a "nonpermissive substrate" for axonal growth. To address these issues, we utilized an X-linked rat mutant, myelin-deficient or md. In the optic nerve of this mutant, 40 days and more postnatally, normal myelin is absent and oligodendrocytes are few (Dentinger et al. Brain Res. 344:255-266, 1985). Twenty-eight days before sacrifice, we operated on four groups of 50-day-old md rats and age-matched normal littermates according to the following protocols: 1) unilateral intraorbital optic nerve crush; 2) beginning within 1 hour of nerve crush, daily intraperitoneal injection of GM1 ganglioside (20 mg/kg) dissolved in phosphate-buffered saline (PBS); 3) daily intraperitoneal injection of PBS alone, also begun within 1 hour of nerve crush; 4) severance of the optic nerve immediately behind the papilla 16 or 21 days after the primary crush lesions. Additionally, normal and md rats were killed 4 and 14 days after unilateral optic nerve injury. Nerves of unoperated md rats and their normal littermates were also processed. In the operated animals that did not receive GM1, ultrastructural analysis 4, 14, and 28 days after lesioning revealed that md optic nerves contained significantly greater numbers of regenerating axons, including growth cones and varicosities, than nerves of normal rats. Notably, 28 days postoperatively, (group 1), regenerating axons were still abundant in md nerve, whereas, in nerves of normally myelinated littermates, axonal numbers were diminished markedly. Regenerating optic axons of both md and normally myelinated rats were oriented by linear astrocytic arrays and often were enclosed by astrocytic cytoplasm. In normal littermates, GM1 administration (group 2) induced a significant increase in the number of axons within the operative lesion. Paradoxically, GM1 inhibited the ordinarily robust regeneration of md axons. PBS-injected md and normal rats (group 3) showed no significant differences from noninjected, operated animals. Severance of the nerve at the papilla (group 4) 7-12 days before sacrifice confirmed the origination of axonal regrowth by retinal ganglion cells. The data provide in vivo support for a role of myelin breakdown products or the secretory products of oligodendroglia in the inhibition of regenerative axonal sprouting within mammalian CNS.

Regeneration and functional recovery of the hypothalamoneurohypophysial system (HNS) in neurohypophysectomized rats treated with either saline or vasopressin (VP) were analyzed utilizing specific immunohistochemical and physiological measures. Neural lobe ablation combined with VP administration precipitated a profound diabetes insipidus (following cessation of VP delivery) that persisted for the duration of the experiment. Diabetes insipidus was correlated with a drastic reduction in the number of VP-positive neurons in magnocellular hypothalamic nuclei. In contrast, large numbers of oxytocin (OT)-positive neurons survived neurohypophysectomy in VP-treated neurohypophysectomized rats; OT neurons accounted for the vast majority of magnocellular profiles observed in Nissl-counterstained sections. VP-immunoreactive fibers could be observed in limited quantities in the external lamina of the median eminence of VP-treated neurohypophysectomized rats, with little staining evident in the internal lamina. Saline-treated neurohypophysectomized rats exhibited the recovery of antidiuretic function characteristically seen following this lesion, with evidence of survival of considerable numbers of VP and OT neurons and median eminence hypertrophy. Both the internal and external laminae of the median eminence were densely innervated by large-caliber VP and OT fibers. Sham-operated animals receiving VP treatment did not show any long-term deficit in water metabolism, changes in the complement of VP or OT perikarya in hypothalamus, or changes in the innervation of the median eminence. Results indicate that VP treatment following neurohypophysectomy results in extensive retrograde degeneration of magnocellular VP neurons without affecting the survival of OT cells.

The rodent hypothalamic neurosecretory system normally exhibits remarkable functional and structural plasticity following injury. However, the present study describes a newly observed phenomenon in which neurohypophysectomized animals receiving chronically administered exogenous vasopressin during the post-lesion period (a treatment which insures maximal renal antidiuresis over this time frame) lose all capacity for recovery of antidiuretic function. Functional deficits are accompanied by a severe reduction in the number of neurons exhibiting immunohistochemical staining for arginine vasopressin. These data indicate that the presence of neurological stimulation signaling vasopressin release may play an important role in promoting neural regeneration of the vasopressinergic component of the neurosecretory system.

Fetal vasopressin neurons were grafted into adult Long-Evans rats with vasopressin deficiencies created by neural lobe ablation one week prior to implantation. Control animals and recipients with ectopic grafts still possessed significant deficits in fluid regulation 6 weeks following implantation. However, recipients with grafts fused to the host median eminence and containing magnocellular vasopressin neurons juxtaposed to the host portal vasculature showed restored peripheral vasopressin activity as measured by normal urine volumes and osmolalities. These findings suggest that structural integration of grafted neuroendocrine tissue with the appropriate target in the host brain is a necessary prerequisite for physiological activity.

This study investigated the mechanisms by which fetal hypothalamic transplants promote functional recovery in neurohypophysectomized rats. Seven days after neurohypophysectomy (resulting in urine osmolalities of about 800 mOsm), young adult male Long-Evans rats received either fetal hypothalamic grafts (n = 10) or sham transplants (n = 7). Recovery from the lesioned-induced diabetes insipidus was monitored for 6 months and then the transplant sites were evaluated by immunocytochemistry. Surviving host supraoptic magnocellular neurons and neurophysin-positive grafted neurons were counted and their formation of neurohemal contacts evaluated by retrograde transport of systemically injected horseradish peroxidase (HRP). There were significantly more surviving supraoptic magnocellular neurons in neurohypophysectomized animals with median eminence-placed grafts (2236 +/- 261 neurons/animal) than in animals with ectopic tissue grafts (895 +/- 142 neurons/animal) or sham implants (1052 +/- 92 neurons/animal). Almost all surviving host magnocellular neurons were labeled with retrogradely transported HRP while virtually none of the grafted neurophysin positive cells showed evidence of HRP uptake. The degree of functional recovery was directly correlated with the increased survival of host neurons. By 8 weeks post-transplantation, animals with median eminence-placed grafts had recovered from their diabetes insipidus and could concentrate their urine to within normal limits (2,120 +/- 110 mOsm). This recovery was stable for the remainder of the 6 month test period. In contrast, animals with ectopic grafts and sham transplants had permanent deficits in fluid regulation. Our results provide evidence for the long-term capacity of fetal neural tissue implants to rescue host neurons from the cell death that typically occurs in the mature central nervous system after axotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

While the cholinergic projection from the nucleus basalis to the cortical mantle has received considerable attention, a similar projection to the magnocellular basal nucleus of the amygdala has not been studied in such detail. The present study analyzed the cholinergic basal forebrain projection to the amygdala in the Cebus apella monkey by using combined tract-tracing and immunocytochemical techniques. As a foundation for this assessment, the morphological and cytoarchitectonic organization of the cholinergic telencephalic system of the New World C. apella monkey was examined by using choline acetyltransferase (ChAT) immunocytochemistry. Although there were minor differences, the telencephalic cholinergic system of Cebus monkeys is similar to that seen in Old World nonhuman primates. ChAT-immunoreactive neurons were observed throughout the Ch1-4 regions of the basal forebrain, with subdivisions of the Ch4 region similar to those previously described (Mesulam et al., '83a). Most cholinergic neurons were hyperchromic and magnocellular; however, some neurons were parvicellular. Like most species, cholinergic neurons were also observed throughout the striatum. However, unlike in rodents, cholinergic perikarya were not observed within the cortex or hippocampus. To analyze the cholinergic fiber projections from the basal forebrain to the amygdala, monkeys received an intraamygdaloid injection of the retrograde tracer horseradish peroxidase conjugated to wheat germ agglutinin. Retrogradely labeled neurons that colocalized ChAT or acetylcholinesterase (AChE) were found predominantly in the anterolateral portion of the CH4 region. Fewer double-labeled neurons were found in the anteromedial and intermediate portion of CH4 and in the CH3 region. Neurons that exhibited retrograde labeling were only occasionally discerned in the posterior portions of the CH4 region, in the medullary laminae of the globus pallidus, or lodged within the internal capsule. These data are discussed in terms of the putative role this cholinergic input might play in cognitive processing in primates.