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Biomedical subjects

M S Grady

Publications and source records attributed to M S Grady.

At least 55 records · Page 3Linked to original sources
PubMed1997

Fluid percussion injury causes disruption of the septohippocampal pathway in the rat.

Fluid percussion injury (FPI) causes memory deficits, loss of hippocampal neurons, and basal forebrain cholinergic immunoreactivity in rats. Basal forebrain septohippocampal projections terminate in specific hippocampal regions. The purpose of this study was to examine the effects of FPI on the septohippocampal pathway (SHP). Halothane-anesthetized rats received either a sham injury or a parasagittal FPI. To characterize the anatomical effects of FPI on the SHP, silver stains were performed on brains of animals at 1, 5, and 10 days following FPI and were compared to sham-injured preparations. To characterize the effects of FPI on retrograde transport in the SHP, a separate group of FPI and sham-injured animals with survival times of 2, 5, and 10 days received bilateral WGA-HRP injections into the hippocampal formation 24 h prior to sacrifice. Argyrophilic CA3 neurons were present 1 day following FPI. Five days following FPI, terminal degeneration was present in the inner third of the molecular layer of the dentate gyrus bilaterally that was not present 1 day after injury. Fiber and terminal degeneration was not observed in the basal forebrain until 10 days after FPI. WGA-HRP-labeled septal neurons decreased significantly (P < 0.05) ipsilateral to injury in animals sacrificed 5 and 10 days following FPI but not 2 days after injury. This investigation demonstrated that FPI produces focal injury in the hippocampal formation. In addition, the appearance of terminal degeneration in the dentate molecular layer correlated with the significant reduction in axonal transport 5 days following injury. This correlation illustrates the secondary processes that structurally damage the SHP up to 10 days after injury.

Animals↗
PubMed1997

Gunshot wounds of the internal carotid artery at the skull base: management with vein bypass grafts and a review of the literature.

BACKGROUND: Penetrating trauma to the skull base and distal cervical internal carotid artery (ICA) can result in occlusion or pseudoaneurysm formation. The appropriate management strategy for these rare lesions is controversial and includes observation, anticoagulation, carotid ligation, balloon occlusion, or revascularization. METHODS: We present the management and outcomes of four consecutive patients, two with pseudoaneurysms and two with acute occlusions, after injury to the distal cervical/petrous ICA from gunshot wounds. Preoperative assessment determined intracranial collateral flow patterns and the patency of the distal portion of the petrous ICA. RESULTS: Two patients underwent cervical-to-petrous ICA vein bypass grafts without neurologic complications. Both grafts remain patent without evidence of emboli at 2 years and 3 months, respectively. Both of the conservatively managed patients died, one from a massive cerebral infarction and the other from intracerebral hemorrhage. CONCLUSIONS: These cases underscore the need for an aggressive approach to the assessment and management of patients with penetrating vascular skull-base injuries. Although the optimal treatment of remains controversial, when the goal is exclusion of the injured portion of the carotid artery and revascularization, the cervical to petrous ICA vein bypass graft is a valuable management option that can reduce the potential morbidity and mortality from acute ischemic or delayed embolic or hemorrhagic complications, provide immediate restoration of high flow, and allow good surgical access with minimal risk to intracranial structures.

Adolescent↗
PubMed1997

Thrombotic, infectious, and procedural complications of the jugular bulb catheter in the intensive care unit.

OBJECTIVE: An assessment of the thrombotic, infectious, and technical complications of continuous jugular bulb catheter monitoring in the intensive care unit (ICU) was made. METHODS: Over a 1-year period, 44 patients suffering from traumatic brain injury, subarachnoid hemorrhage, or stroke received jugular bulb catheter monitoring in the ICU. They were followed for catheter insertion complications and the development of bacteremia. In 20 patients chosen randomly, an ultrasonographic evaluation was performed after removal of the catheter for an assessment of internal jugular vein thrombosis. RESULTS: Of the 44 patients, 1 became bacteremic; the source was identified as a thoracostomy site. Among the complications related to the 44 catheter insertions, there were 2 instances of carotid artery puncture (4.5%), 1 misplaced catheter (thoracic placement), and 1 clinically insignificant hematoma. Of the 20 patients investigated with ultrasonography, 8 (40%) had nonobstructive, subclinical internal jugular vein thrombi after jugular bulb catheter monitoring (95% confidence interval, 19-61%). The median monitoring duration was 3 days (range, 1-6 d). No clinical factor was identified to be associated with thrombus formation. CONCLUSION: We conclude the following: 1) the risk of bacteremia related to the jugular bulb catheter was negligible; 2) complications related to catheter insertion were rare and clinically insignificant; and 3) the incidence of subclinical internal jugular vein thrombosis after jugular bulb catheter monitoring is considerable. Although it is worthy to note this complication, no patient with a thrombus became symptomatic in the present series. The risk-benefit assessment of this monitoring technique must include consideration of subclinical thrombosis.

Adolescent↗
PubMed1997

Cerebral arteriovenous oxygen difference: a predictor of cerebral infarction and outcome in patients with severe head injury.

Jugular bulb oxygen monitoring can be used to estimate the adequacy of cerebral blood flow to support cerebral metabolism after severe head injury. In the present study, the authors studied the cerebral arteriovenous oxygen difference (AVDO[2]) before and after treatment in 32 head-injured patients (Glasgow Coma Scale scores < or = 8) to examine the relationships among AVDO and cerebral perfusion pressure (CPP), delayed cerebral infarction, and outcome. Fifteen patients (Group A) underwent craniotomy for hematoma evacuation and 17 (Group B) received mannitol for sustained intracranial hypertension (intracranial pressure > 20 mm Hg, > 10 minutes). Radiographic evidence of delayed cerebral infarction was observed in 14 patients. Overall, 17 patients died or were severely disabled. Cerebral AVDO(2) was elevated before craniotomy or mannitol administration; the mean AVDO(2) for all patients before treatment was 8.6 +/- 1.8 vol%. Following craniotomy or mannitol administration, the AVDO(2) decreased in 27 patients and increased in five patients (mean AVDO(2) 6.2 +/- 2.1 vol% in all patients; 6 +/- 1.9 vol% in Group A; and 6.4 +/- 2.4 vol% in Group B). The mean CPP was 75 +/- 9.8 mm Hg and no relationship with AVDO(2) was demonstrated. Before treatment, the AVDO(2) was not associated with delayed cerebral infarction or outcome. By contrast, a limited improvement in elevated AVDO(2) after craniotomy or mannitol administration was significantly associated with delayed cerebral infarction (Group A: p < 0.001; Group B: p < 0.01). Similarly, a limited improvement in elevated AVDO(2) after treatment was significantly associated with an unfavorable outcome (Group A: p < 0.01; Group B: p < 0.001). In conclusion, these findings strongly indicate that, despite adequate cerebral perfusion, limited improvement in elevated cerebral AVDO(2) after treatment consisting of either craniotomy or mannitol administration may be used to help predict delayed cerebral infarction and poor outcome after traumatic brain injury.

Adult↗
PubMed1996

Improvement in the organ donation rate at a large urban trauma center.

OBJECTIVE: To implement and then determine the efficacy of a "hospital development" (HD) plan designed to increase organ donation rates at an urban trauma center. DESIGN/SETTING: Retrospective reviews of all deaths at an urban, level I trauma center for 1991 to 1994. SUBJECTS: Potential organ donors were identified by standardized criteria, and the reasons why potential donors did not become actual organ donors ("nonproductive donors") were categorized. Actual donors were defined as individuals in whom one transplantable organ was recovered. Results also were expressed as percentages of potential donors for each year. Changes in actual donor numbers and in nonproductive donor categories were compared for the "pre-HD" (1991-1992) and "post-HD" (1993-1994) periods. INTERVENTION: The HD plan had six components: identification of key contact individuals, development and modification of relevant hospital policies, improvement in procurement agency visibility in hospital units, education of hospital staff regarding organ donation, institution of early on-site donor evaluations, and provision of feedback to hospital staff about the disposition of potential organ donors. RESULTS: Institution of the HD plan was associated with a highly significantly increase in actual donors for the post-HD period as compared with the pre-HD period (P < .001), and pre-HD and post-HD donor rates were 26.1% and 49.5%, respectively. This increase was due primarily to a marked improvement in hospital staff identification and referral of potential donors (P < .001). CONCLUSIONS: A coordinated plan incorporating continuing staff education, organ donation policy refinement, and increased visibility and availability of organ procurement agency personnel can substantially increase organ donation at an urban trauma center.

Feedback↗
PubMed1996

The incidence of surgical complications is similar in good and poor grade patients undergoing repair of ruptured anterior circulation aneurysms: a retrospective review of 355 patients.

To determine how clinical grade after subarachnoid hemorrhage impacts operative characteristics and the incidence of intra- and postoperative surgical complications, we retrospectively compared the surgical management of all good grade (n = 224) and poor grade (n = 131) patients who suffered ruptured anterior circulation aneurysms between 1983 and 1993. The majority of good grade (74.2%) and poor grade (89.8%) patients underwent surgery < 3 days after subarachnoid hemorrhage. The results in this series demonstrate that severe cerebral swelling, often secondary to intracerebral hemorrhage, was significantly more frequent in poor grade patients. The incidence of complications, such as failure to occlude the aneurysm, major vessel occlusion, intraoperative aneurysm rupture, or surgical contusion, however, was similar in poor grade and good grade patients. We conclude, therefore, that except for severe cerebral swelling associated with intracerebral hemorrhage, the risk of surgical complications is similar in good and poor grade patients undergoing surgical repair of ruptured anterior circulation aneurysms.

Aneurysm, Ruptured↗
PubMed1996

Magnetic neurosurgery.

Because of the complex shape of many brain structures, the ideal brain probe would be highly flexible and give the neurosurgeon the ability to independently and precisely control movement of the probe tip. A magnetic surgery system has been developed that implements this concept. Flexible brain probes with small permanent magnetic tips are placed on the brain surface through a small burr hole and then magnetically manipulated within the brain. Drive forces are produced by an array of six superconducting magnets suspended within a cryostatic helmet. They produce a maximum force of 3 times the threshold needed to move the probe through the parenchymal tissues at its normal speed of 1 mm/s. Computer-controlled magnetic impulses precisely direct the probe movement in any direction desired with movement accuracy of 0.47 mm in phantom gels. Probe position is monitored 3 times per second with orthogonally oriented microchannel plate X-ray systems, X-ray dose from a 3-hour simulated procedure is comparable to that of a chest X-ray. In vivo and in vitro feasibility studies have been carried out in dog and pig brains. Preclinical trials are planned for clinical applications including implantation of flexible brachytherapy threads.

Equipment Design↗
PubMed1996

Posterior instrumentation of the unstable cervicothoracic spine.

Fractures, tumors, and other causes of instability at the cervicothoracic junction pose diagnostic and treatment challenges. The authors report on 23 patients with instability of the cervicothoracic region, which was treated with posterior plate fixation and fusion between the lower cervical and upper thoracic spine. During operation AO reconstruction plates with 8- or 12-mm hole spacing were affixed to the spine using screws in the cervical lateral masses and the thoracic pedicles. Postoperative immobilization consisted of the patient's wearing a simple external brace for 2 months. The following parameters were analyzed during the pre- and postoperative treatment period: neurological status, spine anatomy and reconstruction, and complications. Follow up consisted of clinical and radiographic examinations (mean duration of follow up, 15.4 months; range, 6-41 months). No neurovascular or pulmonary complications arose from surgery. All patients achieved a solid arthrodesis based on flexion-extension radiographs. There was no significant change in angulation during the postoperative period, but one patient had an increase in translation that was not clinically significant. There were no hardware complications that required reoperation. One patient requested hardware removal in hopes of reducing postoperative pain in the cervicothoracic region. One postoperative wound infection required debridement but not hardware removal. The authors conclude that posterior plate fixation is a satisfactory method of treatment of cervicothoracic instability.

Adult↗
PubMed1996

Predicting outcome in poor-grade patients with subarachnoid hemorrhage: a retrospective review of 159 aggressively managed cases.

To determine what factors predict outcome, the authors retrospectively reviewed the management of all 159 poor-grade patients admitted to Harborview Medical Center at the University of Washington who suffered aneurysmal subarachnoid hemorrhage between 1983 and 1993. Favorable outcome (assessed by the Glasgow Outcome Scale) occurred in 53.9% of Hunt and Hess Grade IV, and 24.1% of Grade V patients. Outcome was largely determined by the initial hemorrhage and subsequent development of intractable intracranial hypertension or cerebral infraction. Using multivariate analysis, the authors developed three models to predict outcome. It was found that predicting outcome based only on clinical and diagnostic criteria present at admission may have resulted in withholding treatment from 30% of the patients who subsequently experienced favorable outcomes. It is concluded that aggressive management including surgical aneurysm obliteration can benefit patients with poor neurological grades and should not be denied solely on the basis of the neurological condition on admission.

Adolescent↗
PubMed1996

Predicting length of hospital stay and cost by aneurysm grade on admission.

To determine the relationship between clinical grade on admission and treatment cost after aneurysm rupture, the authors retrospectively examined the length of hospital stay (LOS) and total hospitalization costs (excluding professional fees) for 543 patients admitted for aneurysm surgery between 1983 and 1993. The overall median LOS was 18 days, with a range of 1 to 165 days. Increased median LOS correlated with Hunt and Hess Grades 0 to IV on admission (p < 0.001). Median LOS for Grade V patients was reduced, in part, because of early mortality. Increased treatment cost also correlated with worse admission clinical grade (p < 0.001). A significant proportion of total expenditures occurred early in the hospitalization for patients in all clinical grades. Identification of additional factors affecting the cost of aneurysm treatment is indicated to complement treatment outcome studies.

Adolescent↗
PubMed1996

Epidural hemorrhage: is it abuse?

OBJECTIVE: To determine whether children presenting with epidural hemorrhage (EDH) are as likely to have been abused as are children presenting with subdural hemorrhage (SDH). DESIGN: Retrospective chart review. SETTING: Level I regional trauma center and a regional children's hospital. PATIENTS: All children at both institutions 3 years old or younger with a diagnosis of EDH or SDH identified by a search of the computerized trauma registry and hospital medical records from 1985 through 1991. MEASUREMENT AND RESULTS: Complete records were found for 93 of 94 eligible subjects. The diagnosis of accidental or inflicted injury was ascertained from the patient's hospital medical record or the records of Child Protective Services. Of all subjects (n = 93), 52% (48/93) were male and the median age was 15 months. Abuse was diagnosed in 47% (28/59) of children with SDH and 6% (2/34) of those with EDH. Other significant injuries were found in 47% of children with SDH and 18% of children with EDH. There was no statistically significant difference between the two groups with respect to the likelihood of identifying a skull fracture, the need for surgical evacuation of the hemorrhage, or mortality. CONCLUSIONS: Our data are consistent with current biomechanical concepts of intracranial injury. EDHs results from brief linear contact forces that commonly occur in unintentional falls. SDHs are caused by global high-energy rotational acceleration/deceleration forces that are commonly generated in episodes of abuse. Compared with SDH, EDH rarely results from abuse.

Acceleration↗
PubMed1995

Review of magnetic neurosurgery research.

Image guided surgical techniques are often used to provide useful localizing information during the course of otherwise "standard" surgical procedures. In this review, a magnetic surgery system (MSS) is described that couples image guidance methods with a novel magnetic treatment delivery system. The MSS was designed with the unique capacity to manipulate an implant remotely, to follow complex curvilinear paths, and to implement serial movements over time without reoperation. Magnetically tipped intracerebral implants are placed on the brain surface and then directed along a target trajectory by means of externally generated magnetic gradients. The location of the implant is calculated by comparing preoperative magnetic resonance imaging (MRI) imaging data with intraoperative biplanar fluoroscopic images. A command computer presents the surgeon with relevant MRI-derived images and implements movement commands by sending currents of various strength to the six superconducting magnets suspended about the subject's head. The results of multidisciplinary preclinical research and development work are reviewed.

Brain↗
PubMed1995

Functional design features and initial performance characteristics of a magnetic-implant guidance system for stereotactic neurosurgery.

A helmet with a roughly cubic array of six super-conducting coils is used to apply force on a small permanent magnet pellet in brain or in brain phantom material. This apparatus, called the Magnetic Stereotaxis System, will be used to deliver drugs and other therapies directly into deep brain tissues, under control of a computer and fluoroscopic imaging system. This paper considers only the force application aspects of the instrument. The primary design features of the helmet and power supply controls are presented, along with field plot data and single-axis motion results. The field plot data show that agreement with the finite-element iron-free field calculations is sufficiently high (> 1%) for the instrument. These preliminary motion data indicate accuracy better than 2 mm for the impulsive pellet motion, even though the visual position observations had significantly greater error than the completed imaging system will have. The companion paper will take up analysis of the control aspects of the motion, and our recent solutions to difficulties found in the experimental work described here.

Brain↗
PubMed1995

Characteristics of an improved magnetic-implant guidance system.

The previous companion paper described the motivation, design, and early experiments of a Magnetic Stereotaxis System. The part of the system considered in these papers is a helmet with a roughly cubic array of six superconducting coils used to apply force on small permanent magnet pellets in brain and in brain phantom material. This apparatus will be used to deliver drugs and other therapies directly into deep brain tissues, under control of a computer and fluoroscopic imaging system. Here, we analyze the general stability problems of controlling the currents in the coils for impulsive stepwise motion of the pellet, subject to quench avoidance in the superconducting coils, and in the face of Earnshaw's theorem governing stability in static magnetic fields. We also describe solutions that have been found to the primary difficulties limiting controlled pellet motion in the studies presented in the companion paper.

Brain↗