Alterations in brain norepinephrine metabolism induced by environmental stimuli previously paired with inescapable shock.

Footshock stress produced an immediate increase in brain concentrations of 3-methoxy-4-hydroxyphenylglycol sulfate (MHPG-SO4), a major metabolite of the neurotransmitter norepinephrine, in the rat brain. Twenty-four hours after footshock stress, when concentrations had returned to baseline, increases in MHPG-SO4 and emotional behavior could be elicited by previously neutral environmental stimuli that had been paired with the stress.

Robotic assisted spinal surgery--from concept to clinical practice.

After several years of product development, animal trials and human cadaver testing, the SpineAssist--a miniature bone-mounted robotic system--has recently entered clinical use. To the best of the authors' knowledge, this is the only available image-based mechanical guidance system that enables pedicle screw insertion with an overall accuracy in the range of 1 mm in both open and minimally invasive procedures. In this paper, we describe the development and clinical trial process that has brought the SpineAssist to its current state, with an emphasis on the various difficulties encountered along the way and the corresponding solutions. All aspects of product development are discussed, including mechanical design, CT-to-fluoroscopy image registration, and surgical techniques. Finally, we describe a series of preclinical trials with human cadavers, as well as clinical use, which verify the system's accuracy and efficacy.

Catecholamine metabolism during heroin use.

The authors examined urinary levels of catecholamines and metabolites during a 10-day period of heroin use in 9 subjects. Catecholamine and metabolite excretion increased over baseline values on the first day of heroin use, but markedly different patterns of change emerged later. In contrast to the significant increase in normetanephrine and decrease in metanephrine excretion in all 9 subjects during heroin use, only 4 subjects showed an increase in 3-methoxy-4-hydroxyphenyl glycol (MHPG) excretion. Moreover, it appeared that the increase in MHPG excretion in this subgroup began on the day before heroin administration, which suggests the possibility of an anticipatory or conditioned response.

The medial acetabular wall: normal measurements in different population groups.

Measurements of the acetabulum and particularly the medial acetabular wall were done on 90 skeletons. Mean and standard deviations for different population groups are presented. The purpose of this study was to establish the normal range of values for the thickness of the medial wall of the acetabulum. This information is of value for the radiologist and the orthopaedic surgeon in the pre- and intraoperative assessment of the bone reserve of the acetabular fossa in hip surgery.

The treatment of tardive dyskinesia with baclofen.

Thirty-one psychiatric outpatients with tardive dyskinesia (TD) on neuroleptic medication were followed in a double-blind, randomized trial comparing baclofen (30-90 mg per day) to placebo. A repeated measures analysis of variance revealed no statistical difference between the baclofen-treated group and the placebo group for the total Abnormal Involuntary Movement Scale (AIMS) scores. There was a trend (P = 0.09) for an initial improvement, then a worsening of frequency counts across four visits. The authors attempt to explain this finding on the basis of information obtained from animal research.

Alterations in brain norepinephrine metabolism and behavior induced by environmental stimuli previously paired with inescapable shock.

After exposure to a single session of inescapable footshock, rats show deficits in escape performance 24 h later when required to lever press on a fixed ratio (FR-3) schedule. Footshock stress produces an immediate increase in brain levels of 3-methoxy-4-hydroxyphenylglycol sulfate (MHPG-SO4), a major metabolite of norepinephrine in rat brain. Twenty-four hours after a single or repeated session(s) of footshock stress, when levels of MHPG-SO4 returned to baseline, increases in brain levels of MHPG-SO4, crouching and defecation behavior were elicited in rats by neutral environmental stimuli that had been previously paired with inescapable footshock stress. These results suggest that sensitization or conditioning of noradrenergic neuronal systems may be induced by environmental stimuli previously paired with stress, and may help to explain, at least in part, the deficits in escape performance observed 24 h after exposure to inescapable shock.

Immediate vs. long-term desmethylimipramine or chlorimipramine: effects on regional cerebral blood flow.

The immediate vs. long-term effects of desmethylimipramine (DMI) or chlorimipramine (CMI) on cerebral blood flow (CBF) were determined in 17 rabbit brain regions using radioactively tagged microspheres (15 +/- 3 micron in diameter). A single administration of either drug did not alter average CBF or its regional distribution 1 h later. Desmethylimipramine, an agent which primarily blocks re-uptake in presynaptic noradrenergic neurons, significantly increased CBF when administered daily for 21 consecutive days. The regional effects of DMI were not restricted to those areas dense in noradrenergic receptors. Flow was significantly increased in the hypothalamus, olfactory cortex, globus pallidus-putamen and midbrain. These flow increases probably reflect integrated cerebral metabolic, synthetic and/or functional activity which were associated with altered receptor sensitivity and/or number, rather than a direct cerebral vasodilatory effect. In contrast, CMI, a tricyclic antidepressant which primarily blocks presynaptic re-uptake in serotonergic neurons, and produced sedation, had little effect on CBF when administered daily for 21 consecutive days. The immediate effects of these agents on presynaptic re-uptake was not associated with altered CBF. The long-term antidepressant activity of these two agents on receptor sensitivity was probably not correlated with CBF, as evidenced by the lack of effect which CMI had on this parameter. Rather, CBF response appears to be correlated with the therapeutic spectrum of DMI which increases psychomotor activity in retarded depression.

Baclofen in tardive dyskinesia patients maintained on neuroleptics.

Several short-term trials of baclofen for tardive dyskinesia have yielded conflicting results. We evaluated 33 patients maintained on a constant dose of neuroleptic during a randomized 6-week double-blind placebo-controlled trial, followed by a 6-week open-label trial. During the double-blind part, 67% of baclofen-treated patients and 47% of placebo-treated patients showed a reduction of 25% or more in their original dyskinesia score on the abnormal involuntary movement scale. In the open-labeled part, we further evaluated seven of nine baclofen responders and nine of nine placebo nonresponders. We found a 77% baclofen response rate for the original placebo nonresponders, a loss of efficacy in 23% of the original baclofen responders, and an attenuation of response in others. Patients with major depressive disorders were poorer responders to baclofen than those with schizophrenia. Side effects were infrequent and reversible, but dose limiting in several instances. Although baclofen may help some cases of mild tardive dyskinesia, its efficacy may attenuate with long-term administration.

Anatomy of the normal knee as seen by magnetic resonance imaging.

Nuclear magnetic resonance imaging (MRI) was used to study the normal knee. As well as revealing bone quality, MRI provided useful information on intra-articular and extra-articular soft tissues. Midsagittal views gave clear images of the cruciate ligaments, and of the patellar and quadriceps tendons. Parasagittal views were the best for delineating the menisci which, like ligaments and tendons, are of low intensity; the semimembranosus tendon and its insertion to the proximal tibia were also seen clearly in these views. The cruciate ligaments and menisci, though visible in the coronal view also, were better seen in the sagittal view. Axial views provided information on the structure of the patella, its cartilage, the patellofemoral joint and posterior soft-tissue structures.

Bilateral intraosseous ganglia of the scaphoid and lunate bones.

A rare case of simultaneous bilateral intraosseous ganglia of the scaphoid and lunate bones is presented. The cysts were removed and the carpal bones were grafted with cancellous bone, resulting in a satisfactory outcome.

Evaluation of a novel tourniquet device for bloodless surgery of the hand.

This study evaluates a new device (S-MART ) for exsanguination and occlusion of the blood flow to the arm for hand surgery. The device consists of a silicone ring wrapped within a sterile stockinette and pull straps. It is applied by placing it on the patient's fingers and rolling it up the limb to the desired occlusion site by pulling on the straps. The time for placement and removal of the device was measured during trigger release and carpal tunnel surgery and the quality of exsanguination was evaluated. The device could be placed and removed quickly and provided an excellent bloodless field. At follow-up examination no signs or symptoms were seen at the site of the S-MART occlusion and no complications were observed in any patient.

Cementless coated and noncoated Mathys acetabular cups: radiographic and histologic evaluation.

This study evaluated 185 cementless Mathys coated and uncoated acetabular cups inserted for total hip replacement since September 1984. All of the cups were high-density polyethylene. Sixty were uncoated (group A), 96 were coated with hydroxyapatite (group B), and 29 were coated with titanium (group C). Cup survival was assessed clinically, histologically, and radiographically, and a computer-assisted EBRA method was used to evaluate cup migration. After a mean follow-up of 8 years, five cups in group A that had previously shown migration were revised as a result of aseptic loosening, while no loosening of hip sockets occurred in groups B and C. These results suggest that Mathys cups should be used only if coated with hydroxyapatite or titanium. Furthermore, the histologic evaluation in four cups from groups B and C revealed normal bone formation without inflammation or fibrotic tissue around the cups, promising long-term survival.

Humeral fracture following shoulder arthroplasty.

Fracture of the humeral shaft after total or hemiarthroplasty of the shoulder occurs infrequently but has serious consequences. This article reports on five patients with ipsilateral humeral fractures following shoulder hemiarthroplasty who were treated either conservatively or surgically. Fractures in the three patients treated conservatively healed on average by 7 months. The results were satisfactory in one patient and unsatisfactory in two patients. Both of these patients complained of pain and limitation of shoulder motion. Fractures in the two patients treated by open reduction and Mennen plate fixation healed on average by 2 months, resulting in a better outcome for these patients treated surgically.

The effect of intramedullary bone plug on femoral stem migration of hydroxyapatite-coated hip arthroplasty.

This study investigated the effect of intramedullary corticocancellous bone plug on the fixation and stability of hydroxyapatite-coated femoral stems in total hip arthroplasty (THA). Intramedullary corticocancellous bone plug was used in 30 patients with hydroxyapatite-coated femoral stems (group A) and a consecutive series of 30 patients with hypdroxyapatite-coated stems without bone plug served as the control group (group B). Patients underwent clinical and radiographic follow-up for at least 2 years. The addition of corticocancellous bone plug to the hydroxyapatite-coated stem significantly improved clinical and radiographic results. The mean Harris Hip Score at 3 and 6 months postoperatively was 92 and 94 in group A, and 84 and 87 points in group B (P<.004 and P<.001, respectively). There was no significant difference between groups at 1 year postoperatively and thereafter. The predominant cause for the difference was the thigh pain score, which was reduced at both 3 and 6 months in group A compared to group B (P<.01 and P<.05, respectively). There also were statistical differences between the two groups regarding radiographic signs. The evidence of endosteal bone formation in group A patients was superior at 3 and 6 months (P<.001 and P<.01, respectively). The appearance of a radiolucent line was significant in group B patients at 3 and 6 months (P<.001). Femoral stem migration of 3 mm was noted in three group B patients versus no group A patients (P<.05). These short-term clinical and radiographic results suggest corticocancellous bone plug can provide early pain relief and durable implant fixation, but long-term follow-up should be considered.

The effect of abduction differences between cup and contralateral acetabular angle on polyethylene component wear.

One hundred forty-two patients who underwent cemented or uncemented hip replacement were studied radiographically to determine acetabular component wear. Mean duration of follow-up was 58 months (range: 35-92 months). Average linear wear was 0.78 mm (range: 0-1.9 mm), and average wear rate was 0.16 mm/year (range: 0-0.45 mm/year). An increased wear rate per year correlated with a discrepancy >18.3 degrees between contralateral acetabular angle and acetabular cup inclination (P<.005). Statistical analysis revealed no significant correlation between cup inclination and polyethylene wear, which was studied without considering the contralateral hip (P>.3). There was no relationship between polyethylene wear and cup design, weight, and initial polyethylene thickness.

Fracture of the femur after total hip arthroplasty.

The classification and treatment of ipsilateral femur fractures after total hip arthroplasty are described on the basis of the predicted stability of the implant after the fracture. Conservative treatment was successful in most cases.

Revision arthroplasty of femoral cortex defect using a noncemented stem, Mennen plate, and bone graft.

Twelve patients who underwent total hip replacement complicated by aseptic loosening with severe bone loss were included in this study. Two patients had aseptic loosening of the second revision, six of the third revision, and the remaining four patients of the fourth revision total hip replacement. In all patients, the radiographs revealed an extremely thin cortex around the stem of the prosthesis and almost complete disappearance of one cortex. All patients were treated by revision total hip replacement in conjunction with Mennen plate fixation and allograft bone support. The allograft bone support included three cortical struts and nine massive bone grafts that used cement as a strew. The results were satisfactory in 10 patients in respect to functional activity, pain and radiographic evaluation. In two patients who underwent their fifth revision, the results were unsatisfactory but better than before the operation. Mennen plate fixation provides a sufficient and easy technique for aseptic loosening of total hip replacement with severe bone loss. By preserving the periosteal blood supply, the time required for bone graft incorporation is shortened, resulting in an early final outcome.

Peroneal intraneural ganglion.

An intraneural cyst is a rare condition. This paper describes one such case, discusses the clinical picture and possible etiology, and reviews the methods of treatment reported in the literature.

Breakage of the metal tray in total knee replacement.

Breakage of the metal tray of the tibial component for total knee arthroplasty is reported here for the first time. Metallurgic analysis defined the reason for this rare complication.

Intertrochanteric fractures in high risk geriatric patients treated by external fixation.

Conservative treatment in intertrochanteric fractures of the high risk patient carries a high rate of mortality and morbidity. In the present study external fixation of the fracture was performed under local or light general anaesthesia. This is a safe procedure and permits immediate full weight bearing.