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Optic nerve sheath decompression: a clinical review and proposed pathophysiologic mechanism.

Surgical decompression of the intraorbital meningeal sheath of the optic nerve has undergone a recent resurgence of interest. Previously, the procedure had been reserved only for the most desperate cases of severe visual loss associated with chronic papilloedema. However, recent investigations have demonstrated the operation's efficacy not only for chronic papilloedema and pseudotumor cerebri, but also for the optic neuropathy associated with the acute retinal necrosis syndrome, traumatic subdural haematomas of the optic nerve and progressive nonarteritic ischaemic optic neuropathy. In this article, we review the previous literature concerning optic nerve sheath decompression, the indication for the procedure, its techniques and results. Finally, we propose that optic nerve sheath decompression may be effective for what appear to be very different optic neuropathies because the operation may reverse optic nerve ischaemia, a common pathophysiologic feature of all these disorders.

Humans↗

Pitfalls in carpal tunnel decompression.

In the period 1972 to 1977, 35 patients with persistent pain and other disabilities after carpal tunnel decompression were referred for treatment. The pitfalls included: (i) wrong diagnosis--5 patients; (ii) inadequate decompression--9 patients; (iii) recurrent compression--4 patients; (iv) iatrogenic nerve injury--7 patients; and (v) postoperative complications--10 patients. The patients in Groups 1 and 5 were treated by non-operative measures. Most of the patients in Groups 2, 3, and 4 were treated by reoperation. This paper outlines the causes and prevention of pitfalls in carpal tunnel decompression.

Adolescent↗

Retrobulbar pressures measured during surgical decompression of the orbit.

AIMS/BACKGROUND: In Graves' ophthalmopathy the increase in volume of intraocular muscles and fat will cause elevated intraorbital pressure. In order to investigate the pressure levels involved, intraorbital pressure, or retrobulbar pressure (RBP) was measured continuously in orbits of patients with Graves' ophthalmopathy during surgical decompression. METHODS: Retrobulbar pressure was measured before and during surgical decompression using an intraorbitally applied pressure transducer. RESULTS: In eight patients with dysthyroid optic neuropathy (DON) RBPs between 17 and 40 mm Hg were recorded. At the end of the surgical procedure the mean RBP was reduced from 28.7 mm Hg to 18.7 mm Hg, the decrease ranging from 8 to 12 mm Hg, which showed a high correlation with the starting pressures (p < 0.001). In two cases without DON, pressures were 11 and 9 mm Hg. Forces exerted by spatula manipulation usually resulted in a RBP level of more than 70 mm Hg. CONCLUSIONS: This study shows that RBPs are markedly elevated in Graves' ophthalmopathy and that surgical decompression can result in a significant reduction in the intraorbital pressure. Optic nerve dysfunction in Graves' ophthalmopathy may not be caused exclusively by the direct pressure of swollen extraocular muscles upon the optic nerve, but also by a raised RBP. It is hypothesised that the damage inflicted upon the optic nerve can be caused in consequence by RBP induced incarceration of the nerve, compressed by surrounding periosteal lined orbital fat bulging posteriorly into the entrance of the optic canal.

Female↗

Coronal approach for rehabilitative orbital decompression in Graves' ophthalmopathy.

AIMS: To determine the effectiveness and safety of three wall orbital decompression by the coronal approach in Graves' ophthalmopathy. METHODS: The records of 125 patients with Graves' ophthalmopathy, who had undergone three wall orbital decompression by coronal approach between April 1984 and October 1993, were studied retrospectively. Special attention was paid to proptosis reduction, changes in ocular motility, and complications. RESULTS: The preoperative Hertel values ranged from 15 to 30 mm (mean 22.43 mm). The mean proptosis reduction was 4.34 mm (range 0-10 mm). Proptosis reduction in patients with preoperative Hertel values higher than 27 mm was significantly more than in patients with preoperative values between 25 and 27 mm (p < 0.05). This last group showed significantly more proptosis reduction than patients with preoperative Hertel values of 23 and 24 mm (p < 0.01). Postoperatively, 3.2% of the patients showed new diplopia in primary and/or reading position. In 4% of the patients with normal ocular motility preoperatively, diplopia in the extreme directions of gaze developed. In 4% of the patients, preoperative motility disturbances decreased or disappeared postoperatively. CONCLUSION: Three wall orbital decompression by coronal approach is a safe and effective technique, to achieve proptosis reduction in patients with Graves' ophthalmopathy, with fewer complications than other techniques thus far described.

Adolescent↗

Selective transplenic decompression of oesophageal varices by distal splenorenal and splenocaval shunt.

The usefulness of selective transplenic decompression of oesophageal varices by distal splenorenal shunt and splenocaval shunt was evaluated in the control of gastrointestinal haemorrhage in patients with portal hypertension of varied aetiology. (Decompression was successful in 69 out of 78 cases.) It was shown that it is superior to total portosystemic shunts, as the incidence of encephalopathy was very low compared with the data from our series of portocaval shunts. The operative mortality has been progressively lowered and has now reached levels comparable with portocaval shunt. Distal splenorenal shunt when performed as an emergency procedure to arrest bleeding has limited usefulness but when performed as an elective or prophylactic procedure its results are comparable with those of portocaval shunt without the untoward complications such as encephalopathy. A modified selective decompression of varices has been described in which the distal end of the splenic vein is anastomosed to the inferior vena cava. Though no long term follow-up studies are available, we believe that this shunt is likely to prove superior to distal splenorenal shunt as it has both the advantages of the distal splenoral and the haemodynamic advantage of end-to-side portocaval shunt. We conclude that in patients with portal hypertension of varied aetiology, who have not had a haemorrhagic episode but in whom varices have been demonstrated or who have had one episode of haemorrhage from varices, the splenocaval shunt when feasible or the distal splenorenal shunt offers the optimal method of management at present in India.

Adolescent↗

Transcatheter closure of patent foramen ovale using the Amplatzer septal occluder to prevent recurrence of neurological decompression illness in divers.

OBJECTIVE: Large flap valve patent foramens may cause paradoxical thromboembolism and neurological decompression illness in divers. The ability of a self expanding Nitinol wire mesh device (Amplatzer septal occluder) to produce complete closure of the patent foramen ovale was assessed. PATIENTS: Seven adults, aged 18-60 years, who had experienced neurological decompression illness related to diving. Six appeared to have a normal atrial septum on transthoracic echocardiography, while one was found to have an aneurysm of the interatrial septum. METHODS: Right atrial angiography was performed to delineate the morphology of the right to left shunt. The defects were sized bidirectionally with a precalibrated balloon filled with dilute contrast. The largest balloon diameter that could be repeatedly passed across the septum was used to select the occlusion device diameter. Devices were introduced through 7 F long sheaths. All patients underwent transthoracic contrast echocardiography one month after the implant. RESULTS: Device placement was successful in all patients. Device sizes ranged from 9-14 mm. The patient with an aneurysm of the interatrial septum had three defects, which were closed with two devices. Right atrial angiography showed complete immediate closure in all patients. Median (range) fluoroscopy time was 13.7 (6-35) minutes. Follow up contrast echocardiography showed no right to left shunting in six of seven patients and the passage of a few bubbles in one patient. All patients have been allowed to return to diving. CONCLUSION: The Amplatzer septal occluder can close the large flap valve patent foramen ovale in divers who have experienced neurological decompression illness. Interatrial septal aneurysms with multiple defects may require more than one device.

Adult↗

The benefits of percutaneous cholecystostomy for decompression of selected cases of obstructive jaundice.

Eleven selected patients with obstructive jaundice underwent percutaneous cholecystostomy (PC) for decompression. Ten of these patients had the constellation of distal common duct obstruction, nondilated or minimally dilated intrahepatic ducts, and a distended gallbladder; one patient with a bleeding dyscrasia had moderately dilated intrahepatic bile ducts. All procedures were successful and effective, and 10 of 11 cholecystostomies were performed within 5-15 minutes. No specific complications occurred. The success, ease, and safety of the procedure indicate primary use of PC for biliary decompression when the intrahepatic bile ducts are minimally dilated or nondilated, because standard transhepatic biliary drainage may be difficult in these cases. Because cannulation of the cystic duct and hence internalization through the tumor may be difficult, PC may be most valuable preoperatively, or before standard percutaneous biliary drainage, or as an alternative to endoscopic drainage. This is a rapid and safe method with which to achieve biliary decompression, especially with minimally dilated or nondilated intrahepatic bile ducts.

Adult↗

Standard surgical approaches to primary choledocholithiasis--definitive versus temporary decompression.

The occurrence of retained/recurrent calculi after primary CBDE followed by temporary T-tube decompression, have remained at rates varying from 5.4% to 20.9% over the last 10 years in spite of sophisticated pre and intraoperative imaging techniques. It is postulated that a functional obstruction, due to dysmotility of the SO, lies behind most stone-containing ducts. Thus it seems logical to us that a permanent "fenestration" should be the management of most such ducts. We prospectively followed-up, for one to 10 years, two groups of patients submitted to primary CBDE aiming to assess the short and long-term results of two different surgical approaches to duct lithiasis. In one (Group A) 162 CBDE's were performed, out of 680 CHE's (24%), with a "positivity" of 68% and in the other (Group B) 80 CBDE's, out of 438 CHE's (18%), with a "positivity" of 70%. In Group A a T-tube decompression was used in 79(49%) and a definitive drainage in 83(51%) whereas in Group B the T-tube was employed in only 3(4%) and some form of permanent "fenestration" in 77(96%). There were no significant differences between the operative mortality rates, which were 2.5% in Group A (1 death post T-tube, 3 post CDJ) and 1.3% in Group B (1 death post CDD). The long-term results, though, were significantly worse among patients of Group A whose ducts were temporarily decompressed: 10/79 (12.7%) required further aggressive interventional therapy for retained/recurrent stones while only 3.8% (3/80) in Group A and 1.3% (1/76) in Group B required revisional surgery for bilio-digestive anastomotic complications with cholangitis. It is concluded that it is against the long-term efficiency of the approach utilized in Group B that the new laparoscopic techniques should be compared.

Adult↗

Decompressive craniotomy for acute shaken/impact baby syndrome.

To estimate the surgical efficacy of decompressive craniotomy, 23 children under 2 years of age with acute shaken/impact baby syndrome were treated with medical or surgical methods over the past 6 years. Six children (group A) with lower intracranial pressure (ICP, less than 30 mm Hg) were treated with medical therapy, and 17 children with high ICP (more than 30 mm Hg) of which 7 children were treated with medical therapy (group B) and another 10 children (group C) were treated with decompressive craniotomy. Bifrontal craniotomy was performed on 5 children with generalized brain swelling. A large frontotemporoparietal craniotomy was performed on another 5 children with unilateral swelling. A mean of 32 ml of subdural hematoma was removed. The mean ICP was reduced by 80% in the craniotomy group, p < 0.05. Children in groups A and C performed better on the Children's Outcome Scale than those in group B, p < 0.05. Mortality was significantly lower (0/10) in group C than in group B (3/7), p < 0.05. Hearing preservation was better in group C than in group B, p < 0.05. Bifrontal and frontotemporoparietal craniotomies may reduce mortality and morbidity for acute shaken/impact baby syndrome with high ICP. Patients with ICP less than 30 mm Hg may be treated successfully with medical therapy and patients with ICP more than 30 mm Hg are better treated with decompressive craniotomy.

Battered Child Syndrome↗

Abdominal decompression. An approach towards treating placental insufficiency.

The effects of abdominal decompression applied over a period of several weeks (mean 4 weeks) in late pregnancy on biochemical and haemodynamic parameters as well as fetal growth and cardiotocogram patterns were studied in a group of 64 pregnant women with identified placental insufficiency. A statistically significant improvement was demonstrated in the following findings after treatment: placental perfusion measurements 113mIn and unconjugated oestriol and human placental lactogen, both in serum. A positive influence on antepartum cardiotocogram was observed only immediately after therapy. An acceleration of fetal growth (biparietal diameter) could not be demonstrated. Frequency and severity of EPH gestosis did not change after abdominal decompression. Abdominal decompression seems to be a valuable aid in the still unsatisfactory treatment of placental insufficiency.

Abdomen↗

Pulmonary and left ventricular decompression by artificial pulmonary valve incompetence during percutaneous cardiopulmonary bypass support in cardiac arrest.

BACKGROUND: In cardiac arrest, use of percutaneous cardiopulmonary bypass support (PCPS) may lead to left ventricular loading, with deleterious effects on the myocardium, and is often accompanied by an increase in pulmonary artery pressure. The present study was designed to assess the potential of artificially induced pulmonary valve incompetency to retrogradely decompress the left ventricle during PCPS in ventricular fibrillation. METHODS AND RESULTS: Studies were performed using a standardized experimental animal model in sheep (n = 12; body weight, 77 to 112 kg). When PCPS was used during fibrillation, an increase in left ventricular pressure (from 21.4 +/- 5.0 mm Hg after 1 minute to 28.4 +/- 9.5 mm Hg after 10 minutes of fibrillation) was observed in all animals, with a simultaneous increase in pulmonary artery pressure in 6 animals, from 15.5 +/- 3.8 to 24.3 +/- 5.4 mm Hg (group A). In these animals, artificial pulmonary valve incompetency, which was induced by a special "pulmonary valve spreading catheter," led to effective decompression of both the pulmonary circulation (decrease in pulmonary artery pressure from 24.3 to 11.3 mm Hg) and the left ventricle (decrease in left ventricular pressure from 30.5 to 17.7 mm Hg). We simultaneously measured a decrease in the myocardial release of lactate (increase in arterial coronaryvenous difference in lactate content from -0.01 to 0.14 mmol/L), demonstrating the myocardial protective effect of the procedure. In contrast, in 6 animals without an increase in pulmonary artery pressure during PCPS (group B), artificial pulmonary valve incompetency did not reduce left ventricular loading, which was probably because of competent mitral valves in these animals. CONCLUSIONS: In case of increasing pulmonary artery pressure during PCPS in cardiac arrest, artificial pulmonary valve incompetency might be a useful tool for effective pulmonary and retrograde left ventricular decompression.

Animals↗

Improving active compression-decompression cardiopulmonary resuscitation with an inspiratory impedance valve.

BACKGROUND: Active compression-decompression (ACD) cardiopulmonary resuscitation (CPR) has recently been demonstrated to provide significantly more blood flow to vital organs during cardiac arrest. To further enhance the effectiveness of this technique, we tested the hypothesis that intermittent impedance to inspiratory gas exchange during the decompression phase of ACD CPR enhances vital organ blood flow. METHODS AND RESULTS: ACD CPR was performed with a pneumatically driven automated compression-decompression device in a porcine model of ventricular fibrillation (VF). Nine pigs were randomized to receive ACD CPR alone, while 8 pigs received ACD CPR plus intermittent impedance to inspiratory gas exchange with a threshold valve set to 40 cm H2O. Results comparing 2 minutes of ACD CPR alone versus ACD CPR with the inspiratory impedance threshold valve (ITV) revealed significantly higher mean (+/- SEM) coronary perfusion pressures (diastolic aortic minus diastolic right atrial pressures) in the ITV (31.0 +/- 2.3 mm Hg) group versus with ACD CPR alone (21 +/- 3.6 mm Hg) (P < .05). Total left ventricular and cerebral blood flows, determined by radiolabeled microspheres, were 0.77 +/- 0.095 and 0.47 +/- 0.06 mL/min per gram, respectively, with ACD CPR plus the ITV versus 0.45 +/- 0.1 and 0.32 +/- 0.016 mL/min per gram, respectively, with ACD CPR alone (P < .05). Similar improvements in the ITV group were observed after 7 minutes of ACD CPR. After 16 minutes of VF and 13 minutes of ACD CPR, 6 of 8 pigs in the ITV group were successfully resuscitated with less than three successive 150-J shocks, whereas only 2 of 9 pigs with ACD CPR alone were resuscitated with equivalent energy levels (P < .02). With up to three additional and successive 200-J shocks, all pigs in the ITV group and 7 of 9 pigs with ACD CPR alone were resuscitated (P = .18). CONCLUSIONS: Intermittent impedance to inspiratory flow of respiratory gases during ACD CPR significantly improves coronary perfusion pressures and vital organ blood flow and lowers defibrillation energy requirements in a porcine model of VF.

Animals↗

Phased chest and abdominal compression-decompression. A new option for cardiopulmonary resuscitation.

BACKGROUND: We describe a new manual method of phased chest and abdominal compression-decompression with a Lifestick resuscitator for cardiopulmonary resuscitation (CPR). METHODS AND RESULTS: Ventricular fibrillation (VF) was induced in 20 domestic pigs. After either 5 or 7 minutes of untreated VF, either phased chest and abdominal compression-decompression (Lifestick resuscitator) or precordial compression was initiated. Defibrillation was attempted at 2 minutes after the start of CPR. For the animals in which VF was untreated for 7 minutes, epinephrine was administered in doses of 20 micrograms/kg at 2 minutes after start of CPR. The coronary perfusion pressure generated by the Lifestick resuscitator was more than twofold greater (P < .01) than that generated by conventional precordial compression. Of 5 control animals, none were resuscitated after 5 minutes of VF. However, each of 5 animals treated with the Lifestick resuscitator was resuscitated (P < .01) and survived after 48 hours (P < .01). When untreated VF was prolonged to 7 minutes and epinephrine was administered, only 2 of the 5 control animals were resuscitated, and none of them survived for more than 4 hours. However, each of the Lifestick-treated animals was resuscitated and survived for more than 48 hours (P < .01). CONCLUSIONS: Phased chest and abdominal compression-decompression substantially increased hemodynamic efficacy of CPR and outcome in terms of successful resuscitation, 48-hour survival, and cerebral recovery.

Abdomen↗

Results of microvascular decompression of the eighth nerve as treatment for disabling positional vertigo.

A total of 41 patients who underwent microvascular decompression to relieve disabling positional vertigo in one 12-month period were studied. At follow-up examinations 2 1/2 to 3 1/2 years after the operation, 30 patients had total relief of their symptoms or were considerably improved, to the point that they could resume normal work or other activities in which they were not able to engage before the operation. Two of the 41 patients had mild improvement, and the final 9 patients had no change in their symptoms. One patient, who had had a previous vestibular nerve section without improvement, underwent microvascular decompression of the stump as well as decompression of the opposite side with no relief: 3 of these 9 patients had clear signs of bilateral vestibular nerve compression, but elected not to undergo a second procedure at that time. One patient lost hearing as a result of the operation, and 1 who had a second operation suffered a hearing loss and subsequently underwent vestibular nerve section with improvement of the symptoms. Two patients had transient deficits related to cranial nerves IV and X. The remaining patients had no complications from the operation.

Acoustic Impedance Tests↗

Lateral decompression for malunited os calcis fractures.

Nineteen heels in 19 patients underwent a lateral decompression for hindfoot pain secondary to a malunited os calcis fracture with subtalar intra-articular involvement. The operative procedure consisted of a lateral calcaneal bony prominence removal (ostectomy) and sural nerve release or transection. In addition, the peroneal tendons were released, relocated, and lengthened as necessary, with repair or reconstruction of their retinaculum. Eight patients (group I) had previously undergone a late subtalar fusion without relief of lateral symptoms. Eleven patients (group II) underwent a lateral decompression as an alternative to late subtalar fusion. In both groups combined, there were 14 males and 5 females with an average age of 40 years. The average follow-up was 28 months in group I and 17 months in group II. A satisfactory result was obtained in 75% (6 of 8) of the patients in group I and in 82% (9 of 11) of the patients in group II. This compares to a published success rate of approximately 50% in selected series in the literature and the authors' similar success rate of 46% for late subtalar fusion for the same pathology. The results suggest that the lateral decompression procedure offers a technically simpler yet effective alternative to late subtalar fusion for lateral pain following a malunited os calcis fracture with subtalar intra-articular involvement.

Adult↗

Experimental decompression of the fascial compartments of the foot--the basis for fasciotomy in acute compartment syndromes.

Surgical decompression of the foot by fasciotomy is the only effective means of preventing the late consequences of a compartment syndrome i.e., myoneural ischemia. In this study, a slit catheter system was used to monitor the compartment pressures in experimentally induced compartment syndromes of the foot. The ease and rate of decompressing the intracompartmental pressures via a double incision dorsal approach versus a medial longitudinal approach were compared in 40 paired fresh cadaver specimens. In both methods, intracompartmental pressure is satisfactorily decompressed. However, it takes longer after effective fasciotomies for pressures to normalize via the dorsal approach (11 min versus 1 min; P less than 0.01). The double incision dorsal approach is easier to perform and may be the method of choice for fasciotomy associated with fractures of the forefoot requiring internal fixation.

Acute Disease↗

Hemicraniectomy after middle cerebral artery infarction with life-threatening Edema trial (HAMLET). Protocol for a randomised controlled trial of decompressive surgery in space-occupying hemispheric infarction.

BACKGROUND: Patients with a hemispheric infarct and massive space-occupying brain oedema have a poor prognosis. Despite maximal conservative treatment, the case fatality rate may be as high as 80%, and most survivors are left severely disabled. Non-randomised studies suggest that decompressive surgery reduces mortality substantially and improves functional outcome of survivors. This study is designed to compare the efficacy of decompressive surgery to improve functional outcome with that of conservative treatment in patients with space-occupying supratentorial infarction METHODS: The study design is that of a multi-centre, randomised clinical trial, which will include 112 patients aged between 18 and 60 years with a large hemispheric infarct with space-occupying oedema that leads to a decrease in consciousness. Patients will be randomised to receive either decompressive surgery in combination with medical treatment or best medical treatment alone. Randomisation will be stratified for the intended mode of conservative treatment (intensive care or stroke unit care). The primary outcome measure will be functional outcome, as determined by the score on the modified Rankin Scale, at one year.

Journal Article↗

The incidence and risk factors for hypotension during emergent decompressive craniotomy in children with traumatic brain injury.

We conducted a retrospective cohort study in children <13 yr with traumatic brain injury (TBI) at a Level 1 pediatric trauma center to describe risk factors for intraoperative hypotension (IH) during emergent decompressive craniotomy. Between 1994 and 2004, 108 children underwent emergent decompressive craniotomy for TBI. Overall, 56 (52%) patients had IH. Independent risk factors for IH were each 10 mL estimated blood loss/kg (ARR 1.15 95% CI 1.08-1.22), each mm of computed tomography (CT) midline shift (ARR 1.04 95%CI 1.01-1.07), each 10 mL of CT lesion volume (ARR 1.03 95%CI 1.01-1.05), and emergency department (ED) hypotension (5/5 patients with ED hypotension had IH). CT midline shift > or =4 mm predicted IH (ARR 1.67 95% CI 1.06-2.63), independent of blood loss. IH occurred frequently during emergent decompressive craniotomy in children with TBI. ED hypotension, blood loss, CT lesion volume, and CT midline shift predicted IH. Anesthesiologists can expect children with preoperative CT midline shift > or =4 mm to have IH during this procedure.

Age Factors↗