Venous Sinus Thrombosis-Associated with Posterior Cranial Fossa Surgery. A Systematic Review and Meta-Analysis of Natural History, Risk Factors, Treatment, and Outcome

BACKGROUND

Venous sinus thromboses (VSTs) are rare complications of neurosurgical procedures in the proximity of the dural sinuses. Surgery of the posterior cranial fossa (PCF) and particularly of the cerebellopontine angle (CPA) shows increased risk of VST. VST management is challenging because anticoagulant therapy must be balanced with the risk of postoperative bleeding. We performed a systematic review and meta-analysis to summarize the most important neuroradiologic and clinical aspects of VST after PCF/CPA surgery.

METHODS

We performed a comprehensive literature search to identify articles reporting data on VST after PCF/CPA surgery. We selected only comparative studies providing adequate neuroimaging assessing VST and a control group.

RESULTS

We included 13 articles reporting 1855 patients. VST occurred in 251/1855 cases (estimated incidence, 17.3%; 95% confidence interval [CI], 12.4%-22.2%). Only presigmoid approach (odds ratio [OR], 2.505; 95% CI, 1.161-5.404; P = 0.019) and intraoperative sinus injury (OR, 8.95; 95% CI, 3.43-23.34; P < 0.001) showed a significant association with VST. VST-related symptoms were reported in 12/251 patients with VST (pooled incidence, 3.1%; 95% CI, 1%-5.2%). In particular, we found a significantly increased OR of cerebrospinal fluid leak (OR, 3.197; 95% CI, 1.899-5.382; P < 0.001) and cerebrospinal fluid dynamic alterations in general (OR, 3.625; 95% CI, 2.370-5.543; P < 0.001). Indications for VST treatment were heterogeneous: 58/251 patients underwent antithrombotics, with 6 treatment-related bleedings. Recanalization overall occurred in 56.4% (95% CI, 40.6%-72.2%), with no significant difference between treated and untreated patients. However, untreated patients had a favorable outcome.

CONCLUSIONS

VST is a relatively frequent complication after PCF/CPA surgery and a presigmoid approach and intraoperative sinus injury represent the most significant risk factors. However, the clinical course is generally benign, with no advantage of antithrombotic therapy.

An Effective Surgical Technique for Limb Salvage in Femorodistal Bypass

Usually, the extension of revascularization of lower extremities to the distal arteries is performed to avoid limb amputation.

Technical errors in the performance of the distal anastomosis or poor runoff cause early failure of the bypass; myointimal fibroplasia or new atherosclerosis at the distal suture edges cause long-term failure.

A new modified technique was used in 20 patients to facilitate the perform ance of the distal anastomosis. A vein patch is employed to widen the distal arteriotomy, and then, the graft is sutured into the vein patch so that the caliber of the distal artery is increased; potential technical defects and the risk of an early thrombosis are thus avoided.

Care is always taken to guarantee a backflow in the vessel, which will permit limb salvage even if the distal runoff is not maintained in long-term follow-up because of occlusion of the outflow.

From 1979 to 1985, 20 patients underwent 21 distal arterial reconstructive procedures with this new technique. All patients presented an absolute indica tion for surgery: rest pain (6), gangrene or ulcer (12), and severe ischemia (2). For the bypass procedure, the great saphenous vein was employed in 13 cases and PTFE in 8. Three major amputations were necessary within eight days of the operation. There was no operative mortality. Long-term patency rate was very high (85%).

Detection of calbindin-D immunoreactivity in human follicular dendritic cells

The calcium-binding protein calbindin-D (28 kD) has been analysed immunohistochemically in different human lymphoid tissues. Combined immunohistochemical staining showed that calbindin-D (28 kD) is expressed by only a proportion of dendritic cells within the light zone of germinal centres, where antigens in the form of immune complexes are trapped and presented to B lymphocytes. All other cell types including macrophages, interdigitating cells, and various lymphocyte populations were negative. The expression of calbindin-D in this functionally relevant subset of follicular dendritic cells could have a role in the regulation of proliferation and selection of memory B-cells by modulating the concentration of calcium ions. Calbindin-D may be a useful marker for analysing in situ the phases of follicular development in different physiological and pathological conditions.

Laser resonators containing self-focusing elements

Laser resonators containing self-focusing elements are described using the matrix formalism appropriate for Gaussian beams. The laser rods are not approximated by traditional optical elements but treated as thick materials showing a radial quadratic dependence of their refractive index. Cavities incorporating an arbitrary number of lenses, mirrors, and crystals (including rods with spherical endfaces) are described with no restriction on the value of the pump power. Stability domains and beam size in the resonator and inside the rods are calculated. A few experimental tests with Nd:YAP lasers are presented.

The effect of several viper venoms on prothrombin Padua

The effect of four viper venoms (Oxyuranus scutellatus, Notechis scutatus scutatus, Echis carinatus, Naja nigricollis) on prothrombin Padua has been studied. Using Oxyuranus scutellatus venom and Notechis scutatus scutatus venom, prothrombin activity resulted to be moderately decreased similarly to what observed with other one-stage and two-stage methods. On the contrary, using Echis carinatus venom a normal level was obtained. No clotting was observed using the Naja nigricollis venom, regardless of the concentration used. The normal level of factor II obtained with Echis carinatus venom as compared with the low levels obtained with the other venoms, suggests that it acts on a different site of the prothrombin molecule.